The present disclosure relates to vehicles having powertrains that include engines, and control systems for such powertrains.
Vehicles may include engines that are configured to generate power and deliver the power to one or more drive wheels.
An internal combustion engine system includes a first bank of cylinders, a second bank of cylinders, an exhaust system, a first exhaust gas sensor, a second exhaust gas sensor, a third exhaust gas sensor, and a fourth exhaust gas sensor. The first bank of cylinders has first and second sets of cylinders. The second bank of cylinders has third and fourth sets of cylinders. The exhaust system has primary conduits, secondary conduits branching from the primary conduits, and tertiary conduits branching from the secondary conduits. A first of the secondary conduits extends from a first of the primary conduits and branches into corresponding tertiary conduits that each connect to the first set of cylinders. A second of the secondary conduits extends from the first of the primary conduits and branches into corresponding tertiary conduits that connect to the second set of cylinders. A third of the secondary conduits extends from a second of the primary conduits and branches into corresponding tertiary conduits that connect to the third set of cylinders. A fourth of the secondary conduits extends from the second of the primary conduits and branches into corresponding tertiary conduits that connect to the fourth set of cylinders. The first, second, third, and fourth exhaust gas sensors are disposed within the first, second, third, and fourth secondary conduits, respectively, and are configured to measure air-to-fuel ratios of the first, second, third, and fourth sets of cylinders, respectively.
An internal combustion engine system includes a first bank of cylinders, a second bank of cylinders, a first exhaust manifold, a second exhaust manifold, and exhaust gas sensors. The first bank of cylinders has first and second pairs of cylinders. The second bank of cylinders has third and fourth pairs of cylinders. The first exhaust manifold is disposed between the first bank of cylinders and a first catalyst. The first exhaust manifold has a first primary conduit extending from the first catalyst; first and second secondary conduits branching from the first primary conduit; first and second tertiary conduits branching from the first secondary conduit and connected to the first pair of cylinders; and third and fourth tertiary conduits branching from the second secondary conduit and connected to the second pair of cylinders. The second exhaust manifold is disposed between the second bank of cylinders and a second catalyst. The second exhaust manifold has a second primary conduit extending from the second catalyst; third and fourth secondary conduits branching from the second primary conduit; fifth and sixth tertiary conduits branching from the third secondary conduit and connected to the third pair of cylinders; and seventh and eighth tertiary conduits branching from the fourth secondary conduit and connected to the fourth pair of cylinders. The exhaust gas sensors are disposed within each of the first, second, third, and fourth secondary conduits and are configured to measure air-to-fuel ratios of the first, second, third, and fourth pairs of cylinders.
An internal combustion engine system includes a first set of cylinders, a second set of cylinders, exhaust manifolds, and exhaust gas sensors. The first set of cylinders has first and second subsets of cylinders. The second set of cylinders has third and fourth subsets of cylinders. The exhaust manifolds have primary conduits, secondary conduits branching from the primary conduits, and tertiary conduits branching from the secondary conduits. The tertiary conduits associated with each of the secondary conduits are connected to one of the first, second, third, or fourth subsets of cylinders. The exhaust gas sensors are disposed within each of the secondary conduits and are each configured to measure air-to-fuel ratios of one of the first, second, third, or fourth subsets of cylinders.
Embodiments of the present disclosure are described herein. It is to be understood, however, that the disclosed embodiments are merely examples and other embodiments may take various and alternative forms. The figures are not necessarily to scale; some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the embodiments. As those of ordinary skill in the art will understand, various features illustrated and described with reference to any one of the figures may be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular applications or implementations.
Referring to
The engine 14 may be connected to an input shaft of the transmission by a torque converter 19 or a launch clutch while an output shaft of the transmission 16 may be connected to a driveshaft 22. The driveshaft 22 may then be connected to a rear drive unit (RDU) 24. The RDU 24 may then be connected to the drive wheels 18 by half shafts 26. The RDU 24 may include a differential and/or one more clutches to control the power output to the wheels 18.
