JP5022491B2 - Fuel leakage diagnostic device and fuel leakage diagnostic method for accumulator fuel injection device - Google Patents

Description

  The present invention relates to a fuel leakage diagnosis device and a fuel leakage diagnosis method for diagnosing the presence or absence of fuel leakage in an accumulator fuel injection device for a vehicle.

As a fuel injection device for a vehicle, an accumulator fuel injection in which fuel pumped from a fuel supply pump is temporarily stored in a pressure accumulator chamber (common rail) in a high pressure state, and high pressure fuel in the accumulator chamber is injected into an internal combustion engine (engine) There is a device. In this type of fuel injection device, a fuel leak diagnosis is performed in which a fuel leak is detected and the engine is stopped. For example, in the fuel leakage diagnosis device described in Patent Document 1, whether or not the target energization start timing TF of the electromagnetic valve 60 that controls the fuel discharge amount from the fuel supply pump 5 is less than a preset reference value TL. When the target energization start timing TF is less than the reference value TL, the fuel leakage is diagnosed. Further, in this fuel leakage diagnosis device, the fuel leakage degree ΔT is calculated by subtracting the target energization start timing TF from the reference value TL, and the upper limit value PL of the common rail is controlled so that the fuel leakage degree ΔT is reduced. .
Japanese Patent Laid-Open No. 5-52146 (paragraphs 41-53, FIG. 7)

  The fuel leakage diagnosis device described in Patent Document 1 has a problem when the remaining amount of fuel in the fuel tank is small. Specifically, when the remaining amount of fuel is small and the fuel level is uneven, air is mixed with the fuel pumped up from the fuel tank, making it difficult for the common rail pressure to rise and the target energization start timing TF to be early (small). Become. That is, the same phenomenon as in the burnout condition occurs. For this reason, when the remaining amount of fuel is low, it is not possible to distinguish between a fuel shortage condition and a fuel leak, and there is a possibility of misdiagnosing that a fuel leak has occurred even though no fuel leak has occurred. There is.

  An object of the present invention is to distinguish between a fuel shortage state and a fuel leakage in a fuel leakage diagnosis device for a pressure accumulation fuel injection device for a vehicle, and to improve the accuracy of the fuel leakage diagnosis.

  The present invention relates to a fuel leakage diagnosis device for diagnosing the presence or absence of fuel leakage in an accumulator fuel injection device for a vehicle. In parallel with the fuel shortage diagnosis processing, the vehicle longitudinal acceleration and lateral acceleration, and the fuel remaining amount are measured. Based on this, it is determined whether or not the liquid level behavior of the fuel is within an allowable range. If the liquid level behavior of the fuel is within the allowable range, a fuel leakage diagnosis is executed. A fuel leak diagnosis hold determination unit that temporarily holds the diagnosis, and a fuel leak diagnosis unit that executes a fuel leak diagnosis based on an instruction from the fuel leak diagnosis hold determination unit. Here, the “liquid level behavior of the fuel” is the degree of fluctuation of the fuel level, and the level fluctuation of the fuel corresponds to the acceleration of the vehicle.

  According to the present invention, whether or not the fuel level behavior (acceleration of fuel level fluctuation) is within an allowable range based on the longitudinal and lateral accelerations of the vehicle and the remaining amount of fuel in parallel with the burnout diagnosis. Determine. If the behavior of the fuel level is not within the allowable range, the fuel leak diagnosis is temporarily performed because air is mixed into the fuel sent to the common rail due to the remaining amount of fuel and the deviation of the fuel level. To hold. Accordingly, it is possible to prevent erroneous diagnosis as a fuel leak in a state where air is mixed into the fuel due to the deviation of the fuel liquid level in the absence of fuel and the common rail pressure hardly increases.

  According to the present invention, a state in which air is temporarily mixed into the fuel by turning the vehicle or the like is detected using the remaining fuel amount, the longitudinal acceleration and the lateral acceleration, and the fuel leakage diagnosis is temporarily suspended. Thereafter, when it is detected that the behavior of the fuel level is stable based on the remaining fuel amount, the longitudinal acceleration, and the lateral acceleration, the fuel leakage diagnosis is restarted. Therefore, even if air is temporarily mixed into the fuel due to turning of the vehicle or the like, it can be avoided that the fuel leakage is erroneously diagnosed, and the fuel leakage diagnosis can be executed reliably.

