JP4539503B2 - Failure diagnosis device for high pressure fuel system of engine - Google Patents

Description

  The present invention relates to a failure diagnosis device for an engine high-pressure fuel system, and more particularly to a failure diagnosis device for an engine high-pressure fuel system that increases the accuracy of failure diagnosis of the high-pressure fuel system in a direct injection fuel engine.

  In an in-vehicle direct injection fuel engine, fuel in a fuel tank is pumped by a low-pressure electromagnetic fuel pump, and this low-pressure fuel is made high by a high-pressure mechanical fuel pump. Fuel is distributed by a delivery pipe and directly injected into the combustion chamber from a fuel injection valve.

  Further, in such a direct injection fuel engine, a fuel pressure sensor as a fuel pressure detecting means for detecting the pressure of the fuel supplied to the fuel injection valve is provided in the delivery pipe, and the fuel injection valve is injected according to the operating state of the engine. A fuel injection amount control unit that calculates and controls the amount of fuel injected, a fuel discharge amount calculation unit that calculates the amount of fuel discharged from the fuel pump, and a failure diagnosis unit that performs failure diagnosis of the fuel system Some are provided with control means.

Conventionally, an engine fuel supply device having a fuel pressure control system failure determination device has been subjected to fuel pressure feedback control, and the change in the fuel change amount and the change in the fuel change amount within a set time range for a predetermined time. There is a fuel control system failure determination on condition that it has continued.
JP-A-11-190240

Also, the in-cylinder fuel control system determines whether or not the high-pressure fuel system has failed based on the integrated value of the number of engine stalls immediately after the engine is started. Some switch to a system to drive the engine.
JP 10-339202 A

Further, the high-pressure fuel system diagnostic device for a cylinder fuel injection engine includes a condition when the fuel pressure of the high-pressure fuel system does not reach a set pressure even after a predetermined time has elapsed after the engine is started, and a high-pressure fuel after the engine is started. The system system fuel pressure is determined by the lower limit value and the upper limit value, and the fuel pressure pulse width exceeds the upper limit value that cannot normally be obtained under conditions of lean air-fuel ratio. Some of them diagnose an abnormality of the high-pressure fuel system when at least one of the conditions when the operation is continued is satisfied.
JP-A-11-82134

Furthermore, the engine fuel system diagnostic device is provided with a fuel supply system when the engine rotational speed is equal to or higher than the idle rotational speed and the fuel pressure is less than the high regulation pressure within a predetermined time during the non-fuel injection period. Some diagnose the system as faulty.
JP-A-10-9028

Further, the fuel system diagnostic device for the engine performs a first diagnosis based on the fuel injection amount and the fuel discharge amount after starting the fuel pressure feedback control, and determines whether the first diagnosis is defective or the fuel discharge amount is a minimum value. Alternatively, when it is determined that the maximum value is stuck, the process proceeds to the second diagnosis based on the fuel pressure, and the second diagnosis is performed when the state where the deviation between the target fuel pressure and the actual fuel pressure exceeds a predetermined value continues for a predetermined time or more. Some diagnose the result as bad.
JP 2004-68810 A

Further, the engine fuel system diagnosis device performs a diagnosis of the fuel system based on the fuel pressure when a state where the discharge pressure of the fuel pump is higher than a set value is detected for a predetermined period or more due to the engine operating state. And when it is diagnosed that there is a possibility that the discharge pressure of the fuel pump does not become higher than the set value, the on-off valve is opened to return the fuel discharged from the fuel pump to the low pressure source, and the high pressure fuel system Some release the system fuel boost.
Japanese Patent No. 3558453

By the way, in the conventional fault diagnosis device for a high pressure fuel system of a direct injection fuel engine, when the amount of fuel pressure detected by a fuel pressure sensor attached to a delivery pipe is viewed, the high pressure fuel system System failure is being judged. However, in this case, since the failure determination only one judgment fuel pressure quantity (fuel pressure amount threshold), it is necessary to set a lower value than the fuel pressure amount obtained dropped to normal as determined fuel amount (fuel pressure amount threshold), Therefore, there is a disadvantage that the failure detection capability is lowered.

  Accordingly, an object of the present invention is to add not only the fuel pressure amount but also the fuel injection amount and the fuel discharge amount to the parameters when performing a fault diagnosis of the high pressure fuel system of the direct injection fuel engine, and a map comprising a plurality of parameters. It is an object of the present invention to provide a failure diagnosis device for a high-pressure fuel system of an engine that improves the accuracy of failure diagnosis and improves driving performance.

This invention
Fuel pressure detection means for detecting the pressure of fuel supplied to the fuel injection valve of the engine is provided,
A fuel injection amount control unit that calculates and controls a fuel injection amount injected from the fuel injection valve in accordance with an operating state of the engine;
In a failure diagnosis device for a high-pressure fuel system of an engine provided with a control means provided with a fuel discharge amount calculation unit for calculating a fuel amount discharged from a fuel pump,
The control means includes
A high-pressure fuel estimated flow rate calculation unit that calculates a high-pressure fuel estimated flow rate using a fuel injection amount calculated from the fuel injection amount control unit and a fuel discharge amount calculated from the fuel discharge amount calculation unit;
A failure diagnosis unit that performs a failure diagnosis of the high-pressure fuel system using the estimated high-pressure fuel flow calculated from the high-pressure fuel estimated flow rate calculation unit and the fuel pressure amount detected from the fuel pressure detection unit ;
The failure diagnosis unit is configured to set a region that is not a normal operation region among regions of the monitoring two-dimensional map of the high-pressure fuel system configured by the high-pressure fuel estimated flow rate and the fuel pressure amount based on the fuel discharge amount. Divided into a plurality of areas according to the determined flow rate and the determined fuel pressure amount set in stages, the divided areas are grouped according to the degree of failure, and a reference time is set for each group,
When the map value calculated from the high-pressure fuel estimated flow rate and the fuel pressure amount indicates a value included in the specific group for a set reference time or longer, it is determined that the high-pressure fuel system is faulty. Features.

