Patent Application
20100017070
Some vehicles, in particular vehicles equipped with an automatic transmission, may be equipped with a hill holding control feature to prevent or reduce rollback until the engine is fully engaged with the transmission to move the vehicle forward. The hill holding control may include a brake control configured to apply brakes to the wheels of the vehicle until the engine provides enough torque to begin moving the vehicle forward. However, if the brakes are applied for too long, or with too much force, the engine competes with the brake force and fuel may be wasted. In order to reduce fuel loss, the brake force applied, or the length of time the brakes are applied may be adjusted according to a degree of incline of the hill.
Vehicles may also be equipped with a downhill control feature in order to avoid excess speed when traveling down an incline. The downhill control feature may implement actions such as applying the brakes, and reducing engine torque to use engine inertia to slow the vehicle. Downhill control typically applies right and left brakes equally to slow the vehicle. The amount of downhill control may also be adjusted according to the degree of incline.
Some vehicles may be equipped with Electronic Stability Control (ESC) to increase vehicle stability. In recent years control features have been added to vehicles to decrease the likelihood of a vehicle rollover. These features may be referred to as Roll Stability Control or RSC®, a registered trademark of the Ford Motor Corporation. RSC may monitor the vehicle's stability using a number of sensors configured to sense the physical disposition of the vehicle such as the roll angle and roll rate of the vehicle, and then take corrective action that may include reducing engine torque and/or braking one or more wheels.
However, rollover conditions may be rare. On the other hand, driving on, or stopping on, an incline may be more common. Thus the inventors herein have recognized various approaches that enable system integration. For example, a method, apparatus, and a system that provides an efficient arrangement of a vehicle inclination sensor that may be used, where the sensor provides inclination data for RSC, hill-holding and/or downhill control. The method, apparatus, and a system may also provide logic that may increase the performance features of the RSC so that they take precedence over the hill-holding and/or downhill control.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.
A vehicle system, for an engine propelled vehicle, is described having an inclined surface control, and an electronic vehicle stability control (ESC), such as roll stability control (RSC), that may both receive input from a common vehicle inclination sensor.
The inclined surface control may include a hill holding feature and a downhill control feature. The hill holding feature may be implemented in the case of the vehicle starting up an incline from a stop, or near stop, and may selectively activate a braking mechanism until the engine torque is above a predetermined threshold to move the vehicle forward and up the incline without any significant rollback. The braking mechanism may be configured to brake one or more wheels on the respective right side and left side of the vehicle substantially equally.
The downhill control feature may be implemented in the case of the vehicle moving downhill, and may be used to control vehicle speed. The downhill control feature may also activate the braking mechanism, and may, in addition, control the engine to limit torque to control the downhill speed of the vehicle. The braking mechanism may also be configured to brake one or more wheels on the respective right side and left side of the vehicle substantially equally.
In both cases, the hill holding and downhill control, the desired amount of braking and engine control may be a function of a degree of inclination of the vehicle. Accordingly, the vehicle may include a vehicle inclination sensor, such as a longitudinal accelerometer, configured to provide output to the braking mechanism, and to an engine controller to control engine torque.
The RSC may include a number of sensors configured to monitor the disposition of the vehicle. The sensors may be used to provide input to automate control of one or more vehicle brakes to reduce a roll tendency of the vehicle during turning, or other, conditions. In various embodiments, the vehicle inclination sensor used for the inclined surface vehicle control may also be used for the RSC. Alternatively the vehicle inclination sensor used for the RSC may also be used for the inclined surface vehicle control.
In various embodiments, the sensor information from the vehicle inclination sensor may be processed through a filter and/or modified based on other sensor information to more accurately reflect the relevant data for the particular control feature. For example, accelerometer data from a longitudinal sensor at low frequencies can be used to identify road grade, whereas data from the sensor in a broader range of frequencies may be used to control vehicle stability, such as for roll stability control.
The inventors have recognized that, depending on the disposition of the vehicle, the signal from the vehicle inclination sensor may have decipherable characteristics indicative of the type of motion the vehicle is experiencing. For example, a signal detected from the vehicle inclination sensor during conditions wherein a rollover may be possible may change more rapidly, whereas a signal detected from the vehicle inclination sensor when traveling downhill, or stopped on an uphill grade, or when moving from one incline to another, may change more slowly. Specifically, the relatively more dynamic nature of a rollover condition when compared to a downhill traverse. Similarly, the signal detected from vehicle inclination sensor when the vehicle is stopped on an incline may also change more slowly than rollover conditions. Accordingly, by appropriately filtering and/or modifying the signal differently for the various different control operations, the same sensor signal may be used to affect both RSC and inclined surface control.
In addition, the vehicle inclination sensor may pick up signal components from road surface irregularities and/or engine vibrations. These signal components may be filtered out from the vehicle inclination sensor signal for use with both the inclined surface control, and the RSC.
Further, various embodiments may use signals from sensors other than the vehicle inclination sensor to more accurately reflect the type of motion the vehicle is experiencing. For example, signals from sensors that may include, but may not be limited to, a longitudinal acceleration sensor, a latitudinal acceleration sensor, a yaw sensor, and the like.
