Method for controlling a stop / start vehicle

Abstract

The present application relates to a method for controlling a stop / start vehicle, presenting a method for enabling or disabling automatic engine stopping and starting. In one example, an engine cranking time is predicted and compared to a threshold value to determine whether to enable or disabling automatic engine stopping and starting. The predicted engine cranking time is a metric used to determine whether a vehicle occupant is likely to find a possible subsequent vehicle operation delay due to an engine starting event objectionable.

Description

Technical Field

[0001] The present description relates to methods and systems for operating a vehicle powertrain system including an internal combustion engine that can be automatically stopped and started. The methods and systems may be particularly useful for inhibiting automatic engine stops during conditions where engine cranking may continue for more than a threshold amount of time. Background Art

[0002] During a condition where the driver requests less than a threshold torque amount, the internal combustion engine of the vehicle can be automatically stopped. The engine can be automatically stopped when the vehicle is decelerated or after the vehicle is completely stopped. During the automatic engine stop, the delivery of fuel to the engine can be terminated and the engine rotation can be stopped. By terminating combustion and stopping the engine, fuel may be saved and the vehicle's mileage may be extended. It may be desirable to stop the engine frequently to increase vehicle fuel economy. However, if the battery of the vehicle is in a low state of charge, the engine may not be restarted due to insufficient engine start torque. In addition, if the engine is stopped, it may take more than a threshold amount of time to restart the engine. When there is partial degradation in the engine start rotation system, the engine start time may increase. For example, when the battery state of charge is low, the internal resistance of the battery is high, the starter is aged, or when the engine lubrication is different from expected, the engine start rotation time may increase. When the components of the engine start rotation system are not degraded, the engine start rotation time may be within the expected threshold duration. The driver or passenger of the vehicle may notice that the engine start rotation time is extended and find it offensive. Summary of the invention

[0003] The inventors herein have recognized the above problems and developed a vehicle operating method that includes: automatically stopping and starting an engine; and inhibiting automatically stopping the engine in response to an estimated engine cranking time exceeding a threshold.

[0004] By prohibiting or disallowing automatic engine stops in response to an estimated engine cranking time, excessive engine cranking times can be prevented while still allowing automatic engine stops when the engine cranking time is expected to be short. Thus, at least a portion of the vehicle fuel economy gains achieved by automatic engine stops can be maintained without the vehicle occupants having to endure long engine cranking times. In addition, estimates of engine cranking duration can be revised to reflect data captured during the most recent automatic engine start condition so that engine cranking estimates can be more accurate.

[0005] The present description may provide several advantages. For example, the method may reduce the likelihood that a vehicle occupant will object to a long engine cranking time. Furthermore, the method may save fuel by allowing automatic engine stops and starts when the engine cranking time is expected or estimated to be less than a threshold amount of time. Furthermore, the method may dynamically change how the engine cranking time is estimated to accommodate different vehicle platforms and maintain system functionality during some conditions of system degradation.

[0006] The above advantages and other advantages and features of the present specification are apparent in the following detailed description when taken alone or in conjunction with the accompanying drawings.

[0007] It should be understood that the above is provided to introduce in a simplified form a selection of concepts that will be further described in the detailed description. This is not meant to identify key or essential features of the claimed subject matter, the scope of which is uniquely defined by the appended claims. Furthermore, the claimed subject matter is not limited to embodiments that address any disadvantages noted above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 A schematic diagram showing an internal combustion engine that can be automatically stopped and started;

[0009] Figure 2 Shown for Figure 1 A schematic diagram of electrical components of an engine starting system for an internal combustion engine is shown;

[0010] Figure 3 Exemplary engine cranking currents for three different batteries are shown;

[0011] Figure 4 Exemplary engine cranking times for different amounts of engine cranking energy are shown;

[0012] Figure 5 shows exemplary engine cranking times for different engine cranking currents;

[0013] Figure 6 Shows a basis Figure 7 An exemplary vehicle operating sequence of the method of;

[0014] Figure 7 An exemplary method for operating a vehicle is shown; and

[0015] Figure 8 An exemplary method for inhibiting automatic engine starts and stops is shown. DETAILED DESCRIPTION

[0016] This specification relates to authorizing and disabling vehicle entry into an automatic engine start and stop mode that stops the engine without a vehicle occupant requesting an engine stop through a dedicated input device (e.g., a key switch or button) having the sole function of starting and stopping the engine. Figure 1 An engine that can be stopped and started automatically is shown. Figure 2 The electrical system shown is used to automatically start the engine. Figure 3-5 Exemplary engine cranking conditions during various operating conditions are shown. Figure 6 It is shown in Figure 7 and Figure 8 An exemplary vehicle operating sequence for the method of FIG. Figure 7 A method for authorizing or inhibiting entry into an automatic engine start and stop mode is shown in FIG. Figure 8 A method for inhibiting automatic engine starts and stops is shown in FIG.

[0017] refer to Figure 1 , including multiple cylinders ( Figure 1 Internal combustion engine 10 (one cylinder of which is shown in FIG. 1 ) is controlled by electronic engine controller 12. Engine 10 includes cylinder head 35 and cylinder block 33, which include combustion chamber 30 and cylinder wall 32. Piston 36 is positioned therein and reciprocates through connection with crankshaft 40. Flywheel 97 and ring gear 99 are coupled to crankshaft 40. Starter 96 (e.g., a low-voltage (operating at less than 30 volts) motor) includes pinion shaft 98 and pinion 95. Pinion shaft 98 can selectively advance pinion 95 to engage ring gear 99. Starter 96 can be mounted directly to the front of the engine or the rear of the engine. In some examples, starter 96 can selectively supply torque to crankshaft 40 via a belt or chain. In one example, starter 96 is in a basic state when not engaged to the engine crankshaft. Combustion chamber 30 is shown communicating with intake manifold 44 and exhaust manifold 48 via respective intake valve 52 and exhaust valve 54. Each intake and exhaust valve may be operated by an intake cam 51 and an exhaust cam 53. The position of intake cam 51 may be determined by intake cam sensor 55. The position of exhaust cam 53 may be determined by exhaust cam sensor 57. Intake valve 52 may be selectively activated and deactivated by valve activation device 59. Exhaust valve 54 may be selectively activated and deactivated by valve activation device 58. Valve activation device 58 and valve activation device 59 may be electromechanical devices.

