Patent Application
20180058413
The present disclosure relates to a no-start fault diagnostic method and system for use in a powertrain having a controller-enabled starter system.
Conventional powertrains typically include an internal combustion engine that uses reciprocating pistons disposed within corresponding engine cylinders to combust a mixture of fuel and air. The combustion process generates engine torque on a driveshaft, which in turn is delivered to a transmission via a hydrodynamic torque converter or a friction clutch. An output member of the transmission ultimately acts on a load. The load may be in the form of a set of drive wheels when the powertrain is used to power an automotive vehicle, or in the form of a propeller shaft, generator, conveyor, or another load in other powertrain configurations.
In order for the engine to start, an engine flywheel must be rotated from a standstill to above a threshold speed, with the threshold speed being sufficient for initiating an intake of the fuel/air mixture into the cylinders via a fuel delivery system. An operator may request an engine start event by depressing a start button or turning an ignition key, or such a request may be generated autonomously or remotely. The received request closes a solenoid control relay, which in turn causes an electrical current to be delivered to a starter solenoid.
The starter motor has a shaft on which is disposed a translatable pinion gear. The pinion gear is ultimately urged by a lever arm by operation of the starter solenoid into engagement with a mating gear element disposed on the engine flywheel. The starter motor gear is then energized so that torque from the starter motor rotates the engine via the engaged pinion gear and engine flywheel to the threshold speed noted above. Upon release of the ignition key or starter button, the solenoid control relay opens to disconnect the battery from the starter motor and starter solenoid. The starter motor stops and the pinion gear disengages from the flywheel. The internal combustion process is thereafter sustained via operation of the fuel delivery system.
A successful engine starting event thus occurs when a controller, e.g., an engine control module, enables the starter control relay via an electronic enable signal and, after passage of a calibrated duration, the engine starts. However, a “no-start” condition sometimes results even when the starter control relay has been properly enabled. While a faulty starter control relay may be the culprit for such a failure mode, other fault candidates exist, including a faulty battery, starter solenoid, starter motor, or power/grounding wire for the starter motor or solenoid. Other fault candidates include a faulty pinion gear or flywheel, engine, or fuel delivery system. However, conventional diagnostic approaches are typically unable to distinguish one fault mode from the other, which can complicate maintenance and repair efforts.
Disclosed herein are methods and related systems for performing no-start diagnostics in a powertrain having a controller-enabled starter control relay. As disclosed herein, the present approach utilizes a starting sequence to accurately isolate a no-start fault mode with an enabled starter control relay, and to execute different control actions based on the isolated fault mode.
In a particular embodiment, a method is disclosed for diagnosing a no-start condition in a powertrain having an engine fueled by a fuel delivery system and a starter system operable for starting the engine. The starter system includes a battery, a solenoid relay, a starter solenoid, and a starter motor, and is characterized in this embodiment by an absence of a current sensor configured to measure a maximum cranking current of the battery.
The method includes recording a set of starter data over a calibrated sampling duration in response to a requested start event when the solenoid relay is in an enabled state, including a cranking voltage and a speed of the engine, and deriving a resistance ratio using an open-circuit voltage and a minimum cranking voltage of the battery.
The method also includes identifying one of a plurality of different fault modes of the starter system via a controller using the set of starter data and the resistance ratio, and then executing a control action corresponding to the identified fault mode. Executing a control action may include recording a diagnostic fault code corresponding to the identified fault mode.
In another embodiment in which the intelligent battery sensor is used to measure a maximum cranking current, instead of deriving a resistance ratio as described above, the controller instead derives a battery resistance and a starter resistance using the open-circuit voltage, minimum cranking voltage, and a measured maximum cranking current of the battery.
A powertrain is also disclosed herein that, in an embodiment, includes an engine, a clutch, a transmission having an input member connectable to the engine via the clutch, a load connected to an output member of the transmission, a starter system operable for starting the engine, and a controller. The starter system has a battery and a solenoid relay, a starter solenoid, and a starter motor having a pinion gear. The pinion gear is selectively engaged with the flywheel via operation of the starter solenoid to start the engine. The controller is in communication with the starter system, and is configured to execute the method or methods noted above.
The above features and advantages and other features and advantages of the present disclosure are readily apparent from the following detailed description of the best modes for carrying out the disclosure when taken in connection with the accompanying drawings.
Referring to the drawings, wherein like reference numbers refer to the same or like components in the several Figures, a powertrain 10 is depicted schematically in
The transmission 12 has an input member 15 and an output member 16. The input member 15 is connectable to the engine 12 via the clutch C1, while a load, e.g., the drive wheels 17, a drive axle, or another load, is connected to the output member 16. In the example embodiment of
The powertrain 10 includes a starter system 18 operable for starting the engine 12. The starter system 18 includes a battery (B) 19, a starter control relay 20, a starter solenoid (SM) 22, and a starter motor (MS) 24. The starter motor 24 includes a pinion gear 26 that is selectively engaged with a flywheel 28 of the engine 12 via operation of the starter solenoid 22 to start the engine 12 as noted above. The powertrain 10 also includes a controller (C) 50 in the form of a group of controllers configured, i.e., programmed in software and equipped in hardware, to diagnose no-start faults of the powertrain 10 when the starter system 18 is enabled by a designated one of the controllers 50. For illustrative simplicity, the group of controllers 50 is shown and described herein in the singular. However, in practice the controller 50 may include multiple control devices each performing designated control functions as described herein.
