JP2002070632A - Engine controller with failure diagnostic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability of diagnosis by separately and sequentially diagnosing failures of a fuel cutoff valve and a fuel pressure sensor in a supply pipeline system for gaseous fuel. SOLUTION: This engine controller for a gaseous fuel engine provided with the fuel cutoff valve, a fuel pressure controller, a first fuel pressure sensor detecting a fuel injection pressure, and a fuel injection valve, in this order from the upstream, has a first fuel pressure sensor diagnostic means and a fuel cutoff valve diagnostic means. The sensor diagnostic means has a first comparison means comparing a fuel pressure difference between the former and latter pressure in operation on the basis of a detection value of the sensor; a second comparison means comparing a difference between the detection value of the sensor and a fuel pressure estimation value, and a third comparison means comparing a fuel pressure correction value based on the detection value of the sensor with a prescribed value and comparing an air-fuel ratio correction value with a prescribed value. The sensor diagnostic means diagnoses a function of the sensor on the basis of the comparison results. The valve diagnostic means diagnoses a function of the fuel cutoff valve on the basis of a difference between the detection value of the sensor when the fuel cutoff valve closes and the detection valve of the sensor when the fuel cutoff valve opens, and diagnoses the function of the fuel cutoff valve after the diagnosis of the sensor function.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine control device having a failure diagnosis device, and more particularly to a failure diagnosis for performing a failure diagnosis of a fuel pressure sensor, a fuel cutoff valve, and the like provided in a fuel supply system of a gaseous fuel engine. The present invention relates to an engine control device having a device.

[0002]

2. Description of the Related Art In recent years, demands for environmental protection and economic efficiency surrounding automobiles have been steadily reinforced.
There is an increasing demand for regulation of purification of exhaust gas containing components such as HC, CO, NOx and the like discharged from the engine and for improvement of the fuel consumption rate of the engine.

[0003] On the other hand, the fuel usually used in current engines is mainly liquid fuel such as gasoline or light oil,
The reserves of the liquid fuel are limited, and there is a concern that a shortage of the supply of the liquid fuel will occur in the future and the fuel price will rise. For this reason, vehicles using alternative energy have been actively developed, and typical examples of vehicles using the alternative energy include electric vehicles and
Hybrid vehicles with liquid fuel and electricity, alcohol,
A gas vehicle using gas (natural gas, propane gas, hydrogen gas, or the like) as a fuel is exemplified.

[0004] The vehicle using the alternative energy as described above has many problems that need to be solved in terms of infrastructure such as fuel supply facilities, manufacturing costs, safety and the like. At present, among the vehicles using the alternative energy, the natural gas vehicle is one step ahead in the overall aspect including the infrastructure and the manufacturing cost, and the natural gas vehicle has However, since methane gas is a main component, it is possible to reduce the amount of exhaust gas emission as compared with a conventional liquid fuel vehicle.

[0005] Further, the fuel injection method of the engine of the natural gas vehicle is changed to a multipoint injection system (MPI) in which natural gas fuel is independently injected into each cylinder, so that the optimum air-fuel ratio control of the engine can be performed. As a result, it is possible to improve exhaust gas performance, fuel efficiency performance, power performance, drivability, etc.,
In addition, the natural gas engine uses a conventional liquid (gasoline)
The control system of the fuel engine can be diverted on a large scale, and the effect of suppressing the production cost can be expected. This natural gas vehicle meets the environmental protection requirements (exhaust gas regulations, fuel efficiency regulations, etc.) surrounding recent automobiles, which are continually being strengthened as described above, and are highly expected in the future.

Under these circumstances, in order to sufficiently satisfy the environmental protection requirements, the natural gas vehicle has been developed with respect to components related to exhaust gas performance and control technology, and has been developed to use fuel. Parts and control technologies that must be secured because they are gas have been developed. Further, there is a rapid demand for a technique for self-diagnosing the operation state and control state of the components.
In particular, a fuel which is provided in a gaseous fuel supply system and is present in a fuel pressure sensor for detecting whether the gaseous fuel is in a state suitable for fuel injection or a fuel pipe and shuts off fuel when the engine is stalled. The diagnosis of the shut-off valve is regarded as important. Conventional self-diagnosis of the fuel pressure sensor and the fuel cutoff valve generally involves checking only the state of electrical connection with a control unit that is an engine control device.

