Diagnostic Method for Variable Displacement Oil Pump of Engine

Abstract

This document discloses a method and system for diagnosing the operation of a variable displacement oil pump. In one example, the method may include commanding a displacement change of the variable displacement oil pump during a vehicle key-off state and diagnosing degradation of the oil pump based on a corresponding change in estimated crankcase pressure.

Description

Technical Field

[0001] The present description generally relates to methods and systems for diagnosing the operation of a variable displacement oil pump. Background Art

[0002] Internal combustion engines typically include a lubrication circuit, including an oil pump. The oil pump is mechanically connected to and driven from the engine crankshaft, so that its output flow rate is directly related to the crankshaft speed. Traditionally, oil pumps have been fixed-displacement pumps, often oversized to ensure adequate oil delivery at low speeds when the pump rotates slowly, and at high speeds when the pump rotates quickly. Therefore, fixed-displacement pumps discharge a fixed amount of oil per crankshaft rotation, thereby ensuring proper lubrication of moving engine components at both low and high engine speeds. However, within a given engine speed range, the oil delivery rate may exceed the engine's required oil capacity, resulting in inefficient use of engine power. For example, at high engine speeds, the high-speed oil pump may over-deliver oil due to the increased crankshaft speed. Excess oil is typically handled by a relief valve, which directs the excess oil to the engine oil sump. Ultimately, when the oil pump delivers more oil than the engine requires, pumping losses occur.

[0003] To minimize the penalty caused by pumping losses and reduce fuel consumption, the oil pump in recent internal combustion engines may be a variable displacement oil pump (VDOP). The VDOP configuration may include a vane-type pump, in which a solenoid-controlled valve can control the length of the vanes to adjust the oil displacement and, in some examples, the oil pressure, thereby reducing parasitic loads on the engine crankshaft during high engine speeds and ultimately saving fuel. This type of VDOP can alternate between a high-displacement mode and a low-displacement operating mode to deliver a desired amount of oil based on engine operating conditions such as engine speed and torque. For example, at high engine speeds, the solenoid-controlled valve can be energized to operate the VDOP in low-displacement mode, so that the VDOP does not deliver excessive oil, thereby minimizing pumping losses, reducing fuel consumption, and improving fuel economy. In contrast, at low engine speeds, the solenoid-controlled valve can be de-energized to return the VDOP to high-displacement mode, causing the VDOP to discharge a larger amount of oil to compensate for the slower oil pump speed, thereby delivering the appropriate amount of oil for engine protection. However, in some situations, the VDOP may not switch correctly between displacement modes and may become stuck in a given displacement or between displacements. For example, if the VDOP is stuck in a low displacement mode, insufficient oil may be delivered to the engine during low engine speed conditions, increasing engine wear and potentially causing engine degradation. For this reason, the vehicle may be configured to perform diagnostics to detect whether the variable displacement oil pump is discharging the appropriate amount of oil when commanded to a given displacement mode.

[0004] Murray et al., in U.S. Patent No. 8,734,122, disclose an exemplary method for diagnosing VDOP operation. Here, a variable flow oil pump state switch can be determined based on the oil pressure differential sensed by an oil pressure sensor. For example, the variable flow oil pump can switch from a low flow state to a high flow state during engine speed and load changes, and the subsequent oil pressure change can be measured by the oil pressure sensor. Based on a comparison of the expected pressure change with the observed pressure change, the diagnostic oil pressure sensor can indicate when the variable flow oil pump has not switched states, as indicated by engine demand.

[0005] However, the inventors herein have recognized potential issues with such systems. As one example, the engine oil pressure sensor used to diagnose the operation of the variable displacement oil pump may malfunction, leading to an erroneous diagnosis of a pump failure. Furthermore, if a malfunction in the oil pressure sensor is identified, an alternative method for diagnosing VDOP operation is needed. As another example, during a drive cycle, the vehicle may not be driven at high engine speed for as long as required to perform an oil pump diagnostic at low displacement. Consequently, the diagnostic routine may not detect if the pump is stuck in the low displacement setting. Summary of the Invention

[0006] In one example, the aforementioned issues may be addressed by an engine method that includes indicating degradation of a variable displacement oil pump (VDOP) based on a change in estimated crankcase pressure when commanding a change in VDOP displacement. In this manner, by monitoring changes in crankcase pressure using commanded changes in VDOP operation, reliable diagnosis of VDOP operation may be performed.

[0007] In one example, a diagnostic routine for VDOP can be opportunistically performed during a vehicle key-off state when the engine is not running and the engine temperature is substantially equal to ambient temperature. Switching the variable displacement oil pump between high and low displacement modes can result in an expected and measurable change in crankcase pressure. During VDOP operation in high displacement mode, a greater amount of oil may be displaced, resulting in greater oil evaporation, relative to VDOP operation in low displacement mode. Therefore, the expected crankcase pressure during high displacement operation is higher than the expected crankcase pressure during low displacement operation. The variable displacement oil pump can be commanded to switch oil displacement modes by actuating (e.g., energizing / de-energizing) a solenoid of the oil pump. The diagnostic routine includes rotating the engine without fuel when VDOP is first actuated to high displacement mode (e.g., via a motor) by holding the solenoid in a de-energized state, and determining the crankcase pressure corresponding to the high displacement mode setting via a crankcase pressure sensor. The measured crankcase pressure corresponding to the high displacement mode can be compared to a first baseline pressure. The VDOP can then be operated in low displacement mode by energizing the solenoid, and the crankcase pressure corresponding to the low displacement mode setting can be estimated via the crankcase pressure sensor. The crankcase pressure corresponding to the low displacement mode can be compared to a second baseline pressure. If it is determined that the crankcase pressure corresponding to the high displacement mode is substantially equal to the first baseline pressure and, upon energizing the solenoid, the crankcase pressure drops and the crankcase pressure corresponding to the low displacement mode is substantially equal to the second baseline pressure, it can be inferred that the VDOP is operating as intended. However, if it is determined that the crankcase pressure corresponding to the high displacement mode is lower than the first baseline pressure, it can be inferred that the VDOP is stuck in low displacement mode. If the pump is diagnosed as being stuck in low displacement mode, the idle engine speed can be increased to mitigate engine wear. If it is determined that the crankcase pressure does not drop after the pump displacement is switched, it can be inferred that the VDOP is stuck in high displacement mode.

[0008] In this way, by appropriately utilizing existing engine components (such as a crankcase pressure sensor), the need for additional sensors and / or equipment for VDOP diagnosis can be reduced. The technical benefit of performing VDOP diagnosis during the vehicle's key-off state is that both displacement modes can be diagnosed without waiting for engine speed changes during on-road vehicle operation. By identifying the stuck VDOP position, appropriate mitigation measures can be taken. In summary, by regularly monitoring the health of the VDOP, engine wear can be reduced, lubricant usage can be reduced, and fuel efficiency can be improved.

[0009] It should be understood that the above summary is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is uniquely defined by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 An exemplary vehicle system with a variable displacement oil pump (VDOP) is schematically illustrated.

[0011] Figure 2 A flow chart illustrating an exemplary control procedure for operating a VDOP according to an embodiment of the present disclosure is shown.

