Method and system for operating a hybrid vehicle in cruise control mode

Abstract

Procedure, comprehensive: During a speed control mode, delaying a change in the drive sources that provide torque to a power transmission or absorb torque from the power transmission in response to a time interval since a change in a desired vehicle speed.

Description

Area

[0001] This description relates to methods and a system for reducing mode-change activity in a hybrid vehicle. The methods may be particularly useful for hybrid vehicles that include a power transmission disconnect clutch, an engine, and a starter / generator integrated into the power transmission (drivetrain). Background and Summary

[0002] A hybrid vehicle can incorporate a power transmission that operates in a variety of modes to improve power transmission efficiency. For example, the hybrid power transmission might include an engine, a power transmission disconnect clutch, and a driveline integrated starter / generator (DISG). The engine and DISG can selectively provide torque to the hybrid power transmission. In one mode, the engine can be decoupled from the DISG, allowing the DISG to propel the hybrid vehicle without expending energy to turn the engine when the engine is not burning an air-fuel mixture and supplying torque to the power transmission (DISG-only mode). In another mode, the engine can provide torque to propel the vehicle when the DISG is not supplying torque to the power transmission or is absorbing torque from the power transmission (engine-only mode).In yet another mode, both the engine and the DISG can provide torque to propel the vehicle (DISG / engine mode). Accordingly, the hybrid power transmission can operate in a variety of modes based on vehicle operating conditions.

[0003] The same power transmission modes can be made available when the hybrid vehicle is operating in cruise control mode. The vehicle can enter cruise control mode when requested by a driver or controller. The driver or controller selects a desired vehicle speed, and the torque delivered to the vehicle's wheels is adjusted to maintain that speed within a threshold of the desired speed. The actual vehicle speed, as determined from the output of a wheel speed sensor or power transmission speed sensor, can be used as feedback for controlling the vehicle speed. The actual vehicle speed can be subtracted from the desired vehicle speed to determine a vehicle speed error.The vehicle speed error can be multiplied by a gain or control transfer function to provide an adjustment of the power transmission torque. This adjusted power transmission torque can be output to the engine and / or DISG, which supplies torque to the power transmission, so that the vehicle speed approaches the desired speed.

[0004] The engine and / or DISG torque can be continuously adjusted to maintain the desired vehicle speed in cruise control mode, as the power transmission torque required to maintain the desired speed can change due to varying road conditions, including gradients. Additionally, a driver or control unit can adjust the desired vehicle speed depending on vehicle and / or road conditions. For example, a driver might reduce the desired vehicle speed in response to entering a roadworks zone while the vehicle is in cruise control mode. Similarly, the driver might increase the desired vehicle speed in response to exiting the roadworks zone.Changing the desired vehicle speed can initiate a change in the torque requested by the engine and / or DISG, causing the vehicle to approach the new desired speed. However, changing the requested transmission torque can also initiate an engine stop or restart (e.g., a change in the transmission operating mode), which may be undesirable because the engine might restart shortly after being stopped to propel the vehicle at the new desired speed. Furthermore, the transmission disconnect clutch can open and then close shortly thereafter to change the transmission operating modes and provide the desired new vehicle speed. Frequent changes in transmission modes (e.g.,Changes in the power transmission mode (e.g., during operation) can reduce the durability of the power transmission and disturb the vehicle's occupants. For these reasons, it may be desirable to provide a procedure and system that reduces changes in the power transmission mode during a vehicle's cruise control mode.

[0005] A control unit for a vehicle is known from US 2014 / 0 288 744 A1.

[0006] The inventors here have recognized the aforementioned disadvantages and have developed a method that involves: during a speed control mode, delaying a change in the drive sources that provide torque to a power transmission or absorb torque from the power transmission, in response to a time interval since a change in a desired vehicle speed.

[0007] By delaying a change in the power transmission mode in response to a time interval since a change in the desired vehicle speed was initiated, it may be possible to provide the technical result of avoiding power transmission mode change activity, which can be present in vehicle systems that use torque demand as a primary variable for power transmission mode changes. For example, a power transmission mode change can be delayed by a predetermined time interval since a change in the desired vehicle speed. As a result, the power transmission would not immediately switch operating modes, even if there were a large change in the desired power transmission torque, wheel torque, or transmission input shaft torque.As a result, the power transmission would switch between modes less frequently when the vehicle is operating in a cruise control mode.

[0008] The present description can provide several advantages. In particular, the approach can reduce the possibility of driver distraction due to frequent changes in the power transmission mode. Additionally, the approach can reduce the potential for deterioration of power transmission components. Furthermore, the approach can improve the vehicle's fuel economy by reducing unnecessary changes in the power transmission mode. The described advantages, along with other benefits and features of this description, will be readily apparent from the following "Detailed Description," whether considered on its own or in conjunction with the accompanying drawings.

[0009] It is understood that the above summary is provided to introduce, in simplified form, a selection of concepts that are further described in the detailed description. It is not intended to identify key or essential features of the claimed subject matter, the scope of which is clearly defined by the claims following the detailed description. Furthermore, the claimed subject matter is not limited to implementations that resolve disadvantages identified above or in any part of this disclosure. Brief description of the drawings

[0010] The advantages described herein will be more fully understood by reading an example of an embodiment referred to herein as the "Detailed Description", either on its own or with reference to the drawings, of which: Fig. 1 shows a schematic diagram of an engine; Fig. 2 shows an exemplary configuration of a vehicle power transmission; Fig. Figure 3 shows a block diagram of an example vehicle speed control system; Fig. 4 shows an exemplary hybrid vehicle operating sequence; and the Fig. Sections 5A to 5C demonstrate an exemplary procedure for operating a hybrid vehicle power transmission. Detailed description

[0011] This description concerns the operation of a hybrid vehicle in cruise control mode. The hybrid vehicle may contain an engine, as shown in Fig. 1 shown. The motor can be included in a power transmission, as shown in Fig. 2 shown. Furthermore, the hybrid vehicle may include a vehicle speed control or regulation system, as shown in Fig. 3 shown. The power transmission can be operated in speed control mode, as shown in Fig. Figure 4 illustrates how to reduce power transmission mode change activity. In particular, the actual total number of power transmission mode changes during a transition from a first vehicle speed to a second vehicle speed while the hybrid vehicle is in cruise control mode can be reduced according to the procedure shown. Fig. 5A to 5C will be reduced.

