Torque Converter Control for Variable Displacement Engines

Abstract

The present invention relates to torque converter control for a variable displacement engine. Systems and methods for operating an engine and a torque converter are presented. In one example, torque converter slip is adjusted via at least partially closing or opening a torque converter clutch in response to vehicle vibration. Vehicle vibration may be based on road surface conditions and the actual total number of operating cylinders of the engine.

Description

Technical Field

[0001] The present invention relates to a system and method for operating an engine and a torque converter under conditions where one or more cylinders of the engine can be temporarily deactivated to improve engine fuel economy. The method and system provide a way to provide a desired level of fuel economy and a desired level of vehicle noise. Background Art

[0002] The vehicle may also include one or more cylinders of an engine that can be temporarily deactivated to improve the fuel economy of the vehicle. One or more cylinders may be deactivated by stopping the supply of fuel and spark to the deactivated cylinders. In addition, the airflow into and out of the deactivated cylinders may be prevented or at least significantly reduced by closing the intake valve and throttle of the deactivated cylinders. The engine may also be mechanically coupled to a transmission including a torque converter. The torque converter allows the engine to rotate without the vehicle having to move and the engine need not be completely separated from the transmission. In addition, the impeller of the torque converter may be locked to the turbine of the torque converter to increase the efficiency of the drive train; however, locking the torque converter may increase the noise, vibration and discomfort (NVH) of the drive train. When the cylinders are deactivated and when the torque converter is locked, the drive train will be at a higher efficiency, but the drive train vibration will be greater than what is expected under such conditions. Therefore, it would be desirable to provide a method for providing a higher level of drive train efficiency without the vehicle occupants having to endure an undesirable level of vehicle vibration and noise. Summary of the invention

[0003] The inventors herein have recognized the limitations noted above and have developed an engine control method comprising increasing, via a controller, an actual total number of operating cylinders from a first actual total number of operating cylinders to a second actual total number of operating cylinders in response to a slip of a torque converter exceeding a threshold value, wherein the threshold value is a function of a fuel benefit and a fuel penalty.

[0004] By increasing the actual total number of operating cylinders in response to torque converter slip exceeding a threshold value, the threshold value being a function of fuel benefit and fuel deficiency, it may be possible to provide a technical effect of operating the engine in a cylinder deactivation mode and controlling torque converter slip so that driveline efficiency is high and vehicle occupants are not disturbed by driveline noise. For example, an eight-cylinder engine may be changed from a four-cylinder operating mode to a six- or eight-cylinder operating mode when torque converter slip exceeds a threshold value indicating that increasing the actual total number of operating cylinders may be more effective in controlling NVH and operating the driveline efficiently.

[0005] The present invention may provide several advantages. Specifically, the solution may provide a vehicle with improved fuel economy and reduced NVH. In addition, the solution may reduce the likelihood of disturbing the vehicle's occupants when cylinders are deactivated. In addition, the solution provides a useful way to resolve whether it is more beneficial to increase torque converter slip to improve driveline NVH or to activate additional cylinders to improve NVH.

[0006] The above advantages and other advantages and features of the present invention will be apparent when referring to the following description alone or in conjunction with the accompanying drawings.

[0007] It should be understood that the above summary is provided to introduce some concepts in a simplified form, which are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is solely defined by the appended claims. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages mentioned above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The advantages described herein will be more fully understood by reading the examples of embodiments (also referred to herein as detailed description) when considered alone or with reference to the accompanying drawings, in which:

[0009] Figure 1 It is a schematic diagram of the engine;

[0010] Figure 2A and 2B is a schematic diagram of an example engine configuration;

[0011] Figure 3 Shown include Figure 1 A schematic diagram of an example powertrain or driveline of an engine;

[0012] Figure 4 is a graph of an example manner of adjusting the total actual number of active or operating cylinders in response to torque converter slip;

[0013] Figures 5A-5C Example vehicles and suspension components are shown; and

[0014] Figure 6 A flow chart of an example method for controlling a vehicle powertrain is shown. DETAILED DESCRIPTION

[0015] The present invention is directed to improving engine operation and vehicle drivability during conditions where engine cylinders can be deactivated to improve vehicle fuel efficiency. Figure 1-2BThe cylinders of the engine shown in can be selectively deactivated (e.g., not combusting air and fuel) to improve engine fuel efficiency. The engine cylinders can also be reactivated (e.g., combusting air and fuel) to improve engine power output and reduce engine and vehicle chassis vibration. The engine can be included in Figure 3 In the vehicle powertrain shown in FIG. Figure 4 As shown in FIG. 1 , engine cylinders can be activated and deactivated based on torque converter slip. The engine and vehicle driveline can be incorporated into a Figure 5A-5C In the vehicle with the suspension shown in FIG. Figure 6 The method can adjust the engine and transmission operation of a vehicle to improve vehicle fuel efficiency and drivability.

[0016] Reference Figure 1 Internal combustion engine 10 is controlled by electronic engine controller 12, wherein engine 10 comprises a plurality of cylinders. Figure 1 1 and 2. One cylinder among a plurality of cylinders is shown in FIG. 1. Engine 10 includes combustion chamber 30 and cylinder wall 32, wherein piston 36 is disposed in said cylinder wall 32 and connected to crankshaft 40. Combustion chamber 30 is shown as being in communication with intake manifold 44 and exhaust manifold 48 via respective intake valve 52 and exhaust valve 54. Each intake valve and exhaust valve may be operated by intake cam 51 and exhaust cam 53. The position of intake cam 51 may be determined by intake cam sensor 55. The position of exhaust cam 53 may be determined by exhaust cam sensor 57. Intake cam 51 and exhaust cam 53 may be moved relative to crankshaft 40. The intake valve may be deactivated and maintained in a closed state via intake valve deactivation mechanism 59. The exhaust valve may be deactivated and maintained in a closed state via exhaust valve deactivation mechanism 58.