  Since the failure diagnosis device for the high pressure fuel system of the engine according to the present invention uses not only the fuel pressure amount but also the fuel injection amount and the fuel discharge amount as parameters and a map composed of a plurality of parameters, the failure diagnosis accuracy Can be increased. Thus, a temporary decrease in fuel pressure, such as when the fuel pressure is reduced due to contamination (foreign matter mixed in the fuel), is not erroneously determined as a failure.

This invention realizes the purpose of improving the accuracy of fault diagnosis of a high-pressure fuel system system by adding not only the fuel pressure amount but also the fuel injection amount and the fuel discharge amount to the parameters and using a map made up of a plurality of parameters. is there.
Embodiments of the present invention will be described in detail and specifically with reference to the drawings.

  1 to 17 show an embodiment of the present invention.

  In FIG. 16, reference numeral 1 denotes an in-vehicle direct injection fuel engine (hereinafter referred to as “engine”). The engine 1 includes a cylinder block 2, a cylinder head 3, and a cylinder head cover 4 that are integrated.

  In the cylinder block 2, a piston 5 is slidably provided, and a combustion chamber 6 that cooperates with the cylinder head 3 is formed. The cylinder head 3 is provided with an intake cam shaft 7 in the intake system and an intake valve 8 driven by the intake cam shaft 7, and an exhaust cam shaft 9 is installed in the exhaust system. And an exhaust valve 10 driven by the exhaust camshaft 9 is provided.

  In the intake system of the engine 1, an air cleaner 11, an intake pipe 12 that guides intake air from the air cleaner 11 to the engine 1, a throttle body 14 having a throttle valve 13, and a surge tank 15 are integrated into the cylinder head 3. The intake manifold 16 to be attached is sequentially connected.

  On the other hand, in the exhaust system of the engine 1, an exhaust manifold 17 attached to the cylinder head 3 so as to guide exhaust from the engine 1, a catalytic converter 18, and an exhaust pipe 19 are sequentially connected.

  The engine 1 is provided with a supercharger (turbocharger) 20. The supercharger 20 supercharges intake air from the air cleaner 11 side and supplies the supercharged air to the engine 1 side. The supercharger 20 includes a compressor 22 disposed in the middle of the intake pipe 12 in a supercharger case 21, a turbine 23 disposed between the exhaust manifold 17 and the catalytic converter 18, and rotated by an exhaust flow. It has. The exhaust flow to the turbine 23 is adjusted by a wastegate mechanism 25 having a wastegate valve (VSV) 24.

  The intake pipe 12 between the compressor 22 and the throttle body 14 is provided with an intercooler 26 that cools the intake air supercharged by the supercharger 20.

  The engine 1 is provided with a fuel system 27. The fuel system 27 includes a low pressure fuel system 28 and a high pressure fuel system 29.

  The low-pressure fuel system 28 is provided with an electromagnetic fuel pump 31 that is a low-pressure fuel pump in the fuel tank 30, and a pressure regulator 33 is connected to the electromagnetic fuel pump 31 via a filter 32. One end side of the low pressure side fuel supply passage 34 is connected to 33. The electromagnetic fuel pump 31 pumps the fuel in the fuel tank 30 to the engine 1 side.

  The high-pressure fuel system 29 is provided with a mechanical fuel pump 35 that is a high-pressure fuel pump at the other end of the low-pressure fuel supply passage 34. The mechanical fuel pump 35 is attached to the cylinder head 3 and is mechanically driven by the rotation of the exhaust camshaft 9 to increase the pressure of the low-pressure fuel from the electromagnetic fuel pump 31 side and pump it to the engine 1 side. A fuel return passage 36 opened in the fuel tank 30 is connected to the mechanical fuel pump 35.

  The mechanical fuel pump 35 is connected to one end side of the high-pressure side fuel supply passage 37. The other end of the high pressure side fuel supply passage 37 is connected to a delivery pipe 38 attached to the cylinder head 3. A fuel injection valve 39 attached to the cylinder head 3 is connected to the delivery pipe 38. The fuel injection valve 39 directly injects gasoline as fuel into the combustion chamber 6 in accordance with an injection pulse determined by the control means 67 described later. The fuel injection valve 39 is in communication with a fuel injection driver 40 that increases the voltage to the fuel injection valve 39.

  As shown in FIG. 17, the mechanical fuel pump 35 includes a filter 35A, a plunger 35B, a low-pressure side first one-way valve 35C, a high-pressure side second one-way valve 35D, a low-pressure pulsation damper 35E, The high pressure pulsation damper 35F and a pressure regulator 35G are included. The filter 35A filters the fuel from the low-pressure side fuel supply passage 34. The plunger 35B pressurizes and feeds the low-pressure fuel from the low-pressure side fuel supply passage 34 to a certain pressure. The first one-way valve 35C is disposed so as to bypass the plunger 35B and the second one-way valve 35D, and when the engine 1 is started (when the fuel pressure in the high-pressure side fuel supply passage 37 becomes low), the low-pressure side fuel supply passage 34 is provided. The low-pressure fuel from is directly sent to the high-pressure side fuel supply passage 37 to improve the startability of the engine 1. The second one-way valve 35D suppresses the fuel pressure drop after the engine 1 is stopped and prevents the generation of paper. The low pressure pulsation damper 35E suppresses pulsation of low pressure fuel between the filter 35A and the plunger 35B, and stabilizes the fuel pressure. The high pressure pulsation damper 35F suppresses pulsation of high pressure fuel between the plunger 35B and the second one-way valve 35D, and stabilizes the fuel pressure. The pressure regulator 35G keeps the fuel pressure at a certain amount and returns surplus fuel from the fuel return passage 36 to the fuel tank 30.