[0012] Referring to Fig. 1, an internal combustion engine 10, comprising a plurality of cylinders, one of which is in Fig. The engine 10, as shown in Figure 1, is controlled by an electronic engine control unit 12. The engine 10 contains a combustion chamber 30 and cylinder walls 32 with a piston 36 positioned therein and connected to a crankshaft 40. A flywheel 97 and a ring gear 99 are coupled to the crankshaft 40. A starter 96 (e.g., a low-voltage electric machine (operated at less than 30 volts)) contains a pinion shaft 98 and a pinion 95. The pinion shaft 98 can selectively advance the pinion 95 to engage 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 resting state when it is not engaged with the engine crankshaft.The combustion chamber 30 is shown communicating with the intake manifold 44 and exhaust manifold 48 via a respective intake valve 52 and exhaust valve 54. Each intake and exhaust valve can be operated 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.

[0013] The fuel injector 66 is shown positioned to inject fuel directly into cylinder 30, a process known to those skilled in the field as direct injection. Alternatively, fuel can be injected into an intake port, a process known to those skilled in the field as port injection. The fuel injector 66 supplies liquid fuel from the controller 12 in proportion to the pulse width. Fuel is supplied to the fuel injector 66 by a fuel system (not shown) comprising a fuel tank, a fuel pump, and a fuel distribution pipe (not shown).

[0014] Furthermore, the intake manifold 44 is shown communicating with the turbocharger compressor 162. The shaft 161 mechanically couples the turbocharger turbine 164 to the turbocharger compressor 162. The optional electronic throttle valve 62 adjusts the position of the throttle plate 64 to control the 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, so that the throttle valve 62 is a port throttle valve.

[0015] The distributorless ignition system 88 provides a spark to the combustion chamber 30 via the spark plug 92 in response to the control unit 12. The universal exhaust gas oxygen sensor (UEGO sensor) 126 is shown coupled to the exhaust manifold 48 upstream of the catalytic converter 70. Alternatively, a two-stage exhaust gas oxygen sensor can be used instead of the UEGO sensor 126.

[0016] In one example, the converter 70 can contain multiple catalyst honeycomb structures. In another example, multiple emission control devices, each with multiple honeycomb structures, can be used. The converter 70 can also be a three-way catalyst.

[0017] Control 12 is in Fig. 1 is represented as a conventional microcomputer with a microprocessor unit 102, input / output ports 104, a read-only memory 106 (e.g. non-volatile memory), a random access memory 108, a retained memory 110 and a conventional data bus.The control unit 12 is configured to receive, in addition to the signals discussed above, various signals from sensors coupled to the engine 10, including: engine coolant temperature (ECT) from temperature sensor 112, coupled to the cooling jacket 114; a position sensor 134, coupled to an accelerator pedal 130 to detect the force exerted by the foot 132; a position sensor 154, coupled to the brake pedal 150 to detect the force exerted by the foot 152; a manifold pressure (MAP) measurement from pressure sensor 122, coupled to the intake manifold 44; an engine position sensor from a Hall effect sensor 118, which detects the position of the crankshaft 40; and a measurement of the mass of air entering the engine from sensor 120. and a measurement from the throttle position sensor 58. The barometric pressure can also be recorded for processing by the control unit 12 (sensor not shown).In a preferred aspect of the present description, the engine position sensor 118 generates a predetermined number of evenly spaced pulses at each revolution of the crankshaft, from which the engine speed (rpm) can be determined.

[0018] In some examples, the engine in a hybrid vehicle can be coupled to an electric motor / battery system, as in Fig. Figure 2 is shown. Furthermore, other engine configurations can be used in some examples, for example a diesel engine.

[0019] During operation, each cylinder in the engine 10 typically completes a four-stroke cycle: the cycle includes the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke. During the intake stroke, the exhaust valve 54 generally closes and the intake valve 52 opens. Air is drawn 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 in the combustion chamber 30. The position in 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 experts in the field as the bottom dead center (BDC).

[0020] 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 at the end of its stroke and closest to the cylinder head (e.g., when the combustion chamber 30 has its smallest volume) is typically referred to by experts in the field as the 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 an ignition device such as the spark plug 92, resulting in combustion.

[0021] During the expansion stroke, the expanding gases push the piston 36 back towards the BDC. The crankshaft 40 converts the piston motion into a rotational torque of the rotating shaft. Finally, during the exhaust stroke, the exhaust valve 54 opens to release the burnt air-fuel mixture into the exhaust manifold 48, and the piston returns to the TDC. It should be noted that the above is presented only as an example and that valve timing for opening and / or closing the intake and exhaust valves can vary to provide positive or negative valve overlap, late intake valve closing, or various other examples.

[0022] Fig. Figure 2 shows a block diagram of a vehicle 225, which includes a power transmission 200. The power transmission of Fig. 2 contains the one in Fig. Motor 10 is shown in Figure 1. The power transmission 200 can be driven by motor 10. Motor 10 can be equipped with a [missing information - likely a specific component or component]. Fig. The engine can be started either via the engine starting system shown in Figure 1 or via the starter / generator (DISG) 240 integrated into the power transmission. 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, an electric motor, and / or a generator. Furthermore, the torque of the engine 10 can be adjusted via a torque actuator 204, such as a fuel injector, throttle valve, etc.

[0023] An output torque of the engine can be transmitted to the input side of the power transmission disconnect clutch 236 via an optional dual-mass flywheel 215. Accordingly, the engine is directly coupled to the power transmission disconnect clutch 236 without any intermediate gears or devices. The dual-mass flywheel may contain masses and springs that act as a mechanical damper. Therefore, the dual-mass flywheel can be described as a damping flywheel, in contrast to flywheels that do not contain springs and are not referred to as damping flywheels. Flywheels that do not contain springs may also be described as non-damping flywheels, although the flywheel's inertia may provide a small amount of damping to the power transmission.In some exemplary power transmission configurations, the dual-mass flywheel 215 may be omitted or have a reduced mass, which is made possible by capacity control of the power transmission clutch torque. The disconnect clutch 236 can be electrically or hydraulically actuated. The downstream side of the disconnect clutch 236 is shown as mechanically coupled to the DISG input shaft 237. Accordingly, the disconnect clutch 236 is directly coupled to the DISG 240 without any intermediate gears or devices.