[0017] Fuel injector 66 is shown as being positioned to inject fuel directly into cylinder 30, which is referred to as direct injection by those skilled in the art. Alternatively, fuel can be injected into the intake port, which is referred to as port injection by those skilled in the art. Fuel injector 66 delivers liquid fuel in proportion to the pulse width of the signal from controller 12. Fuel is delivered to fuel injector 66 by fuel system 175, which includes a tank and a pump. In addition, intake manifold 44 is shown as being connected to an optional electronic throttle 62 (e.g., a butterfly valve), which adjusts the position of throttle plate 64 to control the air flow from air filter 43 and intake device 42 to intake manifold 44. Throttle 62 regulates the air flow from air filter 43 in engine intake device 42 to intake manifold 44. In some examples, throttle 62 and throttle plate 64 can be positioned between intake valve 52 and intake manifold 44, so that throttle 62 is an intake port throttle.

[0018] Distributorless ignition system 88 provides an ignition spark to combustion chamber 30 via spark plug 92 in response to controller 12. Universal Exhaust Gas Oxygen (UEGO) sensor 126 is shown coupled to exhaust manifold 48 upstream of catalytic converter 70. Alternatively, a two-state exhaust gas oxygen sensor may be substituted for UEGO sensor 126.

[0019] In one example, converter 70 can include multiple catalyst bricks. In another example, multiple emission control devices, each having multiple bricks, can be used. In one example, converter 70 can be a three-way type catalyst.

[0020] The controller 12 Figure 1 1 is shown as a conventional microcomputer including: a microprocessing unit (CPU) 102, input / output ports (I / O) 104, read-only memory (ROM) 106 (e.g., non-temporary memory), random access memory (RAM) 108, a keep alive memory (KAM) 110, and a conventional data bus. Controller 12 is shown receiving various signals from sensors coupled to engine 10, including, in addition to those previously discussed, engine coolant temperature (ECT) from temperature sensor 112 coupled to cooling sleeve 114; position sensor 134 coupled to accelerator pedal 130 for sensing force applied by human operator 132; measurement of engine manifold pressure (MAP) from pressure sensor 122 coupled to intake manifold 44; engine position sensor from Hall effect sensor 118 sensing position of crankshaft 40; measurement of air mass entering the engine from sensor 120; brake pedal position from brake pedal position sensor 154 when human operator 132 acts on brake pedal 150; and measurement of throttle position from sensor 58. Barometric pressure may also be sensed (sensor not shown) for processing by controller 12. In a preferred aspect of the present invention, engine position sensor 118 produces a predetermined number of equally spaced pulses per revolution of the crankshaft from which engine speed (RPM) can be determined. Controller 12 may receive input from a human / machine interface 115 (eg, a push button or a touch screen display).

[0021] In some examples, the engine can be coupled to an electric motor / battery system in a hybrid vehicle. Additionally, in some examples, other engine configurations can be employed, such as a diesel engine.

[0022] During operation, each cylinder within engine 10 typically undergoes four stroke cycles: the cycle includes an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke. Generally speaking, during the intake stroke, 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 where piston 36 is near the bottom of the cylinder and at the end of its stroke (e.g., when combustion chamber 30 is at its largest volume) is typically referred to by those of skill in the art as bottom dead center (BDC). During the compression stroke, 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 position where piston 36 is at the end of its stroke and closest to the cylinder head (e.g., when combustion chamber 30 is at its smallest volume) is typically referred to by those of skill in the art as top dead center (TDC). In a process hereinafter referred to as injection, fuel is introduced into the combustion chamber. In a process hereinafter referred to as ignition, the injected fuel is ignited by known ignition means (such as spark plug 92), resulting in combustion. During the expansion stroke, the expanding gases push piston 36 back to BDC. Crankshaft 40 converts the piston motion into rotational torque of the rotating 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. Note that the above is shown only as an example, and the intake and exhaust valve opening and / or closing timings may be varied, such as to provide positive or negative valve overlap, late intake valve closing, or various other examples.

[0023] Now refer to Figure 2A , shows a first configuration of the engine 10. The 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. Therefore, the first configuration is a V8 engine including two cylinder banks. All cylinder operation may be a first cylinder operation mode.

[0024] Under selected conditions, one or more of the cylinders 210 can be deactivated by stopping the flow of fuel to the deactivated cylinders. In addition, the airflow to the deactivated cylinders can be stopped by closing and maintaining the intake and exhaust valves of the deactivated cylinders. The engine cylinders can be deactivated in a variety of forms to provide the desired actual total number of activated or deactivated cylinders. For example, cylinders 2, 3, 5, and 8 can be deactivated to form a first type of deactivated cylinder and a second cylinder operating mode. Alternatively, cylinders 1, 4, 6, and 7 can be deactivated to form a second type of deactivated cylinder and a third cylinder operating mode. In another example, cylinders 2 and 8 can be deactivated to form a third type of deactivated cylinder and a fourth cylinder operating mode. In another example, cylinders 3 and 5 can be deactivated to form a fourth type of deactivated cylinder and a fifth cylinder operating mode. In this example, five cylinder operating modes are provided; however, additional or fewer cylinder operating modes can be provided. If the engine condition is such that the engine can be operated in any of the five described cylinder modes, the engine can be described as having five available cylinder operating modes. In this example, if two of the five operating modes of the engine are not available, the engine can be described as having three available operating modes. The engine always has one available cylinder operating mode (e.g., all cylinders active and burning air and fuel). Of course, depending on the engine configuration, the actual total number of available operating modes may be more or less than five.

[0025] Now refer to Figure 2B , shows a second configuration of the engine 10. The engine 10 includes one cylinder bank 206. The cylinder bank 206 includes cylinders 210 numbered 1-4. Therefore, the first configuration is an I4 engine including one cylinder bank. For this engine configuration, all cylinder operation may be a first cylinder operation mode.

