Patent Application
20190024595
The invention relates generally to a cylinder deactivation strategy based on telematics and connectivity or in combination with parameters associated with autonomous driving.
Current internal combustion engine cylinder deactivation strategies are primarily based on the requested propulsion torque at the current vehicle operating conditions, and are used to improve fuel economy. Internal combustion engines have an order in which each piston located in each cylinder is scheduled for firing. In using a cylinder deactivation strategy, cylinders are either scheduled for combustion or deactivation, depending on the engine torque demand, NVH (noise, vibration and harshness), and vehicle/engine constraints. This approach applies to conventional fixed-mode cylinder deactivation systems (e.g., changing between eight active cylinders and four active cylinders, or changing between four active cylinders and two active cylinders), or multi-mode cylinder deactivation systems, in which any number of cylinders in a given engine cycle can be deactivated or fired to meet the engine load demand. In all of these systems, future knowledge of the vehicle operating conditions or vehicle environment is not accounted for or included when scheduling cylinder deactivation (or individual cylinder firings). This typically leads to a suboptimal powertrain fuel efficiency improvement. This is particularly true if frequent changes in the required engine load demand and changes in the upcoming vehicle driving conditions lead to unnecessary cylinder deactivations or potentially poor system response when attempting to reactivate (i.e., fire) some or all of the engine cylinders. A vehicle utilizing engine cylinder deactivation for fuel efficiency gains may encounter these drawbacks in various situations, including, but not limited to: heavy traffic driving, traffic light approaches, road curvatures, road grades, and general vehicle deceleration.
One example of these drawbacks may occur where a vehicle is driven on a road with one or more curvatures. In this instance, a typical engine cylinder deactivation strategy frequently deactivates and reactivates the cylinders as the driver tips in and out (i.e., applies and releases) the accelerator and brake pedals while negotiating a curve. This is to be expected in a conventional cylinder deactivation strategy as current engine load demand changes. This irregular engine cylinder deactivation, or “hunting,” may have a negative effect on drivability and fuel efficiency/emissions. One reason these negative effects occur is that as cylinders are fired for reactivation, in particular for a fixed-mode cylinder deactivation system (e.g., changing from eight cylinders to four cylinders, and vice versa), ignition retard is typically used to prevent engine torque surges during the cylinder reactivation. In some engine cylinder deactivation strategies, deactivation hunting is prevented by means of an engine deactivation inhibit hysteresis logic, which prevents further deactivations when the time since the last deactivation was too short. This may lead to fuel efficiency gains that are not realized, since the cylinder deactivation becomes inhibited while preventing hunting.
Accordingly, there exists a need for an optimized engine cylinder deactivation strategy which improves fuel efficiency based on either or both of a combination of vehicle telematics and autonomous driving strategies.
In one embodiment, the present invention is an optimized engine cylinder deactivation strategy using connected energy management with advanced telematics including both static and dynamic data. In another embodiment, the present invention is an optimized engine cylinder deactivation strategy using connected energy management with autonomous driving strategies. In yet another embodiment, the present invention is an optimized engine cylinder deactivation strategy using connected energy management with advanced telematics including both static and dynamic data in combination with autonomous driving strategies.
If the engine controller (or powertrain controller) receives the current requested vehicle propulsion demand (torque or acceleration) and future vehicle propulsion demand, engine cylinder deactivation may be scheduled for ideal engine fuel efficiency. This allows the energy management strategy to maximize and extend the duration of engine cylinder deactivation operation, including vehicle cruising, passing, freeway entering/exiting maneuvers, etc. By having knowledge of the future vehicle acceleration/deceleration demand, the future engine load demand may be predicted and used to extend the duration of engine cylinder deactivation operation or alternatively modify the degree or level of engine cylinder deactivation (e.g. four-cylinder to six-cylinder operation on an eight-cylinder application) in order to meet the target vehicle trajectory set by the autonomous driving controller.
In an embodiment, the present invention is a connected energy management (CEM) system, which includes a strategy for controlling the activation of a plurality of engine cylinders in the engine of a vehicle. The CEM strategy is used with an engine having a plurality of cylinders, where a powertrain controller is operable for controlling the operation of the engine. A second controller is in electrical communication with the powertrain controller. In one embodiment, the second controller is a telematics controller, and in another embodiment, the second controller is an autonomous driving vehicle controller.
