CONTROL UNIT FOR VARIABLE DISPLACEMENT ENGINE

Abstract

Engine control procedures, comprehensive: Increasing the actual total number of available cylinder modes from an initial total number of available cylinder modes to a second total number of available cylinder modes via a controller in response to a road unevenness estimate exceeding a threshold; and Operating an engine via the control system in a cylinder deactivation mode after increasing the actual total number of available cylinder modes, wherein the cylinder deactivation mode is initiated after counting an actual total number of engine events following an initial estimate of road unevenness exceeding a threshold, the initial estimate being made after a final estimate of road unevenness that did not exceed the threshold.

Description

Area

[0001] The present description relates to a system and method for operating an engine during conditions where one or more cylinders of the engine may be temporarily deactivated to improve the fuel efficiency of the engine. The methods and system provide opportunities to increase an operating range of an engine where one or more cylinders of the engine may be temporarily deactivated to improve the fuel efficiency of the vehicle. Background and brief presentation

[0002] One or more cylinders of an engine may be temporarily deactivated to improve the vehicle's fuel efficiency. The one or more cylinders may be deactivated by cutting off fuel and spark to the deactivated cylinders. Additionally, airflow into and out of the deactivated cylinders may be prevented or at least significantly reduced by closing the intake and exhaust valves of the deactivated cylinders. Air or exhaust gases may be trapped in the deactivated cylinders to maintain higher pressures in the deactivated cylinders and to recycle energy used to compress gases in the cylinders.

[0003] From the document DE 38 12 599 C2 a motor vehicle with a multi-cylinder internal combustion engine is known, in which a road condition sensor is used to determine whether the road surface is even or uneven in order to then switch off the fuel supply to a greater or lesser number of cylinders depending on the condition of the road surface.

[0004] The engine crankshaft and firing order are defined to reduce engine noise and vibration when the engine operates with all of its cylinders in an active state. Engine torque production and engine speed may be smoothest (e.g., produce the least deviation from the desired engine torque and engine speed) when the engine is operating with its full complement of cylinders. If one or more engine cylinders are deactivated, the engine torque deviation and engine speed deviation from the desired values ​​may increase due to longer intervals between combustion events. Thus, engine fuel efficiency may be increased by deactivating cylinders, but noise and vibration from the engine, as perceived by vehicle occupants, may increase.When the engine operates at higher levels of noise and vibration, vehicle occupants may find driving unpleasant. Thus, it may be difficult to deliver higher levels of fuel efficiency without compromising the driving experience.

[0005] These problems are solved by the features of the independent patent claims; advantageous developments of the invention are the subject of the subclaims.

[0006] The inventors of this application have recognized the above-mentioned disadvantages and developed an engine control method comprising: increasing the actual total number of available cylinder modes from a first actual total number of available cylinder modes to a second actual total number of available cylinder modes via a controller in response to an estimate of roughness of a road exceeding a threshold; and operating an engine via the controller in a cylinder deactivation mode after increasing the actual total number of available cylinder modes.

[0007] By increasing the actual total number of available cylinder modes in response to an estimation that road roughness exceeds a threshold, it may be possible to provide the technical result of operating an engine in a cylinder deactivation mode at a time when vehicle occupants are less likely to perceive the additional engine noise and vibration. For example, when a vehicle is traveling on a rough road, the actual total number of available cylinder modes may be increased to allow the engine to operate with two or more cylinders deactivated, while cylinder deactivation for the engine may be prevented based on engine speed and torque when the vehicle is operating on a smooth road but under otherwise similar conditions.

[0008] The present description may offer several advantages. In particular, the approach may provide improved vehicle fuel efficiency. Additionally, the approach may reduce the potential for disturbing vehicle occupants while cylinders are deactivated. Further, the approach may enable or disable cylinder deactivation modes in response to a suspended or unsuspended vehicle mass, so that fuel efficiency may be increased while making vehicle occupants less sensitive to noise and vibration that may be associated with engine cylinder deactivation.

[0009] The above advantages and other advantages and features of the present description will be readily apparent from the following Detailed Description taken alone or in conjunction with the accompanying drawings. Brief description of the drawings

[0010] The advantages described herein will be more fully appreciated by reading an example of an embodiment, referred to herein as the detailed description, when considered alone or with reference to the drawings, in which: Fig. 1 is a schematic diagram of an engine; Fig. 2A and Fig. 2B are schematic diagrams of example engine configurations; Fig. 3A and Fig. 3B shows examples of cylinder deactivation regions; Fig. 4A-4C show various vehicle suspension components and configurations; and Fig. 5-6 show a flowchart of an exemplary method for controlling a motor. Detailed description

[0011] This description relates to improving engine operation and vehicle drivability during conditions where engine cylinders can be deactivated to improve vehicle fuel efficiency. Fig. The cylinders of an engine shown in Figures 1-2B may be selectively deactivated to improve the engine's fuel efficiency. The engine cylinders may be deactivated within an engine operating range defined by engine speed and load, as shown in Fig. 3A and Fig. 3B. The engine cylinders can be deactivated based on the acceleration of vehicle components, as shown in Fig. 4A-4C is shown. Fig. 5-6 show an exemplary method for operating an engine that includes cylinders that can be deactivated.