[0007]

The failure modes of the fuel pressure sensor and the fuel cutoff valve provided in the gaseous fuel supply system include the above-described mismatch of the electrical connection state (for example, disconnection of a harness or the like). In addition to the power failure, there are failure modes that cannot be determined in the electrical connection state, which affect the air-fuel ratio of the engine (emission deterioration),
There is a concern about the effect on drivability (generation of engine stall).

That is, in the fuel pressure sensor, there is an output fixing failure (intermediate potential failure) in which the characteristic is deteriorated or the output voltage is fixed to an incomplete value, and in the fuel cutoff valve, regardless of the output state of the control unit. In addition, a sticking failure (open sticking, closed sticking) in which the open / close state of the fuel cutoff valve becomes constant may be considered.

In order to diagnose these faults, usually,
The following two diagnostic methods are common. (1) Open and close the fuel cutoff valve and compare the output of the front and rear pressure sensors (diagnosis of the fuel pressure sensor). (2) The predicted fuel pressure based on the open / close signal of the fuel cutoff valve from the control unit is compared with the output of the actual fuel pressure sensor (diagnosis of the fuel cutoff valve).

However, according to the diagnostic method, when either the fuel pressure sensor or the fuel cutoff valve has failed, not only the component itself cannot be diagnosed but also the other component can be diagnosed. Finally,
According to the maintenance manual, the function of checking the function of each individual part is required. For example, with respect to the above (1) and (2), the state is as follows.

(1-1) If the fuel cutoff valve is stuck, it cannot be opened or closed, and the output of the front and rear pressure sensors becomes the same, making diagnosis impossible. (1-2) When the fuel pressure sensor performs the intermediate potential diagnosis, the output of the pressure sensor before and after the fuel cutoff valve is the same even if the fuel cutoff valve is opened and closed, and the diagnosis cannot be performed. (2-1) If the fuel cut-off valve is stuck, it cannot be opened or closed. Therefore, the expected fuel pressure based on the fuel cut-off valve open / close signal from the control unit shifts, and the comparison result with the actual fuel pressure sensor output also shifts. (2-2) When the fuel pressure sensor causes an intermediate potential failure, the output of the fuel pressure sensor becomes a specific value. Therefore, a comparison between the expected fuel pressure based on the open / close signal of the fuel cutoff valve from the control unit and the actual fuel pressure sensor output. The result shifts.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has as its object to separately order a fuel pressure sensor and a fuel cutoff valve provided in a gas fuel supply piping system. It is an object of the present invention to provide an engine control device provided with a failure diagnosis device in which the function diagnosis between the fuel pressure sensor and the fuel cut-off valve is performed to improve the reliability of the diagnosis by performing the failure diagnosis.

[0013]

In order to achieve the above object,
The engine control device including the failure diagnosis device of the present invention basically includes a fuel cutoff valve in a fuel piping system, a fuel pressure regulator for adjusting a fuel injection pressure, and a first fuel pressure sensor for detecting a fuel injection pressure. For a gaseous fuel engine provided with a fuel injection valve, wherein the failure diagnosis device includes first fuel pressure sensor diagnosis means and fuel cutoff valve diagnosis means, wherein the first fuel pressure sensor diagnosis means includes the first fuel pressure sensor diagnosis means. First comparing means for comparing the difference between the fuel pressure before and after the operation based on the detected value of the fuel pressure sensor, second comparing means for comparing the difference between the detected value of the first fuel pressure sensor and the estimated fuel pressure value, A third comparing means for comparing the fuel pressure correction value based on the detection value of the one fuel pressure sensor with a predetermined value and comparing the air-fuel ratio correction value with the predetermined value, and based on a comparison result of these comparing means, Diagnosis of the function of one fuel pressure sensor Valve diagnostic means, wherein the fuel cut-off valve diagnostic means detects the first fuel pressure sensor when the fuel cut-off valve is open and the first fuel pressure sensor when the fuel cut-off valve is closed. The function diagnosis of the fuel cutoff valve is performed based on the difference between the first fuel pressure sensor and the function diagnosis of the fuel cutoff valve is performed after the function diagnosis of the first fuel pressure sensor is performed.