[0018] Fuel injector 66 is shown positioned to inject fuel directly into cylinder 30, which is known to those skilled in the art as direct injection. Fuel injector 66 delivers liquid fuel in proportion to the pulse width from controller 12. Fuel is delivered to fuel injector 66 by a fuel system (not shown) including a fuel tank, a fuel pump, and a fuel rail (not shown). In one example, a high pressure two-stage fuel system may be used to generate higher fuel pressures.

[0019] In addition, intake manifold 44 is shown as being in communication with turbocharger compressor 162 and engine air intake 42. In other examples, compressor 162 may be a supercharger compressor. Shaft 161 mechanically couples turbocharger turbine 164 to turbocharger compressor 162. Optional electronic throttle 62 adjusts the position of throttle plate 64 to control air flow from compressor 162 to intake manifold 44. Since the inlet of throttle 62 is located in boost chamber 45, the pressure in boost chamber 45 may be referred to as throttle inlet pressure. The throttle outlet is located in intake manifold 44. In some examples, throttle 62 and throttle plate 64 may be positioned between intake valve 52 and intake manifold 44, so that throttle 62 is an intake port throttle. Compressor recirculation valve 47 may be selectively adjusted to a plurality of positions between fully open and fully closed. Wastegate 163 may be adjusted by controller 12 to allow exhaust to selectively bypass turbine 164 to control the speed of compressor 162. Air filter 43 cleans the air entering engine air intake 42.

[0020] Distributorless ignition system 88 provides an ignition spark to combustion chamber 30 via spark plug 92 in response to controller 12. Universal or Wide-area Exhaust Gas Oxygen (UEGO) sensor 126 is shown coupled to exhaust manifold 48 upstream of catalytic converter 70. Alternatively, a two-state exhaust gas oxygen sensor may be substituted for UEGO sensor 126.

[0021] In one example, converter 70 may include multiple catalyst bricks. In another example, multiple emission control devices, each having multiple catalyst bricks, may be used. In one example, converter 70 may be a three-way type catalyst.

[0022] The controller 12 Figure 11 is shown as a conventional microcomputer, which includes: a microprocessor unit 102, input / output ports 104, read-only memory 106 (e.g., non-volatile memory), random access memory 108, non-fail-safe memory 110, and a conventional data bus. Controller 12 is shown as receiving various signals from sensors coupled to engine 10, including, in addition to those previously discussed, engine coolant temperature (ECT) from temperature sensor 112 coupled to cooling sleeve 114; position sensor 134 coupled to accelerator pedal 130 for sensing force applied by foot 132; position sensor 154 coupled to brake pedal 150 for sensing force applied by foot 152; measurement of engine manifold pressure (MAP) from pressure sensor 122 coupled to intake manifold 44; engine position sensor from Hall effect sensor 118 for sensing crankshaft 40 position; measurement of air mass entering the engine from sensor 120; and measurement of throttle position from sensor 68. Barometric pressure may also be sensed (sensor not shown) for processing by controller 12. In a preferred aspect of the present description, engine position sensor 118 produces a predetermined number of equally spaced pulses every revolution of the crankshaft from which engine speed (RPM) can be determined.

[0023] During operation, each cylinder within engine 10 typically undergoes a four stroke cycle: the cycle includes an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke. During the intake stroke, exhaust valve 54 is typically closed and intake valve 52 is opened. Air is introduced into combustion chamber 30 via intake manifold 44, and piston 36 moves to the bottom of the cylinder so as to increase the volume within combustion chamber 30. The position of piston 36 near the bottom of the cylinder and at the end of its stroke (e.g., when combustion chamber 30 is at its largest volume) is typically referred to by those of skill in the art as bottom dead center (BDC).

[0024] During the compression stroke, intake valve 52 and exhaust valve 54 are closed. Piston 36 moves toward the cylinder head so as to compress the air within combustion chamber 30. The point at which piston 36 is at the end of its stroke and closest to the cylinder head (e.g. when combustion chamber 30 is at its smallest volume) is typically referred to by those of skill in the art as top dead center (TDC). In a process hereinafter referred to as injection, fuel is introduced into the combustion chamber. In a process hereinafter referred to as ignition, the injected fuel is ignited by known ignition means, such as spark plug 92, resulting in combustion.

[0025] During the expansion stroke, the expanding gases push piston 36 back to BDC. Crankshaft 40 converts piston movement into rotational torque of the rotating shaft. Finally, during the exhaust stroke, exhaust valve 54 opens to release the combusted air-fuel mixture to exhaust manifold 48, and the piston returns to TDC. It should be noted that the above is shown as just one example, and the intake and exhaust valve opening and / or closing timings may vary, such as to provide positive or negative valve overlap, late intake valve closing, or various other examples.

[0026] Figure 2 2 is a schematic diagram showing the electrical components of the engine starting system 200. The engine starting system can automatically start Figure 1 The internal combustion engine is shown.

[0027] The engine 10 may be automatically started in response to the output of the controller 12. Specifically, the controller 12 may start the engine 10 by commanding the starter 96 to engage with the flywheel 97 and rotate the crankshaft of the engine 10. The electric energy storage device (e.g., a battery) 275 supplies power to the engine starter 96, and the electric energy storage device management system 252 senses the voltage, current, resistance, and temperature of the electric energy storage device 275 and the starter 96 through the sensor 222. For example, the sensor 222 may be used to determine the resistance, voltage, temperature, and current of the starter motor winding 299 in the engine starting system 200. After the engine 10 reaches a predetermined speed, the controller 12 may supply fuel and spark to the engine 10. After the engine 10 reaches a predetermined speed or after the engine 10 has been cranked for a predetermined amount of time, the controller 12 disengages the starter 96 from the flywheel 97 and the engine 10.

[0028] therefore, Figure 1 and Figure 2 A system provides a vehicle system comprising: an engine including a starter motor; a battery that selectively supplies charge to the starter motor; and a controller including executable instructions stored in a non-volatile memory, the instructions being used to: predict an engine start rotation time while the engine is rotating, and prohibit automatic stopping of the engine in response to the predicted engine start rotation time exceeding a threshold; and automatically start the engine in response to the predicted engine start rotation time exceeding a threshold when the engine is stopped due to an automatic engine stop.

