Throttle valve adjustment during fuel cut-off

Abstract

Procedure that includes the following: Controlling the position of a throttle valve in an air intake of a power engine, which powers a vehicle, in relation to the commands of an operator of the vehicle; and During a fuel-off shutdown (DFSO) mode, adjusting the throttle opening independently of operator commands to maintain a vehicle speed at a target speed or target speed trajectory, wherein the adjustment includes increasing the throttle opening when the vehicle speed is below a target speed or target speed trajectory, or is expected to fall below a target speed or target speed trajectory, and decreasing the throttle opening if the vehicle speed during the fuel-off shutdown mode increases or is expected to increase above the target speed or target speed trajectory; and when the fuel cut-off mode ends and fuel injection resumes: Adjusting a spark timing control to a late rate in response to an air mass flow rate that exceeds a target air mass flow rate, where the target air mass flow rate is determined based on the commands of the vehicle operator.

Description

Area

[0001] The present description generally refers to methods and systems for controlling a vehicle's engine during the fuel-off shutdown (DFSO) mode. Background / Summary

[0002] During a mode of engine operation generally known as fuel-off shutdown (DFSO), fuel injection to one or more engine cylinders may be interrupted. DFSO mode generally begins when an engine-driven vehicle decelerates and its engine output control (the throttle or accelerator pedal) is in the engine idle position, meaning there is no operator request for additional engine output. Recovery from DFSO mode typically occurs when either the engine speed drops below a predetermined minimum near idle or when the engine control is moved from the idle position to accelerate the engine's rotation and increase output torque.

[0003] The purpose of the DFSO operating mode is to reduce fuel consumption and provide engine braking resulting from frictional resistance and the negative torque exerted on the engine by its load. In engine systems with electronic throttle control (ETC), the throttle position is set based on a target air / fuel ratio. During DFSO, the throttle is typically set to a closed position because no fuel is injected into the engine. However, closing the throttle restricts airflow through the engine and increases the engine braking torque.

[0004] DE 10 2010 033 516 A1 describes a method for operating an internal combustion engine of a motor vehicle during engine braking, comprising the following steps: The degree of depressurization of the accelerator pedal of the motor vehicle is determined. The degree of depressurization of the brake pedal of the motor vehicle is also determined. Furthermore, a throttle valve located in an intake manifold of the internal combustion engine is adjusted depending on the determined degree of depressurization of the accelerator pedal and depending on the determined degree of depressurization of the brake pedal.The throttle valve is adjusted to a position that is at least partially open if the determined degree of depressurization of the brake pedal falls below a first predetermined threshold, and the throttle valve is adjusted to a closed position if the determined degree of depressurization of the brake pedal exceeds a second predetermined threshold.

[0005] DE 43 34 571 A1 describes a device for overrun fuel cut-off in a motor vehicle internal combustion engine, in which, upon resumption of combustion after an overrun fuel cut-off phase, the ignition timing is adjusted from initially "retarded" towards "advanced" to the target ignition timing. From the beginning of the overrun fuel cut-off, the quantities of fresh air entering the exhaust system per power stroke are summed or integrated to determine the total quantity of fresh air in the exhaust system, and the ignition timing adjustment, provided for upon resumption of combustion, occurs from initially "retarded" to the target ignition timing at a rate dependent on the total quantity of fresh air in the exhaust system.

[0006] However, the inventors have recognized potential problems with such systems. For example, the braking torque exerted on the engine by closing the throttle valve can cause the engine speed and / or vehicle speed to decrease by more than the target rate. Consequently, closing the throttle valve during the DFSO (Deep Fuel Stop Operation) can result in excessive deceleration, thus shortening the DFSO event and resulting in a loss of engine efficiency gains. Additionally, there can be a delay in the engine's response to increases in driver-requested torque when exiting the DFSO, as it can take time for the airflow through the intake to increase when the throttle valve opens.

[0007] According to the invention, the problems described above can be solved by a method for controlling a throttle valve during a fuel cut-off mode with the features of claim 1 or 10 or a corresponding system according to claim 15.

[0008] In another embodiment, a method may involve controlling the position of a throttle valve in an air intake of a power engine that propels a vehicle in response to commands from the vehicle operator, and, during a fuel cut-off mode, increasing the throttle valve opening independently of operator commands in response to a signal that a catalyst coupled to an exhaust of the power engine is becoming saturated with oxygen during the fuel cut-off mode. In some examples, the catalyst may include a three-way catalyst containing oxygen storage elements, such as cerium dioxide. In some examples, the method may further include estimating the available storage capacity of the catalyst.The procedure may additionally or alternatively include determining whether the catalyst stores enough oxygen during the fuel cut-off mode to reach its storage capacity or a predetermined percentage thereof. When the fuel cut-off mode is exited, the procedure may further include not injecting fuel into the engine cylinders if the air mass flow rate in the engine is greater than a target air mass flow rate, where the air mass flow rate can be determined based on the vehicle operator's commands and a target air / fuel ratio.

[0009] In this way, excessive engine braking during a DFSO can be reduced, and the DFSO can be extended to achieve fuel savings. Specifically, opening the throttle valve during a DFSO can reduce engine braking torque and allow the vehicle speed to be more accurately aligned with a target speed profile. Furthermore, maintaining the throttle valve in an open position during the DFSO can increase the engine's responsiveness to the driver's torque demands upon exiting the DFSO.

[0010] It should be self-evident that the above summary is provided to introduce, in simplified form, a selection of the 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 that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that eliminate all the disadvantages stated above or in any part of this disclosure. Brief description of the drawings Fig. Figure 1 is a diagram of an exemplary power engine system of a four-stroke engine. Fig. Figure 2 is a scheme of an exemplary power machine system that includes a variable cam timing (VCT) mechanism for adjusting the position of a camshaft of the power machine system. Fig. Figure 3 is a flowchart of an exemplary procedure for adjusting a throttle valve of a power engine system, such as the power engine system according to Fig. 1. Fig. Figure 4 is a flowchart of an exemplary procedure for adjusting a throttle valve of a power engine system, such as the power engine system according to Fig. 1, when exiting a fuel cut-off. Fig. 5 is a map that represents exemplary throttle valve operations during varying operating conditions of the engine. Detailed description

[0011] This section discloses systems and methods for adjusting the throttle valve of a power engine. Exemplary power engine systems are described in the following. Fig. 1 and Fig. Figure 2 shows that, based on input from a vehicle operator, the throttle valve can be adjusted to control the mass airflow to one or more engine cylinders to achieve the torque requested by the operator. If the torque requested by the operator falls below a threshold, the engine may enter fuel cut-off (DFSO). During DFSO, the throttle valve can be adjusted independently of operator commands, as described in the procedure shown in Figure 2. Fig. 3 is described. Furthermore, when the DFSO is exited, the throttle valve can be temporarily operated independently of the operator's commands, as in the exemplary procedure according to Fig. 4 is described. An example of a throttle valve adjustment operation during DFSO and during cylinder combustion is shown in Fig. 5 shown.

[0012] Fig. 1 represents a power engine system 100 for a vehicle. The vehicle can be a road vehicle with drive wheels that are in contact with a road surface. The power engine system 100 includes a power engine 10 comprising several cylinders. Fig. Figure 1 describes such a cylinder or combustion chamber in detail. The various components of the power machine 10 can be controlled by an electronic power machine controller 12.

[0013] The engine 10 comprises the combustion chamber 30 and the cylinder walls 32 with a piston 36 positioned therein and connected to a crankshaft 40. The combustion chamber 30 is shown to be connected to an intake manifold 44 and an exhaust manifold 48 via an intake valve 52 and an exhaust valve 54, respectively. Each intake and exhaust valve can be actuated by an intake cam 51 and an exhaust cam 53. Alternatively, one or more of the intake and exhaust valves can be actuated by an electromechanically controlled valve coil and armature assembly. The position of the intake cam 51 can be determined by an intake cam sensor 55. The position of the exhaust cam 53 can be determined by an exhaust cam sensor 57.

[0014] It is shown that a fuel injector 66 is positioned to inject the fuel directly into the cylinder 30, a process known to those skilled in the art as direct injection. Alternatively, the 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 the liquid fuel proportionally to the pulse width of a signal FPW from the controller 12. The fuel is supplied to the fuel injector 66 by a fuel system (not shown) comprising a fuel tank, a fuel pump, and a fuel distributor. An operating current is supplied to the fuel injector 66 by a driver 68, which responds to the controller 12.Additionally, it is shown that the intake manifold 44 is connected to an electronic throttle valve 62, which sets the position of a throttle plate 64 to control the airflow to the engine cylinder 30. This can include controlling the airflow of the charged air from an intake charge chamber 46. The electronic throttle valve 62 can be an electric motor mechanically coupled to the throttle plate 64. The electrical input to the throttle valve 62 can be converted into a mechanical rotary motion, which can be used to rotate the position of the throttle plate 64.

[0015] The throttle valve 62 can adjust the position of the throttle plate 64 based on signals received from the controller 12. Consequently, the controller 12 can determine a target position of the throttle plate 64 based on a target torque of the power machine and the operating conditions of the power machine, and send signals to the throttle valve 62 to adjust the position of the throttle plate 64 to the target position.

[0016] Ambient air is drawn into the combustion chamber 30 via the inlet duct 42, which may contain an air filter 56. Consequently, the air first enters the inlet duct 42 through the air filter 56. If a compressor 162 is included, it draws air from the air inlet duct 42 to supply compressed air to the charge chamber 46 via an air filter 56. Fig. 1 (not shown) compressor outlet pipe. In some examples, the air inlet duct 42 may contain an air box (not shown) with a filter. In one example, the compressor 162 may be a turbocharger, with the power for the compressor 162 being derived from the flow of exhaust gases through the turbine 164. Specifically, the exhaust gases may rotate the turbine 164, which may be coupled to the compressor 162 via a shaft 61.

[0017] In alternative embodiments, however, the compressor 162 can be a supercharger, with the power for the compressor 162 being taken from the crankshaft 40. Consequently, the compressor 162 can be coupled to the crankshaft 40 via a mechanical linkage, which can be any suitable linkage for mechanically coupling the crankshaft 40 to the compressor 162, such as a belt. A portion of the rotational energy output by the crankshaft 40 can be transmitted to the compressor 162 via the mechanical linkage to drive it. In still further examples, the engine 10 can omit the compressor 162, and the engine 10 itself cannot be a supercharged engine.

[0018] The distributorless ignition system 90 provides a spark to the combustion chamber 30 via a spark plug 92 in response to the controller 12. The ignition system 90 can include an induction coil ignition system in which an ignition coil transformer is connected to each spark plug of the engine. A universal exhaust gas oxygen sensor (UEGO sensor) 126 is shown coupled to the exhaust manifold 148 upstream of an exhaust catalyst 70. Alternatively, the UEGO sensor 126 can be replaced by a dual-state exhaust gas oxygen sensor. While the illustrated example shows the UEGO sensor 126 upstream of the turbine 164, it is recognized that in alternative embodiments the UEGO sensor can be positioned downstream of the turbine 164 and upstream of the catalyst 70 in the exhaust manifold.

