Procedure and system for starting a hybrid vehicle

Abstract

Procedure, comprehensive: Operating a power engine (10) at a substantially constant air mass flow and ignition timing adjustment in response to a catalyst temperature below a threshold; Changing a power machine torque (T DES_ENG ) with changing engine speed while simultaneously operating the engine (10) at a substantially constant air mass flow; and Providing a driver request torque (T DD ) via a power machine torque (T DES_ENG ) and engine torque (T MOT ) while simultaneously operating the power engine (10) at the substantially constant air mass flow.

Description

Area

[0001] This description relates to a method and a system for starting a power unit of a hybrid vehicle. The methods can be used in particular for hybrid vehicles that include a starter / generator integrated into the powertrain. Background and brief description

[0002] Hybrid vehicles may have to comply with emissions regulations for hydrocarbons, carbon monoxide, and nitrogen oxides. One way to meet emissions regulations is to couple a three-way catalytic converter to one of the hybrid vehicle's power units, so that the power unit's emissions are oxidized and reduced to more desirable gases. But even with a three-way catalytic converter, a hybrid vehicle may still fail to meet emissions regulations because the three-way converter may need to reach a start-up temperature (i.e., a temperature at which the catalyst efficiency reaches a threshold efficiency) before it can process power unit exhaust gases. One way to reduce the time it takes for a converter to reach start-up temperature is to adjust the power unit's ignition timing from minimum advance for best torque (MBT) to a lower ignition advance.The ignition timing can be retarded (minimum spark advance for best torque). By retarding the ignition timing, exhaust gases can transfer additional heat to the engine's exhaust system and its components. However, retarding the engine's ignition timing alone may not be sufficient to heat a catalytic converter to its activation temperature quickly enough to meet emissions regulations. Therefore, it would be desirable to provide a means of reaching the catalytic converter's activation temperature more quickly.

[0003] Various operating procedures for internal combustion engines are known from the publication Richard Basshuysen, Fred Schäfer: Handbook of Internal Combustion Engines. Wiesbaden, Springer Vieweg, 2014 (7th edition) - ISBN 2628-1058.

[0004] The inventors in question have recognized the aforementioned disadvantages and have developed a method comprising: operating a power engine at a substantially constant air mass flow and adjusting the ignition timing in response to a catalyst temperature below a threshold; changing a power engine torque as the power engine speed changes while simultaneously operating the power engine at the substantially constant air mass flow; and providing a driver request torque via a power engine torque and an engine torque while simultaneously operating the power engine at the substantially constant air mass flow.

[0005] By operating a power unit with a substantially constant air mass flowing through it, and varying the power unit torque as the engine speed changes, it is possible to achieve the technical result of rapidly heating a catalyst while simultaneously generating the desired driver-demand torque. In particular, the engine air mass can be selected to provide a desired rate of heat energy from the power unit to the catalyst, ensuring that the catalyst activates within a desired timeframe, even with changing vehicle speed and driver-demand torque.A motor coupled to the power unit can increase or decrease the power unit's torque to provide driver-requested torque to a torque converter pump wheel as the power unit's speed changes during vehicle acceleration and deceleration. In this way, airflow through the power unit can be kept essentially constant even as the power unit's speed changes, allowing a catalytic converter to engage in a repeatable manner when a vehicle accelerates or decelerates.

[0006] The present description can offer several advantages. In particular, the approach can improve vehicle emissions. Furthermore, the approach can improve the vehicle's operating behavior during engine start-up. Additionally, the approach allows for more precise control of the air-fuel ratio while the engine's emission components are warmed up to operating temperature.

[0007] The aforementioned advantages, as well as other advantages and features of the present description, are easily recognizable from the following detailed description alone or in conjunction with the accompanying drawings.

[0008] It is understood that the foregoing summary is provided to present, in simplified form, a selection of concepts that are described in more detail in the full description. It is not intended to reveal any decisive or essential features of the claimed invention, the scope of which is defined solely by the claims following the full description. Furthermore, the claimed invention is not limited to implementations that resolve any of the disadvantages mentioned above or in any part of this disclosure. Brief description of the drawings

[0009] The advantages described herein are better understood by reading an example of an embodiment referred to herein as the "Detailed Description", either alone or with reference to the drawings, wherein: Fig. 1 is a schematic representation of a power machine; Fig. 2 represents an exemplary powertrain configuration of a vehicle; Fig. 3 represents an exemplary operating sequence of a hybrid vehicle; and Fig. 4 represents an exemplary method for operating a powertrain of a hybrid vehicle. Detailed description

[0010] The present invention relates to the improvement of hybrid vehicle emissions after a power engine start. The hybrid vehicle can comprise a power engine, as shown in Fig. 1 shown. Furthermore, the power unit can be included in a drivetrain of the hybrid vehicle, as shown in Fig. 2 shown. Engine emissions can be reduced by heating a catalyst through the operation of an engine and a driveline integrated starter / generator (DISG), as shown in the sequence of Fig. 3 shown, can be reduced. The power unit and the DISG can be reduced according to the procedure of Fig. 4 in the system of Fig. 1 and Fig. 2. be operated in such a way as to provide the operational process that is in Fig. 3 is shown.