The second controller communicates at least one parameter to the powertrain controller, and the parameter is used to determine which of the plurality of cylinders are to be activated or deactivated. The powertrain controller then activates or deactivates one or more of the plurality of cylinders using the powertrain controller based on the parameter.
In the embodiment where a telematics controller is used, the parameter may be several parameters that include road data, such as both dynamic and static data. The static and dynamic data may include several different types of data, including, but not limited to, road curve shape, road grade, road surface, speed limits, traffic light data, vehicle traffic data, and vehicle accidents.
The vehicle includes an accelerator pedal and a brake pedal used for accelerating and decelerating the vehicle. The accelerator pedal is in electrical communication with the powertrain controller, and the desired load of the engine is controlled using the accelerator pedal, such that the load on the engine is changed based on the position of the accelerator pedal as detected by the powertrain controller. When incorporating the CEM strategy according to an embodiment of the present invention, one or more of the cylinders is activated or deactivated based on the at least one parameter, which may occur while propulsion torque is being requested (i.e., the driver is still applying force to the accelerator pedal). More specifically, when the driver of the vehicle has applied force to either the brake pedal or the accelerator pedal, the powertrain controller may activate or deactivate one or more of the cylinders to optimize efficiency of the engine.
In one embodiment, the CEM strategy may include a feedback mechanism which is used to communicate to the driver of the vehicle that the powertrain controller has activated or deactivated one or more of the plurality of cylinders, which may occur while the driver is still applying force to the accelerator pedal. In one embodiment, the feedback mechanism is a force-feedback accelerator pedal actuator, which works in opposition to the force applied to an accelerator pedal by the driver of the vehicle. In another embodiment, the feedback mechanism is an alert, which informs the driver of the vehicle that the powertrain controller has activated or deactivated one or more of the plurality of cylinders.
In the embodiment where the second controller is an autonomous driving vehicle controller, the parameter may be multiple parameters, including, but not limited to a current requested vehicle propulsion torque, and a future requested vehicle propulsion torque based on a target vehicle trajectory, such as a desired autonomous driving path. The powertrain controller activates or deactivates one or more of the plurality of cylinders based on the current requested vehicle propulsion torque and the future requested vehicle propulsion torque. More specifically, the autonomous driving vehicle controller communicates a plurality of data points to the powertrain controller. The plurality of data points represents the magnitude of the at least one parameter at a current time, and at least one future time. The powertrain controller activates or deactivates one or more of the cylinders using the data points at both the current time and the at least one future time to optimize efficiency such that the vehicle achieves the target vehicle trajectory (i.e., navigates the desired autonomous driving path).
The target vehicle trajectory may be used to predict the load demand on the engine based on the current requested vehicle propulsion torque and the future requested vehicle propulsion torque.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.
The present invention is an optimized engine cylinder deactivation strategy using connected energy management and autonomous driving strategies. Referring to
The autonomous driving system 10 having the CEM strategy of the present invention expands the interface between the powertrain system of the vehicle and the autonomous driving controller 12, such that data received by both the autonomous driving vehicle controller 12 and the powertrain controller 14 may be used to provide for a more accurate CEM strategy for the vehicle, and potentially changes the operating state of one or more of the cylinders of the engine 32C at both a current operating time, in addition to multiple points in time in the future, to optimize the CEM strategy.
In one embodiment, the autonomous driving system 10 using a CEM strategy for cylinder deactivation applies to a vehicle with advanced telematics using the road data 30, including both static and dynamic data around the vehicle including, but not limited to: road map database data (curves, grades, surface, speed limits, etc), and dynamic road events (traffic light real-time data, vehicle traffic data per lane, vehicle accidents, etc.). The road data 30 may be obtained using some type of device, such as a telematics controller 14A, which is in communication with the powertrain controller 14, with examples of road data 30 obtained by the telematics controller 14A shown in at 30A in
An example of an approach using a CEM strategy for engine cylinder deactivation using parameters which include road data 30, such as dynamic traffic light data information, according to the first embodiment of the present invention is shown in
Typically, with regard to a conventional engine cylinder deactivation, the deactivation is not scheduled until vehicle deceleration begins as the driver begins to release the accelerator pedal (i.e., “tips out”), and ultimately brakes, as the traffic light signal 40 is approached. The distance the vehicle has travelled while one or more of the engine cylinders has been deactivated (using a conventional cylinder deactivation strategy) is shown at 42.