[0019] The catalyst 70 can contain multiple catalyst modules in one example. In another example, multiple exhaust gas purification devices, each with multiple modules, can be used. The exhaust gas catalyst 70 can be a three-way catalyst in one example. Consequently, the catalyst 70 can be configured to reduce nitrogen oxides (NOx) and oxidize carbon monoxide (CO) and unburned hydrocarbons (HCs) to water and carbon dioxide. The air / fuel ratio entering the engine 10 can be regulated by the controller 12 so that the air / fuel ratio continuously cycles precisely around the stoichiometric air / fuel ratio. In some examples, the stoichiometric air / fuel ratio can be approximately 14.7:1.In this way, the exhaust gas passing over the catalytic surfaces of catalyst 70 is alternately rich in oxygen and poor in oxygen to promote the nearly simultaneous oxidation and reduction reactions. Catalyst 70 can be designed as a ceramic monolith with a honeycomb structure. Furthermore, the surfaces of catalyst 70 can include one or more precious metal materials to retain the catalytic materials used in the oxidation and reduction reactions. Suitable elements to be used to retain the catalytic materials can include aluminum oxide, titanium oxide, silicon dioxide, or a mixture of silicon dioxide and aluminum oxide. The catalytic materials used in carrying out the oxidation and reduction reactions of catalyst 70 can be one or more elements made of platinum, palladium, rhodium, cerium, iron, manganese, and nickel.

[0020] When the engine 10 operates lean, with the air-fuel ratio greater than stoichiometric, excess oxygen can be stored in the catalyst 70 for later use during the conditions when the engine 10 operates rich and the exhaust gases are oxygen-poor. Therefore, the catalyst 70 can contain an oxygen storage material, such as cerium dioxide (CeO2), to store oxygen during the lean operating conditions of the engine. Consequently, the catalyst 70 can temporarily store oxygen during the oxygen-rich phases of the air-fuel cycles to provide oxygen for oxidation reactions when the exhaust gas is temporarily oxygen-poor. However, the catalyst 70 can only store oxygen up to a certain threshold amount.Consequently, catalyst 70 can be described as saturated when the oxygen content of catalyst 70 has reached the threshold where essentially no additional oxygen can be stored by the catalyst.

[0021] Furthermore, the temperature, Tcat1, of the catalyst 70 can be estimated based on the outputs of a temperature sensor 124 coupled to the catalyst 70. Consequently, the temperature sensor 124 can be physically coupled to the catalyst 70 and configured to measure / estimate the catalyst's temperature. During DFSO, the catalyst's temperature may decrease because the exhaust gas temperature may be reduced. In an alternative embodiment, however, the temperature Tcat1 can be inferred from the engine operation.

[0022] The Controller 12 is in Fig. Figure 1 shows a microcomputer comprising a microprocessor unit 102, input / output ports 104, a read / write memory 106, a read / write memory 108, a hold memory 110, and a conventional data bus. It is shown that, in addition to the signals previously discussed, the controller 12 receives 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 input device 130 for sensing an input device pedal position (PP) set by an operator 132 of the vehicle; and a knock sensor (not shown) for determining the ignition of the exhaust gases. a measured value of the engine manifold pressure (MAP) from a pressure sensor 121 coupled to the intake manifold 144;a measured value of the boost pressure from a pressure sensor 122 coupled to the boost pressure chamber 146; a power engine position sensor from a Hall effect sensor 118 that scans the position of the crankshaft 40; a measured value of an air mass entering the power engine from a sensor 120 (e.g. a hot-wire air flow meter);and a measured value of the throttle position from a sensor 58. Atmospheric pressure can also be sampled for processing by the controller 12 (the sensor is not shown). In a preferred aspect of the present description, an engine position sensor 118 generates a predetermined number of equally spaced pulses at each revolution of the crankshaft, from which the engine speed (RPM) can be determined. The input device 130 can include an accelerator pedal and / or a brake pedal. The output from the position sensor 134 can be used to determine the position of the accelerator pedal and / or the brake pedal of the input device 130 and therefore to determine a target engine torque. Consequently, a target engine torque requested by the operator 132 of the vehicle can be determined based on the pedal position of the input device 130.

[0023] The controller 12 can determine a target position of the throttle plate 64 based on inputs received from the input device 130 and the pedal position signal (PP signal) and / or vehicle weight and / or road gradient and / or transmission gear, etc. In this particular example, the position of the throttle plate 64 can be varied by the controller 12 via a signal supplied to an electric motor or actuator contained within the throttle valve 62, a configuration generally referred to as electronic throttle control (ETC). In this way, the throttle valve 62 can be operated to vary the intake air supplied to the combustion chamber 30 among the other engine cylinders.More specifically, the throttle valve 62 can be an electric motor, which may be mechanically coupled to the throttle plate 64, for adjusting the position of the throttle plate 64 based on the signals received from the controller 12. Consequently, the electrical input to the throttle valve 62 can be converted into mechanical rotational energy, which is used to adjust the position of the throttle plate 64 and to vary the airflow to the engine cylinder 30.

[0024] However, during certain operating conditions, such as while idling or driving downhill, the engine 10 may enter a fuel cut-off switch-off (DFSO) mode, in which fuel injection to cylinder 30 may cease. In some examples, the throttle plate 64 may be set to an open position during DFSO if the vehicle speed is below a target trajectory or is expected to fall below a target trajectory, as described below with respect to the Fig. 3 and Fig. 4 is explained in more detail. In other examples, the throttle plate 64 may be set to a more closed position during a DFSO if the vehicle speed is not below the target trajectory or is not expected to fall below the target trajectory. In still other examples, the throttle plate 64 may only be set to a more open position during a DFSO if the vehicle speed is below a target trajectory or is expected to fall below a target trajectory, and it is predicted that the exhaust catalyst 70 will become saturated during the DFSO event.

[0025] In some embodiments, the power unit can be coupled to an electric motor / battery system in a hybrid vehicle. The hybrid vehicle can have a parallel configuration, a series configuration, or a variation or combination thereof.

[0026] During operation, each cylinder in the engine 10 typically goes through a four-stroke cycle: the cycle includes the intake stroke, the compression stroke, the power stroke, and the exhaust stroke. Consequently, the engine 10 can be a four-stroke engine. Generally, the piston 36 can move from top dead center (TDC) to bottom dead center (BDC) during the intake and power strokes. Conversely, the piston 36 can move from BDC to TDC during the compression and exhaust strokes. During the intake stroke, the exhaust valve 54 can generally be closed and the intake valve 52 can be open, allowing gases from the engine inlet to enter cylinder 30. During the compression and power strokes, the intake valve 52 can be closed and the exhaust valve 54 can remain closed. During the exhaust stroke, the inlet valve 52 can remain closed and the exhaust valve 54 can be open.The positions of valves 52 and 54 can be changed by a (in . Fig. 1. The camshaft (not shown) must be adjusted. As explained below regarding Fig. As described in more detail in section 2, the position of the camshaft, and therefore the position of valves 52 and 54, can be adjusted depending on the operating conditions of the engine. Specifically, the position of the camshaft relative to the crankshaft 40 can be adjusted by changing the position of the camshaft.

[0027] The crankshaft 40 converts the piston movement into a torque of the crankshaft. During the exhaust stroke, the exhaust valve 54 is open to expel the burnt air-fuel mixture to the exhaust manifold 48. The gases can then flow from the exhaust manifold 48 through an exhaust port 80 to the turbine 164. Furthermore, the exhaust gases can pass the catalyst 70 before being emitted into the atmosphere. It should be noted that the above is described only as an example and that the opening and / or closing timing of the intake and exhaust valves can vary, for example, to provide positive or negative valve overlap, late intake valve closing, or various other configurations.

[0028] Fig. Figure 2 shows an exemplary embodiment of a power machine 200, which includes a controller 202, a variable cam timing system 232 (VCT system), and a power machine block 206 with multiple cylinders 210. The power machine 200 can be an example of the one described in Fig. The power machine 10 described in section 1 is shown. Consequently, it shows Fig. 2 an exemplary VCT system that is in the Fig. The power unit 10 described in Section 1 can be used to adjust the timing of the opening and closing of the inlet valve 52 and the exhaust valve 54 of the power unit 10. The power unit 200 is shown to have an inlet manifold 266 configured to supply intake air and / or fuel to cylinders 210a-d, and an exhaust manifold 268 configured to discharge the combustion products from cylinders 210. An ambient air flow can enter the intake system through an inlet air duct 260, and the flow rate and / or pressure of the intake air can be controlled at least partially by a main throttle valve (not shown).

[0029] The engine block 206 contains several cylinders 210a-d (here four). In the example shown, all cylinders are located in a common engine row. In alternative embodiments, the cylinders can be distributed between several rows. For example, cylinders 210a-b can be located in a first row, while cylinders 210c-d can be located in a second row. Each of the cylinders 210a-d can have a spark plug and a fuel injector to supply fuel directly to the combustion chamber, as shown above. Fig. The engine 200 contains, as described in Section 1, one or more valves. Furthermore, each of the cylinders 210a-d can be operated by one or more valves. In the present example, each cylinder 210a-d contains a corresponding intake valve 212 and an exhaust valve 222. As will be elaborated below, the engine 200 also contains one or more camshafts 238, 240, each camshaft being capable of actuating the intake and / or exhaust valves of several cylinders coupled to a common camshaft.

[0030] Each inlet valve 212 is operable between an open position, which allows intake air into the corresponding cylinder, and a closed position, which essentially blocks the intake air from the cylinder. Furthermore, it shows Fig. 2, how the intake valves 212 of cylinders 210a-d can be actuated by a common intake camshaft 238. The intake camshaft 238 can be incorporated into an intake valve actuation system 214. The intake camshaft 238 includes the intake cam projections 216, which have a lift profile for opening the intake valves 212 for a defined intake duration. In some embodiments (not shown), the camshaft can include additional intake cam projections with an alternative lift profile, which allows the intake valves 212 to be opened for an alternative lift and / or duration (also referred to herein as a cam profile switching system). Based on the lift profile of the additional cam projection, the alternative duration can be longer or shorter than the defined intake duration of the intake cam projection 216.

[0031] The lift profile can influence the cam lift height, cam duration, opening timing, and / or closing timing. A controller can change the intake valve duration by longitudinally moving the intake cam projections 216 and switching between cam profiles. In another embodiment, a controller can change the intake valve duration by engaging or disengaging rocker arms, valve tappets, or other mechanisms between the cam projections 216 and the intake valves 212.

[0032] In the same way, each exhaust valve 222 can be actuated between an open position, which allows exhaust gas to escape from the corresponding cylinder, and a closed position, which essentially keeps the gas inside the cylinder. Fig. Figure 2 further shows how the exhaust valves 222 of cylinders 210a-d can be actuated by a common exhaust camshaft 240. The exhaust camshaft 240 can be incorporated into an exhaust valve actuation system 224. The exhaust camshaft 240 includes the exhaust cam projections 226, which have a lift profile for opening the exhaust valves 222 for a defined exhaust duration. In some embodiments (not shown), the camshaft can include additional exhaust cam projections with an alternative lift profile, allowing the exhaust valves 222 to be opened with an alternative lift and / or for an alternative duration. Based on the lift profile of the additional cam projection, the alternative duration can be longer or shorter than the defined exhaust duration of the exhaust cam profile 226. The stroke profile can influence the cam stroke height, the cam duration, the timing of opening and / or the timing of closing.A controller can be able to change the exhaust valve duration by longitudinally moving the exhaust cam projections 226 and switching between the cam profiles. In a further embodiment, a controller can be able to change the exhaust valve duration by engaging or disengaging rocker arms, valve tappets, or other mechanisms between the cam projections 226 and the exhaust valves 222.