[0026] Similar to the first configuration, one or more of the cylinders 210 can be deactivated via stopping the flow of fuel to the deactivated cylinders. In addition, the airflow to the deactivated cylinders can be stopped via closing and maintaining the intake and exhaust valves of the deactivated cylinders. The engine cylinders can be deactivated in a variety of forms to provide the desired actual total number of activated or deactivated cylinders. For example, cylinders 2 and 3 can be deactivated to form the first and second cylinder operating modes of the deactivated cylinders. Alternatively, cylinders 1 and 4 can be deactivated to form the second and third cylinder operating modes of the deactivated cylinders. In another example, cylinder 2 can be deactivated to form the third and fourth cylinder operating modes of the deactivated cylinders. In another example, cylinder 3 can be deactivated to form the fourth and fifth cylinder operating modes of the deactivated cylinders. In this example, if the engine condition is such that the engine can operate under any of the five cylinder modes described, the engine can be described as having five available cylinder operating modes. If two of the five operating modes of the engine are unavailable, the engine can be described as having three available operating modes. The engine always has one available cylinder operating mode (eg, all cylinders active and burning air and fuel). Of course, depending on the engine configuration, the actual total number of available operating modes may be more or less than five.

[0027] In other examples, different cylinder configurations may be provided. For example, the engine may be a V6 engine or a V10 engine. Different engine configurations may also have different numbers of cylinder operating modes.

[0028] Now refer to Figure 3 , a block diagram of a vehicle 325 including a powertrain or driveline 300 is shown. Figure 3 The powertrain system includes Figure 1 10 is shown in FIG. 10. The powertrain system 300 is shown to include a vehicle system controller 355, an engine controller 12, a transmission controller 354, and a brake controller 350. The controllers may communicate via a controller area network (CAN) 399. Each of the controllers may provide the following information to the other controllers: such as torque output limits (e.g., torque outputs of the device or component being controlled that will not be exceeded), torque input limits (e.g., torque inputs of the device or component being controlled that will not be exceeded), torque outputs of the device being controlled, sensor and actuator data, diagnostic information (e.g., information about a degraded transmission, information about a degraded engine, information about a degraded motor, information about a degraded brake). In addition, the vehicle system controller 355 may provide commands to the engine controller 12, the transmission controller 354, and the brake controller 350 to implement driver input requests and other requests based on vehicle operating conditions.

[0029] In other examples, the division of control of the powertrain devices may be different than in Figure 3 For example, a single controller may replace the vehicle system controller 355, the engine controller 12, the transmission controller 354, and the brake controller 350. Alternatively, the vehicle system controller 355 and the engine controller 12 may be a single unit, while the transmission controller 354 and the brake controller 350 are separate controllers.

[0030] In this example, the powertrain 300 can be powered by the engine 10. In addition, the torque of the engine 10 can be adjusted via a torque actuator 304 (such as a fuel injector, a throttle, etc.). The engine output torque can be transmitted to the impeller 385. The torque converter 306 includes a turbine 386 to output the torque to the input shaft 370. The input shaft 370 mechanically couples the torque converter 306 to the automatic transmission 308. The torque converter 306 also includes a torque converter bypass locking clutch 312 (TCC). When the TCC is locked, the torque is transferred directly from the impeller 385 to the turbine 386. The TCC is electrically operated by the controller 12. Alternatively, the TCC can be hydraulically locked. In one example, the torque converter can be referred to as a component of the transmission.

[0031] When the torque converter lockup clutch 312 is fully disengaged, the torque converter 306 transmits the engine torque to the automatic transmission 308 via the fluid transfer between the torque converter turbine 386 and the torque converter impeller 385, thereby achieving torque multiplication. In contrast, when the torque converter lockup clutch 312 is fully engaged, the engine output torque is directly transferred to the input shaft 370 of the transmission 308 via the torque converter clutch. Alternatively, the torque converter lockup clutch 312 can be partially engaged, thereby enabling the amount of torque directly transmitted to the transmission to be adjusted. The transmission controller 354 can be configured to adjust the amount of torque transmitted through the torque converter 312 by adjusting the torque converter lockup clutch in response to various engine operating conditions or based on the driver's engine operation requirements.

[0032] The automatic transmission 308 includes a gear clutch (e.g., gear 1-10) 311 and a forward clutch 310 for activating a gear 313 (e.g., gear 1-10). The automatic transmission 308 is a fixed ratio transmission. The gear clutch 311 and the forward clutch 310 can be selectively engaged to change the ratio of the actual total number of revolutions of the input shaft 370 to the actual total number of revolutions of the wheel 316. The gear clutch 311 can be engaged or disengaged via adjusting the fluid supplied to the clutch via the shift control solenoid valve 309. The torque output from the automatic transmission 308 can also be transmitted to the wheel 316 to propel the vehicle via the output shaft 360. Specifically, before the output drive torque is transmitted to the wheel 316, in response to the vehicle travel condition, the automatic transmission 308 can transfer the input drive torque at the input shaft 370. The transmission controller 354 selectively activates or engages the TCC 312, the gear clutch 311 and the forward clutch 310. The transmission controller also selectively deactivates or disengages the TCC 312 , the range clutch 311 , and the forward clutch 310 .

[0033] Additionally, frictional forces may be applied to wheels 316 by engaging friction wheel brakes 318. In one example, friction wheel brakes 318 may be engaged in response to the driver pressing their foot on a brake pedal (not shown) and / or in response to instructions within brake controller 350. Additionally, brake controller 350 may apply brakes 318 in response to information from vehicle system controller 355 and / or by request. In the same manner, frictional forces at wheels 316 may be reduced by disengaging friction wheel brakes 318 in response to the driver releasing their foot from the brake pedal, brake controller instructions, and / or vehicle system controller instructions and / or information. For example, vehicle brakes may apply frictional forces to wheels 316 via controller 350 as part of an automatic engine stop procedure.

[0034] In response to a request to accelerate the vehicle 325, the vehicle system controller may obtain a driver requested torque or power level from an accelerator pedal or other device. The vehicle system controller 355 then distributes the requested driver requested torque to the engine. The vehicle system controller 355 requests engine torque from the engine controller 12. If the engine torque is less than the transmission input torque limit (e.g., the threshold is not exceeded), the torque is delivered to the torque converter 306, which then transmits at least a small portion of the requested torque to the transmission input shaft 370. In response to a shift schedule and a TCC lock schedule that may be based on the input shaft torque and vehicle speed, the transmission controller 354 selectively locks the torque converter clutch 312 and engages the gear via the gear clutch 311.