[0029] The vehicle system also includes instructions for predicting an engine cranking time based on a maximum engine cranking current. The vehicle system also includes instructions for predicting an engine cranking time based on an energy used to crank the engine. The vehicle system includes: wherein the engine cranking time is the time from when the engine rotates from zero speed to the first combustion event since the last engine stop. The vehicle system includes: wherein the engine cranking time is based on the resistance of the starter motor winding.

[0030] Reference now Figure 3 , shows exemplary engine cranking currents for a vehicle. The exemplary engine cranking currents are for a one year old battery (trace 302), an aged battery (trace 304), and a severely aged battery (306) to provide electrical energy to crank the same vehicle under the same conditions (except that different batteries are used to supply electrical energy to crank the engine).

[0031] Figure 3 The graph shown is a graph of battery cranking current (e.g., the current provided by the battery to crank the engine at an engine cranking speed (250 RPM)) versus engine cranking time. The vertical axis represents the battery cranking current, and the battery cranking current increases in the direction of the vertical axis arrow. The horizontal axis represents the engine cranking time (e.g., the amount of time for the engine to rotate from zero engine speed by the starter to the first combustion event after the engine has accelerated from the most recent zero speed condition), and the engine cranking time increases from the left side of the graph to the right side of the graph. For all three examples, the engine cranking begins at time t0.

[0032] It can be observed that the new battery (e.g., solid trace 302) provides the largest peak value of the engine cranking current, which is about 875 amperes in this example. The slightly aged battery (e.g., dashed trace 304) provides the second largest peak value of the engine cranking current, which is about 780 amperes in this example. The severely aged battery (e.g., double-dotted trace 306) provides the smallest peak value of the engine cranking current, which is about 510 amperes in this example.

[0033] As indicated at the vertical marker at time t1, the new battery also exhibited the shortest engine cranking time of about 520 milliseconds. As indicated at the vertical marker at time t2, the slightly aged battery exhibited the next shortest engine cranking time of about 630 milliseconds. As indicated at the vertical marker at time t3, the severely aged battery exhibited the longest engine cranking time of about 880 milliseconds.

[0034] Thus, newer batteries may provide a higher amount of current to crank the engine, and the higher amount of current may reduce the engine cranking time. Older batteries provide a lower amount of current to crank the engine, and the lower amount of current may extend the engine cranking time. The longer engine cranking time and lower engine cranking current may be at least partially due to the increased internal resistance of the aging battery. In this way, the engine cranking current may be correlated to the engine cranking time, and the engine cranking time may be the basis for determining vehicle occupant satisfaction and whether to prohibit automatic engine stopping and starting.

[0035] Reference now Figure 4 , a graph shows exemplary engine cranking times for different amounts of engine cranking energy. The vertical axis of the graph represents the engine cranking time (e.g., the amount of time from the engine speed increasing from zero to the desired non-zero desired cranking speed until the first combustion event (e.g., ignition in a cylinder) since the most recent time when the engine speed was zero), and the engine cranking time increases in the direction of the vertical axis arrow. The horizontal axis represents the engine cranking energy (e.g., the amount of electrical energy used to crank the engine from the most recent engine stop until the engine starts), and the engine cranking energy increases from the left side of the graph to the right side of the graph.

[0036] The graph shows data from three different engine starts. Marker 402 represents the engine start crank time and engine start crank energy for a severely aged battery. Marker 404 represents the engine start crank time and engine start crank energy for a slightly aged battery. Marker 406 represents the engine start crank time and engine start crank energy for a nearly new battery. The data for all three batteries is based on starting the same engine under the same conditions (except that the battery used for each data point is different). Line 450 and line 452 link data points 402, 404, and 406. The equations of these lines can be determined by known methods (e.g., straight line equations and point / slope formulas).

[0037] It can be observed that the newer battery (e.g., data point 406) provides the shortest engine cranking time and provides the greatest amount of engine cranking energy even though the engine cranking time is the shortest. The greater amount of engine cranking energy may be due to the higher engine cranking current provided by the newer battery. Slightly or mildly aged batteries (e.g., data point 404) provide longer engine cranking times and provide a greater amount of engine cranking energy than severely aged batteries. Severely aged batteries (e.g., data point 402) provide the longest engine cranking times and the least amount of engine cranking energy. In this way, engine cranking energy can be correlated to engine cranking time, and engine cranking time can be the basis for determining vehicle occupant satisfaction and whether to prohibit automatic engine stopping and starting. Therefore, Figure 4 is a graph of a function that can be a basis for relating engine cranking energy to engine cranking time.

[0038] Reference now Figure 5 , a graph illustrates exemplary engine cranking times for different amounts of engine cranking current. The vertical axis of the graph represents the engine cranking time, and the engine cranking time increases in the direction of the vertical axis arrow. The horizontal axis represents the peak engine cranking current (e.g., the maximum or upper threshold current amount greater than other currents that crank the engine during engine cranking from the last engine stop until the first combustion event since the last time the engine speed was zero), and the engine cranking current increases from the left side of the graph to the right side of the graph.

[0039] The graph shows data from three different engine starts. Marker 502 represents the engine start crank time and engine start crank current for a severely aged battery. Marker 504 represents the engine start crank time and engine start crank current for a slightly aged battery. Marker 506 represents the engine start crank time and engine start crank current for a nearly new battery. The data for all three batteries is based on starting the same engine under the same conditions (except that the battery used for each data point is different). Line 550 and line 552 link data points 502, 504, and 506. The equations of these lines can be determined by known methods (e.g., straight line equations and point / slope formulas).

[0040] It can be observed that the newer battery (e.g., data point 506) provides the shortest engine cranking time and the greatest amount of engine cranking current. The slightly or mildly aged battery (e.g., data point 504) provides a longer engine cranking time and provides a greater amount of engine cranking current than the severely aged battery. The severely aged battery (e.g., data point 502) provides the longest engine cranking time and the least amount of engine cranking current. In this way, the engine cranking current can be correlated to the engine cranking time, and the engine cranking time can be the basis for determining vehicle occupant satisfaction and whether to inhibit automatic engine stopping and starting. Therefore, Figure 5 is a graph of a function that can be a basis for relating maximum engine cranking current to engine cranking time.