[0033] It is recognized that, while the illustrated example shows a common intake camshaft 238 coupled to the intake valves of each cylinder 210a-d and a common exhaust camshaft 240 coupled to the exhaust valves of each cylinder 210a-d, in alternative embodiments the camshafts may be coupled to subsets of cylinders and multiple intake and / or exhaust camshafts may be present. For example, a first intake camshaft may be coupled to the intake valves of a first subset of cylinders (e.g., to cylinders 210a-b), while a second intake camshaft may be coupled to the intake valves of a second subset of cylinders (e.g., to cylinders 210c-d). Similarly, a first exhaust camshaft can be coupled to the exhaust valves of a first subset of the cylinders (e.g.a second exhaust camshaft can be coupled to the exhaust valves of a second subset of cylinders (e.g., cylinders 210a-b), while a second exhaust camshaft can be coupled to the exhaust valves of a second subset of cylinders (e.g., cylinders 210c-d). Furthermore, one or more intake and exhaust valves can be coupled to each camshaft. The subset of cylinders coupled to the camshaft can be based on their position along the 206 engine row, their firing order, the engine configuration, and so on.

[0034] The intake valve actuation system 214 and the exhaust valve actuation system 224 may further include valve pushrods, rocker arms, valve tappets, etc. Such devices and features can control the actuation of the intake valves 212 and the exhaust valves 222 by converting the rotary motion of the cams into a translational motion of the valves. As previously discussed, the valves may also be actuated by means of additional cam profiles on the camshafts, the cam profiles being able to provide varying cam lift height, varying cam duration, and / or varying cam timing between the different valves. However, alternative camshaft arrangements (overhead and / or with valve pushrods) could be used if desired. Furthermore, in some examples, each of the cylinders 210a-d may have more than one exhaust valve and / or intake valve.In further examples, both the exhaust valve 222 and the intake valve 212 of one or more cylinders can be actuated by a common camshaft. Even further, in some examples, some of the intake valves 212 and / or the exhaust valves 222 can be actuated by their own independent camshaft or other device.

[0035] The power unit 200 can include variable valve timing systems, such as the variable cam timing system 232 (VCT). The VCT system 232 can be a dual independent variable cam timing system to modify the intake and exhaust valve timing independently. The VCT system 232 includes an intake camshaft adjuster 234, coupled to the common intake camshaft 238, for modifying the intake valve timing, and an exhaust camshaft adjuster 236, coupled to the common exhaust camshaft 240, for modifying the exhaust valve timing. The VCT system 232 can be configured to advance or retard the valve timing by advancing or retarding the cam timing, and can be controlled via signal lines by the controller 202.The VCT system 232 can be configured to vary the timing of the valve opening and closing events by varying the relationship between the crankshaft position and the camshaft position. For example, the VCT system 232 can be configured to rotate the intake camshaft 238 and / or the exhaust camshaft 240 independently of the crankshaft to advance or retard the valve timing. In some embodiments, the VCT system 232 can be a cam torque-actuated device configured to rapidly change the cam timing. In some embodiments, the valve timing, such as the closing of the intake valves (IVC) and the closing of the exhaust valves (EVC), can be varied by a continuously variable valve lift (CVVL) device.

[0036] The valve / cam control devices and systems described above can be hydraulically actuated, electrically actuated, or a combination thereof. For example, the position of the camshaft can be changed via cam phase adjustment by an electric actuator (e.g., an electrically actuated camshaft adjuster) with an accuracy exceeding that of most hydraulically actuated camshaft adjusters. The signal lines can send control signals to the VCT system 232 and receive a cam timing control and / or cam selection measurement from the VCT system 232.

[0037] Because in the illustrated example the intake valves of all cylinders 210a-d are actuated by a common intake camshaft, a change in the position of the intake camshaft 238 affects the intake valve position and timing of all cylinders. Similarly, because the exhaust valves of all cylinders 210a-d are actuated by a common exhaust camshaft, a change in the position of the exhaust camshaft 240 affects the exhaust valve position and timing of all cylinders. A change in the position of the intake and / or exhaust camshaft that, for example, advances the (intake or exhaust) valve timing of a first cylinder 210a, simultaneously advances the (intake or exhaust) valve timing of the remaining cylinders 210b-d. However, the valve timing adjustment can be performed on one or more cylinders independently of the valve timing of the remaining cylinders.

[0038] As described above, shows Fig. 2. A non-restrictive example of an internal combustion engine and its associated intake and exhaust systems. It should be recognized that in some embodiments, the engine may include, among other things, more or fewer combustion cylinders, control valves, throttle valves, and compression devices. Exemplary engines may have cylinders arranged in a "V" configuration. Furthermore, a first common camshaft may actuate the valves for a first set of cylinders in a first row, while a second camshaft may actuate the valves for a second set of cylinders in a second row. That is, a common camshaft of a cam actuation system (e.g., a VCT system) may be used to actuate the valve operation of a group of cylinders.

[0039] Consequently, it illustrates Fig. 2 Variable valve timing systems that can be used to adjust the events of the opening, closing, opening, and closing of the intake valves of one or more cylinders of a power engine.

[0040] In some embodiments, the above regarding the Fig. 1 and Fig. 2 described power engine systems provide a system comprising a power engine containing a variable camshaft timing system, a catalyst positioned in an exhaust port of the power engine, an ETC system with a throttle plate and an actuator for adjusting the position of the throttle plate, and a controller containing instructions to adjust the position of the throttle plate based on operator commands during cylinder combustion and to not adjust the position of the throttle plate based on operator commands during a DFSO when no fuel is injected into one or more power engine cylinders.

[0041] Fig. Figure 3 shows a flowchart of an exemplary procedure 300 for adjusting the position of a throttle plate (e.g., the one in Fig. 1 throttle plate 64) shown before and during entry into a DFSO mode. If, during engine operation, the torque requested by the driver falls below a threshold, torque can be supplied to the engine cylinders (e.g., the one shown in Fig. No fuel is injected into engine cylinder 30 (shown in 1) to reduce fuel consumption. Consequently, cylinder combustion may cease during a DFSO. In some examples, the throttle plate may be set to a more closed position during the DFSO to reduce airflow to the engine cylinders. However, closing the throttle plate may impart braking torque to an engine (e.g., the one shown in 1). Fig. The braking torque applied to the power unit shown (10) can cause a vehicle in which the power unit is located to decelerate beyond a target rate. Therefore, in some examples, the throttle plate may be set to a more open position during the DFSO to reduce the braking torque applied to the power unit and thereby reduce the rate at which the vehicle decelerates.

[0042] The instructions for executing procedure 300 and the rest of the procedures contained herein can be based on the instructions stored in a memory of the controller and in connection with the information provided by the sensors of the power machine system, such as those mentioned above. Fig. 1. Sensors described, received signals by a controller (e.g., the one in Fig. The controller (12) shown in section 1 can be used to operate the power machine actuators of the power machine system. The controller can use these actuators to adjust the power machine operation according to the procedures described below. In particular, the controller can adjust the position of the throttle plate in response to a signal from one or more position sensors (e.g., the one shown in section 1). Fig. 1 sensor 134 shown) of an input device (e.g. the one in Fig. The controller can adjust the received signals (shown in input device 130) and the instructions stored in the controller's memory. Specifically, to adjust the position of the throttle plate, the controller can send signals to an actuator (e.g., the one shown in 1) and the instructions stored in the controller's memory. Fig. 1 throttle valve 62), which is mechanically coupled to the throttle plate, sends signals. In response to the signals received from the various engine sensors, the controller can determine a target throttle position and send signals to the throttle plate actuator to adjust the throttle plate to the target position.

[0043] Procedure 300 begins at 302, which involves estimating and / or measuring the operating conditions of the engine. The operating conditions of the engine may include an engine speed, a throttle position sensor (e.g., the one in Fig. 1 sensor 58) estimated throttle position, a torque commanded by the operator which can be estimated based on the outputs from the input device position sensor, an oxygen storage level in an exhaust catalyst (e.g. the one in Fig. 1 exhaust catalyst 70), a fuel injection quantity, a measurement from an air mass flow sensor (e.g. the one in Fig. 1 sensor shown (120) contains certain inlet air mass flow, etc.

[0044] After estimating and / or measuring the operating conditions of the engine, the procedure can continue from 300 to 304, which involves adjusting the throttle valve based on a target position of the electronic throttle control (ETC). As above regarding Fig. As described in section 1, the ETC target position can be determined based on input from a vehicle operator (e.g., the person described in section 1). Fig. The ETC target position (as shown in Figure 1) can be determined via the input device by the vehicle operator (132). In other examples, the ETC target position can be determined additionally or alternatively based on vehicle weight, gradient on which the vehicle is traveling, etc.

[0045] Specifically, the throttle valve can be adjusted between a fully closed first position and a fully open second position, whereby essentially no air can flow past the throttle valve to the engine cylinder when the throttle valve is in the closed first position. Airflow past the throttle valve can increase as the throttle valve is deflected further from the closed first position to the open second position. Furthermore, a gap can be created between the throttle valve and an intake port (e.g., the one in the Fig. The opening formed by the inlet channel 42 shown in 1 increases with an increasing deflection away from the closed first position to the open second position.

[0046] The throttle valve can be continuously variable and can be set to any position between the fully closed first position and the fully open second position. Furthermore, the controller can adjust the throttle valve position by sending signals to the throttle valve actuator to adjust the throttle plate. Specifically, a pulse-width modulated (PWM) signal can be transmitted to the actuator. In one example, the PWM signal can have a frequency of 10 Hz. In another example, the throttle plate actuator can receive a PWM signal of 20 Hz.

[0047] The ETC target position can be deflected from the closed first position to the open second position as the input device is increasingly depressed. Consequently, when the vehicle operator depresses the input device (e.g., the accelerator pedal), the throttle position can be adjusted to a more open position. Based on the torque applied by the operator, which can be estimated from the outputs of the position sensor configured to measure the input device position, the controller can determine the ETC position and send signals to the throttle plate actuator to adjust the throttle plate to the ETC target position.

[0048] Procedure 300 can then proceed to 306, which includes determining whether a pedal release event has occurred. Determining whether a pedal release event has occurred may include determining whether the input device position is past a first threshold position. In some examples, the first position may be a position of the input device where the input device is not depressed. Consequently, procedure 306 may include determining whether the operator-applied torque is below a threshold. If, at 306, the input device is depressed and, consequently, the operator-applied torque is not below the threshold, then procedure 300 can return to 304 and continue to adjust the throttle position based on the ETC setpoint.However, if a pedal release is detected, whereby the input device cannot be depressed and consequently the torque commanded by the operator can be less than the threshold, then the procedure to 308 can proceed and the DFSO can begin.

