Detecting faults within the normal range in fuel pressure sensors

Abstract

Method for operating a fuel system (8) of an internal combustion engine with a pressure sensor (234) arranged downstream of a suction pump (208) for measuring a delivery pressure, comprising: During pulsed operation of the suction pump (208), the suction pump (208) is switched off when a detected delivery pressure increases to a desired peak pressure or when an on-time of the suction pump (208) reaches a calibrated maximum, and the suction pump (208) is switched on when either the detected delivery pressure decreases to a desired trough pressure or a volume of fuel consumed by the internal combustion engine reaches a predetermined volume, characterized in that in response to the fact that the on-time of the suction pump (208) reaches the calibrated maximum, indicating an error of the pressure sensor (234) within the normal range and initiating a calibration of the detected delivery pressure, wherein the calibration involves adding an offset to the detected delivery pressure and In response to the volume of fuel consumed by the internal combustion engine reaching the predetermined volume, indicating an error of the pressure sensor within the normal range and initiating a calibration of the detected delivery pressure, wherein the calibration involves subtracting an offset from the detected delivery pressure.

Description

AREA

[0001] The present description relates generally to a method for diagnosing a fault within the normal range of a pressure sensor located downstream of a fuel suction pump in an internal combustion engine, and adjusting the fuel system operation in response to the diagnosis. GENERAL STATE OF THE ART / BRIEF OVERVIEW

[0002] Internal combustion engines can include a fuel system with a fuel distributor for distributing fuel to one or more fuel injectors, which may be direct injectors and / or port injectors. In a direct injector fuel system, a fuel suction pump feeds fuel to a high-pressure fuel pump, which in turn delivers fuel at a high injection pressure to a fuel distributor. The fuel distributor is coupled to direct injectors that inject the fuel directly into the combustion chambers of the internal combustion engine. In a one-nozzle-per-port fuel system, a fuel suction pump feeds fuel at a lower injection pressure to a fuel distributor.The fuel distributor is coupled to the intake port injectors, which inject fuel upstream of the combustion chamber intake ports into the internal combustion engine intake. In a fuel system with one injector per intake port and direct injection, both single-injector per intake port and direct fuel injection are used.

[0003] Regardless of the type of fuel system, the fuel suction pump can be controlled to deliver fuel at a substantially constant delivery pressure during what is known as continuous pumping operation or continuous mode operation. This is achieved by applying a voltage with a 100% duty cycle and a voltage level corresponding to the desired constant delivery pressure. If the fuel flow demand changes, the voltage level can be adjusted and maintained at a different level (at a 100% duty cycle) to remain constant or substantially constant, resulting in a different, substantially constant, speed and delivery pressure of the suction pump.In contrast, the fuel suction pump can also be controlled to deliver intermittent pulses at relatively high pressure in what is known here as pulsed pump operation or pulsed mode, where the duty cycle of the voltage applied to the suction pump is less than 100%. During pulsed pump operation, the voltage level applied to the suction pump can alternate between a first, higher level and a second, lower level, with the second, lower level being very low (e.g., slightly above 0 V). During the first, higher voltage level applied to the suction pump, the pump speed and delivery pressure are high, whereas during the second, lower voltage level applied to the suction pump, the pump speed is very low (e.g., slightly above 0 V).at a level slightly above zero (which may be desirable to maintain the voltage supply to the suction pump instead of intermittently providing zero voltage), and the suction pump's discharge pressure is very low. Consequently, during pulsed operation, the suction pump's discharge pressure resembles a sawtooth wave over time, where the time between a trough of the wave and an adjacent peak of the wave following the trough is proportional to the duration of voltage application at the first, higher level, and where the time between a peak of the wave and an adjacent trough of the wave following the peak is proportional to the duration of voltage application at the second, lower level.

[0004] In contrast to continuous pump operation, pulsed pump operation, in which the fuel suction pump is only supplied with energy for the duration of each pulse, is more energy-efficient. Furthermore, using pulsed pump operation instead of continuous operation can extend the service life of the fuel suction pump and reduce maintenance costs.

[0005] When pulsed pump operation is implemented, the internal combustion engine control unit can perform either open-loop or closed-loop pump control. In open-loop control, voltage pulses with a predetermined pulse width (and thus a predetermined duty cycle) are applied to the suction pump, and a measured or derived pressure downstream of the fuel suction pump (referred to here as the suction pump delivery pressure) does not affect the control. In contrast, in closed-loop control, the delivery pressure is fed back to the control unit and affects the duration of subsequent high-voltage pulses applied to the suction pump (as well as the duration of the intervals between the high-voltage pulses when a voltage slightly above 0 V is applied).In examples where the delivery pressure is measured by a pressure sensor that provides feedback to the control system, a malfunction of the pressure sensor can shift the sensor reading, causing the delivery pressure to deviate from a desired or expected pressure, which in turn can affect the combustion engine operation. For example, faults within the expected normal range of the sensor output (referred to as in-range faults) are much more difficult to detect than faults outside the expected normal range of the sensor output (referred to as out-of-range faults). Detecting in-range faults is particularly critical when the sensor provides feedback for controlling pulsed pump operation with a closed-loop control system, as the fault leads to an incorrect setting of the voltage pulses applied to the suction pump.

[0006] An approach to addressing the detection of within-normal-range faults in fuel pressure sensors is disclosed by Stavnheim et al. in US 6,526,948 B1, which deals with diagnosing fuel pressure sensors that are "stuck" within the normal range. In this approach, a controller samples a fuel pressure sensor signal multiple times, including pressure peaks and troughs. The controller then calculates an average pressure value and compares the measured values ​​to this average. If a measured value falls within a threshold of the average, this indicates that the pressure sensor is stuck within the normal range (i.e., it does not respond dynamically to changes in fuel pressure), and the controller logs a fault code.If a certain number of errors are logged, the control system initiates a minimum fuel supply algorithm that provides just enough fuel to allow the vehicle to be driven out of a danger zone or to a maintenance center.

[0007] Document DE 10 2015 120 576 A1 discloses an optimization of an intermittent pump control in the operation of a fuel pump.

[0008] Document DE 10 2015 120 579 A1 discloses a method for identifying deterioration of the fuel system in internal combustion engines.

[0009] However, the inventors of the present invention have recognized potential problems with the approach described by Stavnheim et al. in US 6,526,948 B1. For example, the method described above is limited to detecting a malfunctioning pressure sensor that does not respond to pressure fluctuations. However, a malfunctioning pressure sensor may measure values ​​higher or lower than the actual pressure, yet still respond to pressure fluctuations. Furthermore, by providing just enough fuel to drive the vehicle out of the danger zone or to a service center after detecting a malfunctioning pressure sensor, the desired vehicle operation may not be available if the pressure sensor is malfunctioning, which could negatively impact driver satisfaction.

[0010] To address these problems, the inventors of the present invention have developed methods and systems for diagnosing pressure sensor faults within the normal range and adjusting fuel system operation based on the diagnosis. In one example, the problems described above can be addressed by a method for operating a fuel system of an internal combustion engine, comprising: during operation of a suction pump in pulsed mode, adjusting a voltage level applied to the suction pump based on an output signal from a pressure sensor downstream of the suction pump and monitoring the output signal for flattening; and, in response to the detection of flattening, indicating a pressure sensor fault and operating the suction pump independently of the pressure sensor output signal.In this way, faults occurring within the normal operating range of a pressure sensor located downstream of a fuel suction pump can be detected, and the fuel suction pump control can be switched from closed-loop to open-loop control after such faults are detected. While open-loop control of the suction pump may be less fuel-efficient than closed-loop control, this may not have a significant impact on driving performance.

[0011] To ensure the accuracy of the suction pump control and to diagnose pressure sensor faults within the normal range, the method may further include dynamically determining a setpoint pressure of a pressure relief valve and a fuel vapor pressure of the fuel system. This may involve the following: during steady-state operation of the internal combustion engine, when a requested delivery pressure of a fuel suction pump is below a first threshold, reducing the duty cycle of voltage pulses applied to a fuel suction pump until a flattening of an output signal from a pressure sensor downstream of the suction pump is detected, and storing the pressure at which the output signal has flattened as the fuel vapor pressure of the fuel system;During steady-state operation of the internal combustion engine, when the requested fuel suction pump delivery pressure exceeds a second threshold, the system increases the duty cycle of voltage pulses applied to the suction pump until a flattening of the pressure sensor output signal is detected. The pressure at which the output signal flattened is stored as the setpoint pressure of a pressure relief valve. The suction pump operation is then adjusted based on this stored setpoint pressure and the fuel vapor pressure. Dynamically determining the expected maximum and minimum physical values ​​of the fuel system in this manner can improve the overall accuracy of the fuel suction pump control and, in turn, improve the accuracy of pressure sensor fault diagnosis.

[0012] In yet another example, in accordance with the present disclosure, the suction pump can be controlled by a robust closed-loop control strategy. This can include: switching off the suction pump during pulsed operation when a detected discharge pressure increases to a desired peak pressure or when the pump's on-time reaches a calibrated maximum, and switching the suction pump ON when either the detected discharge pressure decreases to a desired trough pressure or the volume of fuel consumed by the internal combustion engine reaches a predetermined volume. Such operation can advantageously reduce the possibility of the suction pump "stuck" at a pressure below the setpoint when the pump is switched on, because the sensor measures values ​​that are too low, or at a pressure above the setpoint when the pump is switched off, because the sensor measures values ​​that are too high.Optionally, the robust control strategy can also include the following: calibrating a sensor output after detecting that the suction pump's on-time has reached a calibrated maximum or that the volume of fuel consumed by the combustion engine has reached a predetermined volume, so that accurate control of the suction pump can be carried out even if the sensor is impaired.

[0013] It is understood that the foregoing summary is provided to introduce, in simplified form, a selection of concepts that are further described in the detailed description. It is not intended to mention important or essential features of the claimed subject matter, the scope of which is defined solely in the claims following the detailed description. Furthermore, the claimed subject matter is not limited to implementations that remedy the disadvantages mentioned above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 schematically shows an exemplary embodiment of a cylinder in an internal combustion engine of a vehicle. Fig. Figure 2 schematically shows an exemplary embodiment of a fuel system that is integrated into the internal combustion engine. Fig. 1 can be used. Fig. Figures 3A-3E show curves illustrating the measured delivery pressure of a fuel suction pump as a function of time during pulsed pump operation of the fuel suction pump. Fig. Figure 4 shows a flowchart illustrating a routine for diagnosing a normal-range fault of a pressure sensor downstream of a fuel suction pump and controlling the operation of the fuel suction pump in response to the diagnosis. Fig. Figure 5A shows a flowchart illustrating a closed-loop fuel suction pump control routine. Fig. Figure 5B shows a flowchart illustrating a closed-loop fuel suction pump control routine in accordance with a first exemplary feedback control strategy, which is used in conjunction with the routine from Fig. 5A can be carried out. Fig. Figure 5C shows a flowchart illustrating a closed-loop fuel suction pump control routine in accordance with a second exemplary feedback control strategy, which is used in conjunction with the routine from Fig. 5A can be carried out. Fig. Figure 6 shows a flowchart illustrating a routine for setting the operation of a fuel system with a controller for determining a target pressure of a pressure relief valve and fuel vapor pressure of the fuel system. Fig. Figure 7 shows a flowchart illustrating a routine for diagnosing a fault within the normal range at the output of a pressure sensor downstream of a fuel suction pump. Fig. Figure 8 shows a characteristic map of exemplary curves of relevant signals during the adjustment of the operation of a fuel system with a control for determining a target pressure of a pressure relief valve and fuel vapor pressure of the fuel system in accordance with the routine from Fig. 6. Fig. Figure 9 shows a characteristic map of exemplary curves of relevant signals when a fault within the normal range occurs at the output of a pressure sensor downstream of a fuel suction pump in accordance with the routine from Fig. 7 is diagnosed, with the fault leading to a flattening of the valleys of the pressure sensor output signal. Fig. Figure 10 shows a characteristic map of exemplary curves of relevant signals when a fault within the normal range occurs at the output of a pressure sensor downstream of a fuel suction pump in accordance with the routine from Fig. 7 is diagnosed, whereby the fault leads to a flattening of the peaks of the pressure sensor output signal. Fig. Figure 11 shows a flowchart illustrating a routine for robust closed-loop control of a fuel suction pump. Fig. Figures 12A-12D show characteristic maps from exemplary curves of relevant signals during the robust control of a closed-loop fuel suction pump without calibration of the sensor output ( Fig. 12A and Fig. 12C) and with calibration of the sensor output ( Fig. 12B and Fig. 12D). In Fig. In 12A-12B, the sensor measures values ​​that are too low, whereas in Fig. 12C-12D measures excessively high values. DETAILED DESCRIPTION

[0014] The following description concerns systems and methods for controlling a fuel suction pump in a fuel system of an internal combustion engine, such as the one in Fig. 1. Internal combustion engine shown, as well as diagnosing a fault within the normal range of a pressure sensor located downstream of the fuel suction pump, and adjusting the operation of the fuel system in response to the diagnosis. As shown in Fig. As shown in Figure 2, the fuel system can include both port fuel injectors and direct fuel injectors and associated fuel distributors. However, the methods and systems described here are equally applicable to fuel systems that include port fuel injectors but no direct injectors, and to fuel systems that include direct injectors but no port fuel injectors, as well as to fuel systems that include other types of fuel injectors that draw pressurized fuel from a fuel suction pump. The suction pump can operate in a pulsed, closed-loop feedback mode (e.g., in accordance with the one shown in Figure 2). Fig. (routine shown in 5A-5C) by supplying voltage pulses to the suction pump until a desired fuel pressure is reached, measured by a pressure sensor downstream of the suction pump. Furthermore, a setpoint pressure of a fuel system pressure relief valve and a fuel vapor pressure within the fuel system can be dynamically determined at an internal combustion engine control unit by monitoring the detected pressure downstream of the suction pump, while in accordance with the routine shown in Fig. 6 routines shown and the one in Fig. Figure 8 shows the characteristic curve where the voltage applied to the suction pump is set (e.g., the duty cycle of voltage pulses applied to the suction pump is set). During the application of voltage pulses to the suction pump, the output signal of the pressure sensor downstream of the suction pump can exhibit a sawtooth waveform, for which an example is shown in Figure 8. Fig. Figure 3A shows that during a pressure sensor fault within the normal range, the sawtooth waveform may flatten at its peaks or troughs, depending on the nature of the fault, as shown in Figure 3A. Fig. 3B-3C shown. As in Fig. As shown in section 4, the controller can perform a routine in which the output signal of the pressure sensor downstream of the suction pump is monitored for flattening during pulsed pump operation with closed-loop control (e.g., in accordance with the [reference to be added]). Fig. 7 routine shown). In response to the detection of flattening, in accordance with the in Fig. 9 and Fig. In the characteristic curves shown, a pressure sensor error within the normal range is indicated, and the pump operation is switched from closed-loop control (where the pressure sensor feedback is included in the suction pump control) to open-loop control (where the pressure sensor feedback is not included in the suction pump control). Alternatively, the suction pump can be operated in accordance with the robust closed-loop control strategy, which is described in the routine from Fig. Figure 11 shows that this strategy can include switching off the suction pump if it has been switched on for a calibrated maximum on-time, even if the pressure sensor output has not yet reached a desired peak pressure, and switching on the suction pump if a volume of fuel that has been taken in since the suction pump was switched off reaches a predetermined volume, even if the pressure sensor output has not yet reached a desired trough pressure, as shown in Figure 11. Fig. 12A-12D shown. Optional, as shown in Fig. 12B and Fig. As shown in Figure 12D, the pressure sensor output can be calibrated if it has been determined that the sensor is measuring values ​​that are too high or too low, and the calibrated pressure sensor output can replace the pressure sensor output in the feedback control of the suction pump.

[0015] In this detailed description, one-nozzle-per-intake fuel injection can be abbreviated as PFI (port fuel injection), while direct injection can be abbreviated as DI (direct injection). A high-pressure pump can be abbreviated as HP pump (high pressure pump; alternatively HPP) or DI fuel pump. Similarly, a suction pump or fuel suction pump can also be referred to as a low-pressure pump (abbreviated as LP pump or LPP; low pressure pump). Furthermore, fuel rail pressure, or the pressure of fuel within a fuel rail, can be abbreviated as FRP (fuel rail pressure). The direct injection fuel rail can also be referred to as a high-pressure fuel rail, which can be abbreviated as HP fuel rail. For brevity, the set pressure of the pressure relief valve is referred to here as the set pressure.

[0016] Fig. Figure 1 shows an example of a combustion chamber or cylinder of the internal combustion engine 10, which may be enclosed in a motor vehicle 5. The internal combustion engine 10 may be controlled, at least partially, by a control system comprising the control unit 12 and by input from a driver 130 via an input device 132. In this example, the input device 132 includes an accelerator pedal and a pedal position sensor 134 for generating a proportional pedal position signal PP. The cylinder 14 (here also referred to as the combustion chamber 14) of the internal combustion engine 10 may include the combustion chamber walls 136 in which the piston 138 is positioned. The piston 138 may be coupled to the crankshaft 140, so that an alternating motion of the piston is translated into a rotational motion of the crankshaft. The crankshaft 140 may be coupled to at least one drive wheel of the passenger vehicle via a transmission system (not shown).Furthermore, a starter (not shown) can be coupled to the crankshaft 140 via a flywheel (not shown) to enable a starting process of the internal combustion engine 10.

[0017] Cylinder 14 can draw in intake air via a series of intake air ducts 142, 144, and 146. In addition to cylinder 14, intake air ducts 142, 144, and 146 can also be connected to other cylinders of the internal combustion engine 10. In some examples, one or more of the intake ducts may incorporate a charging device, such as a turbocharger or a supercharger. For example, [reference to relevant figure] shows Fig. 1. The internal combustion engine 10 is designed with a turbocharger comprising a compressor 174, arranged between the intake air ducts 142 and 144, and an exhaust turbine 176, arranged along an exhaust duct 158. The compressor 174 can be driven, at least partially, by the exhaust turbine 176 via a shaft 180 when the charging device is designed as a turbocharger. In other examples, such as when the internal combustion engine 10 is equipped with a supercharger, the exhaust turbine 176 can be optionally omitted, with the compressor 174 being driven by mechanical inputs from an electric motor or the internal combustion engine. A throttle 162, which includes a throttle valve 164, can be provided along an intake duct of the internal combustion engine to vary the flow rate and / or pressure of the intake air supplied to the cylinders of the internal combustion engine.For example, the throttle 162 can be positioned downstream of the compressor 174, as shown in . Fig. 1 shown, or alternatively it can be provided upstream of compressor 174.