[0041] Reference now Figure 6 , showing that according to Figure 7 An exemplary order of execution of the method. Figure 6 The order can be determined by Figure 1 and Figure 2 system provided. Figure 6 The various graphs of are arranged in time and occur simultaneously. The vertical lines at times t0-t6 represent times of particular interest in the sequence. Figure 6 The predicted sequence shown shows conditions that prevent or inhibit automatic engine stops and starts. The SS markings along each horizontal axis represent a time brake, and the duration of the brake can be short or long.

[0042] from Figure 6 The first graph from the top is a graph of estimated engine cranking time versus time. The vertical axis represents estimated engine cranking time, and the estimated engine cranking time increases in the direction of the vertical axis arrow. The horizontal axis represents time. Time starts on the left side of the graph and increases to the right side of the graph.

[0043] from Figure 6 The second graph from the top is a graph of battery state of charge (SOC) versus time. The vertical axis represents the battery state of charge, and the battery state of charge increases in the direction of the vertical axis arrow. The horizontal axis represents time. Time starts on the left side of the graph and increases to the right side of the graph.

[0044] from Figure 6The third graph from the top is a graph of predicted peak or maximum engine cranking current versus time during the next engine cranking phase after the next engine stop. The vertical axis represents the engine cranking current, and the engine cranking current increases in the direction of the vertical axis arrow. The horizontal axis represents time. Time starts on the left side of the graph and increases to the right side of the graph.

[0045] from Figure 6 The fourth graph from the top is a graph of predicted engine start rotational energy versus time during the next engine start rotation phase after the next engine stop. The vertical axis represents engine start rotational energy, and the engine start rotational energy increases in the direction of the vertical axis arrow. The horizontal axis represents time. Time starts on the left side of the graph and increases to the right side of the graph.

[0046] from Figure 6 The fifth graph from the top is a graph indicating the activated engine cranking time estimation algorithm versus time. The vertical axis represents the engine cranking algorithm, and when the trace is at a lower level near the horizontal axis, algorithm A is active. When the trace is at a higher level near the vertical axis arrow, algorithm B is active. Figure 7 The A algorithm and the B algorithm are described in the method of FIG. The horizontal axis represents time. Time starts on the left side of the graph and increases to the right side of the graph.

[0047] from Figure 6 The sixth graph from the top is a graph indicating whether automatic engine stops and starts are prohibited based on the battery state of charge. When the trace is at a lower level near the horizontal axis, automatic engine stops and starts are not permitted based on the battery SOC. When the trace is at a higher level near the vertical axis arrow, automatic engine stops and starts may be permitted based on the battery SOC. The horizontal axis represents time. Time starts on the left side of the graph and increases to the right side of the graph.

[0048] from Figure 6 The seventh graph from the top is a graph indicating whether automatic engine stop and start are prohibited based on all conditions that are the basis for prohibiting automatic engine stop. The vertical axis represents the automatic engine stop prohibition state, and the automatic engine stop is prohibited when the trace is at a higher level near the vertical axis arrow. When the trace is near the horizontal axis, the automatic engine stop and start are not prohibited. The horizontal axis represents time. Time starts on the left side of the graph and increases to the right side of the graph.

[0049] At time t0, the estimated engine cranking time is greater than threshold 602 and the battery state of charge is less than threshold 604. The engine cranking time estimation algorithm A is activated so that the estimated and predicted maximum engine cranking current or the estimated engine cranking energy is not estimated. Because the battery state of charge is low, the predicted maximum engine cranking current is a lower intermediate level. Because the battery state of charge is less than threshold 604, the condition for automatically stopping the engine in response to the battery state of charge (SOC) does not exist. Because the battery state of charge is less than threshold 604, automatic engine stop is prohibited so that the engine will continue to run (e.g., burn air and fuel).

[0050] Between time t0 and time t1, the battery state of charge increases and the estimated engine cranking time based on the predicted engine cranking current decreases as the predicted engine cranking current increases. The battery state of charge may be increased by the engine charging the battery or by regenerative braking (not shown). The engine cranking algorithm A remains active and an automatic engine stop condition based on the battery state of charge is not present. Since the battery state of charge remains low, the engine automatic engine stop remains inhibited.

[0051] At time t1, the battery state of charge is equal to or greater than threshold 604. Additionally, in this example, the estimated engine start cranking time decreases to be equal to or less than threshold 602 because the predicted engine start cranking current increases in response to the increase in the battery state of charge. Additionally, a trace indicating whether an automatic engine stop condition exists based on the battery state of charge transitions from a lower level to a higher level to indicate that the battery state of charge is high enough to allow automatic engine stopping. Additionally, the automatic engine stop and start inhibit trace transitions to a lower level to indicate that automatic engine stopping and starting are permitted. Because the battery state of charge is greater than threshold 604 and because the estimated engine start cranking time is less than threshold 602, automatic engine starting and stopping is permitted. The estimated engine start cranking time may be a function of the engine peak start cranking current. Additionally, the engine start cranking current may be a function of the starter motor internal resistance, the internal battery resistance, the battery open circuit voltage, and as described with respect to Figure 7 functions of other electrical system parameters discussed in further detail.

[0052] Between time t1 and time t2, the predicted engine start cranking time decreases and then increases. The estimated engine start cranking time can increase and decrease in response to the predicted peak engine start cranking current, and the peak engine start cranking current can vary with engine electrical system parameters that can change over time, including but not limited to internal battery resistance, starter motor internal resistance, and battery open circuit voltage. The battery state of charge remains high and the engine start cranking algorithm A remains effective. An automatic engine stop condition based on the battery state of charge is present, and the automatic engine stop prohibition is not asserted, so that the engine can be automatically stopped and restarted.

[0053] At time t2, the estimated engine cranking time increases to a time equal to or greater than threshold 602. The estimated engine cranking time increases as the predicted peak engine cranking current decreases. The battery state of charge remains high and the engine cranking algorithm A remains effective. An automatic engine stop condition based on the battery state of charge exists, but the automatic engine stop prohibition is enabled, making it impossible to automatically stop and restart the engine. The increased engine cranking time may be objectionable to vehicle occupants, thereby prohibiting automatic engine stopping and starting. In this way, the vehicle can be automatically stopped and started when the engine cranking time is always less than a predetermined threshold. The internal resistance of the starter motor can increase and decrease in response to the frequency of engine starting and stopping in order to adjust the predicted engine start time.