[0012] Referring to Fig. 1, an internal combustion engine 10 comprising a plurality of cylinders, one of which is in Fig. 1, is controlled by an electronic engine controller 12. The engine 10 includes a combustion chamber 30 and cylinder walls 32 with a piston 36 disposed therein and is connected to a crankshaft 40. The combustion chamber 30 is shown in communication with an intake manifold 44 and an exhaust manifold 48 via a respective intake valve 52 and exhaust valve 54. Each intake and exhaust valve may be actuated by an intake cam 51 and an exhaust cam 53. The position of the intake cam 51 may be determined by an intake cam sensor 55. The position of the exhaust cam 53 may be determined by an exhaust cam sensor 57. The intake cam 51 and exhaust cam 53 may be moved relative to the crankshaft 40. The intake valves may be deactivated and maintained in a closed state via an intake valve deactivation mechanism 59.The exhaust valves can be deactivated and maintained in a closed state via an exhaust valve deactivation mechanism 58.

[0013] A fuel injector 66 is shown arranged to inject fuel directly into the cylinder 30, known to those skilled in the art as direct injection. Alternatively, the fuel may be injected into an intake port, known to those skilled in the art as port fuel injection. The fuel injector 66 delivers liquid fuel proportional to the pulse width of a signal from the controller 12. Fuel is supplied to the fuel injector 66 by a fuel system 175, which includes a tank and a pump. Additionally, the intake manifold 44, as shown, communicates with an optional electronic throttle 62 (e.g., a butterfly valve) that adjusts a position of the throttle plate 64 to control airflow from the air cleaner 43 and air intake 42 to the intake manifold 44. The throttle 62 regulates airflow from the air cleaner 43 into the engine air intake 42 to the intake manifold 44.In some examples, the throttle 62 and the throttle plate 64 may be positioned between the intake valve 52 and the intake manifold 44 such that the throttle 62 is a manifold throttle.

[0014] A distributorless ignition system 88 provides an ignition spark to the combustion chamber 30 via a spark plug 92 in response to the controller 12. A wideband oxygen sensor (UEGO) 126 is shown coupled to the exhaust manifold 48 upstream of a catalytic converter 70. Alternatively, a dual-state exhaust gas oxygen sensor may replace the wideband oxygen sensor 126.

[0015] In one example, the catalyst 70 may include multiple catalyst bricks. In another example, multiple emission control devices, each with multiple bricks, may be used. In one example, the catalyst 70 may be a three-way catalyst.

[0016] The control 12 is in Fig. 1 as a conventional microcomputer comprising: a microprocessor unit 102, input / output ports 104, a read-only memory 106 (e.g., non-volatile memory), a random access memory 108, a keep-alive memory 110, and a conventional data bus.The controller 12 is shown receiving various signals from sensors connected to the engine 10, in addition to the signals previously discussed, including: engine coolant temperature (ECT) from a temperature sensor 112 coupled to a cooling sleeve 114; a position sensor 134 coupled to an accelerator pedal 130 to measure the force applied by a human driver 132; a measurement of engine manifold pressure (MAP) from a pressure sensor 122 coupled to the intake manifold 44; an engine position sensor from a Hall effect sensor 118 that detects the position of the crankshaft 40; a measurement of an air mass entering the engine from a sensor 120; a brake pedal position from a brake pedal position sensor 154 when the human driver 132 applies the brake pedal 150; and a measurement of the throttle position from a sensor 58.Barometric pressure may also be sensed for processing by controller 12 (sensor not shown). In a preferred aspect of the present description, engine position sensor 118 generates a predetermined number of evenly spaced pulses with each revolution of the crankshaft, from which engine speed (RPM) can be determined. Controller 12 may receive input from a human-machine interface 115 (e.g., a push button or touchscreen display).

[0017] In some examples, the engine may be coupled to an electric motor / battery system in a hybrid vehicle. In some examples, other engine configurations may also be used, such as a diesel engine.

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

[0019] Referring to Fig. 2A shows a first configuration of engine 10. Engine 10 includes two cylinder banks, 202 and 204. The first cylinder bank, 204, includes cylinders 210, numbered 1-4. The second cylinder bank, 202, includes cylinders 210, numbered 5-8. Thus, the first configuration is a V8 engine with two cylinder banks. When all cylinders are operating, this may be a first cylinder operating mode.

[0020] During selected conditions, one or more cylinders 210 may be deactivated by no longer supplying fuel to the deactivated cylinders. Additionally, airflow into the deactivated cylinders may be adjusted by closing and maintaining the intake and exhaust valves of the deactivated cylinders closed. The engine cylinders may be deactivated in a variety of patterns to provide a desired actual total number of activated or deactivated cylinders. For example, cylinders 2, 3, 5, and 8 may be deactivated to form a first pattern of deactivated cylinders and a second cylinder operating mode. Alternatively, cylinders 1, 4, 6, and 7 may be deactivated to form a second pattern of deactivated cylinders and a third cylinder operating mode.In another example, cylinders 2 and 8 may be deactivated to form a third pattern of deactivated cylinders and a fourth cylinder operating mode. In yet another example, cylinders 3 and 5 may be deactivated to form a fourth pattern of deactivated cylinders and a fifth cylinder operating mode. In this example, five cylinder operating modes are provided; however, additional or fewer cylinder operating modes may be provided. If the engine conditions are such that the engine can operate in any of the described five cylinder modes, the engine may be described as having five available cylinder operating modes. In this example, if two of the five engine operating modes are unavailable, the engine may be described as having three available operating modes. The engine always has one available cylinder operating mode (e.g.,all cylinders are active and burning air and fuel). Of course, the actual total number of available operating modes may be more or fewer than five, depending on the engine configuration.