[0018] The exhaust manifold 148 can receive exhaust gases from other cylinders of the internal combustion engine 10 in addition to those from cylinder 14. The exhaust gas sensor 128 is shown to be coupled to the exhaust duct 158 ​​upstream of the emission control device 178. The sensor 128 can be selected from various suitable sensors for providing an indication of an exhaust air-fuel ratio, such as a linear lambda sensor or UEGO sensor (universal exhaust gas oxygen sensor; wide-range or broadband lambda sensor), a dual-state lambda sensor or EGO sensor (as shown), a HEGO sensor (heated EGO sensor), or a NOx, HC, or CO sensor.

[0019] The emission control device 178 may be a three-way catalyst (TWC), a NOx trap, various other emission control devices, or combinations thereof.

[0020] Each cylinder of the internal combustion engine 10 can include one or more intake valves and one or more exhaust valves. For example, cylinder 14 is shown to include at least one intake control valve 150 and at least one exhaust control valve 156, which are arranged in an upper region of cylinder 14. In some examples, each cylinder of the internal combustion engine 10, which includes cylinder 14, can include at least two intake control valves and at least two exhaust control valves, which are arranged in an upper region of the cylinder.

[0021] The inlet valve 150 can be controlled by the controller 12 via the actuator 152. Likewise, the exhaust valve 156 can be controlled by the controller 12 via the actuator 154. Under certain conditions, the controller 12 can vary the signals provided to the actuators 152 and 154 to control the opening and closing of the corresponding inlet and exhaust valves. The position of the inlet valve 150 and exhaust valve 156 can be determined by appropriate valve position sensors (not shown). The valve actuators can be of the electric type, the cam type, or a combination thereof. The inlet and exhaust valve actuation can be controlled simultaneously, or any of the following options can be used: variable inlet cam actuation, variable exhaust cam actuation, dual independent variable cam actuation, or fixed cam actuation.Each cam actuation system can include one or more cams and use one or more cam profile switching (CPS), variable cam timing (VCT), variable valve timing (VVT), and / or variable valve lift (VVL) systems, which can be operated by the control unit 12, to vary the valve operation. For example, cylinder 14 can alternatively include an intake valve controlled by electric valve actuation and an exhaust valve controlled by cam actuation including CPS and / or VCT. In other examples, the intake and exhaust valves can be controlled by a common valve actuator or actuation system, or by a variable valve timing actuator or actuation system.

[0022] Cylinder 14 can have a compression ratio that is the volume ratio between piston 138 at bottom dead center and at top dead center. In one example, the compression ratio is in the range of 9:1 to 10:1. However, in some examples where different fuels are used, the compression ratio can be higher. This can occur, for example, when fuels with a higher octane rating or fuels with a higher latent heat of vaporization are used. The compression ratio can also be higher when using direct injection due to its effect on internal combustion engine knock.

[0023] In some examples, each cylinder of the internal combustion engine 10 may include a spark plug 192 to initiate combustion. The ignition system 190 can provide a spark to the combustion chamber 14 via the spark plug 192 in response to a spark advance signal SA from the control unit 12 under selected operating modes. However, in some embodiments, the spark plug 192 may be omitted, such as when the internal combustion engine 10 can initiate combustion by auto-ignition or by fuel injection, as may be the case with some diesel engines.

[0024] In some examples, each cylinder of the internal combustion engine 10 may be configured with one or more fuel injection devices to supply it with fuel. As a non-limiting example, cylinder 14 is shown to include two fuel injection devices 166 and 170. The fuel injection devices 166 and 170 may be configured to deliver fuel drawn from the fuel system 8. As shown below with reference to Fig. 2. The fuel system 8 can include one or more fuel tanks, fuel pumps and fuel distributors.

[0025] It is shown that the fuel injection device 166 is directly coupled to cylinder 14 to inject fuel directly into it, proportional to the pulse width of the signal FPW-1 received by the controller 12 via the electronic driver 168. In this way, the fuel injection device 166 provides direct injection of fuel into the combustion cylinder 14. While the injection device 166 is in Fig. 1 is shown positioned on one side of the cylinder 14, alternatively it can be located above the piston, such as near the position of the spark plug 192.

[0026] Such a position can improve mixing and combustion when the internal combustion engine is operated with an alcohol-based fuel, as some alcohol-based fuels have lower volatility. Alternatively, the injection device can be located above and near the intake valve to improve mixing. Fuel can be supplied to the fuel injection device 166 from a fuel tank of the fuel system 8 via a suction pump and / or a high-pressure fuel pump and a fuel distributor. Furthermore, the fuel tank can have a pressure converter that provides a signal to the control unit 12.

[0027] The fuel injection device 170 is shown in a configuration that provides fuel injection with one nozzle per intake port into the intake port upstream of cylinder 14, located in the intake air port 146 instead of in cylinder 14. The fuel injection device 170 can inject fuel taken from the fuel system 8 proportionally to the pulse width of the FPW-2 signal received by the controller 12 via the electronic driver 171. It should be noted that a single electronic driver 168 or 171 can be used for both fuel injection systems, or, as shown, multiple drivers can be used, for example, the electronic driver 168 for the fuel injection device 166 and the electronic driver 171 for the fuel injection device 170.

[0028] In an alternative example, each of the fuel injection devices 166 and 170 can be configured as a direct fuel injection device for injecting fuel directly into cylinder 14. In yet another example, each of the fuel injection devices 166 and 170 can be configured as an intake port fuel injection device for injecting fuel upstream of the intake valve 150. In still further examples, cylinder 14 can contain only a single fuel injection device, which is configured to receive different fuels in varying relative amounts as a fuel mixture from the fuel systems, and which is further configured to inject this fuel mixture either as a direct fuel injection device directly into the cylinder or as an intake port fuel injection device upstream of the intake valves.It is understood that the fuel systems described here are not to be limited by the specific designs of fuel injection devices described here as examples.

[0029] Fuel can be supplied to the cylinder by either injector during a single cylinder cycle. For example, each injector can provide a portion of the total fuel injection that is burned in cylinder 14. Furthermore, the distribution and / or relative amount of fuel supplied by each injector can vary with operating conditions such as combustion engine load, knocking, and exhaust gas temperature, as described below. Fuel injected by one nozzle per intake port can be supplied during an open intake valve event, a closed intake valve event (e.g., essentially before the intake stroke), and during operation with both open and closed intake valves.Similarly, directly injected fuel can be supplied, for example, during an intake stroke, partially during a preceding exhaust stroke, during the intake stroke, and partially during the compression stroke. Thus, even in a single combustion event, injected fuel can be injected from the intake port and direct injection device at different times. Furthermore, multiple injections of the supplied fuel can be performed per cycle for a single combustion event. These multiple injections can occur during the compression stroke, the intake stroke, or any suitable combination thereof.

[0030] As described above, shows Fig. 1 merely one cylinder of a multi-cylinder engine. Accordingly, each cylinder can equally contain its own set of intake / exhaust valves, fuel injection device(s), spark plug, etc. It is understood that the internal combustion engine 10 can contain any suitable number of cylinders, including 2, 3, 4, 5, 6, 8, 10, 12 or more cylinders. Furthermore, each of these cylinders can contain some or all of the various components that are in Fig. 1 are described and illustrated with reference to cylinder 14.

[0031] The fuel injection devices 166 and 170 can have different characteristics. These include differences in size; for example, one injection device may have a larger injection orifice than the other. Other differences include, but are not limited to, different spray angles, different operating temperatures, different target orientations, different injection timings, different spray characteristics, different positions, etc. Furthermore, different effects can be achieved depending on the distribution ratio of the injected fuel between the injection devices 170 and 166.

[0032] Control 12 is in Fig. 1 is shown as a microcomputer comprising a microprocessor unit 106, input / output ports 108, an electronic storage medium for executable programs and calibration values, which in this specific example is shown as a non-volatile read-only memory chip 110 for storing executable instructions, random access memory 112, keep-alive memory 114 and a data bus.In addition to the signals discussed previously, the control unit 12 can receive various signals from sensors coupled to the internal combustion engine 10, including the measurement of mass air flow (MAF) from a mass air flow sensor 122; the engine coolant temperature (ECT) from a temperature sensor 116 coupled to a cooling sleeve 118; a profile ignition pickup signal (PIP) from a Hall effect sensor 120 (or other type) coupled to the crankshaft 140; the throttle position (TP) from a throttle position sensor; and a manifold absolute pressure (MAP) signal from a sensor 124. The MAP signal can be used to provide an indication of vacuum or pressure in the intake manifold. An internal combustion engine speed signal (RPM) can be generated by the control unit 12 from the PIP signal.

[0033] In some examples, the vehicle 5 can be a hybrid vehicle with multiple torque sources available to one or more vehicle wheels 55. In other examples, the vehicle 5 is a conventional vehicle with only an internal combustion engine or an electric vehicle with only one electric machine. In the example shown, the vehicle 5 includes an internal combustion engine 10 and an electric machine 52. The electric machine 52 can be an electric motor or an electric motor / generator. The crankshaft 140 of the internal combustion engine 10 and the electric machine 52 are connected to the vehicle wheels 55 via the transmission 54 when one or more clutches 56 are engaged. In the example shown, a first clutch 56 is provided between the crankshaft 140 and the electric machine 52, and a second clutch 56 is provided between the electric machine 52 and the transmission 54.The control unit 12 can send a signal to an actuator of each clutch 56 to engage or disengage the clutch, thereby connecting or disconnecting the crankshaft 140 from the electric machine 52 and its associated components, and / or connecting or disconnecting the electric machine 52 from the transmission 54 and its associated components. The transmission 54 can be a manual transmission, a planetary gear system, or another type of transmission. The powertrain can be configured in various ways, including as a parallel, in-line, or in-line-parallel hybrid vehicle.

[0034] The electric power from a traction battery 58 is used to provide torque to the vehicle wheels 55. The electric machine 52 receives electrical power. The electric machine 52 can also be operated as a generator, for example, to provide electrical power for charging the battery 58 during braking.

[0035] Fig. Figure 2 schematically represents an exemplary embodiment of the fuel system 8. Fig. 1. The actuators of the fuel system 8 can be controlled by a controller, such as the controller 12. Fig. 1. be operated to carry out some or all of the activities referred to in Fig. to carry out the processes described in the exemplary routines shown in 4-7.

[0036] The fuel system 8 can be used with an internal combustion engine, such as the exemplary internal combustion engine 10. Fig. 1. Supply fuel from a fuel tank 202. In the illustrated embodiment, the fuel system is a PFDI fuel system and thus includes a first low-pressure fuel distributor 240, which supplies fuel to one or more port fuel injectors 242, and a second high-pressure fuel distributor 250, which supplies fuel to one or more direct fuel injectors 252. In other examples, however, the fuel system 8 can be a PFI or DI fuel system. For example, the fuel can contain one or more hydrocarbon components and optionally an alcohol component. The fuel can be supplied to the fuel tank 202 via a fuel filling channel 204.

[0037] A fuel suction pump (LPP) 208, in conjunction with the fuel tank 202, can be operated to supply fuel from the fuel tank 202 to a first fuel channel 230. As shown, the first fuel channel 230 has a first end coupled to the outlet of the suction pump and a second end coupled to the first fuel distributor, so that fuel pumped into the first fuel channel by the LPP can be supplied to the first fuel distributor 240 and thus to the inlet port injection devices 242. In one example, the LPP 208 can be electrically driven and located at least partially within the fuel tank 202. As shown, a check valve 209 can be positioned downstream of an outlet of the LPP 208.The check valve 209 can allow fuel flow from the LPP 208 to the first fuel channel 230, while blocking fuel flow in the opposite direction from the first fuel channel 230 back to the LPP 208. The pressure downstream of the check valve 209 can differ from the pressure downstream of the LPP 208 and upstream of the check valve 209; references to the pressure in the first fuel channel here refer to the pressure in the first fuel channel downstream of the check valve 209.

[0038] A pressure relief valve 211 can be included in the fuel system to release excess pressure. In the illustrated example, the pressure relief valve 211 is arranged in a channel 231, which has a first end coupled to the first fuel channel 230 and a second end coupled to the fuel tank 202, to allow fuel to flow back from the first fuel channel 230 to the fuel tank 202 if the pressure of the fuel system exceeds a set pressure of the pressure relief valve.The pressure relief valve can be a passive valve that opens and closes depending on the fluid pressure to which it is subjected; alternatively, the pressure relief valve can be an actively controlled valve, and the controller can send a signal to an actuator of the pressure relief valve to open or close the valve depending on a fluid pressure, such as the delivery pressure of the fuel system. The set pressure is the pressure at which the pressure relief valve passively opens (or is actively opened) to release pressure from the fuel system (e.g., by returning fuel to the fuel tank). The set pressure value can be determined by the geometry of the pressure relief valve or varied by an actuator of the pressure relief valve in response to a signal from the controller.

[0039] Although it has been shown that the first fuel distributor 240 supplies fuel to four intake port injectors 242, it is understood that the first fuel distributor 240 can supply fuel to any suitable number of fuel injectors. For example, the first fuel distributor 240 can supply fuel to one of the intake port injectors 242 for each cylinder of the internal combustion engine. In other examples, the first fuel channel 240 can supply fuel to the intake port injectors 242 via two or more first fuel distributors. For example, if the cylinders of the internal combustion engine are arranged in a V-configuration, the first fuel channel can lead to two first fuel distributors, each of which can supply fuel to the respective intake port injectors.

[0040] In the illustrated example, a second fuel channel 232 branches off from the first fuel channel upstream of the first fuel distributor. One end of the second fuel channel is connected to the first fuel channel upstream of the first fuel distributor, while the other end of the second fuel channel is connected to the second fuel distributor. A high-pressure fuel pump (HPP) 228, which receives fuel pumped from the fuel tank by the low-pressure fuel pump (LPP) 208, is located in the second fuel channel 232. In one example, the HPP 228 can be a mechanically driven positive displacement pump. The HPP 228 can be connected to the direct fuel injection devices 252 via the second fuel distributor 250.Fuel pumped into the first fuel channel 230 by the LPP 208 can be pumped from the first fuel channel 230 into the second fuel channel 232 by the HPP 228 and further pressurized by the HPP pump 228 before flowing to the first fuel distributor 250 for direct injection into the internal combustion engine via the direct fuel injection devices 252. The second fuel distributor 250 can be a high-pressure fuel distributor; for example, fuel in the second fuel distributor 250 can be stored at a higher pressure than the pressure of the fuel stored in the first fuel distributor 240, since the fuel is further pressurized at the HPP 228.

[0041] The various components of the fuel system 8 are connected to an internal combustion engine control system, such as the control unit 12. For example, the control unit 12 can receive data from various sensors related to the fuel system 8, in addition to the sensors mentioned above with reference to Fig. The controller 12 receives signals indicating operating conditions as described in section 1. These signals may include signals from one or more pressure sensors located in the fuel system, such as pressure sensors 234, 235, and 236. The signals may also include a signal from a fuel level sensor 206 indicating the quantity of fuel stored in the fuel 202. Additionally, the controller 12 may receive signals from one or more fuel composition sensors, in addition to or as an alternative to a fuel composition indication based on a signal from an exhaust gas sensor (such as sensor 128). Fig. 1) is derived, receives signals indicating the fuel composition. For example, an indication of the fuel composition of the fuel stored in the fuel tank 202 can be provided by the fuel composition sensor 210. The fuel composition sensor 210 can further include a fuel temperature sensor. Additionally or alternatively, one or more fuel composition sensors can be provided at any suitable location along the fuel channels between the fuel storage tank and the fuel injection devices.

[0042] In the Fig. In the example shown, the fuel system comprises a pressure sensor 236 coupled to the second fuel distributor 250, and one or more pressure sensors 234 coupled to the first fuel channel 230 and 235 coupled to the first fuel distributor 240. Pressure sensor 234 can be used to determine the fuel line pressure of the first fuel channel 230 downstream of the suction pump and thus the delivery pressure of the suction pump. Pressure sensor 235 can be used to measure the pressure level within the first fuel distributor 240. Pressure sensor 236 can be used to measure the pressure level in the second fuel distributor 250. The positions of the sensors in the example are shown in the example. Fig. The two pressure sensors shown are for illustrative purposes only and are not limiting; instead of or in addition to the pressure sensors shown, other pressure sensors can be positioned in the fuel system 8 to measure the pressure at different points within it. The various measured pressures can be transmitted as signals to the controller 12. In some examples, other types of sensors can be arranged at different points in the fuel system 8, and pressures within the fuel system can be derived based on the output of these sensors.

[0043] In the sense used here, the term "delivery pressure" refers to the fuel pressure downstream of the suction pump, in particular downstream of the check valve 209 in the exemplary fuel system from Fig. 2 and upstream of any DI pump or other type of pump that may be included in the system. In an example where the fuel system includes a pressure sensor in the first fuel channel (e.g., pressure sensor 234) and no pressure sensor in the first fuel distributor, the delivery pressure refers to the pressure measured in the first fuel channel. In an example where the fuel system includes a pressure sensor in the first fuel distributor (e.g., pressure sensor 235) but no pressure sensor in the first fuel channel, the delivery pressure refers to the pressure in the first fuel distributor. In an example where the fuel system includes a pressure sensor in both the first fuel channel and the first fuel distributor, the delivery pressure may refer to only one of the pressures in the first fuel channel and the other of the pressures in the first fuel distributor.

[0044] The controller 12 is designed to control the operation of each of the LPP 208 and HPP 228 to adjust the quantity, pressure, flow rate, etc., of fuel supplied to the internal combustion engine. For example, the controller 12 can vary the pressure setting, pump stroke quantity, pump duty cycle command, and / or fuel flow rate of the fuel pumps to supply fuel to different points in the fuel system. During both single-nozzle-per-intake and direct injection, the LPP 208 can be controlled by the controller 12 to supply fuel to the first fuel distributor 240 and / or the HPP 228 based on the pressure in one or more of the first fuel channel, the first fuel distributor, and the second fuel distributor. A driver electronically coupled to the controller 12 can be used to send a control signal to the LPP 208 to determine the output (e.g.,The speed and / or delivery pressure of the LPP 208 can be adjusted. During direct injection, the amount of fuel supplied to the direct fuel injection devices via the HPP 228 can be adjusted by setting and coordinating the output of the LPP 208 and HPP 228.

[0045] The controller 12 can control the LPP 208 to operate in either continuous or pulsed mode. Similarly, the controller 12 can control the HPP 228 to operate in either continuous or pulsed mode. During continuous operation of the LPP 208, a constant non-zero voltage is applied to the suction pump to supply fuel to the first fuel distributor 240 at a constant fuel pressure. The HPP 228 can operate in continuous mode in a similar manner. Conversely, during pulsed operation of the LPP 208, the LPP can be activated (i.e., switched ON), but supplied with zero voltage or a voltage slightly higher than zero. In this case, higher-voltage pulses can be applied to the LPP 208.During the application of each higher voltage pulse, the voltage supplied to the LPP is increased from a lower positive voltage (e.g., 0 V or essentially 0 V) ​​to a higher positive voltage (e.g., 8-12 V), held at the higher voltage for a duration (e.g., 30-300 ms), and then reduced from the higher voltage back to the lower voltage.