[0024] The DISG 240 can be operated to provide torque to the power transmission 200 or to convert torque from the power transmission into electrical energy, which is to be stored in the electrical energy storage device 275. The DISG 240 has a higher output torque capacity than the one in Fig. The starter 96 is shown. Furthermore, the DISG 240 directly drives the power transmission 200 or is directly driven by the power transmission 200. There are no belts, gears, or chains to couple the DISG 240 to the power transmission 200. Rather, the DISG 240 rotates at the same rate as the power transmission 200. The electrical energy storage device 275 (e.g., 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 directly to the impeller 285 of the torque converter 206 via the shaft 241. The upstream side of the DISG 240 is mechanically coupled to the disconnect clutch 236.

[0025] The torque converter 206 includes a turbine 286 to output torque to the input shaft 270. The input shaft 270 mechanically couples the torque converter 206 to the automatic transmission 208. The torque converter 206 also includes a torque converter bypass lock-up clutch (TCC) 212. Torque is transmitted directly from the impeller 285 to the turbine 286 when the TCC is locked. The TCC is electrically operated by the controller 12. Alternatively, the TCC can be hydraulically locked. In this example, the torque converter can be considered a component of the transmission.

[0026] When the torque converter lock-up 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 impeller 285, thus multiplying the torque. Conversely, when the torque converter lock-up clutch 212 is fully engaged, the engine's output torque is transmitted directly to an input shaft (not shown) of the transmission 208 via the torque converter clutch. Alternatively, the torque converter lock-up clutch 212 can be partially engaged, allowing 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 lock-up clutch in response to different engine operating conditions or based on a driver-based engine operating requirement.

[0027] The automatic transmission 208 includes gear clutches (e.g., gears 1-6) 211 and a forward clutch 210. The gear clutches 211 (e.g., 1-10) and the forward clutch 210 can be selectively engaged to propel a vehicle. Torque output from the automatic transmission 208 can, in turn, be transmitted to the wheels 216 to propel the vehicle via the output shaft 260. In particular, the automatic transmission 208 can transfer an input driving torque at the input shaft 270 in response to a driving condition of the vehicle before outputting a driving torque to the wheels 216.

[0028] Furthermore, a frictional force can be applied to the wheels 216 by actuating the wheel brakes 218. In one example, the wheel brakes 218 can be actuated in response to the driver pressing their foot on a brake pedal (not shown). In other examples, the controller 12 or a controller linked to the controller 12 can actuate the wheel brakes. Similarly, a frictional force on the wheels 216 can be reduced by reducing the wheel brakes 218 in response to the driver releasing their foot from a brake pedal. Additionally, the vehicle's brakes can apply a frictional force to the wheels 216 via the controller 12 as part of an automated engine shutdown procedure. The vehicle speed sensor 265 provides power transmission position or wheel position data for determining the vehicle speed.

[0029] The controller 12 can be configured to receive inputs from the motor 10, as detailed in Fig. 1 is shown, and accordingly, to control a torque output of the engine and / or the operation of the torque converter, the transmission, the DISG, the clutches, and / or the brakes. As an example, a torque output of the engine can be controlled by adjusting a combination of ignition timing, fuel pulse width, fuel pulse timing, and / or air charge, by controlling throttle opening and / or valve timing, valve lift, and boost pressure for turbocharged or supercharged engines. In the case of a diesel engine, the controller 12 can control the engine's torque output by controlling a combination of fuel pulse width, fuel pulse timing, and air charge. In all cases, engine control can be performed on a cylinder-by-cylinder basis to control the engine's torque output.The controller 12 can also control the torque output and the production of electrical energy from the DISG by adjusting the current flow to and from the field and / or armature windings of the DISG, as is known in the field.

[0030] When idle shutdown conditions are met, the control unit 12 can initiate engine shutdown by cutting off fuel and spark to the engine. In some examples, however, the engine may continue to rotate. Furthermore, to maintain a certain amount of torsion in the transmission, the control unit 12 can ground rotating elements of the transmission 208 to a housing 259 of the transmission and thus to the vehicle frame. When engine restart conditions are met and / or a vehicle operator wishes to start the vehicle, the control unit 12 can restart the engine 10 by rotating the engine 10 and resuming cylinder combustion.

[0031] Accordingly, the system of Fig. 1 and Fig. 2. A system for a hybrid vehicle comprising: an engine; a starter-generator integrated into the transmission (DISG); a transmission disconnect clutch mechanically coupled to the engine and the DISG; a transmission; and a control unit containing instructions for switching from a first transmission mode to a second transmission mode in response to an estimate of the time to change from a current vehicle speed to a new vehicle speed while the hybrid vehicle is operating in cruise control mode. The system includes the first mode being an engine-only mode and the second mode being a DISG-only mode. The system further includes additional instructions for closing the transmission disconnect clutch in response to the estimate of the time to change from the current vehicle speed to the new vehicle speed.

[0032] In some examples, the system also includes additional instructions to upshift the transmission in response to a DISG engine speed being higher than the DISG engine speed at which maximum DISG torque is available. The system also includes additional instructions to operate the engine in a deceleration fuel-saving mode in response to the time it takes to change from the current vehicle speed to the new vehicle speed. Furthermore, the system includes additional instructions to delay the transition from the first power transmission mode to the second power transmission mode in response to the time elapsed since a transition from a first desired vehicle speed to a second desired vehicle speed.

[0033] Now referring to Fig. Figure 3 shows a block diagram of an exemplary hybrid vehicle speed control system. The vehicle speed control or speed control mode system 300 receives a desired vehicle speed from a driver or controller. The desired vehicle speed is passed through a low-pass filter to smooth transitions between different desired vehicle speeds that may be requested at different times. The actual vehicle speed is subtracted from the filtered desired vehicle speed at the summing branch 304. An error value is output by the summing branch 304 and fed into the proportional, integral, and derivative (PID) controller 306. The error is multiplied by proportional, integral, and derivative gains. The resulting values ​​are summed and fed to the engine and DISG torque controller 308.