[0014] In a preferred specific embodiment of the engine control device provided with the failure diagnosis device of the present invention, when the failure diagnosis device detects an abnormality in the diagnosis process, the subsequent diagnosis is prohibited. It is characterized by. Further, another preferred specific embodiment of the engine control device including the failure diagnosis device of the present invention is such that the failure diagnosis device stores a failure history, which is a diagnosis result of each diagnosis, in a memory allocated to each diagnosis. With storage means for storing,
It is connected to an external warning device such as an abnormality warning device or an external diagnosis device, and when there is a failure history, an output to the external warning device is permitted, and the failure history can be deleted by a deletion request from the external diagnosis device. It is characterized by:

The engine control device provided with the failure diagnosis device according to the present invention having the above-described structure includes a first fuel pressure sensor diagnosis means for diagnosing the function of the first fuel pressure sensor, and a first fuel pressure sensor by opening and closing the fuel cutoff valve. And a fuel cut-off valve diagnostic means for diagnosing the function of the fuel cut-off valve by comparing the output of the fuel cut-off valve. In order,
Since the failure diagnosis can be performed, the function diagnosis between the fuel pressure sensor and the fuel cutoff valve can be surely performed, and the reliability of the diagnosis can be improved. It is possible to suppress a decrease in exhaust performance and the like.

In the present invention, first, the function diagnosis of the first fuel pressure sensor is executed, and thereafter, the function diagnosis of the fuel cutoff valve is executed from the output state of the fuel pressure sensor due to the opening / closing operation of the fuel cutoff valve. In addition to the diagnosis of the fuel pressure sensor, the diagnosis of the fuel cut-off valve can be performed without fail, and the diagnosis is performed in a state where one of the valves is faulty so that the other is not erroneously diagnosed. Therefore, if an abnormality is detected in the diagnosis process, the subsequent diagnosis can be immediately prohibited.

Further, when the failure information is output to an external device, a storage means for storing a failure history, which is a diagnosis result of each diagnosis, in a memory allocated to each diagnosis is provided. Connected to an external warning device such as a device or an external diagnostic device, if there is a failure detection history, output to the external warning device is permitted, and the failure history is
Since the erasure is performed by the erasure request from the external diagnostic device, it is possible to notify the driver of the vehicle and improve serviceability in a dealer or the like.

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an engine control apparatus provided with a failure diagnosis apparatus according to an embodiment of the present invention. FIG. 1 is a configuration diagram of an entire engine system including an engine control device including the failure diagnosis device of the present embodiment.

The engine 100 is provided in each cylinder 2 thereof.
The intake pipe 4 and the exhaust pipe 5 are connected to each other. A spark plug 7 is attached to the cylinder 2, and an injector 18 is attached to the intake pipe 4. Upstream of the intake pipe 4, an air cleaner 3 and a throttle valve 2
3 and the air flow sensor 6 and the throttle sensor 21 are attached. An exhaust sensor (oxygen sensor) 20 is attached to the exhaust pipe 5, and a water temperature sensor 8 is attached to the cylinder 2.

The state information of the engine 100 includes an intake air amount detection sensor 6 for measuring a mass flow rate of air which is drawn into the cylinder 2 through the air cleaner 3 and the intake pipe 4, and a water temperature for measuring a cooling water temperature of the cylinder 2. Detection signals from a sensor 8, an intake air temperature sensor 9 for measuring an intake air temperature, a crank angle sensor (not shown) for detecting a crank angle, a throttle sensor 21 for detecting a throttle angle, and the like are input to the control unit (control device) 1. . The control unit 1 calculates the engine speed from the crank angle sensor signal, and calculates the engine load from the throttle opening, the intake air amount, and the engine speed.

The control unit 1 calculates the optimum fuel injection pulse width, fuel injection timing, ignition timing, etc. supplied to the engine 100 based on the various information, and injects fuel from the injector 18 which is a fuel injection valve. Control to do. In the ignition system, the air-fuel mixture in the combustion chamber is ignited by the ignition plug 7 by energizing / cutting off an ignition coil (not shown).