[0046] In accordance with a first exemplary feedback control strategy, the duty cycle of the voltage pulses is fixed. This duty cycle determines the relative duration of the lower and higher voltages applied to the suction pump (and thus the pulse width). In such cases, a higher voltage to be supplied to the suction pump can be selected based on the fixed duty cycle (which specifies the duration of the higher-voltage pulses). For example, the LPP 208 can be pulsed at 8 V if the interval between the higher-voltage pulses (during which the lower voltage is supplied) is between 0 and 50 milliseconds. Alternatively, if the interval between the higher-voltage pulses is between 50 and 100 milliseconds, the LPP 208 can be pulsed at 10 V.In another example, the LPP 208 can be pulsed with 12 V if the interval between the higher voltage pulses is between 100 and 250 milliseconds.

[0047] In contrast, in a second exemplary feedback control strategy, the LPP is switched ON (e.g., operated with a high voltage) when it is detected that a desired valley delivery pressure has been reached, and switched OFF (e.g., operated with a voltage close to 0 V) ​​when it is detected that a desired peak delivery pressure has been reached.

[0048] Operating the LPP in pulsed mode can effectively ensure lower energy consumption while providing a faster response time when the LPP is activated. Furthermore, operating in pulsed mode can improve the lifespan of the LPP 208. Operating the HPP 228 in pulsed mode can be done similarly.

[0049] A pump electronics module (PEM) of the LPP 208 can supply electrical power to an electric motor coupled to the LPP. In one example, a controller, such as the controller 12, reads the data from the pump electronics module. Fig. 1. The output of a fuel pressure sensor, which detects the delivery pressure of the LPP (low-pressure pump), is received, and a fuel pump command (FPC) is sent to the PEM (power electronic module). This command varies with and is determined based on the fuel pressure sensor output, among other factors. The FPC can be encoded as a 150 Hz duty cycle, transmitting, for example, the intended duty cycle of a field-effect transistor (FET) in the LPP to the PEM. Alternatively, the PEM can transmit the FPC via a serial interface, such as a CAN bus or LIN bus. The PEM takes the commanded FET duty cycle and applies it to the FET at a frequency such as 9.8 kHz. This results in an effective voltage being applied to the pump's brushed DC motor.If the vehicle's power supply is 12 V and the desired effective voltage applied to the LPP is 6 V, the FET can be switched on for 0.00005 seconds and off for 0.00005 seconds (i.e., operated at a 50% duty cycle). The PEM current has a certain value; the pump motor current is generally a current that, due to current circulation through a diode while the FET is off, is on average larger than the average current of the PEM. (The instantaneous current of the PEM is essentially equal to the instantaneous current of the pump motor while the FET is switched on. While the FET is off, the instantaneous current of the PEM is zero, but the current through the electric motor's inductance is positive.) The PEM draws its electrical energy from the vehicle battery, which can be a 12 V battery, and the vehicle's alternator system.If no measures are taken for current shaping or soft starting, the peak PEM current will be, for example, 30 to 35 amperes. However, by not immediately applying a full step voltage of the full battery / alternator voltage, the peak value of this inrush current can be reduced, for example, to the level of the steady-state current. For instance, the effective voltage applied to the pump motor can be shaped so that the peak inrush current remains below 10 amperes.

[0050] When the LPP 208 is operated in pulsed mode, a sawtooth pressure pattern can be observed in the delivery pressure, which, with reference to Fig. 3A-3C is discussed in more detail. For example, the pulsed mode can generate a rapid pressure rise to 6.5 bar, followed by a downward slope to 4.5 bar as fuel is consumed. While this pressure change may not be used in direct injection systems, knowing the current pressure may be desirable in PFI systems.

[0051] In continuous operating mode, the control of the LPP (e.g., the control of the voltage level applied to the LPP) can be a closed-loop control based on feedback from one or more pressure sensors (e.g., pressure sensors 234, 235, and 236) or an open-loop control that operates independently of the pressure sensor feedback and does not take it into account. Similarly, in pulsed continuous operating mode, the control of the LPP (e.g., the control of the voltage level and / or duty cycle of the pulses applied to the LPP) can be a closed-loop control based on feedback from one or more pressure sensors (e.g., pressure sensors 234, 235, and 236) or an open-loop control that operates independently of the pressure sensor feedback and does not take it into account.If the LPP 208 is pulsed independently of the feedback, it can be operated at a slightly higher power than required. Despite the slightly higher power supplied to the LPP 208 during operation in pulsed mode without feedback, the LPP effectively consumes significantly less power in pulsed mode without feedback compared to the power consumption during continuous operation of the suction pump.

[0052] Fig. Figures 1-2 show exemplary layouts with a relative positioning of the various components. If such elements are shown in direct contact or are directly coupled, they can be described as directly contacting or directly coupled, respectively, in at least one example. Similarly, elements shown abutting or adjacent to each other can be described as abutting or adjacent, respectively, in at least one example. For instance, components that share a surface in contact with each other can be described as having surface-sharing contact. As another example, elements positioned separately from each other, with only a space between them and no other components, can be described as such in at least one example.As a further example, elements depicted above / below each other, on opposite sides, or to the left / right of each other can be described as such relative to one another. Furthermore, as shown in the figures, a topmost element or the highest point of an element can be described as the "top" of the component in at least one example, and a bottommost element or the lowest point of the element can be described as the "bottom" of the component. In the sense used here, top / bottom, upper / lower, and above / below can refer to a vertical axis of the figures and be used to describe the positioning of elements of the figures relative to one another. Accordingly, elements shown above other elements are, in one example, positioned vertically above the other elements.As a further example, the shapes of the elements depicted in the figures can be described as having these shapes (such as circular, straight, flat, curved, rounded, beveled, angled, or the like). Furthermore, elements shown to intersect each other can be described, in at least one example, as intersecting elements or as intersecting each other. Even further, an element shown inside or outside another element can be described as such, in one example.

[0053] Fig. Figures 3A-3E represent curves that show the measured and actual delivery pressure of a fuel suction pump (e.g., the LPP 208 from Fig. 2) Illustrate during pulsed operation as a function of time. Fig. Figure 3A illustrates a waveform representing both the detected and the actual pressure during pulsed operation when a pressure sensor detecting the conveying pressure is functioning properly. Fig. Figure 3B illustrates two waveforms representing the detected and actual delivery pressure during pulsed operation with the first exemplary feedback control strategy when the pressure sensor detecting the delivery pressure is impaired and measures excessively high values. Fig. Figure 3C illustrates two waveforms representing the detected and actual delivery pressure during pulsed operation with the first exemplary feedback control strategy when the pressure sensor detecting the delivery pressure is impaired and measures values ​​that are too low. Fig. 3D illustrates two waveforms representing the detected and actual delivery pressure during pulsed operation with the second exemplary feedback control strategy when the pressure sensor detecting the delivery pressure is impaired and measures excessively high values. Fig. Figure 3E illustrates two waveforms representing the detected and actual delivery pressure during pulsed operation with the second exemplary feedback control strategy when the pressure sensor detecting the delivery pressure is impaired and measures values ​​that are too low.

[0054] As in Fig. As shown in Figures 3A-3E, applying voltage pulses to a fuel suction pump results in delivery pressures that produce a waveform with a sawtooth pattern when plotted against time. In some examples, during pulsed operation of the suction pump, in accordance with the first exemplary feedback control strategy, the duty cycle of the pulses applied to the suction pump (and optionally the level of the supply voltage) is selected (e.g., pre-programmed into the controller, dynamically determined at the controller, or determined at the controller based on internal combustion engine operating conditions) such that the application of each supply voltage pulse to the suction pump produces a rapid rise in delivery pressure until a desired peak pressure is reached.In accordance with the second exemplary feedback control strategy, a predetermined high voltage is applied to the suction pump when it is detected that a desired trough discharge pressure has been reached, whereas a predetermined low voltage (e.g., 0 V or slightly more than 0 V) ​​is applied to the suction pump when it is detected that a desired peak discharge pressure has been reached, so that the detected discharge pressure determines the duration of each pulse with the higher voltage. It is understood that other feedback control strategies may be used without deviating from the scope of this disclosure.

[0055] In the Fig. In the examples shown in 3A-3E, the desired peak pressure (represented by the dashed line 307) was chosen to be below the setpoint pressure of the pressure relief valve (represented by the dashed line 302), and the desired trough pressure (represented by the dashed line 305) was chosen to be above the fuel vapor pressure (represented by the dashed line 304). The setpoint pressure and the fuel vapor pressure can represent the maximum and minimum physical pressures of the fuel system, respectively. For example, as above, with reference to Fig. Section 2 discusses the target pressure as the pressure at which the pressure relief valve opens to release pressure from the fuel system (e.g., by returning fuel to the fuel tank). Furthermore, the fuel exists in thermodynamic equilibrium between its gaseous and liquid phases, with the fuel vapor present at a specific pressure (e.g., vapor pressure) that depends on the fuel composition and temperature. In the absence of additional fuel supply from the suction pump while fuel is being injected by the fuel injectors, the delivery pressure decreases to the fuel vapor pressure and cannot decrease further. The fuel vapor pressure can vary from near zero absolute pressure at cold ambient temperatures to over 600 kPa absolute pressure during warm starts.Fuel vapor pressure is the minimum pressure that can be achieved in the fuel system as long as liquid fuel is present, which is always the case in real vehicles. Undissolved air may also be present in the line, which makes the pressure slightly higher than the fuel vapor pressure, but the fuel vapor pressure still determines the minimum pressure.

[0056] Driving the suction pump motor causes the delivery pressure to increase to such an extent that, when plotted against time, the delivery pressure ultimately appears as an upward slope. When the suction pump motor is off and the voltage applied to the suction pump is essentially 0 V, and fuel is injected at a constant rate from this low-pressure zone via PFI or pumped via DI, the delivery pressure ultimately appears as a downward slope when plotted against time. If fuel consumption (via PFI injection or DI pumping) increases, the downward slope becomes steeper, and vice versa.

[0057] In the Fig. In the exemplary diagram 300 shown in Figure 3A, the feedback control of the suction pump functions correctly, and the pressure sensor that detects the delivery pressure measures accurate values ​​(it is, for example, not impaired). Because the pressure sensor measures accurate values, the signal output from the pressure sensor accurately represents the actual delivery pressure. Accordingly, the waveform 306, which has a sawtooth pattern, represents both the signal output from the pressure sensor and the actual delivery pressure. As shown, the waveform 306 exhibits peaks 306a at a desired peak pressure (represented by the dashed line 307) that is lower than the set pressure 302 of the pressure relief valve (thus providing a margin between the peak pressure and the set pressure). Furthermore, the waveform 306 exhibits troughs 306b at a pressure higher than the fuel vapor pressure 304.In other examples, however, the desired peak pressure may be set to the target pressure and / or the duty cycle of the pulses may be set such that the troughs of the waveform are equal to the fuel vapor pressure.

[0058] In contrast, the pressure sensor is located in the Fig. The exemplary diagram 320 shown in Figure 3B is affected and measures values ​​that are too high compared to the actual delivery pressure (represented by waveform 308). In this example, the first exemplary feedback control strategy is implemented. Accordingly, waveform 309 has the same shape as waveform 308, but it is shifted upwards in the diagram because the controller adjusts the voltage pulses applied to the suction pump in response to the (higher) detected delivery pressure. Specifically, the controller has reduced the duty cycle of the voltage pulses applied to the suction pump relative to the duty cycle that would have been selected with an accurate sensor reading.As a result, insufficient voltage is supplied for the actual delivery pressure (waveform 308) to reach the desired peak pressure 307, and the actual delivery pressure decreases relative to the delivery pressure during sensor operation at nominal pressure (e.g. as shown by waveform 306). Fig. (3A shown). Furthermore, in the illustrated example, the actual delivery pressure has decreased to such an extent that, after the application of a voltage pulse to the suction pump during fuel injection by fuel injection devices, the pressure on the fuel vapor pressure decreases and remains at the fuel vapor pressure for a period of time (e.g., until it begins to increase again due to the application of the next voltage pulse), so that the waveform 308 appears flattened at each trough. The troughs flatten because the actual pressure cannot fall below the fuel vapor pressure 304, which is the physical minimum value of the system.This flattening contrasts with the pressure characteristic of the actual delivery pressure when the sensor is functioning correctly, where the actual delivery pressure continues to decrease until the next voltage pulse is applied. This results in a sharp transition of the pressure signal from a negative slope to a positive slope at the valley pressure, such that, for example, the pressure signal remains at its minimum value for less than a threshold duration. The normal, sharp valleys that would occur for waveform 308 if the pressure could drop below the fuel vapor pressure are shown by dashed lines. Similar to waveform 308, waveform 309 appears flattened at each valley, but the flattening occurs at a measured pressure higher than the fuel vapor pressure because the sensor is measuring values ​​that are too high.

[0059] In the Fig. In the exemplary diagram 330 shown in Figure 3C, the pressure sensor in the fuel line is malfunctioning and measures values ​​that are too low compared to the actual delivery pressure (represented by waveform 310). Here, the first exemplary feedback control strategy is applied again. Accordingly, waveform 311 has the same shape as waveform 310, but it is shifted downwards in the diagram. In this case, the controller adjusts the voltage pulses applied to the suction pump in response to the (lower) detected delivery pressure by increasing the duty cycle of the voltage pulses applied to the suction pump relative to the duty cycle that would have been selected if the signal provided by the pressure sensor had been correct.As a result, the actual delivery pressure (waveform 310) increases overall relative to the delivery pressure during sensor operation at nominal pressure (e.g. as shown by waveform 306). Fig. (3A shown). Therefore, the LPP 208 receives more voltage than is required to achieve the desired peak pressure, which is undesirable because it reduces efficiency and increases power consumption. As shown, the peaks of waveform 310 are at a higher pressure than the desired peak pressure 307. Furthermore, in the example shown, the actual delivery pressure has increased to such an extent that when a voltage pulse is applied to the suction pump, the pressure increases to the set pressure of the pressure relief valve. The voltage then remains for a certain period (e.g., until it begins to decrease again due to fuel injection by the fuel injectors / pumping by the DI pump), so that waveform 310 appears flattened at each peak.This contrasts with the pressure characteristic of the actual delivery pressure when the sensor is functioning correctly. The actual delivery pressure continues to increase until fuel is consumed via the injection of fuel into the combustion engine by the fuel injectors. This results in a sharp transition of the pressure signal from a positive slope to a negative slope at the peak pressure, such that, for example, the pressure signal remains at its maximum value for less than a threshold duration. The peak flattens because the actual pressure cannot exceed the set pressure 302. The normal, unflattened peaks that would occur if the pressure could exceed the set pressure are shown by dashed lines.Similar to waveform 310, waveform 311 appears flattened at each peak, but the flattening occurs at a measured pressure that is lower than the target pressure because the sensor is measuring values ​​that are too low.

[0060] In the sense used here, "flattening" of the measured discharge pressure and the actual discharge pressure refers to an event in which the pressure waveform transitions from a non-zero slope to a zero slope and remains at zero slope for more than a threshold duration (e.g., remains constant). For example, the measured pressure for a valley (as in Fig. (shown in 3B) transition from a negative slope to a zero slope and then to a positive slope or for a peak (as in Fig. (3C shown) conversely, whereby in each case it remains at zero slope for a threshold duration. The threshold duration can be predetermined during the manufacture of the internal combustion engine and stored in non-volatile memory of the control system. Furthermore, the threshold duration can be proportional to the duty cycle of the voltage pulses applied to the suction pump and, in particular, shorter than the duration (pulse width) of each voltage pulse. The flattening of the pressure waveform can alternatively be described as the truncation of the waveform at its peaks and troughs or the plateau formation of the waveform at its maximum and minimum values.

[0061] While the in Fig. The exemplary diagrams shown in 3B-3C for the pulsed operation of the LPP in accordance with the first exemplary feedback control strategy belong to those in Fig. The exemplary diagrams shown in 3D-3E illustrate the pulsed operation of the LPP in accordance with the second exemplary feedback control strategy. In the Fig. In the 3D example diagram 340, the pressure sensor is malfunctioning and is measuring values ​​that are too high compared to the actual delivery pressure (represented by waveform 312). In this example, the second example feedback control strategy is implemented. At the beginning of the curve, the delivery pressure decreases because only a minimal voltage (e.g., slightly above 0) is applied to the suction pump, and fuel injection occurs. If the pressure sensor were functioning correctly, it would accurately detect that the actual delivery pressure reaches the desired valley pressure, and at this point, the controller would increase the voltage applied to the suction pump.However, because the pressure sensor measures values ​​that are too high, the controller does not increase the voltage applied to the suction pump to a higher voltage when the actual delivery pressure reaches the desired valley pressure. As shown, the measured delivery pressure is still above the desired valley pressure at this point, and therefore the pulsing of the suction pump to the higher voltage is not triggered. The actual delivery pressure thus continues to decrease until the measured delivery pressure reaches the desired valley pressure. In the example shown, due to the extent to which the pressure sensor measures values ​​that are too high, the actual delivery pressure decreases to the fuel vapor pressure before the measured delivery pressure has decreased to the desired valley pressure. When the actual delivery pressure reaches the fuel vapor pressure, it cannot decrease further and therefore remains constant at the fuel vapor pressure. The measured delivery pressure also remains constant, as shown, but at a higher value.Because the higher value is greater than the desired valley pressure, the control unit does not increase the voltage applied to the suction pump, and thus the actual delivery pressure remains stuck at the fuel vapor pressure. This can cause the engine to stall. A similar problem can occur if the fuel vapor pressure is higher than the fuel vapor pressure stored in the control unit. For example, if the actual fuel vapor pressure has risen above the desired valley pressure (which can happen due to a rapid increase in fuel temperature), the measured pressure will not decrease to the desired valley pressure, even if the pressure sensor is functioning correctly. Here again, the control unit does not increase the voltage applied to the suction pump because it is waiting for the delivery pressure to decrease to the desired valley pressure, which can cause the engine to stall.

