System and method for engine poppet valve diagnostics

Abstract

The present disclosure provides "Systems and methods for engine poppet valve diagnostics". Systems and methods for determining operation of a cylinder deactivation / restart device are disclosed. In one example, a hot engine is rotated without fuel being supplied to determine the presence or absence of a deteriorated valve driver. A deteriorated valve driver can be determined when there is no temperature increase in the engine exhaust system.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of vehicle engines, and more particularly to engine lifter diagnostics. BACKGROUND

[0002] Intake and exhaust lift valves of an engine cylinder can be selectively deactivated to conserve fuel. Intake and exhaust valves can be selectively activated and deactivated via electromechanical actuators that can from time to time place the valves in a deactivated state. On the other hand, the electromechanical actuators can allow the intake and exhaust valves to continue to operate even if the intake and exhaust valves are commanded to the deactivated state. If the intake and exhaust valves continue to operate when the valve actuators are commanded to deactivate the valves, fresh air can be pumped into the exhaust system of the engine, where it can affect catalyst activity, thereby degrading vehicle emissions. Conversely, if the valves continue to be deactivated after the valve actuators are commanded to activate the valves, the engine can produce less power than expected, and fuel can accumulate in the cylinders whose valves remain deactivated.

[0003] One way to determine whether the valve actuators are activating and deactivating the intake and exhaust lift valves can be to measure cylinder pressure during a cycle of the cylinder. Alternatively, sensors can be provided to sense the position of the valve actuators to determine whether the valve actuators are reaching their commanded positions. However, cylinder pressure sensors and valve actuator position sensors can significantly increase the cost of the system. Thus, it can be desirable to provide a way to determine whether the intake and exhaust valve actuators are performing as expected without deploying cylinder pressure sensors or valve actuator position sensors. SUMMARY

[0004] The inventors herein have recognized the above problems and have developed an engine operating method comprising: causing, via a controller, an engine to rotate without combusting fuel; indicating, in response to a lack of a temperature increase in an exhaust system, a deterioration of a valve actuator after commanding activation of lift valves of one or more engine cylinders while causing the engine to rotate without combusting fuel; and adjusting operation of the engine in response to the indication of the deterioration of the valve actuator.

[0005] By sampling the temperature of the gases flowing through the exhaust system, it is possible to provide a technical effect that determines whether the intake and exhaust valve drivers are operating as expected. In one example, after combustion has ceased in the engine, hot exhaust gases can be trapped in one or more of the engine cylinders. At the same time, the intake and exhaust valves of other engine cylinders can be operated according to a four-stroke engine cycle. With no combustion occurring within the engine, the engine can be rotated by an electric motor such that air flowing through the cylinders with operating intake and exhaust valves cools the gases flowing through the exhaust system. After the temperature of the gases in the exhaust system has been reduced, the trapped hot exhaust gases in the cylinders with deactivated valves can then be released into the exhaust system by commanding the activation of the previously deactivated intake and exhaust valves. If the temperature in the exhaust system increases, it can be determined that the intake and exhaust valve drivers are operating as expected. However, if the temperature in the exhaust system does not increase, it can be determined that the intake and exhaust valve actuators are not operating as expected because it can be inferred that the exhaust is still trapped in the engine cylinders or that fresh air is unable to enter the cylinders and participate in combustion.

[0006] The present specification can provide several advantages. In particular, the method can provide improved diagnosis of engine cylinder valve deactivation devices and intake and exhaust valves. Additionally, the method can provide cylinder diagnosis without increasing system cost. Furthermore, the method can reduce engine emissions if a deteriorated valve actuator is detected.

[0007] It is understood that the above summary is provided to introduce selected concepts in a simplified form, and is not intended to identify key or essential features of the claimed subject matter nor is it intended to limit the scope of the claimed subject matter to any particular implementations described in the above summary. Furthermore, the claimed subject matter is not limited to implementations that solve any or all of the disadvantages of any of the problems presented in the above background. BRIEF DESCRIPTION OF DRAWINGS

[0008] Figure 1 A schematic diagram of one cylinder of an example engine system is shown;

[0009] Figure 2 An example cylinder valve activation / deactivation device is shown;

[0010] Figures 3A-3B An example engine cylinder configuration for an engine is shown; Figure 1

[0011] Figure 4 and Figure 5 A diagnostic sequence for an example cylinder valve deactivation mechanism is shown; and

[0012] Figure 6 and​Figure 7 An example method for operating the engine is shown. Detailed Implementation

[0013] This specification relates to the operation of diagnosing an engine that includes a drive mechanism for cylinder lift valves (e.g., intake and exhaust valves). The drive mechanism may be included in the engine to selectively deactivate and activate the intake and exhaust valves of engine cylinders, thereby enabling and disabling engine cylinder modes. Figure 2 An example drive mechanism for cylinder valves is shown in the figure. Figure 3A and Figure 3B Two example engine cylinder configurations are shown in the figure. Figure 4 and Figure 5 The diagram shows the sequence used to determine the presence or absence of valve and valve actuator degradation. Figure 6 and Figure 7 This method can be used to diagnose the presence or absence of valve and valve actuator deterioration.

[0014] refer to Figure 1 An internal combustion engine 10 is controlled by an electronic engine controller 12. The internal combustion engine 10 includes a plurality of cylinders, one of which is shown in... Figure 1 In the middle. Controller 12 from Figure 1 Various sensors in the system receive signals and employ... Figure 1 Various actuators adjust engine operation based on received signals and instructions stored in the controller's memory. For example, if the controller 12 detects deterioration of the cylinder lift valve or its actuator, the controller 12 can limit engine torque production by restricting the amount of air and fuel delivered to the engine.

[0015] Engine 10 includes a cylinder head 35 and a cylinder block 33, which include a combustion chamber 30 and cylinder walls 32. A piston 36 is positioned in the combustion chamber and reciprocates via a connection to a crankshaft 40. A flywheel 97 and a ring gear 99 are connected to the crankshaft 40. A starter 96 (e.g., a low-voltage (operating at less than 30 volts) motor) includes a pinion shaft 98 and a pinion 95. The pinion shaft 98 can selectively advance the pinion 95 to engage the ring gear 99. The starter 96 can be directly mounted to the front or rear of the engine. In some examples, the starter 96 can selectively supply torque to the crankshaft 40 via a belt or chain. In one example, the starter 96 is in a basic state when not engaged with the engine crankshaft. In other examples, an integrated starter / generator (ISG) 111 can rotate the engine 10, and the ISG 111 can be directly connected to the crankshaft 40 or connected to the crankshaft 40 via a belt.

[0016] The combustion chamber 30 is shown in communication with the intake manifold 44 and the exhaust manifold 48 via respective intake valves 52 and exhaust valves 54. Each intake and exhaust valve can be operated by an intake cam 51 and an exhaust cam 53. The position of the intake cam 51 can be determined by an intake cam sensor 55. The position of the exhaust cam 53 can be determined by an exhaust cam sensor 57. The intake valves 52 can be selectively activated and deactivated by a valve actuator device 59. The exhaust valves 54 can be selectively activated and deactivated by a valve actuator device 58. The valve actuator devices 58 and 59 can be Figure 2 of the type shown or other known configurations.

[0017] The fuel injector 66 is shown positioned to inject fuel directly into the cylinder 30, which is referred to by those skilled in the art as direct injection. The fuel injector 66 delivers liquid fuel in proportion to a pulse width from the controller 12. The fuel is delivered to the fuel injector 66 by a fuel system (not shown) including a fuel tank, a fuel pump, and a fuel rail (not shown). In one example, a high pressure two-stage fuel system can be used to generate a higher fuel pressure.

[0018] In addition, the intake manifold 44 is shown in communication with a turbocharger compressor 162 and an engine air intake 42. In other examples, the compressor 162 can be a supercharger compressor. A shaft 161 mechanically couples a turbocharger turbine 164 to the turbocharger compressor 162. An optional electronic throttle 62 adjusts the position of a throttle plate 64 to control airflow from the compressor 162 to the intake manifold 44. The pressure in the plenum 45 can be referred to as the throttle inlet pressure because the inlet of the throttle 62 is within the plenum 45. The throttle outlet is in the intake manifold 44. In some examples, the throttle 62 and the throttle plate 64 can be positioned between the intake valves 52 and the intake manifold 44 such that the throttle 62 is an intake port throttle. The wastegate 163 can be adjusted via the controller 12 to allow exhaust gases to selectively bypass the turbine 164 to control the rotational speed of the compressor 162. An air cleaner 43 cleans air entering the engine air intake 42. The throttle 62 is positioned downstream of the compressor 162 in the direction of airflow into the engine 10.

[0019] The non-distributor ignition system 88 provides an ignition spark to the combustion chamber 30 via a spark plug 92 in response to the controller 12. A universal exhaust gas oxygen (UEGO) sensor 126 is shown coupled to the exhaust manifold 48 in the exhaust system 11 upstream of the catalytic converter 70. Alternatively, a two-state exhaust gas oxygen sensor can be substituted for the UEGO sensor 126. The engine exhaust system 11 includes the exhaust manifold 48, a temperature sensor 127, and the converter 70. In one example, the converter 70 can include multiple catalyst blocks. In another example, multiple emission control devices each having multiple blocks can be applied. In one example, the converter 70 can be a three-way catalyst.

[0020] The controller 12 is shown in Figure 1 The controller 12 is shown in

[0021] The controller 12 can also provide status information (e.g., an indication of deterioration or required maintenance) or receive input via a human / machine interface 175. The human / machine interface can be a touch screen panel, a button interface, or other type of interface.

[0022] During operation, each cylinder within engine 10 typically undergoes a four stroke cycle: the cycle includes an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke. During the intake stroke, generally, exhaust valve 54 is closed and intake valve 52 is open. Air is introduced into combustion chamber 30 via intake manifold 44, and piston 36 moves to the bottom of the cylinder to increase the volume within combustion chamber 30. The position of piston 36 near the bottom of the cylinder and at the end of its stroke, e.g., when combustion chamber 30 is at its maximum volume, is often referred to by those skilled in the art as bottom dead center (BDC).

[0023] During the compression stroke, both intake valve 52 and exhaust valve 54 are closed. Piston 36 moves toward the cylinder head to compress the air within combustion chamber 30. The point at which piston 36 is at the end of its stroke and closest to the cylinder head, e.g., when combustion chamber 30 is at its minimum volume, is often referred to by those skilled in the art as top dead center (TDC). During a process referred to hereinafter as injection, fuel is introduced into the combustion chamber. During a process referred to hereinafter as ignition, the injected fuel is ignited by a known ignition device, such as spark plug 92, resulting in combustion.

