POWERTRAIN SYSTEM WITH FAULT-TOLERANT Coast Control Logic

Abstract

Powertrain system (10) comprising: an internal combustion engine (14); an auxiliary starter (45) operatively connected to the internal combustion engine (14) and selectively configured to start the internal combustion engine (14); a rechargeable energy storage system (54) electrically connected to the auxiliary starter (45); a frequency analyzer device (S Z ); and a controller (50) programmed to provide fault-tolerant coasting control of the powertrain system (10), the controller (50) being configured to receive an actual impedance value of the rechargeable energy storage system (54) from the frequency analyzer device (S Z ) is programmed at a calibrated frequency while the combustion engine (14) is running; characterized in that the powertrain system (10) further comprises an additional energy storage system (56) electrically parallel to the energy storage system (54); wherein the controller (50) is further programmed to: Comparing the actual impedance value with a calibrated impedance value; and Executing a coasting maneuver of the drive train system (10) by shutting down the internal combustion engine (14) above a speed limit when the actual impedance value is lower than the calibrated impedance value; Commanding a start of the internal combustion engine (14) using energy from the additional energy storage system (56) to thereby exit the coasting maneuver if the actual impedance value exceeds the calibrated impedance value; and Prevent subsequent execution of the coasting maneuver as long as the actual impedance value exceeds the calibrated impedance value.

Description

TECHNICAL FIELD

[0001] The present invention relates to a drive train system according to the preamble of claim 1, as is essentially known from DE 10 2010 061 141 A1.

[0002] Further prior art can also be found in the documents DE 10 2010 032 280 A1, JP 2010 - 121 459 A, US 2015 / 0 198 675 A1 and DE 11 2013 004 514 T5. BACKGROUND

[0003] In a powertrain with an internal combustion engine connected to a transmission, a 12-volt DC auxiliary starter motor can be selectively engaged to rotate an engine crankshaft and thus start the engine. Hybrid powertrains use an engine in conjunction with one or more electric motors to optimize powertrain efficiency. One type of hybrid-electric powertrain uses a belted alternator starter (BAS), in which the electric motor is connected to the crankshaft, such as via a belt and pulley system. The auxiliary starter motor or the electric motor can be used to start the engine in some powertrain configurations, with engine torque used to power the electric motor in generator mode to recharge an electronic storage system. SUMMARY

[0004] According to the invention, a drive train system is presented which is characterized by the features of claim 1.

[0005] Furthermore, a method for providing fault-tolerant coasting control of a powertrain system having an internal combustion engine, an auxiliary starter, a first energy storage system (ESS), and a controller is described. In one embodiment, the method includes receiving a measured actual impedance value of the first energy storage system via the controller through a frequency analyzer device at the calibrated frequency (ω), for example, 1000 Hz ± 500 Hz. This occurs while the engine is running. The method also includes comparing the measured actual impedance value with a calibrated impedance value and enabling the powertrain system to perform a coasting maneuver via the controller, i.e.Turning off the engine above a speed limit, such as vehicle or engine speed, only if the measured actual impedance value is lower than the calibrated threshold impedance value.

[0006] The method may also include starting the engine during the coast-to-stop maneuver using energy from a second energy storage system to thereby exit the coast-to-stop maneuver. This occurs when the measured actual impedance value exceeds the calibrated impedance value. The method also includes preventing subsequent execution of the coast-to-stop maneuver in the controller logic as long as the measured actual impedance value remains relatively high compared to the calibrated impedance value.

[0007] The second energy storage system in this embodiment may be a non-rechargeable or rechargeable device, for example a primary or secondary battery, respectively.

[0008] Starting the engine using energy from the second energy storage system may involve driving a relay or other mechanical or semiconductor switch to connect the second energy storage system to the auxiliary starter. The second energy storage system may be a supercapacitor in some embodiments.