[0062] In dem in Fig. In the exemplary diagram 350 shown in Figure 3E, the pressure sensor is malfunctioning and is measuring values ​​that are too low compared to the actual delivery pressure (represented by waveform 314). In this example, the second exemplary feedback control strategy is being implemented. At the beginning of the curve, the delivery pressure decreases because only a minimal voltage (e.g., slightly above 0) is applied to the LPP, and fuel injection occurs. If the pressure sensor were functioning correctly, it would accurately detect that the actual delivery pressure is reaching the desired valley pressure, and at this point, the controller would increase the voltage applied to the LPP to a higher voltage.However, because the pressure sensor measures values ​​that are too low, the controller does not increase the voltage applied to the LPP (low pressure pump) to a higher voltage when the detected delivery pressure reaches the desired valley pressure. This occurs before the actual delivery pressure has decreased to the desired valley pressure. Consequently, the actual delivery pressure does not reach the desired valley pressure and instead begins to increase in response to the LPP being pulsed to the higher voltage. In the illustrated example, due to the extent to which the pressure sensor measures values ​​that are too low, the actual delivery pressure increases to the set pressure of the pressure relief valve before the detected delivery pressure has increased to the desired peak pressure. Once the actual delivery pressure reaches the set pressure of the pressure relief valve, it cannot increase further and therefore remains constant at the set pressure of the pressure relief valve.The measured delivery pressure also remains constant, as shown, but at a lower value. Since this lower value is lower than the desired peak pressure, the control unit continues to apply the higher voltage to the LPP (low pressure pump), and thus the actual delivery pressure remains stuck at the set pressure of the pressure relief valve. This unfortunately leads to increased fuel consumption and reduced fuel system lifespan, as the delivery pressure is maintained higher than required for the current combustion engine operating conditions.

[0063] In the sensor impairment examples described above, the sensor (e.g., sensor 234 or 235) may be affected. Fig. 2) Values ​​are measured within the instrument's operating range, and the fault is not detected by the previously described methods. In contrast, in accordance with the present disclosure, a flattening of the discharge pressure waveform (e.g., the discharge pressure remaining constant for longer than a threshold duration) can indicate a malfunction of the pressure sensor even when the pressure sensor output is within its normal operating range, as described in more detail herein. Moreover, the detection of such a flattening alone can indicate a malfunction of the pressure sensor, so that the detection of other parameters (e.g., magnitudes of the detected discharge pressure) may not be necessary. Accordingly, the implemented control for pressure sensor diagnostics can advantageously be simplified.

[0064] Now, the focus will shift to... Fig. Reference is made to Figure 4, which shows an exemplary routine 400 for diagnosing a normal-range fault of a pressure sensor located downstream of a fuel suction pump in a fuel system. Instructions for executing routine 400 and the other routines disclosed herein (e.g., routines 500, 510, 530, 600, 700, and 1100) can be provided by a controller (such as the controller 12 from Figure 4). Fig. 1) based on instructions stored in the non-volatile memory of the control unit and in conjunction with sensors of the internal combustion engine, such as those referred to above Fig. The routines described in 1-2 are executed based on the received signals from the sensors. When executing the routines disclosed herein, the control unit can send signals to various actuators of the internal combustion engine to adjust the operation of the internal combustion engine, as described below.

[0065] In module 402, the routine involves performing closed-loop feedback control of voltage pulses applied to the suction pump. This feedback control of the voltage pulses involves the controller receiving feedback from a pressure sensor downstream of the suction pump (e.g., pressure sensor 234 or 235). Fig. 2) receives and adjusts the voltage applied to the suction pump based on the feedback from the pressure sensor (e.g., via an actuator setting on the suction pump). The feedback control can be implemented in accordance with the first or second exemplary feedback control strategy discussed here, or with any other control strategy.

[0066] For error code 404, the routine involves determining whether the entry conditions for diagnosing a within-range pressure sensor fault are met. These conditions might include a pressure sensor output being within a predetermined normal operating range. For example, if the pressure sensor is so malfunctioning that the output is outside the normal operating range (e.g., an out-of-range pressure sensor fault), diagnosing within-range faults is unnecessary. When an out-of-range fault occurs, a corresponding OBD flag may be set on the controller, and thus, determining whether the entry conditions for diagnosing within-range faults are met may involve the controller checking the status of this OBD flag.Furthermore, the entry conditions may include the combustion engine being in steady-state operation and / or the combustion engine temperature (e.g., combustion engine coolant temperature) exceeding a threshold. If the entry conditions are not met, for example, due to an out-of-range sensor fault, the routine terminates. Otherwise, the routine proceeds to 406.

[0067] At step 406, the routine involves measuring the suction pump's delivery pressure using a pressure sensor. This may include continuously measuring the suction pump's delivery pressure throughout the entire operation of the internal combustion engine. After step 406, the routine proceeds to step 408.

[0068] In case 408, the routine involves the control system applying the detected delivery pressure in accordance with the routine. Fig. 7, which is discussed below, for example, is monitored with regard to flattening.

[0069] If a flattening is detected at 410, the routine proceeds to 412 and indicates a pressure sensor fault within the normal range. In one example, indicating a pressure sensor fault within the normal range might involve the controller setting an OBD flag. Furthermore, at 412, the routine switches the fuel pump from a closed-loop control scheme to an open-loop control scheme, in which the pump is powered by a constant non-zero voltage and pressure sensor feedback is ignored. Switching to open-loop pump control allows the fuel system to continue operating even if the pressure sensor is faulty, albeit with lower efficiency than in closed-loop operation when the pressure sensor is not faulty. The routine ends after 412.

[0070] If no flattening is detected at step 410, the routine proceeds to step 414. At step 414, the controller maintains closed-loop control of the suction pump. After step 414, routine 400 ends.

[0071] Now, with reference to Fig. 5A shows an exemplary routine 500 for performing the control of a fuel suction pump with a closed control loop.

[0072] For 502, routine 500 involves measuring or estimating the internal combustion engine operating conditions (e.g., fuel composition, fuel flow rate from the injectors, and current suction pump delivery pressure).

[0073] At 504, the routine involves determining the target pressure and fuel vapor pressure. In one example, the target pressure and fuel vapor pressure can be determined based on the values ​​below, with reference to... Fig. The pressure can be determined dynamically by the controller as described in section 6. In another example, the target pressure can have a predetermined value stored in the controller's non-volatile memory, where the predetermined value is based on properties of the pressure relief valve (e.g., pressure relief valve 211 from [reference missing]). Fig. 2) as well as properties of the fuel system, and the fuel vapor pressure can be calculated depending on the detected fuel temperature and fuel composition.

[0074] For the 506, the routine involves determining the desired peak and trough discharge pressures of the suction pump. The desired peak discharge pressure is the desired maximum discharge pressure of the suction pump, whereas the desired trough discharge pressure is the desired minimum discharge pressure of the suction pump. The desired peak discharge pressure can be a predetermined range below the set pressure; likewise, the desired trough discharge pressure can be a predetermined range above the fuel vapor pressure.

[0075] At 508, the routine involves performing closed-loop control of the suction pump to achieve the desired peak and trough discharge pressure, for example in accordance with the first exemplary feedback control strategy described here (see Fig. 5B), the second exemplary feedback control strategy described here (see Fig. 5C) or the third exemplary feedback control strategy described here (see Fig. 11). The routine ends after 508.

[0076] Fig. Figure 5B shows an example routine 510 for implementing the first example feedback control strategy described here. Routine 510 can be used in conjunction with routine 500 from Fig. 5A, for example, can be performed at 508.

[0077] At 512, the routine involves determining the magnitude of non-zero voltage pulses to be applied to the suction pump and the duty cycle of the pulses that establishes the desired peak and trough delivery pressure determined in routine 500 at 506. For example, the voltage and / or duty cycle can be determined at the controller using a lookup table stored in the controller's non-volatile memory. This table specifies the appropriate voltage and duty cycle based on parameter values ​​such as fuel vapor pressure, set pressure, desired peak and trough delivery pressure of the suction pump, fuel injection rate, DI pump rate, etc. Alternatively, the voltage and / or duty cycle can be determined at the controller using functions that take parameter values ​​(e.g., fuel vapor pressure, set pressure, desired peak and trough delivery pressure, fuel injection rate, DI pump rate, etc.) into account.The program receives input values ​​and outputs the appropriate voltage and / or duty cycle for the pulses. The specified voltage and duty cycle can be selected such that each voltage pulse applied to the suction pump increases the discharge pressure to the desired peak pressure, and such that the next voltage pulse is applied as soon as the discharge pressure decreases from the desired peak pressure to the desired trough pressure. In some examples, the same non-zero effective voltage is always applied during pulsed operation of the suction pump, whereas the duty cycle of the pulses is varied as the internal combustion engine operating conditions change.

[0078] In 514, the routine involves applying voltage pulses to the suction pump, where the pulses have the magnitude and duty cycle determined in 512. For example, the controller can send a signal to an actuator of the suction pump, which in turn applies voltage pulses of the specified magnitude to the working pump with the specified duty cycle.

[0079] In 516, the routine includes monitoring the delivery pressure of the suction pump (e.g., with a pressure sensor such as pressure sensor 234 or 235). Fig. 2) The suction pump's delivery pressure can be monitored over a period of time, such as a period that begins when a voltage pulse is applied and ends when the next voltage pulse is applied. Alternatively, the suction pump's delivery pressure can be monitored continuously throughout the entire operation of the internal combustion engine.

[0080] At step 516, the routine transitions to step 518 to determine whether the measured peak and trough discharge pressures are within a predetermined normal range of the desired peak and trough discharge pressures of the suction pump (e.g., approximately equal to them). Determining whether the measured peak and trough discharge pressures are within the predetermined normal range may involve: calculating a difference between the measured peak discharge pressure and the desired peak discharge pressure at the controller and comparing the absolute value of the difference with a threshold value; and calculating a difference between the measured trough discharge pressure and the desired trough discharge pressure at the controller and comparing the absolute value of the difference with a threshold value.If routine 514 determines that the measured peak and trough delivery pressures are within the predetermined normal range of the desired peak and trough delivery pressures, the routine proceeds to 520 and the controller maintains the current operation (e.g., continues closed-loop control of the fuel suction pump without adjusting the duty cycle / pulse voltage). Following routine 520, routine 500 returns.

[0081] However, if routine 518 determines that the measured peak and trough discharge pressures are not approximately equal to the desired peak and trough discharge pressures, the routine proceeds to step 518. In step 518, the routine involves determining whether the measured peak and trough discharge pressures are greater than the desired peak and trough discharge pressures (e.g., greater by more than a predetermined amount).

[0082] If the detected peak and trough delivery pressures are greater than the desired peak and trough delivery pressures, the routine proceeds to step 524 and the duty cycle of the pulses applied to the suction pump is reduced. For example, the controller may send a signal to a suction pump actuator to reduce the duty cycle of the voltage pulses applied to the suction pump. In some examples, the controller may select the reduction in duty cycle to be proportional to the difference between the detected peak and trough delivery pressures and the desired peak and trough delivery pressures. In this way, the controller can reduce the total amount of voltage applied to the fuel suction pump, thereby reducing the suction pump's delivery pressure. Following step 524, the routine returns to its previous state.

[0083] If, upon returning to step 522, it is determined that the detected peak and trough delivery pressures are lower than the desired peak and trough delivery pressures, the routine proceeds to step 526 and increases the duty cycle of the pulses applied to the suction pump. For example, the controller may send a signal to a suction pump actuator to increase the duty cycle of the voltage pulses applied to the suction pump. In some examples, the controller may select the duty cycle increase to be proportional to the difference between the detected peak and trough delivery pressures and the desired peak and trough delivery pressures. In this way, the controller can increase the total amount of voltage applied to the fuel suction pump, thereby increasing the suction pump's peak and trough delivery pressures. Following step 526, the routine returns to step 526.

[0084] In some examples, routine 500 can be performed iteratively during closed-loop control of the fuel suction pump, allowing the controller to continuously adjust the amount of voltage applied to the fuel suction pump as the desired peak and trough delivery pressures vary.

[0085] Fig. Figure 5C shows an example routine 530 for implementing the second example feedback control strategy described here. Routine 530 can be used in conjunction with routine 500 from Fig. 5A, for example, can be performed at 508.

[0086] In the 532 procedure, the routine involves determining a higher and lower voltage level to be applied to the suction pump during pulsed operation. The higher voltage level can be a predetermined level that rapidly increases the delivery pressure to the desired peak pressure (e.g., 8-12 V), whereas the lower voltage level can be a predetermined level low enough to keep the suction pump powered (e.g., greater than 0 V and less than 0.3 V) without significantly increasing the fuel pressure. When the higher voltage level is applied to the suction pump, it can be considered to be in an ON state, while when the lower voltage level is applied, it can be considered to be in an OFF state, although a minimal amount of voltage is still applied.

[0087] After 532, the routine moves to 534 and the controller applies the predetermined higher voltage to the suction pump.

[0088] After step 534, the routine proceeds to step 536, and the controller determines whether the measured discharge pressure equals the desired peak discharge pressure. If not, the routine continues to monitor the measured discharge pressure until it equals the desired peak discharge pressure. If the pressure sensor malfunctions and measures values ​​that are too low, as described above with reference to... Fig. As discussed in section 3E, this can lead to the measured delivery pressure never reaching the desired peak delivery pressure. In this case, the routine would get stuck at 534, and fuel economy and fuel system longevity would be negatively affected.

[0089] Once the controller determines that the measured discharge pressure equals the desired peak discharge pressure, the routine proceeds to step 538, and the controller determines whether the measured discharge pressure equals the desired trough discharge pressure. If not, the routine continues to monitor the measured discharge pressure until it equals the desired trough discharge pressure. If the pressure sensor malfunctions and measures excessively high values, as described above with reference to... Fig. As discussed in 3D, this can lead to the measured delivery pressure never reaching the desired valley delivery pressure. In this case, the routine would get stuck at 538 and the internal combustion engine could potentially stall due to insufficient fuel pressure.

[0090] It is understood that the execution of routine 530 can be interrupted and / or suspended by the control system in order to switch to a different control strategy for the fuel system or to shut down the internal combustion engine.

[0091] Fig. Figure 6 shows an example routine 600 for determining the setpoint pressure (e.g., the maximum physical pressure in the fuel system for current internal combustion engine operating conditions) and the fuel vapor pressure (e.g., the minimum physical pressure of the fuel system for current internal combustion engine operating conditions). In accordance with routine 600, the controller can initiate a setpoint pressure determination during internal combustion engine operating conditions where the desired peak and trough delivery pressure of the suction pump are relatively high. Furthermore, the controller can initiate a fuel vapor pressure determination when the desired peak and trough delivery pressure of the suction pump are relatively low.In this way, dynamic determination of the target pressure and fuel vapor pressure during combustion engine operation can be carried out intermittently in a manner that takes advantage of fluctuations in the desired peak and trough delivery pressure of the suction pump in order to minimize active adjustments to the combustion engine operation in connection with carrying out the dynamic determination.

[0092] At 602, the routine begins by measuring and / or estimating the internal combustion engine operating conditions, for example in the manner described above for routine 500 at 502.

[0093] Routine 604 involves determining whether the internal combustion engine is operating in steady state and is warmed up. For example, it can be determined that the internal combustion engine is operating in steady state if the engine speed remains substantially constant for at least a threshold duration. Furthermore, it can be determined that the internal combustion engine is warmed up if the engine temperature is found to be greater than a threshold temperature (e.g., based on an output from an internal combustion engine coolant temperature sensor). Routine 600 returns if the internal combustion engine is not warmed up and is not operating in steady state. Otherwise, if the internal combustion engine is warmed up and operating in steady state, the routine proceeds to 606.

[0094] At 606, the routine involves determining whether the entry conditions for determining the target pressure are met. In one example, the entry conditions for determining the target pressure include the peak delivery pressure being greater than a threshold and / or the trough delivery pressure being greater than a threshold. In another example, the entry conditions for determining the target pressure include the internal combustion engine load being greater than a threshold. If 606 determines that the entry conditions for determining the target pressure are not met, the routine proceeds to 608 to determine whether the entry conditions for determining the fuel vapor pressure are met, which is explained in more detail below. Otherwise, if the entry conditions for determining the target pressure at 606 are met, the routine proceeds to 610.

[0095] At 610, the routine involves increasing the duty cycle of voltage pulses applied to the fuel suction pump until the detected pump delivery pressure levels off. This leveling off can be achieved in accordance with routine 700. Fig. 7. This is discussed below. A flattening of the measured delivery pressure indicates that a physical limit of the fuel system has been reached. In this example, the physical limit is the setpoint pressure. The pressure in the fuel system cannot exceed this pressure; when the pressure in the fuel system reaches the setpoint pressure, the pressure relief valve opens and fuel flows back to the fuel tank. The pressure relief valve remains open until the pressure in the fuel system drops to the setpoint pressure, at which point the pressure relief valve closes.

[0096] In the 612 procedure, the routine involves setting the target pressure to the pressure at which flattening occurred. In this way, the control unit determines the maximum possible delivery pressure. Since the fuel pressure sensor can, for example, become clogged or otherwise impaired, this value can change over time. Therefore, it is advantageous for the control unit to periodically recalculate this value. For example, knowing the system's maximum pressure can help the control unit distinguish pressure sensor faults that fall within the normal range, as described below with reference to... Fig. This is described in detail in section 7. Furthermore, knowing the target pressure with high accuracy allows the control system to set the desired peak delivery pressure to be a small margin (e.g., 20 kPa) below the target pressure. In a non-restrictive example, if the target pressure is determined to be 650 kPa, the desired peak delivery pressure can be set to 630 kPa. Consequently, the duty cycle of the voltage pulses applied to the fuel pump to achieve the desired peak delivery pressure can be reduced, thereby improving fuel economy.

[0097] After step 612, the routine transitions to step 614. Step 614 involves returning to normal closed-loop control of the suction pump (e.g., by executing routine 500). Fig. 5A). For example, this may involve the controller determining a duty cycle for the suction pump activation that sets the peak delivery pressure to the desired peak delivery pressure, and controlling a suction pump actuator to adjust the duty cycle of the voltage pulses applied to the suction pump to the determined duty cycle. The adjustment may involve reducing the duty cycle of the suction pump's voltage pulses so that the delivery pressure remains below the set pressure. After 614, the routine proceeds to 608.

[0098] Routine 608 involves determining whether the entry conditions for determining the fuel vapor pressure are met. In one example, the entry conditions for determining the fuel vapor pressure include the peak delivery pressure being lower than a threshold and / or the trough delivery pressure being lower than a threshold. In another example, the entry conditions for determining the fuel vapor pressure include the internal combustion engine load being lower than a threshold. If routine 608 determines that the entry conditions for determining the fuel vapor pressure are not met, routine 600 terminates. Otherwise, if the entry conditions for determining the fuel vapor pressure are met, the routine proceeds to 616.

[0099] In 616, the routine involves reducing the duty cycle of the voltage pulses applied to the fuel suction pump until the pump's delivery pressure flattens out (e.g., according to measurements by pressure sensors 234 or 235). Fig. 2) Flattening can be performed in accordance with routine 700. Fig. 7. This will be determined and discussed below. A flattening of the measured delivery pressure indicates that a physical limit of the fuel system has been reached. In this example, the physical limit is the fuel vapor pressure.

