JP6208048B2 - Common rail pressure abnormality judgment device - Google Patents

Description

  The technology of the present disclosure relates to a common rail pressure abnormality determination device that determines presence or absence of a pressure abnormality in a common rail.

  2. Description of the Related Art Conventionally, a common rail type fuel injection system that injects fuel accumulated in a common rail from a fuel injection valve is known as a fuel injection system mounted on a diesel engine, for example, as in Patent Document 1. The common rail fuel injection system includes a supply pump that pumps fuel in a fuel tank to the common rail, a control valve that controls the pumping amount of fuel from the supply pump to the common rail, and a fuel pressure that is the pressure of the fuel in the common rail. And a pressure sensor for detection. In the fuel injection system, the opening degree of the control valve is feedback-controlled so that the detected value of the pressure sensor becomes a target value. The excess amount of fuel pumped to the common rail is returned to the fuel tank through a pressure relief valve attached to the common rail.

  Incidentally, in recent years, the pressure of the common rail has been increased to a pressure higher than a pressure that can be handled by a mechanical pressure relief valve that opens and closes according to the pressure in the common rail. For this reason, an electronically controlled pressure relief valve whose opening and closing is controlled according to the detection value of the pressure sensor is adopted as the pressure relief valve.

JP2013-24174A

  Since the electronically controlled pressure relief valve is controlled to open and close in accordance with the detection value of the pressure sensor, if an abnormality occurs in the detection value of the pressure sensor, a pressure abnormality in which the fuel pressure of the common rail greatly differs from the target value occurs. Therefore, there is a demand for a technique that can determine whether or not there is a pressure abnormality in the common rail with high accuracy even if an abnormality occurs in the detection value of the pressure sensor. Such a request is common even when a mechanical pressure relief valve is attached to the common rail.

  An object of the technology of the present disclosure is to provide a common rail pressure abnormality determination device capable of determining the presence or absence of a pressure abnormality in a common rail with high accuracy.

  A common rail pressure abnormality determination device that solves the above problems includes a supply pump that pumps fuel, a control valve that controls a pumping amount of the supply pump, a common rail that stores fuel pumped by the supply pump, and a common rail in the common rail. A fuel injection valve that injects fuel and a pressure sensor that detects a fuel pressure that is the pressure of the fuel in the common rail, and feedback the opening of the control valve so that the detected value of the pressure sensor becomes a target value A common rail pressure abnormality determination device that is applied to a fuel injection system to be controlled and determines whether or not there is a pressure abnormality in the common rail, the drive amount of the supply pump, the opening of the control valve, and the fuel that the supply pump pumps And the target injection amount of fuel injected by the fuel injection valve as parameters. Using the model representing the fuel pressure constructed from multivariate analysis and the acquired value of the parameter, the estimation unit for estimating the fuel pressure, and the deviation between the estimation value by the estimation unit and the target value is in an allowable range And a determination unit that performs an abnormality determination on the common rail on the condition that it is outside.

  According to the above configuration, since the temperature of the fuel is an element related to the kinematic viscosity of the fuel discharged from the supply pump, the drive amount of the supply pump, the opening of the control valve, and the temperature of the fuel are determined by the discharge amount of the supply pump. That is, it is an element related to the amount of fuel increase in the common rail. On the other hand, the target injection amount is an element related to the amount of fuel decrease in the common rail.

  For this reason, the estimated value of the fuel pressure calculated using a model including the supply pump drive amount, fuel temperature, control valve opening, and target injection amount as parameters does not depend on the detected value of the pressure sensor. Also, the accuracy with respect to the actual fuel pressure is high. By determining the presence or absence of pressure abnormality in the common rail based on the difference between the estimated value and the target value, the accuracy with respect to the determination result is increased.

In the common rail pressure abnormality determination device, it is preferable that the determination unit includes the condition that the state where the deviation is outside the allowable range continues for a predetermined time.
As in the above-described configuration, the reliability of abnormality determination based on the divergence is increased by making the condition that the divergence is outside the allowable range continues for a predetermined time.