[0009] The detailed description and drawings support and describe the invention, but the scope of the invention is defined solely by the claims. While some of the best modes contemplated for carrying out the claims have been described in detail, several alternative modes for practicing the invention are also possible, as defined in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic diagram of an exemplary powertrain system including a motor and a controller programmed with fault-tolerant coastdown control logic as set forth herein. Fig. 2 is a schematic representation of impedance values ​​of an exemplary energy storage system of the powertrain system as shown in Fig. 1 shown. Fig. 3A-B are schematic representations of possible configurations of alternative embodiments of an electrical system as part of the powertrain system, as in Fig. 1 shown. Fig. 4 is a schematic representation of an exemplary four-pole design of the energy storage systems usable in the powertrain system for independent fault diagnosis, as in Fig. 1 shown. Fig. 5 is a flowchart describing an exemplary method for executing fault-tolerant controls of a coastdown maneuver of the powertrain system, as in Fig. 1 shown. DETAILED DESCRIPTION

[0010] Referring to the figures, wherein like reference numerals indicate like or corresponding parts throughout the several views, a powertrain system 10 is shown in Fig. 1. In various embodiments, the powertrain system 10 may be any system having a powertrain 12 that includes an internal combustion engine (E) 14. The powertrain system 10 may be variously embodied as a vehicle, a power generation or manufacturing facility, a fluid pipeline pumping system, or another system having periods of reduced or no load on the engine 14, where the effect of stopping the engine 14 at certain points in operation would reduce fuel consumption and noise and / or provide other benefits. Possible vehicle embodiments include mobile machines operable to transport people or cargo, for example, conventional wheeled motor vehicles such as cars, trucks, buses, motorcycles, and bicycles, and may further include rail vehicles, watercraft, aircraft, or spacecraft, depending on the configuration.For illustrative simplicity, a motor vehicle will be used hereinafter, and the powertrain system 10 will be described as a vehicle 10, without limiting the application to such an embodiment.

[0011] The vehicle 10 may include, in addition to the above-mentioned drive trains 12 and 14, a transmission (T) 16 and an electric motor 38, the latter being Fig. 1 can also be referred to as MGU for specifying possible motor and generator functionality, depending on the operating mode. The motor 14 and / or the electric motor 38 provide drive torque (arrow T I ) to an input element 24 of the transmission 16. The transmission 16 can be connected to drive wheels 20 of the vehicle 10 and output torque (arrow T O ) via a final drive unit 18 in the non-limiting embodiment of the vehicle 10, as shown in Fig. 1 shown.

[0012] The powertrain 12, as configured herein, includes an electrical system 22 operable to start and stop the engine 14 as needed, such as to conserve fuel. In the vehicle 10, this may occur while idling, while stopped at a stoplight, or at higher vehicle speeds of the vehicle 10 or the engine 14 during coasting. As used herein, the terms "coasting" and "coasting maneuver" refer to an operating mode in which the vehicle 10 is operated with the engine 14 off above a certain speed, for example, 80 km / h ground speed. Although omitted for clarity, the electrical system 22 may include other components, such as power electronics, voltage regulators, inverters, and the like.

[0013] A controller 50 is connected to a frequency analyzer device S Zequipped, for example, a microchip or a circuit that operates to directly measure the impedance via a first energy storage system 54 (ESS1) at a calibrated frequency (ω), as described below with reference to Fig. 2. The controller 50 is further programmed to selectively prevent the initiation of the coasting maneuver if an abrupt / high-frequency fault, such as a short-term or long-term electrical failure of the first energy storage system 54, is detected via the frequency analyzer device Sz. When the coasting maneuver is active, the controller 50 is operable to request an automatic start of the engine 14 via a second energy storage system 56 (ESS2). Possible embodiments of the electrical system 22 are described below with reference to Fig. 3A-B. An embodiment of a four-terminal package of the first and second energy storage systems 54 and 56 is shown in Fig. 4. An exemplary method 100 for implementing fault-tolerant logic while driving around is described with reference to Fig. 5 described.