The torque converter 19 includes an impeller 21 fixed to the crankshaft of the engine 14, a turbine 23 fixed to an input shaft to the transmission 16, and a stator 25 that is grounded such that it does not rotate. The torque converter 19 thus provides a hydraulic coupling between the crankshaft of the engine 14 and the input shaft to the transmission 16. The torque converter 19 transmits power from the impeller to the turbine when the impeller rotates faster than the turbine. The magnitude of the turbine torque and impeller torque generally depend upon the relative speeds. When the ratio of impeller speed to turbine speed is sufficiently high, the turbine torque is a multiple of the impeller torque. A torque converter bypass clutch (also known as a torque converter lock-up clutch) 27 may also be provided that, when engaged, frictionally or mechanically couples the impeller and the turbine of the torque converter 19, permitting more efficient power transfer. The torque converter bypass clutch 27 may be configured to transition between an opened (or disconnected) state, a closed (or locked) state, and a slipping state. The rotation of the impeller 21 and the turbine 23 are synchronized when the torque converter bypass clutch 27 is in the closed or locked state. The rotation of the impeller 21 and the turbine 23 are non-synchronized when the torque converter bypass clutch 27 is in the opened state or the slipping state.
The transmission 16 may include gear sets (not shown) that are selectively placed in different gear ratios by selective engagement of friction elements such as clutches to establish the desired multiple discrete or step drive ratios. More specifically, the transmission 16 may have a plurality of clutches 30 configured to shift the transmission 16 between a plurality of gear ratios. The friction elements are controllable through a shift schedule that connects and disconnects certain elements of the gear sets to control the ratio between a transmission output shaft (e.g., driveshaft 22) and the transmission input shaft (e.g., a shaft connected to the crankshaft of the engine 14). The transmission 16 is automatically shifted from one ratio to another based on various vehicle and ambient operating conditions by an associated controller, such as a powertrain control unit (PCU). Power and torque from the engine 14 may be delivered to and received by transmission 16. The transmission 16 then provides powertrain output power and torque to driveshaft 22.
The various components of the powertrain 12, including the output shaft of the transmission 16, driveshaft 22, RDU 24, half shafts 26, wheels 18, may be connected to each other, as described above, via constant-velocity joints 38. Constant-velocity joints connect two rotating parts and allow the two rotating parts to rotate about different axes.
Although
The powertrain 12 further includes an associated controller 40 such as a powertrain control unit (PCU). While illustrated as one controller, the controller 40 may be part of a larger control system and may be controlled by various other controllers throughout the vehicle 10, such as a vehicle system controller (VSC). It should therefore be understood that the powertrain control unit 40 and one or more other controllers can collectively be referred to as a “controller” that controls various actuators in response to signals from various sensors to control functions such as starting/stopping engine 14, select or schedule transmission shifts, etc. Controller 40 may include a microprocessor or central processing unit (CPU) in communication with various types of computer readable storage devices or media. Computer readable storage devices or media may include volatile and nonvolatile storage in read-only memory (ROM), random-access memory (RAM), and keep-alive memory (KAM), for example. KAM is a persistent or non-volatile memory that may be used to store various operating variables while the CPU is powered down. Computer-readable storage devices or media may be implemented using any of a number of known memory devices such as PROMs (programmable read-only memory), EPROMS (electrically PROM), EEPROMs (electrically erasable PROM), flash memory, or any other electric, magnetic, optical, or combination memory devices capable of storing data, some of which represent executable instructions, used by the controller in controlling the engine or vehicle.