  Further, according to the present invention, the deviation of the fuel liquid level is calculated using the longitudinal acceleration and the lateral acceleration together with the fuel remaining amount, and it is determined whether or not air is mixed into the fuel. A sensor for measuring longitudinal acceleration and lateral acceleration is standardized in a vehicle stabilization system such as a skid prevention device which is considered to be common in the future. Therefore, according to the present embodiment, it is not necessary to separately provide a pressure sensor or the like capable of recognizing mixed air in the fuel suction port in order to determine whether or not air is mixed into the fuel, thereby reducing costs. it can.

  The fuel leak diagnosis apparatus further includes a fuel shortage diagnosis start determination unit that determines whether or not the fuel in the fuel tank has become equal to or less than a fuel shortage diagnosis start fuel amount, and the fuel leak diagnosis hold determination unit includes When the fuel shortage diagnosis start determination unit determines that the fuel in the fuel tank has become equal to or less than the fuel shortage diagnosis start fuel amount, a process for determining whether or not the fuel level behavior is within an allowable range is started. You may do it.

  When the remaining amount of fuel is low, the fuel level is biased due to the acceleration of the vehicle, and there is a high possibility that air will be mixed into the intake fuel of the high-pressure pump. By executing the processing by the diagnosis suspension determination unit, it is possible to effectively avoid the fuel leakage diagnosis when air is mixed into the fuel.

  In addition, the fuel leakage diagnosis suspension determination unit, when the liquid level behavior in the front-rear direction based on the detected value of the longitudinal acceleration of the vehicle exceeds a front-rear direction allowable threshold based on the remaining amount of fuel measured by a fuel gauge, or The fuel leak diagnosis is temporarily performed when the lateral liquid level behavior based on the detected value of the lateral acceleration of the vehicle exceeds the lateral allowable threshold value based on the remaining fuel amount measured by the fuel gauge. You may comprise so that it may hold.

  When the fuel tank has different shapes in the front-rear direction and the lateral direction, the fuel liquid level behavior characteristics also differ in the front-rear direction and the lateral direction. By determining whether or not the value exceeds the threshold value, the behavior of the fuel liquid level can be accurately evaluated.

  Further, the fuel leak diagnosis suspension determination unit determines that fuel is detected when the detected value of the longitudinal acceleration of the vehicle is less than the longitudinal acceleration stability threshold and the detected value of the lateral acceleration of the vehicle is less than the lateral acceleration stability threshold. You may comprise so that the holding | maintenance of leak diagnosis may be cancelled | released.

  In this case, when both the longitudinal acceleration and lateral acceleration are less than the longitudinal acceleration stability threshold and the lateral acceleration stability threshold, respectively, the fuel level behavior becomes sufficiently small in order to cancel the suspension of the fuel leakage diagnosis. After stabilization, the fuel leak diagnosis can be resumed.

  Another aspect of the present invention relates to a fuel leakage diagnosis method for diagnosing the presence or absence of fuel leakage in an accumulator fuel injection device for a vehicle. In parallel with the fuel shortage diagnosis process, this fuel leakage diagnosis method determines whether or not the liquid level behavior of the fuel is within an allowable range based on the longitudinal acceleration and lateral acceleration of the vehicle and the remaining amount of fuel. A fuel leakage diagnosis suspension determination step of executing a fuel leakage diagnosis if the liquid level behavior is within an allowable range, and temporarily suspending the fuel leakage diagnosis if the liquid level behavior of the fuel is outside the allowable range.