Further, the control unit 1 calculates a feedback correction value of the air-fuel ratio based on a signal from an exhaust sensor 20 for measuring the oxygen concentration in the exhaust gas discharged through the exhaust pipe 5, and calculates the air-fuel ratio feedback correction value. The fuel injection pulse width of the fuel injection valve 18 is corrected so that the air reaches the stoichiometric air-fuel ratio.

On the other hand, the gaseous fuel supply system includes a fuel cylinder 10 for filling and storing gaseous fuel in a high pressure state, a pressure regulator (regulator) 16 for adjusting fuel pressure of fuel injection, an injector 18 for injecting fuel, and a cylinder 10. Pressure regulator 16
, A low-pressure pipe 17 connecting the regulator 16 and the injector 18, and a fuel cutoff valve 1 installed on the cylinder side and the pressure regulator 16 side of the high-pressure pipe 15.
2. A fuel temperature sensor 13 installed in the low pressure pipe 17 for detecting a fuel state (fuel temperature, fuel pressure), a first fuel pressure sensor 14, and a second fuel pressure sensor 11 corresponding to a high pressure for detecting an abnormal fuel pressure in the high pressure pipe 15. Have been. Although not shown, cylinder 1
A main valve (fuel cutoff valve) and a safety valve are installed at the outlet of the high pressure pipe 0.

Next, a description will be given of an outline of control for calculating the fuel injection amount (pulse) injected from the fuel injection valve 18 of the engine control device with the failure diagnosis device of the present embodiment. The calculation of the basic fuel injection pulse uses a general gasoline pulse calculation method, calculates information on the operating state of the engine, that is, information on the amount of intake air and the number of engine revolutions, and uses that information as a basis. , The basic pulse width (the injection pulse width required for each cylinder determined from the intake air amount) is calculated. Further, the information of the exhaust sensor 20 is detected, and an air-fuel ratio correction value (for example, an air-fuel ratio feedback value or an air-fuel ratio learning value) for the stoichiometric air-fuel ratio is calculated.

Further, the control unit 1 includes a fuel temperature sensor 13 and a first fuel pressure sensor 1 in the fuel supply system.
4, a fuel temperature correction coefficient is calculated based on the relationship between the fuel and the basic fuel temperature (for example, the calculation formula: √ (input fuel temperature value) / √ (basic fuel temperature value)). (For example, the calculation formula: (base fuel pressure value) / calculation result from (input fuel pressure value)), the fuel pressure correction coefficient is calculated, and the calculation result is calculated as the pulse width correction value.

As described above, the basic pulse width calculated by the control unit (control device) 1, the air-fuel ratio correction value,
The control unit (control device) 1 calculates the final injection pulse width based on the pulse width correction value, and the injector driving circuit that is finally output to the injector 18 by the injector driving circuit based on the final injection pulse width. A signal is output.

In this embodiment, the first fuel pressure sensor 1
The self-diagnosis of the fuel cutoff valve 4 and the fuel cutoff valve 12 is performed without interference with each other. In the diagnosis, first, the diagnosis of the first fuel pressure sensor 14 is executed, and
In the case of K (no abnormality), the diagnosis of the fuel cutoff valve 12 is executed.

However, it is desirable that the diagnosis of disconnection or short-circuit, which is the confirmation of the electrical connection described in the section of the prior art, be performed independently of the implementation of the present embodiment. As a result, if a failure is clearly detected, the diagnosis according to the present embodiment may be a diagnosis control form that is omitted. In other words, the diagnosis of the present embodiment is to execute a check diagnosis of the function of a component that cannot be detected in the check diagnosis of the electrical connection. Needless to say, the diagnosis according to the embodiment is performed.

Next, a description will be given of a specific example of the failure diagnosis control of the engine control device provided with the failure diagnosis device of the present embodiment. The failure diagnosis device according to the present embodiment includes a first fuel pressure sensor 1
And a fuel cutoff valve diagnosing means for self-diagnosing the fuel cutoff valve 4 and the fuel cutoff valve 12. The first fuel pressure sensor diagnosing means further comprises a first comparing means and a second comparing means. , And third comparing means.

