JP2013253560A - Fuel supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel supply device capable of detecting abnormal conditions of a fuel pressure sensor early and precisely.SOLUTION: A fuel supply device comprises an ECU performing feedback control of the driving of an electric feed pump so that an actual fuel pressure detected by a fuel pressure sensor becomes a target fuel pressure when the fuel pressure sensor is not abnormal, estimating the fuel pressure on the basis of a driving current of the feed pump when the fuel pressure sensor is abnormal, performing the feedback control of the driving of the feed pump via an FPC so that the estimated fuel pressure becomes the target fuel pressure, and determining whether or not the fuel pressure sensor is abnormal. The ECU estimates the fuel pressure on the basis of the driving current of the feed pump when an air-fuel ratio of the exhaust gas exhausted from an engine is not the theoretical air-fuel ratio, and determines that the fuel pressure sensor is abnormal when the fuel pressure detected by the fuel pressure sensor diverges from the estimated fuel pressure.

Description

  The present invention relates to a fuel supply device that injects and supplies fuel to an internal combustion engine.

  In general, the fuel supply device is configured to pump fuel stored in a fuel tank to a fuel injection valve by a fuel pump, and to inject and supply the pumped fuel from the fuel injection valve to an internal combustion engine.

  Conventionally, as this type of fuel supply device, the actual fuel pressure and the target fuel pressure are set so that the actual fuel pressure detected by the fuel pressure sensor (hereinafter referred to as the actual fuel pressure) matches the target fuel pressure (hereinafter referred to as the target fuel pressure). There is known a fuel supply device that feedback-controls the discharge amount of a fuel pump based on the deviation of the above (for example, see Patent Document 1).

  The fuel supply device described in Patent Document 1 suppresses that the internal combustion engine is operated at a lean air-fuel ratio because the actual fuel injection amount is insufficient than required even when the fuel pressure sensor fails. In addition, it has a fail-safe function for driving and controlling the fuel pump without using the output value from the fuel pressure sensor when the fuel pressure sensor fails (when abnormality of the fuel pressure sensor is detected). In Patent Document 1, as a specific fail-safe function, when abnormality of the fuel pressure sensor is detected, feedback control of the fuel pump using the output value of the fuel pressure sensor is prohibited, and the discharge amount of the fuel pump is set to the maximum discharge amount or the target fuel pressure. It is disclosed that the discharge amount is fixed to such a degree that can be obtained.

  Here, in the fuel supply device described in Patent Document 1, in order to detect abnormality of the fuel pressure sensor, a normal range that is greater than or equal to the set value 1 and less than the set value 2 can be determined that the output value of the fuel pressure sensor is normal. When the state in which the actual output value is outside the normal range continues for a predetermined time or more, it is determined that the fuel pressure sensor is abnormal. The set value 1 described above is set to a value that the output value of the fuel pressure sensor does not fall below when the fuel pressure sensor is normal, and the set value 2 does not exceed the output value when the fuel pressure sensor is normal. Is set to a value.

JP 2011-085147 A

  However, in the above-described conventional fuel supply device, it is not possible to detect abnormality of the fuel pressure sensor unless monitoring whether the output value of the fuel pressure sensor is outside the normal range continues for a predetermined time or more. Therefore, there is a problem that abnormality detection of the fuel pressure sensor cannot be performed at an early stage.

  Also, it is determined that the fuel pressure sensor is abnormal only when the output value of the fuel pressure sensor is out of the normal range, so if the output value of the fuel pressure sensor deviates from the actual fuel pressure within the normal range, There was a problem that this could not be determined as an abnormality of the fuel pressure sensor.

  The present invention has been made to solve the above-described conventional problems, and provides a fuel supply device that can detect an abnormality of a fuel pressure sensor earlier and more accurately than in the past. Objective.

  In order to achieve the above object, the fuel supply apparatus according to the present invention includes: (1) an electric fuel pump that pumps fuel stored in a fuel tank to an internal combustion engine; and a fuel pressure of fuel pumped to the internal combustion engine. A fuel pressure sensor to be detected, an abnormality determining means for determining whether or not the fuel pressure sensor is abnormal, and an actual fuel pressure detected by the fuel pressure sensor when the fuel pressure sensor is not abnormal becomes a target target fuel pressure. While the fuel pump drive is feedback controlled, when the fuel pressure sensor is abnormal, the fuel pressure is estimated based on the drive current of the fuel pump, and the estimated fuel pressure becomes the target fuel pressure. A pump drive control means for feedback-controlling the drive of the engine, wherein the abnormality determination means has a predetermined air-fuel ratio of the exhaust gas discharged from the internal combustion engine When the fuel pressure is not constant, the fuel pressure is estimated based on the drive current, and the fuel pressure sensor is abnormal when the fuel pressure detected by the fuel pressure sensor deviates from the estimated fuel pressure. It has a configuration for determining.

  With this configuration, the fuel supply apparatus according to the present invention estimates the fuel pressure based on the driving current of the fuel pump and detects it by the fuel pressure sensor when the air-fuel ratio of the exhaust gas is not a predetermined air-fuel ratio. When the measured fuel pressure deviates from the estimated fuel pressure, it is determined that the fuel pressure sensor is abnormal.