[0012] Figure 3 A flow chart illustrating a diagnostic routine for diagnosing a VDOP stuck in oil displacement mode is shown.

[0013] Figure 4 An exemplary diagnostic of a variable displacement oil pump based on crankcase pressure according to the present disclosure is shown. DETAILED DESCRIPTION

[0014] The following description relates to diagnostic Figure 1 The system and method for a variable displacement oil pump (VDOP) in an exemplary engine shown in FIG. The VDOP may be used to adjust the oil pressure according to the Figure 2 The routine shown in provides oil flow to the engine in a manner that optimizes efficient engine operation, thereby improving vehicle fuel economy. The vehicle's engine controller can be configured to execute the exemplary routine to indicate degradation of the variable displacement oil pump. In one example, the Figure 3 To diagnose the oil pump, VDOP can be commanded to switch the oil displacement mode via actuation of a solenoid, and the resulting change in crankcase pressure can indicate pump status. Figure 4Example engine operation is shown implementing VDOP diagnostics during a vehicle key-off state.

[0015] Figure 1 Schematic diagram 100 of a vehicle system 102 is shown. In some examples, vehicle system 102 may be a hybrid electric vehicle system. Vehicle system 102 includes an exemplary system configuration of a multi-cylinder internal combustion engine, generally depicted at 10. Engine 10 may be controlled at least partially by a control system including controller 12 and by input from a vehicle operator 130 via an input device 132. In this example, input device 132 includes an accelerator pedal and a pedal position sensor 134 for generating a proportional pedal position signal PP.

[0016] Engine 10 may include a lower portion of an engine block, generally designated 26, which may include a crankcase 28 surrounding a crankshaft 30, with an oil sump 32 located below the crankshaft. An oil fill port 29 may be provided in crankcase 28 so that oil can be supplied to oil sump 32. Oil fill port 29 may include an oil cap 33 to seal oil fill port 29 when the engine is operating. A dipstick tube 37 may also be provided in crankcase 28 and may include a dipstick 35 for measuring the oil level in oil sump 32.

[0017] A variable displacement oil pump (VDOP) 180 may be positioned in oil sump 32 to supply lubricating oil to various engine components. VDOP 180 may be coupled to crankshaft 30, which provides rotational power to operate VDOP 180. In one example, variable flow oil pump 180 includes multiple internal rotors and associated eccentrically mounted vanes (not shown). At least one of the internal rotors may be coupled to a spring configured to be actuated by a solenoid 190, which is controlled by controller 12. When displaced by the solenoid, the spring may pivot the internal rotor relative to one or more of the other rotors, resulting in a variable vane length, thereby adjusting the output flow rate and oil pressure from VDOP 180. VDOP 180 may selectively provide oil to engine oil galleries 192, which provide oil to various areas and / or components of engine 10 for cooling and lubrication. The output flow rate, or oil pressure, of variable flow oil pump 180 may be adjusted by controller 12 to accommodate changing operating conditions in order to provide varying levels of cooling and / or lubrication. In one example, the oil pressure may be estimated via pressure sensor 188 located downstream of the output of VDOP 180. Furthermore, the oil pressure output from VDOP 180 may be adjusted to reduce oil consumption and / or reduce energy consumption of VDOP 180.

[0018] It should be appreciated that a suitable variable flow oil pump configuration may be implemented to vary the oil pressure and / or oil flow rate. In some embodiments, instead of being coupled to the crankshaft 30, the VDOP 180 may be powered by a different power source, such as a motor. The VDOP 180 may include Figure 1 Additional components not described in (such as a hydraulic regulator).

[0019] Additionally, crankcase 28 may include a plurality of other ports for servicing components in crankcase 28. These ports in crankcase 28 may remain closed during engine operation so that a crankcase ventilation system (described below) may operate during engine operation.

[0020] An upper portion of engine block 26 may include a combustion chamber (i.e., cylinder) 34. Combustion chamber 34 may include combustion chamber walls 36 with piston 38 positioned therein. Piston 38 may be coupled to crankshaft 30 so that reciprocating motion of the piston is translated into rotational motion of the crankshaft. Combustion chamber 34 may receive fuel from fuel injectors 45 (configured herein as direct fuel injectors) and intake air from intake manifold 42 located downstream of throttle 44. Engine block 26 may also include an engine coolant temperature (ECT) sensor 46 (described in greater detail below) that is input to engine controller 12.

[0021] Throttle 44 may be positioned in the engine air intake to control air flow into intake manifold 42, and upstream of the throttle may be compressor 50, followed by, for example, charge air cooler 53. Air filter 54 may be positioned upstream of compressor 50 and may filter fresh air entering intake passage 13. Intake air temperature (IAT) sensor 49 may be coupled to intake passage 13 upstream of air filter 54 to estimate ambient air temperature. Intake air may enter combustion chamber 34 via cam-actuated intake valve system 40. Similarly, exhaust gas after combustion may exit combustion chamber 34 via cam-actuated exhaust valve system 41. In alternative embodiments, one or more of the intake and exhaust valve systems may be electrically actuated.

[0022] Exhaust combustion gases exit combustion chamber 34 via exhaust passage 60 located upstream of turbine 62. An exhaust gas sensor 64 may be positioned along exhaust passage 60 upstream of turbine 62. Turbine 62 may be equipped with a wastegate (not shown) that bypasses it. Sensor 64 may be a suitable sensor for providing an indication of exhaust air-fuel ratio, such as a linear oxygen sensor or UEGO (universal or wide-range exhaust gas oxygen sensor), a two-state oxygen sensor or EGO, HEGO (heated EGO), nitrogen oxides (NOx), hydrocarbons (HC), or carbon monoxide (CO) sensor. Exhaust gas sensor 64 may be coupled to controller 12.

[0023] exist Figure 1 In some examples, a positive crankcase ventilation (PCV) system 16 is coupled to the engine intake so that gases in the crankcase can be vented from the crankcase in a controlled manner. During non-boosted conditions (when manifold pressure (MAP) is less than barometric pressure (BP)), the crankcase ventilation system 16 draws air into the crankcase 28 via a breather valve or crankcase ventilation tube 74. A first side 101 of the crankcase ventilation tube 74 can be mechanically coupled or connected to the fresh air intake 13 upstream of the compressor 50. In some examples, the first side 101 of the crankcase ventilation tube 74 can be coupled to the intake 13 downstream of the air filter 54 (as shown). In other examples, the crankcase ventilation tube can be coupled to the intake 13 upstream of the air filter 54. A second, opposing side 103 of the crankcase ventilation tube 74 can be mechanically coupled or connected to the crankcase 28 via the oil separator 81.

[0024] The crankcase ventilation tube 74 also includes a crankcase pressure sensor 77 coupled therein for providing an estimate of the air flowing through the crankcase ventilation tube 74 (e.g., pressure, flow rate, etc.). The pressure sensor 77 can be an absolute pressure sensor or an instrument sensor. In an alternative embodiment, the sensor 77 can be a flow sensor or a flow meter. In another embodiment, the sensor 77 can be configured as a venturi tube. One or more additional pressure and / or flow sensors can be coupled to the crankcase ventilation system at alternate locations. For example, a barometric pressure sensor (BP sensor) 47 can be coupled to the intake passage 13 upstream of the air filter 54 to provide an estimate of atmospheric pressure. In addition, a pressure sensor 59 can be coupled downstream of the compressor 50 to provide an estimate of the throttle inlet pressure (TIP).