[0034] The engine and DISG torque controller 308 allocates a portion of the PID controller's output to controlling the engine torque and the remainder to controlling the DISG torque. The DISG and engine can operate together in an engine / DISG mode, in an engine-only mode where the engine is the sole torque source for power transmission, or in a DISG-only mode where the DISG is the sole torque source for power transmission. The engine and DISG can provide positive or negative torque to the power transmission. The power transmission disconnect clutch (DCC) is opened and closed by the power transmission disconnect clutch controller 310. For example, when the power transmission is in engine-only mode, the disconnect clutch is closed, allowing engine torque to be delivered to the transmission and vehicle wheels.If the power transmission is in DISG-only mode, the disconnect clutch remains open. When the engine and DISG are operating together (e.g., both supplying positive torque to the power transmission, or the engine supplying positive torque and the DISG absorbing torque, or both the engine and DISG supplying negative torque to the power transmission), the power transmission disconnect clutch is closed to mechanically couple the engine and DISG. The engine and DISG torque can result in the generation of a vehicle speed, which is fed back to the summing branch 304.

[0035] Now referring to Fig. Section 4 illustrates an exemplary operating sequence of a hybrid vehicle. The sequence of Fig. 4 can be achieved through the system of Fig. 1 and Fig. 2, which is the procedure stored as instructions in non-volatile memory of Fig. Execute steps 5A to 5C. The vertical lines at T1 to T9 represent times of particular interest during the process. Throughout the entire process of Fig. 4. The hybrid vehicle is operated in a closed-loop speed control mode, in which the vehicle speed is controlled to the desired vehicle speed.

[0036] The first graphic representation from above in Fig. Figure 4 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 left to right of the figure. The solid line 400 represents the actual vehicle speed. The dashed line 401 represents the desired vehicle speed. The actual vehicle speed and the desired vehicle speed are the same when only the solid line 400 is visible.

[0037] The second graphic representation from the top in Fig. Figure 4 is a graphical representation of the engine state against time. The Y-axis represents the engine state; the engine can be off when it is not burning an air-fuel mixture, and running when it is burning an air-fuel mixture. The engine is running when the curve is close to the Y-axis arrow. The engine is off when the curve is at a height close to the X-axis. The X-axis represents time, and time increases from left to right in the figure.

[0038] The third graphic representation from the top in Fig. Figure 4 is a graphical representation of the elapsed time since a change in the desired vehicle speed against time. The Y-axis represents the elapsed time since the change in the desired vehicle speed, and the elapsed time since a change in the desired vehicle speed increases in the direction of the Y-axis arrow. The elapsed time since a change in the desired vehicle speed is reset to zero when the new vehicle speed is reached. The X-axis represents time, and time increases from left to right of the figure. The horizontal line 402 represents a minimum time delay t. delay_min for some power transmission mode changes. The horizontal line 404 represents a predetermined power transmission mode change time delay t. delay2 for some mode changes of power transmission.

[0039] The fourth graphic representation from the top in Fig. Figure 4 represents the state of charge (SOC) of the battery against time. The Y-axis represents the SOC, which increases along the Y-axis. The X-axis represents time, and time increases from left to right of the figure. The battery's state of charge can range from zero to one hundred, where zero represents zero stored charge and one hundred represents a battery charged to its full nominal capacity. The horizontal line 410 represents a lower SOC limit. LIM , under which the engine is kept running or started.

[0040] The fifth graphic representation from the top in Fig. Figure 4 is a graphical representation of the operating state of the driveline disconnect clutch (DCC) against time. The Y-axis represents the DCC state, and the DCC is open when the curve is at a lower level near the X-axis. The DCC is closed when the curve is near the level of the Y-axis arrow. The X-axis represents time, and time increases from left to right in the figure.

[0041] The sixth graphic representation from the top in Fig. Figure 4 is a graphical representation of the gear ratio against time. The Y-axis represents the gear ratio, and the respective gear ratios are labeled along the Y-axis (e.g., P represents Park). A gear is engaged when the curve is at the gear level shown along the Y-axis. The X-axis represents time, and time increases from left to right in the figure.

[0042] At time T0, the hybrid vehicle is operating in a closed-loop speed control mode, where the vehicle speed is controlled to the desired vehicle speed of 401. The actual vehicle speed is 400, while the desired vehicle speed is 401, and the engine is burning air and fuel. The elapsed time since the change in the desired vehicle speed is zero, and the state of charge (SOC) is at a higher level. The DCC is closed, and the transmission is operating in third gear.

[0043] At time T1, the driver requests a change in vehicle speed from a higher to a lower speed, as indicated by curve 401. The engine continues to run, and the elapsed time since the requested change in vehicle speed increases. The state of charge (SOC) remains high, and the DCC remains closed. The transmission continues to operate in third gear.

[0044] At time T2, the elapsed time since the request to change the vehicle speed exceeds t. delay_min Furthermore, it is determined that the road load torque at the second vehicle speed (not shown) is smaller than the maximum DISG torque T. DISG_MAX The SOC is larger than the SOC MIN and the estimated time to change from the first vehicle speed (current vehicle speed) to the second vehicle speed (new vehicle speed) (Δtspd_chg) is greater than a predetermined time t 21_minhi (not shown). Therefore, the transmission shifts up a gear to reduce the DISG engine speed to a speed below the base DISG engine speed, a speed below which maximum DISG torque is available. Furthermore, the DCC (Dynamic Chassis Control) opens to allow the engine speed to deviate from the DISG engine speed. In this example, the engine speed changes to idle speed (not shown).

[0045] At time T3, the elapsed time since the request to change the vehicle speed exceeds t. delay2and all other conditions described at time T2 are met. Consequently, the engine is shut off at zero RPM by cutting off the spark and fuel supply. The vehicle speed decreases to the new desired vehicle speed because less torque is supplied to the power transmission by the engine and the DISG. The elapsed time since the request to change the vehicle speed is reset to zero when the vehicle speed reaches the new desired vehicle speed.

[0046] At time T4, the driver requests a change in vehicle speed from a lower to a higher speed, as indicated by curve 401. The DISG provides torque to the transmission (not shown), and the elapsed time since the requested change in vehicle speed increases. The state of charge (SOC) remains high, and the DCC remains open. The transmission continues to operate in fourth gear. The road load torque at the second or new vehicle speed (not shown) is less than the maximum wheel torque that can be provided by the DISG (not shown). Furthermore, the estimated time to change from the first or current vehicle speed to the new or second vehicle speed is determined solely by the DISG torque (Δt). spd_chg_DISG ) shorter than a threshold time (t up_max1 Therefore, the engine will not be started.