[0014] The control 50 from Fig. 1 may be configured as a computer with common elements such as the processor (P) and a memory (M). The memory is a tangible, non-temporary storage device or medium, such as read-only memory, RAM, optical storage, flash memory, electronically programmable read-only memory, etc. The controller 50 may also include any necessary logic circuitry, including, but not limited to, proportional-integral-derivative (PID) control logic, a high-speed clock, analog-to-digital (A / D) circuitry, digital-to-analog (D / A) circuitry, digital signal processors or DSPs, and the necessary input / output (I / O) units, as well as other signal conditioning and / or buffer circuitry.

[0015] Regarding the exemplary vehicle 10 from Fig. 1, a crankshaft 23, which carries torque from the engine 14, is selectively connected to the input member 24 of the transmission 16. The transmission 16 may include a gear arrangement and one or more clutches through which torque is transferred from the engine 14 to the input member 24, then to the final drive 18 and the drive wheels 20. The drive wheels 20 may be front wheels and / or rear wheels of the vehicle 10 in alternative designs.

[0016] The vehicle 10 may be equipped with a Belted Alternator Starter System (BAS), as shown. In such an embodiment, an endlessly rotatable drive member 37, such as a closed-loop belt or chain, is driven via a first pulley 34 or a second pulley 48, depending on the operating mode. The first pulley 34 is connected to the crankshaft 23 so that the first pulley 34 and the crankshaft 23 can rotate together. The electric motor 38 is also selectively connected to the engine 14, with torque from the electric motor 38 driven by the electrical system 22 via an inverter module (PIM) 49 if the electric motor 38 is a multi-phase device, and is optionally used to assist the torque of the engine 14 or to charge an energy storage system (ESS1) 54 to reduce fuel consumption and emissions of the vehicle 10.For example, in certain embodiments, the electric motor 38 may start the engine 14 from the belt side of the engine 14 via a second pulley 48 or provide torque to the crankshaft 23 to assist in propelling the vehicle 10, such as during coasting or clutching with the engine 14 off. The electric motor 38 may also be selectively used as a generator to generate electrical power or recharge the first energy storage system 54, and in some embodiments, the second energy storage system 56.

[0017] An auxiliary starter 45 (M S) can be selectively activated to deliver torque to the crankshaft 23. For example, the starter 45 may again draw power from the electrical system 22 via the PIM 49 if the starter 45 is a multi-phase device or a direct DC motor device. Once power is flowing, the starter 45 may deliver motor torque via a gear member 63 to a ring gear 30 connected to the crankshaft 23, which, as set forth below, draws power from the electrical system 22. The starter 45 may be connected to the electric motor 38 in some embodiments, for example, via the gear member 60, as schematically shown in Fig. 1. Other embodiments may omit the use of the separate starter 45 and utilize a 12-volt DC electric motor 38 for engine starting and torque assist without departing from the scope of the invention.

[0018] The electric motor 38 includes a rotor shaft 44 that selectively transmits engine torque to the crankshaft 23 for starting the engine 14. The second pulley 48 is connected to the rotor shaft 44. For certain operations, the rotor shaft 44 and the second pulley 48 can rotate together, while in other operations, the rotor shaft 44 and the second pulley 48 can rotate separately, or only one of them rotates.

[0019] With reference to the electrical system 22 of Fig. 1, the controller 50 is specifically programmed to detect high-frequency failure modes, where "high-frequency" is used herein to refer to electrical frequency as opposed to temporal frequency. Exemplary high-frequency failure modes include an electrical short circuit or a sudden loss of conductivity, each of which may prevent starting of the motor 14 during a coast-to-stop maneuver. The controller 50 is also programmed to perform a control action with respect to the powertrain 12 via powertrain control signals (arrow 11) based on this evaluation, such as preventing the vehicle 10 from coasting by setting a diagnostic code, alarm, etc. As is known in the art, the state of the motor 14 may oscillate along a path during coasting, i.e., be turned on and off depending on the optimal hybrid propulsion mode.When the engine 14 is shut down, the first energy storage system 54 can fire the electric motor 38. Thus, the engine 14 cannot be restarted if an electrical short circuit occurs in the first energy storage system 54 and, consequently, any motor-driven power system connected in . Fig. 1 as auxiliary load (L) 58, may not be activated. Therefore, the controller 50 is programmed with computer-readable instructions according to the method 100 for preventing this event via early detection of high-frequency electrical failures and for preventing initiation of a coastdown maneuver when such a failure mode is present or occurs during a particular coastdown maneuver.