[0025] PCV system 16 also vents gases from the crankcase via conduit 76 (also referred to herein as PCV line 76) and into intake manifold 42. In some examples, PCV line 76 may include a one-way PCV valve 78 (i.e., a passive valve that tends to seal when flow is in the opposite direction) to continuously vent crankcase gases from inside crankcase 28 before connecting to intake manifold 42.

[0026] Crankcase pressure sensor 77 can be used to diagnose VDOP 180 when appropriate. During a key-off state, the high-displacement mode of VDOP can be the default mode. A change in VDOP displacement can be commanded during an unfueled engine cranking operation at engine idle speed, performed via the electric motor during a key-off state, when the engine temperature is substantially equal to the ambient temperature. VDOP displacement operation can transition from a high-displacement mode with the solenoid de-energized to a low-displacement mode with the solenoid energized. During VDOP operation in the high-displacement mode, a first crankcase pressure can be estimated via pressure sensor 77, and in response to the first crankcase pressure being below a first baseline pressure, an indication that VDOP 180 is stuck in the low-displacement mode can be provided. During VDOP operation in the low-displacement mode, a second crankcase pressure can be estimated via pressure sensor 77, and in response to the second crankcase pressure being above a second baseline pressure, an indication that VDOP 180 is stuck in the high-displacement mode can be provided. In one example, when the VDOP 180 is installed, a first baseline pressure may be established via the crankcase pressure sensor 77 by operating the VDOP 180 in a first displacement mode while cranking the engine at idle speed without fuel, and when the VDOP 180 is installed, a second baseline pressure may be established via the crankcase pressure sensor 77 by operating the VDOP 180 in a second displacement mode while cranking the engine at idle speed without fuel. Figure 3 Describes the details of the VDOP diagnostic procedure.

[0027] The controller 12 Figure 1 Controller 12 is shown as a microcomputer and includes a microprocessor unit 108, input / output ports 110, an electronic storage medium for executable programs and calibration values ​​(shown as a read-only memory chip 112 in this particular example), random access memory 114, keep-alive memory 116, and a data bus. Controller 12 can receive various signals from sensors coupled to engine 10, including intake mass air flow (MAF) measurements from mass air flow sensor 58, engine coolant temperature (ECT) from temperature sensor 46, ambient temperature from intake air temperature sensor 49, PCV pressure from vacuum sensor 82, exhaust gas air-fuel ratio from exhaust gas sensor 64, oil pressure sensor 188, crankcase vent tube pressure sensor 77, BP sensor 57, TIP sensor 59, and the like. Furthermore, controller 12 can monitor and adjust the positions of various actuators based on input received from the various sensors. These actuators may include, for example, throttle 44, intake and exhaust valve systems 40 and 41, solenoid 190, and PCV valve 78. Storage medium read-only memory 112 can be programmed with computer readable data representing instructions executable by processor 108 for performing the methods described below as well as other variants that are anticipated but not specifically listed.

[0028] Controller 12 can adjust the operation of variable-displacement oil pump 180 in response to various operating conditions, such as engine speed. Controller 12 can operate variable-displacement oil pump 180 by energizing solenoid 190. In one example, controller 12 can energize solenoid 190 at high engine speeds. When energized, solenoid 190 can displace a spring actuator (not shown), which can pivot the internal rotor of the variable-displacement oil pump, causing the vane length to change, thereby adjusting the pump to deliver a lower amount of oil to the engine. Conversely, at low engine speeds, controller 12 can de-energize the solenoid to return it to its default position, allowing the oil pump to deliver a higher amount of oil to the engine. In other examples, controller 12 can adjust the operation of variable-displacement oil pump 180 in response to the engine being in a boosted versus naturally aspirated state (e.g., when compressed air is being transferred to the engine, variable-displacement oil pump 180 can be controlled to increase output). Controller 12 may also receive an indication of oil pressure from pressure sensor 188 located downstream of the output of variable flow oil pump 180. Controller 12 may use the indication of oil pressure to control adjustments to the oil pressure by varying the oil flow rate output from the oil pump. Upon indicating degradation of oil pump 180, during immediately subsequent engine operation, controller 12 may adjust the engine idle speed, such as by increasing the engine idle speed, when indicating that VDOP 180 is stuck in low displacement mode.

[0029] In this way, Figure 1 A system for an engine is implemented by components, the system including: an electric motor connected to a battery and capable of rotating the engine; a crankcase including a variable displacement oil pump mechanically connected to the engine; a solenoid configured to adjust the displacement of the oil pump; a crankcase ventilation tube mechanically connected to the intake passage upstream of the compressor, the tube also mechanically connected to the crankcase; a crankcase pressure sensor connected to the crankcase ventilation tube; and a controller having computer-readable instructions stored on a non-transitory memory for performing the following items: commanding a displacement change of the variable displacement oil pump via the solenoid during engine cranking without fuel via the electric motor, sensing crankcase pressure via the crankcase pressure sensor before and after the commanded change in displacement, and indicating degradation of the oil pump based on the sensed crankshaft pressure relative to a baseline pressure.

[0030] Figure 2 A variable displacement oil pump (such as Figure 1 The exemplary method 200 for VDOP 180 in FIG. 200 may be performed by a controller based on instructions stored in a memory of the controller and in conjunction with sensors from the engine system (such as those referenced above). Figure 1The controller may use the signals received from the sensors described herein to execute instructions for performing method 200 and the remaining methods included herein. According to the method described below, the controller may use the engine actuators of the engine system (such as Figure 1 solenoid 190 in the motor to adjust engine operation.

[0031] At 202 , method 200 includes determining engine and vehicle operating conditions. Operating conditions may include engine speed, engine load, vehicle speed, pedal position, throttle position, mass air flow, air-fuel ratio, engine temperature, compressed air volume in the intake from the turbocharger, engine oil temperature, etc.

[0032] At 204, the method includes determining whether the engine speed is greater than a threshold. In one example, a controller of the vehicle may determine the engine speed and may compare it to a non-zero speed threshold stored as a predetermined threshold to determine whether the engine is operating at a speed greater than the threshold. In one example, the engine speed threshold may be 1800 RPM, such that the oil pump may be switched to low-displacement mode at engine speeds typically exhibited during highway cruising. In other examples, the engine speed threshold may be 2500 RPM or higher, such that the oil pump may be switched to low-displacement mode only during periods of high engine speed travel, such as during an operator tip-in.