In the common rail pressure abnormality determination device, the determination unit may include that the value of the integral term calculated in the feedback control is outside an allowable range.
The integral term is a value obtained by multiplying the integrated value of the deviation between the target value of the fuel pressure and the detected value by the integral gain. According to the above configuration, when the value of the integral term is out of the allowable range, an abnormality occurs in the detection value of the pressure sensor, and it is considered that the detection value is large or small with respect to the target value. . Therefore, not only the deviation between the estimated value and the target value but also the presence / absence of pressure abnormality is determined in consideration of the value of the integral term, thereby increasing the reliability of abnormality determination.

In the common rail pressure abnormality determination device, it is preferable that the determination unit includes the condition that a state in which the value of the integral term is outside the allowable range continues for a predetermined time.
According to the above configuration, an abnormality determination is made when the value of the integral term is not improved within a predetermined time. As a result, the reliability for abnormality determination based on the value of the integral term is further increased.

  In the common rail pressure abnormality determination device, the determination unit determines whether the fuel pressure is stable based on at least one of a battery output voltage, an engine speed, and a coolant temperature for cooling the engine. It is preferable that the condition includes that the fuel pressure is stable.

  According to the above configuration, whether or not there is a pressure abnormality in the common rail is determined when the fuel pressure in the common rail is stable. As a result, the reliability with respect to common rail abnormality determination is further increased.

It is a schematic structure figure showing the schematic structure of the fuel injection system carrying one embodiment which materialized the common rail pressure abnormality judging device in the art of this indication. It is a flowchart which shows an example of the process sequence of a 1st determination process. It is a flowchart which shows an example of the process sequence of a 2nd determination process. It is a flowchart which shows an example of the process sequence of a 3rd determination process. It is a flowchart which shows an example of the process sequence of an abnormality determination process.

With reference to FIGS. 1-5, one Embodiment of the pressure abnormality determination apparatus of the common rail in this indication is described with the determination method.
As shown in FIG. 1, a common rail fuel injection system 20 includes a fuel injection valve 22 that injects fuel in a common rail 21 to each cylinder 11 of a diesel engine 10 (hereinafter simply referred to as the engine 10). . Fuel is pumped from the supply pump 23 to the common rail 21.

  The supply pump 23 is a mechanical pump having a drive shaft to which the driving force of the engine 10 is transmitted. The supply pump 23 pressurizes the fuel in the fuel tank 24 and pumps the pressurized fuel to the common rail 21. The supply pump 23 includes a control valve 25 that controls the amount of fuel pumped from the supply pump 23 to the common rail 21 by limiting the suction amount of the supply pump 23 or the discharge amount from the supply pump 23.

  A pressure reducing valve 26 is attached to the common rail 21. The pressure reducing valve 26 reduces the pressure in the common rail 21 by returning a part of the fuel in the common rail 21 to the fuel tank 24 when the pressure reducing valve 26 is in the open state. The ECU 30 controls the opening and closing of the fuel injection valve 22, the opening degree of the control valve 25 of the supply pump 23, and the opening and closing of the pressure reducing valve 26.

The ECU 30 is mainly configured by a microcomputer having a central processing unit (CPU), a nonvolatile memory (ROM), and a volatile memory (RAM).
The ECU 30 acquires various information at a predetermined control cycle based on detection signals input from various sensors. The ECU 30 acquires a detected pressure value Pf that is a detected value of the fuel pressure that is the pressure of the fuel in the common rail 21 based on a detection signal from the pressure sensor 31. The ECU 30 acquires a fuel temperature Tf that is the temperature of the fuel flowing from the fuel tank 24 to the supply pump 23 based on the detection signal from the fuel temperature sensor 32. The ECU 30 acquires the opening A of the control valve 25 based on the detection signal from the opening sensor 33. The ECU 30 acquires the engine speed Ne from the detection signal from the speed sensor 34. The ECU 30 acquires a coolant temperature Tw that is the temperature of coolant that cools the engine 10 based on a detection signal from the coolant sensor 35. The ECU 30 acquires the accelerator opening ACC based on the detection signal from the accelerator sensor 36. The ECU 30 acquires the battery output voltage E from the detection signal from the voltage sensor 37.

  The injection control unit 40 of the ECU 30 controls driving of each fuel injection valve 22. The injection control unit 40 calculates the target injection amount Qf based on, for example, the engine speed Ne and the accelerator opening ACC. Then, the injection control unit 40 drives the fuel injection valve 22 based on the detected pressure value Pf so that fuel corresponding to the target injection amount Qf is injected from the fuel injection valve 22 selected based on the engine speed Ne.