[0024] During the expansion stroke, the expanding gases push piston 36 back to BDC. Crankshaft 40 converts the piston motion to rotational torque of the rotational shaft. Finally, during the exhaust stroke, exhaust valve 54 opens to release the combusted air-fuel mixture to exhaust manifold 48, and the piston returns to TDC. It should be noted that the above is shown by way of example only, and the intake and exhaust valve opening and / or closing timing can vary, such as to provide positive or negative valve overlap, late intake valve closing, or various other examples.

[0025] Figure 2 An engine 10 is shown for application in Figure 1 An example cylinder valve actuator 58 in the shown engine 10. The cylinder valve actuator 58 adjusts the lift and / or valve open duration of the cylinder exhaust valve 54 in response to engine operating conditions. The cylinder valve actuator 58 can provide zero valve lift for one or more engine cycles to deactivate the cylinder exhaust valve 54. The exhaust camshaft 53 is shown positioned above the cylinder head 35 of a bank of engine cylinders. The exhaust valve 54 is configured to open and close a port in the cylinder, such as Figure 1 The exhaust port in the cylinder of the shown cylinder. For example, the exhaust valve 54 can actuate between an open position that allows gas exchange into and out of the cylinder and a closed position that substantially prevents gas exchange into and out of the cylinder. It should be understood that although Figure 2 only one valve is shown in the shown engine; however Figure 1 The shown engine 10 can include any number of cylinder valves. Additionally, cylinder valve actuators similar to the cylinder valve actuator 58 can be applied to engine intake valves. Furthermore,Figure 1 The engine 10 may include any number of cylinders with associated valves and may use a variety of different cylinder and valve configurations, such as V-6, I-4, I-6, V-12, opposed 4-cylinder and other engine types.

[0026] One or more camshaft towers or camshaft mounting areas may be connected to the cylinder head 35 to support the exhaust camshaft 53. For example, camshaft tower 216 is shown connected to the cylinder head 35 adjacent to the exhaust valve 54. Although Figure 2 The diagram shows a cam tower connected to the cylinder head; however, in other examples, the cam tower may be connected to other engine components, such as a cam bearing carrier or camshaft cover. The cam tower may support the overhead camshaft and can separate the lifting mechanism positioned on the camshaft above each cylinder.

[0027] The exhaust valve 54 can operate in multiple lift and duration modes, such as high valve lift, low or partial valve lift, short opening duration, long opening duration, and zero valve lift. For example, as described in more detail below, by adjusting the cylinder cam mechanism, valves on one or more cylinders, such as the exhaust valve 54, can operate in different lift modes based on engine operating conditions.

[0028] The exhaust camshaft 53 may include a plurality of cam lobes configured to control the opening and closing of the exhaust valve. For example, Figure 2 A first cam cam lob 212 and a second cam cam lob 214 positioned above valve 54 are shown. The cam lobes can have different shapes and sizes to form a lift profile for adjusting the amount and timing of valve 54 lift as the exhaust camshaft 53 rotates. For example, exhaust cam 212 can be a full-lift cam lob, and cam 214 can be a zero-lift cam lob. Although Figure 2 Two lift profiles associated with the first cam 212 and the second cam 214 are shown, but it should be understood that any number of lift profile cams may exist, for example, three different cam lobes.

[0029] The exhaust camshaft 53 includes a mechanism 218 coupled to the camshaft above the exhaust valve 54 for adjusting the valve lift amount for the exhaust valve 54 and / or for deactivating the exhaust valve by changing the cam lobe along the camshaft relative to the position of the exhaust valve 54. For example, the cam lobes 212 and 214 can be slidably attached to the camshaft such that the cam lobes can slide in an axial direction along the camshaft on a per cylinder basis. For example, a plurality of cam lobes, such as the cam lobes 212 and 214, positioned above each cylinder valve, such as the exhaust valve 54, can slide across the camshaft in the direction shown by arrow 245 to change the cam lobe profile coupled to the valve follower, such as the follower 220 coupled to the exhaust valve 54, to change the exhaust valve opening and closing duration and lift amount. The valve cam follower 220 can include a roller finger follower (RFF) 222 that engages with the cam lobe positioned above the valve 202. For example, in Figure 2 the roller 222 is shown engaged with the full lift cam lobe 212.

[0030] Figure 2 Additional follower elements not shown in FIG. 2 can also include pushrods, rocker arms, tappets, etc. Such devices and features can control the actuation of intake and exhaust valves by converting the rotational motion of the cam to translational motion of the valve. In other examples, the valves can be actuated via other cam lobe profiles on the camshaft, where the cam lobe profiles between different valves can provide varying cam lift heights, cam durations, and / or cam timing. However, alternative camshaft (overhead and / or pushrod) arrangements can be used if desired. Additionally, in some examples, the cylinders can each have only one exhaust valve and / or intake valve, or more than one intake and / or exhaust valve. In other examples, the exhaust and intake valves can be actuated by a common camshaft. However, in alternative examples, at least one of the intake and / or exhaust valves can be actuated by its own independent camshaft or other device.

[0031] The sleeve 224 is splined to the exhaust camshaft 53 and coupled to cam lobe angles 212 and 214. The camshaft position relative to the engine crankshaft is determined via a rotation-sensing camshaft position sensor 295 and an exhaust camshaft position indicator 290. The exhaust camshaft 53 may be coupled to a cam phaser used to change valve timing relative to the crankshaft position. The axial position of the sleeve can be repositioned by engaging a pin, such as pin 230 or 232, into a slotted socket in the sleeve, such that different cam lobe angles engage with the cam followers of the exhaust valve 54 to change the lift of the exhaust valve 54. For example, the sleeve 224 may include one or more displacement grooves, such as grooves 226 and 228, extending around the outer circumference of the sleeve. The displacement groove can have a helical configuration around the outer sleeve, and in some examples, a Y-shaped or V-shaped groove can be formed in the outer sleeve, wherein the Y-shaped or V-shaped groove is configured to engage two different drive pins, such as the first pin 230 and the second pin 232, at different times, so as to move the outer sleeve to change the lift profile of the exhaust valve 54. The pin 232 causes the sleeve 224 to move... Figure 2 When the pin is on the left, sleeve 224 is shown in the first position. As the profile changes, sleeve 224 follows spline 225 axially along exhaust camshaft 53. Additionally, the depth of each groove in sleeve 224 can decrease along the length of the groove, such that after the pin is deployed into the groove from its initial position, the pin can return to its initial position through the decreasing depth of the groove as the sleeve and camshaft rotate.

[0032] For example, such as Figure 3A As shown, when the first pin 230 is deployed into the recess 226, the outer sleeve 224 will move in one direction toward the cam tower 216 as the exhaust camshaft 53 rotates, thereby positioning the cam lobe 212 above the valve 202 and altering the valve lift profile. To switch back to the cam lobe 214, the second pin 232 can be deployed into the recess 228, which will move the outer sleeve 224 away from the cam tower 216 to position the cam lobe 214 above the valve 202. In some examples, multiple outer sleeves containing the cam lobe can be splined to the exhaust camshaft 53. For example, the outer sleeves can be coupled to the cam lobe above each valve in the engine 10 or a selected number of cam lobes above the valves.

[0033] Driver pins 230 and 232 are included in a cam lobe switching driver 234 that adjusts the position of pins 230 and 232 in order to switch the cam lobe that is positioned above valve 202. The exhaust cam lobe switching driver 234 includes an activation mechanism 236 that can be hydraulically driven, or electrically driven, or a combination thereof. Activation mechanism 236 changes the position of the pins in order to change the lift profile of the valve. For example, activation mechanism 236 can be a coil that is coupled to both pins 230 and 232, such that when the coil is energized, for example via current supplied to it from a control system, a force is applied to both pins to deploy both pins toward the sleeve.

[0034] Referring now to Figure 1 , an example multi-cylinder engine is shown that includes two cylinder groups. The engine includes a cylinder head 200 that includes two valves 202 and 204. The engine includes a cam lobe switching driver 234 that is coupled to the cylinder head 200. The cam lobe switching driver 234 includes a sleeve 238 that is coupled to the cylinder head 200. The sleeve 238 is coupled to the cylinder head 200 in a manner that allows the sleeve 238 to move relative to the cylinder head 200. The sleeve 238 is coupled to the cylinder head 200 in a manner that allows the sleeve 238 to move relative to the cylinder head 200 in a direction that is parallel to the axis of rotation of the camshaft 206. The sleeve 238 is coupled to the cylinder head 200 in a manner that allows the sleeve 238 to move relative to the cylinder head 200 in a direction that is perpendicular to the axis of rotation of the camshaft 206. The sleeve 238 is coupled to the cylinder head 200 in a manner that allows the sleeve 238 to move relative to the cylinder head 200 in a direction that is parallel to the axis of rotation of the camshaft 206 and in a direction that is perpendicular to the axis of rotation of the camshaft 206. Figure 1The illustrated cylinders and associated components. Engine 10 includes eight cylinders, each of which is labeled 310. Each of the eight cylinders has been numbered and the number of the cylinder is included within the cylinder. Fuel injectors 66 selectively supply fuel to each of the cylinders that are activated (e.g., combust fuel during a cycle of the engine). When less than full torque capacity of the engine is desired, cylinders 1-8 can be selectively deactivated to improve engine fuel economy. For example, cylinders 2, 3, 5, and 8 (e.g., a fixed pattern of deactivated cylinders) can be deactivated during an engine cycle (e.g., two revolutions for a four-stroke engine) and can be deactivated for multiple engine cycles while engine speed and load remain constant or vary slightly. During different engine cycles, a second fixed pattern of cylinders 1, 4, 6, and 7 can be deactivated. Additionally, other patterns of cylinders can be selectively deactivated based on vehicle operating conditions. Additionally, engine cylinders can be deactivated such that none of the cylinders of the fixed pattern are deactivated for multiple engine cycles. Rather, the deactivated cylinders can vary from one engine cycle to the next. Each cylinder includes a variable intake valve actuation 51 and a variable exhaust valve actuation 53. An engine cylinder can be deactivated by its variable intake valve actuation 51 and variable exhaust valve actuation keeping the intake and exhaust valves of the cylinder closed for the entire cycle of the cylinder. When a cylinder is deactivated, fuel flow to the cylinder stops. An engine cylinder can be activated by its variable intake valve actuation 51 and variable exhaust valve actuation 53 opening and closing the intake and exhaust valves of the cylinder during the cycle of the cylinder. Fuel is supplied to the activated cylinders, but the valves of the cylinder can open and close during the cycle of the cylinder without fuel being supplied to the cylinder during fuel cutoff at deceleration. Engine 10 includes a first cylinder group 304 that includes four cylinders 1, 2, 3, and 4. Engine 10 also includes a second cylinder group 302 that includes four cylinders 5, 6, 7, and 8. The cylinders of each group can be activated or deactivated during a cycle of the engine.

[0035] Engine 10 is also shown coupled to a transmission 320. Transmission 320 can be a fixed ratio transmission, a dual clutch transmission, a continuously variable transmission, or other known type of transmission. Sensor 322 can provide an indication of the position of shift selector 321. For example, sensor 322 can indicate that the transmission is engaged in park, neutral, reverse, or drive. The output of sensor 322 can be input to Figure 3B controller 12.