1 is a schematic configuration diagram of a pressure accumulation fuel injection device according to an embodiment of the present invention. Explanatory drawing explaining the behavior of the liquid level in a fuel tank. 1 is a functional block diagram of a fuel leakage diagnosis apparatus according to an embodiment of the present invention. The functional block diagram of a fuel leak diagnosis suspension determination part. The flowchart of the fuel leak diagnostic process which concerns on one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel tank 3 Filter 4 High pressure pump 5 Actuator 7 Common rail 8 Pressure sensor 9 Pressure adjustment valve 11 Fuel injection valve (injector)
2, 6, 10, 12, 13, 14 Piping 15 ECU
DESCRIPTION OF SYMBOLS 16 Rotational speed sensor 17 Accelerator sensor 20 Burnout diagnosis start determination part 21 Fuel leak diagnosis pending | holding determination part 22 Fuel leak diagnosis part 23 Front-back direction liquid level behavior calculation part 24 Front-rear direction allowable threshold value calculation part 25 1st front-back direction comparison part 26 Side Directional liquid surface behavior calculation unit 27 Lateral allowable threshold calculation unit 28 First horizontal direction comparison unit 29 OR circuit 30 Second front-rear direction comparison unit 31 Second horizontal direction comparison unit 32 AND circuit 33 Flip-flop 100 Fuel injection device

  FIG. 1 is a schematic configuration diagram of a pressure accumulation fuel injection device according to an embodiment of the present invention.

  This accumulator fuel injection device 100 includes a plurality of fuel injection valves (injectors) 11 attached corresponding to each cylinder of a diesel engine, a common rail 7 that accumulates high-pressure fuel supplied to these injectors 11, and a fuel tank. A high pressure pump 4 that pressurizes fuel sucked from 1 through a filter 3 to a high pressure and pumps the fuel to the common rail 7, and an electronic control unit (ECU) 15 that electronically controls the injector 11, the common rail 7, and the high pressure pump 4. ing.

  The high-pressure pump 4 is driven by an engine, for example, and sucks fuel in the fuel tank 1 through a pipe 2, a low-pressure pump (not shown) and a filter 3, and boosts the fuel to a high pressure determined based on an operating state or the like. The common rail 7 is supplied through the pipe 6. The high-pressure pump 4 has an actuator 5, and the pumping amount of fuel is controlled when a control signal from the ECU 15 is input to the actuator 5. The high pressure pump 4 is connected to a pipe 14 for returning excess fuel to the fuel tank 1.

  A pressure sensor 8 for detecting the common rail internal pressure is attached to the common rail 7. The pressure sensor 8 outputs the detected pressure detection signal to the ECU 15. The common rail 7 is provided with a pressure adjustment valve 9. The pressure regulating valve 9 returns excess fuel in the common rail 7 to the fuel tank 1 via the pipe 13 so that the common rail internal pressure does not become excessive.

  Each injector 11 is connected to the common rail 7 via the fuel pipe 10. The injector 11 injects fuel in the common rail 7 into a cylinder of the engine by opening and closing a built-in control valve (not shown). The fuel injection timing and the fuel injection amount are controlled by opening and closing the control valve, and the fuel injection pressure is controlled by the pressure in the common rail 7. Each injector 11 is connected to a pipe 12 for returning excess fuel to the fuel tank 1.

  The ECU 15 receives from the rotational speed sensor 16 and the accelerator sensor 17 detection signals of the engine rotational speed NE and the accelerator opening ACC representing the engine load, and based on the engine rotational speed NE and the accelerator opening ACC, the target fuel pressure, fuel injection Timing and fuel injection amount are calculated. The ECU 15 outputs a control signal to the high pressure pump 4 (actuator 5) and the pressure regulating valve 9 so that the actual fuel pressure detected by the pressure sensor 8 matches the target fuel pressure, and performs feedback control of the common rail pressure. Do. Further, the ECU 15 outputs a control signal to the injector 11 based on the calculated values of the fuel injection timing and the fuel injection amount, and controls the fuel injection timing and the fuel injection amount by the injector 11.