[0021] Referring to Fig. Figure 2B shows a second configuration of engine 10. Engine 10 includes a 206-cylinder bank. Bank 206 includes 210 cylinders, numbered 1-4. Thus, the second configuration is a single-bank I4 engine. When all cylinders are operating, this may be a first cylinder operating mode for this engine configuration.

[0022] Similar to the first configuration, one or more cylinders 210 may be deactivated by no longer supplying fuel to the deactivated cylinders. Additionally, airflow into the deactivated cylinders may be adjusted by closing and maintaining the intake and exhaust valves of the deactivated cylinders closed. The engine cylinders may be deactivated in a variety of patterns to provide a desired actual total number of activated or deactivated cylinders. For example, cylinders 2 and 3 may be deactivated to form a first pattern of deactivated cylinders and a second cylinder operating mode. Alternatively, cylinders 1 and 4 may be deactivated to form a second pattern of deactivated cylinders and a third cylinder operating mode.In another example, cylinder 2 may be deactivated to form a third pattern of deactivated cylinders and a fourth cylinder operating mode. In yet another example, cylinder 3 may be deactivated to form a fourth pattern of deactivated cylinders and a fifth cylinder operating mode. In this example, if the engine conditions are such that the engine can operate in any of the described five cylinder modes, the engine may be described as having five available cylinder operating modes. If two of the five engine operating modes are unavailable, the engine may be described as having three available operating modes. The engine always has one available cylinder operating mode (e.g., all cylinders are active and burning air and fuel). Of course, the actual total number of available operating modes may be more or fewer than five, depending on the engine configuration.

[0023] In still other examples, different cylinder configurations may be provided. For example, the engine may be a V6 engine or a V10 engine. The different engine configurations may also have a different number of cylinder operating modes.

[0024] Referring to Fig. 3A shows an example cylinder deactivation region 302 for an eight-cylinder engine. The cylinder deactivation region 302 is shown as rectangular, but may be defined by other polygons or shapes, such as a curve, that defines a region. The region 302 is defined by a first engine speed 304, a second engine speed 306, a first engine torque 308, and a second engine torque 310. The second engine speed 306 is higher than the first engine speed 304. The second engine torque 310 is greater than the first engine torque 308. Cylinder modes with four and eight cylinders active may be available within the region 302. The eight-cylinder mode is the only cylinder mode available outside of the region 302. Modes with two active cylinders (e.g., cylinders where air and fuel are combusted) are not available in the region 302. The cylinder modes may be unavailable due to engine noise and vibration.Thus, the actual total number of available cylinder modes within cylinder deactivation region 302 is greater than outside cylinder deactivation region 302. Such a cylinder deactivation region may be applied when a vehicle is traveling on a slippery road. The relatively small size of region 302 and the cylinder modes available within region 302 reduce the possibility of providing uncomfortable vehicle operating conditions for vehicle occupants. The scale of . Fig. 3A is equal to that for Fig. 3B.

[0025] Referring to Fig. 3B, an exemplary second cylinder deactivation region 320 for an eight-cylinder engine is shown as a solid line. The cylinder deactivation region 320 is shown as a trapezoidal shape, but may be defined by other polygons or shapes, such as a curve, that define a region. The region 320 is defined by a first engine speed 322, a second engine speed 324, a first engine torque 326, and a second engine torque 328. The second engine speed 324 is higher than the first engine speed 322. The second engine torque 328 is greater than the first engine torque 326.

[0026] A cylinder deactivation region 330 is outlined with a dashed line. Region 330 is defined by a first engine speed 322, a second engine speed 323, a first engine torque 326, and a second engine torque 327. The second engine speed 323 is higher than the first engine speed 322. The second engine torque 327 is greater than the first engine torque 326.

[0027] Accordingly, Fig. 3B shows two cylinder deactivation regions. Cylinder modes with four and eight cylinders active may be available within region 320. The eight-cylinder mode is the only cylinder mode available outside of region 320 and outside of region 330. Cylinder modes with two active cylinders, four active cylinders, and eight active cylinders are available in region 330. The cylinder modes may be unavailable due to engine noise and vibration. Thus, the actual total number of available cylinder modes within cylinder deactivation region 330 is greater than within region 320 and outside cylinder deactivation regions 330 and 320. Such cylinder deactivation regions may be applied when a vehicle is traveling on rough road surfaces. The larger region encompassing regions 320 and 330 increases the potential for improving vehicle fuel efficiency.Furthermore, the additional cylinder modes available in range 330 can also further increase fuel efficiency. Thus, the engine operating range in which cylinder deactivation modes are available increases when the vehicle is traveling on rough roads, where engine noise and vibration that may occur due to engine cylinder deactivation are less noticeable. Furthermore, the actual total number of available cylinder modes can be increased, as road roughness can mask engine noise and vibration from vehicle occupants.

[0028] Referring to Fig. 4A shows an exemplary vehicle 402 in which the engine 10 may be housed. The vehicle 402 includes a three-axis accelerometer 404 that can sense the vertical acceleration, longitudinal acceleration, and lateral acceleration of the sprung chassis. The vertical, longitudinal, and lateral directions are indicated by the illustrated coordinates. Sprung chassis components are components supported by the spring suspension. Thus, the body 405 is a sprung mass, while the wheel 490 is an unsprung mass. Fig. 4B and Fig. 4C show additional examples of sprung and unsprung masses.