[0036] Referring now to Figure 1 , an example multi-cylinder engine including one cylinder group is shown. The engine includes a cylinder group as Figure 1The illustrated cylinders and associated components. Engine 10 includes four cylinders 310. Each of the four cylinders has been numbered and the number of the cylinder is included within the cylinder. Fuel injectors 66 selectively supply fuel to each of the cylinders that are activated (e.g., fuel is combusted during a cycle of the engine where the intake and exhaust valves are opened and closed during the cycle of the activated cylinder). Cylinders 1-4 can be selectively deactivated (e.g., fuel is not combusted during a cycle of the engine where the intake and exhaust valves remain closed throughout the cycle of the de-activated cylinder) to improve engine fuel economy when less than full torque capacity of the engine is required. For example, cylinders 2 and 3 (e.g., a fixed pattern of deactivated cylinders) can be deactivated during a plurality of engine cycles (e.g., two revolutions for a four stroke engine). During different engine cycles, a second fixed pattern of cylinders 1 and 4 can be deactivated for a plurality of engine cycles. Additionally, other patterns of cylinders can be selectively deactivated based on vehicle operating conditions. Additionally, engine cylinders can be deactivated such that none of the fixed pattern of cylinders are deactivated for a plurality of engine cycles. Rather, the deactivated cylinders can vary from one engine cycle to the next. In this manner, the deactivated engine cylinders can rotate or swap from one engine cycle to the next.

[0037] Engine 10 includes a single cylinder group 350 that includes four cylinders 1-4. During a cycle of the engine, the cylinders of the single group can be activated or deactivated. Each cylinder includes a variable intake valve actuation 51 and a variable exhaust valve actuation 53. An engine cylinder can be deactivated by its variable intake valve actuation 51 and variable exhaust valve actuation keeping the intake and exhaust valves of the cylinder closed during a cycle of the cylinder. Fuel flow is stopped to the deactivated cylinder. An engine cylinder can be activated by its variable intake valve actuation 51 and variable exhaust valve actuation 53 opening and closing the intake and exhaust valves of the cylinder during a cycle of the cylinder. Fuel is supplied to the activated cylinder, but the valves of the cylinder can be opened and closed during a cycle of the cylinder in the event fuel is shut off to the cylinder at deceleration.

[0038] Engine 10 is also shown coupled to a transmission 360. Transmission 360 can be a fixed ratio transmission, a dual clutch transmission, a continuously variable transmission, or other known type of transmission. Sensor 362 can provide an indication of the position of shift selector 361. For example, sensor 362 can indicate that the transmission is engaged in park, neutral, reverse, or drive. The output of sensor 362 can be input to Figures 1-3B controller 12.

[0039] Accordingly, Figure 4The system provides for an engine system comprising: an engine including one or more cylinder valve deactivation mechanisms and an exhaust system; an electric motor; and a controller including executable instructions stored in a non-transitory memory to adjust engine operation in response to an indication of deterioration of one or more cylinder valve deactivation mechanisms, the indication of deterioration being based on the temperature in the exhaust system when the electric motor rotates the engine and when no fuel is supplied to the engine. The indication of valve or valve actuator deterioration can be determined via a lack of temperature rise in the engine's exhaust system. The engine system also includes providing an indication of deterioration of one or more cylinder valve deactivation mechanisms in the absence of an exhaust temperature rise when the electric motor rotates the engine. The engine system includes wherein adjusting engine operation comprises activating one or more cylinder valve deactivation mechanisms. The engine system includes wherein adjusting engine operation comprises stopping fuel supply to one or more engine cylinders. The engine system also includes additional instructions for selectively activating a group of valve deactivation mechanisms at different times. The engine system also includes additional instructions for opening the engine throttle valve when the engine is rotated.

[0040] For reference Figure 4 This illustrates a first example of a predictive engine operating sequence for a four-cylinder (I4), four-stroke engine. Figures 1-3B The order of operations can be achieved through Figure 6 System execution Figure 7 and Figure 4 The instructions for the described method are used to generate it. Figure 4 The curves are aligned in time and occur simultaneously. The vertical markers at T0-T10 indicate the specific time of interest during the sequence. The horizontal axis includes time intervals indicated between two SSs positioned along the horizontal axis. The duration of these time intervals can be long or short.

[0041] From Figure 4 The first curve at the top represents the commanded valve mode versus time. The vertical axis represents the commanded valve mode. The horizontal axis represents time, and time increases from the left side of the curve towards the right side. In this example, the engine can only operate in two valve modes at a given time. Valve modes are indicated along the vertical axis, and these modes include I2 mode, which is used to operate the engine as a two-cylinder engine (e.g., the intake and exhaust valves of two engine cylinders open and close during the engine cycle, while the valves of two cylinders remain closed during the engine cycle); and I4 mode, which is used to operate the engine as a four-cylinder engine (e.g., the intake and exhaust valves of all four engine cylinders open and close during the engine cycle). Trace 402 represents the engine valve mode state.

[0042] From Figure 4 The second graph from the top represents engine operating state versus time. The vertical axis represents engine operating state, and when the trace 404 is at a higher level near the vertical axis arrow, the engine is operating (e.g., burning fuel). When the trace 404 is at a lower level near the horizontal axis, the engine is not operating (e.g., not burning fuel). The horizontal axis represents time, and time increases from the left-hand side of the graph toward the right-hand side of the graph. The trace 404 represents engine state.

[0043] From Figure 4 The third graph from the top represents temperature in the engine exhaust system (e.g., temperature of gases in the engine exhaust system) versus time. The vertical axis represents temperature in the engine exhaust system, and temperature increases in the direction of the vertical axis arrow. The horizontal axis represents time, and time increases from the left-hand side of the graph toward the right-hand side of the graph. The trace 406 represents temperature in the engine exhaust system.

[0044] From Figure 4 The fourth graph from the top represents engine speed versus time. The vertical axis represents engine speed, and engine speed increases in the direction of the vertical axis arrow. The horizontal axis represents time, and time increases from the left-hand side of the graph toward the right-hand side of the graph. The trace 408 represents engine speed.

[0045] From Figure 4 The fifth graph from the top represents engine throttle position versus time. The vertical axis represents engine throttle position, and the opening of the engine throttle increases in the direction of the vertical axis arrow. The horizontal axis represents time, and time increases from the left-hand side of the graph toward the right-hand side of the graph. The trace 410 represents throttle position.

[0046] From Figure 4 The sixth graph from the top represents valve and / or valve actuator degradation state versus time. The vertical axis represents valve and / or valve actuator degradation state, and when the valve degradation state trace is at a higher level near the vertical axis arrow, the valve and / or valve actuator is determined to have degraded. When the valve degradation state trace is at a lower level near the horizontal axis, the valve and / or valve actuator is determined to not have degraded. The horizontal axis represents time, and time increases from the left-hand side of the graph toward the right-hand side of the graph. The trace 412 represents valve degradation state.

[0047] From Figure 1The seventh plot at the top represents valve diagnostic request status versus time. The vertical axis represents valve diagnostic request status, and when the valve diagnostic request status trace is at a higher level near the vertical axis arrow, the valve and / or valve driver has requested to accept a diagnosis. When the valve diagnostic request status trace is at a lower level near the horizontal axis, no valve diagnosis is requested. The horizontal axis represents time, and time increases from the left-hand side of the plot toward the right-hand side of the plot. Trace 414 represents valve degradation status.

[0048] At time TO, the engine is operating in four cylinder mode, where all four engine cylinders are combusting fuel during a cycle of the engine. The intake and exhaust valves of each cylinder are opening and closing during the engine cycle. The exhaust system temperature is at an intermediate level, indicating that there is hot exhaust gas in the engine cylinders and exhaust system. The engine speed is at an intermediate level, and the engine throttle is partially open. The valve degradation status indicates that the valves and / or valve drivers are not degraded, and the valve diagnostic status indicates that no valve diagnosis is currently requested.

[0049] At time Tl, the engine continues to operate in four cylinder mode, but a valve diagnosis has been requested. The valve diagnosis can be requested in response to vehicle operating conditions (e.g., distance traveled by the vehicle, hours of engine operation, engine air-fuel ratio changes, etc.). The exhaust system temperature remains at a high temperature, and the engine speed remains at an intermediate level. The throttle remains at an intermediate position, and no valve degradation is indicated.

[0050] Just prior to time T2, an engine stop request (not shown) is asserted by a human or autonomous driving program, and the engine valves of two engine cylinders are commanded to be deactivated to trap exhaust gas in the two engine cylinders. In this example, the valves that are commanded to be deactivated transition to a deactivated state. The engine continues to operate, and the exhaust system temperature remains at an intermediate level. The engine speed also remains at an intermediate level. The throttle remains partially open, and no valve degradation is indicated.

[0051] At time T2, the engine is stopped (not combusting fuel) and the engine speed begins to decrease. The engine includes two cylinders with intake and exhaust valves that are activated (e.g., intake and exhaust valves that open and close during an engine cycle) and two cylinders with intake and exhaust valves that are deactivated (e.g., intake and exhaust valves that are commanded to remain closed for the entire engine cycle). When combustion is stopped, the exhaust temperature remains at an intermediate level and the engine speed is at an intermediate level. No valve degradation is indicated, and the valve diagnostic request remains asserted.

[0052] Between time T2 and time T3, the engine stops rotating and the valves of both cylinders are in an active mode (e.g., the intake and exhaust valves will open and close during engine cycles where the engine is rotating), and the valves of both cylinders are in an inactive mode (e.g., the intake and exhaust valves will not open during engine cycles where the engine is rotating). Since a small amount of air passes through the engine without participating in combustion as the engine decelerates to zero rotational speed, the exhaust system temperature decreases, then increases as the flow of air stops and the engine exhaust system heats the gas in the exhaust system. The throttle is fully closed, and no valve degradation is indicated. The valve diagnostic request remains asserted to indicate that the valve diagnostics remain active.

[0053] At time T3, with the valves of both cylinders remaining active and the valves of both cylinders remaining inactive, the engine is rotated via the electric machine (e.g., ISG 111) shown. Hot exhaust gas is trapped in the cylinders with inactive intake and exhaust valves. The engine speed begins to increase, and the engine is not combusting fuel. The throttle is opened to increase the flow of fresh air through the exhaust system. No valve and / or valve actuator degradation is indicated, and the valve diagnostic request remains asserted. Figure 1

[0054] Between time T3 and time T4, fresh air is pumped into the exhaust system via the cylinders with active intake and exhaust valves. Hot exhaust gas is still trapped in the engine cylinders with inactive intake and exhaust valves, and is doing work on the exhaust in the engine cylinders with inactive intake and exhaust valves. The exhaust system temperature decreases as fresh air is pumped through the exhaust system. The engine continues to rotate via the electric machine, and the throttle remains open. No valve and / or valve actuator degradation is indicated, and the valve diagnostic state remains asserted.