[0054] Between time t2 and time t3, the predicted engine cranking current decreases and then increases, causing the estimated engine cranking time to increase and then decrease. The battery state of charge remains above threshold 604, and the engine cranking algorithm A remains activated. The automatic engine stop responsive to the battery state of charge remains in effect, but the automatic engine stop inhibit is also activated, causing the automatic engine stop to be inhibited because the estimated engine cranking time exceeds threshold 602.

[0055] At time t3, the estimated engine cranking time is equal to or less than threshold 602, so that the automatic engine stop inhibition is not activated. Therefore, the engine can be stopped and started automatically. The predicted peak or maximum engine cranking current has increased to a level where the estimated engine cranking time is less than threshold 602. Since the battery state of charge is greater than threshold 604, an engine stop condition responsive to the battery state of charge exists. In addition, the engine cranking algorithm A remains in effect so that the peak engine cranking current is determined.

[0056] Between time t3 and time t4, a sequence interruption occurs and engine start cranking algorithm B is activated. Algorithm B does not predict peak engine start cranking current. Instead, algorithm B determines a predicted engine start cranking energy. Algorithm B also estimates an engine start cranking time based on the predicted engine start cranking energy. The engine start cranking time is greater than threshold 602, so that the automatic engine stop prohibition is effective and activated, so that automatic engine stop and start are prohibited. The battery state of charge is less than threshold 604, which results in an automatic engine stop condition in response to the absence of a battery state of charge. The predicted engine start cranking energy is lower than threshold 606, so that the automatic engine stop prohibition is activated.

[0057] At time t4, the predicted engine cranking energy has increased to a value equal to or greater than threshold 606, and the battery state of charge has increased to a value equal to or greater than 604. The automatic engine stop condition in response to the battery state of charge changes the state from not active to active, and the automatic engine stop inhibit changes the state from active to inactive, so that automatic engine stops and starts are permitted based on the battery state of charge and the estimated engine cranking time. The estimated engine cranking time has decreased in response to the increase in predicted engine cranking energy.

[0058] Between time t4 and time t5, the battery state of charge continues to increase and the estimated engine cranking time also decreases and then increases near time t5. The predicted engine cranking energy increases and then decreases near time t5. The engine cranking algorithm B remains activated. The automatic engine stop inhibit remains deactivated, allowing automatic stopping and starting of the engine. An automatic engine stop condition based on the battery state of charge is present, allowing automatic stopping and starting of the engine.

[0059] At time t5, the estimated engine cranking time has increased to a level equal to or greater than threshold 602, causing the automatic engine stop and start inhibit state to change from not active to active. Therefore, even though the battery state of charge is greater than threshold 604, automatic engine stops and starts are inhibited. The predicted engine cranking energy has also decreased. Figure 7 The predicted engine cranking energy may be increased or decreased based on other electrical system parameters described in more detail in the description of . Engine cranking algorithm B remains active, and the automatic engine stop inhibit state changes from never active to active. Since the battery state of charge is greater than threshold 604, the automatic engine stop and start state responsive to the battery state of charge remains active. Therefore, automatic engine starts and stops are inhibited because the automatic engine stop inhibit state is active.

[0060] Between time t5 and time t6, the predicted engine cranking energy decreases and then increases, causing the estimated engine cranking time to increase and then decrease. The battery state of charge remains above threshold 604, and the engine cranking algorithm B remains activated. The automatic engine stop responsive to the battery state of charge remains in effect, but the automatic engine stop inhibit is also activated, causing the automatic engine stop to be inhibited because the estimated engine cranking time exceeds threshold 602.

[0061] At time t6, the estimated engine start cranking time is equal to or less than threshold 602, so that the automatic engine stop prohibition is not activated. Therefore, the engine can be automatically stopped and started. The predicted engine start cranking energy has increased to a level where the estimated engine start cranking time is less than threshold 602. Since the battery state of charge is greater than threshold 604, an engine stop condition responsive to the battery state of charge exists. In addition, the engine start cranking algorithm B remains effective so that the engine start cranking energy is determined.

[0062] In this way, either Algorithm A or Algorithm B may be activated to provide an estimate of the engine cranking time. The estimated engine cranking time may be the basis for enabling or disabling automatic engine stops and starts so that a vehicle occupant may find vehicle operating conditions objectionable.

[0063] Reference now Figure 7 , a method for operating a vehicle is shown. At least some portions of method 700 may be implemented as executable controller instructions stored in a non-volatile memory. Additionally, some portions of method 700 may be actions taken in the physical world to transform the operating state of an actuator or device. Figure 7 The method may be incorporated as executable instructions stored in a non-volatile memory Figure 1 and Figure 2 in the system.

[0064] At 702, method 700 determines whether a vehicle occupant (e.g., driver) has requested and started the engine of the vehicle. In one example, a bit in the memory indicates whether the vehicle has been started by the occupant. The bit can be set to indicate that the vehicle is started in response to a key switch, button, or remote starter applied to start the vehicle. If method 700 determines that the engine has been started (e.g., combusted air and fuel), the answer is yes and method 700 proceeds to 704. Otherwise, the answer is no and method 700 proceeds to exit.

[0065] At 704 , method 700 determines vehicle operating conditions including, but not limited to, battery state of charge (SOC), battery internal resistance, starter motor internal resistance (e.g., resistance of windings), driver demand torque, engine speed, vehicle speed, etc. Method 700 proceeds to 706 after determining vehicle operating conditions.

[0066] At 706, method 700 determines whether the battery SOC is greater than a threshold SOC. At lower battery SOC levels, there may not be enough charge to start the engine (e.g., after accelerating the engine from the most recent zero speed condition, rotating the engine from zero speed to the first combustion event). Therefore, if the battery SOC is less than the threshold, it may be desirable to inhibit automatic engine stop (e.g., stop the engine without the driver requesting the engine stop through a dedicated engine stop input device (such as an ignition switch or button) having the sole function of requesting engine start and stop, including stopping spark and fuel delivery to the engine). If the battery SOC is greater than the threshold, the answer is yes and method 700 proceeds to 708. Otherwise, the answer is no and method 700 proceeds to 712.

