Patent ID: 12196145

DETAILED DESCRIPTION

Referring in more detail to the drawings,FIG.1illustrates a vehicle10that has an engine11coupled to one or more wheels12to drive the wheels12and move the vehicle10. The vehicle10includes one or more brake assemblies14associated with the wheels12to enable a driver or system to reduce the speed of the vehicle and stop the vehicle, and retain the vehicle stopped, when desired. Various vehicle systems and accessories are provided with electrical power by an electrical system16that may include one or more batteries, and an electrical generator18driven by the engine11when the engine11is operating. To control operation of various vehicle systems and accessories, a vehicle control system20may be coupled to the electrical system16and to the vehicle systems and accessories.

The engine11may be an internal combustion engine, or it could be an electric motor or the like. The generator18may have an input that is coupled to a rotating output of the engine11by a power transmission member, like a belt or chain, so that rotation of the input generates electricity that can be used to power various things in the vehicle10. The generator18may be an alternator commonly provided in vehicles. So arranged, the engine11drives the vehicle wheels12to move the vehicle10, and also drives the generator18to produce electricity used in operation of the vehicle systems and accessories.

The vehicle electrical system16may receive electrical power from one or both of the battery and the generator18, and may provide power to various devices. Examples of devices include audio-visual devices in the vehicle, heating and cooling devices (e.g. HVAC system, seat heaters or coolers), electric motors (e.g. to move mirrors, seats, etc.), pumps, electrical outputs to charge batteries of remote devices (e.g. mobile phones), and the like. Further, the vehicle10may have electrical outlets via which accessories may be plugged into the vehicle10and powered by the electrical system16.

The brake assemblies14may be of any suitable type, for example, a disc or drum type brake assembly, and may include a brake actuator, which may be a pedal, that is coupled to a brake member. The brake member (e.g. a brake pad or drum shoe) is associated with a vehicle wheel12and arranged to frictionally engage and slow or inhibit rotation of a vehicle wheel12.

The control system20may include one or more controllers22, and the controllers22may be coupled in any desired way and arrangement to the engine11, generator18, electrical system16and other vehicle10components. In order to perform the functions and desired processing set forth herein, as well as the computations therefore, the controllers22may include, but not be limited to, a processor(s), computer(s), DSP(s), memory, storage, register(s), timing, interrupt(s), communication interface(s), and input/output signal interfaces, and the like, as well as combinations comprising at least one of the foregoing. For example, a controller22may include input signal processing and filtering to enable accurate sampling and conversion or acquisitions of such signals from communications interfaces and sensors.

As used herein the terms control system20or controller22may refer to one or more processing circuits such as an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that executes one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality.

As shown inFIG.2, the electrical system16and control system20may include or be communicated with various sensors, such as a brake sensor24, vehicle speed sensor26, engine speed sensor28and an electrical sensor30, by way of non-limiting examples. The brake sensor24is associated with the brake assembly14and provides an output to the control system20that is indicative of some actuation or state of the brake assembly14. For example, the brake sensor24may be responsive to the position (or change thereof) or motion of part of the brake assembly14, like a caliper or the brake actuator (e.g. pedal). The brake sensor24could be responsive to a brake fluid pressure within the system, or the braking force applied by or to the brake member or brake actuator. Actuation of the brake assembly14slows the vehicle10and can cause other functions to occur, such as illumination of brake lights and disengagement of a throttle control system (e.g. cruise control).

The vehicle speed sensor26can be used to determine a rate of speed and a rate of change of vehicle speed, and whether the vehicle speed is increasing or decreasing. The control system20may be communicated with the vehicle speed sensor26and may provide a display of vehicle speed within the vehicle10, may use the vehicle speed sensor output to control a cruise control system, and for other functions. The speed sensor output may also be used to determine when a vehicle10is stopped or coming to a stop.