  Therefore, when the air-fuel ratio of the exhaust gas is not a predetermined air-fuel ratio, it is possible to perform abnormality determination processing of the fuel pressure sensor early on the assumption that an abnormality has occurred in the fuel pressure sensor. . Thereby, abnormality of a fuel pressure sensor can be detected at an early stage. For example, when the fuel pressure detected by the fuel pressure sensor is higher than the actual fuel pressure due to a failure of the fuel pressure sensor or the like, a lot of fuel is injected into the internal combustion engine, so the exhaust gas becomes rich. That is, by detecting such a rich state of exhaust gas, it can be assumed that an abnormality has occurred in the fuel pressure sensor. Therefore, it is possible to detect abnormality of the fuel pressure sensor at an early stage by performing abnormality determination processing of the fuel pressure sensor in such a case.

  In addition, since the fuel pressure sensor abnormality is determined by comparing the estimated fuel pressure with the fuel pressure detected by the fuel pressure sensor, the fuel pressure sensor abnormality can be accurately detected.

  Further, the fuel supply device according to the present invention is the fuel supply device according to (1), wherein (2) the abnormality determination means sets the fuel pressure when the applied voltage applied to the fuel pump is constant. The fuel pressure is estimated from the characteristics of the drive current that varies accordingly.

  With this configuration, the fuel supply apparatus according to the present invention estimates the fuel pressure from the characteristics of the drive current that varies according to the fuel pressure when the applied voltage of the fuel pump is constant, and therefore accurately uses values other than the fuel pressure sensor. The fuel pressure can be estimated.

  The fuel supply device according to the present invention is the fuel supply device according to (1) or (2), wherein (3) the pump drive control means is configured to adjust the drive current when the fuel pressure sensor is not abnormal. The fuel pressure is estimated based on the fuel pressure, and when the estimated fuel pressure deviates from the actual fuel pressure detected by the fuel pressure sensor, the feedback control using the estimated fuel pressure is prohibited.

  With this configuration, when the fuel pressure sensor is not abnormal and the estimated fuel pressure deviates from the actual fuel pressure detected by the fuel pressure sensor, the fuel supply device according to the present invention has some abnormality in the fuel pressure estimation process itself. Can be determined to have occurred. In this case, if the estimated fuel pressure is used, the fuel pump cannot be driven at an appropriate fuel pressure, so that feedback control related to driving the fuel pump using the estimated fuel pressure is prohibited. Thereby, feedback control related to driving of the fuel pump using the estimated fuel pressure can be performed only when the fuel pressure estimation process is reliable.

  ADVANTAGE OF THE INVENTION According to this invention, the fuel supply apparatus which can detect the abnormality of a fuel pressure sensor early and correctly can be provided.

1 is a schematic configuration diagram of a fuel supply system to which a fuel supply apparatus according to an embodiment of the present invention is applied. It is a graph which shows the relationship between a drive current and fuel pressure when the applied voltage of a feed pump is made constant. It is a flowchart which shows drive control of a feed pump. It is a flowchart which shows the fuel pressure sensor abnormality determination process in FIG. It is a flowchart which shows the abnormality determination process of the estimation process of a fuel pressure. It is a flowchart which shows the electricity supply abnormality determination process of a feed pump. It is a graph which shows the relationship between the drive current and applied voltage when a fuel pressure is made constant. It is a graph which shows the change of the applied voltage at the time of the electricity supply abnormality of a feed pump.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  In the present embodiment, an example in which the fuel supply apparatus according to the present invention is applied to a fuel supply system for an internal combustion engine mounted on a vehicle as a driving force source will be described.

  As shown in FIG. 1, the fuel supply system includes a first fuel supply device 20 that supplies low pressure side fuel for port injection to the engine 10, and a cylinder that pressurizes the fuel supplied from the first fuel supply device 20 A second fuel supply device 30 that supplies high-pressure side fuel for internal injection and a fuel pressure variable device 40 that variably controls the supply pressure of low-pressure side fuel according to the operating state of the engine 10 are configured.

  The engine 10 is a multi-cylinder internal combustion engine mounted on a vehicle such as an automobile, for example, an in-line four-cylinder four-cycle gasoline engine. The engine 10 is not limited to an in-line four-cylinder engine, and is configured by various types of engines such as an in-line six-cylinder engine, a V-type six-cylinder engine, a V-type 12-cylinder engine, or a horizontally opposed six-cylinder engine. Also good.

  The engine 10 normally operates in a fuel consumption state in which rotational power is output from a crankshaft (not shown) while consuming fuel, for example, gasoline, in the combustion chamber 13 in each cylinder 11.

  Each cylinder 11 accommodates a piston 12 and defines a combustion chamber 13. Each cylinder 11 is equipped with an intake valve 14 and an exhaust valve 15 that are opened and closed at a predetermined timing.

  The engine 10 is provided with a plurality of spark plugs 16 corresponding to the plurality of cylinders 11 so as to be exposed in the corresponding combustion chambers 13. Further, the engine 10 is equipped with an ignition device (not shown) having an ignition coil for igniting the ignition plug 16 and an electronic control throttle motor (not shown) for variably controlling the throttle opening.