[0029] Fig. 4B shows an exemplary body suspension 410 for vehicle 402 or a similar vehicle. A tire 412 is mounted on a wheel (not shown), and the wheel is mounted on a hub 408. Hub 408 is mechanically connected to a lower control arm 419 and an upper control arm 420. Upper control arm 420 and lower control arm 419 can pivot about a chassis support 403, which may be part of the vehicle body. A spring 415 is connected to chassis support 403 and lower control arm 419 such that spring 415 supports chassis support 403. Hub 408, upper control arm 420, and lower control arm 419 are unsprung, as they are not supported by spring 415, and they move according to a surface of the road on which the vehicle is traveling. A shock absorber (not shown) may accompany spring 415 to provide a second order system.An accelerometer 409 may sense the vertical acceleration of unsprung chassis components, while an accelerometer 435 may sense the vertical acceleration of sprung chassis components. The accelerometer 409 may provide a more direct indication of how the unsprung chassis components respond to the road surface. The accelerometer 435 may provide an indication of how the sprung chassis components respond to the road surface conditions reaching the sprung chassis components. Furthermore, the accelerometer 435 may provide an indication of engine vibration related to cylinder deactivation, which may reach the sprung chassis components and the vehicle occupants.

[0030] The output of accelerometer 409 can provide an improved basis for determining how much road-related noise vehicle occupants can perceive due to the movement of unsprung chassis components and tire noise, compared to the output of accelerometer 435, which detects the acceleration of a sprung mass. This can be particularly true if the spring suspension and / or shock absorbers have been replaced with different components or if they are in poor condition. The output of accelerometer 435 can detect engine vibration and accelerations that cannot be inferred or detected by accelerometer 409 due to the spring suspension and shock absorbers.

[0031] Fig. 4C shows another exemplary body suspension 450 for vehicle 402 or a similar vehicle. A tire 412 is mounted on a wheel (not shown), and the wheel is mounted on a hub 457. Hub 457 is mechanically connected to an axle 461. A spring 451 is connected to the chassis 455 and axle 461. Hub 408 and axle 461 are unsprung, as they are not supported by spring 451, and they move according to a surface of the road on which the vehicle is traveling. A shock absorber (not shown) may accompany spring 451 to provide a second-order system. An accelerometer 452 may sense the vertical acceleration of unsprung chassis components, while an accelerometer 459 may sense the vertical acceleration of sprung chassis components.Accelerometer 452 may provide a more direct indication of how the unsprung chassis components respond to the road surface. Accelerometer 459 may provide an indication of how the sprung chassis components respond to the road surface conditions reaching the sprung chassis components. Furthermore, accelerometer 459 may provide an indication of engine vibration related to cylinder deactivation, which may reach the sprung chassis components and the vehicle occupants.

[0032] The output of accelerometer 452 may provide an improved basis for determining how much road-related noise vehicle occupants may perceive due to the movement of unsprung chassis components and tire noise, compared to the output of accelerometer 459, which detects the acceleration of a sprung mass. This may be particularly true if the spring suspension and / or shock absorbers have been replaced with different components or if they are in poor condition. The output of accelerometer 459 may detect engine vibration and accelerations that cannot be inferred or detected by accelerometer 452 due to the spring suspension and shock absorbers.

[0033] Referring to Fig. 5 and Fig. 6 shows an exemplary flowchart for a method for operating an engine. The method of Fig. 5 and Fig. 6 can be found in the system of Fig. 1 and Fig. 2 and may interact with it. Furthermore, at least parts of the procedure may be Fig. 5 and Fig. 6 may be included as executable instructions stored in a non-volatile memory, while other parts of the method may be performed via a controller that converts operating states of devices and actuators in the physical world.

[0034] At 502, method 500 determines a mode of the vehicle's suspension. In one example, the vehicle may have two or more modes, including track (e.g., stiff or rigid suspension), sport (e.g., medium stiffness suspension), and cruise (e.g., compliant suspension). The suspension mode may be determined via a user input device. Method 500 proceeds to 504.

[0035] At 504, method 500 determines a vertical acceleration frequency and force of a sprung vehicle mass, such as a chassis component or a body component. The vertical acceleration frequency may be determined by applying a Fourier transform to an output signal from an accelerometer located on a sprung vehicle component. The Fourier transform may be expressed as follows: ys=∑k=0N−1ωksxk+1 where ω=e -2πi / n , k and s are indices, and x is the signal sample. The signal strength can be determined from the output of a vertical accelerometer and the following equation: P=1N∑n=0N−1x2[n] where P is the signal strength, N is the number of samples, and x[n] is the sample value at sample n. Method 500 proceeds to 506.

[0036] At 506, method 500 determines a vertical acceleration frequency and force of an unsprung vehicle mass, such as a chassis component or a body component (e.g., a wheel hub or suspension control arm). The vertical acceleration frequency may be determined by applying a Fourier transform to an output signal from an accelerometer located on an unsprung vehicle component. The signal strength and frequency are determined via the signal strength and Fourier transforms, as described at 504. Method 500 proceeds to 508.