The control system20may also include one or more electrical sensors30by which the electrical load or demand of at least part of the electrical system16can be determined, where such determination may be an estimation. The control system20can utilize information/output from the electrical sensor(s)30to limit total electrical demand in the vehicle10in view of electrical power available in the vehicle10, to prevent damage to a system or component, or otherwise as desired. The electrical sensors30could be discrete components, or various electrical components can be communicated with one or more controllers22of the control system20and provide signals or information indicative of their current draw or electrical power use, which signals or information can be used by the control system20to determine the electrical load of all or part of the electrical system16, and the electrical sensor(s) can be considered to be the outputs/inputs that provide such information.

In use of the vehicle10, the electrical demand of things within the electrical system16can vary. For example, the heating and cooling systems and components can be operated at different output levels that have different electrical requirements. Further, other components like coolant fluid pumps and fuel pump motors, may have variable output and variable electrical loads. Display screens, audio equipment, lights and other things may be on or off, or operated at varying outputs, and thus, have variable electrical loads.

The electrical generator18may have an electrical output that varies as a function of the engine rotary speed, with an electrical output at lower engine speeds being less than the electrical output at higher engine speeds. An engine11may be designed to idle at a nominal idle speed which represents an intended lowest rotary speed of the engine11which may occur without throttle input by the driver of the vehicle10. The electrical generator18is driven by the engine11and has its lowest electrical output when the engine11is at idle speed. Suitable rotary speed control may be achieved with pulleys or gears of varying sizes to provide a rotary speed of the electrical generator18that achieves a desired electrical output. For example, a nominal idle speed of an engine11may be about 600 to 1,000 rpm, and the electrical generator18may have a rotary speed that is 1.5 to 4.5 greater when the engine11is operating at the nominal idle speed.

In at least some situations, when the electrical generator18is driven at a low speed, a high electrical power demand in the vehicle electrical system16might exceed the power output by the electrical generator18. In such a situation, there would be insufficient electrical power to fully power all components or systems that are drawing current in the electrical system16.

One way to deal with this problem is to manage the current flow based upon a predetermined priority so that more important or higher priority components for a given state of engine/vehicle operation receive the electric current/electrical power they need and lower priority components receive less than demanded or no current/electrical power. Another way to deal with this problem is to increase the rotary speed of the electrical generator18, by increasing the engine rotary speed, to thereby increase the power output from the electrical generator18. And a combination of these two ways to deal with the problem may be used, as desired. That is, the electrical output of the generator18may be increased by increasing the engine speed, and a reduction or other control of power provided to at least certain components may be employed.

One implementation of a method40of controlling operation of the engine11, and hence, the electrical generator18, is shown inFIG.5. The method may start at step42when it is determined that the engine11is idling, and when that is determined, the method may continue to step44in which it is determined if an actual or projected electrical load in or of the electrical system16is beyond a threshold. If the electrical load is beyond the threshold, the method may continue to step46and determine if the brake14is applied, and if it is, the method may proceed to step48. In step48, the engine speed may be set to a target speed greater than the idle speed of the engine11, this increases the speed at which the electrical generator18is driven and thus, increases the electrical output of the electrical generator18.

In this method, the increased engine speed may be maintained until it is determined, in step50, that the vehicle brake14is being released which indicates that the driver is intending to move the vehicle10. When it is determined that the vehicle brake14is being released, the method proceeds to step52in which the engine speed is reduced from the speed set in step48and to or toward the engine idle speed, and thereafter, the method ends at54.

Reducing the engine speed to or toward the engine idle speed reduces the torque of the engine11that is input to the vehicle10when the vehicle brake14is fully released and forward (or rearward) travel of the vehicle10is initiated, to provide a smoother acceleration response of the vehicle10. If the brake14were fully released when the engine11was still being operated at the higher than idle engine speed, a greater initial torque would be applied to the vehicle10causing the vehicle10to accelerate more rapidly, and/or provide an impulse or jerking motion to the vehicle10that would, undesirably, be experienced by passengers in the vehicle10. Reducing the engine speed does reduce the rotary speed of the electrical generator18and thereby reduces the electrical output of the generator18, but this reduction in generator18output is temporary and upon acceleration of the engine11by the driver to move the vehicle10, the speed of the generator18and its electrical output are soon increased. Thus, an associated reduction in power provided to one or more electrical components is temporary.