  FIG. 2 shows a state in the fuel tank 1 when there is no deviation in the fuel liquid level and when there is a deviation in the fuel liquid level in the fuel tank 1. FIG. 2A shows the fuel level when the remaining amount of fuel in the fuel tank 1 is larger than a predetermined value (fuel loss start fuel amount) or when the remaining amount of fuel in the fuel tank 1 is smaller than a predetermined value. This shows a situation in which the fuel intake port is not exposed from the fuel liquid level and air does not enter the intake fuel. FIG. 2 (b) shows a situation in which the fuel level behavior is large, the fuel inlet is exposed from the fuel level, and air is mixed into the sucked fuel when the remaining amount of fuel in the fuel tank 1 is smaller than a predetermined value. Indicates. Here, the liquid level behavior of the fuel is the degree of fluctuation of the fuel level. Therefore, the liquid level behavior of the fuel is determined by the acceleration of the vehicle. In FIG. 2, only the state in the fuel tank 1 viewed from one direction (for example, the lateral direction) is shown, but the shape of the fuel tank 1 may be different between the longitudinal direction and the lateral direction of the vehicle. If any of the lateral accelerations is large, the liquid level in the direction of large accelerations may be biased and air may be mixed into the fuel.

  In the fuel injection device 100 shown in FIG. 1, when a fuel leak occurs in the path from the fuel tank 1 to the injector 11, control is performed to detect the fuel leak and stop the engine. However, when the remaining amount of fuel becomes a predetermined value or less, if at least one of the longitudinal acceleration and the lateral acceleration of the vehicle becomes a predetermined value or more, the behavior of the fuel level increases as shown in FIG. Since the liquid level is uneven, air is mixed into the intake fuel of the high-pressure pump 4. In such a case, the actual fuel pressure at the common rail pressure cannot be increased to the target fuel pressure, or the actual fuel pressure at the common rail pressure is output to the actuator 5 of the high-pressure pump 4 for setting the actual fuel pressure to the target fuel pressure. The control signal becomes larger than the standard value. These phenomena are the same as those at the time of fuel leakage, and it is not possible to distinguish between a fuel shortage condition and a fuel leakage situation.

  Therefore, in the present invention, a fuel leakage diagnosis device that temporarily holds the fuel leakage diagnosis based on the remaining fuel amount, the longitudinal acceleration and the lateral acceleration of the vehicle is provided. Hereinafter, a fuel leakage diagnosis apparatus according to an embodiment of the present invention will be described with reference to FIGS. 3 to 5.

  FIG. 3 shows functional blocks of the fuel leakage diagnosis apparatus of the present invention. This fuel leak diagnosis apparatus includes a fuel shortage diagnosis start determination unit 20, a fuel leak diagnosis hold determination unit 21, and a fuel leak diagnosis unit 22. The burnout diagnosis start determination unit 20, the fuel leak diagnosis hold determination unit 21, and the fuel leak diagnosis unit 22 are realized by the ECU 15.

  The fuel shortage diagnosis start determination unit 20 determines whether or not the detected value of the remaining amount of fuel is equal to or less than a preset fuel shortage diagnosis start fuel amount by a fuel meter (not shown) installed in the fuel tank 1. judge. Here, the fuel shortage diagnosis start fuel amount is a threshold for determining whether or not to start the fuel shortage diagnosis, and is set in advance. The fuel leakage diagnosis hold determination unit 21 determines the vehicle longitudinal acceleration gl1 and lateral acceleration gt1 and the fuel remaining amount when the fuel shortage diagnosis start determination unit 20 determines that the remaining fuel amount is equal to or less than the fuel shortage diagnosis start fuel amount. Based on V, it is determined whether or not the fuel level behavior (acceleration of fuel level fluctuation) is within an allowable range. Diagnosis is executed, and if the fuel level behavior is outside the allowable range, the fuel leak diagnosis by the fuel leak diagnosis unit 22 is temporarily suspended. The fuel leakage diagnosis unit 22 determines whether or not the actual fuel pressure measured by the pressure sensor 8 follows the target fuel pressure calculated by the ECU 15, or the high-pressure pump 4 for setting the actual fuel pressure to the target fuel pressure. A fuel leakage diagnosis is executed depending on whether or not the discharge amount is equal to or greater than a standard value.

  FIG. 4 is a functional block diagram of the fuel leakage diagnosis hold determination unit 21.