Referring now to
Combustion chamber 30 may receive intake air from intake manifold 44 via intake passage 42 and may exhaust combustion gases via exhaust passage 48. Intake manifold 44 and exhaust passage 48 can selectively communicate with combustion chamber 30 via respective intake valve 52 and exhaust valve 54. In some embodiments, combustion chamber 30 may include two or more intake valves and/or two or more exhaust valves.
In this example, intake valve 52 and exhaust valves 54 may be controlled by cam actuation via respective cam actuation systems 51 and 53. Cam actuation systems 51 and 53 may each include one or more cams and may utilize one or more of cam profile switching (CPS), variable cam timing (VCT), variable valve timing (VVT) and/or variable valve lift (VVL) systems that may be operated by controller 12 to vary valve operation. The position of intake valve 52 and exhaust valve 54 may be determined by position sensors 55 and 57, respectively. In alternative embodiments, intake valve 52 and/or exhaust valve 54 may be controlled by electric valve actuation. For example, cylinder 30 may alternatively include an intake valve controlled via electric valve actuation and an exhaust valve controlled via cam actuation including CPS and/or VCT systems.
Fuel injector 66 is shown coupled directly to combustion chamber 30 for injecting fuel directly therein in proportion to the pulse width of signal FPW received from controller 12 via electronic driver 68. In this manner, fuel injector 66 provides what is known as direct injection of fuel into combustion chamber 30. The fuel injector may be mounted in the side of the combustion chamber or in the top of the combustion chamber, for example. Fuel may be delivered to fuel injector 66 by a fuel delivery system (not shown) including a fuel tank, a fuel pump, and a fuel rail. In some embodiments, combustion chamber 30 may alternatively or additionally include a fuel injector arranged in intake passage 44 in a configuration that provides what is known as port injection of fuel into the intake port upstream of combustion chamber 30.
Intake passage 42 may include a throttle 62 having a throttle plate 64. In this particular example, the position of throttle plate 64 may be varied by controller 12 via a signal provided to an electric motor or actuator included with throttle 62, a configuration that is commonly referred to as electronic throttle control (ETC). In this manner, throttle 62 may be operated to vary the intake air provided to combustion chamber 30 among other engine cylinders. The position of throttle plate 64 may be provided to controller 12 by throttle position signal TP. Intake passage 42 may include a mass air flow sensor 120 and a manifold air pressure sensor 122 for providing respective signals MAF and MAP to controller 12.
Ignition system 88 can provide an ignition spark to combustion chamber 30 via spark plug 92 in response to spark advance signal SA from controller 12, under select operating modes. Though spark ignition components are shown, in some embodiments, combustion chamber 30 or one or more other combustion chambers of engine 10 may be operated in a compression ignition mode, with or without an ignition spark.
Exhaust gas sensor 126 is shown coupled to exhaust passage 48. Sensor 126 may be any suitable sensor for providing an indication of exhaust gas air/fuel ratio such as a linear oxygen sensor or UEGO (universal or wide-range exhaust gas oxygen), a two-state oxygen sensor or EGO, a HEGO (heated EGO), a NOx, HC, or CO sensor.
Controller 12 is shown in
As described above,
Other sensors 205, i.e. sensor 2 through sensor n, may be configured to measure various aspects of the disposition of the vehicle 14 by measuring various disposition values, i.e. disposition value 2 through disposition value n. For example, one or more of the other sensors 205 may be a lateral acceleration sensor. The lateral acceleration sensor may be configured to measure the lateral acceleration of the vehicle 14. Additionally, as another example, a longitudinal acceleration sensor may be configured to measure the longitudinal acceleration of the vehicle 14. Without limitation, other sensors configured to measure other disposition values may be included.
The RSC 232 may be configured to adjust the various actuators 206 to maintain the vehicle 14 on the driver's intended course. The sensors 204 may measure various vehicle operating conditions, and may determine the intended course and the actual course of the vehicle. In response to a disparity between the intended course and actual course, the RSC 232 may actuate various mechanisms in the vehicle, allowing the vehicle to maintain the intended course. The mechanisms may include the brake mechanisms 224, 226, 228, and 230, and the throttle 62 (
In one specific example, the actual vehicle motion may be measured via a lateral acceleration, yaw, and/or wheel speed measurement. The intended course may be measured by a steering angle sensor that may be included with the sensors 204. The RSC 232 may take actions to correct under-steer or over-steer.
Alternatively, even when the vehicle is following a desired course, the RSC 232 may take corrective action to increase the vehicle's stability. For example, the RSC 232 may determine if one or more wheels of the vehicle may loose contact with the road due to an increase in lateral acceleration. If so, the RSC 232 may brake one or more wheels and/or decrease the power produced by the engine 10, and delivered to the wheels 216, 218, 220, and 222.
The vehicle inclination sensor 238 may be further configured to provide a second output signal 244 to an inclined surface control 246. The inclined surface control 246 may include a rollback control module 248, configured to prevent vehicle rollback and/or a downhill control module 250 configured to provide downhill control of the vehicle 14.