  The opening degree control unit 41 of the ECU 30 controls the opening degree A of the control valve 25 by feedback control based on the detected pressure value Pf, thereby setting the fuel pressure in the common rail 21 to a target value tPf that is a predetermined constant value. Control. The opening control unit 41 controls the opening A of the control valve 25 to the target opening tA based on the deviation between the target value tPf and the pressure detection value Pf.

The pressure reducing valve control unit 42 of the ECU 30 controls the opening and closing of the pressure reducing valve 26, and controls the pressure reducing valve 26 to be in an open state when the detected pressure value Pf is higher than the maximum allowable value Pfmax.
The estimation unit 43 of the ECU 30 calculates a pressure estimated value Pes that is an estimated value of the fuel pressure. Since the supply pump 23 is a mechanical pump, the estimation unit 43 treats the engine speed Ne as the drive amount of the supply pump 23. The estimation unit 43 calculates the estimated pressure value Pes by substituting each value into a model having the engine speed Ne, the fuel temperature Tf, the target injection amount Qf, the opening A of the control valve 25, and these as parameters. The model is a model constructed from multivariate analysis based on the fuel pressure and various parameters obtained from the results of various experiments performed on the engine 10 and the analysis results.

  The engine speed Ne and the opening A of the control valve 25 are parameters relating to the amount of fuel pumped from the supply pump 23 to the common rail 21. The fuel temperature Tf is an element related to the kinematic viscosity of the fuel flowing into the supply pump 23, and this is also a parameter related to the amount of fuel pumped to the common rail 21. The target injection amount Qf is a parameter related to the amount of fuel decrease in the common rail 21. That is, the various parameters described above are elements related to the amount of fuel increase / decrease in the common rail 21.

  The first determination unit 44 of the ECU 30 determines whether or not there is a pressure abnormality in the common rail 21 based on the difference between the estimated pressure value Pes and the target value tPf, and sets a value indicating the determination result to the first flag F1. Execute the judgment process.

  Since the target value tPf is a predetermined constant value, the first determination unit 44 uses the pressure estimation value Pes as it is as a first determination value indicating a deviation between the pressure estimation value Pes and the target value tPf. The first determination unit 44 determines whether or not the estimated pressure value Pes is within an allowable range that is larger than the lower limit allowable value PesL and smaller than the upper limit allowable value PesH. The lower limit allowable value PesL and the upper limit allowable value PesH are values set based on the results of various experiments performed on the engine 10 in advance, and are used to determine the presence or absence of pressure abnormality in the common rail 21 based on the first determination value. Is the value of

  When the estimated pressure value Pes is within the allowable range, the first determination unit 44 resets the count value C1 of the first counter 45 that is the first time measuring unit and assumes that no pressure abnormality has occurred in the common rail 21 and The value of the 1 flag F1 is set to “0”. When the estimated pressure value Pes is outside the allowable range, the first determination unit 44 increments the count value C1 of the first counter 45. The first determination unit 44 continues to increment the count value C1 as long as the estimated pressure value Pes obtained in the subsequent control cycle is outside the allowable range. When the count value C1 exceeds the upper limit value C1max, the first determination unit 44 determines that a pressure abnormality has occurred in the common rail 21, and sets the value of the first flag F1 to “1”. In addition, the 1st time-measurement part should just be able to time the state whose pressure estimated value Pes is outside an allowable range, and is not restricted to a counter.

  The second determination unit 46 of the ECU 30 acquires the value of the integral term calculated by the opening degree control unit 41 as the second determination value I. And the 2nd determination part 46 determines the presence or absence of the pressure abnormality in the common rail 21 based on the 2nd determination value I, and performs the 2nd determination process which sets the value which shows the determination result to the 2nd flag F2.

  The second determination unit 46 determines whether or not the second determination value I is within an allowable range that is larger than the lower limit allowable value IL and smaller than the upper limit allowable value IH. The lower limit allowable value IL and the upper limit allowable value IH are values set based on the results of various experiments performed on the engine 10 in advance, and determine whether there is a pressure abnormality in the common rail 21 based on the second determination value I. It is a value for.