[0049] The onset of DFSO can involve shutting off fuel injection. Consequently, one or more fuel injectors (e.g., those in) may fail. Fig. 1. Fuel injector 66 (shown) is switched off, so that no fuel is injected into one or more engine cylinders. The method as such may, at 308, include disabling cylinder combustion and stopping fuel injection. In some examples, the method at 308 may additionally include closing the throttle valve. Consequently, in some examples, the throttle valve may be closed when the DFSO begins.

[0050] The procedure can then continue from 300 to 310, which involves estimating the pedal release duration based on vehicle speed and / or engine braking and / or road gradient and / or other factors. For example, the duration of the pedal release event, and therefore the DFSO, may increase with increasing gradient angles. Furthermore, the duration of the pedal release event may increase with increasing initial vehicle speed at which the pedal release event began. Other factors may include the presence of traffic lights and / or stopped vehicles ahead on the road, based on information from maps, vehicle-to-vehicle or infrastructure-to-vehicle communication, and / or onboard sensors such as cameras, radar, etc.

[0051] After estimating the duration of the pedal release event at 310, the procedure can proceed from 300 to 312, which includes determining whether the estimated vehicle speed is below a target vehicle speed or whether it is predicted / foreseen that the estimated vehicle speed will fall below a target vehicle speed. The vehicle speed can be estimated based on one or more sensors in the power unit configured to measure vehicle speed, such as a crankshaft position sensor. The target vehicle speed can be a speed determined based on a lookup table stored in the controller's memory and can be a function of the expected pedal release duration. Consequently, a set of curves or profiles of the target vehicle speed can be stored in the controller's memory.Put another way, a known relationship between the vehicle's initial velocity upon entering a DFSO, an expected pedal release duration, and a deceleration rate can be stored in the controller's memory. Based on this known relationship, a target deceleration of the vehicle's velocity over a given duration can be determined. The trajectory of the target vehicle velocity, as such, can be determined for the vehicle upon entering the DFSO based on the vehicle's initial velocity at the start of the DFSO event and the expected pedal release duration.

[0052] If the estimated vehicle speed is not below the target vehicle speed and / or is not expected to fall below the target vehicle speed, then procedure 300 to 320 can continue, which includes closing the throttle. The predicted vehicle speed can be estimated based on the current vehicle speed and the engine operating conditions. For example, the expected vehicle speed can be estimated based on the road gradient, engine load, throttle position, alternator load, etc. Specifically, the predicted vehicle speed trajectory may decrease with increases in engine load, alternator load, road gradient, throttle closing, etc.In some examples, procedure 300 at 320 may involve closing the throttle valve to the fully closed first position. In other examples, however, procedure 320 may involve adjusting the position of the throttle plate to a further closed position, but not to the fully closed first position. In still other examples, procedure 320 may involve maintaining the position of the throttle valve. If the vehicle speed is approximately the same as the target speed, then specifically, the position of the throttle valve at 320 may be maintained. Consequently, if the vehicle speed is equal to and / or substantially the same as the target speed, then procedure 300 may involve maintaining the position of the throttle valve.

[0053] However, if the estimated vehicle speed is less than the target vehicle speed, or if the estimated vehicle speed is expected to decrease below the target vehicle speed, then procedure 300 to 314 continues, which may include estimating the current exhaust catalyst temperature. The exhaust catalyst temperature can be estimated based on the outputs from an exhaust catalyst temperature sensor (e.g., the one in Fig. The oxygen storage levels of the exhaust catalyst can be estimated either from the temperature sensor 124 shown in Figure 1, which is coupled to the exhaust catalyst, or based on the operating conditions of the engine, such as the engine speed, the intake air mass flow, the air / fuel ratio, the spark timing control, etc. In a further embodiment, the method at 314 can additionally or alternatively include estimating the current oxygen storage levels of the exhaust catalyst. The oxygen storage levels of the exhaust catalyst can be estimated based on the temperature of the exhaust catalyst and / or an air / fuel ratio and / or an exhaust oxygen content and / or an age of the catalyst, etc.

[0054] After estimating the exhaust catalyst temperature and / or the exhaust catalyst oxygen storage levels, the procedure can continue from 300 to 316, which involves estimating the amount of the decrease in the exhaust catalyst temperature during the DFSO / pedal release event. The exhaust catalyst temperature can decrease during DFSO because the exhaust gas temperature may be reduced. Consequently, the catalyst temperature during pedal release can be predicted by estimating the current catalyst temperature and estimating the amount of the decrease in catalyst temperature during the DFSO event. Estimating the amount of the catalyst temperature decrease can be determined based on the throttle position, the estimated mass airflow, the initial catalyst temperature at the start of DFSO, and the duration of the DFSO event.The magnitude of the catalyst temperature decrease may be greater with the throttle open than with the throttle closed because the intake air mass flow may be greater with the throttle open. As such, the estimates of the magnitude of the catalyst temperature decrease during the DFSO event may increase with increasing degrees of throttle opening during the DFSO event. Specifically, in one example, the method at 316 may include estimating the magnitude of the catalyst temperature decrease during the DFSO event with the throttle closed. In another embodiment, the method at 316 may include estimating the magnitude of the catalyst temperature decrease during the DFSO event with the throttle open.

[0055] In a further embodiment, the method at 316 can additionally or alternatively include estimating the amount of the increase in the oxygen storage levels of the exhaust catalyst during the DFSO / pedal release event. Because no fuel is injected into the engine during DFSO, the oxygen content of the exhaust catalyst can increase. Estimating the amount of the increase in the oxygen storage levels of the exhaust catalyst can be determined based on the position of the throttle valve, the estimated air mass flow, the oxygen content of the exhaust catalyst, the duration of the DFSO event, etc. Consequently, the oxygen storage levels of the exhaust catalyst can increase with increases in the duration of the DFSO event and increases in the air mass flow rate.Consequently, by estimating the current oxygen storage levels of the exhaust catalyst and estimating the amount of the increase in storage levels during the DFSO event, the oxygen storage levels in the catalyst during pedal release can be predicted.

[0056] Method 300 can continue from 316 to 318, which may include determining whether the predicted catalyst temperature will remain above a temperature threshold with the throttle open. The threshold may represent a catalyst temperature below which the catalyst efficiency is reduced, causing emissions to increase above a threshold. The catalyst efficiency may be reduced at sufficiently low operating temperatures. As such, emission levels may be increased. Opening the throttle during the DFSO may exacerbate catalyst cooling. However, if the catalyst temperature is predicted to remain above the threshold during the DFSO event, even with the throttle held open, then the throttle may be opened during the DFSO to minimize engine braking without increasing exhaust emission levels.

[0057] In a further embodiment, the method at 318 can additionally or alternatively include determining whether the predicted catalyst temperature during the DFSO event falls below the temperature threshold with the throttle valve closed. If it is predicted that the catalyst temperature will fall below the threshold during the DFSO event, even if the throttle valve is kept closed, then the throttle valve can be opened during the DFSO to reduce engine braking without increasing exhaust emission levels by more than they would with the throttle valve closed.

[0058] In a further embodiment, the method at 318 may additionally or alternatively include determining whether the predicted oxygen storage levels in the catalyst during the DFSO event exceed an oxygen storage threshold. The threshold oxygen storage level may represent an oxygen level in the catalyst above which the catalyst may be saturated. Consequently, the oxygen storage threshold at 318 may represent the saturation point of the catalyst, above which essentially no additional oxygen can be stored by the catalyst. In other examples, however, the oxygen storage threshold at 318 may be lower than the saturation point of the catalyst.

[0059] If it is predicted at 318 that the catalyst temperature will not fall below the threshold if the throttle valve is open, or if the catalyst temperature falls below the threshold during the DFSO event even if the throttle valve is kept closed, method 300 can proceed to 322, which includes opening the throttle valve. In a further embodiment, method 300 can additionally or alternatively proceed to 322 if the oxygen storage levels in the catalyst are greater than the oxygen storage threshold at 318.However, if it is predicted that the catalyst temperature will remain above the threshold if the throttle valve is held closed during the DFSO event, and that the catalyst temperature will fall below the threshold if the throttle valve is held open, then procedure 300 can proceed to 320 and adjust the throttle valve to a more closed position. In a further embodiment, procedure 300 can proceed additionally or alternatively to 320 if the oxygen storage levels in the catalyst do not exceed the oxygen storage threshold at 318.

[0060] In some examples, opening the throttle valve at 322 may involve opening the throttle valve to the fully open second position or to a maximum opening that does not produce an undesirable intake noise for the operator. In other examples, however, opening the throttle valve may involve adjusting the throttle valve position to a more open position, but not to the fully open second position. Furthermore, in the examples where the throttle valve is open but not to the fully open second position, the amount the throttle valve is open may be based on the difference between the estimated vehicle speed and the vehicle's target speed, as determined at 312.If opening the throttle valve during the DFSO (Deep Fuel Steady Off-Season) does not cause the catalyst temperature to reach the temperature threshold, or if the catalyst temperature reaches the temperature threshold during the DFSO with the throttle valve closed, the throttle valve can consequently be adjusted from the fully closed first position to a more open position. Additionally or alternatively, the throttle valve can be adjusted from the fully closed first position to a more open position if the oxygen levels in the catalyst reach the oxygen storage threshold during the pedal release event. The amount the throttle valve is opened can be proportional to the difference between the estimated vehicle speed and the vehicle's target speed.For increases in the difference between the estimated vehicle speed and the target vehicle speed, the amount by which the throttle valve is opened can increase. If the estimated vehicle speed during the DFSO is below the target speed, or if it is predicted that the estimated vehicle speed during the DFSO will fall below the target speed, and the oxygen catalyst reaches its threshold during the pedal release event, then the throttle valve position can consequently be adjusted independently of the operator's commands via the accelerator pedal (e.g., the one in...). Fig. The throttle position can be adjusted using the input device shown (130). In other words, during cylinder combustion, the throttle position can be adjusted based on input from the vehicle operator. However, during DFSO, the throttle cannot be adjusted based on input from the vehicle operator, but instead based on a difference between a target vehicle speed and an estimated actual and / or predicted vehicle speed.

[0061] By increasing the amount the throttle valve is open, the braking torque applied to the engine can be reduced. If the estimated vehicle speed decreases below the target vehicle speed, or if it is predicted that the estimated vehicle speed will fall below the target vehicle speed, the throttle valve can be opened to reduce the braking torque on the engine and thus decrease the amount of deceleration, thereby reducing the difference between the estimated and target vehicle speeds. In this way, excessive engine braking during DFSO can be reduced, and consequently, the vehicle speed can be maintained more accurately at a target level.