[0011] With reference to Fig. 1 is a power engine 10 with internal combustion 10, comprising a plurality of cylinders, of which in Fig. Figure 1 shows a cylinder controlled by an electronic engine control unit 12. The engine 10 comprises a combustion chamber 30 and cylinder walls 32 with a piston 36 positioned therein, which is connected to a crankshaft 40. A flywheel 97 and a ring gear 99 are coupled to the crankshaft 40. The starter 96 (e.g., a low-voltage electric machine (operated at less than 30 volts)) comprises a pinion shaft 98 and a pinion 95. The pinion shaft 98 can selectively advance the pinion 95 to engage with the ring gear 99. The starter 96 can be mounted directly on the front or rear of the engine. In some examples, the starter 96 can selectively supply torque to the crankshaft 40 via a belt or chain. In one example, the starter 96 is in a ground state when it is not engaged with the engine crankshaft.The combustion chamber 30 is represented by an intake valve 52 and an exhaust valve 54, which communicate with an intake manifold 44 and an exhaust manifold 48, respectively. Each intake and exhaust valve can be actuated by an intake cam 51 and an exhaust cam 53. The position of the intake cam 51 can be determined by the intake cam sensor 55. The position of the exhaust cam 53 can be determined by the exhaust cam sensor 57.

[0012] In the illustration, the fuel injector 66 is positioned to inject fuel directly into cylinder 30, a process known to those skilled in the art as direct injection. Alternatively, fuel can be injected into an intake port, a process known to those skilled in the art as port injection. The fuel injector 66 supplies liquid fuel in a pulse width ratio from the control unit 12. The fuel is supplied to the fuel injector 66 by a fuel system (not shown) comprising a fuel reservoir, a fuel pump, and a fuel distribution pipe (not shown).

[0013] Furthermore, the intake manifold 44 is shown connected to a turbocharger compressor 162. A shaft 161 mechanically couples the turbocharger turbine 164 to the turbocharger compressor 162. An optional electronic throttle valve 62 adjusts the position of a throttle plate 64 to regulate airflow from the air intake 42 to the compressor 162 and intake manifold 44. In one example, a two-stage high-pressure fuel system can be used to generate higher fuel pressures. In some examples, the throttle valve 62 and the throttle plate 64 can be positioned between the intake valve 52 and the intake manifold 44, such that the throttle valve 62 is an intake port throttle valve.

[0014] A distributorless ignition system 88 provides an ignition spark for the combustion chamber 30 via a spark plug 92 in response to the control unit 12. A universal exhaust gas oxygen (UEGO) sensor 126 is shown coupled to the exhaust manifold 48 upstream of a catalytic converter 70. Alternatively, a dual-state exhaust gas oxygen sensor can be used instead of the UEGO sensor 126.

[0015] The converter 70 can contain multiple catalyst blocks in one example. In another example, multiple exhaust gas purification systems, each with multiple blocks, can be used. The converter 70 can also be a three-way catalyst in one example.

[0016] Control 12 is in Fig. Figure 1 is represented as a conventional microcomputer comprising: a microprocessor unit 102, input / output ports 104, a read-only memory 106 (e.g., a non-transitory memory), a random-access memory 108, a buffer memory 110, and a conventional data bus. The controller 12 is shown to receive, in addition to the signals discussed previously, various signals from sensors coupled to the engine 10, including: an engine coolant temperature (ECT) from a temperature sensor 112 coupled to a cooling sleeve 114; a position sensor 134 coupled to an accelerator pedal 130 to measure a force exerted by a foot 132; and a position sensor 154 coupled to the brake pedal 150 to measure a force exerted by a foot 152. a measurement of engine manifold pressure (MAP for English).manifold pressure) from a pressure sensor 122 coupled to the intake manifold 44; an engine position sensor from a Hall-effect sensor 118 measuring the position of the crankshaft 40; a measurement of the mass of air entering the engine from a sensor 120; and a measurement of the throttle position from a sensor 58. The barometric pressure can also be acquired for processing by the controller 12 (sensor not shown). In a preferred aspect of the present description, the engine position sensor 118 generates a predetermined number of uniformly spaced pulses at each revolution of the crankshaft, from which the engine speed (RPM) can be determined.

[0017] In some examples, the combustion engine in a hybrid vehicle can be coupled with an electric motor / battery system, as in Fig. Figure 2 is shown. Furthermore, other engine configurations, such as a diesel engine, can be used in some examples.