  The fuel leakage diagnosis suspension determination unit 21 includes a front-rear direction liquid level behavior calculation unit 23, a front-rear direction allowance threshold calculation unit 24, a first front-rear direction comparison unit 25, a lateral direction liquid level behavior calculation unit 26, and a lateral direction allowance. A threshold calculation unit 27, a first lateral comparison unit 28, an OR circuit 29, a second front-rear direction comparison unit 30, a second lateral comparison unit 31, a logical product circuit 32, a flip-flop 33, It has.

  The front-rear direction liquid level behavior calculation unit 23 converts the front-rear acceleration gl1 detected by an acceleration sensor (not shown) into a fuel front-rear direction liquid level behavior (hereinafter referred to as front-rear liquid level behavior) gsl1. The front-rear liquid level behavior corresponds to the acceleration of the fuel level fluctuation in the vehicle front-rear direction. Since the liquid level behavior of the fuel follows the vehicle acceleration with a delay, the front / rear liquid level behavior gsl1 is calculated through a filter that delays the longitudinal acceleration gl1. The longitudinal acceleration gl1 may be calculated by differentiating the wheel speed.

  The front-rear direction allowable threshold value calculation unit 24 calculates the front-rear direction allowable threshold value gsl0 according to the remaining fuel amount V measured by a fuel gauge (not shown). The front-rear direction allowable threshold value gsl0 is the maximum value of the front-rear acceleration at which the fuel leakage diagnosis is permitted without air being mixed into the intake fuel due to the deviation of the fuel level in the specific fuel remaining amount V. .

  The first front-rear direction comparison unit 25 compares the front-rear liquid level behavior gsl1 with the front-rear direction allowable threshold value gsl0, and when the front-rear liquid level behavior gsl1 exceeds the front-rear direction allowable threshold value gsl0, a = “1” is set. When the front / rear liquid level behavior gsl1 is equal to or smaller than the front / rear direction allowable threshold value gsl0, a = “0” is output.

  The lateral liquid level behavior calculation unit 26 converts the lateral acceleration gt1 detected by an acceleration sensor (not shown) into a lateral liquid level behavior (hereinafter referred to as a lateral liquid level behavior) gst1 of fuel. The lateral liquid level behavior corresponds to the acceleration of the fuel liquid level fluctuation in the vehicle lateral direction. Since the liquid level behavior of the fuel follows the vehicle acceleration with a delay, the lateral liquid level behavior gst1 is calculated through a filter that delays the lateral acceleration gt1. The lateral acceleration gt1 may be calculated by the product of the yaw rate and the vehicle speed, or the product of the standard yaw rate (steering angle × vehicle speed) and the vehicle speed.

  The lateral direction allowable threshold value calculation unit 27 calculates the lateral direction allowable threshold value gst0 according to the remaining fuel amount V measured by a fuel gauge (not shown). The lateral allowable threshold value gst0 is the maximum value of the lateral acceleration at which the fuel leakage diagnosis is allowed without causing air to be mixed into the intake fuel due to the deviation of the fuel level in the specific fuel remaining amount V. .

  The first lateral direction comparison unit 28 compares the lateral liquid level behavior gst1 with the lateral direction allowable threshold value gst0, and outputs b = “1” when the lateral liquid level behavior gst1 exceeds the lateral direction allowable threshold value gst0. When the horizontal liquid level behavior gst1 is equal to or less than the horizontal allowable threshold value gst0, b = “0” is output.

  The logical sum circuit 29 calculates the logical sum of the output a of the first front-rear direction comparison unit 25 and the output b of the first horizontal direction comparison unit 28, and at least one of the output a or the output b is “1”. In this case, c = "1" is output. In this case, c = “1” is input to the setting input unit S of the flip-flop 33, and the flip-flop 33 outputs an output e = “1” indicating “satisfaction condition of fuel leakage diagnosis established”. In other words, the logical sum circuit 29 and the flip-flop 33 set “satisfaction condition for fuel leakage diagnosis satisfied” when either the longitudinal acceleration gsl1 or the lateral acceleration gst1 exceeds the longitudinal allowable threshold gsl0 or the lateral allowable threshold gst0. It functions to output the output e = “1”.