  The engine 1 is provided with an evaporated fuel control device 41. In this fuel vapor control device 41, a two-way check valve 42 is attached to the fuel tank 30, one end side of an evaporation passage 43 is connected to the two-way check valve 42, and a canister 44 is connected to the other end side of the evaporation passage 43. One end of the purge passage 45 is connected to the canister 44, the other end side of the purge passage 45 communicates with the throttle body 14 on the downstream side of the throttle valve 13, and the purge passage 45 is purged in the middle of the purge passage 45. A valve (VSV) 46 is provided.

  Further, the engine 1 is provided with an idle speed control device 47. In this idle speed control device 47, a bypass passage 48 is provided so as to bypass the throttle valve 13 and connect the inside of the throttle body 14 and the surge tank 15. An ISC valve (idle air amount control valve) 49 for adjusting the idle air amount is provided.

  Further, the engine 1 is provided with an EGR device 50. In the EGR device 50, an EGR passage 51 having one end communicating with the exhaust manifold 17 and the other end communicating with the surge tank 15 is provided, and an EGR valve 52 is provided in the middle of the EGR passage 51.

  An ignition coil 53 and a PCV valve 54 are attached to the cylinder head cover 4 of the engine 1. A tank side blow-by gas passage 55 communicating with the inside of the surge tank 15 is connected to the PCV valve 54. Further, a cleaner side blow-by gas passage 56 communicating with the air cleaner 11 is connected to the cylinder head cover 4.

  In the engine 1, a fuel pressure sensor 57 is attached to the delivery pipe 38 and detects fuel pressure (fuel pressure) to the fuel injection valve 39, and a cooling water passage 58 formed in a part of the intake manifold 16. A water temperature sensor 59 that detects the temperature of the cooling water inside and a knocking sensor 60 that detects knocking in the combustion chamber 6 are attached. The fuel pressure sensor 57 determines the fuel pressure correction value by the control means 67 described later. The water temperature sensor 59 determines the fuel injection amount by the control means 67 described later.

  The throttle body 14 is provided with a throttle sensor 61 for detecting the throttle opening of the throttle valve 13, and one end side of the pressure guiding passage 62 is connected to the downstream side of the throttle valve 13. An intake pressure sensor 63 that detects an intake pipe pressure on the downstream side of the throttle valve 13 is provided on the other end side of the pressure guide passage 62. The intake pressure sensor 63 determines the fuel injection amount by the control means 67 described later.

  An intake air temperature sensor 64 that detects the temperature of intake air is attached to the surge tank 15. The intake air temperature sensor 64 determines the intake air temperature correction value by the control means 67 described later.

  The catalytic converter 18 is provided with an oxygen sensor (O2 sensor) 65 for detecting the oxygen concentration in the exhaust gas on the upstream side.

The wastegate valve 24 , the electromagnetic fuel pump 31, the fuel injection valve driver 40, the purge valve 46, the ISC valve 49, the EGR valve 52, the ignition coil 53, the fuel pressure sensor 57, the water temperature sensor 59, the knocking sensor 60, and the throttle sensor 61 The atmospheric pressure sensor 63, the intake air temperature sensor 64, and the oxygen sensor 65 communicate with a control means (ECM) 67 that constitutes the failure diagnosis device 66 of the high-pressure fuel system 29.

  Further, a crank angle sensor 68, a battery 71 via a main switch 69 and a fuse 70, and a warning lamp 72 are in communication with the control means 67. The crank angle sensor 68 has a function of detecting the crank angle, causing the control means 67 to determine the fuel injection start timing, and detecting the engine speed, and from the mechanical fuel pump 35 based on the engine speed. The fuel discharge amount is calculated.

  The control means 67 is discharged from a fuel injection amount control unit 73 that calculates and controls the fuel injection amount injected from the fuel injection valve 39 in accordance with the operating state of the engine 1, and a mechanical fuel pump 35 as a fuel pump. And a fuel discharge amount calculation unit 74 that calculates a fuel amount to be calculated. That is, the control means 67 receives a detection signal (crank angle signal / engine speed signal) from the crank angle sensor 68, determines the fuel injection timing based on the crank angle signal, and mechanical fuel based on the engine speed signal. A fuel discharge amount (pump discharge amount) from the pump 35 is calculated, and the fuel injection valve 39 is calculated based on a detection signal from the water temperature sensor 59, an engine speed signal from the crank angle sensor 68, and a detection signal from the intake pressure sensor 63. The fuel injection amount from the intake air temperature sensor 64 is determined, the intake air temperature correction value is determined from the detection signal from the intake air temperature sensor 64, the fuel return amount is calculated from the fuel discharge amount and the fuel injection amount, and the fuel pressure sensor The fuel pressure correction value is determined by the detection signal from 57.