[0033] If the engine speed is determined to be below a threshold speed, at 206 , the oil pump may be maintained in a high-displacement mode with the solenoid de-energized. As previously described, the variable displacement oil pump (VDOP) can alternate between a high-displacement mode and a low-displacement mode based on engine operating conditions (such as engine speed). For a given engine speed value, a variable displacement oil pump in high-displacement mode can circulate a mass flow of lubricating oil that is greater than the mass flow of lubricating oil circulated by the same VDOP in low-displacement mode. The variable oil displacement of the oil pump may be controlled by a spring actuator operably coupled to a solenoid, which can facilitate changes in displacement mode to deliver variable oil volumes through the oil pump. In one example, at low engine speeds (such as engine speeds below a speed threshold), the solenoid controlling oil displacement from the VDOP may be in a default de-energized position, and the VDOP may be operated at a higher displacement setting, allowing an appropriate (larger) amount of oil to be delivered to the engine for protection / lubrication of engine components. The default mode of the oil pump may be high displacement mode (so when the solenoid is de-energized, the pump may be in high displacement mode) to avoid engine wear if the solenoid degrades. However, other configurations are possible, such as the solenoid being energized to adjust the oil pump to high displacement mode.

[0034] If it is determined that the engine is running at a speed above a threshold, then at 208, the oil pump solenoid may be energized. The solenoid energization may be directed by a controller, wherein the solenoid may be operably connected to a spring actuator that is responsible for changing the blade length and thereby changing the pump displacement. At 210, method 200 may switch the oil pump to a low displacement mode via solenoid energization. When energized, the solenoid may adjust the oil pump to a lower displacement to discharge a smaller amount of oil relative to the high displacement mode, thereby minimizing pumping losses. Therefore, the engine's fuel consumption may be reduced and fuel economy may be improved. In this way, switching from operating in a high displacement mode to operating in a low displacement mode includes energizing the solenoid.

[0035] At 212 , during a subsequent vehicle key-off state, the controller may initiate a VDOP diagnostic as appropriate. Figure 3 Discusses the details of the VDOP diagnostic procedure.

[0036] In this way, based on engine operating conditions (such as engine speed), the variable displacement oil pump can cycle between a high oil displacement configuration and a low oil displacement configuration, such as Figure 2 Specifically, the VDOP can operate in a high displacement mode at low engine speeds and switch to a low displacement mode at high engine speeds to meet engine lubrication and fuel economy requirements without sustaining pumping losses.

[0037] Now turn Figure 3 , a flow chart illustrating an exemplary diagnostic method 300 for diagnosing a variable displacement oil pump stuck in oil flow displacement mode is shown. Method 300 may be part of method 200 and may be performed at step 212 .

[0038] At 302, the routine includes determining whether the vehicle is in a key-off state. The key-off state includes a state when the vehicle is not using engine torque and / or machine torque for propulsion. During the key-off state, the vehicle may be parked in a stationary position. If it is determined that the vehicle is not in the key-off state, it can be inferred that the vehicle is running, and at 304, the current vehicle operation may be maintained without initiating a VDOP diagnostic. The VDOP operating mode may continue to be adjusted based on engine speed.

[0039] If it is determined that the vehicle is in a key-off state, at 306 , the routine includes determining whether input conditions are met for initiating a VDOP diagnostic. In one example, the input conditions for initiating a VDOP diagnostic include the engine temperature, estimated via the engine coolant temperature sensor, being substantially equal to the ambient temperature, estimated via the intake air temperature sensor. As an example, substantially equal includes the engine temperature being within a threshold margin of the ambient temperature. In one example, the threshold margin may be 5%. During engine operation, crankcase pressure may be affected by ambient heating (such as from engine combustion, crankcase rotation, transmission exhaust heat, driveshaft heat, friction brake heat, fuel system pump operation, asphalt heating, etc.). In another example, a VDOP diagnostic may be performed after a predetermined duration following a key-off event, or in the case of an unoccupied autonomous vehicle, in response to a controller wakeup. Furthermore, before initiating a VDOP diagnostic, the controller may verify whether a predetermined duration has elapsed since a previous VDOP diagnostic routine. In some examples, such a predetermined duration may include 1 day, greater than 1 day but less than 2 days, greater than 2 days, etc.

[0040] In certain conditions, a VDOP diagnostic can be performed even while the vehicle is in motion. In one example, fuel economy may be affected during a VDOP diagnostic, so the controller can opportunistically perform the diagnostic during a deceleration fuel shutoff (DFSO) state, such as when the vehicle is coasting downhill and not consuming fuel. In another example, if motor torque is used to propel the vehicle, the electric motor can be used to crank the engine without fuel to perform the VDOP diagnostic. The battery charge used to perform the diagnostic can be recovered later in the drive cycle by regenerative braking to recharge the electric motor battery.

[0041] If it is determined that the input conditions for performing a VDOP diagnostic are not met, the VDOP diagnostic routine may be postponed until the diagnostic input conditions are met at 308. If it is determined that the input conditions for performing a VDOP diagnostic are met, it may be inferred that the estimated crankcase pressure may be proportional to the pumping action of the VDOP because the engine temperature has cooled to ambient temperature.

[0042] At 310, a first baseline pressure may be established for high displacement VDOP operation, and a second baseline pressure may be established for low displacement VDOP operation. In one example, establishing each of the first baseline pressure and the second baseline pressure includes the controller retrieving the first baseline pressure and the second baseline pressure from an onboard database. In one example, the VDOP may be installed by cranking the engine without fuel via a crankcase pressure sensor such as Figure 1 The pressure sensor 77 in the solenoid valve estimates the first baseline pressure and the second baseline pressure. Figure 1 The first baseline pressure may be estimated when the VDOP is operated in a high displacement mode (with the solenoid 190 in the engine deenergized). The second baseline pressure may be estimated when the VDOP is operated in a low displacement mode (with the solenoid 190 in the engine deenergized). In one example, installation of the VDOP may include assembling the VDOP to the engine at a manufacturing facility. In another example, installation of the VDOP may include replacing an old VDOP with a new VDOP at a repair location.

[0043] There may be a correlation between the first baseline pressure and the second baseline pressure. As an example, the second baseline pressure may be a function of the first baseline pressure. The first baseline pressure may be estimated (as described above), and then the second baseline pressure may be calculated based on the first baseline pressure. In one example, the second baseline pressure may be 30% of the first baseline pressure.

[0044] The first and second baseline pressures may be estimated over a first threshold duration since the VDOP was installed, and a VDOP diagnosis may be performed when the VDOP has been used for more than a second threshold duration, the second threshold duration being longer than the first threshold duration. In one example, the first threshold duration may be one day since the VDOP was installed. In another example, the second threshold duration may be 30 days since the VDOP was installed. Alternatively, the first and second baseline pressures may be estimated over a first threshold driving distance (of the vehicle) since the VDOP was installed, and a VDOP diagnosis may be performed when the VDOP has been used for more than a second threshold driving distance, the second threshold driving distance being longer than the first threshold driving distance. In one example, the first threshold distance may be 30 miles since the VDOP was installed. In another example, the second threshold distance may be 300 miles since the VDOP was installed. The first and second baseline pressures may be obtained while the engine is operating at an idle speed. In one example, the idle speed is 500 RPM.

[0045] At 312, using a motor such as Figure 1 The motor torque of the electric motor 52 in the pump rotates the engine without fuel. The controller can send a signal to the actuator of the electric motor to begin rotating the engine at an idle speed (such as 500 RPM or about 500 RPM). The controller can send a signal to the spring actuator on the solenoid operably coupled to the VDOP to operate the VDOP in high displacement mode. In high displacement mode, the solenoid remains in the default de-energized position. When the pump is operated in high displacement mode, the pumping work done by the VDOP can be higher and the oil passages (such as Figure 1The engine oil passage 192 in the VDOP is used to supply more oil (lubricant). As the VDOP is operated to discharge more oil, more oil may evaporate, thereby increasing the crankcase pressure.