FIG. 2 is a control flowchart of the failure diagnosis according to the present embodiment, showing an outline of the whole failure diagnosis control, and showing a control flow of the first fuel pressure sensor diagnosis means and the fuel cutoff valve diagnosis means. Things. The control flow of this failure diagnosis is executed in a fixed time task. First, in step 20, it is a step of determining whether or not to diagnose the first fuel pressure sensor 14. Can be implemented by storing the information as ROM information in the memory of the control device 1 in advance, and if not permitted, the fault diagnosis control flow is passed. The program can be shared by storing it in advance as ROM information in the memory.

If it is permitted, the process proceeds to step 21, where a first comparison of the fuel pressure sensor 14 is performed, and the result of the comparison is confirmed. Details of the first comparison (means) are shown in a control flowchart (described later) of FIG. Step 2
In 1, if the first comparison result is OK (no abnormality), the process proceeds to step 22, where the second comparison of the fuel pressure sensor 14 is performed, and the comparison result is confirmed. Second comparison (means)
Are shown in a control flowchart (described later) of FIG.

If the second comparison result in step 22 is OK (no abnormality), the process proceeds to step 23, where the fuel pressure sensor 14
The third comparison is performed, and the comparison result is confirmed. Details of the third comparison (means) are shown in a control flowchart (described later) of FIG. If any one of the determinations in steps 21 to 23 is NG (NO), the process proceeds to step 29, where it is determined that the first fuel pressure sensor 14 is abnormal, and the present control flow ends ( If the first fuel pressure sensor 14 is abnormal, accurate diagnosis of the fuel cutoff valve 12 cannot be performed, so that the following control flow of the shutoff valve diagnosis is not performed).

Although not described in the present control flow, a step for confirming the diagnosis result of the first fuel pressure sensor 14 is provided at the beginning of the control flow, and if an abnormality occurs during the current operation of the engine (running). If (NG) is detected, this control flow can be passed.

Next, in the determinations in steps 21 to 23, if all the comparison results are OK, it is determined in step 24 that the first fuel pressure sensor 14 is normal, and the process proceeds to step 25. Fuel shutoff valve 12
Of the diagnosis is determined. In the case of permission, the process proceeds to step 26, where the diagnosis of the fuel cutoff valve 12 is performed. If the diagnosis result is OK (YES), the process proceeds to step 28.
If NG (NO), the process proceeds to step 27 to determine whether the fuel cutoff valve 12 is normal or abnormal.

Here, the normality determination processing in steps 24 and 28 means that a normality determination flag set for each diagnosis is set, and the abnormality determination processing in steps 29 and 27 is This means that an abnormality determination flag set for each diagnosis is set, and an operation state at that time, an NG code set for each diagnosis, and the like are prepared to be output as NG information to an external diagnosis device.

FIG. 3 is a control flowchart showing the contents of the first comparison of the first fuel pressure sensor 14, and it is determined whether or not the fuel pressure in the fuel pipe 17 changes due to a sudden change in the fuel supply amount. Things. First, in step 30, engine speed, load information, and the like are fetched, and in step 31, it is determined whether or not the vehicle is in an operating state in which fuel pressure changes, that is, whether or not it is in a transient state. Step 3
If it is determined in step 1 that the fuel pressure is not expected to change and it is determined that the engine is in the steady state, the control flow is terminated, and if it is determined that the engine is in the transient state, the control flow is terminated. Then, the fuel pressure information is stored and the routine proceeds to step 32. In step 32, the differential pressure of the fuel pressure before and after the change in the operating state is calculated and calculated. Therefore, the fuel pressure information needs to be temporarily stored in the memory as a past history at regular time intervals.

In step 33, it is determined whether or not the calculation result of the differential pressure before and after the change of the operating state is equal to or more than a predetermined value. When the purpose is to detect an intermediate potential failure of the fuel pressure sensor 14, the sign of the differential pressure is irrelevant. If the absolute value is equal to or more than a certain value, it is determined to be OK. If OK, an OK determination flag is set in step 35, and if NG, an NG determination flag is set in step 34 (if one flag is set, it goes without saying that the other flag is cleared). As described above, the first comparison is completed, and the determination result of OK / NG is as follows.
It will be used in step 21 of FIG.