The controller communicates with various engine/vehicle sensors and actuators via an input/output (I/O) interface (including input and output channels) that may be implemented as a single integrated interface that provides various raw data or signal conditioning, processing, and/or conversion, short-circuit protection, and the like. Alternatively, one or more dedicated hardware or firmware chips may be used to condition and process particular signals before being supplied to the CPU. As generally illustrated in the representative embodiment of
Control logic or functions performed by controller 40 may be represented by flow charts or similar diagrams in one or more figures. These figures provide representative control strategies and/or logic that may be implemented using one or more processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. As such, various steps or functions illustrated may be performed in the sequence illustrated, in parallel, or in some cases omitted. Although not always explicitly illustrated, one of ordinary skill in the art will recognize that one or more of the illustrated steps or functions may be repeatedly performed depending upon the particular processing strategy being used. Similarly, the order of processing is not necessarily required to achieve the features and advantages described herein, but is provided for case of illustration and description. The control logic may be implemented primarily in software executed by a microprocessor-based vehicle, engine, and/or powertrain controller, such as controller 40. Of course, the control logic may be implemented in software, hardware, or a combination of software and hardware in one or more controllers depending upon the particular application. When implemented in software, the control logic may be provided in one or more computer-readable storage devices or media having stored data representing code or instructions executed by a computer to control the vehicle or its subsystems. The computer-readable storage devices or media may include one or more of a number of known physical devices which utilize electric, magnetic, and/or optical storage to keep executable instructions and associated calibration information, operating variables, and the like.
An accelerator pedal 42 is used by the driver of the vehicle to provide a desired or demanded torque, power, or drive command to propel the vehicle. In general, depressing and releasing the accelerator pedal 42 generates an accelerator pedal position signal that is representative of an accelerator pedal position and may be interpreted by the controller 40 as a demand for increased power or decreased power, respectively, or as a demand for increased torque or decreased torque, respectively. A brake pedal 44 is also used by the driver of the vehicle to provide a demanded braking torque to slow the vehicle. The brake pedal 44 may configured to actuate friction brakes 46 to slow the vehicle through a hydraulic, electrical, or other system when applied. In general, depressing and releasing the brake pedal 44 generates a brake pedal position signal that may be interpreted by the controller 40 as a demand to decrease the vehicle speed. Based upon inputs from the accelerator pedal 42 and brake pedal 44, the controller 40 commands the torque to the engine 14 and friction brakes 46. The controller 40 also controls the timing of gear shifts within the transmission 16 based on one or more shift schedules that may be stored as tables within the controller. The shift schedules may be based on a demanded torque or power output via the accelerator pedal and a speed of the vehicle.
It should be understood that the vehicle configuration described herein is merely exemplary and is not intended to be limited. Other non-hybrid or hybrid vehicle configurations should be construed as disclosed herein. Other vehicle configurations may include, but are not limited to, micro-hybrid vehicles, series hybrid vehicles, parallel hybrid vehicles, series-parallel hybrid vehicles, plug-in hybrid electric vehicles (PHEVs), or any other vehicle configuration known to a person of ordinary skill in the art.
Referring to
The upper graphs in
More specifically, in the example of
As the exhaust gas sensor exposure period to the exhaust pulse from the imbalanced cylinder (i.e., residency time) is increased from ⅛ (or) 90° to ⅜ (270°) to ½ (360°) of an engine cycle, the resulting measured amplitude of λ oscillation for the same 20% lean imbalance (black dash-sotted traces) increases from ≈0.022 to ≈0.046 to ≈0.049. Therefore, the longer period of exposure (i.e., longer residency time) allows the more time for exhaust gas sensor to react to the imbalanced cylinder resulting in a gradual increase in measured λ and larger λ oscillations. The bottom plots also show steeper curves and therefore stronger signals for an imbalance when the exposure of the imbalanced cylinder increases.
However, increasing the exhaust gas sensor period of exposure to the imbalanced cylinder beyond ½ (360°) of an engine cycle reduces the measured amplitude of λ oscillations. While this non-monotonic behavior may seem counter intuitive at first, the air-to-fuel ratio imbalance is a relative metric: one cylinder air-to-fuel ratio relative to the remaining cylinders' air-to-fuel ratios (measured by the same exhaust gas senor sensor). A reduced period of exposure to either the imbalanced cylinder or the remaining cylinders reduces the λ oscillation amplitude. It is noted that the amplitude of λ oscillations corresponding to exhaust pulses spanning ⅛ and ⅞ of an engine cycle at the exhaust sensor (i.e., residency times are ⅛ and ⅞ of cycle) are the same, and the amplitude of λ oscillations corresponding to exhaust pulses spanning ⅜ and ⅝ of an engine cycle the exhaust sensor (i.e., residency times are ⅜ and ⅝ of cycle) are the same. Therefore, a first cylinder with an exhaust pulse spanning a fraction (f) of an engine cycle (at the exhaust sensor) and a second cylinder with an exhaust pulse spanning 1-f of an engine cycle (at the exhaust sensor) would achieve a similar-strength λ oscillation amplitude correspond to a signal of an air-to-fuel ratio imbalance between cylinders.