  Further, the control means 67 calculates the high pressure fuel estimated flow rate by using the fuel injection amount calculated from the fuel injection amount control unit 73 and the fuel discharge amount calculated from the fuel discharge amount calculation unit 74. A calculation unit 75, and a failure diagnosis unit 76 that performs a failure diagnosis of the high-pressure fuel system 29 using the high-pressure fuel estimated flow rate calculated from the high-pressure fuel estimated flow rate calculation unit 75 and the fuel pressure amount detected from the fuel pressure sensor 57; And a memory (backup RAM) 77 for storing setting data. In the high-pressure fuel estimated flow rate calculation unit 75, the calculation formula for the high-pressure fuel estimated flow rate is also a calculation formula for calculating the estimated flow rate of fuel that will pass through the pressure regulator 35G of the mechanical fuel pump 35.

  The failure diagnosis unit 76 selects a region that is not a normal operation region in a zone (region) of the monitoring two-dimensional map (see FIG. 5) of the high-pressure fuel system 29 including the high-pressure fuel estimated flow rate and the fuel pressure amount. Divided into a plurality of groups according to the fuel pressure amount (see FIG. 6), a reference time is set for each of the divided groups (see FIG. 15), and a map value calculated from the high-pressure fuel estimated flow rate and the fuel pressure amount Indicates a value included in the specific group continuously for the set reference time or more, it is determined that the high-pressure fuel system 29 is in failure.

  That is, in this embodiment, the estimated high-pressure fuel flow rate calculated by the high-pressure fuel estimated flow rate calculation unit 75 and the fuel pressure amount actually detected by the fuel pressure sensor 57, that is, not only the fuel pressure amount but also the fuel injection amount. A failure diagnosis of the high-pressure fuel system 29 is performed using a map including a plurality of parameters in addition to the fuel discharge amount.

  The conditions for determining the failure diagnosis of the high-pressure fuel system 29 include a condition that the fuel pressure sensor 57 is normal, a condition that the engine stall mode and the start mode are not being performed, and a condition that a predetermined time (XTC) has elapsed after the engine 1 is started. When all the conditions are satisfied.

  In this failure determination condition, as shown in FIG. 4, when the program is started in the control means 67 (A01), it is determined whether or not the fuel pressure sensor 57 is normal (A02), and this step A02 is NO If this step A02 is YES, it is determined whether or not the engine stall mode or the start mode is selected (A03). If this step A03 is NO, the process returns to step A02. If this step A03 is YES, it is determined whether or not a predetermined time (XTC) has elapsed since the engine 1 was started (A04). If this step A04 is NO, the process returns to step A02, and this step A04 Is YES, it is assumed that determination conditions for failure diagnosis of the high-pressure fuel system 29 are satisfied (A05).

  When the determination condition for failure diagnosis of the high-pressure fuel system 29 is established, the map of the set high-pressure fuel estimated flow rate and fuel pressure amount (see FIGS. 5 and 6) shows the set flow rate zone (flow rate region). A determination is made.

  As shown in the map of the high-pressure fuel estimated flow rate and the fuel pressure amount in FIG. 5, for the high-pressure fuel estimated flow rate, for example, determination flow rates (fuel flow rate threshold values) 1 to 4 are set. For example, determination fuel pressure amounts (fuel pressure amount threshold values) A to C are set for ˜4. And as shown in FIG. 6, the area | region which is not a normal operation area | region (normal state) is divided | segmented into a some group according to fuel pressure amount.

  As shown in FIG. 5, if the determination fuel pressure amount A is less than the determination fuel pressure amount A, the flow rate zones 1 -A to 4-A are set for the determination flow rates 1 to 4, and the determination fuel pressure amount A and the determination fuel pressure amount B are determined. The flow rate zones 1-B to 4-B are set for the flow rates 1 to 4, and between the determination fuel pressure amount B and the determination fuel pressure amount C, the flow rate zones 1-C to 4- C is set, and the flow rate zone 1 is set in the flow rate zone 1-A to the flow rate zone 1-C less than the determination flow rate 1, and the flow rate zone 2 is set between the determination flow rate 1 and the determination flow rate 2. The flow rate zone 3 is set between the determination flow rate 2 and the determination flow rate 3, and the flow rate zone 4 is set between the determination flow rate 3 and the determination flow rate 4.

  As shown in FIG. 8, when the high-pressure fuel estimated flow rate falls within the determination flow rate (time T1), the flow zone 1 to 4 is determined by determining the flow zone, and the high-pressure fuel estimated flow rate becomes the determination flow rate. Return (time T2), and when the estimated high-pressure fuel flow rate is out of the determination flow rate and the flow rate zone release delay time has elapsed (time T3), the flow rate zone determination is stopped. The flow rate zone release delay time is set for each judgment flow rate. In the determination of the flow rate zone, priority is given to the low flow rate side.

  Thus, the judgment flow rate and judgment fuel pressure amount divided into zones by the high-pressure fuel estimated flow rate and the fuel pressure amount divide the engine operating region, and the failure diagnosis is performed in the zone (region) where the fuel pressure amount is difficult to decrease. It is possible to prevent erroneous diagnosis. In particular, in a zone (region) in which the amount of fuel pressure is unlikely to decrease, a high fuel pressure amount can be set as a determination threshold value, and failure determination capability can be improved. Also, by setting the judgment fuel pressure amount stepwise (for example, judgment fuel pressure amount A to C), the degree of failure is determined, the failure judgment time is set according to the degree of failure, and the failure is detected under a wider range of conditions. Can do.

  As shown in FIG. 7, in the relationship between the high-pressure fuel estimated flow rate and the fuel pressure amount, in the flow rate zone 1, the determination flow rate <AA, corresponding to the priority (1 to 4), and in the flow rate zone 2, Flow rate <AB, corresponding to priority order (5 to 8), in flow rate zone 3, determination flow rate <AC, corresponding to priority order (9 to 12), and in flow rate zone 4, determination The flow rate <AD, which corresponds to the priority order (13 to 16).