FIG. 4 is a control flow chart showing the contents of the second comparison of the first fuel pressure sensor 14. The estimated fuel pressure value to be adjusted is compared with the actual fuel pressure.
This is to detect abnormalities in the data. First, at step 36, the reference fuel pressure of the pressure regulator 16 stored in the memory in advance is read, and at step 37, the reference fuel pressure
The injection pressure estimation value A (the fuel pressure measured by the first fuel pressure sensor 14) is estimated in consideration of the pressure adjustment variation and the like. For example, if the source pressure in the cylinder 10 is equal to or higher than the pressure adjustment value of the pressure regulator 16, the output of the first fuel pressure sensor 14 is estimated to be the pressure adjustment value ± variation. If the source pressure in the cylinder 10 is less than the pressure adjustment value of the pressure regulator 16, the output of the first fuel pressure sensor 14 is equal to the source pressure ±
It is estimated that there is variation. Incidentally, the fuel pressure (source pressure) of the cylinder 10 is measured by the second fuel pressure sensor 11.

In step 38, the actual output value B of the first fuel pressure sensor 14 is read, and in step 39, the difference between the estimated value A and the actually measured value B is calculated (in FIG. Is calculated, but it is not necessary to calculate as an absolute value.) In step 40, it is determined whether or not the difference is within the allowable value.
It is determined as K, and if it is other than the allowable value, it is determined as NG. OK
If so, the OK determination flag is set in step 42,
If it is NG, an NG determination flag is set in step 41 (if one flag is set, the other flag is cleared). With the above, the second comparison is completed, and OK / N
The determination result of G is used in step 22 of FIG.

FIG. 5 is a control flowchart showing the contents of the third comparison of the first fuel pressure sensor 14, wherein the injection pulse correction value (fuel pressure correction coefficient) from the fuel pressure information and the exhaust gas sensor 20.
And the first fuel pressure sensor 14
This is to determine the abnormality of.

First, at step 43, the exhaust sensor 20
Is determined whether or not is normal. The determination as to whether or not it is normal is made by checking the electrical connection state, output value, responsiveness, etc. If the exhaust sensor 20 is normal, the output of the first fuel pressure sensor 14 is read in step 44, In step 45, a fuel pressure correction coefficient (correction value) is calculated. The method of calculating the correction value is as described above, and is omitted here.

Next, at step 46, the exhaust sensor 20
The output of (for example, an O2 sensor) is read, and step 47
Then, an air-fuel ratio correction value is calculated based on the output value of the exhaust sensor 20. Steps 44 to 47 may be executed by a separate routine for calculating the fuel injection pulse width, instead of being executed in the flowchart of FIG.

In step 48, it is determined whether the fuel pressure correction coefficient is equal to or greater than a predetermined value. This is because, when the fuel pressure correction value is small, it is difficult to determine whether the fuel pressure correction value really matches the pressure adjustment value or whether the first fuel pressure sensor 14 has failed. If it is within the predetermined value, the control flow is ended to prevent erroneous determination.If it is not less than the predetermined value, the process proceeds to step 49, and in step 49, whether the air-fuel ratio correction value is within the predetermined value or not. Is determined. That is, when the fuel pressure correction value is an abnormal value based on the abnormality of the first fuel pressure sensor 14, the stoichiometric air-fuel ratio is excessively corrected to correct the deviation of the air-fuel ratio correction value. Because it becomes.

In step 49, it is determined whether or not the value is within the allowable value. If the value is within the allowable value, it is determined to be OK, and if it is not the allowable value, it is determined to be NG. If OK, an OK determination flag is set in step 50, and if NG, an NG determination flag is set in step 49 (if one flag is set, the other flag is cleared). Thus, the third comparison is completed, and the OK / NG determination result is used in step 23 of FIG.

As described above, the first to third comparisons are performed according to the control flow shown in FIGS. 3 to 5, and the first fuel pressure sensor 14 is diagnosed by the comparison. As a next step, the diagnosis of the fuel cutoff valve 12 described below is executed. The diagnosis of the fuel cutoff valve 12
In the control flowchart of FIG. 2, the processing after step 25 is described.
This will be described with reference to the control flowchart of FIG.

