Method and apparatus for hybrid vehicle auxiliary battery state of charge control

The present invention relates to a method and an apparatus for hybrid vehicle auxiliary battery state of charge control. In one embodiment, the present invention is an automobile including an electronic accessory, a first battery connected to the electronic accessory, and a control unit connected to the first battery, the control unit monitoring the first battery and disconnecting the first battery from the electronic accessory when the first battery is in a first operational condition.

BACKGROUND

The present invention relates to a method and an apparatus for hybrid vehicle auxiliary battery state of charge control.

In an automobile, a user can often activate and use accessories in the automobile such as a radio or a light, even when the engine is not activated. This can drain a battery of the automobile such that the user is unable to start the engine of the automobile.

Thus, there is a need for a method and apparatus to reduce the likelihood of the battery being drained such that the user is unable to start the engine of the automobile.

SUMMARY

In one embodiment, the present invention is an automobile including an electronic accessory, a first battery connected to the electronic accessory, and a control unit connected to the first battery, the control unit monitoring the first battery and disconnecting the first battery from the electronic accessory when the first battery is in a first operational condition.

In another embodiment, the present invention is an automobile including an electronic accessory, a first battery connected to the electronic accessory, an engine configured to be in an active or inactive state, a control unit connected to the first battery and the engine, the control unit monitoring the first battery, disconnecting the first battery from the electronic accessory when the first battery is in a first operational condition, and providing a warning to a user when the first battery is in a second operational condition.

In yet another embodiment, the present invention is a method for controlling state of charge in an auxiliary battery in an automobile including the steps of monitoring an operation condition of the auxiliary battery, and disconnecting the auxiliary battery from electronic accessories when the auxiliary battery is in a first operation condition.

DETAILED DESCRIPTION

Apparatus, systems and methods that implement the embodiments of the various features of the present invention will now be described with reference to the drawings. The drawings and the associated descriptions are provided to illustrate some embodiments of the present invention and not to limit the scope of the present invention. Throughout the drawings, reference numbers are re-used to indicate correspondence between referenced elements.

FIG. 1is a schematic diagram of an embodiment of the present invention. As seen inFIG. 1, an automobile2can include an engine4, a starter6, a main battery8, a control unit10, an auxiliary battery12, accessories14, a key reception unit16, and a warning unit20.

As depicted inFIG. 1, automobile2is a hybrid car. Although automobile2is a hybrid car, automobile2can be, for example, any suitable car for transportation such as a car with a conventional internal combustion engine, and/or a car with a hydrogen engine.

Engine4can be an internal combustion engine suitable for use in a hybrid car. Engine4can also be an electric engine or an engine to process hydrogen, ethanol, or other types of fuel. Engine4is connected to starter6, auxiliary battery12, and main battery8through a switch22. Engine4can be in an active state or inactive state. In an inactive state, engine4is off and is not running while in an active state, engine4is on and is running.

Starter6is connected to engine4. It is also connected to main battery8through switch22which can be either engaged or disengaged. Starter6can start engine4through electricity supplied by main battery8when switch22is engaged. Starter6can include, for example, spark plugs.

Main battery8is connected to control unit10, engine4and starter6through switch22, and auxiliary battery12through switch24. Main battery8can be, for example, a high voltage battery. Main battery8can supply electricity to engine4and/or starter6when switch22is engaged. Furthermore, when engine4is active and switch22is engaged, main battery8can provide power to aid engine4in moving automobile2. Also when switch22is disengaged, electricity from main battery8does not flow to engine4and/or starter6. Advantageously this can improve the safety of automobile2by preventing accidental discharges to engine4and/or starter6since main battery8can be a high voltage battery. With regards to switch24, when switch24is engaged, main battery8can supply electricity to auxiliary battery12. When switch24is disengaged, electricity does not flow from main battery8to auxiliary battery12.

Auxiliary battery12is connected to engine4, accessories14, control unit10, and switch22. Auxiliary battery12is also optionally connected to main battery8. Auxiliary battery12can be a battery with a smaller energy storage capacity than main battery8. Advantageously this could reduce the weight of automobile2which can be particularly useful when automobile2is a hybrid car. In one embodiment, auxiliary battery12is a 12 volt battery. Auxiliary battery12may be connected to main battery24through switch24and accessories14through switch26. Switch24and switch26can be configured to be engaged or disengaged. As noted, when switch24is engaged, electricity can flow from main battery8to auxiliary battery12. When switch24is disengaged, electricity may not flow from main battery8to auxiliary battery12. Advantageously this can improve the safety of automobile2since main battery8can be a high voltage battery.