[0062] However, if it is not predicted that closing the throttle during DFSO will reduce the catalyst temperature below the threshold, but it is predicted that opening the throttle during DFSO will reduce the catalyst temperature below the threshold, then the throttle can be set to the closed position regardless of vehicle speed. Opening the throttle during DFSO can cause the catalyst temperature to drop below the threshold where it would not otherwise drop, because the temperature of the airflow through the engine may be significantly reduced during DFSO. In other words, opening the throttle during DFSO can cause a greater drop in catalyst temperature than would occur if the throttle were closed.Reducing the catalyst temperature below the threshold can decrease the catalyst's efficiency and increase emission levels. Consequently, in some examples, the throttle valve may only be opened during the DFSO if, during the DFSO, the vehicle speed is below the target speed or is expected to fall below the target speed, and either the catalyst temperature is not expected to fall below the threshold if the throttle valve is opened during the DFSO, or the catalyst temperature is expected to fall below the threshold even if the throttle valve is kept closed during the DFSO.In other examples, however, the throttle may be open during the DFSO as long as the vehicle speed is below the target speed or is expected to drop below the target speed. In still other examples, if it is not predicted that the catalytic converter will become saturated with oxygen during the pedal release event, then the throttle may be set to the closed position regardless of the vehicle speed. Opening the throttle during the DFSO can cause the catalytic converter to become saturated when it would not otherwise be saturated, because the airflow through the engine during the DFSO has a relatively high oxygen content due to the deactivation of cylinder combustion. Saturating the catalytic converter during the DFSO can cause the engine to run rich when the DFSO is exited in order to reduce the oxygen levels in the catalytic converter.Running the engine rich can reduce fuel efficiency. Consequently, in some examples, the throttle valve may only be open during DFSO if the vehicle speed is below the target speed, or is expected to fall below the target speed, and the catalyst is expected to become saturated. In still other examples, the throttle valve may only be open during DFSO if the vehicle speed is below the target speed, or is expected to fall below the target speed, the catalyst is expected to become saturated, and the catalyst temperature is expected to remain above the threshold with the throttle valve open.

[0063] It should be recognized that steps 316 and 318 may be optional and that in some examples, procedure 300 can be performed without performing steps 316 and 318. Consequently, in some examples, the throttle may be open during the DFSO as long as the estimated vehicle speed and / or engine speed are below the target vehicle speed and / or engine speed, or are expected to fall below the target vehicle speed and / or engine speed. The opening of the throttle itself during the DFSO may, in some examples, be performed regardless of the catalyst temperature and / or the oxygen storage levels in the catalyst.Therefore, in some examples, throttle valve adjustment during DFSO may not be based on catalyst temperature and / or oxygen storage levels in the exhaust catalyst. The throttle valve itself may be open during DFSO in response to vehicle speed and / or engine speed decreasing below the target speed or RPM trajectory, even if it is not predicted that oxygen storage levels will exceed the oxygen storage threshold and / or that catalyst temperatures will fall below the temperature threshold.

[0064] After opening the throttle valve at 322, the procedure 300 to 324 can continue, which involves adjusting the position of a camshaft (e.g., the one in Fig. 2 camshaft 328 shown) based on the engine speed and / or the throttle position and / or the mass airflow rate in the engine and / or the difference between the vehicle's target speed and the actual or estimated vehicle speed. The mass airflow rate can be based on the outputs from a mass airflow sensor (e.g., the one shown in Fig. 1 sensor 120 shown). Specifically, the intake camshaft can be adjusted if reduced engine braking is desired. In engine systems where one or more intake valves (e.g., the one in Fig. 1 inlet valve 52) is closed after a piston (e.g. the one in Fig. When the piston (36) has reached bottom dead center (BDC), adjusting the intake camshaft timing can involve retarding the camshaft timing, thus retarding the intake valve closing time. Consequently, the intake valve closing time can be set to a later point in the compression stroke, where the piston is further away from BDC. Closing the intake valve later in the compression stroke can reduce pumping work and therefore braking torque applied to the engine. In engine systems where one or more intake valves close before the piston reaches BDC, adjusting the intake camshaft position can involve advancing the intake valve closing time, thus causing the intake valve to close earlier in the intake stroke.Consequently, the intake valve closing time can be adjusted so that the intake valve closes at an earlier point in the intake stroke, where the piston is further away from UTP. By closing the intake valve at an earlier point in the intake stroke, the pumping work and therefore the braking torque exerted on the engine can be reduced. Then the process returns to 300.

[0065] Fig. Figure 4 shows an exemplary procedure for adjusting the position of a throttle plate (e.g., the one in Fig. (Throttle plate 64 shown in Figure 1) when exiting a DFSO mode. In some examples, the throttle plate may be set to a more open position during DFSO to reduce the braking torque to the engine and thereby decrease the rate at which the vehicle decelerates, as above regarding Fig. 3 has been explained. Consequently, in some examples during DFSO, the throttle adjustment may be controlled by input from a vehicle operator (e.g., the one in Fig. 1 operator shown 132) be independent. However, if the DFSO is left unattended during a pedal pressure event in which the operator is using a drive pedal (e.g., the one shown in Fig. When the input device 130 (shown) is depressed, the throttle valve adjustment becomes dependent on input from the vehicle operator. Specifically, in some examples, the increase in engine torque during a pedal pressure event may be sufficiently small that the ETC setpoint position may be a more closed position than the actual throttle valve position during DFSO. If fuel injection is activated and injected in an amount to match an air / fuel setpoint ratio at the current airflow through the engine, the supplied engine torque may be greater than the torque commanded by the operator. Method 400 can be performed to coordinate the control schemes for adjusting the throttle valve during DFSO and during cylinder combustion.

[0066] Procedure 400 begins at 402, which involves estimating and / or measuring the operating conditions of the engine. The operating conditions of the engine may include engine speed, a throttle position sensor output (e.g., the one in Fig. 1 sensor 58) estimated throttle position, a torque commanded by the operator which can be estimated based on the outputs from the input device position sensor, an oxygen storage level in an exhaust catalyst (e.g. the one in Fig. 1 exhaust catalyst 70), a fuel injection quantity, a measurement from an air mass flow sensor (e.g. the one in Fig. 1 sensor shown (120) contains certain inlet air mass flow, etc.

[0067] After estimating and / or measuring the operating conditions of the power machine at 402, the procedure 400 to 404 can continue, which includes determining whether a power machine (e.g., the one in ) Fig. The power machine shown (10) is located in a DFSO. Determining that the power machine is located in a DFSO can determine that a pedal release event has occurred, in a similar way to the one described above at 306. Fig. as described in section 3. However, in other examples, it can be determined that the power engine is located in a DFSO if one or more power engine cylinders (e.g., the one described in section 3) are included. Fig. 1 shown cylinder 30) no fuel is injected and cylinder combustion is deactivated.

[0068] If, at 404, it is determined that the engine is not in a DFSO, then procedure 400 to 406 can proceed, which involves adjusting the throttle position based on an ETC target position in the manner described above with respect to 304. Fig. The process described in section 3 is included. Then the procedure returns to step 400.

[0069] If, on the other hand, the engine is in a DFSO, procedure 400 can continue from 404 to 408, where at 408 it can be determined whether a pedal pressure event has occurred. The pedal pressure event can be the depressing of the accelerator pedal by the vehicle operator. In other examples, however, procedure 408 can additionally or alternatively include determining whether the DFSO has ended. Determining that the overrun cut-off mode has ended can be determined by one or more of the following events: the vehicle has stopped and an idle speed control mode has begun, and / or operator-requested torque has increased above a threshold. Consequently, procedure 400 at 408 can include determining whether operator-requested torque has increased.If no pedal pressure event has occurred and the accelerator pedal remains unpressed, so that a pedal release event continues, procedure 400 can proceed from 408 to 410, the procedure at 410 potentially including adjusting the throttle valve based on the estimated vehicle speed and / or the estimated oxygen storage level of the exhaust catalyst, as between 310-322 of procedure 300 in . Fig. 3 has been described. If the vehicle does not leave a DFSO, then the throttle valve can consequently be adjusted based on a difference between an estimated vehicle speed and a target vehicle speed and a predicted oxygen storage level in the exhaust catalyst, as described above. Fig. 3. Thus, in some examples, the method 400 at 410 may include performing the method 300 of Fig. 3. Then, the method returns to 400.

[0070] However, if a pedal pressure event is detected at 408 and / or the target torque increases above a threshold, procedure 400 to 412 may proceed, which may involve determining a target throttle position based on the pedal pressure applied by the vehicle operator. Consequently, procedure 408 may involve determining the target throttle position based on the amount of depressing / deflection of the accelerator pedal. As above regarding Fig. 3, the desired engine torque and the amount of throttle opening may increase with increasing deflection / increasing depression of the accelerator pedal.

[0071] After determining the throttle valve target position at 412, the procedure can continue from 400 to 414, which may include determining whether the throttle valve target position is a more closed position than the current throttle valve position. The current throttle valve position can be determined based on the outputs from a throttle valve position sensor (e.g., the one in Fig. 1). If the desired throttle position is a more closed throttle position than the current throttle position, then method 400 may proceed to 416 and decrease the throttle opening. Further, at 416, the method may include retarding spark timing and / or delaying fuel injection to the one or more engine cylinders to reduce excess torque output while decreasing the throttle position. Thus, at 416, method 400 may include not immediately injecting fuel in response to a pedal press event, but may include waiting a duration before injecting fuel if the desired throttle position is a more closed position than the current throttle position.The throttle position itself can be set to the target position at 416, but no fuel can be injected into the engine cylinders. In some examples, fuel injection can be delayed for a fixed duration. In other examples, however, the duration of the fuel injection delay can be proportional to the difference in throttle angle between the target throttle position and the actual throttle position, with the duration increasing as the difference in throttle angles increases. In still other examples, fuel injection can be delayed based on the mass airflow rate.

[0072] In other examples, fuel can be injected into the engine cylinders in response to the termination of the DFSO. Consequently, fuel injection cannot be delayed, but can instead be initiated in response to a pedal pressure event. In such examples, if the mass airflow to the engine cylinders is greater than desired, the spark timing can be retarded from a setpoint. In some examples, the setpoint can be the MBT. Consequently, Method 400 can involve initiating fuel injection and cylinder combustion when exiting the DFSO, and retarding the spark timing if the mass airflow is greater than desired when entering the DFSO, thus reducing excessive torque output from the engine.

[0073] The mass airflow to the engine cylinders can be estimated by the mass airflow sensor. A target mass airflow can be determined based on the target throttle position and a target air / fuel ratio. Consequently, procedure 400 at 416 may involve setting the throttle to the target position and waiting until the mass airflow reaches the target airflow before injecting fuel into the engine cylinders.

[0074] Then the procedure can continue from 416 to 418, which may include estimating the oxygen storage levels of the exhaust catalyst. The oxygen storage levels in the exhaust catalyst can be determined in a similar manner to that previously determined at 314. Fig. 3. Alternatively, if it is determined that the desired throttle position is not closed more than the current throttle position, method 400 may proceed to 418. In some examples, at 418, the method may additionally include adjusting the throttle to a desired position and injecting fuel based on the throttle angle and the desired air / fuel ratio.