[0067] In some examples, method 700 may also require that the engine temperature be greater than a threshold temperature in order for method 700 to proceed to 708. Additionally, method 700 may require that the actual total amount of time that the engine is stopped (e.g., not spinning) be less than a threshold amount of time in order for method 700 to proceed to 708. If these conditions are not met, method 700 proceeds to 712.

[0068] At 708, method 700 determines whether the driver demand torque is less than a threshold. In the case of a reference output function or table that empirically determines the driver demand torque, the driver demand torque may be determined by the accelerator pedal position and the vehicle speed. If method 700 determines that the driver demand torque is less than the threshold, the answer is yes and method 700 proceeds to 710. Otherwise, the answer is no and method 700 proceeds to 712. At lower driver demands where the engine torque is not necessary to save fuel, the engine may be automatically stopped and started.

[0069] At 710, method 700 performs the following steps according to Figure 8The method 700 determines whether to prohibit automatic engine stopping. If it can be expected or predicted that the engine start rotation time will exceed a threshold time amount, the automatic engine stop can be prohibited. When the engine start rotation time is longer than the threshold time amount, the vehicle occupant may become irritated or may experience a lower level of driving satisfaction. Therefore, when the engine start rotation during the automatic engine start after the engine has been automatically stopped (e.g., not rotating and not burning air and fuel) is expected or predicted to continue for more than a threshold time amount, the automatic engine stop and start can be prohibited. If method 700 determines that the predicted engine start rotation time is greater than the threshold time amount, the answer is yes and method 700 proceeds to 712. Otherwise, method 700 proceeds to 714. The predicted engine start rotation time can be determined when the engine is rotating and burning air and fuel.

[0070] At 712, method 700 prohibits automatic engine stops and automatic engine starts (e.g., starting a stopped engine without the driver requesting an engine start via a dedicated engine start input device (such as an ignition switch or button) having the sole function of requesting engine starts and stops). Therefore, even if the battery SOC is greater than a threshold and the driver demand torque is less than a threshold, automatic engine starts and stops are prohibited. The engine can still be stopped and started by the vehicle driver or occupant requesting an engine start or stop via a dedicated engine start or stop input device (e.g., a key switch or button). By prohibiting automatic engine stops and starts, vehicle occupants may not be subjected to hearing long engine start cranking times, which can improve the vehicle driving experience. Method 700 proceeds to exit.

[0071] At 714, method 700 allows or permits automatic engine stopping and starting subject to battery SOC, driver demand torque, and other engine and vehicle operating conditions. If an automatic engine stop condition is present, the engine can be automatically stopped and started. For example, if certain conditions are met, the engine of the vehicle can be automatically stopped by a vehicle controller. The conditions may be different for different driving conditions and vehicle configurations. In one example, in the case where the vehicle is not a hybrid vehicle, the controller can automatically stop the engine without the driver applying input to a device (e.g., an ignition switch or ignition button) having the sole function of starting and / or stopping the engine of the vehicle. The engine can be automatically stopped if the driver demand torque is less than a threshold (such as a released accelerator pedal), the vehicle brake pedal is applied, the battery SOC is greater than a threshold, and the vehicle speed is less than a threshold speed. In some cases, the vehicle may be moving when the engine is shut down and stopped; while in other cases, the vehicle may be stopped when the engine is shut down and stopped. If the vehicle is a hybrid vehicle, the engine can be automatically shut down and stopped when the motor has the ability to provide the driver demand torque and the battery state of charge is greater than a threshold. Of course, the engine can be automatically stopped in response to other vehicle conditions.

[0072] If the engine has been automatically stopped, the engine can be automatically started without the vehicle occupants specifically manipulating an input device with a dedicated unique function of starting and / or stopping the engine. If the engine is not in a hybrid vehicle, in response to the driver releasing the brake pedal when the vehicle is stopped, the engine can be automatically started by engaging the starter, rotating the engine at a starting rotation speed, and supplying fuel and spark to the engine. In addition, in response to the driver releasing the applied accelerator when the brake pedal is applied or not applied, the engine can be automatically started by engaging the starter, rotating the engine at a starting rotation speed, and supplying fuel and spark to the engine. If the engine is in a hybrid vehicle, in response to the driver demanding torque exceeding a threshold, the battery SOC being less than a threshold, and the exhaust device temperature being reduced to less than a threshold temperature, the engine can be automatically started (e.g., including rotating, supplying sparks and fuel) from a stopped state. Of course, the engine can be automatically started in response to other vehicle conditions.

[0073] The method 700 may also collect data during the engine starting sequence. For example, the method 700 may collect data on the variables starting rotation I_starting rotation, V 开路电压 , R_battery, R_starter, E_starter, V_battery, I_starter, E_starter rotation, E_ohm heat and Figure 7 and Figure 8 Other variables mentioned in the description are stored in transient memory or non-transient memory. Method 700 proceeds to exit.

[0074] Reference now Figure 8 , a method for selectively inhibiting automatic engine stopping and starting is shown. At least some portions of method 800 may be implemented as executable controller instructions stored in non-volatile memory. Additionally, some portions of method 800 may be actions taken in the physical world to transform the operating state of an actuator or device. Figure 8 The method may be incorporated as executable instructions stored in a non-volatile memory Figure 1 and Figure 2 in the system.

[0075] At 802, method 800 determines the vehicle configuration and the vehicle state. The vehicle configuration can be based on the type of sensors used to determine vehicle operating conditions, such as starter motor winding resistance, internal battery resistance, battery open circuit voltage, starter current, and other electrical system properties. The vehicle configuration can be stored as a variable value stored in a controller non-transient memory. In addition, method 800 can determine the state of the vehicle. The state of the vehicle can include determining whether any of the various vehicle sensors is degraded. For example, the state can identify whether the battery voltage or current sensor is degraded. After determining the vehicle state and vehicle configuration, method 800 proceeds to 804.

[0076] At 804, method 800 selects an engine start rotation and monitoring algorithm to be activated. The selection of the engine start rotation and monitoring algorithm is selected in response to the vehicle configuration and status. If the vehicle configuration supports estimating the engine start rotation energy and its various parameters, then if the vehicle status indicates that the sensor used to determine the engine start rotation energy is not degraded, algorithm B can be selected and activated. If the vehicle configuration does not support estimating the engine start rotation (for example, the vehicle is not configured with a specific sensor) or if the sensor supporting algorithm B is degraded, method 800 can select and activate algorithm A. If method 800 activates algorithm A, method 800 proceeds to 806. Otherwise, method 800 proceeds to 820 and selects and activates algorithm B.