  When the second determination value I is within the allowable range, the second determination unit 46 resets the count value C2 of the second counter 47, which is the second time measuring unit, assuming that no pressure abnormality has occurred in the common rail 21. The value of the second flag F2 is set to “0”. When the second determination value I is outside the allowable range, the second determination unit 46 increments the count value C2 of the second counter 47. The second determination unit 46 continues to increment the count value C2 as long as the second determination value I obtained in the subsequent control cycle is outside the allowable range. Then, when the count value C2 exceeds the upper limit value C2max, the second determination unit 46 determines that a pressure abnormality has occurred in the common rail 21, and sets the value of the second flag F2 to “1”. Note that the second timekeeping unit is not limited to the counter as long as it can count the state where the second determination value I is outside the allowable range.

  The third determination unit 48 of the ECU 30 determines whether or not the operation of the ECU 30 and the fuel pressure in the common rail 21 are stable when determining whether or not there is a pressure abnormality in the common rail 21, and sets a value indicating the determination result to the first value. The third determination process set in the 3 flag F3 is executed. The third determination unit 48 performs a third determination process based on the battery output voltage E, the engine speed Ne, and the coolant temperature Tw.

  The third determination unit 48 determines whether or not the output voltage E is higher than a predetermined required voltage En. When the output voltage E is lower than the required voltage En, for example, it is assumed that the power supply to the ECU 30 is insufficient and the operation of the ECU 30 is unstable. Further, for example, the discharge amount of the supply pump 23 is unstable because the engine 10 does not start even though the driver performs the key-on operation, and accordingly, the fuel pressure in the common rail 21, that is, the fuel injection amount is reduced. It is assumed that it is unstable. The output voltage E is a value for determining whether or not the operation of the ECU 30 is stable and whether or not the fuel pressure in the common rail 21 is stable based on the state of the engine 10.

  The third determination unit 48 determines whether or not the engine speed Ne is greater than a predetermined required speed Nen. In order to stabilize the discharge amount of the supply pump 23, the supply pump 23 needs to be driven with a certain amount of drive. The engine speed Ne is a value for determining whether the fuel pressure in the common rail 21 is stable based on the drive amount of the supply pump 23.

  The third determination unit 48 determines whether or not the coolant temperature Tw is higher than the lower limit temperature TwL. When the cooling water temperature Tw is lower than the lower limit temperature TwL, the engine 10 is immediately after the cold start. At this time, the engine 10 is driven in a state where the resistance due to the viscosity of the engine oil is high. In such a situation, since the engine speed Ne is unstable, the discharge amount of the supply pump 23 tends to be unstable. That is, the coolant temperature Tw is a value for determining whether or not the fuel pressure in the common rail 21 is stable based on the drive environment of the supply pump 23.

  When the output voltage E, the engine speed Ne, the cooling water temperature Tw, or any one of these requirements is not satisfied, the third determination unit 48 is unstable in the operation of the ECU 30 or the fuel pressure in the common rail 21. As a certain value, “0” is set to the value of the third flag F3. The third determination unit 48 assumes that the operation of the ECU 30 and the pressure in the common rail 21 are stable when the above-described output voltage E, engine speed Ne, cooling water temperature Tw, and all the requirements related to these are satisfied. The value of 3 flag F3 is set to “1”.

  The abnormality determination unit 49 of the ECU 30 performs an abnormality determination process for determining whether there is a pressure abnormality in the common rail 21 based on the values of the first to third flags F1 to F3. The abnormality determination unit 49 performs a normal determination that the fuel pressure in the common rail 21 is normal when at least one of the values of the first to third flags F1 to F3 is “0”. The abnormality determination unit 49 performs abnormality determination that the fuel pressure in the common rail 21 is abnormal when all the values of the first to third flags F1 to F3 are “1”.

  When the abnormality determination is made in the abnormality determination process, the lamp driving unit 50 of the ECU 30 notifies the driver of the pressure abnormality of the common rail 21 by turning on the alarm lamp 51, for example. The lighting of the alarm lamp 51 is canceled by an operator who has performed maintenance accompanying abnormal pressure.