  A purification device 19 including an exhaust gas purification catalyst that purifies harmful components such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx) is provided on the exhaust passage 18 of the engine 10. . Therefore, the exhaust gas discharged from the engine 10 is discharged to the outside air through the purification device 19.

  The first fuel supply device 20 includes a fuel tank 21, a feed pump 22, a relief valve 23, a low pressure fuel pipe 24, a low pressure side delivery pipe 25, a fuel pressure sensor 26, and a plurality of port injection injectors 27. A fuel pump controller (hereinafter simply referred to as FPC) 28 and a jet pump 29 are included.

  The fuel tank 21 has, for example, a predetermined volume containing the sub tank 21a, and can be replenished with fuel from the outside. The fuel tank 21 may be a vertical type or the like that is divided into a plurality of tank portions corresponding to the inside and the outside of the sub tank according to the shape of the bottom wall.

  The feed pump 22 is an electric fuel pump that pumps fuel stored in the fuel tank 21 to the engine 10. The feed pump 22 in the present embodiment constitutes a fuel pump according to the present invention.

  This feed pump 22 is of a variable discharge capacity (discharge amount and discharge pressure) type that can pump up the fuel in the fuel tank 21 and pressurize it to a predetermined feed fuel pressure or higher, and is constituted by a circumferential flow pump, for example. Yes. The feed pump 22 has an impeller for operating the pump and a built-in motor that drives the pump operating part. Therefore, the feed pump 22 changes at least one of the rotational speed and rotational torque of the impeller for operating the pump in accordance with, for example, the drive voltage of the built-in motor, that is, the applied voltage applied to the feed pump 22 and the load torque. Thus, the discharge capacity per unit time, that is, the discharge pressure and the discharge amount can be changed.

  The relief valve 23 opens when the pressure of the fuel discharged from the feed pump 22 into the low-pressure fuel pipe 24 (hereinafter referred to as fuel pressure) rises to reach a preset upper limit pressure, and the fuel pressure is reduced. It is a pressure control valve having a safety valve function for limiting to a set upper limit pressure or less. The set upper limit pressure is a fuel pressure that is high enough to easily induce fuel leakage from the port injection injector 27 when the fuel pressure exceeds the set upper limit pressure, and is set to several hundred kPa, for example. .

  The low-pressure delivery pipe 25 is made of metal that introduces fuel pressurized by the feed pump 22 through the low-pressure fuel pipe 24 and stores a predetermined amount of fuel. The low-pressure delivery pipe 25 has a function of absorbing fuel pressure pulsation by bending according to the fuel pressure and a function of accumulating fuel pressure necessary for port injection from the port injection injector 27. Yes.

  The fuel pressure sensor 26 is provided in the low-pressure delivery pipe 25 and detects the fuel pressure of the fuel pumped to the engine 10, that is, the fuel pressure (Pf) in the low-pressure delivery pipe 25.

  The plurality of port injection injectors 27 are provided corresponding to the plurality of cylinders 11, and end portions on the respective injection hole sides are exposed in the intake ports 11 a corresponding to the respective cylinders 11. These injectors 27 are connected to the low-pressure delivery pipe 25 and wired to a driver circuit (not shown) on the ECU 50 side so as to be opened by a port injection drive signal from the ECU 50. When the plurality of injectors 27 are sequentially driven by the port injection drive signal, the fuel accumulated and stored in the low-pressure delivery pipe 25 from a part of the opened injectors 27 is the port injection drive signal. Is injected into the corresponding intake port 11a in accordance with the valve opening time ratio (duty ratio) every predetermined time.

  The FPC 28 drives the feed pump 22 according to the applied voltage commanded from the ECU 50. Thereby, the discharge capability (discharge amount and discharge pressure) of the feed pump 22 is variably controlled.

  The jet pump 29 discharges fuel from the low pressure fuel pipe 24 into the sub tank 21a of the fuel tank 21 through an internal venturi (not shown). The jet pump 29 pumps the fuel stored in the fuel tank 21 and outside the sub tank 21a into the sub tank 21a by the venturi effect corresponding to the discharge flow rate. The jet pump 29 serves as a means for introducing fuel into the sub tank 21 a by the amount of fuel consumed successively by the engine 10.

  The second fuel supply device 30 includes a plunger-type fuel pressurizing pump 31, an electromagnetic spill-type intake control valve 32, a high-pressure fuel pipe 35, a high-pressure side delivery pipe 36, and a plurality of in-cylinder injectors 37. It is comprised including.

  The fuel pressurization pump 31 reciprocates a plunger (not shown) to change the volume of the fuel pressurization chamber, so that the fuel pressurized by the feed pump 22 is sucked into the fuel pressurization chamber through the high-pressure fuel pipe 35. It has become. The fuel pressurizing pump 31 pressurizes the fuel sucked into the fuel pressurizing chamber under the closed state of the suction control valve 32 and can discharge the fuel at a high pressure capable of direct in-cylinder fuel injection. Yes. The fuel pressurization pump 31 is driven by rotational power from a crankshaft (not shown) of the engine 10.