[0035] Accordingly, torque control of the various powertrain components may be monitored by vehicle system controller 355 , with local torque control for engine 10 , transmission 308 , and brakes 318 provided via engine controller 12 , transmission controller 354 , and brake controller 350 .

[0036] As an example, the engine torque output may be controlled and / or limited by adjusting a combination of spark timing, fuel pulse width, fuel pulse timing, and / or air charge, by controlling throttle opening and / or valve timing, valve lift, and boost for a turbo or supercharged engine. In the case of a diesel engine, the controller 12 may control the engine torque output by controlling a combination of fuel pulse width, fuel pulse timing, and air charge. In any case, engine control may be performed on a cylinder-by-cylinder basis to control the engine torque output.

[0037] The transmission controller 354 receives the transmission input shaft position via the position sensor 371. The transmission controller 354 can convert the transmission input shaft position to the input shaft speed by differentiating the signal from the position sensor 371 or counting the number of pulses of known angular distance within a predetermined time. The transmission controller 354 can receive the transmission output shaft torque from the torque sensor 372. Alternatively, the sensor 372 can be a position sensor or a torque and position sensor. If the sensor 372 is a position sensor, the controller 354 can count the shaft position pulses within a predetermined time to determine the transmission output shaft speed. The transmission controller 354 can also differentiate the transmission output shaft speed to determine the transmission output shaft acceleration. The transmission controller 354, the engine controller 12 and the vehicle system controller 355 can also receive other transmission information from the sensor 377, which can include but is not limited to vehicle situational awareness sensors (e.g., cameras, microphones and distance detection systems (including radar, laser and ultrasonic transmission and sensing devices)), transmission hydraulic pressure sensors (e.g., gear clutch fluid pressure sensors) and ambient temperature sensors.

[0038] The brake controller 350 receives wheel speed information via the wheel speed sensor 321 and a brake request from the vehicle system controller 355. The brake controller 350 may also directly receive the wheel speed information from the vehicle system controller 355. Figure 1 399 or receives brake pedal position information via the brake pedal sensor 154 shown in FIG. 394 or via CAN 399. The brake controller 350 may provide braking in response to wheel torque commands from the vehicle system controller 355. The brake controller 350 may also provide anti-skid and vehicle stability braking to improve vehicle braking and stability.

[0039] therefore, Figure 1-Figure 3 A system of a vehicle system is provided, comprising: an accelerometer coupled to a vehicle; an engine coupled to the vehicle; and a controller including executable instructions stored in a non-transitory memory to adjust slip of a torque converter in response to a frequency of vertical acceleration of a mass of a suspension of the vehicle and a power of vertical acceleration of the mass of the suspension of the vehicle. The system includes, wherein adjusting slip of the torque converter includes at least partially releasing a torque converter clutch. The system includes, wherein adjusting slip of the torque converter includes at least partially closing a torque converter clutch. The system includes, wherein the accelerometer is coupled to an unsprung vehicle suspension component. The system further includes additional instructions to adjust an actual total number of operating cylinders in response to the frequency of vertical acceleration of the mass. The system includes, wherein adjusting slip of the torque converter in response to the frequency includes decreasing slip of the torque converter in response to an increase in the frequency.

[0040] Now refer to Figure 4 , a graph of a predictive example manner of adjusting the actual total number of activated or operating engine cylinders (e.g., cylinders burning air and fuel) and the actual total number of deactivated or non-operating engine cylinders. The graph represents the manner of controlling or operating the powertrain at a constant driver requested torque and vehicle speed to simplify the concepts for presentation, but the method can be extended to a wide range of vehicle speeds and engine loads.

[0041] The vertical axis represents torque converter slip (e.g., the difference between the torque converter impeller speed and the torque converter turbine speed), and torque converter slip increases in the direction of the vertical axis arrow. Torque converter efficiency can decrease as torque converter slip increases. Torque converter slip can be reduced by at least partially closing the torque converter clutch. By at least partially closing the torque converter clutch, at least a portion of the torque difference between the torque converter impeller and the torque converter turbine can be transferred between the torque converter impeller and the torque converter turbine via a friction element (e.g., the torque converter clutch). Conversely, torque converter slip can be increased by at least partially opening the torque converter clutch so that less torque can be transferred between the torque converter impeller and the torque converter turbine via the torque converter clutch. The horizontal axis represents vehicle fuel economy, and vehicle fuel economy increases from the left side of the figure to the right side of the figure. Curve 402 represents the vehicle fuel economy when the vehicle is operating with all of its cylinders active or operating (e.g., eight cylinders) (a third actual total number of active or operating engine cylinders). Curve 404 represents the vehicle fuel economy when the vehicle is operating with less than all of its cylinders active or operating (e.g., six cylinders) (a second actual total number of active or operating engine cylinders). Curve 406 represents the vehicle fuel economy when the vehicle is operating with less than all of its cylinders active or operating (e.g., four cylinders) (a first actual total number of active or operating engine cylinders). The actual total number of active engine cylinders that provides curve 406 is less than the actual total number of active engine cylinders that provides curve 404. Additionally, the actual total number of active engine cylinders that provides curve 404 is less than the actual total number of active engine cylinders that provides curve 402.

[0042] Thus, it can be observed that, at a specific vehicle speed and load, operating the engine with fewer cylinders in order to provide the desired driver demand torque reduces vehicle fuel consumption. In addition, activating additional engine cylinders reduces vehicle fuel economy. By operating the engine with fewer activated cylinders, the efficiency of the operating cylinders can be increased, and engine pumping losses can be reduced. This is shown by curve 402 on the left side of curve 404 and by curve 404 on the left side of curve 406. However, because the engine cylinders ignite or burn less frequently at a given engine speed than when the engine is operating with a larger number of active cylinders at the same engine speed, engine noise and vibration will increase. Increased engine noise and vibration can be transferred to the vehicle chassis, where the vehicle occupants will notice it. If the torque converter of the transmission is allowed to slip, less noise and vibration can be transferred to the vehicle chassis, but increased torque converter slip reduces vehicle fuel efficiency, as can be observed by curves 402, 404 and 406 tilted toward the vertical axis, thereby indicating a decrease in vehicle fuel economy as torque converter slip increases. Thus, the present invention provides a way to determine how many cylinders should be activated and what amount of torque converter slip can be provided to allow the vehicle to operate efficiently and with less likelihood of disturbing vehicle occupants by taking into account the fuel economy benefits of deactivating cylinders and the fuel economy disadvantages of increasing torque converter slip to reduce vehicle NVH.