Referring to
resulting higher amplitude λ oscillations and a stronger imbalance signal (e.g., upper V-shaped graph in
In order to have a capable and reliable air-fuel ratio imbalance monitor (AFRIM), all the oscillation signals due to nominal air-to-fuel ratio imbalances (e.g., +5%) should fall below a detection threshold to evade false positives and all the oscillations signals due to fault imbalances (e.g., +15%) should fall above the detection threshold to evade false negatives and remain within a desired emissions range. In the example in
Referring to
The internal combustion engine system 100 includes an air intake or intake manifold 113 and an exhaust system 114. The exhaust system 114 has primary conduits 116; secondary conduits 118 branching and extending from the primary conduits 116; and tertiary conduits 120 branching and extending from the secondary conduits 118. More specifically, the exhaust system 114 may include a first exhaust manifold 122 and a second exhaust manifold 124 that include the primary conduits 116, secondary conduits 118, and tertiary conduits 120. The first exhaust manifold 122 is disposed between and connected to each of the first bank of cylinders 102 and a first catalyst 126. The second exhaust manifold 124 is disposed between and connected to each the second bank of cylinders 104 and a second catalyst 128. The first catalyst 126 and the second catalyst 128 may be configured to filter CO gases, NOx gases, and unspent hydrocarbons from the exhaust.
The first exhaust manifold 122 includes: a first of the primary conduits 116 extending from the first catalyst 126; a first and a second of the secondary conduits 118 that each branch from the first of the primary conduits 116; a first and a second of the tertiary conduits 120 branching from the first of the secondary conduits 118 and connected to the first set of cylinders 106; and a third and a fourth of the tertiary conduits 120 branching from the second of the secondary conduits 118 and connected to the second set of cylinders 108. The second exhaust manifold 124 includes: a second of the primary conduits 116 extending from the second catalyst 128; a third and a fourth of the secondary conduits 118 that each branch from the second of the primary conduits 116; a fifth and a sixth of the tertiary conduits 120 branching from the third of the secondary conduits 118 and connected to the third set of cylinders 110; and a seventh and an eighth of the tertiary conduits 120 branching from the fourth of the secondary conduits 118 and connected to the fourth set of cylinders 112.
Exhaust gas sensors 130 may be disposed within each of the secondary conduits 118. The exhaust gas sensors 130 may include first, second, third, and fourth exhaust gas sensors 130 that are configured to measure air-to-fuel ratios of the first, second, third, and fourth sets of cylinders, 106, 108, 110, and 112, respectively, and relay or communicate the air-to-fuel ratios of the first, second, third, and fourth sets of cylinders, 106, 108, 110, and 112, respectively, to the controller 40. The exhaust gas sensors 130 may be UEGO sensors. The secondary conduits 118 are segregated upstream of the corresponding primary conduit 116 and catalyst (e.g., first catalyst 126 and second catalyst 128) so that the exhaust from each set of cylinders (e.g., first, second, third, and fourth sets of cylinders, 106, 108, 110, and 112) is not mixed with the exhaust from the other sets of cylinders along the placement positions of the exhaust gas sensors 130.