[0037] At 508, method 500 estimates road roughness. In one example, method 500 estimates road roughness based on an output of the three-axis accelerometer. Specifically, average or integrated values ​​of vertical acceleration, longitudinal acceleration, and lateral acceleration are summed over a predetermined period of time to provide a single value that provides an indication of road roughness. The vertical, longitudinal, and lateral acceleration may be weighted to increase or decrease the influence of the respective axle via weighting factors for each of the respective axles. Thus, the estimate of road roughness is modified in response to the suspension mode in which the vehicle is operating. In one example, road roughness may be determined by the following equation: RR=Sm((Pv⋅W1)+(Pl⋅W2)+(Pt⋅W3)) Pchassis=W4⋅Pus+W5⋅Ps where RR is the road roughness, Sm is a multiplier for the suspension mode, Pv is the force output by the vertical accelerometer, Pl is the force output by the longitudinal accelerometer, Pt is the force output by the lateral accelerometer, W1 is a weighting factor for the vertical accelerometer, W2 is a weighting factor for the longitudinal accelerometer, and W3 is a weighting factor for the lateral accelerometer. The value of Sm can be different for different suspension modes, so changing the suspension mode can cause the actual total number of active cylinder modes to increase by increasing the road roughness value. For example, a sport suspension mode may have a higher damping ratio than a cruise suspension mode. Thus, the value of Sm can be adjusted so that the road roughness value is increased when operating the vehicle in sport suspension mode.Consequently, changing the vehicle's suspension mode may increase or decrease an actual total number of available cylinder modes depending on the road the vehicle is traveling on. Method 500 proceeds to 510 after the road roughness is estimated.

[0038] At 510, method 500 judges whether the road irregularity is greater than a first threshold. If so, the answer is yes and method 500 proceeds to 512. Otherwise, the answer is no and method 500 proceeds to 520 and Fig. 6.

[0039] At 520, method 500 judges whether a weighted sum of the vertical acceleration force of the unsprung vehicle suspension mass plus the vertical acceleration force of the sprung vehicle suspension mass is greater than a second threshold. For example, the method may judge whether P Fahrgestell = W4·P us +W5·P sis greater than a second threshold, where P Fahrgestell the weighted sum of the force of the vertical acceleration of the unsprung vehicle suspension component P us is, W4 is a weighting factor, P s is the vertical acceleration force of the sprung vehicle suspension component, and W5 is a weighting factor. If method 500 judges that the weighted sum of the vertical acceleration force of the unsprung vehicle suspension mass plus the vertical acceleration force of the sprung vehicle mass is greater than the second threshold, then the answer is yes, and method 500 proceeds to 522. Otherwise, the answer is no, and method 500 proceeds to 530.

[0040] If the weighted sum of the vertical acceleration force of the unsprung vehicle suspension mass and the vertical acceleration force of the sprung vehicle suspension mass is greater than a threshold, this may indicate that road-induced noise and vibration may be sufficient to mask noise and / or vibration emanating from engine operation with an increased number of deactivated cylinders. Thus, the actual total number of available cylinder modes may be increased.

[0041] At 530, method 500 judges whether a dominant frequency of acceleration of an unsprung suspension mass is greater than a third threshold and whether a vertical acceleration force of an unsprung mass of the vehicle suspension is greater than a fourth threshold. The unsprung mass may be an axle, a wheel hub, a suspension control arm, or another suspension component. The dominant frequency of acceleration may be the frequency at which the unsprung vehicle suspension mass has a greatest force or a force greater than a predetermined threshold. The vertical acceleration force of the unsprung mass may be determined as described at 506. The acceleration frequency of the unsprung mass may be determined as described at 506.If the acceleration frequency of the unsprung suspension mass is greater than the third threshold and if the vertical acceleration force of the unsprung mass is greater than a fourth threshold, the answer is yes and method 500 proceeds to 522. Otherwise, the answer is no and method 500 proceeds to 532. In some examples, method 500 may also require that the firing frequency of the engine in the available cylinder modes be greater than the unsprung and / or sprung frequency of the vehicle suspension components before increasing the number of available cylinder modes.

[0042] If the frequency of the unsprung vehicle suspension mass is greater than a threshold and the force of the vertical acceleration of the unsprung vehicle suspension mass is greater than a threshold, this may indicate that noise and vibration from the tire and vehicle suspension may be sufficient to mask noise and / or vibration emanating from engine operation with an increased number of deactivated cylinders. Thus, the actual total number of available cylinder modes may be increased. The accelerometer that senses the movement of the unsprung vehicle suspension may provide a better signal for estimating road and tire noise than the sprung vehicle suspension sensor.

[0043] At 522, method 500 judges whether an amount of time since the last cylinder mode change request to increase an actual total number of available cylinder modes is greater than a third threshold or whether an actual total number of cylinder events since a last request to increase an actual total number of available cylinder modes is greater than a fourth threshold. Cylinder events may include initiating combustion in a cylinder during a cylinder cycle by generating a spark in the cylinder (e.g., firings), opening or closing the intake or exhaust valves, injecting fuel into the cylinder, or other combustion-related events for the cylinder cycle. The time or the actual total number of cylinder events may begin to accumulate after a most recent or last request to increase the actual total number of active cylinder modes.By using an actual total amount of time following a request to increase an actual total number of available cylinder modes as a basis for increasing the actual total number of active cylinder modes, the amount of time to enable additional available cylinder modes can be standardized.