[0020] To achieve the desired results, the controller 50 may control the frequency analyzer device S Zinclude or be connected to a sensor operable to measure a total impedance Z(w) across the first energy storage system 54 at a calibrated frequency (ω) when the engine 14 is running. The second energy storage system 56 may be evaluated in a similar manner. In a particular non-limiting embodiment, the calibrated frequency (ω) is about 1000 Hz. That is, a normal duration (T) of a pulse peak power when cranking and starting the engine 14 lasts about 1 millisecond, corresponding to a frequency (ω) equal to 1T or 1000 Hz. Sufficient performance may be advantageous within reasonable levels of this frequency, for example, 1000 Hz ± 500 Hz. Embodiments of more than 1500 Hz or less than 500 Hz may be used within the scope of the invention, for example, at 1 Hz-1 MHz. However, at least with respect to higher frequencies, inductive effects may result that are difficult to characterize.

[0021] In the embodiment of the Fig. 1, the second energy storage system 56 can be used as a primary battery, i.e., a replaceable battery that cannot be recharged. Such a device has a low mass relative to the first energy storage system 54 and can be dimensioned for a limited number of starts, for example, 5-10 starts, before replacement is necessary. A series of 3 VDC, 1200 mAh polycarbonate monofluoride lithium batteries can be used in one possible configuration, or any other suitable rugged, expendable high / low temperature design. Such a small battery is intended for emergency starting of the engine 14 to provide the operator of the vehicle 10 with Fig. 1 to enable easy exit from the coasting maneuver when the impedance of the first energy storage system 54 is above a calibrated impedance value. Therefore, when the controller 50 detects impedance above a calibrated impedance value at, for example, 1000 Hz ± 500 Hz, as mentioned above, the controller 50 can command the closure of a switch S1 for connecting the second energy storage system 56 to the electric motor 38.

[0022] Briefly referring to Fig. 2, an exemplary impedance curve Z(w) has imaginary and real terms, as known in the art, with imaginary impedance (Z IM ) on the vertical axis and real impedance (Z R ) on the horizontal axis, as shown. Z(ω)=[(ZIM)2+(ZR)2]

[0023] A calibrated new energy storage system 54 may have the total impedance curve Z(w) with a high-frequency intersection point 62 indicating a purely resistive drop. If a particular energy storage system experiences a high-frequency failure, such as an electrical short circuit or loss of conductivity, for example, due to age, the impedance curve shifts to Fig. 2 to the right to create a new impedance curve Z(ω) N and define a new intersection point 162.

[0024] The controller 50 may measure the total impedance of the energy storage system 54 or 56 at the calibrated frequency (ω) using the frequency analyzer device S Zquery, compare the measured impedance with a calibrated impedance value, and execute a control action with respect to the drive train 12 if the measured impedance exceeds the calibrated impedance value. This means that the controller 50 can ensure that the motor 14 is not turned off when the measured impedance exceeds the calibrated impedance value, in addition to performing other control actions that trigger services. In a particular embodiment, the frequency analyzer device S Z be an integrated circuit or chip used to directly measure impedance with a high degree of accuracy. Since electrical currents in electrical systems 22 are generally low, calculating impedance from voltage and current does not provide optimal accuracy, and thus the frequency analyzer device S Z a precise hardware solution as part of the electrical system 22.

[0025] Referring to Fig. 3A and Fig. 3B, which shows two possible electrical systems 122 and 222, may be an embodiment of a primary battery of the second energy storage system 56 of the Fig. 1 may alternatively be used as a second energy storage system 156 with a secondary / rechargeable configuration. The first and second energy storage systems 54 and 156 may be similar or identical modules arranged electrically in parallel, for example, as two identical lead-acid battery modules. The first switch (S1) may be commanded by control signals (arrow 11) from the controller 50 to selectively disconnect the first and second energy storage systems 54 and 156 from the powertrain 12 as needed based on the impedance evaluation performed by the controller 50 at the calibrated frequency (ω), as in the example of the 12 VDC electrical system 122 of Fig. 3A.