[0018] In operation, each cylinder within the engine 10 typically undergoes a four-stroke cycle: the cycle comprises the intake stroke, the compression stroke, the power stroke, and the exhaust stroke. During the intake stroke, the exhaust valve 54 generally closes, and the intake valve 52 opens. Air is introduced into the combustion chamber 30 via the intake manifold 44, and the piston 36 moves toward the bottom of the cylinder to increase the volume within the combustion chamber 30. The position at which the piston 36 is near the bottom of the cylinder and at the end of its stroke (e.g., when the combustion chamber 30 has reached its maximum volume) is typically referred to by those skilled in the art as bottom dead center (BDC). During the compression stroke, the intake valve 52 and the exhaust valve 54 are closed. The piston 36 moves toward the cylinder head to compress the air in the combustion chamber 30.The point at which the piston 36 is closest to the cylinder head at the end of its stroke (e.g., when the combustion chamber 30 has its smallest volume) is typically referred to by those skilled in the art as top dead center (TDC). In a process referred to below as injection, fuel is introduced into the combustion chamber. In a process referred to below as ignition, the injected fuel is ignited by known ignition devices, such as the spark plug 92, resulting in combustion. During the power stroke, the expanding gases push the piston 36 back towards the top dead center (BDC). The crankshaft 40 converts piston motion into torque of the crankshaft. Finally, during the exhaust stroke, the exhaust valve 54 opens to discharge the burnt air-fuel mixture to the exhaust manifold 48, and the piston returns to the TDC.It should be noted that the foregoing is presented only as an example, and that the timing of the opening and / or closing of the intake and exhaust valves may vary to provide, for example, positive or negative valve overlap, late closing of the intake valve, or various other examples.

[0019] Fig. Figure 2 is a block representation of a vehicle 225 with a powertrain 200. The powertrain of Fig. 2 includes the power machine 10, which is in Fig. Figure 1 shows the drive train 200. The power unit 10 can be driven by the power unit 10. The power unit 10 can be equipped with a power unit starting system, which is shown in Fig. 1 is shown, or can be started via a starter / generator (DISG) 240 integrated into the drivetrain. The DISG 240 (e.g., a high-voltage electric machine (operated at more than 30 volts)) can also be referred to as an electric machine, motor, and / or generator. Furthermore, the torque of the power machine 10 can be adjusted via a torque actuator 204, such as a fuel injector, a throttle valve, etc.

[0020] An output torque from the power unit can be transmitted via a dual-mass flywheel 215 to an input side of the drivetrain disconnect clutch 236. The disconnect clutch 236 can be actuated electrically or hydraulically. The downstream side of the disconnect clutch 236 is shown to be mechanically coupled to the DISG input shaft 237.

[0021] The DISG 240 can be operated to provide torque for the powertrain 200 or to convert powertrain torque into electrical energy to be stored in an electrical energy storage device 275. The DISG 240 has a higher output torque capacity than the starter 96, which is located in Fig. Figure 1 shows the DISG 240. Furthermore, the DISG 240 directly drives the drivetrain 200 or is directly driven by the drivetrain 200. There are no belts, gears, or chains for coupling the DISG 240 to the drivetrain 200. Instead, the DISG 240 rotates at the same speed as the drivetrain 200. The electrical energy storage device 275 (e.g., a high-voltage battery or power source) can be a battery, a capacitor, or an inductor. The downstream side of the DISG 240 is mechanically coupled to the impeller 285 of the torque converter 206 via a shaft 241. The upstream side of the DISG 240 is mechanically coupled to the disconnect clutch 236.

[0022] The torque converter 206 includes a turbine 286 for delivering torque to an input shaft 270. The input shaft 270 couples the torque converter 206 to an automatic transmission 208. The torque converter 206 also includes a torque converter bypass lock-up clutch 212 (TCC). When the TCC is locked, the torque is transmitted directly from the impeller 285 to the turbine 286. The TCC is electrically operated by the control unit 12. Alternatively, the TCC can be locked hydraulically. In this example, the torque converter can be considered a component of the transmission.

[0023] When the torque converter locking clutch 212 is fully disengaged, the torque converter 206 transmits engine torque to the automatic transmission 208 via fluid transfer between the torque converter turbine 286 and the torque converter pump impeller 285, thus enabling torque multiplication. Conversely, when the torque converter locking clutch 212 is fully engaged, the engine torque is transmitted directly to an input shaft (not shown) of the transmission 208 via the torque converter clutch. Alternatively, the torque converter locking clutch 212 can be partially engaged to allow adjustment of the amount of torque transmitted directly to the transmission.The control unit 12 can be configured to adjust the amount of torque transmitted by the torque converter 212 by adjusting the torque converter locking clutch in response to different power machine operating conditions or based on a driver-based power machine operating requirement.

[0024] The automatic transmission 208 comprises gear clutches (e.g., gears 1 to 6) 211 and a forward clutch 210. The gear clutches 211 (e.g., 1 to 10) and the forward clutch 210 can be selectively engaged to propel a vehicle. The torque output from the automatic transmission 208 can, in turn, be transmitted to wheels 216 to propel the vehicle via an output shaft 260. Specifically, the automatic transmission 208 can transmit an input drive torque at the input shaft 270 in response to a vehicle driving condition before transmitting an output drive torque to the wheels 216.

[0025] Furthermore, a frictional force can be exerted on the wheels 216 by engaging the wheel brakes 218. In one example, the wheel brakes 218 can be engaged in response to the driver pressing their foot on a brake pedal (not shown). In other examples, the control unit 12 or a control unit connected to the control unit 12 can apply the engagement of the wheel brakes. Similarly, a frictional force on the wheels 216 can be reduced by disengaging the wheel brakes 218 in response to the driver releasing their foot from a brake pedal. Additionally, vehicle brakes can exert a frictional force on the wheels 216 via the control unit 12 as part of an automatic engine stop procedure.