  The suction control valve 32 is selectively excited and opened during the volume increase period of the fuel pressurization chamber of the fuel pressurization pump 31 and during the volume decrease period of the fuel pressurization chamber of the fuel pressurization pump 31. The valve can be closed only for a necessary period according to the discharge amount (discharge fuel flow rate). Further, the suction control valve 32 can maintain its open state so that the fuel pressurization operation of the fuel pressurization pump 31 is disabled. The electromagnetic spill-type suction control valve 32 is always opened when de-energized.

  The high-pressure delivery pipe 36 is made of a highly rigid metal that introduces and stores fuel pressurized to high pressure by the fuel pressurizing pump 31, and has a function of accumulating fuel pressure necessary for direct fuel injection in the cylinder. doing.

  The plurality of in-cylinder injectors 37 are connected to the high-pressure delivery pipe 36 and wired to a driver circuit on the ECU 50 side so as to be opened by an in-cylinder injection drive signal from the ECU 50. The injectors 37 respectively store the high-pressure fuel accumulated and stored in the high-pressure delivery pipe 36 at the time of valve opening according to the valve opening time ratio (duty ratio) for each predetermined time by the in-cylinder injection drive signal. The fuel is injected into the cylinder 11.

  The fuel pressure varying device 40 includes a feed pump 22 and an FPC 28, and an ECU 50 that variably controls the discharge capacity of the feed pump 22 via the FPC 28. The fuel pressure variable device 40 exhibits a function of variably controlling the discharge capacity of the feed pump 22 based on the operation state of the vehicle and the engine 10 and the requested operation input from the driver.

  The ECU 50 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory) and a backup memory (for example, a nonvolatile memory or a RAM backed up by a battery), an input interface circuit, and an output interface circuit. Etc. are configured.

  Various sensors such as an accelerator opening sensor 61, an air flow meter 62, a crank angle sensor 63, a water temperature sensor 64, an A / F sensor 65, and a fuel pressure sensor 26 are connected to the input interface circuit of the ECU 50.

The accelerator opening sensor 61 detects a depression rate of an accelerator pedal (not shown) mounted on the vehicle as an accelerator opening (Accp). The air flow meter 62 detects the intake air amount (Qa) of the engine 10. The crank angle sensor 63 detects a crank angle (CA) from which the engine speed of the engine 10 can be calculated. The water temperature sensor 64 detects the coolant temperature (Thw) of the engine 10. The A / F sensor 65 has an output characteristic proportional to the air-fuel ratio, and can continuously detect an air-fuel ratio over a relatively wide range. In the present embodiment, the A / F sensor 65 having a linear characteristic with respect to the air-fuel ratio is used as the air-fuel ratio sensor. However, the present invention is not limited to this, and a characteristic (a An O ₂ sensor having a Z characteristic may be used.

  The output interface circuit of the ECU 50 includes port injectors and in-cylinder injectors 27 and 37, electromagnetic drive units (not shown) of the intake control valve 32, an FPC 28, an electronic throttle motor, and the like described above via a driver circuit (not shown). The ignition device is connected.

  The ECU 50 can execute known electronic throttle control, fuel injection amount control, ignition timing control, and the like by executing a control program stored in the ROM. For example, the ECU 50 calculates the basic injection amount required for each combustion based on the intake air amount detected by the air flow meter and the engine speed detected by the crank angle sensor, and further according to the operating state of the engine 10. Further, the fuel injection amount subjected to various corrections, air-fuel ratio feedback correction, and the like can be calculated, and the injectors 27 and 37 corresponding to the fuel injection time corresponding to the fuel injection amount can be driven to open.

  Further, the ECU 50 is configured to calculate a target fuel pressure based on the driving state of the vehicle and the engine 10 and a requested operation input from the driver. The ECU 50 feedback-controls the applied voltage of the feed pump 22 in accordance with the deviation between the fuel pressures so that the calculated target fuel pressure and the actual fuel pressure in the low-pressure delivery pipe 25 detected by the fuel pressure sensor 26 match. . The ECU 50 outputs to the FPC 28 a command signal for the applied voltage of the feed pump 22 that is feedback-controlled so that the actual fuel pressure becomes the target fuel pressure. The FPC 28 drives the feed pump 22 according to the applied voltage commanded from the ECU 50. Thereby, the feed pump 22 changes the rotational speed and rotational torque (of course, both speed and torque) of the impeller for operating the pump, and its discharge capacity changes. Thus, the feed pump 22 is driven so that the actual fuel pressure in the low-pressure delivery pipe 25 changes in a direction to follow the target fuel pressure in accordance with the applied voltage commanded from the ECU 50. That is, the ECU 50 can variably control the discharge capability (discharge amount and discharge pressure) of the feed pump 22 via the FPC 28 so that the actual fuel pressure in the low-pressure delivery pipe 25 can follow the target fuel pressure. ing.

  Further, the FPC 28 has a voltage detector (not shown) that detects the terminal voltage of the built-in motor of the feed pump 22 and a current detector (not shown) that detects the drive current flowing through the built-in motor of the feed pump 22. Is provided. The FPC 28 is connected to the ECU 50 so as to be capable of two-way communication, and can transmit information (voltage information, drive current information) related to the terminal voltage and the drive current detected by the voltage detection unit and the current detection unit to the ECU 50. It is configured.