[0043] Lead 405 shows the distance between curve 406 and curve 404. This distance represents the vehicle fuel economy benefit of operating the vehicle with a first actual total number of active cylinders (e.g., curve 406) and operating the vehicle with a second actual total number of active cylinders (e.g., curve 404) when the torque converter clutch is locked. The amount of torque converter slip at the horizontal axis is substantially zero (e.g., within 20 RPM of zero slip when the torque converter clutch is fully closed or the torque converter impeller speed is within 20 RPM of the torque converter turbine speed). Similarly, lead 403 shows the distance between curve 402 and curve 404. This distance represents the vehicle fuel economy benefit of operating the vehicle with a second actual total number of active cylinders (e.g., curve 404) and operating the vehicle with a third actual total number of active cylinders (e.g., curve 402) when the torque converter clutch is locked. Therefore, to achieve maximum vehicle fuel economy, it would be desirable to operate the engine at point 420 at the current driver demand torque and vehicle speed, where the actual total number of active engine cylinders corresponds to those depicted by curve 406 with the torque converter fully closed.

[0044] When the vehicle is traveling on a smooth road, the vehicle occupants may be disturbed by operating the vehicle with the actual total number of active engine cylinders represented by curve 406 because the road noise is low and the road noise may not be sufficient to generate engine and driveline NVH via operating the engine with a lesser actual total number of activated engine cylinders. However, if the torque converter slip is increased in the direction indicated by arrow 422, the vehicle occupants will be less aware of the NVH originating from the driveline. Therefore, arrow 422 indicates the fuel economy disadvantage associated with reducing driveline and vehicle NVH via torque converter slip. Conversely, if the driveline is operated at point 420 on a rough road where the road noise can mask the driveline noise, the vehicle occupants will be less aware of the NVH originating from the driveline.

[0045] Different roads may have different road noise levels depending on the road material (e.g., concrete, asphalt, or gravel) and the road surface conditions (e.g., bumps, discontinuities, etc.). Therefore, depending on the conditions of the road on which the vehicle is traveling, it may be desirable to adjust the torque converter slip to change from point 420 to point 410. However, increasing the torque converter slip may provide a return to a point where increasing the torque converter slip in terms of vehicle fuel economy outweighs the vehicle fuel economy advantage of running the engine with fewer engine cylinders. Therefore, operating point 410 represents a threshold value where the actual total number of active engine cylinders may be increased and the actual total number of available cylinder modes may be reduced when further driveline NVH reduction is desired due to road conditions and / or vehicle vibrations. The operating point or threshold 410 also indicates where the fuel benefit of running the engine with fewer cylinders is exhausted by the fuel disadvantage of increasing the torque converter slip via the trajectory from point 420 to point 410. Thus, threshold 410 is a function of or based on fuel benefit 405 and the fuel deficit between point 420 and point 410. Arrow 424 shows that the engine operating state can be changed from operating the engine with fewer cylinders to a greater number of cylinders to further reduce driveline and vehicle NVH. Therefore, if it is desired to take additional measures to reduce the likelihood of disturbing vehicle occupants due to driveline NVH, additional cylinders can be activated so that the engine moves from point 410 where fewer engine cylinders are activated to point 425 where a greater actual total number of engine cylinders are activated. In addition, when the driveline changes from the operating conditions at 410 to the operating conditions at 425, the amount of torque converter slip is reduced. Therefore, the fuel economy deficit caused by increasing torque converter slip above the level shown at point 410 can be mitigated by changing the driveline operating conditions at point 425.

[0046] If road conditions change further, such as when the vehicle begins traveling on a smoother road (e.g., a brushed concrete road) after traveling on a rougher road (e.g., a gravel road), the driveline NVH can be further reduced to make it less noticeable to vehicle occupants by increasing torque converter slip while the engine is operating with a total number of cylinders active corresponding to curve 404. Specifically, the driveline operating conditions can be adjusted via adjusting the torque converter slip as indicated by arrow 426. If road conditions change sufficiently that the torque converter slip is adjusted to the level of operating point 412, additional engine cylinders can be activated because reducing NVH via further increasing torque converter slip becomes less fuel efficient than increasing the actual total number of active cylinders and reducing the torque converter slip to the condition shown at point 430. Therefore, the vehicle operating conditions can be adjusted from point 412 to point 430 as indicated by arrow 428. The operating point or threshold 412 also indicates where the fuel benefit of operating the engine with fewer cylinders (e.g., curve 404) is depleted by the fuel deficit of increasing torque converter slip via the trajectory from point 425 to point 415. Thus, threshold 412 is a function of or based on fuel benefit 403 and the fuel deficit between points 425 and 412. If additional powertrain adjustments are desired to reduce vehicle occupant exposure to powertrain NVH, torque converter slip may be increased in the direction of arrow 432.

[0047] Thus, operating points 420, 410, 425, 412, and 430 correspond to the amount of vehicle NVH that may be desired for selected vehicle operating conditions, such as operating the vehicle in a cylinder deactivation mode on smoother or rougher roads. The powertrain operating conditions may be adjusted so that the powertrain operates at or between operating points along curves 406, 404, and 402 in response to vehicle operating conditions, such as road surface conditions. Additionally, by considering the fuel benefits of operating fewer or more engine cylinders and increasing or decreasing powertrain efficiency and fuel economy via torque converter slip, powertrain NVH may be tailored to road surface conditions such that vehicle fuel economy may be at a desired level even if powertrain NVH is reduced to accommodate road surface conditions.