[0075] After estimating the oxygen storage levels of the exhaust catalyst at 418, the procedure can continue from 400 to 420, which may include determining whether the oxygen storage levels are greater than a threshold. As above regarding 318 after Fig. As described in section 3, the threshold value can represent the oxygen levels in the catalyst at saturation, where essentially no additional oxygen can be stored in the catalyst. In other examples, however, the threshold value may be lower than the catalyst's saturation point, but still high enough that operating at a rich air / fuel ratio may be desirable.

[0076] If, at 420, the oxygen storage levels are greater than the threshold, the procedure can proceed from 400 to 422 and adjust the fuel injection quantity to operate at a rich air / fuel ratio. Consequently, at 422, in some examples, the procedure may involve injecting a quantity of fuel into one or more engine cylinders to achieve an air / fuel ratio less than stoichiometric (e.g., 14.7:1). The quantity of fuel to be injected at 422 may be estimated based on the throttle setpoint position, an estimated mass airflow through the engine, and the set air / fuel ratio. After the engine has operated rich at 422, the procedure can proceed from 400 to 424, which may involve resuming ETC and fuel delivery to maintain the torque commanded by the operator.Alternatively, if it is determined at 420 that oxygen storage levels are below the threshold, method 400 may proceed to 424. Consequently, the engine may not operate with a rich air / fuel mixture if oxygen storage levels are below the threshold.

[0077] The method may therefore include, at 424, adjusting the throttle based on the desired electronic throttle control position, which may be based on the torque commanded by the operator via the accelerator pedal. Further, the fuel injection amount may be estimated based on the operator-commanded torque, the ETC position, the mass air flow through the engine, and a desired air / fuel ratio, which may be approximately stoichiometric. Method 400 then returns.

[0078] Fig. Figure 5 shows a graphical representation 500, which illustrates the changes in the position of a throttle valve (e.g., the one in Fig. 1 throttle valve 62) shown during time in response to changes in the operating conditions of the engine of a power engine system, such as the power engine system according to Fig. Figure 1 illustrates this. Graphic 500 contains a target vehicle speed in graphic 502 and an actual estimated vehicle speed in graphic 503. The target vehicle speed can be set based on input from a vehicle operator (e.g., the person in Fig. 1 operator 132 of the vehicle) via an input device (e.g. the one shown in Fig. 1 input device 130 shown). During pedal releases, the target vehicle speed can be determined based on a lookup table stored in the controller's memory and can be a function of the expected pedal release duration. Furthermore, graphic 500 shows a specification of the fuel injection quantities in graphic 506 and the predicted oxygen storage levels of an exhaust catalyst (e.g., the one in Fig. The exhaust catalyst shown in Figure 70) is shown in graphical representation 508. The changes in the position of the throttle valve are shown in graphical representation 510.

[0079] The vehicle's target speed can be determined by the position of the input device, which is based on the outputs of a position sensor (e.g., the one in the Fig. The estimated vehicle speed can be determined by one or more sensors configured to measure vehicle speed, such as a wheel speed sensor or a transmission output speed sensor. The fuel injection quantity can be determined by a controller (e.g., the one shown in 134), which is configured to measure the position of the input device. Fig. 1 shown controller 12) be the quantity of fuel commanded to be delivered to one or more engine cylinders (e.g. the one in Fig. 1). The predicted oxygen storage levels of the exhaust catalyst may be determined based on the current oxygen storage levels and the engine operating conditions in a manner similar to that described above with respect to 314 and 316. Fig. 3. The position of the throttle valve can be adjusted between a fully closed first position and a fully open second position, as described above with respect to Fig. 3 has been described. The position of the throttle valve can be determined by a throttle valve position sensor (e.g., the one described in 3). Fig. 1). Furthermore, the position of the throttle valve can be adjusted by a throttle valve actuator based on the signals received from the controller.

[0080] Starting at time t0, the target vehicle speed (graphic 502) and the estimated vehicle speed (graphic 503) may be approximately the same and may be at relatively low levels. The pedal position may not be depressed at t0 (graphic 504), and therefore a pedal release state may be present at t0. Fuel injection may be switched off at t0 (graphic 506), and the engine may be in a DFSO (Dead Fuel Storage Oscillation). The predicted oxygen storage level may fluctuate around a lower first level, O1. Because cylinder combustion is deactivated at t0, the throttle position may be set to the fully closed first position.

[0081] Between times t0 and t1, the target vehicle speed and the estimated vehicle speed may remain approximately the same, although they may continue to fluctuate at relatively low levels. The pedal position may not be depressed, and therefore the pedal release state may persist. Fuel injection may remain off, and the engine may be in DFSO (Deep Fuel Storage). The predicted oxygen storage level may fluctuate around the lower first level, O1. Because cylinder combustion is deactivated, the throttle position may be set to the fully closed first position.

[0082] At time t1, a pedal pressure event can occur, whereby an operator of the vehicle can depress the accelerator pedal. The vehicle's target speed can increase at t1. In response to the increase in torque commanded by the operator at t1, the throttle valve can be set to a more open position and fuel injection can be activated. Due to the commencement of cylinder combustion at t1, the predicted oxygen storage levels can begin to decrease.

[0083] Between time points t1 and t2, the pedal position may remain depressed, and the vehicle speed may continue to increase. In response to the increase in the target vehicle speed, the throttle position may remain open, allowing fuel to continue being injected into the engine cylinders. The throttle position and the amount of fuel injected into the engine cylinders may be based on a target air / fuel ratio and the target vehicle speed. The predicted oxygen storage levels may continue to fluctuate around the same levels as at t1 because the engine may alternate between slightly lean and slightly rich operation to increase the oxidation and reduction reactions of pollutants at the catalyst.

[0084] At time t2, a pedal release event may occur, allowing the vehicle operator to stop depressing the accelerator pedal. Consequently, the torque applied by the operator may decrease below a threshold at t2, at which point the engine may enter a DFSO (Deep Fuel Storage). Fuel injection may be shut off at t2. Furthermore, the throttle valve may be set to the closed first position at t2 in response to the onset of the DFSO. The predicted oxygen storage levels may begin to increase at t2 because the vehicle speed is relatively high at t2. Because the vehicle speed is sufficiently high at t2, it can therefore be predicted that the duration of the DFSO event may be long enough to cause an increase in the catalyst's oxygen storage levels.

[0085] Between times t2 and t3, the desired vehicle speed may continue to decrease. Consequently, upon entering DFSO at t2, the desired vehicle speed may be based on a desired speed trajectory that may be stored in the controller's memory. As such, the desired speed may be based on a desired deceleration rate during DFSO between t2 and t3. However, between t2 and t3, the estimated vehicle speed may decrease faster than the desired speed trajectory. Stated another way, the actual vehicle speed may be less than desired. Consequently, the engine may decelerate more than desired. The predicted catalyst oxygen storage levels may continue to increase between t2 and t3. However, because the oxygen storage levels have not reached a threshold level, O2, as in Fig. As shown in Figure 5, the throttle valve can remain closed between t2 and t3. The threshold level, O2, can represent the saturation point of the catalyst, beyond which essentially no additional oxygen can be absorbed by the catalyst.

[0086] At time t3, the predicted oxygen levels can reach the threshold, O2. In response to the vehicle speed being below the target vehicle speed at t3, and the predicted oxygen levels reaching the threshold, the throttle valve can be set to the open second position at t3. Opening the throttle valve can allow more oxygen to flow through the engine, thus allowing the predicted oxygen storage level to remain approximately at the threshold, which can be the catalyst saturation point, as long as the throttle valve is open during the DFSO. Consequently, opening the throttle valve during the DFSO can saturate the catalyst. Fuel injection can remain off, and the target vehicle speed can continue to decrease during the DFSO according to the target speed trajectory. The pedal position can remain in a pedal-release position.

[0087] Between times t3 and t4, the engine may remain in DFSO; fuel injection may be off, and the pedal position may be in a non-depressed position. The target vehicle speed may still remain higher than the estimated vehicle speed, although the difference may decrease due to the throttle opening at t3. The predicted oxygen levels may remain at approximately O2, with the throttle remaining open.

[0088] At time t4, due to the opening of the throttle valve, the estimated vehicle speed and the vehicle's target speed may continue to decrease, and the difference between them may also continue to decrease. The throttle valve may remain in the open position. Furthermore, the catalytic converter may remain relatively saturated at t4. The accelerator pedal may still be in the same position as between t3 and t4, and fuel injection may remain off.

[0089] Between times t4 and t5, the desired vehicle speed may continue to decrease because the pedal position remains at a pedal-release position, fuel injection remains off, and the engine remains in DFSO. The estimated vehicle speed may begin to match the desired vehicle speed, and the throttle position may be maintained at relatively the same position as at t4. Oxygen storage levels can still be predicted to remain at approximately O2.

[0090] At time t5, a pedal pressure event can occur, similar to t1. In response to this event, the target vehicle speed can increase, and fuel injection can be activated. Because the throttle valve is already in the open position at t5, fuel injection can be activated at a higher level F1, and the vehicle speed may be approximately equal to the target vehicle speed. At t1, the increase in vehicle speed from the target vehicle speed was delayed because it can take some time for the airflow through the engine to increase to a rate at which the supplied engine torque equals the engine torque. However, because the throttle valve is already in the open position at t5, the airflow through the engine is greater at t5 than at t1.The engine itself can react more quickly to increases in the requested vehicle speed. The predicted oxygen storage levels may decrease at t5, as the oxygen levels in the exhaust gas may decrease due to the start of cylinder combustion.

[0091] Between times t5 and t6, the pedal position may continue to be depressed, and as such, the vehicle speed may continue to increase. In response to the increase in desired vehicle speed, the throttle position may be held open, and fuel may continue to be injected into the engine cylinders. The throttle position and the amount of fuel injected into the engine cylinders may be based on a desired air / fuel ratio and the desired vehicle speed. Predicted oxygen storage levels may continue to fluctuate and / or decrease because the engine may cycle between slightly lean and slightly rich operation to enhance pollutant oxidation and reduction reactions at the catalyst.

[0092] At time t6, a pedal release event may occur, allowing the vehicle operator to stop depressing the accelerator pedal. Consequently, the torque applied by the operator may decrease below a threshold at t6, at which point the engine may enter a DFSO (Deep Fuel Storage). Fuel injection may be shut off at t6. Furthermore, the throttle valve may be adjusted to the closed first position at t6 in response to the onset of the DFSO. The predicted oxygen storage levels may begin to increase at t6 because the vehicle speed is relatively high at t6. Because the vehicle speed is sufficiently high at t6, it can therefore be predicted that the duration of the DFSO event may be long enough to cause an increase in the catalyst's oxygen storage levels.

[0093] Between times t6 and t7, the target vehicle speed may continue to decrease. Consequently, upon entering the DFSO at t6, the target vehicle speed may be based on a target speed trajectory that may be stored in the controller's memory. The target speed itself may be based on a target deceleration rate during the DFSO between t6 and t7. However, between t6 and t7, the estimated vehicle speed may be approximately the same as the target speed trajectory. Even if the predicted catalyst oxygen storage levels continue to increase between t6 and t7 and reach the threshold value, O2, the throttle may remain closed between t6 and t7 because the estimated vehicle speed is essentially the same as the target vehicle speed. Because the vehicle is not decelerating more than desired, the throttle may not open.Opening the throttle valve may cause the vehicle speed to exceed the target speed due to reduced braking torque. Between t6 and t7, the pedal position may remain at the pedal release position and fuel injection may remain off.