  Here, conventionally, if the above-described fuel pressure sensor 26 has an abnormality such as a failure for some reason, the actual fuel pressure in the low-pressure delivery pipe 25 becomes unknown, so that the discharge capacity of the feed pump 22 can be appropriately controlled. There was a problem that it was impossible. As a fail safe in this case, for example, in order to prevent engine stall due to insufficient fuel pressure, the fuel pressure is excessively increased. However, in this case, the feed pump 22 is unnecessarily driven, and fuel consumption is deteriorated due to unnecessary wasted driving energy. Further, when the feed pump 22 uses a motor with a brush as a drive source, the life of the brush may be reduced due to wear. Furthermore, when the fuel pressure is high, the allowable maximum current value of the built-in motor of the feed pump 22 becomes high, which leads to an increase in cost and size of the FPC 28.

  Therefore, in the present embodiment, the ECU 50 determines whether or not the fuel pressure sensor 26 is abnormal based on the detection result detected by the fuel pressure sensor 26, and performs drive control of the feed pump 22 based on the determination result. It is supposed to switch.

  Specifically, when the fuel pressure sensor 26 is not abnormal, that is, is normal, the ECU 50 controls the feed pump 22 via the FPC 28 so that the actual fuel pressure detected by the fuel pressure sensor 26 becomes the target fuel pressure as described above. The drive is feedback controlled.

  On the other hand, when the fuel pressure sensor 26 is abnormal, the ECU 50 estimates the fuel pressure based on the drive current of the feed pump 22 and drives the feed pump 22 via the FPC 28 so that the estimated fuel pressure becomes the target fuel pressure. Feedback control is provided. The ECU 50 and the FPC 28 for switching the drive control of the feed pump 22 constitute a pump drive control unit according to the present invention. Further, the ECU 50 that determines whether or not the fuel pressure sensor 26 is abnormal constitutes an abnormality determination unit according to the present invention.

  Here, specifically, whether or not the fuel pressure sensor 26 is abnormal is determined by the ECU 50 as follows.

  That is, the ECU 50 estimates the fuel pressure based on the drive current of the feed pump 22 and detects it by the fuel pressure sensor 26 when the air-fuel ratio of the exhaust gas discharged from the engine 10 is not a predetermined air-fuel ratio. When the measured fuel pressure deviates from the estimated fuel pressure, it is determined that the fuel pressure sensor 26 is abnormal.

  The predetermined air / fuel ratio determined in advance is, for example, a theoretical air / fuel ratio. Therefore, when the air-fuel ratio of the exhaust gas is not a predetermined air-fuel ratio, the air-fuel ratio detected by the A / F sensor 65 is either richer or leaner than the stoichiometric air-fuel ratio. Refers to cases. For example, when the fuel pressure detected by the fuel pressure sensor 26 is higher than the actual fuel pressure due to a failure of the fuel pressure sensor 26 or the like, a large amount of fuel is injected into the engine 10 and the exhaust gas becomes rich. That is, it can be assumed that an abnormality has occurred in the fuel pressure sensor 26 by detecting such a rich state of the exhaust gas. Therefore, it is possible to detect the abnormality of the fuel pressure sensor 26 at an early stage by performing the abnormality determination process of the fuel pressure sensor 26 in such a case.

  Here, there is a relationship as shown in FIG. 2 between the fuel pressure in the low-pressure delivery pipe 25 and the drive current of the feed pump 22.

That is, as shown in FIG. 2, when the applied voltage of the feed pump 22 is constant (for example, V ₁ [V]), the drive current of the feed pump 22 is, for example, fuel pressures P ₁ , P ₂ , P ₃ [ It varies with I ₁ , I ₂ , and I ₃ [A] according to kPa]. Therefore, in the present embodiment, the ECU 50 estimates the fuel pressure in the low-pressure delivery pipe 25 from the characteristics shown in FIG. The characteristics shown in FIG. 2 are experimentally obtained in advance and stored in the ROM of the ECU 50 as a map.

  Next, the drive control of the feed pump 22 will be described with reference to FIG.

  The drive control of the feed pump 22 shown in FIG. 3 is executed by the ECU 50 at predetermined time intervals.

  First, the ECU 50 calculates a target fuel pressure based on the operation state of the vehicle and the engine 10 and a requested operation input from the driver (step S1), and executes a fuel pressure sensor abnormality determination process (step S2). The fuel pressure sensor abnormality determination process will be described later.

  Next, the ECU 50 determines whether or not the fuel pressure sensor 26 is abnormal as a result of the fuel pressure sensor abnormality determination process (step S3). When it is determined that the fuel pressure sensor 26 is not abnormal, the ECU 50 measures the actual fuel pressure in the low-pressure delivery pipe 25 via the fuel pressure sensor 26 (step S4).

  Thereafter, the ECU 50 determines whether or not the target fuel pressure and the actual fuel pressure match (step S5). Here, it is not limited to the case where the target fuel pressure and the actual fuel pressure coincide with each other. For example, it may be determined whether the deviation between the target fuel pressure and the actual fuel pressure is within an allowable range.