[0047] At time T5, the road load torque at the second or new vehicle speed (not shown) is less than the maximum wheel torque that can be provided by the DISG (not shown). Furthermore, the estimated time to change from the first or current vehicle speed to the new or second vehicle speed is determined solely by the DISG torque (Δt). spd_chg_DISG ) longer than a threshold time (t up_max1 However, the SOC is smaller than the SOC threshold. MIN 410. Therefore, the DCC is closed, the transmission is downshifted to a lower gear, and the engine is started. The engine revs up to the DISG speed and begins to transmit positive torque for power transmission.

[0048] At time T6, the driver requests a change in vehicle speed from a higher to a lower speed, as indicated by curve 401. The engine continues to run, and the elapsed time since the requested speed change increases. The state of charge (SOC) remains high, and the DCC remains closed. The transmission continues to operate in third gear.

[0049] At time T7, the elapsed time since the request to change the vehicle speed exceeds t. delay_min Furthermore, it is determined that the road load torque at the second vehicle speed (not shown) is smaller than the maximum DISG torque T. DISG_MAX The SOC is larger than the SOC MIN and the estimated time to change from the first vehicle speed (current vehicle speed) to the second vehicle speed (new vehicle speed) (Δtspd_chg ) is greater than a predetermined time t 21_minhi (not shown). As a result, the transmission shifts up a gear to reduce the DISG engine speed to a speed below the base DISG engine speed, a speed at which maximum DISG torque is available. Additionally, the DCC opens to allow the engine speed to deviate from the DISG engine speed. In this example, the engine speed changes to idle speed (not shown).

[0050] At time T8, the elapsed time since the request to change the vehicle speed exceeds t. delay2All other conditions described at time T7 are met. Therefore, the engine is shut off at zero RPM by cutting off the spark and fuel supply. The vehicle speed decreases to the new desired vehicle speed because less torque is supplied to the power transmission by the engine and the DISG. The elapsed time since the request to change the vehicle speed is reset to zero when the vehicle speed reaches the new desired vehicle speed.

[0051] At time T9, the driver requests a change in vehicle speed from a lower to a higher speed, as indicated by curve 401. The DISG provides torque to the transmission (not shown), and the elapsed time since the requested change in vehicle speed increases. The state of charge (SOC) remains high, and the DCC remains open. The transmission continues to operate in third gear. The road load torque at the second or new vehicle speed (not shown) is less than the maximum wheel torque that can be provided by the DISG (not shown). The estimated time to change from the first or current vehicle speed to the new or second vehicle speed using only DISG torque (Δt) is shown. spd_chg_DISGHowever, this is longer than a threshold time. Therefore, in response to the request to change the vehicle speed from the first (lower) vehicle speed to the second (higher) vehicle speed, the engine is started. As a result, the engine restarts sooner, preventing the battery from discharging and allowing the vehicle to accelerate at the desired rate.

[0052] In this way, switching between power transmission operating modes can be delayed based on a combination of the time to change from a first vehicle speed to a second vehicle speed, state of charge (SOC), road load torque, maximum DISG torque, and the time since a request to change vehicle speeds was initiated. As a result, mode-changing activity can be reduced.

[0053] Now referring to the Fig. Sections 5A to 5C describe a method for operating a power transmission in a hybrid vehicle. The method of Fig. 5A to 5C can be used as executable instructions stored in non-volatile memory in the system of Fig. 1 and Fig. 2. Furthermore, the procedure of Fig. 5A to 5C in Fig. Provide the operating procedure shown in section 4.

[0054] In procedure 502, procedure 500 assesses whether the hybrid vehicle is in cruise control or speed-sensing mode. The vehicle may enter cruise control mode in response to a request from an operator or controller. During cruise control mode, the driver or controller requests a desired vehicle speed. The engine and / or DISG torque is adjusted to provide the desired vehicle speed. Specifically, the engine and / or DISG torque is adjusted in response to a difference between the desired vehicle speed and the actual vehicle speed. Accordingly, the engine and / or DISG torque is varied to maintain the vehicle speed at a desired vehicle speed.If procedure 500 determines that the vehicle is in cruise control mode, the answer is yes, and procedure 500 continues with 504. Otherwise, the answer is no, and procedure 500 ends.

[0055] In procedure 504, procedure 500 assesses whether a driver or controller has requested a change in vehicle speed from the current vehicle speed to a new vehicle speed. If the requested vehicle speed has changed, the answer is yes, and procedure 500 continues with 508. Otherwise, the answer is no, and procedure 500 continues with 506.

[0056] At 506, procedure 500 continues to operate the vehicle power transmission according to vehicle conditions while maintaining the desired vehicle speed. Furthermore, the power transmission operating modes may remain the same, or the power transmission may change modes in response to vehicle conditions such as battery charge level and road gradient. The engine and / or DISG torque may be adjusted to maintain the desired vehicle speed. For example, if the road gradient increases, the engine and / or DISG torque may be increased to maintain the desired vehicle speed. Procedure 500 continues to the end after the engine and / or DISG torque and the power transmission operating conditions have been adjusted in response to the vehicle's operating conditions.

[0057] In procedure 508, procedure 500 assesses whether the requested change in vehicle speed is an increase. Procedure 500 may determine that the change in vehicle speed is an increase if the new requested vehicle speed is higher than the current vehicle speed. If procedure 500 determines that the requested change in vehicle speed is an increase, torque from the engine and / or DISG is supplied to the power transmission to increase the vehicle speed. Furthermore, if the answer is yes, procedure 500 proceeds to 540. Otherwise, if the requested change in vehicle speed is a decrease, the engine and / or DISG torque may be reduced to decrease the vehicle speed.Additionally, the answer is no and continues procedure 500 with 510.

[0058] At 510, procedure 500 assesses the vehicle's operating conditions to determine operating states of power transmission components that may be desirable for decelerating the vehicle. The road gradient and the available DISG torque at the current DISG speed are two parameters that can affect the efficiency and performance of the power transmission. The amount of available DISG torque varies with the DISG speed. At DISG speeds below a basic DISG speed, the DISG has a maximum torque capacity. At DISG speeds above the basic DISG speed, the DISG provides a constant maximum power output. However, since DISG power is DISG speed multiplied by DISG torque, DISG torque decreases as the DISG speed increases at DISG speeds above the basic DISG speed.