[0055] At time T4, the inactive intake and exhaust valves of both cylinders are commanded to active, so that the exhaust trapped in the cylinders with previously inactive intake and exhaust valves can be expelled into the exhaust system. The intake and exhaust valves activate in response to the command. The valve mode switches from I2 to I4 to indicate activation of the intake and exhaust valves. The engine is rotating by the electric machine, and there is no combustion in the engine cylinders. The engine speed continues to remain at its previous level, and the throttle remains open. No valve and / or valve actuator degradation is indicated, and the valve diagnostic request remains asserted.

[0056] ​Between time T4 and time T5, as hot gases are released from the two cylinders that previously had deactivated intake and exhaust valves, the exhaust temperature increases. The increase in exhaust temperature indicates that the previously deactivated intake and exhaust valves of the two cylinders are operating as expected. All engine intake and exhaust valves are activated, and the engine is not combusting. The engine continues to rotate via the electric machine at its previous rotational speed, and the throttle remains open. No valve and / or valve actuator degradation is indicated, and the valve diagnostic state remains asserted.

[0057] At time T5, the valve diagnostic request is withdrawn and the electric machine stops rotating the engine. The engine throttle closes, and no valve degradation is indicated. The engine remains in the I4 valve mode, and the engine is not combusting fuel.

[0058] In this way, the temperature of the exhaust system can confirm operation of the intake and exhaust valves. When performing the valve diagnostic, the engine does not need to combust air and fuel. Additionally, by not combusting fuel in the engine, the exhaust temperature can be controlled to indicate the presence or absence of valve and / or valve actuator degradation. Thus, the person driving the vehicle does not need to be disturbed to perform the valve diagnostic. The sequence continues until the time break between time T5 and time T6.

[0059] At time T6, the engine is operating in the four cylinder mode and requests a valve diagnostic. The exhaust system temperature is at a high temperature, and the engine rotational speed is at an intermediate level. The throttle is at an intermediate position, and no valve degradation is indicated.

[0060] Just prior to time T7, an engine stop request (not shown) is asserted by a person or autonomous driving program, and the intake and exhaust valves of two engine cylinders are commanded to deactivate to trap exhaust in the two engine cylinders. However, in this example, the intake and exhaust valves commanded to deactivate do not deactivate. The engine continues to operate, and the exhaust system temperature remains at an intermediate level. The engine rotational speed also remains at an intermediate level. The throttle remains partially open, and no valve degradation is indicated.

[0061] At time T7, the engine stops (does not combust fuel) and the engine rotational speed begins to decrease. The engine can be stopped via the stoppage of fuel supply to the engine. The engine includes two cylinders with activated intake and exhaust valves, and two cylinders with intake and exhaust valves that were commanded to deactivate but did not actually deactivate. When combustion stops, the exhaust temperature remains at an intermediate level and the engine rotational speed is at an intermediate level. No valve and / or valve actuator degradation is indicated, and the valve diagnostic request remains asserted.

[0062] Between time T7 and time T8, the engine stops rotating and the intake and exhaust valves of all cylinders are activated, but the intake and exhaust valves of two cylinders are still commanded to be deactivated. Since a small amount of air passes through the engine without participating in combustion when the engine is decelerating to zero speed, the exhaust system temperature decreases, then increases as the air flow stops and the engine exhaust system heats the gas in the exhaust system. The throttle is fully closed, and no valve and / or valve actuator degradation is indicated. The valve diagnostic request remains asserted to indicate that the valve diagnostics remain activated.

[0063] At time T8, with the intake and exhaust valves of all four cylinders remaining activated and the intake and exhaust valves of two cylinders commanded to be deactivated, the engine is rotated via the electric machine (e.g., ISG 111) shown. Hot exhaust gas will be trapped in the cylinders with deactivated intake and exhaust valves, but in this example, the intake and exhaust valves commanded to be deactivated continue to operate. The engine speed begins to increase, and the engine does not combust fuel. The throttle is opened to increase the flow of fresh air through the exhaust system. No valve and / or valve actuator degradation is indicated, and the valve diagnostic request remains asserted. Figure 5

[0064] Between time T8 and time T9, fresh air is pumped through all of the cylinders into the exhaust system. Thus, air is pumped through the cylinders whose intake and exhaust valves were commanded to be deactivated. The fresh air pumped through the engine lowers the temperature in the exhaust system. The engine continues to rotate via the electric machine, and the throttle remains open. No valve and / or valve actuator degradation is indicated, and the valve diagnostic state remains asserted.

[0065] At time T9, the intake and exhaust valves of the two cylinders commanded to be deactivated are commanded to be activated to determine whether the temperature in the exhaust system increases in response to reactivating the valves commanded to be deactivated. The valve pattern switches from I2 to I4 to indicate that all valves are commanded to be activated. The engine is rotating by the electric machine, and there is no combustion in the engine cylinders. The engine speed continues to remain at its previous level, and the throttle remains open. No valve and / or valve actuator degradation is indicated, and the valve diagnostic request remains asserted.

[0066] ​Between time T9 and time T10, the exhaust temperature continues to decrease because exhaust gas is not being discharged from the cylinders whose intake and exhaust valves were previously commanded to be deactivated into the exhaust system. The continued decrease in exhaust temperature indicates that the intake and exhaust valves of the two previously deactivated cylinders are not operating as expected. All engine intake and exhaust valves are activated, and the engine is not burning fuel. The engine continues to rotate via the electric motor at its previous speed, and the throttle remains open. Valve and / or valve actuator degradation is now indicated because the exhaust system temperature fails to rise after the deactivated intake and exhaust valves are restarted. The valve diagnostic status remains asserted. As described in further detail in the description of method 600, the engine actuators can be adjusted in response to the indication of valve and / or valve actuator degradation.

[0067] At time T10, the valve diagnostic request was withdrawn and the motor stopped rotating the engine. The engine throttle was closed, and no valve deterioration was indicated. The engine remained in I4 valve mode, and no fuel was burned.

[0068] In this way, the temperature of the exhaust system can confirm the deterioration of the intake and exhaust valves and their valve actuators. When performing intake and exhaust valve diagnostics, the engine does not need to burn air and fuel. Therefore, it is not necessary to disturb the driver to perform valve diagnostics.

[0069] For reference Figure 5 This illustrates an example predictive engine operating sequence for a four-cylinder (I4), four-stroke engine. Figures 1-3B The order of operations can be achieved through Figure 6 System execution Figure 7 and Figure 5 The instructions for the described method are used to generate it. Figure 5 The curves are aligned in time and occur simultaneously. The vertical markers at T20-T35 indicate specific times of interest during the stated sequence. The horizontal axis includes time intervals indicated between two SSs positioned along the horizontal axis. The duration of these time intervals can be long or short.

[0070] From Figure 5The first plot at the top represents commanded valve mode versus time. The vertical axis represents commanded valve mode. The horizontal axis represents time, and time increases from the left side of the plot toward the right side of the plot. In this example, the engine is capable of operating in one of four valve modes at a point in time. The valve modes are indicated along the vertical axis, and include an II mode for operating the engine as a single cylinder engine (e.g., one engine cylinder has intake and exhaust valves that open and close during an engine cycle, while the valves of three cylinders remain closed during the engine cycle), an I2 mode for operating the engine as a two cylinder engine (e.g., two engine cylinders have intake and exhaust valves that open and close during an engine cycle, while the valves of two cylinders remain closed during the engine cycle), an I3 mode for operating the engine as a three cylinder engine (e.g., three engine cylinders have intake and exhaust valves that open and close during an engine cycle, while the valves of one cylinder remain closed during the engine cycle), and an I4 mode for operating the engine as a four cylinder engine, where all intake and exhaust valves open and close during an engine cycle. Trace 502 represents the engine valve mode state.

[0071] From Figure 5 The second plot at the top represents engine operating state versus time. The vertical axis represents engine operating state, and the engine is operating (e.g., burning fuel) when trace 504 is at a higher level near the vertical axis arrow. The engine is not operating (e.g., not burning fuel) when trace 504 is at a lower level near the horizontal axis. The horizontal axis represents time, and time increases from the left hand side of the plot toward the right hand side of the plot. Trace 504 represents the engine state.

[0072] From Figure 5 The third plot at the top represents temperature in the engine exhaust system (e.g., temperature of gases in the engine exhaust system) versus time. The vertical axis represents temperature in the engine exhaust system, and temperature increases in the direction of the vertical axis arrow. The horizontal axis represents time, and time increases from the left hand side of the plot toward the right hand side of the plot. Trace 506 represents the temperature in the engine exhaust system.

[0073] From Figure 5 The fourth plot at the top represents engine speed versus time. The vertical axis represents engine speed, and engine speed increases in the direction of the vertical axis arrow. The horizontal axis represents time, and time increases from the left hand side of the plot toward the right hand side of the plot. Trace 508 represents the engine speed.

[0074] From Figure 5The fifth graph at the top represents engine throttle position versus time. The vertical axis represents engine throttle position, and the opening of the engine throttle increases in the direction of the vertical axis arrow. The horizontal axis represents time, and time increases from the left-hand side of the graph toward the right-hand side of the graph. Trace 510 represents throttle position.

[0075] From Figure 1 The sixth graph at the top represents valve and / or valve actuator deterioration status versus time. The vertical axis represents valve and / or valve actuator deterioration status, and the valve and / or valve actuator is determined to have deteriorated when the valve deterioration status trace is at a higher level near the vertical axis arrow. The valve and / or valve actuator is determined to be undeteriorated when the valve deterioration status trace is at a lower level near the horizontal axis. The horizontal axis represents time, and time increases from the left-hand side of the graph toward the right-hand side of the graph. Trace 512 represents valve deterioration status.

[0076] From Figure 1 The seventh graph at the top represents valve diagnostic request status versus time. The vertical axis represents valve diagnostic request status, and the valve and / or valve actuator has requested to accept a diagnosis when the valve diagnostic request status trace is at a higher level near the vertical axis arrow. No valve diagnosis is requested when the valve diagnostic request status trace is at a lower level near the horizontal axis. The horizontal axis represents time, and time increases from the left-hand side of the graph toward the right-hand side of the graph. Trace 514 represents valve deterioration status.

[0077] At time T20, the engine is operating in four cylinder mode, where all four engine cylinders are combusting fuel during a cycle of the engine. The intake and exhaust valves of each cylinder are opening and closing during the engine cycle. The exhaust system temperature is at an intermediate level, indicating that there is hot exhaust gas in the engine cylinders and the exhaust system. The engine speed is at an intermediate level, and the engine throttle is partially open. The valve deterioration status indicates that the valves and / or valve actuators are not deteriorated, and the valve diagnostic status indicates that no valve diagnosis is currently requested.