[0048] Now refer to Figure 5A , shows an example vehicle 502 in which the engine 10 may be located. The vehicle 502 includes a three-axis accelerometer 504 that can sense sprung chassis vertical acceleration, longitudinal acceleration, and lateral acceleration. The vertical, longitudinal, and lateral directions are indicated via the illustrated coordinate system. Sprung chassis components are components that are supported via suspension springs. Thus, the vehicle body 505 is a sprung mass, while the wheels 590 are unsprung masses. Figure 5B and5C Additional examples of sprung and unsprung masses are shown.

[0049] Figure 5B An example chassis suspension 510 for vehicle 502 or a similar vehicle is shown. A tire 512 is mounted to a wheel (not shown), and the wheel is mounted to a hub 508. The hub 508 is mechanically coupled to a lower control arm 519 and an upper control arm 520. The upper control arm 520 and the lower control arm 519 can pivot about a chassis support 502, which can be part of the body of the vehicle. A spring 515 is coupled to the chassis support 502 and the lower control arm 519 so that the spring 515 supports the chassis support 502. The hub 508, the upper control arm 520, and the lower control arm 519 are unsprung because they are not supported by the spring 515 and they move according to the surface of the road the vehicle is traveling on. A damper (not shown) can accompany the spring 515 to provide a second order system. The accelerometer 509 can sense the vertical acceleration of the unsprung chassis components, while the accelerometer 535 can sense the vertical acceleration of the sprung chassis components. Accelerometer 509 may provide a more direct indication of how unsprung chassis components are responding to the road surface. Accelerometer 535 may provide an indication of how sprung chassis components are responding to road surface conditions that affect the sprung chassis components. Additionally, accelerometer 535 may provide an indication of engine vibrations associated with cylinder deactivation that affect the sprung chassis components and may affect vehicle occupants.

[0050] The output of accelerometer 509 can provide a basis for determining how much improvement in road related noise a vehicle occupant will observe due to the movement of unsprung chassis components and tire noise, compared to the output of accelerometer 435, which senses the acceleration of the sprung mass. This can be particularly true if the suspension springs and / or dampers have been replaced with different components or if they are in a degraded condition. The output of accelerometer 535 can sense engine vibrations and accelerations due to the suspension springs and dampers that are not inferred or sensed by accelerometer 509.

[0051] Figure 5CAnother example chassis suspension 550 for vehicle 502 or a similar vehicle is shown. Tires 512 are mounted to wheels (not shown), and wheels are mounted to hubs 557. Hubs 557 are mechanically coupled to axles 561. Springs 551 are coupled to chassis 555 and axles 561. Hubs 508 and axles 561 are unsprung in that they are not supported by springs 551 and they move according to the surface of the road the vehicle is traveling on. A damper (not shown) may accompany springs 551 to provide a second order system. Accelerometers 552 may sense the vertical acceleration of unsprung chassis components, while accelerometers 559 may sense the vertical acceleration of sprung chassis components. Accelerometers 552 may provide a more direct indication of how unsprung chassis components are responding to the road surface. Accelerometers 559 may provide an indication of how sprung chassis components are responding to road surface conditions that affect sprung chassis components. Additionally, accelerometer 559 may provide an indication of engine vibrations associated with cylinder deactivation that affect sprung chassis components and may affect vehicle occupants.

[0052] The output of accelerometer 552 can provide a basis for determining how much improvement in road related noise a vehicle occupant will observe due to the movement of unsprung chassis components and tire noise, compared to accelerometer 559, which senses the acceleration of the sprung mass. This can be particularly true if the suspension springs and / or dampers have been replaced with different components or if they are in a degraded condition. The output of accelerometer 559 can sense engine vibrations and accelerations due to the suspension springs and dampers that are not inferred or sensed by accelerometer 552.

[0053] Now refer to Figure 6 , an example flow chart of a method for operating a vehicle powertrain is shown. Figure 6 The method can be incorporated into Figure 1-Figure 3 within the system and can be used with Figure 1-Figure 3 In addition, Figure 6 At least part of the method may be stored as executable instructions in a non-transitory memory, while other parts of the method may be executed by transforming the operating state of a device or actuator in the physical world via a controller.

[0054] At 602, method 600 determines a mode of a suspension of a vehicle. In one example, a vehicle may have two or more modes, including track (e.g., hard or non-compliant suspension), sport (e.g., medium hardness suspension), and cruise (e.g., non-compliant suspension). The suspension mode may be determined via a user input device. Method 600 proceeds to 604.

[0055] At 604, method 600 determines the vertical acceleration frequency and power of a sprung vehicle mass, such as a chassis component or a body component. The vertical acceleration frequency may be determined via applying a Fourier transform to an output signal of an accelerometer located on the sprung vehicle component. The Fourier transform may be represented as:

[0056]

[0057] where ω = e -2πi / n , k and s are exponents, and x is a signal sample. The signal power can be determined from the output of the vertical accelerometer and the following formula:

[0058]

[0059] Where P is the signal power, N is the number of samples, and x[n] is the sample value at sample n. Method 600 proceeds to 606.

[0060] At 606, method 600 determines the vertical acceleration frequency and power of an unsprung vehicle mass, such as a chassis component or a body component (e.g., a wheel hub or a suspension control arm). The vertical acceleration frequency may be determined via applying a Fourier transform to an output signal of an accelerometer located on the unsprung vehicle component. The signal power and frequency are determined via the signal power and Fourier transform described at 604. Method 600 proceeds to 608.

[0061] At 608, method 600 estimates road roughness. In one example, method 600 estimates road roughness based on the output of a three-axis accelerometer. Specifically, average or integrated values ​​of vertical acceleration, longitudinal acceleration, and lateral acceleration over a predetermined time are summed to provide a single value that provides an indication of road roughness. Vertical, longitudinal, and lateral accelerations may be weighted to increase or decrease the influence of the respective axes via a weighting factor for each of the respective axes. Additionally, the estimate of road roughness is altered in response to the suspension mode in which the vehicle is operating. In one example, road roughness may be determined via the following formula:

[0062] RR=Sm((Pv·W 1 )+(Pl·W 2 )+(Pt·W 3 ))

[0063] Where RR is the road roughness, Sm is the multiplier for the suspension mode, Pv is the power output from the vertical accelerometer, Pl is the power output from the longitudinal accelerometer, Pt is the power output from the lateral accelerometer, and W 1 is the weighting factor for the vertical accelerometer, W 2 is the weighting factor for the longitudinal accelerometer, and W3 is a weighting factor for the lateral accelerometer. The value of Sm may be different for different suspension modes, such that changing the suspension mode may cause an increase in the actual total number of active cylinder modes by increasing the road roughness value. For example, a sport suspension mode may have a higher damping ratio than a cruise suspension mode. Therefore, the value of Sm may be adjusted such that the road roughness value increases in order to cause the vehicle to operate in the sport suspension mode. Therefore, depending on the road the vehicle is traveling on, changing the suspension mode of the vehicle may increase or decrease the actual total number of available cylinder modes. After estimating the road roughness, method 600 proceeds to 610.