[0059] It may be desirable to define the relationship between vehicle acceleration, engine torque, and DISG torque to determine when it is advisable to change the power transmission's operating modes in response to a request to accelerate or decelerate the vehicle. Vehicle acceleration can be expressed as: MvehAveh=(TENG+TDISG)−(TRL+Rr⋅Mveh⋅g⋅sin(θ))Rr where M veh the mass of the vehicle is, A veh The vehicle acceleration is, T ENG the engine torque is, T DISG the DISG torque is, T RL The road load torque is, R rwhere is the wheel rolling radius, g is the gravitational constant, and θ is the road angle. Assuming that the vehicle acceleration at the time of a requested change in vehicle speed is close to zero, the road load torque at the first (e.g., current) vehicle speed and second (e.g., new) vehicle speed is given by: TRL1=(TENG+TDISG)|Vspd1,gear1,θ=(TRL|vspd1,gear1+RrMvehg sin(θ)) TRL2=(TENG+TDISG)|Vspd2,gear2,θ=(TRL|vspd2,gear2+RrMvehg sin(θ)) where T RL1 The road load torque at the current vehicle speed is T RL2 The road load torque at the new vehicle speed is; T RL1 at the current vehicle speed (V spd1 ), the currently engaged gear ratio (gear1) and the road angle θ are evaluated; T RL2 at the current vehicle speed (V spd2), the currently engaged gear ratio (gear2) and the road angle θ is evaluated.

[0060] The time required for the transition from a first vehicle speed to a second vehicle speed can be determined by: Δtspd_chg=|Vspd1−Vspd2Aveh_des_ave| where Δt spd_chg the time for the transition from the first vehicle speed to the second vehicle speed, and where A veh_des_ave This is an average desired vehicle acceleration rate. The average desired vehicle acceleration rate can be determined empirically and stored in memory for later retrieval and use. The change in wheel torque is given by: ΔTwh=RrMvehAveh_des_ave where ΔT wh The change in wheel torque for changing the vehicle speed from the first vehicle speed to the second vehicle speed is the change in wheel torque.

[0061] Equations 2, 3 and 5 can be combined to obtain the average increase or decrease in torque required to change the vehicle speed from the first vehicle speed to the second vehicle speed; the average torque is given by: T2=(TENG+TDISG)|Vspd2,gear2,θ+RrMvehAveh_des_ave where T2 is the average torque required to move the vehicle to the second vehicle speed. Since a change in torque is the basis for changing the vehicle speed, it can be observed that a power transmission mode control that relies primarily on the power transmission torque to determine the power transmission mode can exhibit power transmission mode change activity.

[0062] Power transmission mode change activity (e.g., frequent switching between power transmission operating modes) can be reduced by assessing, based on additional parameters, whether the power transmission modes need to be changed. Specifically, procedure 500 at 510 assesses whether the road load torque at the second or new desired vehicle speed (T) RL2 ) is smaller than the maximum DISG torque (e.g., maximum DISG torque below the basic speed) T DISGMAX and whether the SOC is smaller than a predetermined minimum SOC (SOC MIN ) and whether the time since the request for a change in vehicle speed (time_since_req) is longer than a predetermined minimum time (t) delay_min If yes, the answer is yes and continues procedure 500 with 514. Otherwise, the answer is no and continues procedure 500 with 512.

[0063] At step 512, procedure 500 closes the DCC if it is open and maintains the current operating state of the engine. For example, if the engine is burning air and fuel, it continues to do so. After closing the DCC and maintaining the current operating state of the engine, procedure 500 proceeds to step 532.

[0064] In 514, the procedure 500 assesses whether the estimated time to change the vehicle speed from the first vehicle speed, in this case a higher vehicle speed, to a second vehicle speed, in this case a lower vehicle speed (Δt) spd_chg ), longer than a predetermined time (t 21_minhi ) or whether the time since the request to change from the first speed to the second speed (time_since_req) is longer than a threshold value of time t delay1 , where t delay1 is longer than t delay_minIf yes, the answer is yes and continues procedure 500 with 524. Otherwise, the answer is no and continues procedure 500 with 516.

[0065] In procedure 500, at 516, the procedure assesses whether the estimated time to change the vehicle speed from the first vehicle speed to the second vehicle speed (Δt) is sufficient. spd_chg_DISG ) is longer than a predetermined time (t 21_minlow ) or whether the time since the request to change from the first speed to the second speed (time_since_req) is longer than a threshold value of time t delay3 , where t delay3 is shorter than t delay1 A logical AND operation is then performed with the logical result, and thus whether the SOC is greater than a battery charge state based on the engine deceleration fuel cut-off mode (SOC). DFSO) performed. If yes, the answer is yes and continues procedure 500 with 518. Otherwise, the answer is no and continues procedure 500 with 522.

[0066] At 522, procedure 500 continues to operate the engine by allowing it to continue burning air and fuel. Furthermore, the DCC remains in a closed state, allowing the engine and the DISG transmission to provide torque. Procedure 500 continues to its conclusion after the engine continues to run and the DCC has closed.

[0067] At 518, procedure 500 conditionally performs an upshift of the transmission gear, whereby the engine burns air and fuel to allow the DISG to deliver the maximum DISG torque T. DISG_MAXto provide (e.g., torque at a DISG speed lower than the basic DISG speed). For example, if the DISG is currently operating at a speed above a basic speed at which the DISG delivers a constant maximum power, the transmission can be shifted into a higher gear while the engine is burning air and fuel, so that the DISG speed can be reduced to a speed lower than the basic DISG speed below which the maximum DISG torque is a constant maximum torque. Procedure 500 continues with 520 after the transmission has been conditionally upshifted (e.g., shifted into a higher gear to reduce the DISG speed, for example, from 2nd to 3rd).

[0068] At 520, procedure 500 ceases supplying spark and fuel to the engine cylinders, and the DCC is closed or held closed. Engine torque can be made available more quickly by allowing the engine to continue rotating. Furthermore, engine fuel consumption is reduced by allowing the engine to rotate without supplying fuel to the engine cylinders. Procedure 500 continues to its conclusion after the engine enters the DFSO and the DCC has closed.