Each noted control module described below includes a processor (P) and memory (M), which similarly are shown as one device without limiting embodiments to such a configuration. The memory (M) includes tangible, non-transitory memory, e.g., read only memory, whether optical, magnetic, flash, or otherwise. The controller 50 also includes sufficient amounts of random access memory, electrically-erasable programmable read only memory, and the like, as well as a high-speed clock, analog-to-digital and digital-to-analog circuitry, and input/output circuitry and devices, as well as appropriate signal conditioning and buffer circuitry.
In a possible embodiment, the controller 50 may include multiple control modules each having dedicated functions. For instance, in the embodiment of
The controller 50 may include additional control modules or processors necessary for monitoring the starting process, recording the needed data, and performing the disclosed diagnosis. Such a control module could be a diagnostic tool connected to the CAN bus, or a combination of an onboard module and an off-board back-office server where the onboard module monitors the starting process and collects the needed data and sends the data to the back-office server and the back-office server performs the diagnosis based on the data received. In other words, the methods of the present disclosure are not limited by the ways in which such methods are implemented.
If the CAN bus and associated communications protocols and supporting hardware function properly, the ECM 52 will receive the crank request signal (arrow 33) and, in response, enable the starter control relay 20 via an electronic enabling signal (arrow EN). Thereafter, as is known in the art, the battery 19 powers the starter motor 24, the pinion gear 26 of the starter motor 24 is translated into engagement with the flywheel 28 or a geared element connected thereto, as indicated by double-headed arrow 11, and the engine 12 is rotated to above a threshold speed. Above the threshold speed, a fuel delivery system 30 supplies fuel (arrow F) to the engine 12 via a fuel pump 32 and other components such as a fuel rail and injectors (not shown). Thereafter, the pinion gear 26 disengages from the flywheel 28 and the starter motor 24 turns off.
In a successful start of the engine 12, the engine 12 should smoothly crank and start within a few seconds of receipt by the ECM 52 of the crank request signal (arrow 33). However, when the start event is unsuccessful, a “no-start” condition is presented. The controller 50 is therefore configured to diagnose and handle such faults as set forth herein with reference to
In particular, the controller 50 is programmed to diagnose no-start/starter-enabled faults in a manner that depends on whether the powertrain 10 uses an optional intelligent battery sensor (SI). As is known in the art, an intelligent battery sensor (SI) measures a maximum cranking current (IMAX) from the battery 19, as well as determines a maximum voltage. When no sensor (SI) is used, the controller 50 may execute a method 100, e.g., as shown in
The controller 50 in both of the methods 100 and 100A records a set of starter data over a calibrated sampling duration, doing so in response to a requested start event when the solenoid control relay 20 is in the enabled state. The controller 50 determines or receives a cranking voltage (VC) and a speed (RPME) of the engine 12, e.g., as reported values from the ECM 52 or as directly measured. The controller 50 then derives a resistance value, with the identity of the derived resistance value depending on whether or not the powertrain 10 includes the intelligent battery sensor (SI).
With respect to the resistance value in particular, if the starter system 18 is characterized by an absence of the intelligent battery sensor (SI), the controller 50 derives a resistance ratio (R) as a function of an open-circuit voltage (VOC) and a minimum cranking voltage (VMIN) of the battery 19 as set forth below with reference to
In the example table 40, a set of parameters for associated starter data includes cranking voltage (VC), engine speed (RPME), a battery/starter resistance ratio (R), starter resistance (RS), battery resistance (RB), cranking current (IC), and engine torque (TE). As noted above, some of these values are not used depending on whether or not the starter system 18 includes the intelligent battery sensor (SI). The controller 50 examines the set of starter data collected or reported to the ECM 52 or other control modules, and determines which of the fault classes I-VI is present.
For instance Fault Class I is present when the cranking voltage (VC) is at a constant high level (H), engine speed (NE) is zero, and cranking current (IC) is at a constant low level (L) with zero engine torque (TE). Any of the fault classes may be present, with the different fault classes determined based on the high (H)/normal (N)/low (L)/or variant (V) levels of the associated parameters of
Referring to
Method 100 begins with step S102, wherein the controller 50 receives and records a set of starter data over a calibrated sampling duration in response to a requested start event when the solenoid control relay 20 is in an enabled state, i.e., when the ECM 52 has transmitted the enable signal (arrow EN) to the starter control relay 20. The starter data includes the cranking voltage (VC)/cranking current (IC) and engine speed (NE) shown in
Step S103 includes recording a diagnostic code corresponding to a data collection/transfer fault. The ECM 52 disables the starter system 18, and the method 100 is complete.
Step S104 includes the optional step of removing the earliest- and latest-collected data from step S102, e.g., the first and last second or two of data in an example embodiment. Such a step may help avoid transient noise or other effects during measurement of the starter data. The method 100 then proceeds to step S106.