  Further, in the relationship between the priority order and the determined fuel pressure amount, the fuel pressure amount <A1 with respect to the priority order (1), the fuel pressure amount <B1 with respect to the priority order (2), and the priority order (3). On the other hand, the fuel pressure amount <C1, normal (other than the above) with respect to the priority order (4), fuel pressure amount <A2 with respect to the priority order (5), and the priority order (6). On the other hand, the fuel pressure amount <B2, the fuel pressure amount <C2 with respect to the priority order (7), the normality (other than the above) with respect to the priority order (8), and the priority order (9). The fuel pressure amount <A3, the fuel pressure amount <B3 with respect to the priority order (10), the fuel pressure amount <C3 with respect to the priority order (11), and the priority order (12). Normal (other than the above), fuel pressure amount <A4 with respect to priority (13), and fuel pressure with respect to priority (14) <A B4, relative priority (15), a fuel pressure amount <C4, relative priority (16), is normal (other than the above).

  Further, in the failure grouping (bit allocation) for the determined fuel pressure amount, bit 0 [01H] for fuel pressure amount <A1, bit 1 [02H] for fuel pressure amount <B1, and fuel pressure amount <C1 Bit2 [04H], fuel pressure <A2 with respect to bit3 [08H], fuel pressure <B2 with bit4 [10H], and fuel pressure <C2 with bit5 [20H], bit 6 [40H] for fuel pressure <A3, bit 7 [80H] for fuel pressure <B3, bit 8 [100H] for fuel pressure <C3 For fuel pressure <A4, bit 9 [200H], for fuel pressure <B4, bit 10 [400H], and for fuel pressure <C4, bit 11 [800H].

  This failure grouping can be arbitrarily set by setting a bit in the setting address. For example, when the flow zone 1-A and the flow zone 1-B are set to the same failure group, the data is set to [03H]. Set. Further, the determination flow rate has a relationship of AA ≦ AB ≦ AC ≦ AD. The amount of fuel pressure has a relationship of A1 ≦ B1 ≦ C1, A2 ≦ B2 ≦ C2, A3 ≦ B3 ≦ C3, and A4 ≦ B4 ≦ C4. Further, the determination flow rate 1 is selected from the table of FIG. 10, and is determined to two types of AA values for the fuel discharge amount (QP) as a condition. When QP <XA (set value), the determination flow rate 1 is set to the value of AA1. When QP <XA is set, the value is set to AA2 and is selectively switched.

The high-pressure fuel estimated flow rate (QR) is calculated by the following equation. The formula for calculating the high-pressure fuel estimated flow rate (QR) is also a calculation formula for calculating the estimated flow rate of fuel that will pass through the pressure regulator 35G of the mechanical fuel pump 35.
QR = (QPP-QI) * TC
QR: High-pressure fuel estimated flow rate QPP: Fuel discharge rate (pump discharge rate)
QI: Fuel injection amount TC: Correction coefficient

  The fuel discharge amount (QPP) is set in the engine speed table of FIG. That is, the fuel discharge amount (QPP) is set to AP1 at the engine speed (NE1), set to AP2 at the engine speed (NE2), set to AP3 at the engine speed (NE3), and the engine. The rotational speed (NE4) is set to AP4.

The fuel discharge amount (QP) is calculated by the following equation.
QP = QPP * TC
QP: Fuel discharge amount QPP: Fuel discharge amount TC: Correction coefficient

The fuel injection amount (QI) is calculated by the following equation.
QI = QI '* TKP
QI: Fuel injection amount QI ': Fuel injection amount TKP: Fuel pressure correction coefficient

  The fuel pressure correction coefficient (TKP) is set in the fuel pressure amount table of FIG. As shown in FIG. 12, the fuel pressure correction coefficient (Kp1) is set for the fuel pressure amount (P1), the fuel pressure correction coefficient (Kp2) is set for the fuel pressure amount (P2), and the fuel pressure correction is set for the fuel pressure amount (P3). It is set to the coefficient (Kp3), the fuel pressure amount (P4) is set to the fuel pressure correction coefficient (Kp4), the fuel pressure amount (P5) is set to the fuel pressure correction coefficient (Kp5), and the fuel pressure amount (P6) is set to the fuel pressure The correction coefficient (Kp6) is set, the fuel pressure amount (P7) is set to the fuel pressure correction coefficient (Kp7), the fuel pressure amount (P8) is set to the fuel pressure correction coefficient (Kp8), and the fuel pressure amount (P9) is The fuel pressure correction coefficient (Kp9) is set, the fuel pressure amount (P10) is set to the fuel pressure correction coefficient (Kp10), the fuel pressure amount (P11) is set to the fuel pressure correction coefficient (Kp11), and the fuel pressure amount (P12) is set. , Fuel pressure correction coefficient (Kp12 It is set to.

  In detecting the failure determination zone, as shown in the map of FIG. 6, the flow zones are grouped into, for example, failure groups 1 to 3, and failure determination is performed according to the duration set for each failure group. .

As shown in FIG.
In the failure group 1, for example, a flow zone 2-A, a flow zone 3-A, and a flow zone 4-A are set.
The flow rate zone 2-A is bit3 [08H].
The flow rate zone 3-A is bit6 [40H].
Since the flow rate zone 4-A is assigned bit 9 [200H], GR1 = [0248H].
In the failure group 2, for example, a flow zone 3-B and a flow zone 4-B are set.
The flow rate zone 3-B is bit 7 [80H].
Since the flow rate zone 4-B is assigned bit10 [400H], GR2 = [0480H].
In the failure group 3, for example, a flow zone 2-B, a flow zone 2-C, a flow zone 3-C, and a flow zone 4-C are set.
The flow rate zone 2-B is bit4 [10H].
The flow zone 2-C is bit5 [20H].
The flow rate zone 3-C is bit8 [100H].
Since the flow rate zone 4-C is assigned bit11 [800H], GR3 = [0930H].