[0026] The controller 12 can be configured to receive inputs from the power machine 10, as shown in Fig. 1 is shown in more detail, and controls the torque output of the engine and / or the operation of the torque converter, transmission, DISG, clutches, and / or brakes accordingly. For example, engine torque output can be controlled by adjusting a combination of ignition timing, fuel pulse width, fuel pulse timing, and / or air charge by controlling the throttle valve opening and / or valve timing, valve lift, and boost pressure for turbocharged or supercharged engines. In the case of a diesel engine, the control unit 12 can control the engine torque output by controlling a combination of fuel pulse width, fuel pulse timing, and air charge. In all cases, the engine control can be performed on a cylinder-by-cylinder basis to control the engine torque output.The control unit 12 can also control the torque output and the generation of electrical energy from the DISG by adjusting current flowing to and from the field and / or armature windings of the DISG, as is known in the field.

[0027] When idle-stop conditions are met, the control unit 12 can initiate engine shutdown by blocking fuel and ignition spark to the engine. However, in some examples, the engine may continue to rotate. Furthermore, to maintain a torsional force in the transmission, the control unit 12 can ground rotating elements of the transmission 208 to a housing 259 of the transmission and thereby to the vehicle frame. When engine restart conditions are met and / or the vehicle operator wishes to start the vehicle, the control unit 12 can reactivate the engine 10 by starting the engine 10 and resuming cylinder combustion.

[0028] Now with reference to Fig. Figure 3 shows an example of the operating sequence of a hybrid vehicle. The operating sequence of Fig. 3 can be achieved through the system of Fig. 1 and Fig. 2 will be provided, which is the procedure of Fig. 4 is executed, which is stored as instructions in a non-transitory memory. The vertical lines T1 to T5 represent respective points in time of interest during the execution.

[0029] The first graph from the top of Fig. Figure 3 is a graph of vehicle speed versus time. The y-axis represents vehicle speed, and the vehicle speed increases in the direction of the y-axis arrow. The x-axis represents time, and time increases from the left to the right side of the figure.

[0030] The second graph from the top of Fig. Figure 3 is a graph of active gear position versus time. The Y-axis represents an active gear position, and the active gear positions are shown along the Y-axis. The X-axis represents time, and time increases from the left to the right side of the figure.

[0031] The third graph from the top of Fig. Figure 3 is a graph of engine and DISG rotational speed versus time. The Y-axis represents the engine and DISG rotational speed, which increases in the direction of the Y-axis arrow. The X-axis represents time, and time increases from the left to the right side of the figure. The engine and DISG are coupled to each other via the powertrain disconnect clutch during this process.

[0032] The fourth graph from the top of Fig. Figure 3 is a graph of driver-demand torque versus time. The Y-axis represents driver-demand torque, and driver-demand torque increases in the direction of the Y-axis arrow. The X-axis represents time, and time increases from the left to the right side of the figure.

[0033] The fifth graph from the top of Fig. Figure 3 is a graph of the mass of air flowing through a power engine, or the mass of air flowing through the engine, versus time. The y-axis represents the mass of air flowing through the power engine, and this mass increases in the direction of the y-axis arrow. The x-axis represents time, and time increases from the left to the right side of the figure.

[0034] The sixth graph from the top of Fig. Figure 3 is a graph of DISG torque versus time. The Y-axis represents DISG torque, and the DISG torque increases in the direction of the Y-axis arrow. The X-axis represents time, and time increases from the left to the right side of the figure. The horizontal line 302 represents maximum DISG torque at DISG engine speeds below the point at which the DISG transitions from exhibiting a constant maximum torque output to exhibiting a constant maximum power output.

[0035] The seventh graph from the top of Fig. Figure 3 is a graph of machine torque versus time. The y-axis represents the machine torque, and the machine torque increases in the direction of the y-axis arrow. The x-axis represents time, and time increases from the left to the right side of the figure.

[0036] At time T0, after a cold start of the engine, the driver applies a driver request torque, and the vehicle speed begins to increase. The engine air mass, or the air flowing through the engine, is at a predetermined constant level. The DISG torque begins to increase in response to the driver request torque, and the engine torque begins to decrease, so that the DISG torque plus the engine torque fulfills the driver request torque at a torque converter impeller located downstream of the DISG. The engine speed increases because the DISG and engine are coupled, and because the combined DISG and engine torque increases in response to the driver request torque. The transmission is in first gear, and the vehicle speed begins to increase in response to the driver request torque.

[0037] At time T1, the transmission shifts into second gear. The transmission shifts in response to driver request torque and vehicle speed. Vehicle speed continues to increase, and engine speed and DISG speed decrease in response to the shift to a higher gear. Driver request torque gradually decreases in response to driver accelerator pedal input, and engine air mass remains constant even as engine speed decreases. Engine air mass can be kept constant at reduced engine speed by opening the engine throttle and / or advancing the intake valve timing. Opening the engine throttle and / or advancing the intake valve timing increases engine torque. DISG torque decreases in response to the increase in engine torque.