[0078] At time T21, the engine continues to operate in four cylinder mode, but a valve diagnosis has been requested. The valve diagnosis can be requested in response to vehicle operating conditions, such as distance traveled by the vehicle, hours of engine operation, engine air-fuel ratio changes, etc. The exhaust system temperature remains at a high temperature, and the engine speed remains at an intermediate level. The throttle remains at an intermediate position, and no valve deterioration is indicated.

[0079] Just prior to time T22, an engine stop request (not shown) is asserted by a human or autonomous driving program, and the engine valves of three engine cylinders are commanded to be deactivated to trap exhaust gas in the three engine cylinders. In this example, the valves commanded to be deactivated transition to a deactivated state. The engine continues to operate, and the exhaust system temperature remains at an intermediate level. The engine speed also remains at an intermediate level. The throttle remains partially open, and no valve degradation is indicated.

[0080] At time T22, the engine is stopped (not combusting fuel) and the engine speed begins to decrease. The engine includes one cylinder with intake and exhaust valves that are activated (e.g., intake and exhaust valves that open and close during engine cycles) and three cylinders with intake and exhaust valves that are deactivated (e.g., intake and exhaust valves that are commanded to remain closed throughout engine cycles). When combustion stops, the exhaust temperature remains at an intermediate level and the engine speed is at an intermediate level. No valve degradation is indicated, and the valve diagnostic request remains asserted.

[0081] Between time T22 and time T23, the engine is stopped from rotating and the valves of one cylinder are in an activated mode (e.g., intake and exhaust valves that will open and close during engine cycles of engine rotation) and the valves of three cylinders are in a deactivated mode (e.g., intake and exhaust valves that do not open during engine cycles of engine rotation). Since a small amount of air passes through the engine without participating in combustion as the engine decelerates to zero speed, the exhaust system temperature decreases and then increases as air flow stops and the engine exhaust system heats the gas in the exhaust system. The throttle is fully closed, and no valve degradation is indicated. The valve diagnostic request remains asserted to indicate that the valve diagnostics remain activated.

[0082] At time T23, with the valves of one cylinder remaining activated and the valves of three cylinders remaining deactivated, the engine is rotated via an electric machine (e.g., Figure 6 ISG 111 shown). Hot exhaust gas is trapped in the cylinder with deactivated intake and exhaust valves. The engine speed begins to increase, and the engine does not combust fuel. The throttle is opened to increase the flow of fresh air through the exhaust system. No valve degradation is indicated, and the valve diagnostic request remains asserted.

[0083] Between time T23 and time T24, fresh air is pumped through the exhaust system via one cylinder with the intake and exhaust valves activated. Hot exhaust gases are still trapped in the engine cylinder with the intake and exhaust valves deactivated, and work on the exhaust in the engine cylinder with the intake and exhaust valves deactivated. The exhaust system temperature decreases as fresh air is pumped through the exhaust system. The engine continues to rotate via the electric machine, and the throttle remains open. No valve degradation is indicated, and the valve diagnostic state remains asserted.

[0084] At time T24, the deactivated intake and exhaust valves of both cylinders are commanded to activate so that the exhaust trapped in the second cylinder with the previously deactivated intake and exhaust valves can be expelled into the exhaust system. The intake and exhaust valves activate in response to the command. The valve pattern switches from II to I2 to indicate the commanded activation of the intake and exhaust valves of both cylinders. The engine is rotating by the electric machine, and there is no combustion in the engine cylinders. The engine speed continues to maintain its previous level, and the throttle remains open. No valve and / or valve actuator degradation is indicated, and the valve diagnostic request remains asserted.

[0085] Between time T24 and time T25, the exhaust temperature increases slightly as hot gases are released from one cylinder with the previously deactivated intake and exhaust valves. The increase in exhaust temperature indicates that the intake and exhaust valves of the previously deactivated cylinder (e.g., the second cylinder) are operating as expected. The engine is not combusting fuel, and continues to rotate via the electric machine. The engine continues to rotate at its previous speed, and the throttle remains open. No valve and / or valve actuator degradation is indicated, and the valve diagnostic state remains asserted.

[0086] At time T25, the deactivated intake and exhaust valves of three cylinders are commanded to activate so that the exhaust in the third cylinder with the previously deactivated intake and exhaust valves can be expelled into the exhaust system. The intake and exhaust valves activate in response to the command. The valve pattern switches from I2 to I3 to indicate the commanded activation of the intake and exhaust valves of three cylinders. The engine is rotating by the electric machine, and there is no combustion in the engine cylinders. The engine speed continues to maintain its previous level, and the throttle remains open. No valve and / or valve actuator degradation is indicated, and the valve diagnostic request remains asserted.

[0087] Between time T25 and time T26, the exhaust temperature increases slightly as hot gases are released from the one cylinder that previously had deactivated intake and exhaust valves. The increase in exhaust temperature indicates that the intake and exhaust valves of the previously deactivated cylinder (e.g., the third cylinder) are operating as expected. The engine is not combusting fuel and continues to rotate via the electric machine. The engine continues to rotate at its previous speed and the throttle remains open. No indication of valve and / or valve actuator degradation is indicated and the valve diagnostic status remains asserted.

[0088] At time T26, the intake and exhaust valves of all four cylinders are commanded to activate so that exhaust gases in the fourth cylinder, which previously had deactivated intake and exhaust valves, can be expelled into the exhaust system. The intake and exhaust valves activate in response to the command. The valve mode switches from I3 to I4 to indicate the commanded activation of the intake and exhaust valves of all four cylinders. The engine is rotating by the electric machine and there is no combustion in the engine cylinders. The engine speed continues to maintain its previous level and the throttle remains open. No indication of valve degradation is indicated and the valve diagnostic request remains asserted.

[0089] Between time T26 and time T27, the exhaust temperature increases slightly as hot gases are released from the one cylinder that previously had deactivated intake and exhaust valves. The increase in exhaust temperature indicates that the intake and exhaust valves of the previously deactivated cylinder (e.g., the fourth cylinder) are operating as expected. The engine is not combusting fuel and continues to rotate via the electric machine. The engine continues to rotate at its previous speed and the throttle remains open. No indication of valve and / or valve actuator degradation is indicated and the valve diagnostic status remains asserted.

[0090] At time T27, the valve diagnostic request is withdrawn and the electric machine stops rotating the engine. The engine throttle is closed and no indication of valve degradation is indicated. The engine remains in the I4 valve mode and the engine is not combusting fuel.

[0091] In this way, the temperature of the exhaust system can confirm the operation of the intake and exhaust valves of individual cylinders. The engine does not need to combust air and fuel when performing the valve diagnostics. Thus, a more comprehensive intake and exhaust valve diagnostic can be performed. The sequence continues to be performed until the time break between time T27 and time T28.

[0092] Before time T28, the engine is operating in a four cylinder mode in which all four engine cylinders are combusting fuel during a cycle of the engine. The intake and exhaust valves of each cylinder are opening and closing during the engine cycle. The exhaust system temperature is at an intermediate level, indicating the presence of hot exhaust gas in the engine cylinders and exhaust system. The engine speed is at an intermediate level, and the engine throttle is partially open. The valve degradation status indicates that the valves and / or valve actuators are not degraded, and the valve diagnostic status indicates that a valve diagnostic is not currently requested.

[0093] At time T28, the engine continues to operate in the four cylinder mode, but a valve diagnostic has been requested. The exhaust system temperature remains at a high temperature, and the engine speed remains at an intermediate level. The throttle remains at an intermediate position, and no valve degradation is indicated.

[0094] Just before time T29, an engine stop request (not shown) is asserted, provided by a human or autonomous driving program, and the engine valves of three engine cylinders are commanded to be deactivated to trap exhaust gas in the three engine cylinders. In this example, the valve of the second cylinder commanded to be deactivated fails to transition to the deactivated state, but the valves of the remaining cylinders comply with their respective commands. The engine continues to operate, and the exhaust system temperature remains at an intermediate level. The engine speed also remains at an intermediate level. The throttle remains partially open, and no valve degradation is indicated.

[0095] At time T29, the engine stops (fuel is not combusted) and the engine speed begins to decrease. The engine includes one cylinder with intake and exhaust valves that are activated (e.g., intake and exhaust valves that open and close during an engine cycle) and three cylinders with intake and exhaust valves that are deactivated (e.g., intake and exhaust valves that are commanded to remain closed for an entire engine cycle). When combustion stops, the exhaust temperature remains at an intermediate level and the engine speed is at an intermediate level. No valve and / or valve actuator degradation is indicated, and the valve diagnostic request remains asserted.

[0096] Between time T29 and time T30, the engine stops rotating and the valves of one cylinder are in an activated mode (e.g., intake and exhaust valves that will open and close during an engine cycle of engine rotation) and the valves of three cylinders are in a deactivated mode (e.g., intake and exhaust valves that do not open during an engine cycle of engine rotation). Because a small amount of air passes through the engine without participating in combustion as the engine decelerates to zero speed, the exhaust system temperature decreases and then increases as air flow stops and the engine exhaust system heats the gas in the exhaust system. The throttle is fully closed, and no valve degradation is indicated. The valve diagnostic request remains asserted to indicate that the valve diagnostic remains activated.

[0097] At time T30, the engine is rotating via the electric machine (e.g., ISG 111) as the valve of one cylinder is commanded to activate and the valves of three cylinders are commanded to deactivate. However, due to degradation of the valve actuator of the second cylinder, the valves of the first and second cylinders remain activated. Hot exhaust gases are trapped in the cylinder with deactivated intake and exhaust valves. The engine speed begins to increase and the engine does not combust fuel. The throttle is opened to increase the flow of fresh air through the exhaust system. The valve and / or valve actuator degradation is not indicated and the valve diagnostic request remains asserted. Figure 7

[0098] Between time T30 and time T31, fresh air is pumped into the exhaust system via the two cylinders with activated intake and exhaust valves despite the valves of three cylinders being commanded to deactivate. Hot exhaust gases are still trapped in the engine cylinder with deactivated intake and exhaust valves and work is done on the exhaust in the engine cylinder with deactivated intake and exhaust valves. As fresh air is pumped through the exhaust system via the two cylinders, the exhaust system temperature decreases. The engine continues to rotate via the electric machine and the throttle remains open. The valve and / or valve actuator degradation is not indicated and the valve diagnostic state remains asserted.

[0099] At time T31, the deactivated intake and exhaust valves of the second cylinder are commanded to activate along with the intake and exhaust valves of the first cylinder so that it can be determined whether hot exhaust gases are trapped in the second cylinder that previously had deactivated intake and exhaust valves. The intake and exhaust valves activate in response to the command. The valve pattern switches from II to I2 to indicate the mandated activation of the intake and exhaust valves of two cylinders. The engine is rotating by the electric machine and there is no combustion in the engine cylinder. The engine speed continues to maintain its previous level and the throttle remains open. The valve degradation is not indicated and the valve diagnostic request remains asserted.