[0077] At 806, method 800 estimates the maximum or peak engine cranking current. In one example, method 800 estimates the maximum engine cranking current supplied by the battery to the starter motor by the following equation:

[0078] I_Starting rotation = V 开路电压 / (R_battery+R_starter)

[0079] Where I_Start is the maximum current supplied by the battery to the engine starter, V 开路电压V can be determined by monitoring the battery voltage when the battery is open circuit from the electric consumer. 开路电压 , can be measured by measuring the battery open circuit voltage and the battery voltage when supplying current to the load (for example, V 开路电压 -V L / I, where V 开路电压 is the open circuit battery voltage, V L R_BATTERY may be determined by providing a voltage to the starter winding and dividing the voltage by the current flowing through the starter winding or another known method. Method 800 proceeds to 808 after estimating the engine cranking current. It should be noted that the engine cranking current is estimated before the engine is stopped while the engine is spinning so that if the estimated engine cranking time exceeds a threshold amount of time, the engine stop may be prohibited.

[0080] At 808, method 800 estimates the engine cranking time (e.g., the amount of time between the time the engine starts to rotate from a stop and the time the engine accelerates or maintains engine speed under the engine's own power). In one example, the maximum engine cranking current index or reference such as Figure 5 The function shown in FIG. 800 is a function that outputs a predicted or estimated engine cranking time in response to the maximum engine cranking current. In addition, in other examples, the table or function may be referenced based on the engine temperature so that the predicted or estimated cranking time is compensated for the engine temperature. Method 800 proceeds to 810.

[0081] At 810, method 800 determines whether the predicted engine cranking time is less than a threshold amount of time. The threshold amount of time may be a fixed value or a value that varies with other vehicle operating conditions. If method 800 determines that the predicted engine cranking time is less than the (LT) threshold, the answer is yes and method 800 proceeds to 814. Otherwise, the answer is no and method 800 proceeds to 812.

[0082] At 814 , method 800 permits or enables automatic engine stopping and starting subject to battery SOC, vehicle speed, and constraints other than estimated engine cranking time. Method 800 proceeds to 816 .

[0083] At 812 , method 800 inhibits automatic engine stopping so that vehicle occupants may not be subjected to longer engine cranking times during automatic engine starting. Thus, the vehicle driving experience may be improved. Method 800 proceeds to 816 .

[0084] At 816, method 800 determines whether the engine is stopped and whether the engine has been automatically stopped. If so, the answer is yes and method 800 proceeds to 818. Otherwise, the answer is no and method 800 proceeds to exit. Method 800 can determine that the engine is stopped and the engine is automatically stopped based on a bit or variable stored in memory.

[0085] At 818 , method 800 continues to estimate or predict engine cranking time when the engine is stopped by activating either algorithm A or algorithm B. Method 800 proceeds to 820 .

[0086] At 820, method 800 judges whether the predicted engine cranking time is greater than (GT) threshold amount of time. If so, the answer is yes and method 800 proceeds to 822. Otherwise, the answer is no and method 800 proceeds to exit.

[0087] At 822, the method automatically starts the engine by cranking the engine and supplying spark and fuel to the engine. By automatically starting the engine, excessive engine cranking events can be avoided and the battery SOC can be increased. The method 800 proceeds to exit after automatically starting the engine.

[0088] At 830 , method 800 estimates engine starting cranking energy according to the following equation:

[0089] E_starter = V_battery * integral of I_starter during cranking = E_cranking + E_ohm-heat

[0090] Where E_cranking is the energy used to crank the engine shaft; E_ohm-heat is the heat generated in the starter circuit that is not used to crank the engine shaft; V_battery is the voltage between the battery terminals; I_starter is the current of the starter during cranking, which is approximately the same as the battery current. During engine cranking, electrical energy is transferred from the battery to the starter. The integral can be based on the time from cranking the engine from zero speed during the most recent engine stop to the first combustion event since the most recent engine stop. The relationship between the battery parameters and the crankshaft energy can be calculated using the following simplified equation:

[0091] I_starter = V_open circuit voltage / (R_battery+R_starter+X_starter)

[0092] V_battery = V_open circuit voltage – I_starter * R_battery

[0093] P_starter = V_battery * I_starter

[0094] P_starting speed = P_starter – I_starter * I_starter * R_starter

[0095] E_starter = integral of P_starter during cranking time

[0096] E_Starting rotation = integral of P_Starting rotation during the starting rotation time

[0097] Where V_battery is the battery voltage curve during the cranking cycle; P_starter is the total electrical power provided from the battery to the starter; P_starter_cycle is the power provided from the battery to the starter, excluding starter ohmic heating; E_starter is the total energy provided from the battery to the starter during the cranking cycle; E_starter_cycle is the energy provided from the battery to the starter during the cranking cycle, excluding starter ohmic heating; and X_starter is the starter impedance curve. The I_starter equation is a simplified equation for estimating the battery current curve in the next warm cranking cycle. The starter impedance X_starter is a time-based curve and is measured in previous successful warm cranking cycles and saved in the memory of the controller. E_starter_cycle is the estimated available energy provided by the battery to the starter shaft during the next warm cranking cycle. At 832, E_starter_cycle is used to determine the predicted cranking time. For a successful warm start crank, the available energy from the battery (E_crank) must be greater than or equal to a threshold value E_crank_min, where E_crank_min is determined based on the measured battery voltage and current of a previous successful warm start crank. Thus, the engine crankshaft can reach the desired speed in the desired time.