[0038] Between times T1 and T2, the engine's throttle valve closes (not shown) to maintain a constant engine airflow as engine speed and DISG speed increase. Closing the engine's throttle valve reduces the intake manifold pressure, causing the engine cylinders to produce less torque for each combustion event. Consequently, engine torque decreases in response to increasing engine speed, and a constant engine airflow is maintained.

[0039] At time T2, the transmission shifts from second to third gear in response to vehicle speed and driver request torque. The engine and DISG speeds decrease in response to the transmission engaging third gear. The engine air mass remains constant, and the engine torque increases in response to the decrease in engine speed to maintain the constant engine air mass. Engine torque is increased by opening the engine throttle valve or advancing the intake valve timing. DISG torque decreases in response to the increase in engine torque. The engine torque plus the DISG torque provides the desired driver request torque at the vehicle's torque converter pump wheel.

[0040] At time T3, the vehicle speed has reached a higher level, and the driver reduces the driver request torque by partially releasing the accelerator pedal. The engine torque increases to maintain engine airflow, and the DISG torque is reduced in response to the decreased driver request torque and the increased engine torque. The engine speed and DISG speed are reduced in response to the decreased driver request torque. The transmission remains in third gear, and the vehicle speed begins to decrease.

[0041] Between points T3 and T4, the driver request torque remains low, and the engine speed and DISG speed decrease in response to this low torque. The engine torque increases slightly to maintain the engine air volume, and the DISG torque decreases in response to this increase. The vehicle speed continues to decelerate.

[0042] At time T4, the driver increases the driver-request torque by pressing the accelerator pedal. The transmission remains in third gear, and the engine and DISG speeds begin to increase in response to the combined DISG and engine torque to provide the driver-request torque. The engine torque decreases as the engine speed increases to maintain constant engine airflow. The DISG torque increases as the driver-request torque increases and the engine torque decreases.

[0043] At time T5, the DISG torque reaches its torque limit of 302. This torque limit of 302 represents the maximum engine torque at the current DISG speed. The maximum DISG torque is a function of the DISG speed. The DISG torque is maintained at its maximum level, and the engine torque is increased so that the DISG torque plus the engine torque provides the driver-requested torque at the vehicle's torque converter pump wheel. The engine airflow is increased to further enhance the engine torque after the DISG reaches its maximum torque. Therefore, when the DISG is providing its maximum torque and additional torque is needed to meet the driver-requested torque, the engine airflow can be increased to meet the driver-requested torque.In this way, the engine airflow can be kept at a constant flow until the driver request torque exceeds the maximum DISG torque plus the engine torque when the engine is operated at the predetermined constant air mass.

[0044] Now with reference to Fig. Figure 4 describes a method for operating the powertrain of a hybrid vehicle. The method of Fig. 4 can be in the system of Fig. 1 and Fig. 2. The instructions may be executable and stored in non-transitory memory. Furthermore, the procedure may consist of Fig. 4. Provide the operational process that will take place in Fig. 3 is shown.

[0045] In procedure 402, the procedure assesses whether the engine is cold-started. Alternatively or additionally, procedure 400 can assess whether the engine is operating under predetermined conditions after a cold start, or whether the engine is operating under predetermined conditions after a warm start. The predetermined conditions after a cold and / or warm start can be that a catalyst temperature is lower than a first threshold temperature, and / or that an engine temperature is lower than a second threshold temperature. The engine is considered to be cold-started if the temperature of the engine and / or an exhaust component is lower than a threshold temperature (e.g., 20 °C) before the engine has been running for a predetermined period of time or before the engine has reached a threshold temperature.If procedure 400 determines that the engine is cold-started, or that the engine operates within predetermined conditions after a start, the answer is "Yes," and procedure 400 proceeds to 404. Otherwise, the answer is "No," and procedure 400 proceeds to 450.

[0046] At 450, Procedure 400 adjusts the engine air mass in response to driver demand torque, and the spark is adjusted to the knock limit or MBT ignition timing setting. For example, if driver demand torque increases, the engine air mass increases. If driver demand torque decreases, the engine air mass decreases. Additionally, the engine air-fuel ratio averages to a near-stoichiometric ratio. Procedure 400 terminates after the engine air-fuel ratio is adjusted.

[0047] In procedure 404, method 400 determines the engine speed. In one example, the engine speed is determined by measuring the time between engine positions using an engine position sensor. Furthermore, procedure 404 determines a driver request torque. In one example, the driver request torque can be based on an accelerator pedal position and a vehicle speed. Specifically, the vehicle speed and accelerator pedal position are used to index a table containing empirically determined driver request torques. The table outputs the driver request torque based on the accelerator pedal position and the vehicle speed. After determining the engine speed, procedure 400 proceeds to 406.