The internal combustion engine system 100 includes a firing order where the cylinders within each set of cylinders (e.g., first, second, third, and fourth sets of cylinders, 106, 108, 110, and 112) are separated by a firing order that is at least 270° (⅜ of a single engine cycle), but is preferably between 270° (⅜ of a single engine cycle) and 450° (⅝ of a single engine cycle) so that there is a strong oscillation signal if there is an air-to-fuel ratio discrepancy or imbalance between the cylinders within one of the sets of cylinders (e.g., first, second, third, and fourth sets of cylinders, 106, 108, 110, and 112). For example, the cylinders may be labelled 1-8 and the firing order may be 1-3-7-2-6-5-4-8, as shown in
Referring to
Referring to
Next, the method 200 moves to block 204 where the air-to-fuel ratios of the cylinders of the internal combustion engine system 100 are monitored via the exhaust gas sensors 130. Next, the method 200 moves onto block 206 where it is determined (i) if an oscillation in the measured air-to-fuel ratios of the cylinders within one or more of the sets of cylinders (e.g., the cylinders within the first, second, third, or fourth sets of cylinders, 106, 108, 110, or 112) detected by the corresponding exhaust gas sensor 130 exceeds a threshold or (ii) if a difference a difference or an absolute value of a difference between average values of the air-to-fuel ratios between different sets of cylinders (e.g., the first, second, third, or fourth sets of cylinders, 106, 108, 110, and 112) over a predetermined period of time is greater a threshold. Optionally, the second portion of block 206 may only consider if the difference between the average values of the air-to-fuel ratio between the different sets of cylinders is greater than the threshold within a common bank of cylinders (e.g., the first bank of cylinders 102 and the second bank of cylinders 104).
If the answer at block 206 is NO, the method 200 returns to block 204 and continues to monitor the air-to-fuel ratios of the cylinders of the internal combustion engine system 100. If the answer at block 206 is YES, the method 200 moves on to block 208 where the controller 40 issues a fault due to an air-to-fuel ratio imbalance between the cylinders of the internal combustion engine system 100. The fault may include illuminating a light on a control panel, providing audible feedback, providing haptic feedback, etc. It should be understood that the flowchart in
Referring to
The method 300 moves to block 304 where the air-to-fuel ratios of the cylinders of the internal combustion engine system 100 are monitored via the exhaust gas sensors 130. Next, the method 300 moves on to block 306 where the air-fuel-ratio commands or air-fuel ratio feedback corrections to each of the sets of cylinders (e.g., the first, second, third, or fourth sets of cylinders, 106, 108, 110, or 112) are generated based on the air-fuel-ratios monitored or measured at block 304. The method 300 then moves onto block 308 where it is determined if a difference of an absolute value of a difference between the air-to-fuel ratio commands or air-fuel ratio feedback corrections between the sets of cylinders (e.g., the first, second, third, or fourth sets of cylinders, 106, 108, 110, or 112) exceeds a threshold. Other embodiments may compute an air-fuel ratio error as a difference between air-fuel ratio commands and (average values) of measured air-fuel ratios. At block 308, it is determined if a difference or an absolute value of a difference between the air-to-fuel ratio errors between the sets of cylinders (e.g., the first, second, third, or fourth sets of cylinders, 106, 108, 110, or 112) exceeds a threshold. Optionally, block 308 may only consider if the difference between the air-to-fuel ratios between sets of cylinders is within a common bank of cylinders (e.g., the first bank of cylinders 102 and the second bank of cylinders 104).
If the answer at block 308 is NO, the method 300 returns to block 304 and continues to monitor the air-to-fuel ratios of the cylinders of the internal combustion engine system 100. If the answer at block 308 is YES, the method 300 moves on to block 310 where the controller 40 issues a fault due to an air-to-fuel ratio imbalance between the cylinders of the internal combustion engine system 100. The fault may include illuminating a light on a control panel, providing audible feedback, providing haptic feedback, etc. It should be understood that the flowchart in
It should be understood that the designations of first, second, third, fourth, etc. for any component, state, or condition described herein may be rearranged in the claims so that they are in chronological order with respect to the claims. Furthermore, it should be understood that any component, state, or condition described herein that does not have a numerical designation may be given a designation of first, second, third, fourth, etc. in the claims if one or more of the specific component, state, or condition are claimed.
The words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments may be combined to form further embodiments that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics may be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. As such, embodiments described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and may be desirable for particular applications.