[0046] At 314, a first crankcase pressure during VDOP operation in high displacement mode may be estimated via the crankcase pressure sensor. At 316, the routine includes determining whether the crankcase pressure is below a first baseline pressure. In one example, the controller may determine whether the crankcase pressure is greater than a threshold value (e.g., greater than 10%) below the first baseline pressure. As previously described, the first baseline pressure corresponds to the crankcase pressure estimated by the crankcase pressure sensor during VDOP operation in high displacement mode when the VDOP is installed.

[0047] If it is determined that the first crankcase pressure is lower than the first baseline pressure, it can be inferred that even though the VDOP is commanded to operate in the high displacement mode, the VDOP is stuck in the low displacement mode and is not discharging as much oil as the VDOP would have displaced when installed (during operation in the high displacement mode). Therefore, at 318, a diagnostic code (flag) indicating that the VDOP is stuck in the low displacement mode is set. For example, the operator can be notified by illuminating an indicator on the vehicle dashboard, alerting the vehicle driver to the notification.

[0048] Because the VDOP is stuck in the low displacement mode, during subsequent engine operation at a lower engine speed, it is impossible to supply enough oil to the engine components, thereby increasing the possibility of engine wear. Therefore, at 320, the controller can increase the engine idle speed to increase the oil supply to the engine components under the lower engine speed operation. The engine idle speed can include the speed of the engine when it is running during the idle speed engine state. For example, during the engine idle speed state (for example, when the engine is running but the vehicle is not propelled by the engine because the engine is disengaged from the vehicle driveline), the idle engine throttle can be controlled to a given position to keep the engine speed at the commanded idle speed. When the oil pump is not degraded, in a non-limiting example, the commanded idle speed can be 500RPM. If it is determined that the oil pump is stuck in the low displacement mode, then in a non-limiting example, the commanded idle speed can be increased to 1000RPM. Increasing the commanded idle speed may result in the idle engine throttle being controlled to a more open position and / or increasing the commanded idle speed may result in the intake throttle being controlled to a more open position during idling.

[0049] If it is determined at 316 that the crankcase pressure is not below the first baseline pressure, it can be inferred that the VDOP is operating in the commanded high-displacement mode and that the crankcase pressure is substantially equal to the first baseline pressure (e.g., within a 5% threshold of the first baseline pressure). At 322, the controller can signal a spring actuator operably coupled to the VDOP solenoid to operate the VDOP in a low-displacement mode with the solenoid energized. When the pump is operating in the low-displacement mode and the engine speed remains constant, a reduced amount of oil is supplied to the engine oil gallery. Because the VDOP displaces a reduced amount of oil, less oil may evaporate, thereby reducing the crankcase pressure.

[0050] At 323, a second crankcase pressure during VDOP operation in the low displacement mode may be estimated via a crankcase pressure sensor. At 324, the routine includes determining whether a drop in crankcase pressure is observed. In one example, the routine may determine whether the difference between the second crankcase pressure and the first crankcase pressure is greater than a non-zero threshold pressure differential. As an example, the threshold pressure differential may be calibrated based on the crankcase pressure estimated during VDOP operation in each of the high and low displacement modes when the VDOP is installed.

[0051] In another example, the routine may also determine whether the second crankcase pressure has decreased to a second baseline pressure (e.g., within 10% of the second baseline pressure) when transitioning from high-displacement mode to low-displacement mode. As previously described, the second baseline pressure corresponds to the crankcase pressure estimated by the crankcase pressure sensor during VDOP operation in low-displacement mode when VDOP is installed. In this way, when the engine is rotated without fuel via the electric motor during a key-off state of the vehicle, each of the first crankcase pressure, the second crankcase pressure, the first baseline pressure, and the second baseline pressure may be estimated via the crankcase pressure sensor.

[0052] If it is determined that when the solenoid is energized and the VDOP is operating in low displacement mode, the difference between the second crankcase pressure and the first crankcase pressure is above a threshold pressure difference and / or the crankcase pressure has dropped to a second baseline pressure, then at 326 the controller may indicate that the pump has not degraded. However, if it is determined that the difference between the second crankcase pressure and the first crankcase pressure is below a threshold pressure difference or the second crankcase pressure is above the second baseline pressure, then it may be inferred that the VDOP is stuck in high displacement mode even though the VDOP is commanded to operate in low displacement mode. Therefore, at 328, a diagnostic code (flag) is set indicating that the VDOP is stuck in high displacement mode. For example, the operator may be notified by illuminating an indicator on the vehicle dashboard to alert the vehicle driver of the receipt of the notification. Because the VDOP is stuck in high displacement mode, during engine operation above a threshold speed (such as Figure 2(as discussed in step 204 of FIG), more oil volume may be pumped, thereby increasing pumping losses. Furthermore, fuel economy may be adversely affected due to VDOP operation in the high displacement mode at each engine speed.

[0053] At 330 , the diagnostic routine is complete and the engine may no longer be rotated. The controller may send a signal to the motor powering the engine to stop rotating the engine, and the engine may return to a stopped state.

[0054] In this way, during a key-off state, for a variable displacement oil pump that can switch from operating in a high-displacement mode to operating in a low-displacement mode via a solenoid, a first crankcase pressure can be estimated while the pump is operating in the high-displacement mode, the pump can be indicated as being stuck in the low-displacement mode based on the first crankcase pressure being lower than a first baseline pressure, and during a subsequent key-on state, the engine idle speed can be increased in response to the oil pump being stuck in the low-displacement mode.

[0055] Figure 4 An exemplary timeline 400 is shown illustrating diagnostics of a variable displacement oil pump (VDOP). The horizontal (x-axis) represents time, while vertical markers t1 through t5 represent significant times in the VDOP diagnostic routine.

[0056] The first graph (line 402) shows the change in vehicle speed over time. The second graph (line 404) shows the engine temperature estimated via the engine coolant temperature sensor. The dotted line 406 shows the ambient temperature estimated via the intake air temperature sensor. The third graph (line 408) shows the operation of the solenoid controlled valve coupled to the VDOP. The solenoid can be energized to switch the operation of the VDOP from a high displacement mode to a low displacement mode. The fourth graph (line 410) shows the change in engine speed over time. The dotted line 409 shows the threshold engine speed above which the VDOP can operate in the low displacement mode. The threshold speed 409 can be a non-zero speed threshold calibrated based on the engine oil displacement corresponding to the engine operation at each engine speed. The fifth graph (line 412) shows the crankcase pressure sensor (such as Figure 14. The crankcase pressure is estimated by the crankcase pressure sensor 77 in FIG. 4. The dotted line 413 shows a first baseline pressure estimated by the crankcase pressure sensor when the VDOP is installed by cranking the engine without fuel when the VDOP is operating in a high displacement mode. The dotted line 415 shows a second baseline pressure estimated by the crankcase pressure sensor when the VDOP is installed by cranking the engine without fuel when the VDOP is operating in a low displacement mode. The sixth graph (line 418) shows the operating mode of the VDOP. The seventh graph (line 419) shows the operation of the motor connected to a hybrid electric vehicle (HEV). The machine can be operated to provide motor torque to propel the HEV. The seventh graph (line 420) shows the position of a mark indicating degradation of the VDOP.