[0044] Alternatively, by using an actual total number of cylinders or combustion events after a last or most recent request to increase an actual total number of available cylinder modes as a basis for increasing the actual total number of active cylinder modes, the available cylinder modes may be enabled and increased earlier when the engine speed is higher, or the cylinder modes may be enabled or increased later when the engine speed is slower.Consequently, when engine operating conditions change such that a larger number of available cylinder modes is desired, the engine may be provided with a consistent number of combustion or cylinder events to stabilize it under the new operating conditions so that the actual total number of available cylinder modes is consistently engaged on an engine event basis, which may improve air-fuel control in the engine and reduce engine torque disturbances when one of the newly available cylinder modes is engaged.Conversely, if the number of available cylinder modes changes based on an amount of time since a request to change the number of available cylinder modes, the available cylinder modes may be increased or decreased inconsistently with respect to the number of cylinder or combustion events following a request to increase or decrease the actual total number of available cylinder modes. This may result in entry into a new cylinder mode before conditions for operating the engine with fewer active cylinders have stabilized, or in a cylinder mode being entered later, so the opportunity to improve fuel economy may be reduced.These conditions can be avoided by adjusting the actual total number of available cylinder modes in response to engine combustion or cylinder events since a last request to adjust the actual total number of available cylinder modes.

[0045] If method 500 judges that the amount of time since the last request to set the actual total number of available cylinder modes is greater than a threshold, or that an actual total number of cylinder or combustion events since a last request to set the actual total number of available cylinder modes is greater than a threshold, the answer is yes and method 500 proceeds to 524. Otherwise, the answer is no and method 500 proceeds to 526.

[0046] At 526, method 500 increments the amount of time since the request to change the actual total number of available cylinder modes. Alternatively, method 500 increments the actual total number of combustion events or cylinder events since the last request to change the actual total number of combustion events according to the actual total number of cylinder events or combustion events since the last request to change the actual total number of available cylinder modes. Method 500 also requires increasing the actual total number of available cylinder modes to improve vehicle fuel efficiency when vehicle occupants are less likely to notice cylinder deactivation. Method 500 proceeds to exit.

[0047] At 524, method 500 increases the actual total number of available cylinder modes. By increasing the actual total number of available cylinder modes, it may be possible to operate the engine with fewer active cylinders and additional cylinders deactivated. For example, a V8 engine may transition from one available cylinder mode (e.g., all cylinders active) to three available cylinder modes: all eight cylinders active; a first group of four cylinders active; and a second group of four cylinders active. The actual total number of available cylinder modes may be increased by increasing a speed range and a torque range in which the available cylinder modes are active (e.g., as shown in Fig. 3A and Fig. 3B). The engine is operated in one of the available cylinder modes included in the actual total number of available cylinder modes. The engine may be operated in one of the cylinder modes by enabling or disabling engine cylinders. Method 500 proceeds to exit.

[0048] At 532, method 500 returns to the base operating modes for a variable displacement engine cylinder. For example, the base cylinder mode for a V8 engine is when all engine cylinders are active and combusting air and fuel. A base cylinder mode for a six-cylinder engine may be when all six cylinders are active. A base cylinder mode for a four-cylinder engine may be when all four cylinders are active. The base cylinder modes are fewer than the actual total number of cylinder modes. The actual total number of available cylinder modes may be equal to or less than the actual total number of cylinder modes. In one example, the base cylinder modes for an engine are the cylinder modes that can be entered during all driving conditions without disturbing vehicle occupants or increasing the possibility of engine degradation. Method 500 proceeds to 562 after returning to the base cylinder modes.

[0049] At 534, method 500 sets a time since a last request to change the actual total number of active cylinder modes to a value of zero. Alternatively, method 500 sets an actual total number of cylinder events or combustion events since a last request to change the actual total number of active cylinder modes to a value of zero.

[0050] Thus, when a single value representing a road irregularity is not increased to a value greater than a first threshold, the actual total number of available cylinder modes may be increased to improve vehicle fuel efficiency based on a weighted sum of the force of vertical acceleration of an unsprung vehicle mass and the force of vertical acceleration of a sprung vehicle mass that is greater than a threshold.The acceleration of the unsprung vehicle mass may indicate road noise and time noise that may mask the noise of deactivated cylinders, so that even if the acceleration of the vehicle body is low due to the suspension operating mode, the actual total number of available cylinder modes may still be increased to increase engine fuel efficiency if the unsprung component noise masks the noise caused by the deactivated cylinders. Further, if the unsprung mass acceleration force from vehicle sensors is not available, method 500 may proceed directly from 532 to 510.

[0051] At 512, method 500 may remove cylinder modes from the available cylinder modes that have a firing frequency less than a dominant frequency of acceleration of the unsprung vehicle suspension mass. The dominant frequency may be the frequency at which the unsprung vehicle suspension mass exhibits greatest force. For example, if the unsprung vehicle mass has a dominant frequency of 10 Hz and operating the engine with one active cylinder during a cylinder stroke at the current engine speed provides 9 Hz, the cylinder mode with one active cylinder is removed from the available cylinder modes. In this way, the actual total number of available cylinder modes may be decreased. Method 500 proceeds to 514.

[0052] At 514, method 500 judges whether an amount of time since a last cylinder mode change request to increase an actual total number of available cylinder modes is greater than a third threshold or whether an actual total number of cylinder events since a last request to increase an actual total number of available cylinder modes is greater than a fourth threshold. Cylinder events may include initiating combustion in a cylinder during a cylinder cycle by generating a spark in the cylinder, opening or closing the intake or exhaust valves, injecting fuel into the cylinder, or other combustion-related events for the cylinder cycle. The time or the actual total number of cylinder events may begin to accumulate after a most recent or last request to increase the actual total number of active cylinder modes.By using an actual total amount of time after a request to increase an actual total number of available cylinder modes as a basis for increasing the actual total number of active cylinder modes, the amount of time to activate additional available cylinder modes can be standardized.