The estimation unit 43, the first determination unit 44, the second determination unit 46, the third determination unit 48, the abnormality determination unit 49, and the lamp drive unit 50 constitute a common rail pressure abnormality determination device.
The ECU 30 performs a protection operation when an abnormality determination is made in the abnormality determination process. The protection operation is an operation for protecting the engine 10 and the common rail 21. In the protection operation, the ECU 30 controls the opening degree of the control valve 25 through the opening degree control unit 41 to limit the amount of fuel pumped from the supply pump 23 to the common rail 21. As a result, the pressure in the common rail 21 is reduced, so that the mechanical load on the common rail 21 is reduced and the output of the engine 10 is limited.

  With reference to FIG. 2, the process procedure of the 1st determination process which the 1st determination part 44 performs is demonstrated. The first determination process is repeatedly performed every predetermined control cycle when the engine 10 is started. When the engine 10 is started, the value of the count value C1 of the first counter 45 is reset, and the value of the first flag F1 is set to “0”.

  As shown in FIG. 2, in the first step S11, the ECU 30 obtains various information including the engine speed Ne, the fuel temperature Tf, the target injection amount Qf, the opening A of the control valve 25, and the pressure detection value Pf. To do. In the next step S12, the ECU 30 calculates the estimated pressure value Pes by substituting the values acquired in step S11 into the model.

  Next, the ECU 30 determines whether or not the estimated pressure value Pes is within an allowable range (step S13). When the estimated pressure value Pes is within the allowable range (step S13: YES), the ECU 30 resets the count value C1 (step S14), and then sets the value of the first flag F1 to “0” (step S15). , The series of processes is temporarily terminated.

  On the other hand, when the estimated pressure value Pes is outside the allowable range (step S13: NO), the ECU 30 determines whether the count value C1 is larger than the upper limit value C1max after incrementing the count value C1 (step S16). (Step S17).

  When the count value C1 is equal to or less than the upper limit value C1max (step S17: NO), the ECU 30 proceeds to the process of step S15. When the count value C1 is larger than the upper limit value C1max (step S17: YES), the ECU 30 sets the value of the first flag F1 to “1” (step S18), and once ends a series of processes.

  With reference to FIG. 3, the 2nd determination process which the 2nd determination part 46 performs is demonstrated. The second determination process is repeatedly performed every predetermined control cycle when the engine 10 is started. When the engine 10 is started, the count value C2 of the second counter 47 is reset, and the value of the second flag F2 is set to “0”.

  As shown in FIG. 3, the ECU 30 acquires the value of the integral term calculated by the opening degree control unit 41 as the second determination value I in the first step S21. In the next step S22, the ECU 30 determines whether or not the second determination value I is included in the allowable range.

  When the second determination value I is within the allowable range (step S22: YES), the ECU 30 resets the count value C2 of the second counter 47 (step S23), and then sets the value of the second flag F2 to “0”. The setting is made (step S24), and a series of processing is once ended.

  On the other hand, when the second determination value I is outside the allowable range (step S22: NO), the ECU 30 increments the count value C2 of the second counter 47 (step S25), and the count value C2 is larger than the upper limit value C2max. Whether or not (step S26).

  When the count value C2 is equal to or less than the upper limit value C2max (step S26: NO), the ECU 30 proceeds to the process of step S24. When the count value C2 is larger than the upper limit value C2max (step S26: YES), the ECU 30 sets the value of the second flag F2 to “1” (step S27), and once ends a series of processes.

  With reference to FIG. 4, the 3rd determination process which the 3rd determination part 48 performs is demonstrated. The third determination process is repeated every predetermined control cycle when the engine 10 is started. When the engine 10 is started, the value of the third flag F3 is set to “0”.

  As shown in FIG. 4, in the first step S31, the ECU 30 acquires various types of information including the battery output voltage E, the engine speed Ne, and the coolant temperature Tw. In the next step S32, the ECU 30 determines whether the operation of the ECU 30 and the fuel pressure in the common rail 21 are stable based on the values acquired in step S31.

  When both the operation of the ECU 30 and the fuel pressure in the common rail 21 are stable (step S32: YES), the ECU 30 sets the value of the third flag F3 to “1” (step S33) and performs a series of processes. Exit once. When at least one of the operation of the ECU 30 and the discharge amount of the supply pump 23 is unstable (step S32: NO), the ECU 30 sets the value of the third flag F3 to “0” (step S34). Is temporarily terminated.