[0057] Prior to time t1, engine torque is used to propel the vehicle and the HEV motor is not operating. Based on engine speed exceeding threshold 409, VDOP operates in high displacement mode with the solenoid de-energized. During this time, crankcase pressure is a function of engine operating conditions, such as engine temperature and VDOP operation in high displacement mode. Because VDOP diagnostics have not yet been performed, the flag remains off.

[0058] At time t1, the engine is shut down and the vehicle is stopped. When the engine is not running, lubrication of engine components is not required, so VDOP operation is stopped at time t1. Between times t1 and t2, no engine torque and / or machine torque is used to propel the vehicle. While combustion is paused, no engine heat is generated, and engine temperature may steadily decrease as existing engine heat dissipates into the atmosphere.

[0059] At time t2, when the engine temperature drops to ambient temperature, it can be inferred that the crankcase pressure is no longer affected by the increase in engine temperature (relative to ambient temperature). Therefore, at time t2, diagnosis of the VDOP is initiated. The controller sends a signal to the motor to rotate the engine at engine idle speed without fuel. Between times t2 and t3, the solenoid coupled to the VDOP remains in the de-energized state while the VDOP operates in high displacement mode. Since the VDOP operates in high displacement mode, fuel vapor formed in the crankcase causes the crankcase pressure to increase. The increase in crankcase pressure to the first baseline pressure 413 (as estimated during VDOP operation in high displacement mode when the VDOP is installed) indicates that the VDOP has not degraded and is operating in the commanded high displacement mode. Because it is inferred that the VDOP is not stuck in low displacement mode, the flag remains in the off state.

[0060] However, if between t2 and t3, it is observed that the crankcase pressure (as shown by dashed line 417) remains substantially equal to the second baseline pressure 415 even though the VDOP is commanded to operate in the high displacement mode, it can be inferred that the VDOP has degraded and is stuck in the low displacement mode. After time t2, a flag 420 indicating that the VDOP is stuck in the low displacement mode will be set.

[0061] At time t3, the solenoid is actuated to the energized position, and VDOP operation transitions from high displacement mode to low displacement mode. Since VDOP is operating in low displacement mode, between times t3 and t4, the work performed by VDOP is lower relative to pump operation in high displacement mode, thereby generating lower amounts of fuel vapor. The decrease in crankcase pressure to the second baseline pressure 415 (as estimated during VDOP operation in low displacement mode when VDOP is installed) indicates that VDOP has not degraded and can transition from high displacement mode to low displacement mode. Because it is inferred that VDOP is not stuck in high displacement mode, the flag remains closed.

[0062] However, if between t3 and t4, it is observed that the crankcase pressure (as shown by dashed line 416) does not decrease from the crankcase pressure corresponding to high displacement VDOP operation even though the VDOP is commanded to operate in the low displacement mode, it can be inferred that the VDOP is degraded and stuck in the high displacement mode. After time t3, a flag 422 will be set indicating that the solenoid is not energized and the VDOP is stuck in the high displacement mode.

[0063] At time t4, upon completion of the VDOP diagnostics, the controller sends a signal to the HEV electric motor to suspend operation of the motor and stop cranking the engine. Between times t4 and t5, the vehicle is not propelled and the engine remains in a non-combustion state.

[0064] At time t5, the vehicle starts from a standstill and uses engine torque for propulsion. The engine is cranked until the engine speed increases to the idle speed. Due to the engine speed being below the threshold, the solenoid can remain in the de-energized state and the VDOP can operate in a high displacement mode to supply a desired amount of lubricant to the engine components. When it is determined during the VDOP diagnosis that the VDOP has not degraded, upon engine restart, the engine idle speed is maintained (maintained at the level before the diagnostic process). However, if it is determined that the VDOP is still stuck in the low displacement mode even during engine operation below the threshold engine speed, as shown by dotted line 411, the idle speed will be increased to the threshold engine speed. When the idle speed is increased, even if the VDOP is stuck in the low displacement mode, since the crankshaft rotates at a higher speed, an increased amount of lubricant will still be discharged, thereby reducing the possibility of engine wear due to increased friction (lack of lubrication).

[0065] In this way, by performing diagnosis of the VDOP during the vehicle key-off state, the VDOP can be operated in both displacement modes without having to wait for a change in the engine speed to identify the displacement mode in which the VDOP is stuck. By identifying the displacement mode in which the VDOP is stuck, appropriate changes to the engine idle speed can be performed during subsequent engine operation, and engine wear due to insufficient lubrication can be reduced. The technical effect of using existing engine components (such as a crankcase pressure sensor) for VDOP diagnosis is that the need for additional sensors and / or equipment for diagnosing VDOP can be reduced. By monitoring the VDOP, displacement changes occur in response to the commanded operation of the solenoid, ensuring optimal use of lubricant without waste. In summary, by regularly monitoring the health of the VDOP, engine operation and fuel efficiency can be improved.

[0066] An exemplary method includes indicating degradation of a variable displacement oil pump (VDOP) based on a change in estimated crankcase pressure when a commanded change in VDOP displacement occurs. In any of the foregoing examples, the method further includes, additionally or alternatively, adjusting engine idle speed during an immediately subsequent period of engine operation in response to the indication of VDOP degradation. In any or all of the foregoing examples, the method further includes, additionally or alternatively, commanding a change in VDOP displacement during a vehicle key-off state when engine temperature is substantially equal to ambient temperature. In any or all of the foregoing examples, additionally or alternatively, commanding the change in VDOP displacement includes commanding the change while cranking the engine without fuel via an electric motor during the vehicle key-off state. In any or all of the foregoing examples, additionally or alternatively, the commanded change in VDOP displacement is from a high displacement mode when a solenoid is de-energized to a low displacement mode when the solenoid is energized, the high displacement mode being a default mode during the vehicle key-off state. In any or all of the foregoing examples, additionally or alternatively, indicating degradation of the VDOP includes estimating a first crankcase pressure during VDOP operation in the high displacement mode, and indicating that the VDOP is stuck in the low displacement mode in response to the first crankcase pressure being below a first baseline pressure. In any or all of the foregoing examples, additionally or alternatively, indicating degradation of the VDOP includes estimating a second crankcase pressure during VDOP operation in the low displacement mode, and indicating that the VDOP is stuck in the high displacement mode in response to the second crankcase pressure being below a second baseline pressure, the second baseline pressure being lower than the first baseline pressure. In any or all of the foregoing examples, additionally or alternatively, indicating degradation of the VDOP also includes indicating that the VDOP is stuck in the high displacement mode in response to a difference between the first crankcase pressure and the second crankcase pressure being below a threshold difference. In any or all of the foregoing examples, additionally or alternatively, each of the first crankcase pressure and the second crankcase pressure is estimated via a crankcase pressure sensor housed in a crankcase ventilation tube coupling the crankcase to the engine intake manifold. In any or all of the foregoing examples, the method further includes, additionally or alternatively, establishing a first baseline pressure via the crankcase pressure sensor by operating the VDOP in a high displacement mode while cranking the engine at idle speed without fuel when the VDOP is installed; and establishing a second baseline pressure via the crankcase pressure sensor by operating the VDOP in a low displacement mode while cranking the engine at idle speed without fuel when the VDOP is installed. In any or all of the foregoing examples, additionally or alternatively, adjusting the engine idle speed includes increasing the engine idle speed in response to the VDOP being stuck in the low displacement mode.