[0100] Between time T31 and time T32, the exhaust temperature is not increased but decreased due to the intake and exhaust valves of the second cylinder not deactivating when they were commanded to deactivate. The decrease in exhaust temperature indicates that the intake and exhaust valves of the previously deactivated cylinder (e.g., second cylinder) are not operating as expected. The engine does not combust fuel and continues to rotate via the electric machine. The engine continues to rotate at its previous speed and the throttle remains open. The valve degradation is not indicated and the valve diagnostic state remains asserted.

[0101] ​At time T32, the valves and / or valve actuators are indicated to be deteriorating. The second cylinder can be specifically indicated to be the cylinder with deteriorating intake and exhaust valves since the intake and exhaust valves of the second cylinder were separately commanded to activate and the exhaust gas temperature did not increase. As described in further detail in the description of method 600, the engine actuator can be adjusted in response to the indication of deteriorating valves and / or valve actuators.

[0102] At time T33, the deactivated intake and exhaust valves of the third cylinder are commanded to activate along with the intake and exhaust valves of the first and second cylinders so that it can be determined whether hot exhaust gas is trapped in the third cylinder that previously had deactivated intake and exhaust valves. The intake and exhaust valves are activated in response to the command. The valve pattern is switched from I2 to I3 to indicate the commanded activation of the intake and exhaust valves of three cylinders. The engine is rotating by the electric machine and there is no combustion in the engine cylinders. The engine speed continues to maintain its previous level and the throttle remains open. The valves and / or valve actuators are still indicated to be deteriorating and the valve diagnostic request remains asserted so that the intake and exhaust valves of the remaining cylinders can be diagnosed.

[0103] Between time T33 and time T34, the exhaust gas temperature slightly increases as hot gas is released from the cylinder that previously had deactivated intake and exhaust valves. The increase in exhaust gas temperature indicates that the intake and exhaust valves of the previously deactivated cylinder (e.g., the third cylinder) are operating as expected. The engine is not combusting fuel and continues to rotate via the electric machine. The engine continues to rotate at its previous speed and the throttle remains open. The valves and / or valve actuators are still indicated to be deteriorating and the valve diagnostic state remains asserted.

[0104] At time T34, the intake and exhaust valves of all four cylinders are commanded to activate so that exhaust gas in the fourth cylinder that previously had deactivated intake and exhaust valves can be expelled into the exhaust system. The intake and exhaust valves activate in response to the command. The valve pattern is switched from I3 to I4 to indicate the commanded activation of the intake and exhaust valves of all four cylinders. The engine is rotating by the electric machine and there is no combustion in the engine cylinders. The engine speed continues to maintain its previous level and the throttle remains open. The valves and / or valve actuators are indicated to be deteriorating and the valve diagnostic request remains asserted.

[0105] Between time T34 and time T35, the exhaust temperature increases slightly as hot gas is released from a cylinder that previously had deactivated intake and exhaust valves. The increase in exhaust temperature indicates that the intake and exhaust valves of the previously deactivated cylinder (e.g., the fourth cylinder) are operating as expected. The engine does not combust fuel and continues to rotate via the electric machine. The engine continues to rotate at its previous rotational speed and the throttle remains open. Valve degradation is still indicated and the valve diagnostic state remains asserted.

[0106] At time T35, the valve diagnostic request is withdrawn and the electric machine stops rotating the engine. The engine throttle closes and valve degradation is not indicated. The engine remains in the I4 valve mode and the engine does not combust fuel.

[0107] In this way, the temperature of the exhaust system can confirm operation of the intake and exhaust valves of individual cylinders. When performing a valve diagnostic, the engine does not need to combust air and fuel. Therefore, a more comprehensive intake and exhaust valve diagnostic can be performed.

[0108] Referring now to Figure 6 and Figure 7 , a method for operating an engine and determining valve actuator degradation via engine exhaust temperature is described. Figures 1-3B and Figure 6 The methods of Figure 7 may be incorporated into and can cooperate with the systems of Figure 5 and Figure 1 Additionally, at least portions of the methods of and

[0109] may be incorporated as executable instructions stored in non-transitory memory while other portions of the methods can be performed via a controller that causes a transition in the operational state of a device and actuator in the real world. Additionally, when performing the method 600, the engine can be operated via combustion of fuel and rotates according to a four-stroke cycle.

[0110] At 604, the method 600 determines whether a cylinder valve actuator diagnosis is required. In one example, a cylinder valve actuator diagnosis can be required after the vehicle has traveled a predetermined distance, after the cylinder valves have been deactivated for more than a threshold amount of time, and in situations where the vehicle operating conditions are suitable for a cylinder valve actuator diagnosis. A cylinder valve actuator diagnosis can be required after the vehicle passengers have exited the vehicle, in situations where the vehicle is being remotely started, or in situations where the vehicle is a hybrid vehicle and the driver demand is low enough that the engine can be stopped. If the method 600 determines that a cylinder valve actuator diagnosis is required, the answer is yes and the method 600 proceeds to 606. Otherwise, the answer is no and the method 600 proceeds to 695.

[0111] At 695, the method 600 operates the engine with intake and exhaust poppet valves that are operable to open and close during engine cycles. The method 600 can also operate the engine with poppet valves and actuators that command the intake and exhaust valves to be activated. For example, if the engine is a V8 engine and the engine includes V6, V4, and V2 cylinder modes, all of the modes can be available and entered depending on the driver demand torque and vehicle speed. However, if the valve actuators are diagnosed as having deteriorated such that the valves can not be activated and deactivated as commanded, the engine can be prevented from entering the V2 and V4 cylinder modes. The particular cylinder mode that is activated can depend on the driver demand torque and engine speed or vehicle speed. Additionally, if an intake or exhaust valve or valve actuator is determined to have deteriorated, the method 600 can limit the amount of torque that the engine produces based on the deteriorated valve or valve actuator. For example, the method 600 can prevent fuel flow to a cylinder whose intake or exhaust valves are unable to open and close as commanded. Additionally, the method 600 can prevent spark delivery to the same cylinder. The engine operates via combustion of fuel according to a four-stroke cycle. The method 600 proceeds to exit.

[0112] At 606, the method 600 determines whether the engine includes valve actuators for activating (e.g., activated intake and exhaust valves that open and close during each engine cycle) and deactivating (e.g., deactivated intake and exhaust valves that do not open and close during each engine cycle) each valve of each engine cylinder. The method 600 can determine whether the engine includes valve actuators for activating and deactivating each poppet valve of each engine cylinder according to a value of a variable that indicates a configuration of the engine. If the value of the variable indicates that the engine includes valve actuators for activating and deactivating each poppet valve of each cylinder, the answer is yes and the method 600 proceeds to 608. Otherwise, the answer is no and the method 600 proceeds to 650.

[0113] At 608, method 600 determines whether an engine stop has been requested and whether the transmission is engaged in park. In one example, an engine stop can be requested by a human driver providing input to a push-button switch, button, or other device with the sole purpose of requesting an engine stop or start. Alternatively, the autonomous driving program can request an engine stop by adjusting the value of a variable in the controller's memory. Similarly, method 600 can determine whether the vehicle's transmission is engaged in park by determining the position of the gearshift via a sensor. If method 600 determines that an engine stop has been requested and the vehicle's transmission is engaged in park, the answer is yes and method 600 proceeds to 610. Otherwise, the answer is no, and method 600 proceeds to 695.

[0114] At point 610, method 600 disables the intake and exhaust valves of the selected engine cylinder, stops combustion in the engine, and closes the engine throttle valve. In such cases... Figure 4 In one example shown, all intake and exhaust valves of all engine cylinders except for the intake and exhaust valves of one engine cylinder can be deactivated, such that the intake and exhaust valves remain closed for the entire duration of an engine rotation through an engine cycle (e.g., two revolutions). In other examples, the intake and exhaust valves of predetermined engine cylinders can be deactivated. Deactivating the intake and exhaust valves of a cylinder leaves each cylinder closed and prevents the exhaust of afterburner gases. Method 600 proceeds to 612.

[0115] At 612, method 600 determines whether combustion in the engine has ceased. Combustion may continue until each cylinder, including the deactivated intake and exhaust valves, retains post-combustion exhaust products. For example, if cylinder 1 is in the intake stroke when the engine is requested to stop, combustion continues until the air introduced into cylinder 1 participates in combustion along with the fuel injected into cylinder 1. Then, by not opening the exhaust valve of cylinder 1 after combustion occurs during the compression stroke, combustion byproducts remain trapped in cylinder 1. Similarly, combustion may continue in other engine cylinders until each engine cylinder whose intake and exhaust valves are commanded to be deactivated captures combustion byproducts (e.g., exhaust). If method 600 determines that combustion in the engine has ceased, the answer is yes and method 600 proceeds to 614. Otherwise, the answer is no, and method 600 returns to 612.

[0116] At 614, method 600 is via a motor (e.g., Figure 1ISG 111 or starter 96) to rotate the engine. By rotating the engine, the gases in the exhaust system can be cooled such that hot exhaust leaving a cylinder with deactivated intake and exhaust valves can be distinguished from cool air passing through a cylinder with activated intake and exhaust valves. While the engine is rotating, the engine exhaust system is cooled by flowing air through the cylinders with activated valves. The method 600 proceeds to 616.

[0117] At 616, the method 600 determines the engine exhaust system temperature. In one example, the method 600 can determine the temperature of the exhaust in the engine exhaust system via a temperature sensor. The output of the temperature sensor is provided to the controller to determine the engine exhaust system temperature. The method 600 proceeds to 618.

[0118] At 618, the method 600 determines whether the temperature of the exhaust system has increased since the intake and exhaust valves of the deactivated cylinder were reactivated. The method 600 can compare the temperature of the exhaust shortly before the intake and exhaust valves were activated to the output of the temperature sensor indicating the temperature of the exhaust shortly after the intake and exhaust valves of the cylinder were reactivated (within two engine cycles). If the method 600 determines that a higher temperature of the exhaust is observed, the answer is yes and the method 600 proceeds to 620. If the method 600 determines that a higher temperature of the exhaust is not observed, the answer is no and the method 600 proceeds to 630 if the method 600 entered step 618 without reactivating the intake and exhaust valves of the selected cylinder since the intake and exhaust valves were deactivated at 610. If the method 600 determines that a higher temperature of the exhaust is not observed and the method 600 has reactivated the intake and exhaust valves of the selected cylinder since the intake and exhaust valves were deactivated at 610, the answer is no and the method 600 proceeds to 630.

[0119] At 630, the method 600 indicates that valve degradation exists for the cylinder whose intake and exhaust valves were recently reactivated. The indication can be made via changing the value of a variable in memory. Additionally, the method 600 can provide a visual or audible indication in the passenger compartment of the vehicle via a human / machine interface. The method 600 proceeds to 632.