[0100] In routine 618, this involves setting the fuel vapor pressure to the pressure at which flattening occurs, as determined in routine 616. In this way, the control system determines the lowest possible delivery pressure for the fuel system. Fuel temperature can fluctuate during vehicle operation, thus changing the fuel vapor pressure. Determining the fuel vapor pressure in accordance with routine 600 can be more accurate than calculating it based on the detected or inferred fuel composition and temperature. Knowing the fuel vapor pressure at a given time with high accuracy can allow the fuel system to operate at a pressure slightly above the vapor pressure without the risk of losing the desired pressure spread between the vapor pressure and the injection pressure due to temperature fluctuations.For example, this method could be used instead of the compensation method for hot injection devices, metering less fuel than intended, since it operates at a higher pressure (e.g., 50 or 100 kPa) above the fuel vapor pressure. Furthermore, knowing the minimum pressure of the control system can help to distinguish pressure sensor errors that are within the normal range, as described below with reference to [reference missing]. Fig. 7 described in more detail.

[0101] At 620, the routine involves returning to normal closed-loop control of the suction pump (e.g., by executing routine 500). Fig. 5A). For example, this might involve the controller determining a suction pump activation duty cycle that sets the peak delivery pressure to the desired peak delivery pressure, and controlling a suction pump actuator to adjust the duty cycle of the voltage pulses applied to the suction pump to the determined duty cycle. The adjustment might involve increasing the duty cycle of the suction pump voltage pulses so that the delivery pressure remains above the fuel vapor pressure. After 620, the routine returns.

[0102] Fig. Figure 7 shows an example routine 700 for diagnosing a within-normal range fault in fuel pressure sensors. An within-normal range fault can occur when the pressure sensor output is within an expected normal range (e.g., the sensor output voltage is non-zero, and an industry standard check for out-of-normal values ​​does not indicate that the output is out of normal). When an within-normal range fault occurs, the pressure sensor output corresponds to a pressure that is higher or lower than the actual delivery pressure but is still within a normal pressure range of the fuel system.

[0103] In 702, the routine involves determining a threshold duration for which the detected pressure remains constant during proper sensor operation. As above, with reference to Fig. As discussed in 3A-3E, for example, during pulsed operation of the suction pump, the discharge pressure fluctuates in a sawtooth pattern, including sharp peaks and troughs. The threshold duration can be the longest duration for which the pressure is expected to remain at a peak or trough pressure under current operating conditions. The threshold duration can be determined empirically, e.g., during vehicle manufacturing, and stored in non-volatile memory of the controller, e.g., in a lookup table that stores threshold durations corresponding to different operating conditions, such as different pulse widths of the voltage pulses applied to the suction pump. As discussed below with reference to Fig. As discussed in section 9, the threshold duration at a given time can be significantly less than the pulse width of the voltage pulses applied to the suction pump at that time.

[0104] For 704, the routine includes monitoring the detected delivery pressure (e.g., according to measurement by sensor 234 or 235). Fig. 2) In some examples, monitoring can be stopped as soon as the detected discharge pressure remains constant for longer than the threshold duration, even if this occurs before the end of the first voltage pulse applied during monitoring. In other examples, monitoring can be performed during the application of a predetermined number of voltage pulses to the suction pump, regardless of whether the detected discharge pressure remains constant for longer than the threshold duration before all of the predetermined number of voltage pulses have been applied. The predetermined number can be one, two, three, or any other number of voltage pulses.

[0105] In step 706, the routine involves determining whether the measured delivery pressure has remained constant for longer than a threshold duration, such as the threshold duration determined in step 702. In some examples, the fact that the measured delivery pressure remains constant for longer than the threshold duration causes an interruption. In response to a determination that the measured delivery pressure has remained constant for longer than the threshold duration, the routine proceeds to step 708, and the controller indicates a normal error (e.g., by setting an OBD flag). Following step 708, the routine returns.

[0106] If, upon returning to step 706, the measured pressure does not remain constant for longer than a threshold duration during monitoring, the routine proceeds to step 710 and the controller indicates that there is no normal-range pressure sensor fault (e.g., by not setting an OBD flag). Following step 710, the routine returns to the previous step.

[0107] Now, with reference to Fig. 8 shows an exemplary characteristic map 800, which displays relevant signals during the dynamic determination of the target pressure and fuel pressure of a fuel system, e.g., in accordance with routine 600. Fig. Figure 6 illustrates this. Characteristic map 800 represents the target pressure in curve 802, the fuel vapor pressure in curve 804, the desired (e.g., commanded) delivery pressure in curve 806, the voltage applied to the suction pump in curve 808, the measured delivery pressure of the suction pump in curve 810, the internal combustion engine load in curve 812, and the internal combustion engine temperature in curve 814. For all the above curves, the x-axis represents time, with time increasing from left to right along the x-axis.

[0108] The Y-axis of each individual curve corresponds to the specified parameter, with the value increasing from bottom to top. Additionally, line 816 represents a first, higher threshold for the combustion engine load, line 818 represents a second, lower threshold for the combustion engine load, and line 820 represents a threshold for the combustion engine temperature.

[0109] The expected physical behavior of the fuel system is that the set pressure 802 of the pressure relief valve remains constant over its lifetime. In contrast, the fuel vapor pressure 804 depends on the fuel composition and is closely linked to the fuel temperature. Thus, it changes significantly as the vehicle warms up during operation. However, between the fuel composition specification and design measures, the maximum fuel vapor pressure is expected to be limited to a worst-case value. Under normal operating conditions, the desired peak pressure is set to be below the set pressure 802 of the pressure relief valve, and the desired trough pressure is set to be above the fuel vapor pressure 804. However, to determine the values ​​of each, the control system may intentionally disregard this normal target.

[0110] Between t0 and t1, the fuel suction pump can be operated with a closed-loop control scheme, e.g., in accordance with routine 500 from Fig. 5A. The control, such as control 12 from Fig. 1 sends a signal to an actuator of the suction pump, which causes the actuator to apply non-zero voltage pulses to the suction pump with a duty cycle that establishes a desired delivery pressure characteristic 806. As shown, the desired delivery pressure characteristic 806 can vary with the combustion engine load. The voltage pulses applied to the suction pump to achieve the desired delivery pressure characteristic 806 are shown in diagram 808. The delivery pressure of the fuel suction pump, which is determined by a sensor (e.g., pressure sensor 234 or 235) from Fig. 2) is measured and illustrated in curve 810, and increases in response to the application of voltage to the suction pump. Between the energy-supplying pulses, when zero voltage is applied to the suction pump, the delivery pressure of the suction pump decreases due to fuel consumption by the internal combustion engine.

[0111] It can be advantageous to dynamically determine the fuel vapor pressure and set pressure to maximize fuel economy, as described above with reference to Fig. 6 is described in detail. However, to proceed to the dynamic determination of either the fuel vapor pressure or the target pressure, the internal combustion engine must be in steady-state operation and warmed up, and the corresponding initiation conditions must be met. In the example shown in map 800, the internal combustion engine operates in steady state between t0 and t1, and thus the internal combustion engine load 812 remains essentially constant. Furthermore, the internal combustion engine temperature 814 is higher than the threshold value represented by the dashed line 820, indicating that the internal combustion engine is warmed up. In addition, the internal combustion engine load is above the first, higher threshold value 816. Therefore, at t1, the initiation conditions for determining the target pressure are met. In other examples, however, additional initiation conditions may have to be met before the target pressure is determined.

[0112] Between t1 and t2 of the characteristic curve 800, the control unit determines the target pressure 802, which is the maximum delivery pressure possible due to the presence of the pressure relief valve in the fuel system. To determine the maximum delivery pressure, the control unit increases the duty cycle of the voltage pulses 808 applied to the fuel suction pump at t1, as shown. This increase does not occur in response to a change in combustion engine operating conditions (e.g., an increase in combustion engine load) or an increase in the desired (e.g., requested or commanded) delivery pressure; instead, the increase is performed solely for the purpose of determining the maximum delivery pressure of the fuel system, which corresponds to the target pressure of the pressure relief valve.Although, for example, the combustion engine load 812 remains essentially constant between time t0 and t1, the control system nevertheless increases the duty cycle of the voltage pulses applied to the fuel suction pump in order to perform the dynamic determination of the target pressure.

[0113] When the measured delivery pressure 810 reaches the target pressure 802, the waveform of the measured delivery pressure develops a flattened peak characteristic. In the example shown, the delivery pressure reaches the target pressure during the application of the first voltage pulse, which has an increased pulse width. In other examples, however, the increase in the duty cycle can be performed incrementally, so that the measured delivery pressure only reaches the target pressure after several voltage pulses have been applied. This advantageously reduces the steepness of the pressure increase supplied to the fuel injection devices. Furthermore, incremental increase in the duty cycle provides the detection of flattened peaks while minimizing the increase in delivery pressure, so that the delivery pressure remains closer to the optimal delivery pressure under current internal combustion engine operating conditions.

[0114] In the 800 characteristic curve, the target pressure is 650 kPa, and the waveform of the measured delivery pressure flattens out at 650 kPa for a non-trivial duration (remaining constant). This specific target pressure is merely an example; the target pressure varies depending on the characteristics of the pressure relief valve and fuel system.

[0115] In the example shown, the controller continues to monitor the measured delivery pressure after flattening has been detected; specifically, another voltage pulse is applied after a flattening event is detected, so that the delivery pressure signal flattens twice at its peak. Applying one or more additional voltage pulses with an increased pulse width relative to the nominal pulse width, even after the initial flattening event has been detected, can be advantageous because it can reduce false-positive flattening detections (e.g., if an anomaly occurs that leads to a temporary flattening of the measured delivery pressure signal, which does not represent the actual target pressure).In other examples, however, the controller can terminate the setpoint determination process as soon as flattening is detected and update the stored setpoint to the pressure at which flattening occurred. This can limit the time the controller increases the voltage applied to the suction pump to perform the determination, and therefore improve fuel economy.

[0116] After detecting the flattening of the waveform of the measured delivery pressure, the controller compares the pressure at which the measured delivery pressure flattened with a previously determined target pressure stored in non-volatile memory. Since the target pressure is subject to changes over time (e.g., if the pressure relief valve becomes clogged or if other parameters of the fuel system change), it may be desirable to periodically recalculate the target pressure; for this purpose, routine 600 can be executed intermittently or, optionally, continuously during pulsed operation of the suction pump. In other examples, routine 600 can be executed only when pulsed operation of the suction pump is initiated.

[0117] At t2, the control system ends the process for determining the target pressure and switches the operation of the suction pump back to the state set in routine 500. Fig. 5A describes a closed-loop control scheme. For example, the controller can, as shown, reduce the duty cycle of the voltage pulses 808 applied to the suction pump to a value that reflects current combustion engine operating parameters (e.g., the same value that is applied from time t0 to t1).

[0118] Between t2 and t3, the combustion engine load 812 decreases to a level lower than the second threshold 818. This decrease in the combustion engine load can occur due to a change in the combustion engine operation (e.g., a transition to idling or the vehicle coasting downhill). Furthermore, the combustion engine temperature 814 is higher than the threshold represented by the dashed line 820, indicating that the combustion engine is warmed up. Therefore, at t3, the entry conditions for determining the fuel vapor pressure are met. However, in other examples, additional entry conditions may be required before the fuel vapor pressure can be determined. Since the fuel vapor pressure depends on the fuel temperature in the fuel system, the entry conditions might include, for example, that the fuel temperature remains substantially constant for at least one threshold duration.

[0119] After determining that the entry conditions are met at t3, the control system modifies the operation of the suction pump to determine the fuel vapor pressure by reducing the duty cycle of the voltage pulses 808 applied to the fuel suction pump. This reduction does not occur in response to a change in internal combustion engine operating conditions (e.g., a decrease in the internal combustion engine load) or a decrease in the desired (e.g., requested or commanded) delivery pressure; instead, the reduction is performed solely for the purpose of determining the maximum fuel system delivery pressure, which corresponds to the set pressure of the pressure relief valve. For example, although the internal combustion engine load 812 remains substantially constant from the period immediately before t3 until t3, the control system nevertheless reduces the duty cycle of the voltage pulses applied to the suction pump at t3 to perform the dynamic determination of the fuel vapor pressure.

[0120] When the delivery pressure 810 reaches the fuel vapor pressure 804, the waveform of the detected delivery pressure develops a flattened valley characteristic. In the illustrated example, the delivery pressure reaches the fuel vapor pressure after the application of the first voltage pulse, which has a reduced pulse width, and before the application of a second voltage pulse, which also has a reduced pulse width. In other examples, however, the reduction of the duty cycle can be performed incrementally, so that the detected delivery pressure only reaches the fuel vapor pressure after several voltage pulses have been applied, which advantageously reduces the steepness of the pressure decrease supplied to the fuel injection devices.Furthermore, incrementally reducing the duty cycle provides the detection of flattened valleys while minimizing the decrease in delivery pressure, so that the delivery pressure remains closer to the optimal delivery pressure under current internal combustion engine operating conditions.

[0121] In the 800 characteristic curve, the fuel vapor pressure is 300 kPa, and the waveform of the measured delivery pressure flattens out at 300 kPa for a non-trivial period (remaining constant). This specific fuel vapor pressure is merely an example; the fuel vapor pressure varies depending on the operating conditions of the fuel system (e.g., fuel temperature). Therefore, it can be advantageous to periodically remeasure the fuel vapor pressure.

[0122] In the example shown, the controller continues to monitor the detected delivery pressure after flattening has been detected; specifically, another voltage pulse is applied after a flattening event has been detected, so that the delivery pressure signal flattens twice at the trough. As discussed above with reference to determining the target pressure, applying one or more additional voltage pulses with a reduced pulse width relative to the nominal pulse width, even after the initial flattening event has been detected, can be advantageous in that it can reduce false-positive flattening detections (e.g., if an anomaly occurs that leads to a temporary flattening of the detected delivery pressure signal, which does not reflect the actual fuel vapor pressure).In other examples, however, the control system can terminate the fuel vapor pressure determination process as soon as a flattening is detected and update the stored fuel vapor pressure to the pressure at which the flattening occurred. This can limit the time the delivery pressure is modified from the requested delivery pressure to perform the determination and thus improve internal combustion engine operation.

[0123] After detecting the flattening of the waveform of the measured delivery pressure, the controller stores the pressure at which the measured delivery pressure flattened as fuel vapor pressure in non-volatile memory. Routine 600 can be executed intermittently or, optionally, continuously during pulsed operation of the suction pump to improve the accuracy of the closed-loop control. In other examples, Routine 600 can be executed only when pulsed operation of the suction pump is initiated.

[0124] After determining the fuel vapor pressure, the control unit switches the operation of the suction pump back to the setting in routine 500. Fig. 5A describes a closed-loop control scheme. For example, the controller can adjust the duty cycle of the voltage pulses 808 applied to the suction pump to a value that reflects current combustion engine operating parameters (e.g., the current characteristic of the desired delivery pressure of the suction pump, which is represented by the curve 806).

[0125] While map 800 illustrates the dynamic determination of the target pressure, which is followed shortly thereafter by the dynamic determination of the fuel vapor pressure, this sequence of events is merely exemplary. The dynamic determination of the target pressure can be performed at any time when the corresponding initiation conditions (including an internal combustion engine load above the first, higher threshold) are met, and likewise, the dynamic determination of the fuel vapor pressure can be performed at any time when the corresponding initiation conditions (including an internal combustion engine load below the second, lower threshold) are met.

[0126] In examples where the vehicle containing the fuel system is a hybrid vehicle, the internal combustion engine load can be increased or decreased to determine the target pressure or fuel vapor pressure, even if the engine load is outside the appropriate normal range (e.g., above the first, higher threshold or below the second, lower threshold), by adding or subtracting a certain amount of load from the engine via the electric machine and the battery. Instead of waiting until the engine load exceeds the first, higher threshold to determine the target pressure, the engine load can, for example, be increased beyond the first, higher threshold, and the excess engine power can be converted into electrical energy via the electric machine (operating in generator mode) and stored in the energy storage device.Conversely, instead of waiting until the combustion engine load falls below the second, lower threshold to determine the fuel vapor pressure, the combustion engine load can be reduced below the second, lower threshold, and the battery and electric machine (operating in an electric motor mode) can provide supplementary torque to the vehicle wheels, so that the requested torque is still provided to the vehicle wheels despite the decrease in the combustion engine load.

[0127] Furthermore, in examples where the vehicle containing the fuel system is a hybrid vehicle and the robust feedback control strategy is implemented, the volume of fuel consumed by the combustion engine can be monitored while the suction pump is switched off. If the volume of fuel consumed by the combustion engine while the suction pump is switched off reaches a predetermined volume before the pressure sensor output signal has decreased to a desired valley pressure, the suction pump can be switched on, the pressure sensor output signal can be stored as the first stored value, and a dynamic determination of the fuel vapor pressure of the fuel system can be requested.If the volume of fuel drawn by the internal combustion engine while the suction pump is switched off exceeds an expected amount for the current operating conditions, as discussed above, but the desired valley pressure has not yet been reached, this indicates that either the sensor is measuring inaccurately or the fuel vapor pressure has changed (e.g., risen above the desired valley pressure). To determine which of these problems is present, the control unit can dynamically determine the fuel vapor pressure by reducing the fuel rail pressure until it cannot be reduced further. To perform this without compromising the desired internal combustion engine operation during conditions where the requested internal combustion engine output torque is above a threshold, the electric motor / generator can be used to supplement the internal combustion engine output torque.If a requested vehicle wheel torque exceeds a first threshold, the control unit can send signals to actuators to mechanically couple a crankshaft of the internal combustion engine to the electric motor / generator and reduce the internal combustion engine load until the pressure sensor output signal remains constant for at least a first threshold duration, while electrical energy is converted into torque by the electric motor / generator and the torque is delivered to the vehicle wheels. The pressure at which the output signal remains constant can then be stored as an updated fuel vapor pressure, and if the updated fuel vapor pressure is lower than the first stored value, the control unit can indicate that the pressure sensor is measuring values ​​that are too high.In this case, the sensor output can then be calibrated, taking into account the difference between the updated fuel vapor pressure and the first stored value. Alternatively, the controller can indicate that the pressure sensor is measuring correct values ​​and is not affected, and subsequently perform feedback control of the suction pump based on the updated fuel vapor pressure.