The rollback control 248 may be configured to receive the second output signal 244, and to provide a brake output signal 252 to the brake controller 236 to activate the brake mechanisms 224, 226, 228, and 230 for an amount of time, and/or an amount of brake pressure, sufficient for the engine 10 to exert enough torque to propel the vehicle 14 up an incline without any substantial rollback. The amount of time, and/or an amount of brake pressure, may be determined by the degree of inclination 240 as determined by the vehicle inclination sensor 238.
The downhill control module 250 may also be configured to receive the second output signal 244. The downhill control module 250 may also provide the brake output signal 252 to the brake controller 236 to activate the brake mechanisms 224, 226, 228, and 230 and/or to provide an engine control output signal 254 to the engine controller 12 to slow the vehicle when, for example, the vehicle inclination sensor 238 passes the second signal 244 that indicates the vehicle is on an incline greater than a predetermined value, and/or the wheel sensors 208, 210, 212, 214 indicates a vehicle speed greater than a predetermined speed.
Various embodiments may provide a system 200 for an engine propelled vehicle. The system 200 may include a vehicle inclination sensor 238 configured to detect an inclination of the vehicle 14 and to provide an inclination output signal 242 to a roll stability control 232. The roll stability control 232 may be configured to provide at least brake and throttle control to effect improved vehicle stability control. The vehicle inclination sensor 238 may also be further configured to provide the inclination output signal to prevent vehicle rollback or provide downhill control of the vehicle.
In various embodiments, two or more of the roll stability control system 332, the hill holding control system 348, and the downhill control system 350 may be integrated into a single controller. For example, all three of the roll stability control system 332, the hill holding control system 348, and the downhill control system 350 may be integrated into a single controller. In other embodiments all three of the roll stability control system 332, the hill holding control system 348, and the downhill control system 350 may be provided in separate controllers.
In some embodiments specific characteristics of the signal may be filtered using one or more band pass filters. In this way the same vehicle inclination sensor may be used for multiple purposes, and the signal from the common vehicle inclination sensor may be filtered in an efficient way to ensure the proper part of the signal is used respectively for inclined surface control, and for RSC.
In a second case the signal 244 may be passed through a low frequency band-pass filter 274 before being passed to the inclined surface control 246 to filter out signals above a predetermined frequency. Signals from the other sensors 205 may also be used by the inclined surface controller 246 to determine, or to be included in the determination of, the disposition of the vehicle. Other cases are also possible.
The method 400 may also include, as may have been determined at decision box 404, in the case wherein a rollover is possible, as may be determined at decision box 412, determining if a rollover is imminent, and wherein if a rollover is imminent then, at 414, implementing rollover mitigation measures.
In some embodiments the first actuator and the second actuator may be the same actuator. The actuators may be configured to actuate one or more brake mechanisms. In some embodiments, the vehicle acceleration sensor may be a longitudinal accelerometer.
The first actuator may be configured to reduce a rollover tendency of the vehicle. The method 500 may also include adjusting a third actuator during vehicle travel on a declined surface to limit acceleration of the vehicle.
In some embodiments, the adjusting a second actuator to maintain vehicle position may include applying a brake to wheels of the vehicle with a selected brake pressure based on a degree of inclination as indicated by the vehicle acceleration sensor. Also, or alternatively, in some embodiments, the adjusting a second actuator to maintain vehicle position may include applying a brake to wheels of the vehicle for a selected amount of time based on a degree of inclination as indicated by the vehicle acceleration sensor. Also, or alternatively, in some embodiments, the adjusting a second actuator to maintain vehicle position may include increasing engine torque based on a degree of inclination as indicated by the vehicle acceleration sensor.
In some embodiments the method 500 may also include filtering road noise from a signal from the vehicle acceleration sensor. In this way the signal from the vehicle acceleration sensor may more accurately reflect the relevant data for use by the particular control feature.
Note that the example controls and routines included herein can be used with various engine and/or vehicle system configurations. The specific routines described herein may represent one or more of any number of processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. As such, various acts, operations, or functions illustrated may be performed in the sequence illustrated, in parallel, or in some cases omitted. Likewise, the order of processing is not necessarily required to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. One or more of the illustrated acts or functions may be repeatedly performed depending on the particular strategy being used. Further, the described acts may graphically represent code to be programmed into the computer readable storage medium in the engine control system.
It will be appreciated that the configurations and routines disclosed herein are exemplary in nature, and that these specific embodiments are not to be considered in a limiting sense, because numerous variations are possible. The subject matter of the present disclosure includes all novel and nonobvious combinations and subcombinations of the various systems and configurations, and other features, functions, and/or properties disclosed herein.
The following claims particularly point out certain combinations and subcombinations regarded as novel and nonobvious. These claims may refer to “an” element or “a first” element or the equivalent thereof. Such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and/or properties may be claimed through amendment of the present claims or through presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, also are regarded as included within the subject matter of the present disclosure.