The CEM strategy of the present invention involves triggering engine cylinder deactivation over a larger distance 44 by utilizing dynamic traffic light data 30A obtained by the telematics controller 14A. The traffic light signal 40 is shown with the green light illuminated shown at 40A, and the red light illuminated at 40B. The amount of time between the green light being illuminated and the red light being illuminated is communicated to the vehicle 34. In the example shown in
In an alternate embodiment, another type of feedback mechanism, such as a force-feedback accelerator pedal actuator 14B is included and controlled by the powertrain controller 14. The force-feedback accelerator pedal actuator 14B works in opposition to the force applied to the accelerator pedal by the driver of the vehicle 34. Earlier cylinder deactivation is initiated by the powertrain controller 14 through the use of the force-feedback accelerator pedal actuator 14B to communicate to the driver to stop application of the accelerator pedal. This is possible since vehicle deceleration up to the intersection 38 is predicted by the powertrain controller 14 by using the road data 30 and dynamic traffic light data 30A.
In another alternate embodiment, it is within the scope of the invention that in the example shown in
The vehicle 34 incorporating another example of the CEM strategy according to the first embodiment of the present invention is shown in
Because the vehicle 34 includes the autonomous driving system 10 which uses the CEM strategy of the present invention, one of the parameters detected is the upcoming curves of the road 46, represented by the road curve zone 58 (which the vehicle 34 travels between time t1 and time t2), and various cylinders of the engine 32C are activated and deactivated as the vehicle 34 travels the road 46 without frequent hunting. The engine 32C has eight cylinders, and in the example shown in
In comparison, the cylinder activation/deactivation 56 of a vehicle which does not incorporate the CEM strategy of the present invention is shown in
One of the advantages of implementing the CEM strategy of the present invention is that the average engine load demand is anticipated throughout the various curves of the road 46 (i.e., the road curve zone 58) such that cylinder deactivation is optimized without frequent hunting. This leads to overall fuel efficiency gains as the curves of the road 46 are navigated. Unnecessary cylinder deactivations/reactivations and corresponding torque surges are reduced or eliminated. This CEM strategy according to the present invention, which anticipates the road curvature or crossing detection, is not limited to a fixed-mode cylinder deactivation system, but also applies to any multi-mode cylinder deactivation system in which one or more cylinders may be fired or reactivated in any given engine cycle.
In another embodiment, it is within the scope of the invention that in the example shown in
A second embodiment of the present invention is shown in
The graphs in
As the vehicle 34 is moving on the road 64, the autonomous driving vehicle controller 12 determines the autonomous driving path 66 necessary for the passing maneuver to be performed. During the first phase 60A, the vehicle 34 is travelling at a substantially constant speed, and both the target vehicle acceleration 70 and actual measured vehicle acceleration 72 are substantially zero. The engine load demand 74 is also substantially constant, and the vehicle 34 is operating in the first mode of operation, where four cylinders are active. The autonomous driving vehicle controller 12 predicts and calculates the target acceleration 70 within a predictive engine load demand window 80, where the window 80 includes the target vehicle acceleration 70 needed to perform the entire passing maneuver, based on both the current requested vehicle propulsion torque, which occurs at the current time t1, and future requested propulsion torque, which occurs at a future time, such that the vehicle 34 achieves the target vehicle acceleration 70. The future time may occur at any point in time between t1 and tY in the predictive engine load demand window 80. The window 80 is broken up incrementally into a plurality of data points representing the various parameters, such that any number of data points may be used between times t1 and tY as the future time.
As mentioned above, the graphs in
The vehicle 34 begins to perform the passing maneuver beginning in the second phase 60B, where the engine load demand 74 increases, as the vehicle 34 accelerates and increases speed. It is shown in
Once the vehicle 34 has been accelerated to the target vehicle speed 68 to pass the second vehicle 62B, the vehicle 34 then remains at a substantially constant speed in the third phase 60C, such that the engine 32C is switched back to the first mode of operation, where only four cylinders are active.