[0128] Similarly, during pulsed operation of the suction pump, its operating time can be monitored. If the pump's operating time reaches a calibrated maximum before the pressure sensor output signal has increased to a desired peak pressure, the pump can be switched off, the pressure sensor output signal value can be stored as a second stored value, and a dynamic determination of the pressure relief valve setpoint pressure can be requested. If the suction pump remains switched on for a calibrated maximum operating time as described above, but the desired peak pressure has not yet been reached, this indicates that either the sensor is measuring inaccurately or the pressure relief valve setpoint pressure has changed (e.g., decreased from the stored value).To determine which of these problems exists, the control system can dynamically determine the target pressure by increasing the fuel rail pressure until it can no longer be increased. To perform this without compromising the desired combustion engine operation during conditions where the requested combustion engine output torque is below a threshold, the electric motor / generator can be used to absorb excess combustion engine output torque.If a requested vehicle wheel torque falls below a second threshold, the control unit can send signals to actuators to mechanically couple the crankshaft to the electric motor / generator, increase the combustion engine load until the pressure sensor output signal remains constant for at least a second threshold duration, while a portion of the combustion engine's output torque is converted into electrical energy by the electric motor / generator and stored in the battery, and store the pressure at which the output signal remains constant as the updated target pressure. If the updated target pressure is greater than the second stored value, the control unit can indicate that the pressure sensor is measuring values ​​that are too low.In this case, the sensor output can then be calibrated, taking into account the difference between the updated setpoint pressure and the second stored value. Alternatively, the controller can indicate that the pressure sensor is measuring correct values ​​and is not malfunctioning, and subsequently perform feedback control of the suction pump based on the updated setpoint pressure.

[0129] Fig. Figure 9 shows an exemplary characteristic map 900, which contains relevant signals for diagnosing a fault within the normal range of a pressure sensor that detects the delivery pressure of a suction pump, e.g. in accordance with routine 700. Fig. Figure 7 illustrates this. Characteristic curve 900 shows the commanded delivery pressure of the suction pump in curve 902, the voltage applied to the suction pump in curve 904, the measured delivery pressure in curve 906, an indication of whether inlet conditions have been met in curve 912, and an indication of an error within the normal range in curve 916. Additionally, the target pressure is symbolically represented by the dashed line 908, and the fuel vapor pressure is symbolically represented by the dashed line 910. For all of the above, the x-axis represents time, with time increasing from left to right along the x-axis. The y-axis of curves 902, 904, and 906 corresponds to the specified parameter, with the value increasing from bottom to top.

[0130] From t0 to t1, the control system performs closed-loop regulation of voltage pulses applied to the suction pump (e.g., in accordance with the first or second exemplary feedback control strategy described here). As shown in curve 904, the applied voltage pulses have a pulse width of 905. The pulsed operation generates a sawtooth waveform for the detected delivery pressure, as shown in curve 906. Before t1, the conditions for diagnosing a pressure sensor fault within the normal range are not met. For example, the combustion engine temperature is below a threshold, the combustion engine is not operating in steady state, and / or other conditions are not met. Furthermore, a pressure sensor fault within the normal range is not indicated during this period (e.g.,No OBD flag is set, indicating a pressure sensor error within the normal range.

[0131] At time t1, the control system indicates, as shown in curve 912, that the entry conditions for diagnosing a pressure sensor fault within the normal range have been met (e.g., in response to measured and / or derived signals for values ​​of combustion engine load, combustion engine temperature, etc.). In response to this information, the control system initiates a routine for diagnosing a pressure sensor fault within the normal range, such as routine 700 from [reference missing]. Fig. 7. This may involve first determining a threshold duration for which the detected delivery pressure remains constant during proper sensor operation. An example threshold duration of 918 is shown in map 900. The threshold value can optionally be determined at the controller as a function of the pulse width, e.g., as a fraction of the pulse width. For example, the controller can logically determine an appropriate threshold duration for current operating conditions of the internal combustion engine and fuel system based on logic rules as a function of the pulse width. In the example shown, the threshold duration of 918 is less than the pulse width of 905. It is understood that the threshold duration can be significantly smaller than the pulse width (e.g., less than 1 / 100 of the pulse width) without deviating from the scope of this disclosure.

[0132] From t1 to t2, the controller performs the diagnostic routine by monitoring the measured delivery pressure to determine whether it remains constant for longer than the threshold duration (e.g., flattens out). As shown in curve 906, the sensor operates within the normal range with the expected sawtooth output until shortly before t2. However, shortly before t2, a sensor error within the normal range begins to occur; at t2, the measured delivery pressure has remained constant for the threshold duration. In this example, the flattening occurs at the trough of the waveform, indicating that the pressure sensor is measuring values ​​that are too high. However, when performing the diagnostics, the controller can ignore the pressure magnitude at which the flattening occurs and thus cannot distinguish between the flattening at the trough and the peak (e.g., the diagnostics are performed regardless of the pressure magnitude at which the measured signal remains constant).Such an operation can advantageously simplify the control strategy.

[0133] After detecting at t2 that the measured delivery pressure has remained constant for the threshold duration, the controller indicates a pressure sensor error within the normal range, as shown in curve 916. Furthermore, at t2, the controller switches from closed-loop control of the suction pump, where voltage pulses are applied to the pump, to open-loop control of the suction pump, where a constant non-zero voltage is applied. As shown, for example, in curve 904, a constant non-zero voltage is applied to the suction pump starting at t2. In response to the application of the constant non-zero voltage, the measured delivery pressure increases to a pressure higher than the average pressure of the sawtooth waveform and then remains essentially constant at this pressure (assuming a constant fuel injection rate).However, the delivery pressure can vary in response to variations in the fuel injection rate that occur during open-loop fuel pump operation. By switching to open-loop control of the suction pump when a pressure sensor error within the normal range is detected, the control system no longer relies on the imprecise feedback from the pressure sensor. This, in turn, improves the robustness of the suction pump control and reduces the likelihood of an inappropriate amount of fuel being supplied to the internal combustion engine cylinders.

[0134] In the example shown in map 900, a pressure sensor error within the normal range is indicated as soon as the measured delivery pressure has remained constant for the threshold duration. In other examples, such as the one in map 1000 from Fig. In example 10, the control system can further monitor the detected delivery pressure during the application of multiple voltage pulses to ensure that the detected flattening is not accidental.

[0135] Now, with reference to Fig. 10 another exemplary characteristic map 1000 is shown, which contains relevant signals for diagnosing a fault within the normal range of a pressure sensor that detects the delivery pressure of a suction pump, e.g. in accordance with routine 700 from Fig. Figure 7 illustrates this. Characteristic map 1000 shows the commanded delivery pressure of the suction pump in curve 1002, the voltage applied to the suction pump in curve 1004, the measured delivery pressure in curve 1006, an indication of whether inlet conditions have been met in curve 1012, and an indication of an error within the normal range in curve 1016. Additionally, the target pressure is symbolically represented by the dashed line 1008, and the fuel vapor pressure symbolically by the dashed line 1010. For all of the above, the x-axis represents time, with time increasing from left to right along the x-axis. The y-axis of curves 1002, 1004, and 1006 corresponds to the specified parameter, with the value increasing from bottom to top.

[0136] From t0 to t1, the controller performs closed-loop control of voltage pulses applied to the suction pump, as described above with reference to characteristic curve 900. However, while the closed-loop control shown in characteristic curve 900 is performed in accordance with either the first or second exemplary feedback control strategy, the closed-loop control shown in characteristic curve 1000, for example, is not compatible with the second exemplary feedback control strategy (since the controller does not "stuck" if the desired peak pressure is not reached due to flattening). In other examples, however, an error within the normal range can be detected if peak flattening occurs during closed-loop control of the suction pump in accordance with the second exemplary feedback control strategy.

[0137] Before t1, the conditions for diagnosing a pressure sensor error within the normal range are not met, and no error within the normal range is reported. However, as shown in graph 1006, an error within the normal range does occur, as evidenced by the flattening of the peaks in the detected pressure signal.

[0138] At time t1, the controller indicates, as shown in curve 912, that the entry conditions for diagnosing a pressure sensor error within the normal range have been met, and initiates a routine for diagnosing an error within the normal range, such as routine 700 from Fig. 7. As discussed above with reference to characteristic map 900, this may involve first determining a threshold duration for which the detected delivery pressure remains constant during proper sensor operation; an exemplary threshold duration is shown at 1018. In the example shown, the threshold duration 1018 is smaller than the pulse width 1005 of the voltage pulses applied to the suction pump.

[0139] From t1 to t2, the controller executes the diagnostic routine by monitoring the measured delivery pressure to determine whether it remains constant for longer than the threshold duration (e.g., flattens out). As stated above, a fault within the normal range occurs at the time the diagnostic routine is initiated; after the application of the first voltage pulse, which is applied during the diagnostic routine, the measured delivery pressure rises and then flattens out, remaining constant for longer than the threshold duration of 1018. While the controller indicates a fault within the normal range as soon as flattening for the threshold duration is detected in the exemplary diagnostic routine shown in map 900, map 1000 shows an exemplary diagnostic routine in which the controller waits until several individual instances of flattening have been detected before indicating a fault within the normal range.Specifically, in the example shown, the controller only indicates a within-the-normal range error when the measured delivery pressure remains constant for the threshold duration for the third time, which occurs at t2. This example is not restrictive; in other examples, the controller may wait to indicate a within-the-normal range error until flattening has occurred one, two, three, four, five, or more times. Alternatively, the controller may perform another routine to detect flattening of the measured pressure signal without deviating from the scope of this disclosure.

[0140] After specifying the error within the normal range, as shown in characteristic curve 900, the control system switches from closed-loop to open-loop control of the suction pump. As shown, for example, in curve 1004, a non-zero continuous voltage is applied to the suction pump after t2. As shown, the continuous voltage is only applied once the detected discharge pressure has decreased by a certain amount from the flattened peak pressure; such operation may be appropriate because the desired discharge pressure during pulsed operation of the suction pump may be lower than the peak pressure. In other examples, however, the continuous voltage may be applied as soon as the error within the normal range is detected, or the voltage may be increased to the continuous voltage, or another strategy may be used to transition from pulsed to continuous operation of the suction pump.In any case, the measured delivery pressure increases in response to the application of a non-zero continuous voltage to a pressure higher than the average pressure of the sawtooth waveform and then remains essentially constant at this pressure (assuming a constant fuel injection rate). However, the delivery pressure can vary in response to variations in the fuel injection rate that occur during open-loop operation of the fuel pump.

[0141] Routine 700 and characteristic curves 900 and 1000 are part of a diagnostic procedure for a pressure sensor fault within the normal range and the corresponding adjustment of the suction pump control from closed-loop to open-loop control. Alternatively, instead of switching to open-loop control of the suction pump when a pressure sensor fault within the normal range occurs, an exemplary feedback control strategy, referred to here as robust control, can be used.

[0142] Fig. Figure 11 shows an exemplary routine 1100 for performing robust control of a fuel suction pump in accordance with the third exemplary feedback control strategy. This robust control strategy can advantageously allow closed-loop feedback control of the suction pump to continue even in the event of a malfunction of the pressure sensor or an increase in fuel vapor pressure that has not been detected by the controller, while minimizing stalling and excessive fuel consumption. Routine 1100 can be used in conjunction with routine 500 from Fig. 5A, for example, can be performed at 508.

[0143] In routine 1102, this involves switching on the suction pump. As discussed above in relation to routine 530, this might include, for example, the controller setting an actuator of the suction pump to apply a predetermined higher voltage level to the suction pump, which quickly increases the delivery pressure to the desired peak pressure (e.g., 8-12 V) determined in routine 500.

[0144] After step 1102, the routine proceeds to step 1104, where the controller determines whether the measured delivery pressure is lower than the desired peak delivery pressure. For example, the controller can receive a signal from a pressure sensor indicating the delivery pressure and compare this measured pressure with the stored value of the previously determined desired peak delivery pressure. If the response at step 1104 is "yes," indicating that either the delivery pressure has not yet reached the desired peak pressure or the sensor output is inaccurate, the routine proceeds to step 1106.

[0145] At 1106, the controller determines whether the duration for which the suction pump has been switched ON is less than a calibrated maximum value. The calibrated maximum value can be a predetermined value stored in memory or, alternatively, determined by the controller during the execution of routine 1100, depending on various internal combustion engine operating parameters (e.g., fuel consumption rate, internal combustion engine speed, voltage level applied to the suction pump, etc.). The calibrated maximum value represents the maximum duration for which the suction pump should remain switched ON during conditions where a malfunction of the pressure sensor or another fault prevents the detected delivery pressure from reaching the desired peak pressure. If the answer at 1106 is YES, the routine returns to 1104.If, otherwise, the answer at 1106 is NO, indicating that the suction pump has already been switched ON for at least the calibrated maximum duration, the routine returns to 1102, or optionally proceeds to 1108.

[0146] At 1108, the controller calibrates the pressure sensor output to generate a more accurate reading of the actual delivery pressure. If the suction pump remains switched on for at least the calibrated maximum duration, this can occur due to a flattening of the sensor signal, reflecting the fact that the actual delivery pressure equals the set pressure of the pressure relief valve. Such a flattening can occur, for example, in accordance with the procedure from Fig. 7. In an exemplary calibration strategy, after determining that the suction pump has remained switched ON for the calibrated maximum duration, the controller proceeds to determine whether the detected discharge pressure has remained constant for longer than a threshold duration (e.g., has leveled off). If so, the controller then determines a pressure offset as the difference between the setpoint pressure of the pressure relief valve and the pressure at which the detected discharge pressure leveled off, and calibrates the output of the pressure sensor by adding the offset to the detected discharge pressure. Thus, the calibrated discharge pressure generated at the controller at a given time can be equal to the sum of the offset and the currently detected discharge pressure.The calibrated delivery pressure can then replace the measured delivery pressure in the feedback control performed by the controller, which can advantageously improve the accuracy of the suction pump control and thus improve fuel economy. This exemplary calibration strategy is described in [reference to relevant document]. Fig. Figure 12B, which is discussed below, is appropriate if the pressure sensor consistently measures values ​​that are too low. However, other methods for calibrating the detected conveying pressure may be used without deviating from the scope of this disclosure.

[0147] After 1108, the routine proceeds to 1110. If the response at 1104 is NO, indicating that the measured delivery pressure has reached the desired peak delivery pressure, the routine proceeds to 1110. At 1110, the routine involves switching off the suction pump. As discussed above with reference to routine 530, this might involve, for example, the controller setting a suction pump actuator to apply a predetermined lower voltage level to the suction pump, low enough to keep the suction pump powered (e.g., greater than 0 V and less than 0.3 V) and not significantly increasing the fuel pressure. In other examples, however, switching off the suction pump might involve the controller setting a suction pump actuator to apply 0 V to the suction pump. The predetermined lower voltage level could be determined, for example, by executing routine 500.By switching off the suction pump when its ON duration reaches the calibrated maximum duration, regardless of whether the measured discharge pressure has reached the peak discharge pressure, the pulsed operation of the suction pump can continue even if the pressure sensor is faulty. For example, if the sensor is faulty and measures values ​​that are too low, the measured discharge pressure may remain unchanged at a level below the desired peak pressure when normal closed-loop control of the suction pump (e.g., the routine from...) is used. Fig. 5C) is performed because the control strategy can only switch off the suction pump once the desired peak pressure has been reached. In contrast, the robust control strategy of routine 1100 "resets" the suction pump control when the suction pump has reached the calibrated maximum on-time, regardless of whether the discharge pressure has reached the desired peak discharge pressure.

[0148] After 1110, the routine proceeds to 1112, and the controller determines a desired pressure drop ΔP between the peak and valley pressures, as well as a system stiffness S. The desired pressure drop ΔP represents the desired degree to which the delivery pressure decreases during the period that begins when the suction pump is switched OFF and ends when the suction pump is switched ON again, and can, for example, be equal to the difference between the desired peak and valley pressures. The system stiffness S can represent the compression modulus of the fluid within the fuel system (e.g., fuel or fuel and air). The compression modulus can depend on the density of the fluid within the fuel system and can be determined by the Equation = ρdPdρ The equation is represented by the equation where ρ is the density of the fluid in the fuel system and P is the pressure in the fuel system (e.g., the delivery pressure). The value of S can be obtained from the controller using a lookup table stored in memory on the controller, or alternatively, it can be calculated on the controller based on currently acquired parameter values, such as the acquired delivery pressure, and known dimensions of the fuel system (e.g., the volume of a fuel channel within the fuel system), which are also stored in memory on the controller. Since the equation relies on the rate of change of the acquired delivery pressure rather than the magnitude of the acquired delivery pressure, it is remarkably possible to accurately determine S even if the pressure sensor output is misaligned due to interference.

[0149] After step 1112, the routine transitions to step 1114, and the controller determines a volume V of fuel to be drawn in by the combustion engine while the suction pump is switched off. This should trigger a transition of the suction pump's state from OFF to ON. V can be determined at the controller as a function of ΔP and S, for example, in a non-restrictive example, via the Equation = ΔPS. The specified volume V represents the volume of fuel that, when drawn in by the internal combustion engine (e.g., via fuel injection), should reduce the delivery pressure from the desired peak pressure to the desired valley pressure, given the current stiffness S of the fuel system, starting from the point when the delivery pressure reaches the desired peak pressure. If the volume V of fuel has been drawn in by the internal combustion engine since the suction pump was switched off, with the delivery pressure at the desired peak pressure, and the measured delivery pressure is still higher than the desired valley pressure, this may indicate that the pressure sensor is malfunctioning (e.g., measuring values ​​that are too high) or that the fuel vapor pressure is higher than the value stored in the control unit.

[0150] After 1114, the routine proceeds to 1116, and the controller determines whether the detected discharge pressure is greater than the desired valley discharge pressure. If the answer at 1116 is NO, indicating that the detected discharge pressure has reached the desired valley pressure, the routine returns to 1102 to switch on the suction pump, and another voltage pulse is applied to the suction pump. It is understood, however, that routine 1100 can be interrupted at any time (e.g., via a system interruption) to terminate the robust feedback control of the suction pump.

[0151] If the answer to 1116 is otherwise YES, the routine proceeds to 1118 and the controller determines whether the volume of fuel consumed by the internal combustion engine since the suction pump was switched off is greater than the volume V determined in 1114. The volume of fuel consumed by the internal combustion engine since the suction pump was switched off can be equal to the amount of fuel injected into the internal combustion engine by the fuel system during the period beginning when the suction pump was switched off and ending after the execution of 1118, and can be determined by the controller based on measured values ​​and / or stored data regarding the control of the fuel injection devices during the relevant period.

[0152] If the answer at 1118 is NO, the routine returns to 1116. If the answer at 1118 is otherwise YES, the routine returns to 1102 or optionally proceeds to 1120 before returning to 1102.

[0153] At 1120, the control unit calibrates the output of the pressure sensor that measures the delivery pressure to generate a more accurate reading of the actual delivery pressure. If the volume of fuel consumed by the combustion engine since the suction pump was switched off is greater than the volume V, this can occur due to a flattening of the signal from the sensor, which reflects the fact that the actual delivery pressure equals the fuel vapor pressure. Such a flattening can occur, for example, in accordance with the procedure from Fig. 7. In an exemplary calibration strategy, after determining that the volume of fuel consumed by the combustion engine since the suction pump was switched off is greater than the volume V, the control unit proceeds to determine whether the detected delivery pressure has remained constant for longer than a threshold duration (e.g., has leveled off). If so, the control unit then determines a pressure offset as the difference between the pressure at which the detected delivery pressure leveled off and the fuel vapor pressure, and calibrates the pressure sensor output by subtracting the offset from the detected delivery pressure. Thus, the calibrated delivery pressure generated at the control unit at a given time can be equal to the currently detected delivery pressure minus the offset.The calibrated delivery pressure can then replace the measured delivery pressure in the feedback control performed by the controller, which can advantageously improve internal combustion engine operation by reducing the probability of stalling due to low fuel rail pressure. This exemplary calibration strategy is described in [reference to relevant document]. Fig. Figure 12D illustrates the discussion below and is appropriate if the pressure sensor consistently measures excessively high values.