[0064] At 610 , method 600 adjusts torque converter slip in response to road roughness, frequency of unsprung suspension components, and the actual total number of activated engine cylinders. Figure 4 In one example shown in , in response to the vehicle moving from traveling on a rough road to traveling on a smoother road, torque converter slip can be increased by at least partially opening the torque converter clutch such that driveline NVH can be less noticeable to vehicle occupants when the vehicle is traveling on the smoother road. Conversely, in response to the vehicle moving from traveling on a smoother road to traveling on a rougher road, torque converter slip can be reduced by at least partially closing the torque converter clutch such that vehicle fuel economy can be increased when driveline NVH can be less noticeable to vehicle occupants. In addition, torque converter slip can be adjusted in response to the frequencies of unsprung and sprung vehicle suspension components. For example, torque converter slip can be adjusted in response to the frequency of a sprung or unsprung vehicle suspension component being close to a harmonic of the engine firing frequency such that chassis vibrations can not exacerbate driveline NVH. Torque converter slip can also be adjusted in response to the actual total number of active engine cylinders, such as in Figure 4 For example, if the actual total number of active engine cylinders increases, torque converter slip may be reduced for a given engine speed and load. Method 600 proceeds to 612.

[0065] At 612, method 600 determines whether torque converter slip is greater than (GT) a first threshold for the current activated cylinder mode and the actual total number of activated engine cylinders or whether the vehicle suspension is being changed from a stiffer suspension mode to a more compliant suspension mode. In one example, the first threshold is based on or is a function of several parameters, including a desired level of driveline NVH that may be based on road surface conditions, a vehicle fuel economy benefit of operating the vehicle with fewer total activated engine cylinders, and a vehicle fuel economy disadvantage of increasing torque converter slip, such as with respect to Figure 4If method 600 judges that torque converter slip is greater than a first threshold for the currently activated cylinder mode and the actual total number of activated engine cylinders, the answer is yes and method 600 proceeds to 614. Otherwise, the answer is no and method 600 proceeds to 620.

[0066] At 614 , method 600 increases the actual total number of active engine cylinders and decreases the actual total number of active cylinder modes. Figure 4 Such operation is shown moving from operating point 410 to operating point 425 and from operating point 412 to operating point 430. By increasing the actual total number of active engine cylinders, driveline NVH can be effectively reduced while reducing driveline NVH in response to road conditions and vehicle occupant driveline NVH expectations. Method 600 proceeds to 616.

[0067] At 616, method 600 adjusts torque converter slip in response to road roughness, frequency of sprung and unsprung vehicle suspension components, and the actual total number of newly activated engine cylinders. Method 600 adjusts torque converter slip in response to newly activated cylinders as described at 610. Method 600 exits.

[0068] At 620, method 600 determines whether torque converter slip is less than (LT) a second threshold for the current activated cylinder mode and the actual total number of activated engine cylinders or whether the vehicle suspension is changed from a more compliant suspension mode to a stiffer suspension mode. In one example, the second threshold is based on or is a function of several parameters, including a desired level of driveline NVH that may be based on road surface conditions, a vehicle fuel economy benefit of operating the vehicle with fewer total activated engine cylinders, and a vehicle fuel economy disadvantage of increasing torque converter slip, such as with respect to Figure 4 Operating point 425 is an example of a second threshold associated with curve 404. If method 600 judges that torque converter slip is less than the second threshold for the currently activated cylinder mode and the actual total number of activated engine cylinders, the answer is yes and method 600 proceeds to 622. Otherwise, the answer is no and method 600 proceeds to 630.

[0069] At 622 , method 600 decreases the actual total number of active engine cylinders and increases the actual total number of active cylinder modes. Figure 4 Such operation is shown moving from operating point 425 to operating point 410 and from operating point 430 to operating point 412. By reducing the actual total number of active engine cylinders, driveline NVH can be increased under conditions where it can be less noticeable, such that vehicle fuel efficiency can be improved while meeting vehicle passenger driveline NVH expectations. Method 600 proceeds to 624.

[0070] At 624, method 600 adjusts torque converter slip in response to road roughness, frequency of sprung and unsprung vehicle suspension components, and the actual total number of newly deactivated engine cylinders (e.g., fewer active engine cylinders). Method 600 adjusts torque converter slip in response to newly deactivated cylinders as described at 610. Method 600 exits.

[0071] At 630, method 600 adjusts the total number of active cylinders and the total number of activated cylinder modes in response to the driver requested torque and engine speed. The driver requested torque can be determined based on the accelerator pedal position and the vehicle speed. For example, the accelerator pedal position and the vehicle speed can be input to a function or table that outputs an empirically determined driver requested torque. In one example, the actual total number of active cylinders and activated cylinder modes is determined based on a table having the driver requested torque and the engine speed as inputs. Method 600 proceeds to 632.

[0072] At 632, method 600 adjusts torque converter slip in response to driver demand torque and vehicle speed. In one example, method 600 queries or indexes a table or function that outputs desired torque converter slip in response to driver demand torque and vehicle speed. Torque converter slip is adjusted via applying and releasing the torque converter clutch. Method 600 exits.

[0073] In this way, the actual total number of activated engine cylinders and torque converter slip can be adjusted in response to road conditions, the fuel economy benefits of operating the engine with less than a full number of engine cylinders, and the fuel economy disadvantages of operating the driveline with a slipping torque converter.