[0120] At 632, the method 600 adjusts the engine drive in response to the valve and valve driver degradation. In one example, where the intake valve and / or exhaust valve and / or valve driver of a cylinder is determined to have degraded, the method 600 stops supplying fuel to the cylinder with the degraded valve and / or valve driver. In another example, the method 600 can prevent other engine cylinders from being deactivated based on the intake valve and / or exhaust valve and / or valve driver such that the engine can only operate in a small number of the total number of available cylinder modes. For example, a V8 engine can be allowed to only operate in V8 and V6 modes, and the V8 engine can be prevented from entering a V4 cylinder mode. Additionally, the method 600 can adjust the engine throttle in response to a first engine airflow and MAP relationship in the absence of intake valve and exhaust valve or valve driver degradation, and the method 600 can adjust the engine throttle in response to a second engine airflow and MAP relationship in the presence of intake valve and exhaust valve or valve driver degradation. The engine drive can be adjusted in response to the valve driver degradation when the engine is restarted and combusting fuel. After adjusting the engine drive, the method 600 proceeds to 620.

[0121] At 620, the method 600 determines whether the engine has rotated a threshold amount of time since the most recent time the intake valve and exhaust valve of a cylinder were commanded to activate. For example, the intake valve and exhaust valve of cylinder four can be commanded to activate at time ti; if the method 600 determines that a threshold amount of time has passed since time ti, the answer is yes and the method 600 proceeds to 622. The answer is yes and the method 600 proceeds to 622 if the method 600 determines that the engine has rotated a threshold amount of time since the most recent time the intake valve and exhaust valve of a cylinder were commanded to activate. Otherwise, the answer is no and the method 600 returns to 616.

[0122] At 622, the method 600 determines whether all intake valves and exhaust valves of all engine cylinders have been activated after deactivating the selected intake valve and exhaust valve at 610. In one example, the activation and / or deactivation of the intake valve and exhaust valve of a cylinder can be indicated by a value of a variable stored in the controller memory. The answer is yes and the method 600 proceeds to 626 if the value of the variable indicates that all intake valves and exhaust valves of all engine cylinders of the engine have been commanded to activate. Otherwise, the answer is no and the method 600 proceeds to 625.

[0123] At 626, the method 600 stops engine rotation via the motor and closes the throttle. After stopping engine rotation and closing the engine throttle, the method 600 exits.

[0124] At 625, the method 600 activates the intake and exhaust valves of the next cylinder whose valves were deactivated at 610. For example, if the four cylinder engine has deactivated the intake and exhaust valves of cylinders 2, 3, and 4 at 610 and has activated the intake and exhaust valves of cylinder 2, the method 600 can activate the intake and exhaust valves of cylinder 3. The method 600 returns to 616.

[0125] In this manner, the method 600 can selectively deactivate and activate the intake and exhaust valves of individual cylinders, where individual control of the intake and exhaust valves is provided. If a temperature increase in the exhaust system is detected upon reactivation of the deactivated intake and exhaust valves, it can be determined that the intake and exhaust valves and their actuators are operating as expected. If a temperature increase in the engine exhaust system is not detected upon reactivation of the deactivated intake and exhaust valves, it can be determined that the intake and exhaust valves and their actuators are not operating as expected.

[0126] At 650, the method 600 determines whether the engine stop has been requested and whether the transmission is engaged in park. In one example, the engine stop can be requested via a human driver providing input to a key switch, button, or other device having the sole purpose of requesting the engine to stop or start. Alternatively, an autonomous driving program can request the engine stop via adjusting the value of a variable in the controller memory. Similarly, the method 600 can determine whether the transmission of the vehicle is engaged in park by determining the position of the shift lever via a sensor. If the method 600 determines that the engine stop has been requested and that the transmission of the vehicle is engaged in park, the answer is yes and the method 600 proceeds to 652. Otherwise, the answer is no and the method 600 proceeds to 696.

[0127] At 696, method 600 operates the engine using intake and exhaust lift valves operable to open and close during the engine cycle. Method 600 can also operate the engine using lift valves and actuators that activate the intake and exhaust valves upon command. For example, if the engine is a V8 engine and includes V6, V4, and V2 cylinder modes, all modes may be available and the engine may enter all modes based on the driver's torque demand and vehicle speed. However, if the valve actuators are diagnosed as deteriorated, making it impossible to activate and deactivate the valves as commanded, the engine may be prevented from entering V2 and V4 cylinder modes. The specific cylinder mode activated may depend on the driver's torque demand and engine speed or vehicle speed. Additionally, if the intake or exhaust valves or valve actuators are determined to be deteriorated, method 600 can limit the amount of torque produced by the engine based on the deteriorated valves or valve actuators. For example, method 600 can prevent fuel flow to cylinders where the intake or exhaust valves are unable to open and close in response to commands. Additionally, method 600 prevents sparks from being delivered to the same cylinder. The engine operates by burning fuel according to a four-stroke cycle. Method 600 proceeds to exit.

[0128] At point 652, method 600 disables the intake and exhaust valves of the selected engine cylinder, stops combustion in the engine, and closes the engine throttle valve. In such cases... ​ In one example shown, all intake and exhaust valves of a portion of the engine cylinders can be deactivated, such that the intake and exhaust valves remain closed throughout the entire duration of an engine rotation through an engine cycle (e.g., two revolutions). For example, the intake and exhaust valves of cylinders 1 and 3 of a four-cylinder engine can be deactivated. In one example, the engine may not be able to deactivate the intake and exhaust valves of individual cylinders. Instead, it may be possible to deactivate only a group of cylinders. Method 600 deactivates the intake and exhaust valves of the engine cylinders and proceeds to 654.

[0129] At 654, the method 600 determines whether combustion in the engine has ceased. Combustion can be allowed to continue until each cylinder, including the deactivated intake and exhaust valves, retains combustion after products. For example, if cylinder one is on an intake stroke at the time the engine is requested to stop, the engine continues combustion until the air introduced into cylinder one participates in combustion with the fuel injected into cylinder one. The combustion byproducts are then still trapped in cylinder one by not opening the exhaust valve of cylinder one after combustion occurs during the compression stroke of cylinder one. Similarly, combustion can continue in other engine cylinders until each engine cylinder commanded to deactivate the intake and exhaust valves traps combustion byproducts (e.g., exhaust gases). If the method 600 determines that combustion in the engine has ceased, the answer is yes and the method 600 proceeds to 656. Otherwise, the answer is no and the method 600 returns to 654.

[0130] At 656, the method 600 rotates the engine via an electric machine (e.g., the ISG 111 or starter 96). By rotating the engine, gases in the exhaust system can be cooled such that hot exhaust gases exiting a cylinder previously having deactivated intake and exhaust valves can be distinguished from cool air passing through a cylinder having activated intake and exhaust valves. The method 600 proceeds to 658. ​

[0131] At 658, the method 600 determines an engine exhaust system temperature. In one example, the method 600 can determine a temperature of exhaust gases in the engine exhaust system via a temperature sensor. The output of the temperature sensor is provided to a controller to determine the engine exhaust system temperature. The method 600 proceeds to 660.

[0132] At 660, the method 600 determines whether the temperature of the exhaust system has increased after reactivation of the intake and exhaust valves of the deactivated cylinder. The method 600 can compare the temperature of the exhaust system after reactivation of the intake and exhaust valves of the one or more cylinders to the temperature of the exhaust system shortly before activation of the intake and exhaust valves. The output of the temperature sensor indicates a higher temperature of the exhaust gases shortly after reactivation of the intake and exhaust valves of one or more cylinders in the case that the answer is yes and the method 600 proceeds to 662. If the method 600 determines that a higher temperature of the exhaust gases is observed, the answer is yes and the method 600 proceeds to 662. If the method 600 determines that a higher temperature of the exhaust gases is not observed, the method 600 proceeds to 662 if the method 600 entered step 660 without reactivation of the intake and exhaust valves after deactivation of the intake and exhaust valves of the selected cylinder at 652. If the method 600 determines that a higher temperature of the exhaust gases is not observed and the method 600 has commanded reactivation of the intake and exhaust valves after deactivation of the intake and exhaust valves of the selected cylinder at 652, the answer is no and the method 600 proceeds to 670. ​

[0133] At 670, the method 600 indicates that there is valve degradation for one or more cylinders for which the intake and exhaust valves were most recently restarted. The indication can be made via changing a value of a variable in memory. Additionally, the method 600 can provide a visual or audible indication in a passenger cabin of the vehicle via a human / machine interface. The method 600 proceeds to 672.

[0134] At 672, the method 600 adjusts the engine drive in response to the valve and / or valve driver degradation. In one example, where the intake and / or exhaust valves and / or valve driver of a cylinder are determined to have degraded, the method 600 stops supplying fuel to the cylinder with the degraded valve and / or valve driver. In another example, the method 600 can prevent other engine cylinders from being deactivated based on the intake and / or exhaust valves and / or valve driver, such that the engine can only operate in a small number of the total number of available cylinder modes. For example, a V8 engine can be allowed to operate only in V8 and V6 modes, and can be prevented from entering a V4 cylinder mode. Additionally, the method 600 can adjust the engine throttle in response to a first engine airflow and MAP relationship when there is no intake and exhaust valve or valve driver degradation, and the method 600 can adjust the engine throttle in response to a second engine airflow and MAP relationship when there is intake and exhaust valve or valve driver degradation. The engine drive can be adjusted in response to the valve driver degradation when the engine is restarted and combusting fuel. After adjusting the engine drive, the method 600 proceeds to 662.

[0135] At 662, the method 600 determines whether the engine has rotated a threshold amount of time since the intake and exhaust valves of the cylinder were most recently commanded to start. For example, the intake and exhaust valves of cylinders one and four of a four cylinder engine can be commanded to start at time tl; if the method 600 determines that a threshold amount of time has passed since time tl, the answer is yes and the method 600 proceeds to 664. The answer is yes and the method 600 proceeds to 664 if the method 600 determines that the engine has rotated a threshold amount of time since the intake and exhaust valves of one or more cylinders were most recently commanded to start. Otherwise, the answer is no and the method 600 returns to 658.

[0136] At 664, the method 600 determines whether all intake valves and exhaust valves of all engine cylinders have been activated after deactivating the selected intake valves and exhaust valves at 652. In one example, activation and / or deactivation of the intake valves and exhaust valves of the cylinders can be indicated by a value of a variable stored in the controller memory. If the value of the variable indicates that all intake valves and exhaust valves of all engine cylinders of the engine have been commanded to activate, then the answer is yes and the method 600 proceeds to 666. Otherwise, the answer is no and the method 600 proceeds to 665.

[0137] At 666, the method 600 stops engine rotation via the electric machine and closes the throttle. After stopping engine rotation and closing the engine throttle, the method 600 exits.