In measuring the duration (reference time) of the failure group, the duration of the failure group is measured while determining the flow rate zone set for the failure group. When a flow zone other than the failure group is reached, the duration is reset to zero (0).
However, for the durations of the following (a) and (b), the measurement is continued without resetting.
(A) Duration of failure group 3: Continue measurement during failure group 1 or failure group 2 (b) Duration of failure group 2: Continue measurement during failure group 1

In the failure determination, as shown in the table of FIG. 13 , the failure determination is established when the priority order is 1 and the failure group duration is TA (set value) or more, and the priority order is 2, otherwise. The failure determination is not established. This failure determination is performed for failure group 1 and failure group 2, and failure group 3 does not determine failure.

In addition, the contents of the fault monitor are stored together with the failure determination. The contents of the failure monitor are stored in the memory 77 when the failure group duration time is less than TAA (set value) to TAA or more. As shown in FIG. 9, in the failure groups 1 to 3, the contents of the failure monitor are as follows. The items in the memory 77 are the flow zone number, engine speed, intake pipe pressure, fuel pressure amount, high-pressure fuel estimated flow rate, failure monitor condition. Number of establishments. In this fault monitor storage condition, as shown in the table of FIG. 14, when the priority order is 1 and the group continuation time is less than TAA or more than TAA, the fault monitor storage condition is satisfied, and the priority order 2 In other cases, the fault monitor storage condition is not satisfied.

  The flow zone setting data and the duration determination value are shown in the table of FIG. The flow zone setting data is set by the failure grouping bit allocation shown in FIG. The failure group 1 is set to GR1, the failure group 2 is set to GR2, and the failure group 3 is set to GR3 with the bit of each flow zone set.

  FIG. 15 shows a table of setting data of each failure group, each flow zone, and determination value of duration. That is, in failure group 1, the failure determination condition is XTA1 and the failure monitor storage condition is XTM1 (set value) in GR1, and in failure group 2, the failure determination condition is XTA2 (setting value) and the failure monitor storage in GR2. The condition is XTM2, and in the failure group 3, the failure determination is not made in GR3, and the failure monitor storage condition is XTM3 (set value).

  When failure group 1 and failure group 2 are established, warning lamp 72 is lit to notify.

  Next, the operation of this embodiment will be described.

The fuel in the fuel tank 30 is supplied to the low-pressure side fuel supply passage 34 via the filter 32 by driving the electromagnetic fuel pump 31 of the low-pressure fuel system 28, and then the mechanical fuel pump 35 of the high-pressure fuel system 29. Is driven to reach the fuel injection valve 39, and is injected from the fuel injection valve 39 into the combustion chamber 6 .

  The failure diagnosis of the high-pressure fuel system 29 is performed as follows.

  First, the determination of each flow rate zone in the region that is not in the normal state of the map shown in FIG. 5 is performed as shown in FIG.

  As shown in FIG. 2, in the determination of each flow zone, when the program of the control means 67 is started (B01), it is determined whether QP <XA (B02). If this step B02 is YES, the determined flow rate is determined. 1 is AA1 (B03), and if this step B02 is NO, the determination flow rate 1 is AA2 (B04).

  Thereafter, it is determined whether or not the determination flow rate <AA (B05). If this step B05 is YES, it is determined whether or not the fuel pressure amount <A1 (B06). If this step B06 is YES, The flow rate zone 1-A is determined (B07).

  When the step B06 is NO, it is determined whether or not the fuel pressure amount is less than B1 (B08). When the step B08 is YES, the flow rate zone 1-B is determined (B09).

  When the step B08 is NO, it is determined whether or not the fuel pressure amount <C1 (B10). When the step B10 is YES, the flow rate zone 1-C is determined (B11).

  When the step B10 is NO, it is determined as normal (B12).

  If step B05 is NO, it is determined whether or not determination flow rate <AB (B13). If step B13 is YES, it is determined whether or not fuel pressure amount <A2 (B14). When B14 is YES, the flow rate zone 2-A is determined (B15).

 When the step B14 is NO, it is determined whether or not the fuel pressure amount <B2 (B16). When the step B16 is YES, the flow rate zone 2-B is determined (B17).

  When the step B16 is NO, it is determined whether or not the fuel pressure amount <C2 (B18). When the step B18 is YES, the flow rate zone 2-C is determined (B19).

  If the step B18 is NO, it is determined as normal (B20).

  When the step B13 is NO, it is determined whether or not the determination flow rate <AC (B21). When the step B21 is YES, it is determined whether or not the fuel pressure amount <A3 (B22). When B22 is YES, the flow rate zone 3-A is determined (B23).

  When the step B22 is NO, it is determined whether or not the fuel pressure amount is smaller than B3 (B24). When the step B24 is YES, the flow rate zone 3-B is determined (B25).

  When the step B24 is NO, it is determined whether or not the fuel pressure amount <C3 (B26). When the step B26 is YES, the flow rate zone 3-C is determined (B27).

  If the step B26 is NO, it is determined as normal (B28).

When the step B21 is NO, it is determined whether or not the fuel pressure amount <A4 (B29). When the step B29 is YES, the flow rate zone 4-A is determined (B30).