  On the other hand, the logical sum circuit 29 calculates the logical sum of the output a of the first front-rear direction comparison unit 25 and the output b of the first horizontal direction comparison unit 28, and both the output a and the output b are “0”. In some cases, c = "0" is output. In this case, c = “0” is input to the setting input unit S of the flip-flop 33, and the flip-flop 33 maintains the state of the current output e. That is, if the current output is an output e = “1” indicating that “the fuel leak diagnosis hold condition is satisfied”, e = “1” is maintained, and the current output is “the fuel leak diagnosis hold condition is not satisfied. If output e = “0” representing “”, e = “0” is maintained. That is, the logical sum circuit 29 and the flip-flop 33 have the current output e = “1” or the current output e = “1” when both the longitudinal acceleration gsl1 and the lateral acceleration gst1 are equal to or smaller than the longitudinal allowable threshold gsl0 and the lateral allowable threshold gst0, respectively. Keep “0”.

  The second longitudinal direction comparison unit 30 compares the longitudinal acceleration gl1 and the longitudinal acceleration stabilization threshold gl0, and outputs a ′ = “1” when the longitudinal acceleration gl1 is less than the longitudinal acceleration stabilization threshold gl0. When the acceleration gl1 is equal to or greater than the longitudinal acceleration stabilization threshold gl0, a ′ = “0” is output. The longitudinal acceleration stabilization threshold value gl0 is a value of the longitudinal acceleration so that the behavior of the fuel level becomes sufficiently small and stable so that air does not mix with the intake fuel, and is set in advance.

  The second lateral direction comparison unit 31 compares the lateral acceleration gt1 with the lateral acceleration stabilization threshold value gt0, and outputs b ′ = “1” when the lateral acceleration gt1 is less than the lateral acceleration stabilization threshold value gt0. When the acceleration gt1 is equal to or greater than the lateral acceleration stabilization threshold gt0, b ′ = “0” is output. The lateral acceleration stabilization threshold value gt0 is a value of the lateral acceleration at which the behavior of the fuel liquid level becomes sufficiently small and stable so that air does not mix with the intake fuel, and is set in advance.

  The logical product circuit 32 calculates a logical product of the output a ′ of the second front / rear direction comparison unit 30 and the output b ′ of the second horizontal direction comparison unit 31, and both the output a ′ and the output b ′ are “1”. If "," d = "1" is output. At this time, d = “1” is input to the reset input portion R of the flip-flop 33, and the flip-flop 33 resets the output e to “0” (“the fuel leakage diagnosis hold condition is not satisfied”).

  On the other hand, the logical product circuit 32 calculates the logical product of the output a ′ of the second front-rear direction comparison unit 30 and the output b ′ of the second horizontal direction comparison unit 31, and outputs either the output a ′ or the output b ′. When “0” is “0”, d = “0” is output. At this time, d = “0” is input to the reset input portion R of the flip-flop 33, and the flip-flop 33 maintains the output e in the current state.

  As described above, the fuel leakage diagnosis suspension determination unit 21 performs at least the case where the front-rear liquid level behavior gsl1 is larger than the front-rear direction allowable threshold gsl0 or the case where the horizontal liquid level behavior gst1 is larger than the horizontal allowable threshold gst0. In one case, e = “1” is output from the flip-flop 33 (the fuel leakage diagnosis hold condition is satisfied), and then both the longitudinal acceleration gl1 and the lateral acceleration gt1 are the longitudinal acceleration stabilization threshold gl0 and the lateral acceleration stabilization. Until it becomes smaller than the threshold value gt0, the output of e = “1” (“Fuel leakage diagnosis hold condition established”) is maintained. When both the longitudinal acceleration gl1 and the lateral acceleration gt1 are smaller than the longitudinal acceleration stabilization threshold gl0 and the lateral acceleration stabilization threshold gt0, the fuel leakage diagnosis suspension determination unit 21 outputs e = “0” (“the fuel leakage diagnosis suspension condition is not satisfied. ”).