[0094] At time t7, a pedal pressure event may occur, where an operator of the vehicle may depress the accelerator pedal. The vehicle's target speed may increase at t7. In response to the increase in torque commanded by the operator at t7, the throttle valve may be set to a wider open position, and fuel injection may be activated. Due to the commencement of cylinder combustion at t7, the predicted oxygen storage levels may begin to decrease.

[0095] Between times t7 and t8, the pedal position may remain depressed, and the vehicle speed may continue to increase. In response to the increase in the target vehicle speed, the throttle position may remain open, and fuel may continue to be injected into the engine cylinders. The throttle position and the amount of fuel injected into the engine cylinders may be based on a target air / fuel ratio and the target vehicle speed. The predicted oxygen storage levels may continue to decrease until they reach levels similar to those at t1 because the engine may alternate between slightly lean and slightly rich operation to enhance the oxidation and reduction reactions of pollutants at the catalyst.

[0096] At time t8, a pedal release event may occur, whereby the vehicle operator may stop depressing the accelerator pedal. Consequently, at t8, the operator-commanded torque may decrease below a threshold, whereby the engine may enter DFSO. As such, fuel injection may be shut off at t8. Furthermore, at t8, the throttle may be adjusted to the closed first position in response to the onset of DFSO. The predicted oxygen storage levels may begin to increase at t8 because the vehicle speed is relatively high at t8. Consequently, because the vehicle speed is sufficiently high at t8, it can be predicted that the duration of the DFSO event may be long enough to cause an increase in the catalyst's oxygen storage levels.

[0097] Between times t8 and t9, the target vehicle speed may continue to decrease. Consequently, upon entering the DFSO at t8, the target vehicle speed may be based on a target speed trajectory that may be stored in the controller's memory. The target speed itself between t8 and t9 may be based on a target deceleration rate during the DFSO. However, between t8 and t9, the estimated vehicle speed may decrease faster than the target speed trajectory. In other words, the actual vehicle speed may be lower than desired. Consequently, the engine may decelerate more than desired. The predicted catalyst oxygen storage levels may continue to increase between t8 and t9, but they may not reach the threshold, O2, during the pedal release event. Because the oxygen storage levels are not predicted to reach the threshold, O2, as in Fig. As shown in Figure 5, the throttle valve can remain closed between t8 and t9, even if the vehicle speed may be less than the trajectory of the vehicle's target speed.

[0098] However, at time t9, a pedal-press event may occur, whereby the vehicle operator may depress the accelerator pedal. As such, the desired vehicle speed may increase at t9. In response to the increase in operator-commanded torque at t9, the throttle may be adjusted to a wider open position and fuel injection may be turned on. Due to the onset of cylinder combustion at t9, the predicted oxygen storage levels may begin to decrease.

[0099] Between times t9 and t 10The accelerator pedal position can remain depressed, and the vehicle speed can continue to increase. In response to the increase in the target vehicle speed, the throttle position can remain open, allowing fuel to continue being injected into the engine cylinders. The throttle position and the amount of fuel injected into the engine cylinders can be based on a target air / fuel ratio and the target vehicle speed. The predicted oxygen storage levels can continue to decrease until they reach levels similar to those at t1 because the engine can alternate between slightly lean and slightly rich operation to increase the oxidation and reduction reactions of pollutants at the catalyst.

[0100] At time t 10A pedal release event can occur, allowing the vehicle operator to stop depressing the accelerator pedal. Consequently, t 10 The torque ordered by the operator may drop below a threshold, at which point the engine may enter a DFSO (Dead Fuel Suppression). The fuel injection itself can lead to... 10 can be switched off. Furthermore, the throttle valve can be closed in response to the start of the DFSO. 10 to be set to the closed first position. The predicted oxygen storage levels can be adjusted to t 10 begin to rise because the vehicle speed is increasing. 10 is relatively high. Because the vehicle speed is at t 10 If the DFSO level is sufficiently high, it can therefore be predicted that the duration of the DFSO event may be long enough to cause an increase in the oxygen storage levels of the catalyst.

[0101] Between times t 10 and t11 The vehicle's target speed may continue to decrease. Consequently, upon entering the DFSO, the speed may increase to t. 10 The vehicle's target speed is based on a target speed trajectory that can be stored in the controller's memory. The target speed between t 10 and t 11 As such, it can be based on a target delay rate during the DFSO. Between t 10 and t 11 However, the estimated vehicle speed may decrease faster than the target speed trajectory. In other words, the actual vehicle speed may be lower than desired. Consequently, the engine may decelerate more than desired. The predicted oxygen storage levels of the catalyst may vary between t 10 and t 11 continue to increase. However, because the oxygen storage levels have not reached a threshold level, O2, as in Fig. As shown in section 5, the throttle valve can be adjusted between t 10 and t 11 Remain closed.

[0102] At time t 11 The predicted oxygen levels can reach the threshold, O2, in response to the vehicle speed, which changes to t 11 below the vehicle's target speed, and the predicted oxygen levels reaching the threshold, the throttle valve to t 11The throttle valve can be set to the open second position. Opening the throttle valve can allow more oxygen to flow through the engine, thus keeping the predicted oxygen storage level approximately at the threshold, which may be the catalyst saturation point, as long as the throttle valve is open during the DFSO. Consequently, opening the throttle valve during the DFSO can saturate the catalyst. Fuel injection can remain off, and the vehicle's target speed can continue to decrease during the DFSO according to the target speed trajectory, thereby prolonging the DFSO event and improving fuel economy. The pedal position can remain in a pedal-release position.

[0103] Between times t 11 and t 12The engine may remain in DFSO; fuel injection may be off, and the pedal position may be in a non-depressed position. The desired vehicle speed may still remain higher than the estimated vehicle speed, but the difference may be due to the throttle opening. 11 can decrease. Between t 11 and t 12 However, the throttle position can be adjusted based on the amount of difference between the target vehicle speed and the estimated vehicle speed. If the difference between the target vehicle speed and the estimated vehicle speed is between t 11 and t 12As the oxygen level continues to decrease, the throttle valve can therefore be adjusted proportionally to a further closed position, but not to the fully closed initial position. The predicted oxygen levels can remain at approximately O2, with the throttle valve remaining open.

[0104] At time t 12 A pedal pressure event can occur, and an operator of the vehicle can depress the accelerator pedal. The vehicle's target speed as such can be reduced. 12 The target increase in vehicle speed may, however, be less than the increase in vehicle speed resulting from injecting a quantity of fuel according to the current position of the throttle valve at t. 12 and would result in the target air / fuel ratio. Because the throttle valve is open between t during the DFSO event. 11 and t 12 Since it was open, the throttle valve position could therefore be between t 11 and t12 a wider open position than the throttle target position, which corresponds to the torque commanded by the operator, which is determined by the pedal position. 12 This has been proven. Consequently, t can be... 12 The throttle valve position can be adjusted to a more closed position, which may be the throttle valve target position, which can cause an increase in vehicle speed corresponding to the target increase in vehicle speed according to the amount of pedal pressure applied to the pedal. 12 Consequently, the fuel injection can be adjusted to t 12 remain off to prevent an excessive torque situation. As such, the predicted oxygen storage level can remain approximately at the threshold, O2.

[0105] Between times t 12 and t 13 fuel injection can remain off until the air mass flow rates between t 12and t 13 are reduced to a steady level according to the position of the throttle valve. Consequently, the throttle valve can be adjusted between t 12 and t 13 at the same target position as at t 12 be maintained. Due to the fact that fuel combustion between t 12 and t 13 If the vehicle has not started, the estimated vehicle speed may be lower than the intended vehicle speed. The pedal may be t 12 and t 13 They may remain depressed. Furthermore, the predicted oxygen storage levels may remain at the threshold, O2.

[0106] While in the Fig. 5 shown example between t 12 and t 13While the start of fuel injection may be delayed when exiting DFSO, it is important to note that in other examples, fuel injection may be initiated in response to a pedal pressure event regardless of the current air flow to the engine. Consequently, if the throttle is in an open position during DFSO, fuel injection may be initiated when exiting DFSO in response to a pedal pressure event (e.g., depressing an accelerator pedal) and may not be delayed. In such examples, spark retard and / or cam timing may be adjusted to reduce torque output when exiting DFSO.If the torque output is greater than desired when fuel injection is activated in response to a pedal pressure event, the spark timing and / or cam timing can consequently be retarded to reduce the torque output to the target level.

[0107] At time t 13 the air mass flow rate can reach the target rate according to the position of the pedal and the target vehicle speed, with the fuel injection as such to t 13 The predicted oxygen storage levels may therefore begin to decrease. The pedal may remain depressed, and the vehicle speed may continue to increase; however, due to the start of cylinder combustion, the estimated vehicle speed may also begin to increase.

[0108] After time t 13The pedal position may continue to be depressed, and the vehicle speed itself may continue to increase. In response to the increase in the desired vehicle speed, the throttle position may be held open, and fuel may continue to be injected into the engine cylinders. The throttle position and the amount of fuel injected into the engine cylinders may be based on a desired air / fuel ratio and the desired vehicle speed. Predicted oxygen storage levels may continue to decrease.

[0109] In this way, excessive engine braking during a DFSO can be reduced. Specifically, opening the throttle during a DFSO can reduce the braking torque exerted on the engine. As such, opening the throttle when the vehicle speed drops below the target speed trajectory, or when it is anticipated that the vehicle speed will drop below the target speed trajectory, achieves the technical effect of more accurately matching the actual estimated vehicle speed to the target speed trajectory during the DFSO. Furthermore, keeping the throttle open during a DFSO allows the air mass flow rates through the engine to be maintained at relatively high levels.

[0110] In this way, the increase in operator-commanded torque can be met more quickly by the engine when DFSO is exited due to a pedal pressure event by a vehicle operator. Consequently, by maintaining the throttle in an open position during DFSO, a second technical effect of increasing the engine's responsiveness to increases in driver-requested torque is achieved. If the throttle is closed during DFSO, then the throttle can be opened when DFSO is exited to cause a corresponding increase in engine torque requested by the vehicle operator. However, it may take a period of time for the mass air flow to increase to levels sufficient to cause the driver-requested torque.Consequently, there can be a delay between the actual applied engine torque and the engine's target torque. However, by maintaining the throttle position open during the DFSO, the increases in driver-requested torque upon exiting the DFSO can be achieved more quickly than in approaches where the throttle is closed during the DFSO.

[0111] In this way, the engine's responsiveness can be increased without compromising fuel economy. Fuel injection can remain switched off during DFSO, although the throttle position can remain open. This allows for a more precise and rapid response to torque demands without sacrificing fuel efficiency.