[0154] After 1120, the routine returns to 1102 or optionally terminates if the controller ends the robust feedback control of the suction pump, for example, due to the combustion engine being switched off. By returning to 1102 and switching on the suction pump when the volume of fuel consumed by the combustion engine reaches a predetermined level, regardless of whether the detected delivery pressure has decreased to the desired valley delivery pressure, the pulsed operation of the suction pump can continue even if the pressure sensor is faulty. For example, if the sensor is faulty and measures values ​​that are too high, the detected delivery pressure can remain unchanged at a level above the desired valley pressure when normal closed-loop control of the suction pump (e.g., the routine from Fig. 5C) is carried out because the control strategy can only switch on the suction pump once the desired valley pressure has been reached. In contrast, the robust control strategy of routine 1100 "resets" the suction pump control when a certain amount of fuel has been consumed by the internal combustion engine, regardless of whether the delivery pressure has reached the desired peak delivery pressure. Such control can advantageously reduce engine stalling due to insufficient fuel delivery pressure.

[0155] It is understood that if calibration of the measured delivery pressure is initiated during the execution of routine 1100 during a given operating period, the calibrated delivery pressure can replace the measured delivery pressure in subsequent iterations of routine 1100 during that same operating period. Depending on the accuracy of the calibrated delivery pressure, further calibration may not be necessary during subsequent executions of routine 1100. Alternatively, if the impairment of the pressure sensor worsens, further calibration can be performed.

[0156] Fig. Figures 12A-12D show exemplary characteristic maps that display relevant signals during the control of the suction pump in accordance with the third exemplary feedback control strategy, e.g., in accordance with routine 1100. Fig. Figure 11 illustrates this. For the sake of simplicity, the characteristic curves shown assume that the combustion engine operates in a steady state, fuel is drawn in by the combustion engine at a constant rate, and the magnitude of each voltage pulse applied to the suction pump is the same.

[0157] First, the focus will be on Fig. Reference is made to Figure 12A, which shows an exemplary characteristic curve 1200, representing the voltage applied to the suction pump in curve 1202, the actual delivery pressure of the suction pump in curve 1204, and the measured delivery pressure of the suction pump in curve 1206. For all these curves, the X-axis represents time, with time increasing from left to right along the X-axis. The Y-axis of each individual curve corresponds to the specified parameter, with the value increasing from bottom to top. Additionally, line 1208 represents the (actual) target pressure of the pressure relief valve, line 1210 represents the desired peak delivery pressure, line 1212 represents the desired trough delivery pressure, and line 1214 represents the (actual) fuel vapor pressure.

[0158] Shortly after t0, the measured discharge pressure reaches the desired valley discharge pressure 1212; in response, the controller switches on the suction pump (e.g., by sending a signal to an actuator of the suction pump). However, the pressure sensor measuring the discharge pressure is registering values ​​that are too low; the measured discharge pressure is initially lower than the actual discharge pressure. Accordingly, the suction pump is switched on when the actual discharge pressure is higher than the desired valley discharge pressure. Here, the initial difference happens to be smaller than the difference between the setpoint pressure of the pressure relief valve and the desired peak pressure. Therefore, when the measured discharge pressure reaches the desired peak pressure, the actual discharge pressure has not yet reached the setpoint pressure of the pressure relief valve. Upon recognizing that the measured discharge pressure has reached the desired peak pressure, the controller switches off the suction pump.Before it was switched off, the suction pump was switched on for a time of 1216, which is shorter than a calibrated maximum on time of 1218 for the suction pump. After the suction pump is switched off, the actual delivery pressure decreases at a rate corresponding to the rate at which fuel is drawn from the fuel system by the internal combustion engine.

[0159] At t1, the pressure sensor is further impaired and begins to measure even lower values, so the detected discharge pressure is a second order lower than the actual discharge pressure, with the second order being larger than the first. This second order happens to be larger than the difference between the set pressure of the pressure relief valve and the desired peak pressure. At t2, the detected discharge pressure increases to the desired valley pressure before the actual discharge pressure has decreased to the desired valley pressure (because the pressure sensor is measuring values ​​that are too low). Here, the controller switches the suction pump back on at t2 after it has detected that the detected discharge pressure has reached the desired valley pressure.

[0160] At t3, the actual delivery pressure reaches the set pressure of the pressure relief valve, causing the valve to open and release excess fuel pressure. However, since the difference between the actual delivery pressure and the measured delivery pressure is greater than the difference between the set pressure of the pressure relief valve and the desired peak delivery pressure, the measured delivery pressure has not yet reached the desired peak pressure at t2. Consequently, the suction pump remains switched on, the actual delivery pressure remains constant (flattening out) at the current set pressure of the pressure relief valve, and the measured delivery pressure remains constant (flattening out) at a pressure below the desired peak pressure.

[0161] At t4, the controller detects that the suction pump has remained switched on for the calibrated maximum on-time of 1218 and, in response, switches the suction pump OFF, as discussed above with respect to routine 1100. Although the detected discharge pressure has not reached the desired peak pressure, the length of time the suction pump has been switched on without reaching the desired peak value indicates that the sensor output may be inaccurate, and the controller switches the suction pump OFF so that pulsed operation can continue.Such operation contrasts with the second exemplary feedback control strategy discussed here, in which the suction pump is switched off when the measured delivery pressure reaches the desired peak pressure, which can lead to the suction pump remaining switched on even though the actual delivery pressure has exceeded the desired peak pressure and reached the set pressure of the pressure relief valve.

[0162] After t4, the controller continues to switch the suction pump on when the detected delivery pressure has decreased to the desired valley pressure, and continues to switch the suction pump off when the calibrated maximum on-time has been reached. Since the extent to which the sensor measures under-pressure remains constant after t4, the suction pump remains switched on for the calibrated maximum on-time of 1218 every time a voltage pulse is applied, as shown. Thus, despite the sensor being affected and measuring under-pressure, the robust feedback control strategy allows the pulsed operation of the suction pump to occur, thereby improving fuel economy.

[0163] Fig. Figure 12B shows an example characteristic map 1240, which illustrates the same signals as characteristic map 1200 and also represents the suction pump operation in accordance with the third example feedback control strategy. In characteristic map 1240, however, the controller initiates a calibration of the pressure sensor output at t3 after detecting that the suction pump has remained switched on for the calibrated maximum on-time. The curve 1242 represents the calibrated pressure sensor output.

[0164] In the example shown, the controller determines the calibrated pressure sensor output by adding an offset 1244 to the measured discharge pressure. This offset is equal to the difference between the setpoint pressure of the pressure relief valve and the pressure at which the measured discharge pressure leveled off between t2 and t3. From t3 onwards, the feedback control is based on the calibrated pressure sensor output 1242 instead of the measured discharge pressure 1206. When the measured discharge pressure reaches the desired low pressure at t4, the controller does not switch the suction pump on; instead, the suction pump remains off until the calibrated pressure sensor output reaches the desired low pressure at t5. Similarly, the suction pump is switched off as soon as the calibrated pressure sensor output reaches the desired peak pressure at t6, even though the measured discharge pressure has not yet reached the desired peak pressure.As shown, the calibrated pressure sensor output 1242 corresponds closely to the actual delivery pressure 1204 from t3 onwards, so that the suction pump can be controlled accurately and efficiently despite the faulty output of the pressure sensor.

[0165] Fig. Figure 12C shows an example map 1260, which illustrates the same signals as map 1200 and additionally depicts suction pump operation in accordance with the third example feedback control strategy. However, while maps 1200 and 1240 illustrate suction pump operation during sensor impairment, which causes the sensor to measure values ​​that are too low, map 1260 illustrates suction pump operation during sensor impairment, which causes the sensor to measure values ​​that are too high. Map 1260 also illustrates, in curve 1262, the volume of fuel consumed by the combustion engine and provides example values ​​for the actual delivery pressure and the measured delivery pressure. Specifically, in the non-restrictive example shown, the desired low delivery pressure is 400 kPa and the desired high delivery pressure is 600 kPa.

[0166] Shortly after t0, the measured delivery pressure has decreased to the desired valley pressure, and the control unit therefore switches on the suction pump. Because the sensor is measuring values ​​that are too high, the actual delivery pressure at this point is initially lower than the desired valley pressure by a certain amount. This initial amount happens to be smaller than the difference between the desired valley pressure and the fuel vapor pressure. Therefore, when the measured delivery pressure reaches the desired valley pressure, the actual delivery pressure has not yet reached the fuel vapor pressure, and thus the signals have not yet flattened out. After the suction pump has been switched on, the actual delivery pressure decreases at a rate that corresponds to the magnitude of the voltage applied to the suction pump.

[0167] At t1, the measured delivery pressure reaches the desired peak pressure, and in response, the control unit switches the suction pump OFF. Because the pressure sensor is measuring values ​​that are too high, the actual delivery pressure has not yet reached the desired peak pressure. Therefore, the delivery pressure is lower than the required delivery pressure for the current combustion engine operation.

[0168] At t2, the pressure sensor is further affected and begins to measure even higher values, so the detected delivery pressure is a second order higher than the actual delivery pressure, with the second order being larger than the first. This second order happens to be larger than the difference between the desired valley pressure and the fuel vapor pressure. The actual delivery pressure decreases to the desired valley pressure slightly before t2 and then reaches the fuel vapor pressure at t2, causing the signal to flatten. Because the pressure sensor is measuring excessively high values, and because the second order is larger than the difference between the desired valley pressure and the fuel vapor pressure, the detected delivery pressure flattens out at a pressure higher than the desired valley pressure. Since the detected delivery pressure has not reached the desired valley pressure, the control unit does not activate the suction pump, and the actual delivery pressure remains at the fuel vapor pressure.If this were to continue for too long, the combustion engine could stall.

[0169] To prevent stalling, the control system, as discussed above with reference to Routine 1100, monitors the volume of fuel consumed by the internal combustion engine and compares it to a volume V of fuel consumed by the internal combustion engine while the suction pump is off, which should trigger a transition of the suction pump's state from off to on. As stated above, the volume V can be equal to the quotient of the intended pressure drop ΔP between the desired peak pressure and the desired trough pressure and a system stiffness S. In the example shown, the intended pressure drop ΔP is 200 kPa and the system stiffness S is 100 kPa / cc, and the volume V is therefore 2 cc.For example, graph 1262 indicates that 2 cc of fuel were consumed at t1, 4 cc at t4, and so on; this is merely illustrative and does not represent actual cumulative amounts of fuel consumed that would occur during combustion engine operation. In other examples, the controller may reset the consumed volume of fuel V to 0 each time the suction pump is switched off.

[0170] At t1, when the suction pump was switched off, the fuel intake volume was 2 cc. At t4, the fuel intake volume reached 4 cc, meaning 2 cc of fuel had been absorbed since the suction pump was switched off. Since the volume V required to trigger a transition of the suction pump's state to 2 cc is fixed, the controller switches the suction pump on at t4. Although the measured delivery pressure has not yet reached the desired peak pressure, the suction pump is switched on as soon as the required volume V has been absorbed, allowing the pulsed operation to continue.Such an operation contrasts with the second exemplary feedback control strategy discussed here, in which the suction pump is switched on again when the measured delivery pressure reaches the desired valley pressure, which can lead to the suction pump remaining switched off even though the actual delivery pressure has reached the fuel vapor pressure.

[0171] According to t4, the control unit continues to switch the suction pump off when the detected delivery pressure has increased to the desired peak pressure, and switches the suction pump on when the volume of fuel consumed by the combustion engine since the suction pump was switched off reaches 2 cc. Even though the sensor is impaired and measures excessively high values, the robust feedback control strategy thus allows the pulsed operation of the suction pump to be carried out, thereby improving fuel economy.

[0172] Fig.Figure 12D shows an example map 1280, which illustrates the same signals as map 1260 and also represents the suction pump operation in accordance with the third example feedback control strategy. However, in map 1280, after detecting the volume V of fuel consumed since the suction pump was switched off, the control system initiates a calibration of the pressure sensor output. The curve 1282 represents the calibrated pressure sensor output.

[0173] In the example shown, the controller determines the calibrated pressure sensor output by subtracting an offset 1284 from the detected delivery pressure. This offset is equal to the difference between the pressure at which the detected delivery pressure flattened out between t3 and t4 and the fuel vapor pressure. From t4 onwards, the feedback control is performed based on the calibrated pressure sensor output 1282 instead of the detected delivery pressure 1206. When the detected delivery pressure reaches the desired peak pressure at t5, the controller does not switch the suction pump ON; instead, the suction pump remains OFF until the calibrated pressure sensor output reaches the desired peak pressure at t6. Similarly, the suction pump is switched off as soon as the calibrated pressure sensor output reaches the desired valley pressure at t7, even though the detected delivery pressure has not yet reached the desired valley pressure.As shown, the calibrated pressure sensor output 1282 corresponds closely to the actual delivery pressure 1204 from t4 onwards, so that the suction pump can be controlled accurately and efficiently despite the faulty output of the pressure sensor.

[0174] In accordance with the foregoing description, a method for an internal combustion engine, during operation of a suction pump in pulsed mode, involves adjusting a voltage level applied to the suction pump based on an output signal from a pressure sensor downstream of the suction pump and monitoring the output signal for flattening; and, in response to a detection of flattening, indicating a pressure sensor fault and operating the suction pump independently of the pressure sensor output signal. In a first example of the method, monitoring the output signal for flattening includes comparing a time period during which the slope of the output signal is zero with a threshold period.A second example of the method optionally includes the first example and further includes, where operating the suction pump independently of the pressure sensor output signal comprises: operating the suction pump in a continuous mode in which a constant non-zero voltage is applied to the suction pump. A third example of the method optionally includes one or more of the first and second examples and further includes, where operating the suction pump independently of the pressure sensor output signal comprises: operating the suction pump in a pulsed mode in which the voltage level applied to the suction pump is not set based on the pressure sensor output signal.A fourth example of the procedure optionally includes one or more of the first three examples and further includes, where adjusting the voltage level applied to the suction pump based on the pressure sensor output signal comprises adjusting a duty cycle of the voltage pulses based on the output signal. A fifth example of the procedure optionally includes one or more of the first three examples and further includes, where adjusting the duty cycle based on the output signal comprises: increasing the duty cycle when a peak pressure of the output signal is lower than a desired peak pressure, and increasing the duty cycle when the peak pressure is higher than the desired peak pressure.A sixth example of the procedure optionally includes one or more of the first to fifth examples and further includes, wherein adjusting the voltage level applied to the suction pump based on the output signal of the pressure sensor comprises: applying a first, higher voltage to the suction pump when the output signal of the pressure sensor decreases to a desired valley pressure, and applying a second, lower voltage to the suction pump when the output signal of the pressure sensor increases to a desired peak pressure.A seventh example of the method optionally includes one or more of the first to sixth examples and further includes, wherein the pressure sensor error is an error within the normal range, the method further comprising: in response to the output signal increasing above or decreasing below an expected operating range of the pressure sensor, indicating an error of the pressure sensor that is outside the normal range and operating the suction pump independently of the output signal of the pressure sensor.

[0175] Furthermore, in accordance with the foregoing description, an additional method for operating a fuel system of an internal combustion engine may comprise the following: during the operation of the internal combustion engine in steady state, wherein a requested delivery pressure of a fuel suction pump is below a first threshold, reducing a duty cycle of voltage pulses applied to a fuel suction pump until flattening of an output signal of a pressure sensor downstream of the suction pump is detected, and storing the pressure at which the output signal has flattened as the fuel vapor pressure of the fuel system;During steady-state operation of the internal combustion engine, when a requested fuel suction pump delivery pressure exceeds a second threshold, the system increases the duty cycle of voltage pulses applied to the suction pump until a flattening of the pressure sensor output signal is detected, stores the pressure at which the output signal flattened as the setpoint pressure of a pressure relief valve, and adjusts the suction pump operation based on the stored setpoint pressure and fuel vapor pressure.

[0176] In a first example of the additional procedure, adjusting the suction pump operation based on the stored set pressure and fuel vapor pressure includes setting a desired peak suction pump delivery pressure so that it is lower than the stored set pressure by a first predetermined amount, and setting a desired trough suction pump pressure so that it is greater than the stored fuel vapor pressure by a second predetermined amount.A second example of the additional procedure optionally includes the first example and further includes, where adjusting the operation of the suction pump based on the stored set pressure and fuel vapor pressure further includes: during operation of the suction pump in a pulsed mode, applying a first, higher voltage to the suction pump each time the output signal of the pressure sensor decreases to the desired valley pressure, and applying a second, lower voltage to the suction pump each time the output signal of the pressure sensor increases to the desired peak pressure.A third example of the additional procedure optionally includes one or more of the first and second examples and further includes, where setting the suction pump operation based on the stored setpoint pressure and fuel vapor pressure comprises: determining a duty cycle of voltage pulses which, when applied to the suction pump, produces an output signal having a maximum value at the desired peak delivery pressure and a minimum value at the desired trough delivery pressure, and applying voltage pulses to the suction pump with the determined duty cycle. A fourth example of the additional procedure optionally includes one or more of the first through third examples and further includes, where the requested fuel suction pump delivery pressure is directly proportional to the internal combustion engine load.A fifth example of the additional procedure optionally includes one or more of the first to fourth examples and further includes, during the application of voltage pulses to the suction pump with the specified duty cycle, monitoring the output signal of the pressure sensor for flattening and, in response to a detection of flattening, indicating a pressure sensor fault and operating the suction pump independently of the output signal of the pressure sensor.A sixth example of the additional method optionally includes one or more of the first to fifth examples and further includes, wherein operating the suction pump independently of the output signal of the pressure sensor comprises: operating the suction pump in a continuous mode in which a constant non-zero voltage is applied to the suction pump, or operating the suction pump in a pulsed mode in which the voltage pulses applied to the suction pump are not set on the basis of the output signal of the pressure sensor.