[0048] In procedure 400, method 406 determines the desired engine air mass, or the desired quantity of air to flow through the engine. In one example, the desired engine air mass is determined empirically and stored in a table or function indexed based on engine temperature and / or catalyst temperature. Additionally, the table or function may be indexed by time since the engine stopped. The table may contain desired engine air mass quantities that will allow a catalyst in the engine exhaust system to reach a desired temperature within a threshold time period. The desired engine air mass may be a substantially constant value (e.g.,with a variation of less than 10% from the time the engine speed reaches a threshold speed after an engine stop, until a catalyst reaches a desired temperature or until a driver request exceeds a threshold torque, including the time in between. Furthermore, in some examples, the substantially constant air mass may be based on an engine temperature or catalyst temperature during engine start-up. For example, the engine air mass may be a larger value for lower catalyst and engine temperatures, although the engine air mass remains constant from the time the engine reaches a threshold speed after an engine stop until predetermined conditions are met (e.g., the catalyst or engine reaches a threshold temperature).For example, if the engine temperature reaches 20°C during a first start, the engine airflow may be X kg / sec. However, if the engine temperature is 15°C during a second start, the engine airflow may be Y kg / sec, where Y is greater than X. The respective air masses X and Y can flow through the engine from the moment the engine speed reaches a threshold speed after an engine stop, until a catalyst reaches a desired temperature, or until a driver request exceeds a threshold torque. The desired engine air mass is provided by the table, and procedure 400 proceeds to 408.

[0049] In procedure 408, the procedure determines a desired ignition timing advance from minimum best torque (MBT) to retarded. In one example, the ignition timing advance from MBT to retarded is determined empirically and stored in a table or function, which may be indexed based on time since engine strobe and / or engine or catalyst temperature. The table or function outputs an ignition timing advance to retarded, and procedure 400 proceeds to 410. In one example, the ignition timing advance from the MBT setting to retarded may be substantially constant (e.g., changing by a crankshaft angle of less than 5 degrees) from the time of an engine stop until a catalyst reaches a desired temperature or until a driver request exceeds a threshold torque.

[0050] In 410, procedure 400 determines a desired engine torque to provide the desired engine air mass determined in 406. In an example, the desired engine airflow determined in 406 is multiplied by a fuel-air ratio to determine a fuel flow rate. The fuel flow rate can be used to index a table or function that outputs engine torque based on fuel flow rate and engine speed. The table or function outputs empirically determined engine torque values ​​that correspond to the engine torque at the current engine speed when the engine fuel flow is based on the desired airflow and fuel-air ratio. After determining the desired engine torque, procedure 400 proceeds to 412.

[0051] In case 412, procedure 400 determines the desired DISG or engine torque. In one example, the desired engine torque is determined by the following equation: TMOT=TDD−TDES_ENG where T MOT the desired engine torque is, T DD the driver request torque, and where T DES_ENG The desired engine torque is determined in step 410. After determining the desired engine torque, step 400 continues to step 414.

[0052] In case 414, procedure 400 determines whether the engine torque (e.g. T) MOT ) lower than the maximum engine torque (e.g. T) MOT_MAX ). If this is the case, the answer is "Yes," and procedure 400 proceeds to 416. Otherwise, the answer is "No," and procedure 400 proceeds to 418.

[0053] In the 416, procedure 400 determines the motor and engine torque commands. Specifically, the motor torque command T MOT_CMD= T MOT , or the engine torque command is the engine torque determined at 412. Specifically, the engine torque command T ENG_CMD = T DES_ENG , or the engine torque command is the engine torque determined at 410. Procedure 400 ends after the engine and motor commands have been determined.

[0054] In the case of 416, method 400 also ensures that the engine operates with a substantially constant air mass (e.g., an air mass that changes by less than 10%) when a transmission shifts gears. Furthermore, method 400 can cause a transmission to shift up from a lower gear to a higher gear in response to an engine speed that falls within a threshold speed at which the engine transitions from providing constant maximum torque to providing constant maximum power. By shifting up, the maximum DISG torque can be maintained at a higher value than if the DISG engine speed were to continue increasing. Consequently, the engine can be maintained with a constant air mass flowing through it, even as the engine speed increases.Accordingly, the 400 method can limit the DISG speed to a speed lower than the speed at which the DISG switches from providing a constant maximum torque to providing a constant maximum power in order to provide a greater maximum DISG torque.

[0055] Under conditions where the engine torque is greater than the driver request torque, the DISG can switch from a motor mode (e.g. providing positive torque to the drivetrain) to a generator mode (e.g. providing negative torque to the drivetrain) while the engine operates at a substantially constant air mass.

[0056] In 418, procedure 400 determines the motor and engine torque commands. Specifically, the motor torque command T MOT_CMD = T MOTMAX, or the engine torque command is the engine torque at the current engine speed. The power machine torque command is T ENG_CMD = T DD - T MOT_MAXThe engine torque command, or the driver request torque as specified at 404, is less the maximum engine torque at the current engine speed. Engine torque is adjusted by modifying the throttle position, intake valve closing timing, and / or fuel injection. Engine torque is adjusted by modifying the amount of current supplied to the engine. Furthermore, if the engine torque command is negative, the engine operates as a generator to absorb engine torque.Therefore, in procedure 418, the engine torque command increases with the driver request torque such that the engine airflow, in response to a driver request torque greater than the maximum engine torque, increases while the engine operates at a substantially constant air volume, and a maximum DISG torque at a current DISG speed increases from the substantially constant air volume. Procedure 400 ends after determining the engine and motor commands.