[0026] In Fig. 3B, the second energy storage system 156 in the electrical system 222 may be a supercapacitor sized to restart the engine 14 or to accept a charge from the engine 14 as needed. In a normal mode, switch S2 is opened and switch S1 is closed, thereby connecting the first energy storage system 54 to the electric motor 38. In a coast-to-stop mode of operation, switch S1 may be opened, thereby disconnecting the first energy storage system 54 and connecting the second energy storage system 156. At the same time, the controller 50 may record a diagnostic code that may prompt an operator of the vehicle 10 from Fig. 1 with the service of the first energy storage system 54 and also prevents the drive train 12 from performing a coasting maneuver until the first energy storage system 54 is repaired or replaced.

[0027] Referring to Fig. 4, as mentioned in the embodiments above, the respective first and second energy storage systems 54 and 56 may be packaged together such that the first energy storage system 54 is located immediately adjacent to the second energy storage system 56 to form a single battery module 59. However, each of the first and second energy storage systems 54 and 56 receives its own positive and negative terminals T 54 and T 56upright, so that the battery module 59 is a four-terminal design. The use of four terminals instead of two enables independent evaluation and diagnosis of the first and second energy storage systems 54 and 56. In this way, complete failure tolerance is provided for both the first and second energy storage systems 54 and 56. The four-terminal configuration also protects the second energy storage system 56 from disconnection in the event that the first energy storage system 54 becomes disconnected, which would not be possible in a two-terminal design.

[0028] Fig. 5 shows an exemplary method 100 for providing fault-tolerant coasting control of the powertrain 12 of the Fig. 1 in any of its disclosed embodiments. Beginning with step S102, the controller 50 receives the impedance measurements from the frequency analyzer device S Z out of Fig. 1 at the calibrated frequency (ω) while the engine 14 is running and providing the required drive torque to the transmission 16. The method 100 proceeds to step S104, but continues to periodically receive the impedance measurements according to predetermined sample control loops.

[0029] Step S104 involves comparing the measured impedance value from step S102 with a calibrated impedance value. The method 100 proceeds to step S106 if a value less than the calibrated impedance value is detected, or to step S108, alternatively, if a value exceeding the calibrated impedance value is detected, or, as mentioned below, an impedance trajectory indicates that the measured impedance is likely to exceed the calibrated impedance value during the coast-out maneuver.

[0030] In step S106, the controller 50 enables the coasting / clutching maneuver. Step S106 may require setting a flag bit or authorization in memory (M) so that a separate controller or the controller 50 can subsequently enable the engine 14 to shut down and coast to start. The method 100 then proceeds to step S110.

[0031] In step S108, the controller 50 deactivates the coasting maneuver. Step S108 may require a flag bit or permission in memory (M) so that a separate controller or the controller 50 can prevent the engine 14 from shutting down and coasting. Step S108 may also include setting a diagnostic code in memory (M) and, if appropriate, activating a signal lamp within the vehicle 10, sending a text message, or otherwise alerting an operator of the vehicle 10 to service the first energy storage system 54 or the second energy storage system 56 or 156, depending on which device is being evaluated.

[0032] Step S110 involves determining, during coasting, whether the received impedance value remains less than the aforementioned calibrated impedance value. This means that the first energy storage system 54 may be experiencing a fault while the powertrain 12 is actively coasting, or the controller 50 may determine that such a fault is likely to occur after entering the coasting maneuver, as discussed below. In this case, the method 100 proceeds to step S112.

[0033] In step S112, the controller 50 may execute a control action with respect to the powertrain 12. In this case, the controller 50 may switch the first switch S1 of the Fig. 3A to connect the second energy storage system 56 to the starter 45, thereby starting the engine 14 and initiating the coasting maneuver, after which the process proceeds to step S108. Or the controller 50 can activate the first and second switches S1 and S2 of the Fig. 3B for connecting the supercapacitor embodiment of the second energy storage system 156 to the starter 45 of the Fig. 1, thereby starting the motor 14. Once started, the supercapacitor can be recharged, for example, using a generator or other electrical power generating device (not shown) driven by the motor 14.