[0098] The voltage, current and starter impedance curves of multiple previous successful warm engine starting rotations are recorded and stored in the controller. The E_starting rotation value can be calculated based on the data of multiple previous successful warm engine starting rotations. Then, based on the E_starting rotation and the Figure 4 The predicted engine cranking time for the next engine cranking is calculated using the correlation shown. In a first order approximation, the predicted cranking time for the next warm start cranking is estimated by the following equation:

[0099] T_starting rotation estimate = T_starting rotation estimate * E_starting rotation_next starting rotation / E_starting rotation_previous starting rotation

[0100] Wherein T_crank estimate is the estimated crank time in the next warm crank, used to enable / disable automatic engine stop; T_crank estimate is the measured crank time during the last previous warm engine crank period; E_crank_next crank is the estimated engine crank energy based on the estimated crank voltage V_battery and crank current I_starter; E_crank_previous crank is the measured engine crank energy based on the measured engine crank battery voltage and engine crank current. In some examples, the battery crank voltage curve, engine crank current curve, and corresponding engine crank time in multiple previous warm engine crank events are saved and used to estimate the next warm crank time. Method 800 proceeds to 810 after determining the predicted engine crank time. The predicted engine crank time and engine crank energy can be determined while the engine is spinning and burning air and fuel.

[0101] In this way, the predicted engine cranking time can be determined based on the maximum engine cranking current or predicted energy used to crank the engine. If the vehicle is a low-cost configuration, algorithm A can be activated. Alternatively, if the sensor is degraded, algorithm A can be activated because it is less complex. If the vehicle has a larger sensor group, algorithm B can be activated.

[0102] therefore, Figure 7 and Figure 8 A method of vehicle operation is provided, comprising: automatically stopping and starting an engine; and prohibiting automatic stopping of the engine in response to an estimated engine cranking time exceeding a threshold. The method comprises, wherein the estimate of the engine cranking time is based on the electrical energy consumed to crank the engine from a most recent engine stop to a first combustion event since the most recent engine stop. The method comprises, wherein automatically stopping the engine comprises automatically terminating fuel flow to the engine and terminating engine rotation, and further comprises starting the engine in response to the estimated engine cranking time exceeding the threshold after the engine has been automatically stopped during the most recent engine stop in which the engine stopped rotating. The method comprises, wherein the estimate of the engine cranking time is based on the amount of electrical cranking current consumed to crank the engine. The method comprises, wherein the estimate of the engine cranking time is performed while the engine is operating. The method further comprises, further prohibiting automatic engine stopping in response to a battery state of charge. The method comprises, wherein the estimated engine cranking time is based on an internal resistance of a battery. The method comprises, wherein the estimated engine cranking time is also based on a resistance of a starter motor.

[0103] Figure 7 and Figure 8 The method also provides a vehicle operation method, which includes: automatically stopping and starting an engine; predicting an engine cranking time; and prohibiting automatic stopping of the engine in response to the predicted engine cranking time exceeding a threshold. The method also includes predicting a maximum battery current during the engine cranking. The method also includes associating the predicted maximum battery current during the engine cranking with the predicted engine cranking time. The method includes, wherein the predicted engine cranking time is responsive to the resistance of the starter motor winding. The method includes, wherein the predicted engine cranking time is responsive to the internal resistance of the battery. The method includes, wherein the predicted engine cranking time is responsive to the open circuit voltage of the battery. The method includes, wherein the predicted engine cranking time is responsive to the heat generated in the starter motor.

[0104] Note that the exemplary control and estimation routines included herein can be used with various engine and / or vehicle system configurations. The control methods and routines disclosed herein can be stored as executable instructions in a non-transient memory and can be executed by a control system that includes a combination of a controller and various sensors, actuators, and other engine hardware. The specific routines described herein can represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multi-tasking, multi-threading, etc. Therefore, the various actions, operations, and / or functions shown may be performed in the order shown, performed in parallel, or omitted in some cases. Similarly, the processing sequence is not required to achieve the features and advantages of the exemplary embodiments described herein, but is provided for ease of illustration and description. One or more of the actions, operations, and / or functions shown may be repeatedly performed depending on the specific strategy used. In addition, at least a portion of the described actions, operations, and / or functions can graphically represent the code in the non-transient memory of a computer-readable storage medium to be programmed into the control system. The control action can also transform the operating state of one or more sensors or actuators in the physical world when the described action is implemented by executing instructions in a system including a combination of various engine hardware components and one or more controllers.

[0105] This ends the specification. The reading of this specification by those skilled in the art will suggest many changes and modifications without departing from the spirit and scope of this specification. For example, I3, I4, I5, V6, V8, V10 and V12 engines operating in natural gas, gasoline, diesel or alternative fuel configurations may use this specification with benefit.

Claims

1. A vehicle operating method, comprising: Automatically stop and start the engine; as well as Automatically stopping the engine is inhibited in response to an estimated engine cranking time exceeding a threshold. 2 . The method of claim 1 , wherein the estimate of the engine cranking time is based on an amount of electrical energy consumed to crank the engine from a most recent engine stop to a first combustion event since the most recent engine stop.

3. The method of claim 1 , wherein automatically stopping the engine comprises terminating fuel flow to the engine and terminating engine rotation, and further comprising: The engine is automatically started in response to the estimated engine cranking time exceeding the threshold after the engine has been automatically stopped. 4 . The method of claim 1 , wherein the estimate of the engine cranking time is based on a maximum magnitude of the engine cranking current. The method of claim 4 , wherein the estimation of the engine cranking time is performed while the engine is operating. The method of claim 1 , further comprising inhibiting automatic engine stopping in further response to a battery state of charge. 7 . The method of claim 1 , wherein the estimated engine cranking time is based on an internal resistance of a battery. 8 . The method of claim 7 , wherein the estimated engine cranking time is further based on a resistance of a starter motor.

9. A vehicle system comprising: an engine including a starter motor; a battery that selectively supplies charge to the starter motor; as well as A controller comprising executable instructions stored in a non-volatile memory, the instructions being used to: predict an engine start rotation time while the engine is rotating, and prohibit automatic stopping of the engine in response to the predicted engine start rotation time exceeding a threshold; and automatically start the engine in response to the predicted engine start rotation time exceeding the threshold when the engine is stopped due to an automatic engine stop. 10 . The vehicle system of claim 9 , further comprising instructions for predicting the engine cranking time based on a maximum engine cranking current.

11. The vehicle system of claim 9 further comprising instructions for predicting a cranking time of the engine based on an energy used to crank the engine.

12. The vehicle system of claim 9, wherein the engine cranking time is the time from when the engine is rotated from zero speed to a first combustion event since a last engine stop.

13. The vehicle system of claim 9, wherein the engine cranking time is based on resistance of a starter motor winding.

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