[0057] Engine torque can be adjusted by modifying the amount of injected fuel and the engine throttle position or intake valve closing time. For example, if the desired engine torque is adjusted to provide the desired engine air mass at varying engine speeds, the throttle or intake valve closing time can be adjusted to provide a desired intake manifold pressure that corresponds to the desired engine air volume flow at the current engine speed. Specifically, the engine intake manifold pressure to provide the desired engine air mass can be adjusted by modifying the engine throttle or intake valve closing time based on the following speed / density equation: P=R⋅T⋅Me⋅2ην⋅Ne where Me is the desired engine airflow, R is a gas constant, T is the air temperature, N e The engine speed is P, the manifold pressure is P, and η is η. v The volumetric efficiency of the engine is the relevant factor. Intake manifold pressure can be used for closed-loop control. For example, if the intake manifold pressure, based on feedback from a pressure sensor, is higher than desired, the throttle valve can be closed further.

[0058] The procedure of Fig. Section 4 therefore provides a method comprising: operating a power engine at a substantially constant air mass and ignition timing in response to a catalyst temperature below a threshold; changing a power engine torque as the power engine speed changes while simultaneously operating the power engine at the substantially constant air mass; and providing a driver request torque via a power engine torque and an engine torque while simultaneously operating the power engine at the substantially constant air mass. The method comprises delaying the ignition timing from the minimum advance for best power engine torque. The method comprises adjusting the power engine torque by changing the position of a throttle valve.

[0059] In some examples, the method involves further adjusting the engine torque by modifying the amount of fuel injected into the engine. The method also involves adjusting the engine torque by modifying the position of an intake cam or the timing of an intake valve. The method involves operating the engine at a substantially constant air mass when a transmission changes gears. The method also involves modifying the substantially constant air mass in response to engine or catalyst temperature during engine start-up.The procedure further includes upshifting a gear in response to the fact that an engine speed is within a threshold speed at which the engine transitions from providing constant maximum torque to providing constant maximum power.

[0060] The procedure of Fig. 4 further provides for: changing a power engine torque as the power engine speed changes while simultaneously operating a power engine at a substantially constant air mass in response to a temperature lower than a threshold, and a driver request torque lower than a maximum power engine torque plus a maximum torque of a starter / generator integrated into the powertrain (DISG), wherein the maximum power engine torque is generated while the power engine is operating at the substantially constant air mass, and wherein the maximum (DISG) torque is at a current DISG speed; and providing a driver request torque via a power engine torque and a DISG torque while simultaneously operating the power engine at the substantially constant air mass.

[0061] In some examples, the method involves the engine operating at a substantially constant ignition timing setting while operating at a substantially constant air mass. The method also involves the temperature being either a catalyst temperature or an engine temperature. Furthermore, the method involves increasing the engine air volume from the substantially constant air volume in response to a driver request torque greater than the maximum engine torque while the engine is operating at the substantially constant air volume, and achieving maximum DISG torque at a given DISG engine speed.The method further comprises upshifting a transmission gear in response to a DISG speed being within a threshold speed at which the DISG transitions from constant maximum torque to constant maximum power. The method comprises adjusting the substantially constant air mass in response to engine start-up temperature. Method 400 comprises limiting the DISG speed to a speed lower than the speed at which the DISG transitions from providing constant maximum torque to providing constant maximum power.

[0062] In some examples, the procedure of Fig. 4. A method comprising: changing an engine torque as the engine speed changes while operating the engine at a substantially constant air mass; switching a drivetrain-integrated starter / generator (DISG) from an engine mode to a generator mode in response to an engine torque exceeding a driver request torque while the engine is operating at a substantially constant air mass; and providing a driver request torque via an engine torque and an engine torque while operating the engine at a substantially constant air mass.The method further comprises increasing the engine air volume from the substantially constant air volume in response to a driver request torque greater than the maximum engine torque while the engine is operating at the substantially constant air volume, and a maximum DISG torque at a given DISG speed. The method further comprises upshifting a transmission gear in response to a DISG speed being within a threshold speed at which the DISG transitions from constant maximum torque to constant maximum power. The method further comprises limiting the DISG speed to a speed lower than the speed at which the DISG transitions from providing constant maximum torque to providing constant maximum power.The method involves operating the engine at a substantially constant ignition timing setting when the engine is operated at a substantially constant air mass.

[0063] As an average expert can see, the in Fig.The procedures described in section 4 represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, and the like. Accordingly, various illustrated steps or functions can be executed in the illustrated order, in parallel, or, in some cases, omitted. Likewise, the processing order is not strictly necessary to achieve the tasks, features, and benefits described here, but serves to simplify illustration and description. Although not explicitly stated, it is obvious to the average person that one or more of the illustrated steps or functions can be performed repeatedly, depending on the specific strategy used.Furthermore, the described actions, operations, procedures and / or functions can graphically represent code that is to be programmed into a non-transitory memory of the computer-readable storage medium in the power engine control system.