At step S106, the controller 50 determines whether all measured cranking voltages (VC) over the duration of the collected starter data equal or exceed a voltage threshold, e.g., 11 VDC, and that all engine speeds (RPME) are zero. Step S107 is executed if either condition is not present, and to step S108 when both conditions are satisfied.
At step S107, the controller 50 derives a resistance ratio (R) using an open-circuit voltage (VOC) and a minimum cranking voltage (VMIN) of the battery 19. As is known in the art, open-circuit voltage (VOC) is determined from a mapping table based on battery state of charge and battery temperature. Thus, memory (M) of the controller 50 may be programmed with such a table. As is known in the art, both battery state of charge and battery temperature are measured/estimated and reported to the controller 50 as part of the ongoing operation of the powertrain 10. The minimum cranking voltage (VMIN) is likewise a value known to the controller 50, e.g., via the BCM 54, as an internally stored value. The method 100 then proceeds to step S109.
Step S108 includes executing a control action corresponding to a lack of power to the starter motor 24, a faulty wire conducting the enable signal (EN), a faulty solenoid 22, or a faulty power/ground conductor to the starter motor 24, or an open-circuit fault of coils of the starter motor 24. Upon diagnosis, the further distinguishing between these possible faults may thereafter be achieved in a more efficient manner by a service technician. The method 100 is then finished (*).
Step S109 includes determining whether all engine speeds (RPME) in the collected starter data exceed a speed threshold, e.g., 160 RPM. The method 100 proceeds to step S111 when all engine speeds (RPME) in the collected starter data exceed a speed threshold, and to step S113 when the engine speeds (RPME) do not exceed such a speed threshold.
Step S111 includes executing a control action corresponding to a second identified fault mode, which in this instance corresponds to a faulty engine 12 or fuel delivery system 30. The method 100 is then finished (*).
Step S113 includes determining if the prior-calculated resistance ratio (R) is within a predefined or normal/expected range, with such a range being a calibrated value that could vary based on the powertrain 10. The method 100 proceeds to step S114 if the resistance ratio (R) is not within the normal/expected range, and to step S115 if the resistance ratio (R) is within the normal/expected range.
At step S114, the controller 50 executes a control action corresponding to a third identified fault mode, which in this instance corresponds to low state of charge/high resistance level of the battery 19, or a short in the starter motor 24, or a high resistance level in the starter motor 24. In step S114, the controller 50 may use the value of the resistance ratio (R) to further distinguish which of these fault modes are present, e.g., by assigning different possible ranges of the resistance ratio (R) to the various fault modes. The method is then finished (*).
At step S115, the controller 50 determines if an average cranking current over the duration of step S102 exceeds a calibrated current threshold, or in the alternative, whether a torque level of the starter motor 24 of
Step S116 includes executing a control action corresponding to a fourth identified fault mode, which in this instance corresponds to a faulty pinion gear 26, clutch C1, flywheel 28, or a weak magnetic field of the starter motor 24. Distinguishing between these possible faults may then be achieved in a more efficient manner by a service technician. The method 100 is then finished (*).
Step S117 includes executing a control action corresponding to a fifth identified fault mode, which in this instance corresponds to a seized engine 12 or a high-friction condition in the engine 12. Again, distinguishing between these two possible faults may be achieved by a service technician. The method 100 is then finished (*).
With respect to alternative step S107A, the controller 50 derives a battery resistance ratio (RB) and a starter resistance (RS) using a maximum current (IMAX), an open-circuit voltage (VOC) a minimum cranking voltage (VMIN) of the battery 19. Both the open-circuit voltage (VOC) is and the minimum cranking voltage (VMIN) are described above with reference to
To perform step S107A, the controller 50 may solve the equations:
The method 100A then proceeds to step S109 as described above.
Alternative step S113A includes determining if the battery and starter resistances RB and RS, respectively, are both within a respective predefined or normal/expected range, with such a range being a calibrated value that could vary based on the configuration of the powertrain 10. The method 100A proceeds to step S114A if the resistances RB and RS are not within the normal/expected range, and to step S115 if the resistances RB and RS are within the normal/expected range.
At step S114A of method 100A, the controller 50 executes a control action corresponding to a third identified fault mode, which in this instance corresponds to low state of charge/high resistance level of the battery 19, or a short in the starter motor 26, or a high resistance level in the starter motor 26. In step S114A, the controller 50 may use the value of the respective battery and starter resistances RB and RS to further distinguish which of these particular fault modes are present, e.g., by assigning different possible ranges of the respective battery and starter resistances RB and RS, either alone or together, to the various fault modes. The method 100A is then finished (*).
Using the method 100 or 100A integrated into the powertrain 10 described above, a no-start condition with an enabled starter control relay 20 may be diagnosed in the powertrain 10 without the need for additional sensing hardware. Starter data is recorded over a calibrated sampling duration in response to a requested start event when the solenoid relay is in an enabled state. The resistance ratio (R) is derived (
While the best modes for carrying out the disclosure have been described in detail, those familiar with the art to which this disclosure relates will recognize various alternative designs and embodiments for practicing the disclosure within the scope of the appended claims.