When switch26is engaged, auxiliary battery12can supply electricity to accessories14. When switch26is disengaged, electricity can be prevented from flowing to accessories14. Advantageously, this can reduce the amount of electricity used by accessories14and prevent auxiliary battery12from being depleted or drained, such as when engine4is inactive or off. When engine4is active, engine4can recharge and replenish auxiliary battery12. Furthermore, auxiliary battery12can also control switch22by supplying electricity to engage or disengage switch22. As previously noted, the engagement of switch22allows main battery8to supply power to start engine4using starter6.

Key reception unit16is connected to control unit10and can accept a key18which can engage key reception unit16. Key18can engage key reception unit16either physically, such as when key18is physically placed inside key reception unit16, or wirelessly, such as when key18transmits a signal to key reception unit16and/or key18establishes communication with key reception unit16. Key18can engage key reception unit16in two or more states such as an ACCESSORIES ON state or an ENGINE ON state.

In the ACCESSORIES ON state, accessories14can be activated. It is also contemplated that some accessories14can be activated without key18being engaged with key reception unit16, or without key18being engaged with key reception unit16in the ACCESSORIES ON state. In such a case, the remaining accessories can be engaged when key18is engaged with key reception unit16in the ACCESSORIES ON state. During the ACCESSORIES ON state, engine4is inactive. The ACCESSORIES ON state can also be referred to as the READY OFF state.

In the ENGINE ON state, engine4is activated. Furthermore, during the ENGINE ON state, auxiliary battery12can supply electricity to accessories14and engine4can recharge auxiliary battery12. The ENGINE ON state can also be known as the READY ON state.

Warning unit20is connected to control unit16and/or auxiliary battery12. Warning unit12can be, for example, an audio emission device, a video display, and/or a combination of the audio emission device and the video display. Thus, warning unit12can provide a warning to a user such as an audio warning, visual warning, or and audiovisual warning to the user.

Control unit10is connected to main battery8, auxiliary battery12, switch24, switch26, key reception unit16, and warning unit20. Control unit10can be an engine control unit, a microprocessor, an on-board diagnostics system, a computer chip, and/or any other device that can control or monitor the functions and/or components of automobile2. Control unit10can thus monitor auxiliary battery12and determine the voltage, power, and/or current level of auxiliary battery12. Furthermore, control unit10can also instruct auxiliary battery12to supply power to engage or disengage switch22. Control unit10is also connected to key reception unit16and receives a signal from key reception unit16regarding the engagement of key18to key reception unit16. Based on the signal, control unit16can also control switch24and switch26to engage or disengage appropriately. Control unit10can also determine whether key18is engaged with key reception unit16in an ENGINE ON state or ACCESSORIES ON state.

Control unit10also controls warning unit20to display or sound an alarm at appropriate times. By selectively controlling switch26and warning unit20, control unit10can warn a user when accessories14should be turned off and also when auxiliary battery12will be disconnected from accessories14. Control unit10can also warn a user to activate engine4so that auxiliary battery4can be replenished. By disconnecting auxiliary battery12from accessories14, the present invention can advantageously preserve a sufficient state of charge within auxiliary battery12to engage switch22when a user wishes to drive automobile2. Otherwise, if auxiliary battery12is drained, then auxiliary battery12may not have a sufficient state of charge to engage switch22to allow main battery8to start engine4using starter6.

FIG. 2is a flow chart of an embodiment of the present invention in operation. As seen inFIG. 2, the process begins in step S200. In step S212, control unit10determines whether engine4is active or not. Engine4can be active, for example, when key18is engaged with key reception unit16in an ENGINE ON state. Engine4is inactive when key18is disengaged from key reception unit16and/or key18is engaged with key reception unit16in an ACCESSORIES ON state but not in an ENGINE ON state. If engine4is active, then the process ends in step S222.

Otherwise, if engine4is inactive, the process continues in step S214. In step S214, control unit4determines whether auxiliary battery12is operating in a warning condition. For example, auxiliary battery12can be operating in a warning condition when the engine is inactive and when a voltage of auxiliary battery12falls below a first predetermined voltage threshold, a power of auxiliary battery12falls below a first predetermined power threshold, and/or a current of auxiliary battery12falls below a first predetermined current threshold. For example, if the first predetermined threshold for auxiliary battery12is 6 volts and the voltage of auxiliary battery12is 5 volts, then auxiliary battery12is operating in a warning condition. Furthermore, auxiliary battery12could be operating in a warning condition when the engine is inactive when a first predetermined amount of time has expired from a triggering event, such as when accessories14is activated. For example, if the first predetermined amount of time is 30 minutes and more than 30 minutes has elapsed since accessories14was activated, then auxiliary battery12is operating in the warning condition when the engine is inactive. If auxiliary battery12is not operating in the warning condition, then the process repeats step S212.