  When the ECU 50 determines that the target fuel pressure and the actual fuel pressure do not match, the ECU 50 calculates the applied voltage of the feed pump 22 according to the deviation between these fuel pressures so that the actual fuel pressure matches the target fuel pressure ( In step S6), the feed pump 22 is driven via the FPC 28 with the calculated applied voltage (step S7).

  On the other hand, if the ECU 50 determines that the target fuel pressure and the actual fuel pressure match, the ECU 50 stores the actual fuel pressure, applied voltage, and drive current values (step S8), and proceeds to step S6. In this step, the ECU 50 learns “applied voltage-driving current characteristics” for each detected actual fuel pressure by storing each value of the actual fuel pressure, applied voltage, and driving current. The “applied voltage-driving current characteristic” learned here is reflected in the characteristic shown in FIG. As a result, it is possible to estimate the fuel pressure with higher accuracy, taking into account the effects of individual differences such as the built-in motor of the feed pump 22, the harness connected to the built-in motor, or the FPC 28, and the effects of aging.

  On the other hand, if the ECU 50 determines in step S3 that the fuel pressure sensor 26 is abnormal, the ECU 50 acquires drive current information of the feed pump 22 from the FPC 28 (step S9).

  Next, the ECU 50 estimates the fuel pressure in the low-pressure delivery pipe 25 based on the acquired drive current value by referring to the characteristics shown in FIG. 2 (step S10), and proceeds to step S6. At this time, in step S6, the ECU 50 calculates the applied voltage of the feed pump 22 according to the deviation between these fuel pressures so that the estimated fuel pressure matches the target fuel pressure, and the calculated applied voltage via the FPC 28. The feed pump 22 is driven (step S7).

  Next, the fuel pressure sensor abnormality determination process executed in step S2 of FIG. 3 will be described with reference to FIG.

  The fuel pressure sensor abnormality determination process shown in FIG. 4 is executed by the ECU 50 every time the process proceeds to step S2 in the drive control of the feed pump 22 shown in FIG.

  First, the ECU 50 acquires A / F sensor information, that is, the detection result (actual air-fuel ratio) of the A / F sensor 65 from the A / F sensor 65 (step S21).

  Next, the ECU 50 determines whether or not the air-fuel ratio (A / F) of the exhaust gas is abnormal by comparing the acquired actual air-fuel ratio with the theoretical air-fuel ratio (step S22). Specifically, the ECU 50 determines whether the air-fuel ratio detected by the A / F sensor 65 is either richer or leaner than the stoichiometric air-fuel ratio.

  When the ECU 50 determines that the air-fuel ratio (A / F) of the exhaust gas is not abnormal, that is, the acquired actual air-fuel ratio matches the theoretical air-fuel ratio, the ECU 50 determines that the fuel pressure sensor 26 is normal (step S23). ), This process is terminated.

  On the other hand, when it is determined that the air-fuel ratio (A / F) of the exhaust gas is abnormal, the fuel pressure in the low-pressure delivery pipe 25 is measured via the fuel pressure sensor 26 (step S24). Next, the ECU 50 acquires drive current information of the feed pump 22 from the FPC 28 (step S25).

  Then, the ECU 50 estimates the fuel pressure in the low-pressure delivery pipe 25 based on the acquired drive current value by referring to the characteristics shown in FIG. 2 (step S26).

  Next, the ECU 50 compares the fuel pressure measured in step S24 (hereinafter also referred to as measured fuel pressure) with the fuel pressure estimated in step S26 (hereinafter also referred to as estimated fuel pressure), and determines whether or not these fuel pressures substantially match. Determination is made (step S27).

  If the ECU 50 determines that the measured fuel pressure and the estimated fuel pressure are substantially the same, the ECU 50 determines that the fuel pressure sensor 26 is normal (step S23), and ends this process.

  On the other hand, when the ECU 50 determines that the measured fuel pressure and the estimated fuel pressure do not substantially match, that is, the measured fuel pressure deviates from the estimated fuel pressure, the ECU 50 determines that the fuel pressure sensor 26 is abnormal (step S28). The process ends.

  By the way, in step S10 of FIG. 3 and step S26 of FIG. 4 described above, fuel pressure estimation processing is performed. If any abnormality occurs in the fuel pressure estimation processing itself, an accurate estimated fuel pressure is obtained. As a result, there is a possibility that the feed pump 22 cannot be driven with an appropriate fuel pressure.

  Therefore, the ECU 50 according to the present embodiment estimates the fuel pressure in the low-pressure delivery pipe 25 based on the drive current when the fuel pressure sensor 26 is not abnormal, and estimates when the estimated fuel pressure deviates from the measured fuel pressure. Feedback control relating to driving of the feed pump 22 using fuel pressure is prohibited. That is, the ECU 50 executes an abnormality determination process for determining whether or not the fuel pressure estimation process is abnormal when the fuel pressure sensor 26 is normal, and prohibits the feedback control described above when the estimation process is abnormal.

  Hereinafter, the abnormality determination process will be specifically described with reference to a flowchart shown in FIG.

  As shown in FIG. 5, the ECU 50 determines whether or not the fuel pressure sensor 26 is abnormal (step S31), and performs an abnormality determination process after step S32 when it is determined that the fuel pressure sensor 26 is not abnormal, that is, normal. Run. On the other hand, when the ECU 50 determines that the fuel pressure sensor 26 is abnormal, the ECU 50 ends this process.