[0053] Alternatively, by using an actual total number of cylinder or combustion events after a request to increase an actual total number of available cylinder modes as a basis for increasing the actual total number of active cylinder modes, the available cylinder modes may be enabled and increased earlier when the engine speed is higher or the cylinder modes may be enabled or increased later when the engine speed is slower.Consequently, when engine operating conditions change such that a larger number of available cylinder modes is desired, the engine may be provided with a consistent number of combustion or cylinder events to stabilize it under the new operating conditions so that the actual total number of available cylinder modes is consistently engaged on an engine event basis, which may improve air-fuel control in the engine and reduce engine torque disturbances when one of the newly available cylinder modes is engaged.Conversely, if the number of available cylinder modes changes based on an amount of time since a request to change the number of available cylinder modes, the available cylinder modes may be increased or decreased inconsistently in terms of the number of cylinder or combustion events following a request to increase or decrease the actual total number of available cylinder modes. This may result in entry into a new cylinder mode before conditions for operating the engine with fewer active cylinders have stabilized, or in a cylinder mode being entered later, so the opportunity to improve fuel economy may be reduced.These conditions can be avoided by adjusting the actual total number of available cylinder modes in response to engine combustion or cylinder events since a last request to adjust the actual total number of available cylinder modes.

[0054] If method 500 judges that the amount of time since a last request to set the actual total number of available cylinder modes is greater than a threshold, or that an actual total number of cylinder or combustion events since a last request to set the actual total number of available cylinder modes is greater than a threshold, the answer is yes and method 500 proceeds to 516. Otherwise, the answer is no and method 500 proceeds to 517.

[0055] At 517, method 500 increments the amount of time since the request to change the actual total number of available cylinder modes. Alternatively, method 500 increments the actual total number of combustion events or cylinder events since the last request to change the actual total number of combustion events according to the actual total number of cylinder events or combustion events since the last request to change the actual total number of available cylinder modes. Method 500 also requires increasing the actual total number of available cylinder modes to improve vehicle fuel efficiency when vehicle occupants are less likely to notice cylinder deactivation. Method 500 proceeds to exit.

[0056] At 516, method 500 increases the actual total number of available cylinder modes. By increasing the actual total number of available cylinder modes, it may be possible to operate the engine with fewer active cylinders and additional cylinders deactivated. For example, a V8 engine may transition from one available cylinder mode (e.g., all cylinders active) to three available cylinder modes: all eight cylinders active; a first group of four cylinders active; and a second group of four cylinders active. The actual total number of available cylinder modes may be increased by increasing a speed range and a torque range in which the available cylinder modes are active (e.g., as shown in Fig. 3A and Fig. 3B). The engine is operated in one of the available cylinder modes included in the actual total number of available cylinder modes. The engine may be operated in one of the cylinder modes by enabling or disabling engine cylinders. Method 500 proceeds to exit.

[0057] Thus, the procedure Fig. 5 and Fig. 6 provides an engine control method, comprising: increasing, via a controller, the actual total number of available cylinder modes from a first actual total number of available cylinder modes to a second actual total number of available cylinder modes in response to an estimate of a roughness of a road exceeding a threshold; and operating, via the controller, an engine in a cylinder deactivation mode after increasing the actual total number of available cylinder modes. The method includes where the available cylinder modes include cylinder modes in which one or more cylinders are deactivated by adjusting fueling to the engine cylinders.The method further comprises entering the cylinder deactivation mode after counting an actual total number of engine events since a first estimate of road roughness exceeded a threshold, wherein the first estimate occurs after a last estimate of road roughness did not exceed the threshold.

[0058] The method includes where the actual total number of engine events is an actual total count of ignitions of air-fuel mixtures in the engine cylinders. The method includes where the actual total number of engine events is an actual total count of exhaust valve opening events. The method includes where increasing an actual total number of available cylinder modes includes increasing an actual total number of cylinder modes in which fewer than all cylinders of an engine are active. The method includes where road roughness is based on a vertical acceleration of a sprung vehicle mass.

[0059] The procedure from Fig. 5 and Fig. 6 also provides an engine control method comprising: increasing, via a controller, the actual total number of available cylinder modes from a first actual total number of available cylinder modes to a second actual total number of available cylinder modes in response to a transition from a first suspension control mode to a second suspension control mode; and operating, via the controller, an engine in a cylinder deactivation mode after the transition from the first suspension control mode to the second suspension control mode. The method further includes increasing the actual total number of available cylinder modes in further response to an estimate of road roughness. The method includes where the estimate of road roughness indicates that road roughness is increasing. The method includes where the first suspension mode includes a higher damping ratio than the second suspension mode.The method further includes decreasing, via the controller, an actual total number of available cylinder modes from the second actual total number of available cylinder modes to the first actual total number of available cylinder modes in response to a transition from the second suspension control mode to the first suspension control mode. The method includes where increasing an actual total number of available cylinder modes includes increasing an engine speed range at which the actual total number of available cylinder modes may be enabled. The method includes where increasing an actual total number of available cylinder modes includes increasing an engine torque range at which the actual total number of available cylinder modes may be enabled.