[0112] In one description, a method may include controlling the position of a throttle valve in an air intake of a power engine that propels a vehicle, in response to commands from a vehicle operator, and, during a fuel cut-off mode, increasing the throttle valve opening independently of the operator's commands when the vehicle's speed is below a target speed or target speed trajectory, or is expected to fall below a target speed or target speed trajectory. In some examples, the method may further include decreasing the throttle valve opening if the vehicle speed increases above the target speed or target speed trajectory during the fuel cut-off mode.The target speed trajectory can be stored in non-volatile memory of a vehicle controller, whereby the target vehicle speed trajectory can be determined based on an initial vehicle speed at the start of DFSO mode and / or an expected duration of DFSO mode. In some examples, the method can further include increasing the throttle opening in response to a determination that the temperature of a catalyst coupled to an engine exhaust remains above a threshold during fuel cut-off mode. Additionally or alternatively, the method can include setting the throttle to a closed position when entering DFSO mode and subsequently increasing the throttle opening during DFSO mode.In some examples, the engine may be a four-stroke engine, and increasing the throttle opening may slow the rate of deceleration to prolong operation in the fuel cut-off mode. The increase in throttle opening may be based on a difference between the vehicle's target speed and its actual speed, with the amount of the throttle opening increase increasing with each increase in this difference. The fuel cut-off mode may end upon one or more of the following events: the engine speed has dropped below a threshold and an idle speed control mode begins; or the operator commands an increase in power.In further examples, the procedure may include initiating fuel injection when the fuel cut-off mode ends and retarding a spark timing control in response to engine torque exceeding a setpoint level, where the setpoint level can be determined based on commands from the vehicle operator. In some examples, camshaft timing may be adjusted during fuel cut-off mode via a variable cam timing (VCT) system, allowing the closing point of an intake valve in a combustion cylinder of the engine to be set to a later point in a piston's compression stroke within that cylinder.Alternatively, the camshaft timing during fuel cut-off mode can be adjusted via a variable cam timing (VCT) system, thus setting the closing point of an intake valve in a combustion cylinder of the engine to an earlier point in the intake stroke of a piston in that cylinder. The target speed trajectory can be based on the vehicle's speed at the onset of fuel cut-off and a target deceleration rate.

[0113] In another embodiment, a method may include controlling the position of a throttle valve in an air intake of a power engine that propels a vehicle in response to commands from a vehicle operator; and, during a fuel cut-off mode, increasing the throttle valve opening independently of the operator's commands in response to a signal that the temperature of a catalyst coupled to an exhaust of the power engine remains above a threshold during the fuel cut-off mode. The method may further include closing the throttle valve opening in response to the vehicle's speed increasing above the target speed trajectory.The method may additionally or alternatively include maintaining the throttle position during fuel cut-off in response to the vehicle's speed reaching the target speed trajectory. The method may additionally or alternatively include initially closing the throttle at the start of the fuel cut-off mode to extend the time before the catalyst temperature reaches the threshold. In some examples, the method may additionally or alternatively include determining, based on a catalyst temperature at the start of the fuel cut-off mode and / or a throttle position and / or an estimated pedal release duration, whether the catalyst temperature reaches the threshold during the fuel cut-off mode.The vehicle operator's commands may include input from the vehicle operator via an accelerator pedal. In some examples, the procedure for exiting fuel cut-off mode may additionally include not injecting fuel into the engine cylinders if the air mass flow rate in the engine is greater than a target air mass flow rate, where the target air mass flow rate can be determined based on the vehicle operator's commands and a target air / fuel ratio.In other examples, the procedure upon exiting the fuel cut-off mode may include injecting fuel into the cylinders of the engine and, in response to the mass airflow rate in the engine being greater than a set mass airflow rate, retarding a spark timing control from a setpoint, the set mass airflow rate being determined based on the commands of the vehicle operator and a set air / fuel ratio.

[0114] In another representation, a system may include a four-stroke internal combustion engine, a throttle valve positioned in an engine inlet of the engine to control the airflow to the engine cylinders of the engine, an input device configured to produce an output corresponding to a torque commanded by an operator, and a controller with computer-readable instructions.The computer-readable instructions may include instructions to: increase the throttle opening during a fuel cut-off mode, irrespective of the torque commanded by the operator, in response to an indication that a vehicle speed is below a target speed trajectory or is expected to fall below a target speed trajectory; and otherwise, to control the position of a throttle valve in relation to the torque commanded by the operator.In some examples, the system may further include a three-way exhaust catalyst, wherein the catalyst may be configured to temporarily store oxygen, and wherein the computer-readable instructions further include instructions to reduce the throttle opening during fuel cut-off mode when the catalyst's oxygen storage capacity is predicted to fall below a threshold. In some examples, the computer-readable instructions may further include instructions to delay fuel injection into the engine cylinders when fuel cut-off mode is exited if the air mass flow rate in the engine is greater than a target air mass flow rate.

[0115] It should be noted that the example control and estimation routines included herein may be used with various engine and / or vehicle system configurations. The control methods and routines disclosed herein may be stored as executable instructions in non-transitory memory and may be executed by the control system, including the controller, in combination with the various sensors, actuators, and other engine hardware. The specific routines described herein may represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, and the like. As such, the various acts, operations, and / or functions illustrated may be performed in the illustrated order, executed in parallel, or in some cases, omitted.Likewise, the order of processing is not necessarily required to achieve the features and advantages of the exemplary embodiments described herein, but is provided for ease of illustration and description. One or more of the illustrated acts, operations, and / or functions may be performed repeatedly depending on the particular strategy employed. Further, the described acts, operations, and / or functions may graphically represent code to be programmed into the non-transitory memory of the computer-readable storage medium in the engine control system, wherein the described acts are performed by executing the instructions in a system including the various components of the engine hardware in combination with the electronic controller.

[0116] It is clear that the configurations and routines disclosed herein are exemplary and that these specific embodiments are not to be considered limiting, as numerous variations are possible. The above technique can be applied, for example, to V-6, I-4, I-6, V-12, Boxer-4, and other types of power engines. The subject matter of this disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations and other features, functions, and / or properties disclosed herein.

[0117] The following claims particularly set forth certain combinations and subcombinations that are considered novel and non-obvious. These claims may refer to "a" element or "a first" element, or its equivalent. Such claims should be understood to include the inclusion of one or more such elements and neither require nor exclude two or more such elements. Further combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed by amending the present claims or by presenting new claims in this or a related application.Such claims, whether broader in scope than, narrower than, equal to, or different in scope from the original claims, are also considered to be included within the subject matter of the present disclosure.

Claims

[1] Procedure comprising: Controlling a position of a throttle valve in an air intake of an engine, which drives a vehicle, in relation to the commands of an operator of the vehicle; and during a fuel cut-off (DFSO) mode, adjusting a throttle opening independently of operator commands to maintain a vehicle speed at a desired speed or a desired speed trajectory, wherein the adjusting comprises increasing the throttle opening if the vehicle speed is below a desired speed or a desired speed trajectory or is expected to fall below a desired speed or a desired speed trajectory, and decreasing the throttle opening if the vehicle speed increases above the desired speed or the desired speed trajectory or is expected to increase above the desired speed or the desired speed trajectory during the fuel cut-off mode; and when the fuel cut-off mode ends and fuel injection resumes: retarding a spark timing in response to an air mass flow rate that exceeds a target air mass flow rate, where the target air mass flow rate is determined based on the commands of the vehicle operator. [2] The method of claim 1, further comprising increasing the opening of the throttle valve in response to a determination that a temperature of a catalyst coupled to an exhaust of the engine remains above a threshold during the fuel cut mode. [3] The method of claim 1, further comprising setting the throttle to a closed position when entering the DFSO mode and then increasing the opening of the throttle during the DFSO mode. [4] The method of claim 1, wherein the engine comprises a four-stroke engine and increasing the throttle opening reduces engine braking and therefore slows a rate of deceleration to prolong operation in the fuel cut mode. [5] The method of claim 1, wherein increasing the throttle opening is based on a difference between the desired vehicle speed and the vehicle speed, and wherein an amount of increase in the throttle opening increases for increases in the difference between the desired vehicle speed and the vehicle speed. [6] The method of claim 1, wherein the fuel cut mode ends upon one or more of the following events: the engine speed has decreased below a threshold and an idle speed control mode begins; or the operator commands an increase in power. [7] The method of claim 1, further comprising adjusting camshaft timing during the fuel cut mode via a variable cam timing (VCT) system such that a closing timing of an intake valve of a combustion cylinder of the engine is adjusted to a later point in a compression stroke of a piston in the cylinder. [8] The method of claim 1, further comprising adjusting camshaft timing during the fuel cut mode via a variable cam timing (VCT) system such that a closing timing of an intake valve of a combustion cylinder of the engine is adjusted to an earlier point in an intake stroke of a piston in the cylinder. [9] The method of claim 1, wherein the desired speed trajectory is based on the speed of the vehicle at an initiation of the overrun fuel cut and an estimated pedal release duration. [10] Procedure comprising: Controlling a position of a throttle valve in an air intake of an engine, which drives a vehicle, in relation to the commands of an operator of the vehicle; and during a fuel cut-off mode, increasing a throttle opening independently of operator commands in response to an indication that a temperature of a catalyst coupled to an exhaust of the engine remains above a threshold during the fuel cut-off mode with the throttle open; and upon exiting the fuel cut-off mode, injecting fuel into the cylinders of the engine and, in response to an air mass flow rate in the engine being greater than a desired air mass flow rate due to the increased throttle opening, retarding a spark timing from a desired value, wherein the desired air mass flow rate is determined based on the vehicle operator's commands and a desired air / fuel ratio. [11] The method of claim 10, further comprising: closing the throttle opening in response to the speed of the vehicle increasing over a desired speed trajectory. [12] The method of claim 10, further comprising initially closing the throttle at the initiation of the overrun fuel cut mode to extend the period of time before the temperature of the catalyst reaches the threshold. [13] The method of claim 12, further comprising determining whether the temperature of the catalyst reaches the threshold during the fuel cut-off mode based on at least one of a temperature of the catalyst at the start of the fuel cut-off mode and a position of the throttle valve and an estimated pedal release duration. [14] The method of claim 10, further comprising, upon exiting the fuel cut-off mode, not injecting fuel into the cylinders of the engine when a mass air flow rate in the engine is greater than a desired mass air flow rate, the desired mass air flow rate being determined based on the commands of the vehicle operator and a desired air / fuel ratio. [15] System comprising: a four-stroke internal combustion engine; a throttle valve positioned in an engine intake of the engine for regulating air flow to the engine cylinders of the engine; an input device configured to generate an output corresponding to a torque commanded by an operator; and a controller with computer-readable instructions to: during a fuel cut-off mode, increasing a throttle opening independent of the operator commanded torque in response to an indication that a vehicle speed is below a desired speed trajectory or that a vehicle speed is expected to fall below a desired speed trajectory; and otherwise Controlling the position of a throttle valve in relation to the torque commanded by the operator; and Delaying fuel injection into the engine cylinders when exiting the fuel cut-off mode when a Air mass flow rate in the engine is greater than a target air mass flow rate. [16] The system of claim 15, further comprising a three-way exhaust catalyst, the catalyst configured to temporarily store oxygen, and the computer readable instructions further include instructions for decreasing the throttle opening during the fuel cut mode when the oxygen storage capacity of the catalyst is predicted to fall below a threshold.

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