Thus, the electrical generator18may have a first power output at a rotary speed of the electrical generator18associated with nominal idle engine operation, and the electrical generator18may have additional power output levels including a second power output that is higher than the first power output and which is associated with an engine rotary speed greater than idle, when the rotary speed of the electrical generator18is higher. In at least some implementations, the generator produces power at a certain voltage or within a smaller range of voltages, for example at 12 to 15 volts, and the power output variance is a difference in the maximum current that can be provided by the generator18.

The method may include more or fewer steps, and the steps of the method may be implemented in different ways. For example, the determination in step42that the engine11is idling may be accomplished by determining that the vehicle speed is zero, which information may be provided by the vehicle speed sensor26. Additionally, an engine speed sensor28, sometimes called a tachometer may provide information to the control system20that the engine rotary speed is below a threshold associated with the engine11idling, where the engine idle speed may vary within a known or assumed range in operation of the engine11. The threshold may be higher than the nominal idle speed, with a non-limiting example threshold being 100 rpm higher than the nominal idle speed. Moreover, any combination of vehicle speed sensor(s), engine speed sensor(s) and acceleration pedal position sensor(s) may provide information to the control system that the engine is idling.

In at least some implementations, the vehicle speed may be monitored and when the vehicle speed is decreasing and is below a threshold, the method40may either increase the engine rotary speed to the target speed, or if the engine speed is at or greater than the target speed, the method may prevent the engine speed from decreasing below the target speed as the vehicle speed decreases to zero. In this way, the engine speed can be at the target speed when the vehicle10comes to a stop, and the method need not wait for the vehicle speed to be zero before setting the engine speed to the great than idle target speed. The method/system may also check to determine that the brake14is being applied as the vehicle speed is decreasing, if desired.

Next, the determination of the electrical load can be done in different ways. For example, the combined current draw of each component of the system can be determined by one or more controllers22and summed up to provide an actual electrical load, or the electrical load may be estimated. The load may be estimated, for example, by using predetermined or assumed values for different components, where those values may be stored in a look-up table or map as a fixed value or a changing value (e.g. low, medium and high values for different levels of operation and demand). In such a method or system, when use of a component is determined, a predetermined electrical load value is used in a summation of electrical loads, without having to determine the actual, instantaneous load of that component. This may be done for any number of components, up to all of them, or for a few components, such as those that have a high current draw, at least at maximum operation, like the air conditioner, seat heaters or coolers, or auxiliary components that may be plugged into an electrical outlet in the vehicle10.

In one example, the necessary electrical components in the electrical system16, which are those needed for operation of the vehicle10, such as controllers22, fuel pump, coolant pumps and the like, may collectively be assigned one or more predetermined electrical loads (a single value or values depending upon levels or thresholds of operation/demand). In other words, the load of multiple components may be combined into a single value in a given analysis of electrical load, and the load of other components may be added to this value to give an estimated total electrical load in step44.

The target engine speed may be a single value or a range of values which may, for example, be dependent upon the determined electrical load to be met by the electrical generator18. By way of non-limiting examples, the target engine speed may be a set value, perhaps 1,000 rpm or within a range of 900 rpm to 1,200 rpm, or perhaps 300 rpm greater than the nominal idle speed or within a range of 200 rpm to 400 rpm greater than the nominal idle speed. The target engine speed could be a variable target engine speed that is determined as a function of the determined electrical load, where a higher determined electrical load results in a higher target engine speed, and vice versa, to provide an electrical output from the generator18that matches more closely the instantaneous electrical power needed in the electrical system16. The engine speed may be increased or maintained at the target engine speed by any suitable means, including but not limited to increasing throttle, or changing fuel supply or ignition timing in the engine11, or some combination of two or more of these.