[0177] Furthermore, in accordance with the foregoing description, a hybrid vehicle comprises a powertrain comprising an internal combustion engine, an electric motor / generator, a battery, and a transmission coupled to vehicle wheels; a fuel system comprising a fuel tank, a fuel suction pump, a pressure sensor located downstream of an outlet of the suction pump in the fuel system, and a pressure relief valve; a controller comprising non-volatile memory with instructions stored therein that can be executed by a processor to: in response to a request to dynamically determine a fuel vapor pressure of the fuel system during pulsed operation of the suction pump, wherein the requested vehicle wheel torque is above a first threshold, mechanically couple a crankshaft of the internal combustion engine to the electric motor / generator, and reduce the load on the internal combustion engine.until a pressure sensor output signal remains constant for at least a first threshold duration, while electrical energy is converted into torque by the electric motor / generator and the torque is supplied to the vehicle wheels, and storing the pressure at which the output signal remains constant as fuel vapor pressure. In a first example for the hybrid vehicle, the control further includes instructions stored in non-volatile memory and executable by a processor to: in response to a request to dynamically determine a set pressure of the pressure relief valve during pulsed operation of the suction pump, where the requested internal combustion engine output torque is below a first threshold, mechanically couple the crankshaft to the electric motor / generator, and increase the internal combustion engine load until the pressure sensor output signal remains constant for at least a second threshold duration.While part of the combustion engine's output torque is converted into electrical energy by the electric motor / generator and the electrical energy is stored in the battery, and the pressure at which the output signal remains constant is stored as the setpoint pressure. A second example for the hybrid vehicle optionally includes the first example and further includes, where the control further includes instructions stored in non-volatile memory and executable by a processor to: while closed-loop control of the suction pump is performed based on a pressure sensor output signal, monitor the output signal; in response to the output signal remaining constant for at least a threshold duration, indicate an error within the normal range and switch from closed-loop to open-loop control of the suction pump.where the suction pump operation is set independently of the output signal of the pressure sensor. A third example for the hybrid vehicle optionally includes one or more of the first and second examples and further includes instructions, which are stored in non-volatile memory and can be executed by the processor to switch from closed-loop control of the suction pump to open-loop control, where the suction pump operation is set independently of the output signal of the pressure sensor, and instructions for applying a non-zero constant voltage to the suction pump. A fourth example for the hybrid vehicle optionally includes one or more of the first to third examples and further includes instructions, where the control further includes instructions, which are stored in non-volatile memory and can be executed by a processor to do the following: after storing the pressure at which the output signal remains constant,Setting a duty cycle of voltage pulses applied to the suction pump based on a desired pressure differential between the fuel vapor pressure and the delivery pressure of the suction pump, as fuel vapor pressure.

[0178] Furthermore, in accordance with the foregoing description, a method for operating a fuel system of an internal combustion engine during pulsed operation of a suction pump comprises switching off the suction pump when a detected delivery pressure increases to a desired peak pressure or when a suction pump's on-time reaches a calibrated maximum, and switching on the suction pump when either the detected delivery pressure decreases to a desired valley pressure or a volume of fuel consumed by the internal combustion engine reaches a predetermined volume. A first example of this method involves determining the predetermined volume as a function of a difference between the desired peak pressure and the desired valley pressure and a stiffness of the fuel system.A second example of this method optionally includes the first example and further includes, where the predetermined volume is set equal to the quotient of the difference between the desired peak pressure and the desired valley pressure and the stiffness of the fuel system. A third example of this method optionally includes one or more of the first and second examples and further includes determining the stiffness of the fuel system as a function of a fluid density within the fuel system. This method further includes, in response to the suction pump's on-time reaching the calibrated maximum, indicating a pressure sensor error within the normal range and initiating a calibration of the detected delivery pressure, wherein the calibration involves adding an offset to the detected delivery pressure.A fifth example of this procedure optionally includes one or more of the first four examples and further includes, where the offset is equal to the difference between a setpoint pressure of a pressure relief valve and the detected delivery pressure when the on-time has reached the calibrated maximum. This procedure further includes, in response to the volume of fuel consumed by the internal combustion engine reaching the predetermined volume, indicating a pressure sensor error within the normal range and initiating a calibration of the detected delivery pressure, wherein the calibration involves subtracting an offset from the detected delivery pressure.A seventh example of this method optionally includes one or more of the first to sixth examples and further includes, where the offset is equal to the difference between the detected delivery pressure when the volume of fuel taken in by the internal combustion engine has reached the predetermined volume and a fuel vapor pressure of the fuel system.

[0179] Yet another method in accordance with the present disclosure involves, while performing closed-loop control of a suction pump based on an output signal from a pressure sensor located downstream of the suction pump, monitoring the output signal; in response to the output signal remaining constant for at least a first threshold duration while the suction pump is switched on, switching off the suction pump, calibrating the output signal based on the pressure at which the output signal remained constant, and subsequently performing closed-loop control of the suction pump based on the calibrated output signal; in response to the output signal remaining constant for at least a second threshold duration while the suction pump is switched off, switching on the suction pump, and calibrating the output signal based on the pressure at which the output signal remained constant.and subsequent closed-loop control of the suction pump based on the calibrated output signal. A first example of this procedure includes, where calibrating the output signal based on the pressure at which the output signal remained constant while the suction pump was switched on, adding a first offset to the output signal, the first offset being equal to the difference between a setpoint pressure of a pressure relief valve and the pressure at which the output signal remained constant while the suction pump was switched on. A second example of this procedure optionally includes the first example and further includes, where calibrating the output signal based on the pressure at which the output signal remained constant while the suction pump was switched off, subtracting a second offset from the output signal, the second offset being equal to the difference between the pressure,where the output signal remained constant while the suction pump was switched off, and a fuel vapor pressure of the fuel system. A third example of this procedure optionally includes one or more of the first and second examples and further includes determining the first threshold duration by subtracting a suction pump on-time before the output signal reached the pressure at which it remained constant from a calibrated maximum on-time. A fourth example of this procedure optionally includes one or more of the first to third examples and further includes determining the second threshold duration based on a current rate of fuel intake by the internal combustion engine and a difference between a predetermined volume of fuel and a volume of fuel that has been taken in by the suction pump since the suction pump was switched off before the output signal reached the pressure.where it remained constant. A fifth example of this method optionally includes one or more of the first to fourth examples and further includes, wherein the predetermined volume of fuel is determined as a function of a difference between a desired peak delivery pressure and a desired trough delivery pressure and a stiffness of the fuel system. A sixth example of this method optionally includes one or more of the first to fifth examples and further includes, wherein the predetermined volume is set equal to the quotient of the difference between the desired peak pressure and the desired trough pressure and the stiffness of the fuel system, and wherein the stiffness of the fuel system is determined as a function of a density of fluid within the fuel system.

[0180] In addition, in accordance with the foregoing description, a hybrid vehicle comprises a powertrain comprising an internal combustion engine, an electric motor / generator, a battery, and a transmission coupled to the vehicle's wheels; a fuel system comprising a fuel tank, a fuel suction pump, a pressure sensor located downstream of an outlet of the suction pump in the fuel system, and a pressure relief valve; and a controller comprising non-volatile memory containing instructions executable by a processor to: monitor, during pulsed operation of a suction pump, a volume of fuel being drawn in by the internal combustion engine while the suction pump is off; if the volume of fuel being drawn in by the internal combustion engine while the suction pump is off reaches a predetermined volume,Before the pressure sensor output signal has decreased to a desired valley pressure, the suction pump is switched on, the pressure sensor output signal is stored as the first stored value, and a dynamic determination of the fuel vapor pressure of the fuel system is requested; if a requested vehicle wheel torque is above a first threshold, a crankshaft of the internal combustion engine is mechanically coupled to the electric motor / generator, the internal combustion engine load is reduced until the pressure sensor output signal remains constant for at least a first threshold duration, while electrical energy is converted into torque by the electric motor / generator and the torque is supplied to the vehicle wheels, and the pressure at which the output signal remains constant is stored as the updated fuel vapor pressure; and if the updated fuel vapor pressure is less than the first stored value, it is indicated.that the pressure sensor is measuring values ​​that are too high. In a first example for the hybrid vehicle, the control system further includes instructions stored in non-volatile memory, which can be executed by a processor to: monitor the pump's on-time during pulsed operation of the suction pump; if the suction pump's on-time reaches a calibrated maximum on-time before the pressure sensor's output signal has increased to a desired peak pressure, switch off the suction pump, store the pressure sensor's output signal as a second stored value, and request a dynamic determination of a target pressure for the pressure relief valve; if the requested internal combustion engine output torque is below a second threshold, mechanically couple the crankshaft to the electric motor / generator, and increase the internal combustion engine load until the pressure sensor's output signal remains constant for at least a second threshold duration.While part of the combustion engine's output torque is converted into electrical energy by the electric motor / generator and the electrical energy is stored in the battery, the pressure at which the output signal remains constant is stored as the updated setpoint pressure; and if the updated setpoint pressure is greater than the second stored value, it indicates that the pressure sensor is measuring values ​​that are too low. A second example for the hybrid vehicle optionally includes the first example and further includes, where the control further includes instructions stored in non-volatile memory and executable by a processor to: in response to an indication that the pressure sensor is measuring values ​​that are too high, initiate a calibration of the pressure sensor's output signal.wherein the calibration involves subtracting a first offset from the output signal of the pressure sensor. A third example for the hybrid vehicle optionally includes one or more of the first and second examples and further includes, wherein the controller further includes instructions stored in non-volatile memory and executable by a processor to: in response to a notification that the pressure sensor is measuring values ​​too low, initiate a calibration of the output signal of the pressure sensor, wherein the calibration involves adding a second offset to the output signal of the pressure sensor. A fourth example for the hybrid vehicle optionally includes one or more of the first to third examples and further includes, wherein the controller further includes instructions,which are stored in non-volatile memory and can be executed by a processor to do the following: set the first offset equal to the difference between the first stored value and the updated fuel vapor pressure, and set the second offset equal to the difference between the updated target pressure and the second stored value.

[0181] In accordance with the methods and systems disclosed herein, within-normal-range errors of a pressure sensor measuring the delivery pressure of a suction pump can be accurately detected. Upon detection of an within-normal-range error in the pressure sensor, the suction pump control can be switched from a closed-loop control strategy, in which a duty cycle of voltage pulses applied to the suction pump is set based on feedback from the pressure sensor, to an open-loop control strategy, in which the voltage applied to the suction pump is independent of feedback from the pressure sensor.Remarkably, the detection of faults within the normal range can include the detection of a flattening of the measured pressure without considering the magnitude of the measured pressure. This has the technical effect of detecting a malfunction of the pressure sensor even if the sensor is operating within its expected range, and can advantageously reduce the complexity of the control system. Furthermore, switching from closed-loop control to open-loop control of the suction pump after the detection of a fault within the normal range allows the fuel system to continue providing the commanded delivery pressure despite the faulty pressure sensor.Alternatively, in accordance with the methods and systems disclosed herein, a robust feedback control strategy can be implemented which allows pulsed operation of the suction pump with closed control loop to continue even when flattening of the pressure sensor output indicates that the sensor is impaired.

[0182] In another embodiment, a method in accordance with the present disclosure may include: adjusting the operation of a fuel suction pump of a fuel system of an internal combustion engine with a control for dynamically determining a setpoint pressure of a pressure relief valve in the fuel system and a fuel vapor pressure of the fuel system; adjusting the operation of the suction pump to maintain a first desired range between a maximum delivery pressure and the setpoint pressure and a second desired range between a minimum delivery pressure and the fuel vapor pressure; and monitoring the delivery pressure with a pressure sensor located downstream of the suction pump for deviations from an expected slope of the detected delivery pressure signal. Such deviations may include the signal having a slope of zero for a period exceeding a predetermined threshold duration.

[0183] It should be noted that the exemplary control and estimation routines contained herein can be used with various internal combustion engine and / or vehicle system designs. The control methods and routines disclosed herein can be stored as executable instructions in non-volatile memory and executed by the control system, including the controller, in combination with the various sensors, actuators, and other internal combustion engine hardware. The specific routines described herein can represent one or more from any number of processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, and the like. Accordingly, various illustrated actions, processes, and / or functions can be performed in the illustrated sequence or in parallel, or in some cases, omitted.Likewise, the processing sequence is not strictly necessary to achieve the features and advantages of the exemplary embodiments described here, but is provided for the sake of clarity and description. One or more of the illustrated actions, processes, and / or functions can be performed repeatedly, depending on the specific strategy employed. Furthermore, the described actions, processes, and / or functions can graphically represent code that is programmed into non-volatile memory of the computer-readable storage medium in the internal combustion engine control system, with the described actions being executed by carrying out the instructions in a system that includes the various internal combustion engine hardware components in combination with the electronic control unit.

[0184] It is understood that the interpretations and routines disclosed herein are exemplary in nature and that these specific embodiments are not to be interpreted in a limiting sense, as numerous variations are possible. For example, the aforementioned technology can be applied to V-6, I-4, I-6, V-12, 4-cylinder boxer, and other types of internal combustion engines. The subject matter of this disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and interpretations, and other features, functions, and / or properties disclosed herein.

[0185] The following claims describe, in particular, certain combinations and subcombinations that are considered novel and not obvious. These claims may refer to "one" element, "a first" element, or the equivalent thereof. Such claims are to be understood as including one or more such elements and 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 by amending the present claims or by filing new claims in this or a related application.Such patent claims are also considered to be included in the subject matter of the present disclosure, irrespective of whether they have a broader, narrower, the same or different scope compared to the original patent claims.

Claims

[1] Method for operating a fuel system (8) of an internal combustion engine with a pressure sensor (234) arranged downstream of a suction pump (208) for measuring a delivery pressure, comprising: During pulsed operation of the suction pump (208), the suction pump (208) switches off when a detected delivery pressure increases to a desired peak pressure or when an on-time of the suction pump (208) reaches a calibrated maximum, and switches on the suction pump (208) when either the detected delivery pressure decreases to a desired trough pressure or a volume of fuel taken in by the internal combustion engine reaches a predetermined volume. characterized by , that in response to the fact that the on-time of the suction pump (208) reaches the calibrated maximum, indicating an error of the pressure sensor (234) within the normal range and initiating a calibration of the detected delivery pressure, wherein the calibration involves adding an offset to the detected delivery pressure and In response to the volume of fuel consumed by the internal combustion engine reaching the predetermined volume, indicating an error of the pressure sensor within the normal range and initiating a calibration of the detected delivery pressure, wherein the calibration involves subtracting an offset from the detected delivery pressure. [2] Method according to claim 1, further comprising determining the predetermined volume as a function of a difference between the desired peak pressure (307) and the desired valley pressure and a stiffness (S) of the fuel system (8). [3] Method according to claim 2, wherein the predetermined volume is set equal to the quotient of the difference between the desired peak pressure (307) and the desired valley pressure and the stiffness (S) of the fuel system (8). [4] Method according to claim 3, further comprising determining the stiffness (S) of the fuel system (8) as a function of a density of fluid within the fuel system (8). [5] Method according to claim 1, wherein the offset is equal to the difference between a set pressure (302) of a pressure relief valve and the detected delivery pressure when the on-time has reached the calibrated maximum. [6] Method according to claim 1, further comprising performing subsequent control of the suction pump (208) with closed control loop on the basis of the detected delivery pressure after calibration. [7] Method according to claim 1, wherein the offset is equal to the difference between the detected delivery pressure when the volume of fuel taken in by the internal combustion engine has reached the predetermined volume and a fuel vapor pressure of the fuel system (8). [8] Method according to claim 1, further comprising performing subsequent control of the suction pump (208) with closed control loop on the basis of the detected delivery pressure after calibration. [9] Hybrid vehicle, comprising: a powertrain comprising an internal combustion engine (10), an electric motor / generator (52), a battery (58) and a transmission (54) coupled to vehicle wheels (55); a fuel system (8) comprising a fuel tank (202), a fuel suction pump (208), a pressure sensor (234) arranged downstream of an outlet of the suction pump (208) in the fuel system (8), and a pressure relief valve (211); and a controller (12) which includes non-volatile memory (110) containing instructions stored therein which can be executed by a processor to do the following: During pulsed operation of a suction pump, monitoring a volume of fuel taken in by the internal combustion engine (10) while the suction pump (208) is switched off; If the volume of fuel taken in by the internal combustion engine (10) while the suction pump (208) is switched off reaches a predetermined volume before an output signal of the pressure sensor (234) has decreased to a desired valley pressure, switch on the suction pump (208), store the value of the output signal of the pressure sensor (234) as the first stored value and request a dynamic determination of a fuel vapor pressure of the fuel system (8); If a requested vehicle wheel torque exceeds a first threshold, mechanical coupling of a crankshaft (140) of the internal combustion engine (10) to the electric motor / generator (52), reduction of the internal combustion engine load until the output signal of the pressure sensor (234) remains constant for at least a first threshold duration, while electrical energy is converted into torque by the electric motor / generator (52) and the torque is supplied to the vehicle wheels (55), and storage of the pressure at which the output signal remains constant as updated fuel vapor pressure; and If the updated fuel vapor pressure is less than the first stored value, indicate that the pressure sensor (234) is measuring values ​​that are too high. [10] Hybrid vehicle according to claim 9, wherein the control (12) further comprises instructions which are stored in non-volatile memory (110) and which can be executed by a processor to: During pulsed operation of the suction pump (208) monitoring of an on-time of the suction pump (208); If the on-time of the suction pump (208) reaches a calibrated maximum on-time before the output signal of the pressure sensor (234) has increased to a desired peak pressure, switch off the suction pump (208), store the value of the output signal of the pressure sensor (234) as the second stored value and request dynamic determination of a setpoint pressure (302) of the pressure relief valve (211); If the requested output torque of the internal combustion engine (10) is below a second threshold, mechanical coupling of the crankshaft (140) to the electric motor / generator (52), increasing the internal combustion engine load until the output signal of the pressure sensor (234) remains constant for at least a second threshold duration, while part of the output torque of the internal combustion engine (10) is converted into electrical energy by the electric motor / generator (52) and the electrical energy is stored in the battery (58), and storing the pressure at which the output signal remains constant as the updated setpoint pressure (302); and If the updated target pressure (302) is greater than the second stored value, indicate that the pressure sensor (234) is measuring values ​​that are too low. [11] Hybrid vehicle according to claim 10, wherein the control (12) further comprises instructions which are stored in non-volatile memory (110) and which can be executed by a processor to: In response to a report that the pressure sensor is measuring excessively high values, initiating a calibration of the pressure sensor's output signal, wherein the calibration involves subtracting a first offset from the pressure sensor's output signal. [12] Hybrid vehicle according to claim 11, wherein the control (12) further comprises instructions which are stored in non-volatile memory (110) and which can be executed by a processor to: In response to a report that the pressure sensor (234) is measuring values ​​that are too low, initiating a calibration of the output signal of the pressure sensor (234), wherein the calibration involves adding a second offset to the output signal of the pressure sensor (234). [13] Hybrid vehicle according to claim 12, wherein the control (12) further comprises instructions stored in non-volatile memory (110) and executable by a processor to: set the first offset equal to the difference between the first stored value and the updated fuel vapor pressure and set the second offset equal to the difference between the updated target pressure (302) and the second stored value.

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