With reference to FIG. 5, the abnormality determination process which the abnormality determination part 49 performs is demonstrated. The abnormality determination process starts when the engine 10 is started and ends when the abnormality of the common rail 21 is determined.
As shown in FIG. 5, the ECU 30 determines whether or not the value of the first flag F1 is “1” in the first step S41. When the value of the first flag F1 is “1” (step S41: YES), the ECU 30 determines whether or not the value of the second flag F2 is “1” in the next step S42. When the value of the second flag F2 is “1” (step S42: YES), the ECU 30 determines whether or not the value of the third flag F3 is “1” in the next step S43. If the value of the third flag F3 is “1” (step S43: YES), the ECU 30 makes an abnormality determination for the common rail 21 (step S44) and ends the abnormality detection process. When an abnormality is determined for the common rail 21, the ECU 30 turns on the alarm lamp 51 and performs a protective operation.

  On the other hand, if the value of the first flag F1 is “0” (step S41: NO), if the value of the second flag F2 is “0” (step S42: NO), the value of the third flag F3 Is “0” (step S43: NO), the ECU 30 makes a normal determination on the common rail 21 (step S45), and again proceeds to the process of step S41. That is, the ECU 30 constantly monitors the presence or absence of pressure abnormality in the common rail 21.

Next, the operation of the above-described common rail pressure abnormality determination device will be described.
In the pressure abnormality determination device described above, the estimated pressure value Pes is calculated by substituting various parameters into a model constructed from the results of multivariate analysis based on the results of various experiments. The presence or absence of pressure abnormality in the common rail 21 is determined based on the first determination value based on the estimated pressure value Pes, in the present embodiment, on the estimated pressure value Pes itself.

  The various parameters are parameters related to the amount of fuel pumped to the common rail 21 or parameters related to the amount of fuel decrease in the common rail 21. Thus, in the model, elements related to the amount of increase / decrease in fuel in the common rail 21 are set as parameters. Therefore, the estimated pressure value Pes does not depend on the detected pressure value Pf, and the accuracy with respect to the actual fuel pressure is high. By determining the presence or absence of pressure abnormality in the common rail 21 based on the estimated pressure value Pes, the accuracy of the determination result is increased.

  In addition, the condition for determining abnormality based on the estimated pressure value Pes includes that the estimated pressure value Pes is outside the allowable range for a predetermined time. That is, when the estimated pressure value Pes is not improved within the predetermined time, an abnormality is determined based on the estimated pressure value Pes. Thereby, the reliability with respect to the abnormality determination based on the pressure estimated value Pes increases.

  The pressure abnormality determination device determines whether or not there is a pressure abnormality in the common rail 21 based on the second determination value I, that is, the value of the integral term obtained in the calculation process of the feedback control of the control valve 25. The integral term is obtained by multiplying the integrated value of the deviation between the target value tPf and the pressure detection value Pf by the integral gain. Therefore, if an abnormality occurs in the pressure sensor 31, a negative or positive deviation continues to occur between the target value tPf and the pressure detection value Pf, and the deviation is accumulated over time, so that the integral term The absolute value increases. By determining whether or not there is a pressure abnormality in the common rail 21 based on the second determination value I that is the value of the integral term having such characteristics, the reliability of the abnormality determination of the common rail 21 is increased.

  In addition, the condition for making the abnormality determination based on the second determination value I includes that the state where the second determination value I is outside the allowable range continues for a predetermined time. That is, an abnormality determination based on the second determination value I is made when the value of the second determination value I is not improved within the predetermined time. Thereby, the reliability with respect to the abnormality determination based on the 2nd determination value I increases.

  In the third determination process, the pressure abnormality determination device determines the operation of the ECU 30, the discharge amount of the supply pump 23, and whether these are stable. The pressure abnormality determination device performs abnormality determination on the common rail 21 when abnormality determination is made in the first determination processing and the second determination processing, and it is determined that the operation of the ECU 30 and the discharge amount of the supply pump 23 are stable. Confirm the decision. That is, the operation of the ECU 30 is stable and the reliability with respect to various calculation results is high, the discharge amount of the supply pump 23 is stable, and the fuel pressure in the common rail 21 is stable. When it is satisfied, the abnormality determination for the common rail 21 is confirmed. As a result, since the accuracy of the pressure estimated value Pes is increased, the reliability with respect to the abnormality determination of the common rail 21 is further increased.