  Here, whether or not the fuel pressure sensor 26 is abnormal is determined by a fuel pressure sensor abnormality determination process shown in FIG. At this time, in the fuel pressure sensor abnormality determination process shown in FIG. 4, when the fuel pressure sensor 26 is normal because the air-fuel ratio (A / F) of the exhaust gas is normal, the abnormality determination process after step S32 is executed. Is preferred. If the abnormality determination process shown in FIG. 5 is executed when the fuel pressure sensor is determined to be normal by the processes of step S24 to step S27 shown in FIG. 4, this abnormality determination process even if the estimated fuel pressure is not normal. This is because it may be determined in step S36 that the measured fuel pressure and the estimated fuel pressure are substantially the same.

  If the ECU 50 determines in step S31 that the fuel pressure sensor 26 is not abnormal, that is, is normal, the ECU 50 measures the fuel pressure in the low-pressure delivery pipe 25 via the fuel pressure sensor 26 (step S32).

  Next, the ECU 50 acquires drive current information of the feed pump 22 from the FPC 28 (step S34).

  Then, the ECU 50 estimates the fuel pressure in the low-pressure delivery pipe 25 based on the acquired drive current value by referring to the characteristics shown in FIG. 2 (step S35).

  Next, the ECU 50 compares the measured fuel pressure measured in step S32 with the estimated fuel pressure estimated in step S35, and determines whether or not these fuel pressures substantially match (step S36).

  If the ECU 50 determines that the measured fuel pressure and the estimated fuel pressure are substantially the same, the ECU 50 ends the process assuming that the fuel pressure estimation process is normal.

  On the other hand, when the ECU 50 determines that the measured fuel pressure and the estimated fuel pressure do not substantially match, that is, the estimated fuel pressure deviates from the measured fuel pressure, the ECU 50 prohibits feedback control related to driving of the feed pump 22 by the estimated fuel pressure. (Step S38), this process is terminated.

  Here, for example, if there is a contact failure of the connector that electrically connects the built-in motor of the feed pump 22 and the FPC 28, an energization abnormality that increases the wiring resistance may occur. Such abnormal energization of the feed pump 22 is a factor that hinders normal operation of the built-in motor of the feed pump 22. For this reason, it is necessary to detect abnormally energization of the feed pump 22 at an early stage and to take countermeasures.

  Therefore, in the present embodiment, by using the characteristics shown in FIG. 2, the energization abnormality detection process for detecting the energization abnormality of the feed pump 22 as described above is executed. This energization abnormality detection process is executed by the ECU 50 according to the flowchart shown in FIG. The energization abnormality detection process shown in FIG. 6 is executed at predetermined time intervals.

  As shown in FIG. 6, the ECU 50 measures the fuel pressure in the low-pressure delivery pipe 25 via the fuel pressure sensor 26 (step S41).

  Thereafter, the ECU 50 calculates an applied voltage of the feed pump 22 based on the measured measured fuel pressure, and sends an instruction value of the calculated applied voltage to the FPC 28 to give an applied voltage instruction (step S42). Then, the ECU 50 acquires drive current information of the feed pump 22 from the FPC 28 (step S43).

Next, the ECU 50 refers to the normal range information of the applied voltage from the acquired drive current value (step S44). Here, the normal range information of the applied voltage is a range of the applied voltage required to obtain a predetermined fuel pressure when the driving current is constant. For example, the upper limit applied voltage is V _H and the lower limit applied voltage. Is information indicating a range where _VL is V _L. A plurality of normal range information is provided for each value of the drive current. The plurality of normal range information is experimentally obtained in advance and stored in the ROM of the ECU 50.

  Then, as a result of referring to the normal range information stored in the ROM in step S44, the ECU 50 determines whether or not the actual applied voltage value obtained from the FPC 28 is within the normal range described above (step S45).

  If the ECU 50 determines that the actual applied voltage value is within the normal range described above, the value of the applied voltage instructed in step S42 and the actual applied voltage value are substantially the same. It is determined that the energized state is normal, and this process is terminated.

  On the other hand, if the ECU 50 determines that the actual applied voltage value is not within the above-described normal range, the actual applied voltage value greatly deviates from the applied voltage value instructed in step S42. This process is terminated when an energization abnormality of the pump 22 is detected.

For example, as shown in FIG. 7, the fuel pressure measured in step S41 is P ₁ [kPa], and the applied voltage V ₁ [in step S42 is used as the applied voltage required to obtain the fuel pressure P ₁ [kPa]. When V] is instructed, it is assumed that the value of the drive current obtained in step S43 is I ₁ [A].