After the vehicle 34 has passed the second vehicle 62B, the vehicle 34 is then decelerated during the fourth phase 60D. During the fourth phase 60D, since the vehicle 34 is being decelerated, the engine load demand 74 decreases during the fourth phase 60D, and is negative for a period of time. Because the engine load demand 74 is so low during the fourth phase 60D, the powertrain controller 14 changes the engine 32C to a third mode of operation, where none of the cylinders are active, the intake valves and exhaust valves are closed, and there is no fueling, reducing fuel consumption. During most of the fourth phase 60D, the engine 34 is operating in the third mode of operation, where no cylinders are active. In an alternate embodiment, during the fourth phase 60D, engine braking may be maximized by changing the engine 32C to the second mode of operation, where all eight cylinders are active, there is no fueling, and the intake valves and exhaust valves are open. This is typical deceleration fuel cut-off, and such that engine braking is used to gently decelerate the vehicle 34.
During the end of the fourth phase 60D, and knowing that a constant vehicle speed is then to be maintained after completion of the passing maneuver (in the fifth phase 60E), the CEM strategy of the present invention includes changing the engine 32C back to the first mode of operation, where only four cylinders are active because in the fifth phase 60E the target vehicle acceleration 70 in the future requested from the autonomous driving vehicle controller 12 is zero (i.e, zero acceleration). Once the vehicle 34 has completed the passing maneuver, and has completed deceleration, the vehicle 34 returns to travelling at a constant speed in the fifth phase 60E. The powertrain controller 14 maintains the operation of the engine 32C in the first mode of operation, where four cylinders are active.
In further regard to the CEM strategy according to the present invention, at time t0, the current and future engine load demand 74 (between times t1 and tY) is calculated based on the desired autonomous driving path 66 (and corresponding parameters including vehicle acceleration/deceleration or propulsion torque requests, as well as both the target vehicle speed 68 and target vehicle acceleration 70) provided by the autonomous driving vehicle controller 12. The CEM engine cylinder deactivation strategy of the present invention schedules the engine 32C to operate in the second mode of operation (all eight cylinders active) toward the end of the first phase 60A and during the second phase 60B in preparation to meet the required torque demand and target vehicle acceleration 70 needed for the vehicle 34 to perform the passing maneuver. At the beginning of the third phase 60C, vehicle longitudinal acceleration is no longer requested as the vehicle 34 is then passing at a constant speed, and ultimately the engine load demand 74 decreases, where the engine 32C is changed back to the first mode of operation, such that four cylinders are active. Unlike the non-CEM (conventional) cylinder deactivation approach, knowing the data points for each of the parameters, including the propulsion torque demand for the entire predictive engine load demand window 80, allows for a more optimized cylinder deactivation operating strategy.
As shown in
This is in contrast to when the CEM strategy of the present invention is not used, where as shown by the indication of active cylinders 78, the powertrain controller 14 does not change the engine 32C from the first mode of operation to the second mode of operation until after t1 in the second phase 60B, and switches to the third mode of operation after time t3 in the fourth phase 60D. The engine 32C does not revert back to the first mode of operation until during the fifth phase 60E (after time t4).
In
Furthermore, when comparing the indication of active cylinders 78 (which does not use the CEM strategy of the present invention) to the indication of active cylinders 76 (which incorporates the CEM strategy of the present invention), it is shown by that there is a lag when changing from the first mode of operation to the second mode of operation near time t1. The indication of active cylinders 78 also shows the change from the second mode of operation directly to the third mode of operation after time t3 in the fourth phase 60D, which is different from the indication of active cylinders 76, which transitions to back to the first mode of operation during the third phase 60C, instead of remaining in the second mode of operation during the third phase 60C. The indication of active cylinders 78 indicates the engine 32C remains in the second mode of operation for a longer period of time, increasing fuel consumption, and reducing efficiency. There is another lag when changing from the third mode of operation back to the first mode of operation around time t4. Furthermore, when the CEM strategy of the present invention is not used, the vehicle 34 may not perform the passing maneuver as desired, or reach the target vehicle acceleration 70, because of the lag which occurs when changing between the first mode of operation (four cylinder active) and the second mode of operation (eight cylinders active). Using the CEM strategy of the present invention provides a more optimized use of available engine torque.
While the example shown in
In another embodiment, it is within the scope of the invention that in the example shown in
The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.
This application claims the benefit of U.S. Provisional Application No. 62/462,408 filed Feb. 23, 2017. The disclosure of the above application is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62462408 | Feb 2017 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15597791 | May 2017 | US |
| Child | 16137058 | US |