According to the above embodiment, the effects listed below can be obtained.
(1) A model including elements related to the amount of increase / decrease in fuel of the common rail 21 as a parameter is constructed, and the estimated pressure value Pes is calculated based on this model. As a result, the accuracy with respect to the determination result based on the estimated pressure value Pes increases.

(2) The abnormality determination condition includes a state in which the estimated pressure value Pes is outside the allowable range. As a result, the reliability with respect to the abnormality determination based on the pressure estimated value Pes is increased.
(3) The abnormality determination condition includes that the second determination value I, which is the value of the integral term based on the deviation between the target value tPf and the pressure detection value Pf, is outside the allowable range. As a result, the reliability with respect to the abnormality determination of the common rail 21 is further increased.

(4) The abnormality determination condition includes a state in which the second determination value I is outside the allowable range. As a result, the reliability with respect to the abnormality determination based on the second determination value I is increased.
(5) The condition for abnormality determination includes the operation of the ECU 30 and the stability of the discharge amount of the supply pump 23. As a result, the reliability with respect to the abnormality determination of the common rail 21 is increased.

  (6) The pressure detection value Pf is constantly monitored by the first determination value and the second determination value I. Therefore, even if the pressure detection value Pf of the pressure sensor 31 is gradually shifted, it is possible to detect an abnormality of the pressure sensor 31 based on the first determination value and the second determination value I.

  (7) As another method for determining the presence or absence of pressure abnormality in the common rail 21, a plurality of pressure sensors whose detection of power supply system and pressure are completely independent are attached to the common rail 21. There is a method of determining the presence or absence of pressure abnormality based on the detection value of the pressure sensor after confirming the certainty of the detection value based on the detection value of the plurality of pressure sensors. However, when such a method is embodied, the configuration of the entire system becomes complicated due to, for example, wiring and software configurations. In this respect, the pressure abnormality determination device does not require a pressure sensor other than the pressure sensor 31 to be provided on the common rail 21, and parameters required for the determination are parameters used for other controls such as fuel injection, for example. Therefore, the configuration of the entire apparatus is simplified.

  (8) According to the above configuration, when an abnormality is determined for the common rail 21, a protection operation is performed to limit the amount of fuel pumped to the common rail 21. As a result, an excessive increase in fuel pressure can be suppressed regardless of the pressure relief valve including the electronic control type and the mechanical type.

(9) Further, since a mechanical pressure relief valve is not required, piping and the like connected to the pressure relief valve are not required, so that the fuel injection system can be simplified and the cost can be reduced.
In addition, the said embodiment can also be suitably changed and implemented as follows.
The third determination unit 48 may set the value of the third flag F3 based on at least one of the battery output voltage E, the engine speed Ne, and the coolant temperature Tw.

  -The 3rd determination part 48 should just set the value of the 3rd flag F3 based on the element in connection with the fuel pressure in the common rail 21. FIG. Therefore, the third determination unit 48 may set the third flag F3 based on information other than the battery output voltage E, the engine speed Ne, and the coolant temperature Tw. As this information, for example, when the supply pump 23 has a plurality of control modes, the control mode, the open / close state of the pressure reducing valve 26, and other various detection values related to the operating state of the engine 10, etc.

  -The 3rd determination part 48 may be omitted. In such a configuration, when an abnormality determination is made in both the first determination process and the second determination process, the abnormality determination for the common rail 21 is finalized.

The second determination unit 46 may set the value of the second flag F2 to “1” because the second determination value I is outside the allowable range.
-The 2nd determination part 46 may be omitted. In such a configuration, the abnormality determination for the common rail 21 is determined based on the determination results of the first determination process and the third determination process.

-The 2nd determination part 46 and the 3rd determination part 48 may be omitted. In such a configuration, the abnormality determination for the common rail 21 is determined based on the determination result of the first determination process.
The first determination unit 44 may set the value of the first flag F1 to “1” because the estimated pressure value Pes is outside the allowable range.