  FIG. 5 is a flowchart of the fuel leakage diagnosis process according to an embodiment of the present invention.

  In step S10, whether or not the remaining fuel amount V measured by a fuel gauge (not shown) installed in the fuel tank 1 by the burnout diagnosis start determination unit 20 is equal to or less than the burnout diagnosis start fuel amount. to decide. If the remaining fuel amount V is larger than the fuel shortage diagnosis start fuel amount, the routine proceeds to step S30, where fuel leakage diagnosis is executed. On the other hand, if the remaining fuel amount V is equal to or less than the fuel shortage diagnosis starting fuel amount, the process proceeds to step S20 to determine whether or not to hold the fuel leakage diagnosis.

  In step S20, the process of the fuel leak diagnosis hold determination unit 21 of FIG. 4 is executed, and when the output e of the fuel leak diagnosis hold determination unit 21 is “0” (“the fuel leak diagnosis hold condition is not satisfied”), In step S30, the fuel leakage diagnosis unit 22 executes a fuel leakage diagnosis. On the other hand, when the output e of the diagnosis hold determination unit 21 is “1” (“the fuel leak diagnosis hold condition is satisfied”), the process proceeds to step S40 to temporarily hold the fuel leak diagnosis.

  According to the fuel leakage diagnosis process described above, when the fuel remaining amount V is equal to or less than the fuel shortage diagnosis start fuel amount (YES in S10), at least one of the front / rear liquid level behavior gsl1 or the horizontal liquid level behavior gst1 is permitted in the front / rear direction. If it becomes larger than the threshold value gsl0 or the lateral direction allowable threshold value gst0 (YES in S20), execution of the fuel leakage diagnosis is suspended (S40). Then, the fuel leakage diagnosis is suspended until both the longitudinal acceleration gl1 and the lateral acceleration gt1 are smaller than the longitudinal acceleration stabilization threshold gl0 and the lateral acceleration stabilization threshold gt0 (NO in S20). Accordingly, it is possible to prevent a fuel leak from being erroneously diagnosed as a state in which the common rail pressure is unlikely to increase because the fuel liquid level is biased in the absence of fuel and air is mixed into the fuel. In addition, when both longitudinal acceleration and lateral acceleration are less than the longitudinal acceleration stability threshold and lateral acceleration stability threshold, the suspension of the fuel leak diagnosis is released, so the behavior of the fuel level becomes sufficiently small and stable. After that, the fuel leak diagnosis can be resumed.

  Further, when the shape of the fuel tank 1 is different in the front-rear direction and the lateral direction, the characteristics of the liquid level behavior of the fuel are also different in the front-rear direction and the lateral direction. By determining whether or not the behavior threshold is exceeded, the behavior of the fuel liquid level can be accurately evaluated.

  With the conventional fuel leak diagnosis device, when turning the vehicle when the remaining amount of fuel is low, air can be temporarily mixed into the fuel and the same phenomenon as fuel leak can occur, making it possible to make a false diagnosis of fuel leak There is sex. When a fuel leak is diagnosed, a process for prohibiting restart of the vehicle is performed because of a fatal malfunction. On the other hand, in the present embodiment, a state in which air is temporarily mixed into the fuel due to turning of the vehicle or the like is detected using the remaining fuel amount V, the longitudinal acceleration gl1 and the lateral acceleration gs1, and the fuel leakage diagnosis is temporarily performed. Hold on to. Thereafter, when it is detected that the behavior of the fuel level is stabilized based on the remaining fuel amount V, the longitudinal acceleration gl1, and the lateral acceleration gs1, the fuel leakage diagnosis is resumed. Therefore, even if air is temporarily mixed into the fuel due to turning of the vehicle or the like, it can be avoided that the fuel leakage is erroneously diagnosed, and the fuel leakage diagnosis can be executed reliably.