  When the step B29 is NO, it is determined whether or not the fuel pressure amount is smaller than B4 (B31). When the step B31 is YES, the flow rate zone 4-B is determined (B32).

  When the step B31 is NO, it is determined whether or not the fuel pressure amount <C4 (B33), and when the step B33 is YES, the flow rate zone 4-C is determined (B34).

  If the step B33 is NO, it is determined as normal (B35).

  Next, the failure group determination of the map shown in FIG. 6 is performed as shown in FIG.

As shown in FIG. 3, when the program of the control means 67 is started (C01), first, the operation region is read (C02), and it is determined whether or not it is the failure group 1 (C03).

  If this step C03 is YES, the elapsed time of failure group 1 is counted up (C04), the elapsed time of failure group 2 is counted up (C05), and the elapsed time of failure group 3 is counted up. (C06).

  If step C03 is NO, the elapsed time of failure group 1 is reset (C07), and it is determined whether or not it is failure group 2 (C08).

  If this step C08 is YES, the elapsed time of the failure group 2 is counted up (C09), and the elapsed time of the failure group 3 is counted up (C10).

  When step C08 is NO, the elapsed time of failure group 2 is reset (C11), and it is determined whether or not it is failure group 3 (C12).

  If this step C12 is YES, the elapsed time of the failure group 3 is counted up (C13).

  If step C12 is NO, the elapsed time of the failure group 3 is reset (C14).

  After the processing of steps C06, C10, C13, and C14, it is determined whether or not the elapsed time of the failure group 1 is within the determination time (C15).

  If this step C15 is YES, it is determined whether or not the elapsed time of the failure group 2 is within a predetermined time (C16).

  If this step C16 is YES, it is determined whether or not the elapsed time of the failure group 3 is within a predetermined time (C17).

  If step C17 is YES, the process returns to step C02.

Meanwhile, the step C15 is NO, it is determined that the failure group 1 failure, or to store the contents of the defect monitor failure group 1 in the memory 77 (C18). Further, the step C16 is NO, it is determined that the failure group 2 failed or stores the contents of the defect monitor failure group 2 in the memory 77 (C18). Furthermore, the step C 17 is NO, stores the contents of the defect monitor failure group 3 in the memory 77 (C18).

  Next, failure determination of the high-pressure fuel system 29 will be described based on the time chart of FIG.

  As shown in FIG. 1, for example, when the flow zone 2-B is first determined (time t1), the failure group 3 is set, and the duration of the failure group 3 starts to be measured.

  Thereafter, when the flow zone 3-B is determined (time t2), the flow zone 2-B is canceled and the failure group 3 is canceled, while the failure group 2 is set, and the duration of the failure group 2 Starts measuring.

When the duration time of the failure group 3 reaches XTM3 (time t3), the contents of the failure monitor of the failure group 3 are stored in the memory 77. Further, the flow rate zones 3-B is canceled, the failure group 2 is canceled, the duration of the duration and failure Group 3 of the failure group 2 is reset.

  Next, when the flow zone 3-B is determined (time t4), the failure group 2 is set, and the durations of the failure group 2 and the failure group 3 start to be measured.

  When the flow zone 2-A is determined (time t5), the flow zone 3-B is canceled and the failure group 2 is canceled, while the failure group 1 is set. The duration of the failure group 1 Starts measuring.

  Thereafter, when the flow rate zone 3-A is determined (time t6), the flow rate zone 2-A is canceled.

  Further, when the duration of failure group 2 reaches XTM2 (time t7), the contents of the failure monitor of failure group 2 are stored in memory 77.

When the flow rate zones 2-A is determined (time t8), the flow rate zones 3-A is Ru is canceled. Further, since the duration of the failure group 3 reaches XTM3, the contents of the failure monitor of the failure group 3 are stored in the memory 77.

  Thereafter, when the duration time of the failure group 1 reaches XTM1 (time t9), the contents of the failure monitor of the failure group 1 are stored in the memory 77.

  When the flow zone 3-B is determined (time t10), the flow zone 2-A is canceled and the failure group 1 is canceled, while the failure group 2 is set and the duration of the failure group 1 is set. Reset.

Thereafter, when the duration of the failure group 2 reaches XT A 2 (time t11), the failure of the high-pressure fuel system 29 is determined.

  When the flow zone 2-B is determined (time t12), the flow zone 3-B is canceled and the failure group 2 is canceled, while the failure group 3 is set and the duration of the failure group 2 is set. Reset.

  Thereafter, when the flow zone 2-B is canceled (time t13), the failure group 3 is canceled and the duration of the failure group 3 is reset.

  That is, in this embodiment, the high-pressure fuel estimated flow rate is calculated, and the calculated high-pressure fuel estimated flow rate is added to the parameter to determine the failure of the high-pressure fuel system 29. Specifically, by using a map of the high-pressure fuel estimated flow rate and the fuel pressure amount, the failure determination of the high-pressure fuel system 29 is divided into zones using the fuel pressure amount, the fuel injection amount, and the high-pressure fuel estimated flow rate as parameters, and the fuel pressure amount The failure diagnosis of the high-pressure fuel system 29 is performed using the determination value (classified by the engine operation ramp) divided into zones from the high-pressure fuel estimated flow rate and the fuel pressure amount. Then, by performing failure diagnosis in a zone (region) where the amount of fuel pressure is difficult to decrease, erroneous diagnosis is prevented. In the engine operation region, when the high-pressure fuel estimated flow rate is used as a parameter and divided into zones, the determination fuel pressure amount (threshold value) can be set based on a value that can be taken within the zone (region). That is, in a zone (region) in which the amount of fuel pressure is difficult to decrease, a higher determination fuel pressure amount (fuel pressure amount threshold value) can be set, thereby increasing the failure detection capability. In addition, by setting the determination fuel pressure amount in stages (for example, determination fuel pressure amounts A to C), the degree of failure is determined, and the failure determination time (reference time) according to the failure level is set. Fault detection under a wider range of conditions is possible.