  In the model, the parameter indicating the drive amount of the supply pump 23 may be, for example, the rotational speed of the drive shaft of the supply pump 23 instead of the engine rotational speed Ne, or the supply pump 23 is an electric type. In some cases, it may be power consumption.

  In the model, parameters other than those described above include, for example, a value indicating the open / close state of the pressure reducing valve 26, the temperature of the engine oil, the temperature of the fuel in the common rail 21, and the like. The value indicating the open / close state of the pressure reducing valve 26 is a value based on whether or not the pressure reducing valve 26 is in an open state when the pressure reducing valve 26 is an open / closed valve, and when the pressure reducing valve 26 is a valve whose opening degree can be adjusted. Is a value based on the opening, and these are set as parameters. When the temperature of the fuel in the common rail 21 is set as a parameter, the accuracy of the pressure estimated value Pes is increased by obtaining information such as kinematic viscosity for the fuel in the common rail 21.

  The ECU 30 may use the estimated pressure value Pes not only for abnormality determination with respect to the common rail 21 but also for other uses. For example, the ECU 30 may drive the fuel injection valve 22 using the pressure in the common rail 21 as the estimated pressure value Pes in the protection operation. Further, for example, the ECU 30 may open and close the pressure reducing valve 26 based on the estimated pressure value Pes in the protection operation, or may perform feedback control of the control valve 25 based on the estimated pressure value Pes.

  The target value tPf is not limited to a constant value, and may be a value calculated based on, for example, the engine speed Ne and the target injection amount Qf. In this case, the first determination unit 44 calculates a divergence between the estimated pressure value Pes and the target value tPf, and determines based on the calculated divergence and an allowable range set for the divergence.

  F1 ... 1st flag, F2 ... 2nd flag, F3 ... 3rd flag, 10 ... Diesel engine, 11 ... Cylinder, 20 ... Fuel injection system, 21 ... Common rail, 22 ... Fuel injection valve, 23 ... Supply pump, 24 ... Fuel tank, 25 ... Control valve, 26 ... Pressure reducing valve, 30 ... ECU, 31 ... Pressure sensor, 32 ... Fuel temperature sensor, 33 ... Opening sensor, 34 ... Revolution sensor, 35 ... Coolant temperature sensor, 36 ... Accelerator Sensor 37, voltage sensor 40, injection control unit 41 opening control unit 42 pressure reducing valve control unit 43 estimation unit 44 first determination unit 45 first counter 46 second determination Reference numeral 47: second counter 48: third determination section 49: abnormality determination section 50: lamp driving section 51: alarm lamp

Claims (5)

A supply pump that pumps fuel,
A control valve for controlling the pumping amount of the supply pump;
A common rail for storing fuel pumped by the supply pump;
A fuel injection valve for injecting fuel in the common rail;
A pressure sensor that detects a fuel pressure that is a pressure of the fuel in the common rail;
A common rail pressure abnormality determination device that determines whether or not there is a pressure abnormality in the common rail, and is applied to a fuel injection system that feedback-controls the opening of the control valve so that the detected value of the pressure sensor becomes a target value. There,
Constructed from the multivariate analysis using as parameters the drive amount of the supply pump, the opening of the control valve, the temperature of the fuel pumped by the supply pump, and the target injection amount of fuel injected by the fuel injection valve An estimation unit that estimates the fuel pressure using a model representing fuel pressure and an acquired value of the parameter;
A common rail pressure abnormality determination device comprising: a determination unit that performs abnormality determination on the common rail on the condition that a deviation between an estimated value by the estimation unit and the target value is outside an allowable range. The determination unit
The common rail pressure abnormality determination device according to claim 1, wherein the condition includes a state where the deviation is outside the allowable range for a predetermined time. The determination unit
The common rail pressure abnormality determination device according to claim 1, wherein the condition includes that an integral term value calculated in the feedback control is outside an allowable range. The determination unit
The common rail pressure abnormality determination device according to claim 3, wherein the condition includes a state in which the value of the integral term is outside the allowable range for a predetermined time. The determination unit
It is determined whether or not the fuel pressure is stable based on at least one of a battery output voltage, an engine speed, and a coolant temperature for cooling the engine, and the fuel pressure is stable. The common rail pressure abnormality determination device according to any one of claims 1 to 4, which is included in the condition.

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