The target engine speed could be determined as a function of the brake force applied, where a determination that the braking force is not sufficient to hold the vehicle10stopped at a higher target engine speed would result in setting the target engine speed lower to ensure the vehicle10remains stopped at the target engine speed used. This could be based upon a maximum braking force for a vehicle10and other factors related to braking force, like the inclination of the vehicle10, where a vehicle10facing uphill may permit higher target engine speed than a vehicle10facing downhill because of the increased braking force needed to hold a downhill facing vehicle10stopped. A determined target engine speed could be reduced if vehicle movement is detected, such as may be determined from the output of the vehicle speed sensor26.

The step of determining that the brake14is being released may be accomplished with feedback from the brake sensor24. To enable a smoother acceleration of the vehicle10without a high torque impulse caused by the engine11operating at the target engine speed, it is desirable to reduce the engine speed before the brake14is fully released. Accordingly, the brake sensor24can provide feedback to the controller22for determination of when the brake14is being released. This determination may be made based upon a detected change in the brake assembly14. For example, the magnitude (i.e. amount) or rate of movement of the brake pedal/actuator may be determined by a brake position sensor that may be associated with the brake pedal/actuator, or by a reduction in fluid pressure in the brake assembly14(e.g. hydraulic brake fluid) if such information is available in or to the control system20. Typical brake pedal release rates can vary anywhere from 10%/s to 1000%/s. Typical brake pedal position movements can vary anywhere from 10 mm to greater than 200 mm in different applications.

When it is determined that the brake14is being released, and preferably before the brake14is fully released, the engine speed may be decreased to or toward the nominal idle speed by any suitable means, including but not limited to decreasing throttle, or changing fuel supply or ignition timing in the engine11, or some combination of two or more of these. Then, when the brake14is fully released, the torque input from the engine11is reduced compared to what it would have been at the target engine speed, and this permits a lower torque impulse and a smoother acceleration of the vehicle10.

FIG.3illustrates an example of the method described herein. InFIG.3, at time zero (0), the vehicle brake assembly14is applied, as shown by line60, the engine11is initially at a nominal idle speed, as shown by line62, the electrical load is at a first level, as shown by line64, the electrical load is less than the generator18output at engine idle speed, as shown by line66, and the vehicle speed is zero (0) as shown by line68which is coincident with the horizontal axis of the graph when the vehicle speed is zero. At time (1), the electrical load increases to a higher, second level, as shown by the change in line64, and the second level in this example is greater than an electrical load threshold, and may be greater than the electrical output66of the generator18when the engine11is at the nominal idle speed. As a result of the increased electrical load64, at time (2) the engine speed62is increased to the target engine speed, and this increases the electrical output66of the generator18to a second level which, in this example, is greater than the second level of electrical load64.

Next, at time (3), the brake60is starting to be released and after a threshold release/movement of the brake14, the engine speed62is decreased beginning at time (4) and ending at time (5), and at or soon after time (5), the engine speed62is increased by a user moving a throttle input (e.g. accelerator pedal), and the vehicle speed68increases accordingly, as does the electrical output66of the generator18.

FIG.4is a graph similar toFIG.3. In this example, the vehicle speed68is decreasing to zero between time (0) and time (1), as the brake60is applied. As the engine speed62is decreasing toward the nominal idle speed, the electrical load64is determined to be higher than the electrical load threshold (which may be an electrical load that is or is a function of the output of the generator18when the engine is at its nominal idle speed), so the engine speed62is prevented from decreasing below the target engine speed, which keeps the electrical output66of the generator18at the second level, which in this example is higher than the electrical load64. The process from time (3) to time (5) and beyond may be the same as described with reference toFIG.3.

Accordingly, an increase in the electrical output of an engine-driven electrical generator can be achieved in certain instances where the electrical demand is higher than a threshold, and may be higher than an output of the electrical generator associated with a given engine speed. Further, when a vehicle brake is being released and the engine speed is higher than a nominal idle speed, a reduction in the engine speed may be achieved prior to full release of the brake or brake assembly to reduce the magnitude of a torque from the engine when the brake is fully released. This reduces or eliminates a jerking or lurching of the vehicle and provides a better passenger experience in use of the vehicle.