If, however, auxiliary battery12is operating in the warning condition, then in step S216, control unit10provides a warning to a user using warning unit20. The warning can be an audio or visual warning to indicate to the user that he should turn off or deactivate accessories14. The warning can also be an audio or visual warning to indicate to the user that auxiliary battery12has a low state of charge. The warning can also indicate to the user that the user should activate engine4such as by engaging key18with key reception unit16in an ENGINE ON state. By activating engine4, it is contemplated that engine4could recharge auxiliary battery12.

In step S218, control unit10determines whether auxiliary battery12is operating in a shut off condition. Auxiliary battery12is operating in the shutoff condition when the engine is inactive and when a voltage of auxiliary battery12falls below a second predetermined voltage threshold, a power of auxiliary battery12falls below a second predetermined power threshold, and/or a current of auxiliary battery12falls below a second predetermined current threshold. The second voltage threshold is less than the first voltage threshold, the second power threshold is less than the first power threshold, and the second current threshold is less than the first current threshold.

Thus, if the first voltage threshold was 6 volts, then the second voltage threshold can be, for example, 4 volts. If the voltage of auxiliary battery12was 5 volts, then auxiliary battery12would be operating in the warning condition but not in the shut off condition since 5 volts is greater than the second voltage threshold of 4 volts. However, if the voltage of auxiliary battery12had dropped to 3 volts, then auxiliary battery12would be operating in the shut off condition since 3 volts is less than the second voltage threshold of 4 volts.

Furthermore, auxiliary battery12could be operating in a shutoff condition when the engine is inactive and when a second predetermined amount of time has expired from a triggering event, such as when accessories14is activated. The second predetermined amount of time can be a greater amount of time than the first predetermined amount of time. For example, if the first predetermined amount of time is 30 minutes and more than 40 minutes has elapsed since accessories14was activated, then auxiliary battery12is operating in the shutoff condition when the engine is inactive. If auxiliary battery12is not operating in the shut off condition, then the process repeats step S212.

If, however, auxiliary battery12is operating in the shut off condition, then in step S220, control unit10disengages switch26to disconnect auxiliary battery12from accessories14. This may be especially useful when auxiliary battery12has a relatively low charge capacitance when compared to the electrical demands of accessories14. That is, when accessories14may drain auxiliary battery12in a relatively short period of time such as in an hour or a few hours.

Optionally, control unit10can also display another warning to the user indicating that auxiliary battery12has been disconnected from accessories14. The warning can also include instructions to activate engine4by engaging key18with key reception unit16in an ENGINE ON state. In step222, the process ends.

In one embodiment, switch24can be engaged to replenish auxiliary battery12at either step S216or step S220. This can be done, for example, only when control unit10detects that key18is engaged with key16and that there is sufficient energy within main battery8to replenish auxiliary battery12.

Advantageously this can replenish auxiliary battery12while reducing the likelihood that main battery8is discharged because if key18is engaged with key reception unit16, it is contemplated that the user is present. If the user is present, then the user can activate engine4to recharge auxiliary battery12.

Furthermore, if the user is not present, then it may be less critical that accessories14remain active or have the ability to remain active. Also, if main battery8is a high voltage battery, then it may be beneficial to reduce the amount of time when main battery8is connected to auxiliary battery12such as when the user is not present in automobile2.

In another embodiment, as soon as engine4is activated, the process moves to step S222and ends. This is because as soon as engine4is activated, then engine4is used to recharge auxiliary battery12. This may reduce the necessity for auxiliary battery12to be disconnected from accessories14.

In yet another embodiment, key18can engage key reception unit16in a third state such as an IGNITION OFF state. During the IGNITION OFF state, switch26is disengaged, preventing power from flowing from auxiliary battery12to accessories14. In such an embodiment, during an ACCESSORIES ON state and an ENGINE ON state, switch26is engaged allowing power to flow from auxiliary battery12to accessories14.

The previous description of the disclosed examples is provided to enable any person of ordinary skill in the art to make or use the disclosed methods and apparatus. Various modifications to these examples will be readily apparent to those skilled in the art, and the principles defined herein may be applied to other examples without departing from the spirit or scope of the disclosed method and apparatus. The described embodiments are to be considered in all respects only as illustrative and not restrictive and the scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.