  Further, in the present embodiment, the fuel liquid level deviation is calculated using the longitudinal acceleration gl1 and the lateral acceleration gs1 together with the fuel remaining amount V, and it is determined whether or not air is mixed into the fuel. A sensor that measures the longitudinal acceleration gl1 and the lateral acceleration gs1 is standardized in a vehicle stabilization system such as a skid prevention device that is considered to be common in the future. Therefore, according to the present embodiment, it is not necessary to separately provide a pressure sensor or the like capable of recognizing mixed air in the fuel suction port in order to determine whether or not air is mixed into the fuel, thereby reducing costs. it can.

Claims (6)

A fuel leakage diagnosis device for diagnosing the presence or absence of fuel leakage in an accumulator fuel injection device of a vehicle,
In parallel with the burnout diagnosis process, it is determined whether or not the liquid level behavior of the fuel is within an allowable range based on the longitudinal acceleration and lateral acceleration of the vehicle and the remaining amount of fuel. If there is a fuel leak diagnosis, the fuel leak diagnosis is temporarily suspended if the liquid level behavior of the fuel is outside the allowable range;
Based on an instruction from the fuel leakage diagnosis hold determination unit, a fuel leakage diagnosis unit that performs a fuel leakage diagnosis,
With
The fuel leakage diagnosis hold determination unit
When the liquid level behavior in the front-rear direction based on the detected value of the longitudinal acceleration of the vehicle exceeds the allowable threshold in the front-rear direction based on the remaining amount of fuel detected by the fuel gauge, or the lateral behavior based on the detected value of the lateral acceleration of the vehicle A fuel leak diagnosis apparatus that temporarily holds a fuel leak diagnosis in at least one of cases where a liquid level behavior in a direction exceeds a lateral allowable threshold value based on a fuel remaining amount detected by a fuel gauge . The fuel leakage diagnosis device according to claim 1,
A fuel shortage diagnosis start determination unit for determining whether or not the fuel in the fuel tank has become equal to or less than the fuel shortage diagnosis start fuel amount;
The fuel leak diagnosis suspension determination unit determines whether or not the fuel level behavior is within an allowable range when the fuel shortage diagnosis start determination unit determines that the fuel in the fuel tank has become equal to or less than the fuel shortage diagnosis start fuel amount. A fuel leakage diagnosis device that starts the determination process. The fuel leakage diagnosis device according to claim 1 or 2 ,
The fuel leakage diagnosis hold determination unit
A fuel leak diagnosis that releases the suspension of the fuel leak diagnosis when the detected value of the longitudinal acceleration of the vehicle is less than the longitudinal acceleration stability threshold and the detected lateral acceleration of the vehicle is less than the lateral acceleration stability threshold. apparatus. A fuel leakage diagnosis method for diagnosing the presence or absence of fuel leakage in an accumulator fuel injection device of a vehicle,
In parallel with the burnout diagnosis process, it is determined whether or not the liquid level behavior of the fuel is within an allowable range based on the longitudinal acceleration and lateral acceleration of the vehicle and the remaining amount of fuel. Including performing fuel leak diagnosis if it is present, and temporarily suspending fuel leak diagnosis if the liquid level behavior of the fuel is outside the allowable range,
When the liquid level behavior in the front-rear direction based on the detected value of the longitudinal acceleration of the vehicle exceeds the allowable threshold in the front-rear direction based on the remaining fuel amount detected by the fuel gauge, or the lateral behavior based on the detected value of the lateral acceleration of the vehicle A fuel leak diagnosis method for temporarily holding a fuel leak diagnosis in a case where the liquid level behavior in the direction exceeds a lateral allowable threshold value based on a fuel remaining amount detected by a fuel gauge . The fuel leakage diagnosis method according to claim 4, wherein
A fuel leakage diagnosis method, wherein when it is determined that the fuel in the fuel tank has become equal to or less than a fuel shortage diagnosis start fuel amount, determination processing for determining whether or not the fuel level behavior is within an allowable range is started . The fuel leak diagnosis method according to claim 4 or 5,
A fuel leak diagnosis that releases the suspension of the fuel leak diagnosis when the detected value of the longitudinal acceleration of the vehicle is less than the longitudinal acceleration stability threshold and the detected lateral acceleration of the vehicle is less than the lateral acceleration stability threshold. Way .

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