[0064] This concludes the description. Experts will likely think of many changes and modifications upon reading it, without deviating from the essence and scope of the description. For example, I3, I4, I5, V6, V8, V10, and V12 engines that operate on natural gas, gasoline, diesel, or alternative fuel configurations could benefit from this description.

Claims

[1] Procedure, encompassing: Operating a power engine (10) at a substantially constant air mass flow and ignition timing adjustment in response to a catalyst temperature below a threshold; Changing a power machine torque (T DES_ENG ) with changing engine speed while simultaneously operating the engine (10) at a substantially constant air mass flow; and Providing a driver request torque (T DD ) via a power machine torque (T DES_ENG ) and engine torque (T MOT ) while simultaneously operating the power engine (10) at the substantially constant air mass flow. [2] Method according to claim 1, wherein the ignition timing adjustment is delayed by a minimum advance for optimal engine torque. [3] Method according to claim 1 or 2, wherein the engine torque (T DES_ENG) is adjusted by adjusting the position of a throttle valve (62). [4] Method according to claim 3, wherein the engine torque (T DES_ENG ) is further adjusted by adjusting the amount of fuel injected into the engine (10). [5] Method according to any one of claims 2 to 4, wherein the engine torque (T DES_ENG ) by adjusting the position of an inlet cam (51) or the timing of an inlet valve (52). [6] Method according to any one of claims 1 to 5, wherein the power engine (10) is operated at the substantially constant air mass flow when a transmission changes gears. [7] Method according to any one of claims 1 to 6, wherein the substantially constant air mass flow is based on an engine or catalyst temperature during an engine start. [8] Method according to any one of claims 1 to 7, further comprising upshifting a gear in response to the fact that the engine speed is within a threshold speed at which the engine transitions from providing a constant maximum torque to providing a constant maximum power. [9] Procedures, comprehensive: Changing a power machine torque (T DES_ENG ) when the engine speed changes while simultaneously operating an engine (10) at a substantially constant air mass flow in response to a temperature below a threshold and a driver request torque (T DD), which is lower than a maximum engine torque plus a maximum torque of a starter / generator (DISG) integrated into the powertrain (240), wherein the maximum engine torque is generated while the engine (10) operates at the substantially constant air mass flow, and wherein the maximum DISG torque is at a current DISG speed; and Providing a driver request torque (T DD ) via a power machine torque (T DES_ENG ) and DISG torque when operating the engine (10) simultaneously at the substantially constant air mass flow. [10] Method according to claim 9, wherein the engine (10) is operated at a substantially constant ignition timing setting when the engine (10) is operated at the substantially constant air mass flow. [11] Method according to claim 9 or 10, wherein the temperature is a catalyst temperature or an engine temperature. [12] Method according to any one of claims 9 to 11, further comprising increasing the engine air volume from the substantially constant air volume in response to a driver request torque (T DD ), which is greater than the maximum engine torque, while the engine (10) operates at the substantially constant air volume and a maximum DISG torque at a current DISG speed. [13] Method according to any one of claims 9 to 12, further comprising upshifting a transmission gear in response to the fact that a speed of the DISG (240) is within a threshold speed of a speed at which the DISG (240) transitions from a constant maximum torque to a constant maximum power. [14] Method according to any one of claims 9 to 13, wherein the substantially constant air mass flow is based on a temperature at engine start. [15] Method according to any one of claims 9 to 14, further comprising limiting the DISG rotational speed to a rotational speed which is lower than a rotational speed at which the DISG (240) transitions from providing a constant maximum torque to providing a constant maximum power. [16] Procedure, comprehensive: Changing a power machine torque (T DES_ENG ) with changing engine speed while simultaneously operating the engine (10) with a substantially constant air mass flow; Switching a drivetrain integrated starter / generator (DISG) (240) from a motor mode to a generator mode in response to a power engine torque (T DES_ENG ) a driver request torque (T DD) exceeds, while the engine (10) operates at the substantially constant air mass flow; and Providing a driver request torque (T DD ) via a power machine torque (T DES_ENG ) and engine torque (T MOT ) while simultaneously operating the power engine (10) at the substantially constant air mass flow. [17] Method according to claim 16, further comprising increasing the engine air volume from the substantially constant air volume in response to a driver request torque (T DD ), which is greater than the maximum engine torque, while the engine (10) operates at the substantially constant air volume and a maximum DISG torque at a current DISG speed. [18] Method according to claim 16 or 17, further comprising upshifting a transmission gear in response to the fact that a speed of the DISG (240) is within a threshold speed of a speed at which the DISG (240) transitions from a constant maximum torque to a constant maximum power. [19] Method according to any one of claims 16 to 18, further comprising limiting the DISG rotational speed to a rotational speed which is lower than a rotational speed at which the DISG (240) transitions from providing a constant maximum torque to providing a constant maximum power. [20] Method according to any one of claims 16 to 19, wherein the engine (10) is operated at a substantially constant ignition timing setting when the engine (10) is operated at the substantially constant air mass flow.

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