[0034] Those skilled in the art will recognize that other variations of the method 100 may be provided. For example, a predictive or preemptive embodiment may be provided in which the engine 14 of the Fig. 1 is not permitted to switch off and initiate the coasting maneuver if the controller 50 determines that an impedance change trajectory results in the measured impedance of the first energy storage system 54 exceeding the calibrated impedance value during the coasting maneuver.

[0035] That is, instead of evaluating the impedance of the first energy storage system 54 from the time the coasting maneuver is to be commanded or activated by the controller 50, the controller 50 may calculate an impedance trajectory using the measured actual impedance value and then activate the coasting maneuver only if the measured actual impedance value is lower than the calibrated impedance value and the impedance trajectory does not cause the measured impedance value to exceed the calibrated impedance value during the duration of the coasting maneuver.

[0036] For example, the controller 50 can evaluate the impedance change at several different times over a calibrated interval before entering the coast-out maneuver. By projecting the impedance change over a likely duration of the coast-out maneuver, the controller 50 can quickly determine whether the impedance of the first energy storage system 54 exceeds the calibrated impedance value during the course of the coast-out maneuver. In such a case, the controller 50 can preemptively prevent entry into the coast-out maneuver and execute the necessary control actions mentioned above, such as setting a diagnostic code or otherwise alerting an operator of the current status of the energy storage system 54.

Claims

[1] Powertrain system (10) comprising: an internal combustion engine (14); an auxiliary starter (45) operatively connected to the internal combustion engine (14) and selectively configured to start the internal combustion engine (14); a rechargeable energy storage system (54) electrically connected to the auxiliary starter (45); a frequency analyzer device (S Z ); and a controller (50) programmed to provide fault-tolerant coasting control of the powertrain system (10), the controller (50) being configured to receive an actual impedance value of the rechargeable energy storage system (54) from the frequency analyzer device (S Z ) is programmed at a calibrated frequency while the combustion engine (14) is running; characterized by , that the powertrain system (10) further comprises an additional energy storage system (56) electrically parallel to the energy storage system (54); wherein the controller (50) is further programmed to: Comparing the actual impedance value with a calibrated impedance value; and Executing a coasting maneuver of the drive train system (10) by shutting down the internal combustion engine (14) above a speed limit when the actual impedance value is lower than the calibrated impedance value; Commanding a start of the internal combustion engine (14) using energy from the additional energy storage system (56) to thereby exit the coasting maneuver if the actual impedance value exceeds the calibrated impedance value; and Prevent subsequent execution of the coasting maneuver as long as the actual impedance value exceeds the calibrated impedance value. [2] The powertrain system (10) of claim 1, wherein the additional energy storage system (56) is a non-rechargeable device. [3] The powertrain system (10) of claim 1, wherein the additional energy storage system (56) is a rechargeable device. [4] The powertrain system (10) of claim 1, wherein the controller (50) is programmed to start the internal combustion engine (14) by activating a switch (S1) thereby connecting the additional energy storage system (56) to the auxiliary starter (45). [5] The powertrain system (10) of claim 1, wherein the controller is programmed (50) to calculate an impedance trajectory using the actual impedance value and to enable performance of the coasting maneuver only if the actual impedance value is lower than the calibrated impedance value and the calculated impedance trajectory does not result in the actual impedance value exceeding the calibrated impedance value during the coasting maneuver. [6] The powertrain system (10) of claim 1, wherein the calibrated frequency is 1000 Hz ± 500 Hz. [7] The powertrain system (10) of claim 1, wherein the additional energy storage system (56) and the rechargeable energy storage system (54) have separate positive and negative terminals with respect to each other. [8] The powertrain system (10) of claim 1, wherein the speed limit is an internal combustion engine speed. [9] The powertrain system (10) of claim 1, wherein the speed limit is a vehicle speed.

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