FIG. 6 is a control flow chart showing the contents of the diagnosis of the fuel cutoff valve 12.
Is operated to detect a function abnormality of the fuel cutoff valve 12 from the fuel pressure information in that state. First, in step 52, it is determined whether or not the engine 100 is rotating. This is to ensure that the fuel consumption in the pipe 17 when the shutoff valve 12 is closed is reliably performed. More specifically, the determination during the rotation of the engine may be a condition that the engine rotation speed is equal to or higher than a predetermined rotation speed. When the engine 100 is stopped,
This control flow ends. If it is determined that the engine 100 is rotating, the process proceeds to step 53.

In step 53, it is confirmed whether or not the fuel cutoff valve 12 is open. Normally, while the engine 100 is rotating, the fuel cutoff valve 12 should be open, but it is expected that the fuel cutoff valve 12 will be closed based on another control request outside the range of the present embodiment. If the valve is in a closed state in a certain situation, step 54 is performed in accordance with the priority order with other controls.
Then, the fuel cutoff valve 12 is opened, and the routine proceeds to step 55. These processes are for judging (predicting) whether or not the pipe 17 is filled with fuel. During one operation (during running), the fuel shut-off valve 1 is started at least once.
If 2 is open, this determination may be passed.

In step 55, the output of the first fuel pressure sensor 14 is read and stored as a fuel pressure value C in the memory.
In step 56, the fuel cutoff valve 12 is closed and the state is maintained for a predetermined period, and then in step 57, the output of the first fuel pressure sensor 14 is read again and stored in the memory as the fuel pressure value D. In step 58, the fuel pressure value C and the fuel pressure value D
Is calculated.

In step 59, it is determined whether or not the differential pressure is within a predetermined value. If the differential pressure is outside the allowable value, it is determined to be OK, and if it is within the allowable value, it is determined to be NG. If OK, an OK determination flag is set in step 61, and if NG, an NG determination flag is set in step 60 (if one flag is set, the other flag is cleared).

The diagnosis of the fuel cutoff valve 12 is completed according to the above control flow, and the result of the OK / NG determination is used in step 26 of FIG. 2, but steps 27 and 28 of FIG. It may be used in common with step 60. Further, in the control flow of the present diagnosis, it is determined whether or not the fuel pressure difference becomes equal to or more than a predetermined value after a predetermined period has elapsed. However, it may be determined whether or not a fuel pressure difference occurs within a predetermined period. .

The diagnosis contents of this embodiment have been described based on the control flowcharts of FIGS. 2 to 6. The important point is the order of the diagnosis. First, the diagnosis of the first fuel pressure sensor 14 is executed. After determining that the first fuel pressure sensor 14 is normal, the diagnosis of the fuel cutoff valve 12 is executed.

Further, in each of the above-mentioned diagnoses, the output of the first fuel pressure sensor 14 is used.
It is clear that the temperature changes depending on the temperature, and the fuel temperature correction based on the output from the fuel temperature sensor 13 may be performed. Next, using the control flowcharts of FIGS.
The output processing of the diagnosis result with the external diagnosis device will be described.

The control flow of FIG. 7 shows a method of outputting the result of the self-diagnosis by the external diagnostic device. The connection with the external diagnostic device is executed via communication means such as serial communication. First, in step 62, it is determined whether or not there is a request to output a result of diagnosis from the external diagnostic device. It is assumed that the operation of the diagnosis result output request is performed by an operation of a service person such as a user). If there is no output request, this routine is terminated as it is.
In step 3, the abnormality determination flag stored in the memory is read for each diagnosis item, and abnormality determination flag information (for example, code information) is output to the external diagnostic device.

The external diagnostic device converts the error code into a human-readable error code (which can be read without a conversion table for converting what is abnormal), for example, a language such as "first fuel pressure sensor error". To display on the screen. This time, the description of the abnormal code output to the external diagnostic device was described. However, from a global perspective, there are many countries where the service system is inadequate, and the external diagnostic device may not be at all levels. In such a case, it is also effective to display an abnormality by lighting or blinking a lamp in the instrument panel.