[0060] The procedure from Fig. 5 and Fig.6 also provides an engine control method comprising: increasing, via a controller, the actual total number of available cylinder modes from a first actual total number of available cylinder modes to a second actual total number of available cylinder modes in response to a frequency of vertical acceleration of a mass of a vehicle suspension and a force of vertical acceleration of the mass of the vehicle suspension; and operating, via the controller, an engine in a cylinder deactivation mode after increasing the actual total number of available cylinder modes. The engine control method further comprises increasing the actual total number of available cylinder modes in further response to an engine firing frequency being greater than the frequency of vertical acceleration of the mass. The engine control method includes the force of vertical acceleration of the mass being greater than a threshold.The engine control method further comprises decreasing the actual total number of available cylinder modes from the second actual total number of available cylinder modes to the first actual total number of available cylinder modes in response to the vertical acceleration force of the mass being less than the threshold. The engine control method includes where increasing an actual total number of available cylinder modes includes increasing an engine speed range at which the actual total number of available cylinder modes may be enabled. The engine control method includes where increasing an actual total number of available cylinder modes includes increasing an engine torque range at which the actual total number of available cylinder modes may be enabled.

[0061] It should be noted that the example control and estimation routines contained herein may be used with various engine and / or vehicle system configurations. The control methods and routines disclosed herein may be stored as executable instructions in non-transitory memory and may be executed by the control system, including the controller in combination with various sensors, actuators, and other engine components. The particular routines described herein may represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, and the like. As such, various illustrated acts, operations, and / or functions may be performed in the illustrated order, in parallel, or in some cases omitted.Likewise, the processing order is not required to achieve the features and advantages of the embodiments described herein, but is provided for ease of illustration and description. One or more of the illustrated acts, operations, and / or functions may be performed repeatedly, depending on the specific strategy employed. Furthermore, at least a portion of the described acts, operations, and / or functions may graphically represent code to be programmed into non-transitory memory of the computer-readable storage medium in the control system. The control acts may also transform the operating state of one or more sensors or actuators in the physical world when the described acts are performed by executing the instructions in a system including the various hardware components in combination with one or more controllers.

[0062] This concludes the description. Upon reading this description, those skilled in the art will be aware of various changes and modifications without departing from the spirit and scope of the description. For example, I3, I4, I5, V6, V8, V10, and V12 engines operating on natural gas, gasoline, diesel, or alternative fuel configurations could advantageously utilize the present description.

Claims

[1] Engine control method comprising: Increasing an actual total number of available cylinder modes from a first actual total number of available cylinder modes to a second actual total number of available cylinder modes via a controller in response to an estimate of roughness of a road exceeding a threshold; and Operating an engine, via the controller, in a cylinder deactivation mode after increasing the actual total number of available cylinder modes, wherein the cylinder deactivation mode is initiated after counting an actual total number of engine events after a first estimate of road roughness has exceeded a threshold, the first estimate being made after a last estimate of road roughness did not exceed the threshold. [2] The method of claim 1, wherein the available cylinder modes include cylinder modes in which one or more cylinders are deactivated by adjusting the fuel supply to the engine cylinders. [3] The method of claim 1, further comprising increasing the actual total number of available cylinder modes to the second actual total number of available cylinder modes via the controller in response to a transition from a first suspension control mode to a second suspension control mode. [4] The method of claim 3, wherein the actual total number of engine events is an actual total count of ignitions of air-fuel mixtures in the engine cylinders. [5] The method of claim 3, wherein the actual total number of engine events is an actual total count of exhaust valve opening events. [6] The method of claim 1, wherein increasing the actual total number of available cylinder modes includes increasing an actual total number of cylinder modes in which fewer than all cylinders of an engine are active. [7] The method of claim 1, wherein the roughness of the road is further based on a vertical acceleration of a sprung vehicle mass. [8] Engine control method, comprising: Increasing an actual total number of available cylinder modes from a first actual total number of available cylinder modes to a second actual total number of available cylinder modes via a controller in response to a transition from a first suspension control mode to a second suspension control mode; and Operating an engine via the controller in a cylinder deactivation mode after changing from the first suspension control mode to the second suspension control mode. [9] The method of claim 8, further comprising increasing the actual total number of available cylinder modes in further response to an estimate of road roughness. [10] The method of claim 9, wherein the estimate of road roughness indicates that the road roughness is increasing. [11] The method of claim 8, wherein the first suspension mode includes a higher damping ratio than the second suspension mode. [12] The method of claim 8, further comprising decreasing the actual total number of available cylinder modes from the second actual total number of available cylinder modes to the first actual total number of available cylinder modes via the controller in response to a transition from the second suspension control mode to the first suspension control mode. [13] The method of claim 8, wherein increasing the actual total number of available cylinder modes includes increasing an engine speed range at which the actual total number of available cylinder modes may be enabled. [14] The method of claim 8, wherein increasing the actual total number of available cylinder modes includes increasing an engine torque range at which the actual total number of available cylinder modes may be enabled. [15] Engine control method, comprising: Increasing an actual total number of available cylinder modes from a first actual total number of available cylinder modes to a second actual total number of available cylinder modes via a controller in response to a frequency of vertical acceleration of a mass of a vehicle suspension exceeding a threshold and a force of vertical acceleration of the mass of the vehicle suspension; and Operating an engine via the controller in a cylinder deactivation mode after increasing the actual total number of available cylinder modes.

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