[0067] Another method for an engine includes: during a key-off state, estimating a first crankcase pressure while operating an oil pump in a high-displacement mode, indicating that the oil pump is stuck in a low-displacement mode based on the first crankcase pressure being lower than a first baseline pressure, and increasing an engine idle speed in response to the indication during a subsequent key-on state. In any of the foregoing examples, additionally or alternatively, the oil pump is a variable displacement oil pump, and wherein operating in the high-displacement mode includes deenergizing a solenoid. In any or all of the foregoing examples, the method further includes, additionally or alternatively, transitioning the pump from the high-displacement mode to the low-displacement mode by energizing the solenoid. In any or all of the foregoing examples, the method further includes, additionally or alternatively, after the transition, estimating a second crankcase pressure, and indicating that the oil pump is stuck in the high-displacement mode in response to the second crankcase pressure being higher than a second baseline pressure, the second baseline pressure being lower than the first baseline pressure. In any or all of the foregoing examples, additionally or alternatively, each of the first crankcase pressure, the second crankcase pressure, the first baseline pressure, and the second baseline pressure is estimated via a crankcase pressure sensor while rotating the engine without fuel via the electric motor during a vehicle key-off state. In any or all of the foregoing examples, the method further includes, additionally or alternatively, establishing each of the first baseline pressure and the second baseline pressure within a threshold duration of installation of an oil pump.

[0068] In yet another example, a hybrid vehicle system includes an engine; an electric motor coupled to a battery capable of rotating the engine; a crankcase including a variable displacement oil pump mechanically coupled to the engine; a solenoid configured to adjust the displacement of the oil pump; a crankcase ventilation tube mechanically coupled to an intake passage upstream of a compressor, the tube also mechanically coupled to the crankcase; a crankcase pressure sensor coupled to the crankcase ventilation tube; and a controller having computer-readable instructions stored on a non-volatile memory for commanding a change in displacement of the variable displacement oil pump via the solenoid during engine cranking without fuel via the electric motor, sensing crankcase pressure via the crankcase pressure sensor before and after the commanded change in displacement, and indicating degradation of the oil pump based on the sensed crankshaft pressure relative to a baseline pressure. In any of the foregoing examples, additionally or alternatively, the baseline pressure includes a first baseline pressure and a second baseline pressure, and the controller includes instructions for: establishing the first baseline pressure by rotating the engine via the electric motor when the oil pump is first installed and operating in high-displacement mode, and establishing the second baseline pressure by rotating the engine via the electric motor when the oil pump is first installed and operating in low-displacement mode. In any or all of the foregoing examples, additionally or alternatively, the commanded change in displacement is from high-displacement mode to low-displacement mode, and wherein indicating degradation of the oil pump includes: indicating that the pump is stuck in low-displacement mode with the solenoid de-energized in response to crankcase pressure sensed before the commanded change in displacement being below the first baseline pressure, and indicating that the pump is stuck in high-displacement mode with the solenoid energized in response to crankcase pressure sensed after the commanded change in displacement being above the second baseline pressure. In any or all of the foregoing examples, additionally or alternatively, the controller includes instructions for: increasing the engine idle speed in response to indicating that the pump is stuck in low-displacement mode.

[0069] Note that the exemplary control and estimation routines included herein can be used in conjunction with various engine and / or vehicle system configurations. The control methods and routines disclosed herein can be stored as executable instructions in a non-transitory memory and can be executed by a control system including a controller in conjunction with various sensors, actuators, and other engine hardware. The specific routines described herein can represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multi-tasking, multi-threaded processing strategies, etc. Therefore, the various actions, operations, or functions shown can be performed in the order shown, in parallel, or in some cases omitted. Likewise, the processing order is not necessarily required to achieve the features and advantages of the exemplary embodiments described herein, but is provided for ease of illustration and description. One or more of the actions, operations, and / or functions shown can be repeatedly performed depending on the specific strategy used. In addition, the actions, operations, and / or functions can graphically represent code programmed into the non-transitory memory of a computer-readable storage medium in the engine control system, where the actions are performed by executing instructions in a system including various engine hardware components in conjunction with an electronic controller.

[0070] It should be understood that the configurations and procedures disclosed herein are exemplary in nature, and these specific embodiments should not be construed in a limiting sense, as many variations are possible. For example, the above technology can be applied to V-6, I-4, I-6, V-12, opposed 4-cylinder, and other engine types. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations and other features, functions, and / or properties disclosed herein.

[0071] The following claims particularly point out certain combinations and subcombinations regarded as novel and non-obvious. These claims may refer to "an" element or "a first" element or the equivalent thereof. Such claims should be understood to include reference to one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed through amendment of the present claims or through presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, are also regarded as included within the subject matter of the present disclosure.

[0072] According to the present invention, a method is provided having the following features: indicating degradation of a variable displacement oil pump (VDOP) based on a change in estimated crankcase pressure as commanded VDOP displacement changes.

[0073] According to an embodiment, during immediately subsequent engine operation, engine idle speed is adjusted in response to an indication of VDOP degradation.

[0074] According to an embodiment, the above invention is further characterized by commanding a change in VDOP displacement during a vehicle key-off state when the engine temperature is substantially equal to the ambient temperature.

[0075] According to an embodiment, commanding a change in the VDOP displacement includes commanding the change while cranking the engine without fuel via the electric machine during a vehicle key-off state.

[0076] According to an embodiment, the above invention is further characterized in that the commanded change in VDOP displacement is from a high displacement mode when the solenoid is de-energized, which is the default mode during a vehicle key-off state, to a low displacement mode when the solenoid is energized.

[0077] According to an embodiment, indicating degradation of the VDOP includes estimating a first crankcase pressure during operation of the VDOP in the high displacement mode, and indicating that the VDOP is stuck in the low displacement mode in response to the first crankcase pressure being lower than a first baseline pressure.

[0078] According to an embodiment, the above invention is further characterized in that indicating degradation of the VDOP includes estimating a second crankcase pressure during operation of the VDOP in the low displacement mode, and indicating that the VDOP is stuck in the high displacement mode in response to the second crankcase pressure being lower than a second baseline pressure, the second baseline pressure being lower than the first baseline pressure.

[0079] According to an embodiment, indicating degradation of the VDOP further includes indicating that the VDOP is stuck in a high displacement mode in response to a difference between the first crankcase pressure and the second crankcase pressure being below a threshold difference.

[0080] According to an embodiment, the above invention is further characterized in that each of the first crankcase pressure and the second crankcase pressure is estimated via a crankcase pressure sensor housed in a crankcase ventilation tube coupling the crankcase to an engine intake manifold.