[0069] Accordingly, logic 516 provides a way to determine whether the engine should continue burning air and fuel or enter the Deceleration Fuel Shutoff Operation (DFSO), in which the engine runs without spark or fuel, with the DCC in a closed state. This determination, based on an estimated time to transition from the first vehicle speed to the second vehicle speed and the time since the request to transition from the first vehicle speed to the second vehicle speed, was performed.

[0070] At 524, procedure 500 conditionally performs an upshift of the transmission gear to allow the DISG to deliver the maximum DISG torque (T DISG_MAX) to provide (e.g., maximum DISG torque at a DISG speed lower than the basic DISG speed). Procedure 500 continues with 526 after the transmission has been conditionally upshifted (e.g., shifted into a higher gear to reduce the DISG speed, for example, from 2nd to 3rd).

[0071] At step 526, procedure 500 opens the DCC and adjusts the engine speed to match the engine idle speed or the DISG speed. Adjusting the engine speed to idle allows for fuel savings. Adjusting the engine speed to match the DISG speed reduces the time required to re-couple the engine to the DISG and provides positive torque to the vehicle's wheels. The engine speed can be adjusted to the idle speed or match the DISG speed based on operating conditions such as vehicle speed, road gradient, and road load torque. Procedure 500 continues with step 528 after the DCC has been opened and the engine speed adjusted.

[0072] In procedure 500, 528 assesses whether the time since the request to change the vehicle speed from the first speed to the second speed is longer than the threshold time t. delay2If yes, the answer is yes and continues procedure 500 with 530. Otherwise, the answer is no and continues procedure 500 to the end. The threshold time t delay2 can be a duration that is longer than t delay1 and t delay_min .

[0073] At 530, procedure 500 adjusts the engine speed to zero by stopping the spark and fuel flow to the engine. Switching off the engine saves further fuel, as no fuel is consumed at idle. Procedure 500 continues to its end after the engine has been switched off.

[0074] At 540, procedure 500 assesses whether the road load torque is sufficient at the second or new desired vehicle speed (T). RL2 ) is smaller than the maximum DISG torque (e.g., maximum DISG torque below the basic speed) T DISGMAX and whether the SOC is smaller than a predetermined minimum SOC (SOC MIN) and whether the estimated time to change the vehicle speed from the first vehicle speed to the second vehicle speed (Δt) spd_chg_DISG ) longer than a predetermined time. If yes, the answer is yes and continues procedure 500 with 550. Otherwise, the answer is no and continues procedure 500 with 542.

[0075] In case 542, procedure 500 assesses whether the road load torque is at the second or new desired vehicle speed (T). RL2 ) is smaller than the maximum DISG torque (e.g., maximum DISG torque below the basic speed) T DISGMAX and whether the SOC is larger than a predetermined minimum SOC (SOC MIN ) and whether the estimated time to change the vehicle speed from the first vehicle speed to the second vehicle speed using only DISG (Δt spd_chg_DISG ) is shorter than a predetermined time (t up_max2If yes, the answer is yes and continues procedure 500 with 546. Otherwise, the answer is no and continues procedure 500 with 544. The time to change the vehicle speed from the first vehicle speed to the second vehicle speed using only DISG is given by: Δtspd_chg_DISG=|Vspd1−Vspd2(TDISG_MAX−TRL2)(MvehRr)|

[0076] In procedure 544, procedure 500 operates the power transmission in DISG-only mode, and the transmission remains in the currently selected gear. Power transmission can remain in DISG-only mode if the increase in vehicle speed is small and the DISG has sufficient torque to accelerate the vehicle to the new speed in less than a threshold time. Procedure 500 continues to its conclusion after power transmission has been operated in DISG-only mode.

[0077] At 546, procedure 500 assesses whether the current DISG torque T DISG is smaller than the maximum DISG torque T DISGMAX If yes, the answer is yes and continues procedure 500 with 548. Otherwise, the answer is no and continues procedure 500 with 544.

[0078] At 548, the procedure 500 conditionally shifts up to increase wheel torque, based on the fact that the transmission input torque is at the maximum DISG torque T. DISG_MAX The DISG torque can be increased to the maximum DISG torque in response to a request to provide the desired acceleration or wheel torque. Procedure 500 continues to its conclusion after the wheel torque has been conditionally shifted upwards.

[0079] At 550, procedure 500 assesses whether the engine is not running (e.g., burning air and fuel). If the engine is not running, the answer is yes, and procedure 500 continues with 554. Otherwise, the answer is no, and procedure 500 continues with 552.

[0080] At 552, procedure 500 revs the engine up to the DISG speed and closes the DCC if it is open. The engine revs up and the DCC closes to allow the engine to provide torque to the transmission to accelerate the vehicle from the first vehicle speed to the second vehicle speed. Accordingly, the engine and DISG can provide torque to the transmission to accelerate the vehicle to the new speed. Procedure 500 continues to complete after the engine has revved up to the DISG speed and engine torque has been transmitted to the vehicle wheels.

[0081] At 554, procedure 500 assesses whether the engine is in the Deflation Fuel Shutdown (DFFO) mode. The engine rotates during the DFFO, but spark and fuel are not supplied to the engine cylinders. If procedure 500 assesses that the engine is operating in the DFFO, the answer is yes, and procedure 500 continues to 556. Otherwise, the answer is no, and procedure 500 continues to 558.

[0082] At 556, procedure 500 closes the DCC if it is open and begins supplying spark and fuel to the engine so that it resumes combustion. The engine then provides torque to the transmission and wheels of the vehicle to accelerate it to the new desired speed. Procedure 500 continues to complete after the DCC has closed and the engine is providing positive torque to the power transmission.

[0083] At 558, procedure 500 restarts the engine, accelerates it to the DISG speed, and closes the DCC. The engine can be restarted via a starter motor or by closing the DCC. The engine provides torque to the transmission and the vehicle's wheels to accelerate the vehicle to the new desired speed. Procedure 500 ends after the engine has restarted and positive torque has been delivered to the wheels.

[0084] Consequently, the conditional logic at step 510 and other steps containing time parameters can provide a delay for switching between power transmission modes. Furthermore, the power transmission can switch from engine-only mode to DISG-only mode during reductions in vehicle speed. Similarly, the power transmission can switch from DISG-only mode to engine-only mode when the vehicle accelerates. During some accelerations and decelerations, the power transmission mode can switch from engine-only mode to engine-and-DISG mode and back to engine-only mode.