[0074] therefore, Figure 6 The method provides an engine control method, comprising: increasing, via a controller, an actual total number of operating cylinders from a first actual total number of operating cylinders to a second actual total number of operating cylinders in response to torque converter slip exceeding a threshold value, the threshold value being a function of a fuel benefit and a fuel deficit. The method includes, wherein the fuel benefit is a reduction in engine fuel consumption provided by operating the engine with the first actual total number of operating cylinders. The method includes, wherein the fuel deficit is an increase in engine fuel consumption provided by operating the engine when the amount of torque converter slip is greater than a threshold value when the engine is providing a desired torque. The method includes, wherein the operating cylinders are burning air and fuel.

[0075] In some examples, the method further includes adjusting torque converter slip in response to increasing the actual total number of operating cylinders. The method includes where adjusting torque converter slip includes reducing torque converter slip. The method includes where reducing torque converter slip includes increasing an amount of closure of a torque converter clutch.

[0076] Figure 6 The method also provides an engine control method, comprising: increasing the actual total number of operating cylinders from a first actual total number of operating cylinders to a second actual total number of operating cylinders via a controller in response to torque converter slip exceeding a threshold value, the threshold value being a function of engine fuel economy and the actual total number of operating cylinders. The method further comprises adjusting the amount of torque converter slip and increasing the actual total number of available cylinder modes from the first actual total number of available cylinder modes to the second actual total number of available cylinder modes in response to changing from a first suspension control mode to a second suspension control mode. The method includes, wherein the first suspension mode includes a higher damping ratio than the second suspension mode. The method includes, wherein the threshold value further corresponds to an amount of vehicle vibration. The method includes, wherein the first actual total number of operating cylinders is less than the second actual total number of operating cylinders.

[0077] In some examples, the method further includes adjusting the slip of the torque converter in response to a frequency and an amplitude of a vertical acceleration of an unsprung suspension component. The method further includes reducing, via the controller, the actual total number of operating cylinders from the second actual total number of operating cylinders to the first actual total number of operating cylinders in response to the slip of the torque converter being less than the threshold.

[0078] Note that the example control and estimation programs included herein can be used with various engine and / or vehicle system configurations. The control methods and programs disclosed herein can be stored as executable instructions in a non-temporary memory and can be executed by a control system including a controller combined with various sensors, actuators and other engine hardware. The specific programs described herein can represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multi-tasking, multi-threading, etc. Therefore, the various actions, operations and / or functions described can be executed in the order shown, in parallel, or omitted in some cases. Similarly, the features and advantages of the example embodiments of the present invention described herein do not necessarily require the processing sequence, but the processing sequence is provided for ease of illustration and description. Depending on the specific strategy used, one or more of the illustrated actions, operations and / or functions can be repeatedly executed. In addition, at least a portion of the described actions, operations and / or functions can graphically represent the code of the non-temporary memory of the computer-readable storage medium programmed into the engine control system. When the described actions are executed by cooperating with one or more controllers to execute instructions in a system including various engine hardware components, the control action can also transform the operating state of one or more sensors or actuators in the physical world.

[0079] This specification ends here. Those skilled in the art will recognize many variations and modifications that do not depart from the spirit and scope of the invention by reading this specification. For example, I3, I4, I5, V6, V8, V10 and V12 engines operating on natural gas, gasoline, diesel or alternative fuel configurations may utilize this specification to benefit.

Claims

1. An engine control method, comprising: increasing, via the controller, the actual total number of operated cylinders from a first actual total number of operated cylinders to a second actual total number of operated cylinders in response to torque converter slip exceeding a threshold value that is a function of the fuel benefit and the fuel defect, wherein the torque converter slip is the difference between the torque converter impeller speed and the torque converter turbine speed, wherein the fuel benefit is a reduction in engine fuel consumption provided by operating the engine with the first actual total number of operating cylinders compared to operating the engine with the second actual total number of operating cylinders, and wherein the fuel defect is an increase in engine fuel consumption provided by operating the engine when the amount of torque converter slip is greater than the threshold when the engine is providing the desired torque.

2. The method of claim 1, wherein the operating cylinders are combusting air and fuel. 3 . The method of claim 1 , further comprising, in response to increasing the actual total number of operating cylinders, adjusting torque converter slip. 4 . The method of claim 3 , wherein adjusting torque converter slip includes reducing torque converter slip. 5 . The method of claim 4 , wherein reducing torque converter slip comprises increasing an amount of closure of the torque converter clutch.

6. A vehicle system comprising: an accelerometer coupled to the vehicle; an engine coupled to the vehicle; as well as A controller comprising executable instructions stored in a non-transitory memory to: determining, via the accelerometer, a frequency and a power of a vertical acceleration of a suspended mass of the vehicle; adjusting slip of a torque converter in response to a frequency of vertical acceleration of a mass of a suspension of a vehicle and a power of vertical acceleration of said mass of the suspension of said vehicle; increasing, via the controller, the actual total number of operated cylinders from a first actual total number of operated cylinders to a second actual total number of operated cylinders in response to torque converter slip exceeding a threshold value that is a function of the fuel benefit and the fuel defect, The torque converter slip is the difference between the torque converter impeller speed and the torque converter turbine speed. wherein the fuel benefit is a reduction in engine fuel consumption provided via operating the engine with the first actual total number of operating cylinders compared to operating the engine with the second actual total number of operating cylinders, and Wherein the fuel defect is an increase in engine fuel consumption provided by operating the engine when the amount of torque converter slip is greater than the threshold when the engine is providing the desired torque. 7 . The system of claim 6 , wherein adjusting slip of the torque converter includes at least partially releasing a torque converter clutch.

8. The system of claim 6, wherein adjusting slip of the torque converter includes at least partially closing a torque converter clutch.

9. The system of claim 8, wherein the accelerometer is coupled to an unsprung vehicle suspension component.

10. The system of claim 6, further comprising additional instructions to adjust an actual total number of operating cylinders in response to the frequency of vertical acceleration of the mass.

11. The system of claim 6, wherein adjusting slip of the torque converter in response to the frequency comprises: In response to the frequency increasing, slip of the torque converter is reduced.

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