At this time, as can be determined from FIG. 7, the applied voltage required to obtain the fuel pressure P ₁ [kPa] when the drive current I ₁ [A] is constant is the applied voltage V ₁ [V]. However, the actual applied voltage obtained from the FPC 28 was the applied voltage V ₂ [V]. In this case, the applied voltage clearly deviates from the normal range including the applied voltage V ₁ [V], and it is determined that the applied voltage is excessively increased due to the energization abnormality of the feed pump 22. That is, as shown in FIG. 8, the actual applied voltage has been in the vicinity of the applied voltage V ₁ [V] included in the normal range until then, but the upper limit applied voltage V _H [V] at a certain time due to the energization abnormality. ] And it is determined that the abnormal area has been reached. Thereby, it determines with NO in step S45, and the electricity supply abnormality of the feed pump 22 is detected. FIG. 8 shows the transition of the applied voltage when the drive current is I ₁ [A] and the fuel pressure is P ₁ [kPa].

  As described above, the fuel supply apparatus according to the present embodiment estimates the fuel pressure based on the drive current of the feed pump 22 and detects it by the fuel pressure sensor 26 when the air-fuel ratio of the exhaust gas is not the stoichiometric air-fuel ratio. When the measured fuel pressure deviates from the estimated fuel pressure, it is determined that the fuel pressure sensor 26 is abnormal.

  Therefore, when the air-fuel ratio of the exhaust gas is not the stoichiometric air-fuel ratio, the abnormality determination process for the fuel pressure sensor 26 can be performed early on the assumption that an abnormality has occurred in the fuel pressure sensor 26. Thereby, the abnormality of the fuel pressure sensor 26 can be detected at an early stage.

  Further, since the fuel pressure sensor 26 is determined to be abnormal by comparing the estimated fuel pressure with the fuel pressure detected by the fuel pressure sensor 26, the abnormality of the fuel pressure sensor 26 can be accurately detected.

  Further, since the fuel supply apparatus according to the present embodiment estimates the fuel pressure from the characteristics of the drive current that varies according to the fuel pressure when the applied voltage of the feed pump 22 is constant, values other than the fuel pressure sensor 26 are used. The fuel pressure can be estimated accurately.

  Furthermore, when the fuel pressure sensor 26 is not abnormal and the estimated fuel pressure deviates from the actual fuel pressure detected by the fuel pressure sensor 26, the fuel supply apparatus according to the present embodiment performs the fuel pressure estimation process itself. It can be determined that some abnormality has occurred. In this case, if the estimated fuel pressure is used, the feed pump 22 cannot be driven at an appropriate fuel pressure, so that feedback control related to driving the feed pump 22 using the estimated fuel pressure is prohibited. Thereby, feedback control related to driving of the feed pump 22 using the estimated fuel pressure can be performed only when the fuel pressure estimation process is reliable.

  In the present embodiment, the engine 10 uses both in-cylinder injection that directly injects fuel into the combustion chamber 13 in the cylinder 11 and port injection that injects fuel into the intake port 11 a corresponding to the cylinder 11. However, the present invention is not limited to this, and may be an internal combustion engine that performs only port injection for injecting fuel into the intake port.

  In the present embodiment, the ECU 50 instructs the FPC 28 to apply the applied voltage of the feed pump 22 when performing drive control of the feed pump 22. The rotation speed of the built-in motor may be calculated, and the calculated rotation speed may be commanded to the FPC 28.

  As described above, the fuel supply device according to the present invention can detect an abnormality of the fuel pressure sensor early and accurately, and is a fuel supply device that injects and supplies fuel to an internal combustion engine mounted on a vehicle or the like. Useful.

10 Engine (Internal combustion engine)
20 First fuel supply device 21 Fuel tank 22 Feed pump (fuel pump)
25 Low Pressure Delivery Pipe 26 Fuel Pressure Sensor 27 Port Injection Injector 28 FPC (Pump Drive Control Unit)
30 Second fuel supply device 37 In-cylinder injector 40 Fuel pressure variable device 50 ECU (pump drive control means, abnormality determination means)
65 A / F sensor

Claims (3)

An electric fuel pump that pumps fuel stored in the fuel tank to the internal combustion engine;
A fuel pressure sensor for detecting a fuel pressure of fuel pumped to the internal combustion engine;
Abnormality determining means for determining whether or not the fuel pressure sensor is abnormal;
When the fuel pressure sensor is not abnormal, feedback control of the drive of the fuel pump is performed so that the actual fuel pressure detected by the fuel pressure sensor becomes a target fuel pressure, while the fuel pressure sensor is abnormal. A pump drive control unit that estimates the fuel pressure based on a drive current of the fuel pump and feedback-controls the drive of the fuel pump so that the estimated fuel pressure becomes the target fuel pressure;
The abnormality determination means estimates the fuel pressure based on the drive current when the air-fuel ratio of the exhaust gas discharged from the internal combustion engine is not a predetermined air-fuel ratio, and detects the fuel pressure by the fuel pressure sensor A fuel supply device that determines that the fuel pressure sensor is abnormal when the measured fuel pressure deviates from the estimated fuel pressure.   2. The fuel pressure according to claim 1, wherein the abnormality determination unit estimates the fuel pressure from characteristics of the drive current that varies in accordance with the fuel pressure when a voltage applied to the fuel pump is constant. Fuel supply device.   The pump drive control means estimates the fuel pressure based on the drive current when the fuel pressure sensor is not abnormal, and when the estimated fuel pressure deviates from the actual fuel pressure detected by the fuel pressure sensor, The fuel supply device according to claim 1, wherein the feedback control using the estimated fuel pressure is prohibited.

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