[0085] In addition, the procedure of Fig. 5A to 5C provide a method comprising: during a speed control mode, delaying a change in the drive sources that supply torque to or absorb torque from a power transmission in response to a time interval since a change in the desired vehicle speed. The method includes that the change in the desired vehicle speed is a decrease in vehicle speed. The method includes that the change in drive sources is from an engine-only operating mode to a starter / generator-only mode integrated into a power transmission. The method further includes delaying the change in the drive sources that supply torque to the power transmission as a further response to an estimated time for changing the vehicle speed from a current speed to a new speed.

[0086] In some examples, the method further includes delaying an engine deactivation time in response to the time elapsed since the desired vehicle speed changed. The method further includes upshifting a transmission in response to the time elapsed since the desired vehicle speed changed. The method further includes delaying an engine entering a deceleration fuel cut-off mode, in which a power transmission disconnect clutch is engaged in response to a time elapsed since the desired vehicle speed changed.

[0087] The procedure of Fig. 5A to 5C further provides: during a cruise control mode, delaying a change in the drive sources that supply torque to or absorb torque from a power transmission in response to an estimate of the time to change from a current vehicle speed to a new vehicle speed. The method includes the possibility that the new vehicle speed is higher than the current vehicle speed. The method includes the possibility that the new vehicle speed is lower than the current vehicle speed. The method further includes delaying the opening of a power transmission disconnect clutch in response to the estimate of the time to change from the current vehicle speed to the new vehicle speed.The procedure involves the cruise control mode adjusting the vehicle speed based on a difference between a desired vehicle speed and an actual vehicle speed.

[0088] In some examples, the method further includes upshifting a transmission to match the speed of a drive-integrated starter / generator (DISG) to a speed at which maximum DISG torque is available, in response to the estimated time to change from the current vehicle speed to the new vehicle speed. The method further includes delaying the opening of a drive-integrated disconnect clutch in response to the time to change from the current vehicle speed to the new vehicle speed.

[0089] As will be recognized by an average expert in the field, the following can be found in the Fig.The procedures described in Sections 5A to 5C represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, and the like. Various steps or functions shown may be executed as such in the sequence presented, in parallel, or, in some cases, omitted. Likewise, the order of processing is not necessarily required to achieve the goals, features, and benefits described herein, but is provided for the sake of simplicity. Although not explicitly shown, a person of average expertise in the field will recognize that one or more of the steps or functions shown may be executed repeatedly, depending on the particular strategy employed.Furthermore, the described actions, procedures, operating processes and / or functions can graphically represent code that is to be programmed into the non-volatile memory of the computer-readable storage medium in the engine control system.

[0090] This concludes the description. Its reading by experts in the field would bring to mind many variations and modifications without altering the essence and scope of the description. For example, I3, I4, I5, V6, V8, V10, and V12 engines running on natural gas, gasoline, diesel, or alternative fuel configurations could make advantageous use of this description.

Claims

[1] Procedure, encompassing: During a speed control mode, delaying a change in the drive sources that provide torque to a power transmission or absorb torque from the power transmission in response to a time interval since a change in a desired vehicle speed. [2] Method according to claim 1, wherein the change in the desired vehicle speed is a reduction in the vehicle speed. [3] Method according to one of the preceding claims, wherein the change of the drive sources is from a motor-only operating mode to a mode of only a starter / generator integrated into a power transmission. [4] Method according to any of the preceding claims, further comprising delaying the change of the drive sources which provide torque to the power transmission as a further response to an estimated time to change the vehicle speed from a present speed to a new speed. [5] Method according to claim 4, further comprising delaying an engine deactivation time in response to the time elapsed since the change in the desired vehicle speed. [6] Method according to any of the preceding claims, further comprising upshifting a transmission in response to the time elapsed since the change in the desired vehicle speed. [7] Method according to any of the preceding claims, further comprising delaying the entry of an engine into a deceleration fuel cut-off mode in which a power transmission disconnect clutch is closed in response to a time since the change in the desired vehicle speed. [8] Procedures, comprehensive: During a speed control mode, delaying a change in the drive sources that provide torque to a power transmission or absorb torque from the power transmission in response to an estimate of the time to change from a current vehicle speed to a new vehicle speed. [9] Method according to claim 8, wherein the new vehicle speed is higher than the current vehicle speed. [10] Method according to claim 8, wherein the new vehicle speed is lower than the current vehicle speed. [11] Method according to any one of claims 8 to 10, further comprising delaying the opening of a power transmission disconnect clutch in response to the estimation of the time to change from the current vehicle speed to the new vehicle speed. [12] Method according to any one of claims 8 to 11, wherein the speed control mode adjusts the vehicle speed based on a difference between a desired vehicle speed and an actual vehicle speed. [13] Method according to any one of claims 8 to 12, further comprising upshifting a transmission to adapt the speed of a starter / generator integrated into a power transmission (DISG) to a speed at which maximum DISG torque is available in response to the estimation of the time to change from the current vehicle speed to the new vehicle speed. [14] Method according to any one of claims 8 to 13, further comprising delaying the opening of a power transmission disconnect clutch in response to the time required to change from the current vehicle speed to the new vehicle speed. [15] System for a hybrid vehicle, comprising: an engine; a starter-generator integrated into a power transmission (DISG); a power transmission disconnect clutch that is mechanically coupled to the engine and the DISG; a gearbox; and a control system containing instructions to switch from a first power transmission mode to a second power transmission mode in response to an estimate of a time to change from a current vehicle speed to a new vehicle speed while the hybrid vehicle is operating in a cruise control mode. [16] System according to claim 15, wherein the first mode is an engine-only mode and wherein the second mode is a DISG-only mode. [17] System according to one of claims 15 to 16, further comprising additional instructions for closing the power transmission disconnect clutch in response to the estimation of the time to change from the current vehicle speed to the new vehicle speed. [18] System according to any one of claims 15 to 17, further comprising additional instructions to upshift the transmission in response to a DISG speed being higher than a DISG speed at which maximum DISG torque is available. [19] System according to any one of claims 15 to 18, further comprising additional instructions for operating the engine in a deceleration fuel cut-off mode in response to the time to change from the current vehicle speed to the new vehicle speed. [20] System according to any one of claims 15 to 19, further comprising additional instructions for delaying the change from the first power transmission mode to the second power transmission mode in response to a time since a change from a first desired vehicle speed to a second desired vehicle speed.

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