[0138] At 665, the method 600 activates the intake valves and exhaust valves of the next cylinder whose valves were deactivated at 652. For example, if a four cylinder engine has deactivated the intake valves and exhaust valves of cylinders 2 and 3 at 652 and has not activated the intake valves and exhaust valves of cylinders 2 and 3, the method 600 can activate the intake valves and exhaust valves of cylinders 2 and 3. The method 600 returns to 658.

[0139] In this way, the method 600 can selectively deactivate and activate the intake valves and exhaust valves of cylinders included in a set of cylinders where individual control of the intake valves and exhaust valves is not provided. If a temperature increase is detected upon reactivation of the deactivated intake valves and exhaust valves, it can be determined that the intake valves and exhaust valves and their drivers are operating as expected. If a temperature increase is not detected upon reactivation of the deactivated intake valves and exhaust valves, it can be determined that the intake valves and exhaust valves and their drivers are not operating as expected.

[0140] Accordingly, the method 600 provides an engine operating method comprising: causing, via a controller, an engine to rotate without combusting fuel; indicating, in response to a lack of a temperature increase in an exhaust system, a deterioration of a valve actuator after commanding activation of a poppet valve of one or more engine cylinders while causing the engine to rotate without combusting fuel; and adjusting operation of the engine in response to the indication of the deterioration of the valve actuator. The method further comprises determining the lack of the temperature increase via an output of a temperature sensor. The method further comprises detecting the lack of the temperature increase in the exhaust system. The method includes where adjusting the operation of the engine comprises activating all cylinders of the engine. The method includes where adjusting the operation of the engine comprises stopping a supply of fuel to the one or more engine cylinders.

[0141] In some examples, the method further includes rotating the engine, where the intake valves and the exhaust valves of the one or more cylinders are operated while the engine is rotated without combusting fuel prior to commanding the activation of the poppet valves. The method includes where the poppet valves include intake valves and exhaust valves. The method includes where the engine is rotated via an integrated starter / generator. The method further includes indicating an absence of valve actuator degradation in response to an increase in temperature in the exhaust system. The method further includes deactivating the poppet valves of one or more engine cylinders prior to or during the rotating the engine without combusting fuel.

[0142] The method 600 further provides an engine operating method including requesting a diagnosis of one or more intake valves and exhaust valves, deactivating intake poppet valves and exhaust poppet valves of a first cylinder during engine stop in response to the request to diagnose the one or more intake valves and exhaust valves, rotating the engine without combusting fuel via a controller, indicating valve actuator degradation in response to an absence of an increase in temperature in an exhaust system after activating the intake poppet valves and the exhaust poppet valves of the first cylinder while the engine is rotated without combusting fuel, and adjusting operation of the engine in response to the indication of valve actuator degradation. The method includes detecting the absence of the increase in temperature in the exhaust system after activating the intake valves and the exhaust valves. The method includes where deactivating the intake poppet valves and the exhaust poppet valves includes keeping the intake poppet valves and the exhaust poppet valves closed for an entire engine cycle. The method further includes indicating an absence of valve actuator degradation in response to a presence of an increase in temperature in the exhaust system after activating the intake poppet valves and the exhaust poppet valves. The method further includes deactivating intake poppet valves and exhaust poppet valves of a second cylinder during engine stop. The method further includes indicating valve actuator degradation in response to an absence of an increase in temperature in the exhaust system after activating the intake poppet valves and the exhaust poppet valves of the second cylinder while the engine is rotated without combusting fuel, the intake poppet valves and the exhaust poppet valves of the second cylinder being activated after the intake poppet valves and the exhaust poppet valves of the first cylinder are activated for a predetermined amount of time. The method includes detecting the absence of the increase in temperature in the exhaust system after activating the intake valves and the exhaust valves of the second cylinder.

[0143] It will be appreciated that the configurations and methods disclosed herein are exemplary in nature, and that these specific examples are not to be considered in a limiting sense, because numerous variations are possible. For example, the above technology can be applied to V-6, I-4, I-6, V-12, opposed 4 cylinder, and other engine types. The subject matter of the present disclosure includes all novel and nonobvious combinations and subcombinations of the various systems and configurations, and other features, functions, and / or properties disclosed herein.

[0144] Certain combinations and subcombinations of elements from the following claims are specifically intended to be recognized as mere conversation starters. Such claims may refer to "a" or "first" element or to "one" element or to an "element" without creating a single or monolithic element to encompass a combination of elements. Developing claims that stem from this same aspect of the disclosure can be recognized as presenting additional subsets of elements that can be claimed. Such claims can be identified where they omit, substitute, add or modify some of the elements recognized as including a single or monolithic element. These multiple owner claims, if any, can be developed with via modification of the others claims. It is the intention of the original claim owner to retain and not release their ownership of these subsidiary claims if any, and to require others to account for them if used, identified, or otherwise communicated. This disclosure is not a disclaimer of ownership of these subsidiary claims by the original claim owner, irrespective of whether any of the subsidiary claims are ever actually claimed, developed and / or used.

[0145] According to the present invention, an engine operating method includes causing, via a controller, an engine to rotate without combusting fuel; indicating, in response to a lack of a temperature increase in an exhaust system, actuator degradation of a valve driver after commanding activation of a poppet valve of one or more engine cylinders while causing the engine to rotate without combusting fuel; and adjusting operation of the engine in response to the indication of the actuator degradation of the valve driver.

[0146] According to one embodiment, the present invention is further characterized by determining the lack of the temperature increase via an output of a temperature sensor.

[0147] According to one embodiment, adjusting the engine operation includes activating all cylinders of the engine.

[0148] According to one embodiment, adjusting the engine operation includes stopping fuel supply to one or more engine cylinders.

[0149] According to one embodiment, the present invention is further characterized by causing the engine to rotate, wherein intake and exhaust valves of the one or more cylinders are operated while causing the engine to rotate without combusting fuel prior to commanding activation of the poppet valve.

[0150] According to one embodiment, the poppet valve includes an intake valve and an exhaust valve.

[0151] According to one embodiment, the engine is caused to rotate via an integrated starter / generator.

[0152] According to one embodiment, the present invention is further characterized by indicating an absence of actuator degradation of the valve driver in response to a temperature increase in the exhaust system.

[0153] According to one embodiment, the present invention is further characterized by deactivating the poppet valve of one or more engine cylinders prior to or during causing the engine to rotate without combusting fuel.

[0154] According to the invention, an engine operating method includes deactivating intake and exhaust poppet valves of a first cylinder during engine stop in response to a request to diagnose one or more intake and exhaust valves; causing the engine to rotate without combusting fuel via a controller; indicating valve actuator degradation in response to a lack of an increase in temperature in an exhaust system after activating the intake and exhaust poppet valves of the first cylinder while causing the engine to rotate without combusting fuel; and adjusting operation of the engine in response to the indication of valve actuator degradation.

[0155] According to one embodiment, deactivating the intake and exhaust poppet valves includes keeping the intake and exhaust poppet valves closed for an entire engine cycle.

[0156] According to one embodiment, the invention is further characterized by indicating an absence of valve actuator degradation in response to an existence of an increase in temperature in the exhaust system after activating the intake and exhaust poppet valves.

[0157] According to one embodiment, the invention is further characterized by deactivating intake and exhaust poppet valves of a second cylinder during engine stop.

[0158] According to one embodiment, the invention is further characterized by indicating valve actuator degradation in response to a lack of an increase in temperature in the exhaust system after activating the intake and exhaust poppet valves of the second cylinder while causing the engine to rotate without combusting fuel, the intake and exhaust poppet valves of the second cylinder being activated after the intake and exhaust poppet valves of the first cylinder are activated for a predetermined amount of time.

[0159] According to the invention, an engine system includes an engine including one or more cylinder deactivation mechanisms and an exhaust system, an electric machine, and a controller including executable instructions stored in non-transitory memory to adjust operation of the engine in response to an indication of degradation of the one or more cylinder deactivation mechanisms, the indication of degradation being based on a temperature in the exhaust system while the electric machine is causing the engine to rotate and while there is no fuel supply to the engine.

[0160] According to one embodiment, the invention is further characterized by providing the indication of degradation of the one or more cylinder deactivation mechanisms in the absence of an increase in exhaust temperature while the electric machine is causing the engine to rotate.

[0161] According to one embodiment, adjusting operation of the engine includes activating the one or more cylinder deactivation mechanisms.

[0162] According to one embodiment, adjusting operation of the engine includes stopping a supply of fuel to one or more engine cylinders.

[0163] According to one embodiment, the application is further characterized by additional instructions for selectively activating the set of valve deactivation mechanisms at different times.

[0164] According to one embodiment, the application is further characterized by additional instructions for opening the engine throttle when the engine is rotating.

Claims

1. An engine operating method, the engine operating method comprising: The engine is rotated without burning fuel via a controller; After commanding the activation of the lift valves of one or more engine cylinders while the engine is rotating without burning fuel, valve actuator deterioration is indicated in response to a lack of temperature rise in the exhaust system; and The operation of the engine is adjusted in response to the indication of deterioration of the valve actuator.

2. The method of claim 1, further comprising determining the lack of the temperature rise via the output of a temperature sensor.

3. The method of claim 1, wherein adjusting engine operation includes starting all cylinders of the engine.

4. The method of claim 1, wherein adjusting engine operation includes stopping the supply of fuel to one or more engine cylinders.

5. The method of claim 1, further comprising rotating the engine, wherein the intake and exhaust valves of one or more cylinders operate while rotating the engine without burning fuel, prior to commanding the activation of the lift valve.

6. The method of claim 1, wherein the lift valve comprises an intake valve and an exhaust valve.

7. The method of claim 1, wherein the engine is rotated via an integrated starter / generator.

8. The method of claim 1, further comprising indicating the absence of valve actuator deterioration in response to a temperature rise in the exhaust system.

9. The method of claim 8, further comprising deactivating a lift valve of the one or more engine cylinders before or during the rotation of the engine without burning fuel.

10. An engine system, the engine system comprising: An engine, the engine including one or more cylinder valve deactivation mechanisms and an exhaust system; Electric motor; as well as A controller, comprising executable instructions stored in a non-transitory memory, for adjusting the operation of the engine in response to an indication of deterioration of the one or more cylinder valve deactivation mechanisms, the indication of deterioration being based on the temperature in the exhaust system when the motor rotates the engine and when no fuel is supplied to the engine.

11. The engine system of claim 10, further comprising providing an indication of the degradation of the one or more cylinder valve deactivation mechanisms when the exhaust temperature does not rise while the motor is rotating the engine.

12. The engine system of claim 10, wherein adjusting the engine operation includes activating the one or more cylinder valve deactivation mechanisms.

13. The engine system of claim 10, wherein adjusting the operation of the engine includes stopping the supply of fuel to one or more engine cylinders.

14. The engine system of claim 10, further comprising additional instructions for selectively activating the valve deactivation mechanism assembly at different times.

15. The engine system of claim 10, further comprising additional instructions for opening the engine throttle valve when the engine is rotated.

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