[0081] According to an embodiment, the above invention is also characterized in that a first baseline pressure is established via a crankcase pressure sensor by operating the VDOP in a high displacement mode while starting the engine at an idle speed without adding fuel when the VDOP is installed; and a second baseline pressure is established via the crankcase pressure sensor by operating the VDOP in a low displacement mode while starting the engine at an idle speed without adding fuel when the VDOP is installed.

[0082] According to an embodiment, adjusting the engine idle speed includes increasing the engine idle speed in response to the VDOP being stuck in the low displacement mode.

[0083] According to the present invention, a method for an engine is provided, the method having: during a key-off state, estimating a first crankcase pressure while operating an oil pump in a high-displacement mode; indicating that the oil pump is stuck in the low-displacement mode based on the first crankcase pressure being lower than a first baseline pressure; and during a subsequent key-on state, increasing an engine idle speed in response to the indication.

[0084] According to an embodiment, the oil pump is a variable displacement oil pump, and wherein operating in the high displacement mode includes de-energizing a solenoid.

[0085] According to an embodiment, the above invention is further characterized in that the pump is switched from the high displacement mode to the low displacement mode by energizing the solenoid.

[0086] According to an embodiment, after the transition, a second crankcase pressure is estimated, and an indication that the oil pump is stuck in the high displacement mode is given in response to the second crankcase pressure being higher than a second baseline pressure, the second baseline pressure being lower than the first baseline pressure.

[0087] According to an embodiment, each of the first crankcase pressure, the second crankcase pressure, the first baseline pressure, and the second baseline pressure are estimated via a crankcase pressure sensor while spinning the engine without fuel via an electric motor during a vehicle key-off state.

[0088] According to an embodiment, the above invention is further characterized in that each of the first baseline pressure and the second baseline pressure is established within a threshold duration of installation of the oil pump.

[0089] According to the present invention, a hybrid vehicle system is provided, which has: an engine; an electric motor connected to a battery and capable of rotating the engine; a crankcase including a variable displacement oil pump mechanically connected to the engine; a solenoid configured to adjust the displacement of the oil pump; a crankcase ventilation pipe mechanically connected to the intake passage upstream of the compressor, the pipe also being mechanically connected to the crankcase; a crankcase pressure sensor connected to the crankcase ventilation pipe; and a controller having computer-readable instructions stored on a non-volatile memory for performing the following items: commanding a displacement change of the variable displacement oil pump via the solenoid during engine cranking without fuel via the electric motor; sensing the crankcase pressure via the crankcase pressure sensor before and after the commanded change in displacement; and indicating degradation of the oil pump based on the sensed crankshaft pressure relative to a baseline pressure.

[0090] According to an embodiment, the baseline pressure includes a first baseline pressure and a second baseline pressure, and the controller includes instructions for: establishing the first baseline pressure by rotating the engine via the electric motor when the oil pump is first installed and operating in a high-displacement mode, and establishing the second baseline pressure by rotating the engine via the electric motor when the oil pump is first installed and operating in a low-displacement mode.

[0091] According to an embodiment, the commanded change in displacement is from a high displacement mode to a low displacement mode, and wherein indicating degradation of the oil pump includes indicating that the pump is stuck in the solenoid-deenergized low displacement mode in response to a crankcase pressure sensed before the commanded change in displacement being below a first baseline pressure, and indicating that the pump is stuck in the solenoid-energized high displacement mode in response to a crankcase pressure sensed after the commanded change in displacement being above a second baseline pressure.

Claims

1. A method for a vehicle, comprising: indicating degradation of a variable displacement oil pump (VDOP) based on a change in estimated crankcase pressure as commanded VDOP displacement changes; wherein the commanded change in VDOP displacement is from a high displacement mode when a solenoid is de-energized to a low displacement mode when the solenoid is energized, the high displacement mode being a default mode during a key-off state of the vehicle, and wherein indicating degradation of the VDOP includes estimating a first crankcase pressure during VDOP operation in the high displacement mode and indicating that the VDOP is stuck in the low displacement mode in response to the first crankcase pressure being less than a first baseline pressure; and Wherein commanding the change in VDOP displacement includes commanding the change while cranking an engine without fuel via an electric machine during the vehicle key-off state.

2. The method of claim 1 further comprising adjusting engine idle speed in response to said indication of said VDOP degradation during immediately subsequent engine operation.

3. The method of claim 2 further comprising commanding said change in VDOP displacement during a vehicle key-off state when engine temperature is substantially equal to ambient temperature.

4. The method of claim 1 , wherein indicating degradation of the VDOP comprises estimating a second crankcase pressure during VDOP operation in the low displacement mode, and indicating that the VDOP is stuck in the high displacement mode in response to the second crankcase pressure being lower than a second baseline pressure, the second baseline pressure being lower than the first baseline pressure. 5 . The method of claim 4 , wherein indicating degradation of the VDOP further comprises indicating that the VDOP is stuck in the high displacement mode in response to a difference between the first crankcase pressure and the second crankcase pressure being below a threshold difference.

6. The method of claim 4, wherein each of the first crankcase pressure and the second crankcase pressure is estimated via a crankcase pressure sensor housed in a crankcase ventilation tube coupling the crankcase to an engine intake manifold.

7. The method of claim 4 further comprising establishing the first baseline pressure via the crankcase pressure sensor by operating the VDOP in the high displacement mode while cranking the engine at engine idle speed without fuel when the VDOP is installed; and establishing the second baseline pressure via a crankcase pressure sensor housed in a crankcase vent tube by operating the VDOP in the low displacement mode while cranking the engine at engine idle speed without fuel when the VDOP is installed. 8 . The method of claim 1 , wherein adjusting the engine idle speed comprises increasing the engine idle speed in response to the VDOP being stuck in the low displacement mode.

9. A hybrid vehicle system comprising: engine; an electric motor coupled to the battery and capable of rotating the engine; a crankcase including a variable displacement oil pump mechanically coupled to the engine; a solenoid configured to adjust a displacement of the oil pump; a crankcase ventilation tube mechanically connected to the intake passage upstream of the compressor, the crankcase ventilation tube also being mechanically connected to the crankcase; a crankcase pressure sensor coupled to the crankcase ventilation tube; and A controller having computer-readable instructions stored on non-transitory memory to: switching the oil pump from a high displacement mode to a low displacement mode by energizing the solenoid; During the key-off state, spinning the engine without fuel via the electric motor; estimating a first crankcase pressure via the crankcase pressure sensor while operating the oil pump in the high displacement mode; indicating that the oil pump is stuck in a low displacement mode based on the first crankcase pressure being less than a first baseline pressure; and During a subsequent key-on state, the engine idle speed is increased in response to the indication.

10. The system of claim 9 wherein the controller further comprises instructions for, after the transition, estimating a second crankcase pressure via the crankcase pressure sensor and indicating that the oil pump is stuck in the high displacement mode in response to the second crankcase pressure being greater than a second baseline pressure, the second baseline pressure being lower than the first baseline pressure.

11. The system of claim 10, wherein the controller further comprises instructions for establishing each of the first baseline pressure and the second baseline pressure within a threshold duration of installation of the oil pump.

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