  As a result, the control means 67 uses the fuel injection amount calculated from the fuel injection amount control unit 73 and the fuel discharge amount calculated from the fuel discharge amount calculation unit 74 to calculate the high pressure fuel estimated flow rate. A calculation unit 75, and a failure diagnosis unit 76 that performs a failure diagnosis of the high-pressure fuel system 29 using the high-pressure fuel estimated flow rate calculated from the high-pressure fuel estimated flow rate calculation unit 75 and the fuel pressure amount detected from the fuel pressure sensor 57; It has. Thereby, not only the fuel pressure amount but also the fuel injection amount and the fuel discharge amount are added to the parameters and the failure diagnosis is performed using the map including a plurality of parameters, so that the accuracy of the failure diagnosis can be improved. Therefore, a temporary decrease in fuel pressure, such as when the fuel pressure is reduced due to contamination (foreign matter mixed in the fuel), is not erroneously determined as a failure.

  Further, the failure diagnosis unit 76 selects a plurality of regions that are not in the normal operation region from the region of the monitoring two-dimensional map of the high-pressure fuel system 29 including the high-pressure fuel estimated flow rate and the fuel pressure amount according to the fuel pressure amount. The reference time is set for each of the divided groups, and the map value calculated from the high-pressure fuel estimated flow rate and the fuel pressure amount is continuously included in the specific group for the set reference time or longer. It is determined that the high-pressure fuel system 29 is faulty. Thereby, since the state where the high-pressure fuel system 29 is not normal is divided into a plurality of groups and a failure determination value is set for each group, it is possible to perform a highly accurate failure diagnosis control with few malfunctions, Therefore, the reliability of the system can be improved.

  In the present invention, when a variable capacity or variable fuel pressure fuel pump is used as the high-pressure fuel pump, the fuel pressure amount varies depending on the engine operating region. Therefore, the zone (region) is divided for failure diagnosis. As a result, it is possible to improve the determination accuracy of failure diagnosis.

  Adding not only the fuel pressure amount but also the fuel injection amount and the fuel discharge amount to the parameters and using a map made up of a plurality of parameters can be applied to other control devices.

It is a time chart of failure diagnosis of an engine high-pressure fuel system. It is a flowchart of flow volume determination. It is a flowchart of failure group determination. It is a flowchart of a failure determination condition. It is a map of high-pressure fuel estimated flow volume and fuel pressure amount. It is a map of the high pressure fuel estimated flow volume and fuel pressure amount which set the failure group. It is a table of the determination flow volume and determination fuel pressure amount in a flow volume zone. It is a time chart of the determination method of a flow zone. It is a table | surface of the memory content of the failure monitor of a failure group. 3 is a table of determination flow rate 1; It is a table of fuel discharge amount. It is a table of a fuel pressure correction coefficient. It is a table of failure determination. It is a table of storage conditions of a fault monitor. It is a table of flow rate zone setting data and duration determination values. 1 is a system configuration diagram of a failure diagnosis device for a high-pressure fuel system of an engine. It is a block diagram of a mechanical fuel pump.

Explanation of symbols

1 engine
66 High-pressure fuel system failure diagnosis device 27 Fuel system 28 Low-pressure fuel system 29 High-pressure fuel system 30 Fuel tank 31 Electromagnetic fuel pump 35 Mechanical fuel pump 39 Fuel injection valve 57 Fuel pressure sensor 59 Water temperature sensor 63 Intake pressure sensor 64 Intake air temperature sensor 67 Control means 68 Crank angle sensor 72 Warning light 73 Fuel injection amount control unit 74 Fuel discharge amount calculation unit 75 High pressure fuel estimated flow rate calculation unit 76 Failure diagnosis unit 77 Memory

Claims (1)

Fuel pressure detection means for detecting the pressure of fuel supplied to the fuel injection valve of the engine is provided,
A fuel injection amount control unit that calculates and controls a fuel injection amount injected from the fuel injection valve in accordance with an operating state of the engine;
In a failure diagnosis device for a high-pressure fuel system of an engine provided with a control means provided with a fuel discharge amount calculation unit for calculating a fuel amount discharged from a fuel pump,
The control means includes
A high-pressure fuel estimated flow rate calculation unit that calculates a high-pressure fuel estimated flow rate using a fuel injection amount calculated from the fuel injection amount control unit and a fuel discharge amount calculated from the fuel discharge amount calculation unit;
A failure diagnosis unit that performs a failure diagnosis of the high-pressure fuel system using the estimated high-pressure fuel flow calculated from the high-pressure fuel estimated flow rate calculation unit and the fuel pressure amount detected from the fuel pressure detection unit ;
The failure diagnosis unit is configured to set a region that is not a normal operation region among regions of the monitoring two-dimensional map of the high-pressure fuel system configured by the high-pressure fuel estimated flow rate and the fuel pressure amount based on the fuel discharge amount. Divided into a plurality of areas according to the determined flow rate and the determined fuel pressure amount set in stages, the divided areas are grouped according to the degree of failure, and a reference time is set for each group,
When the map value calculated from the high-pressure fuel estimated flow rate and the fuel pressure amount indicates a value included in the specific group for a set reference time or longer, it is determined that the high-pressure fuel system is faulty. A failure diagnosis device for a high-pressure fuel system of an engine.

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