Next, a method of erasing NG information (flag) will be described with reference to the control flowchart of FIG.
The purpose of this is that, after repair by a dealer or the like, if the abnormality information (flag) of the part due to self-diagnosis remains in the memory in the control unit, the diagnosis result will not be updated unless the diagnosis is performed again, and the serviceability will be improved. This is because there is a risk of damage. It means that the abnormality information (flag) of the component is cleared by the external diagnostic device. Although it has been described above that communication with the external diagnostic device is being performed, in step 64, it is determined whether or not there is a diagnostic result erasure request from the external diagnostic device. It is assumed that the service technician who performs the deletion inputs the deletion request).

If there is no erasure request, various abnormality information (flag) is held, but if there is an erasure request, various abnormality information (flag) is erased (cleared) in step 65. As described above, one embodiment of the present invention has been described in detail, but the present invention is not limited to the above embodiment, without departing from the spirit of the invention described in the claims.
Various changes can be made in the design. For example,
In the above embodiment, the gaseous fuel is described as natural gas. However, the gaseous fuel is not limited to natural gas, and other gaseous fuels can be applied to the present invention.

[0057]

As will be understood from the above description, the engine control device provided with the failure diagnosis device of the present invention can accurately diagnose the first fuel pressure sensor and the fuel cutoff valve of the gaseous fuel supply system. In addition, operability deterioration and exhaust performance deterioration caused by erroneous self-diagnosis can be suppressed, and serviceability (operability) at the dealer can be improved.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an engine system showing an embodiment of an engine control device including a failure diagnosis device of the present invention.

FIG. 2 is a control flowchart showing diagnosis of a first fuel pressure sensor and a fuel cutoff valve according to the embodiment of FIG. 1;

FIG. 3 is a control flowchart showing a first comparison determination of a first fuel pressure sensor in the diagnosis of FIG. 2;

FIG. 4 is a control flowchart showing a second comparison determination of the first fuel pressure sensor in the diagnosis of FIG. 2;

FIG. 5 is a control flowchart showing a third comparison determination of the first fuel pressure sensor in the diagnosis of FIG. 2;

FIG. 6 is a control flowchart showing the diagnosis of the fuel cutoff valve in the diagnosis of FIG. 2;

FIG. 7 is a control flowchart of output control of a diagnosis result to the external diagnosis device according to the embodiment of FIG. 1;

FIG. 8 is a control flowchart of erasure control of the diagnostic result record of the embodiment of FIG. 1 by the external diagnostic device.

[Explanation of symbols]

 1. Control unit 2. Engine 8. Water temperature sensor 9. Intake air temperature sensor 10. Cylinder 11. Second fuel pressure sensor 12. 12. Fuel cutoff valve 13. Fuel temperature sensor First fuel pressure sensor 16, pressure regulator 18. Injector 19. External diagnostic device 20. Exhaust sensor

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme court ゛ (Reference) F02D 19/02 F02D 19/02 FZ 41/14 310 41/14 310D 310E F02M 21/02 F02M 21/02 VL (72) Inventor Masahiro Sato 2477 Takaba, Hitachinaka City, Ibaraki Prefecture Inside Hitachi Car Engineering Co., Ltd. (72) Inventor Hiroto Nishiide 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. (72) Inventor Taku Yamada 2 Takara-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Nissan Motor Co., Ltd. (72) Inventor Go Kato 6-6-1 Okada, Samukawa-cho, Koza-gun, Kanagawa F-term (reference) 3G084 AA00 BA09 BA11 BA14 DA27 EA07 EA11 EB00 EB06 EB22 FA00 FA29 3G092 AB08 DE11Y DF08 EA09 EA14 EA17 EA28 EC09 FB02 FB03 FB06 HB 03Y HB04Y HD05X HD05Y HD05Z 3G301 HA22 JB01 JB02 JB09 JB10 NA08 NC01 ND01 PB01B PB08B PD02A PD02Z

Claims (6)

[Claims] 1. A failure for a gaseous fuel engine having a fuel cut-off valve, a fuel pressure regulator for adjusting fuel injection pressure, a first fuel pressure sensor for detecting fuel injection pressure, and a fuel injection valve in a fuel piping system. An engine control device including a diagnosis device, wherein the failure diagnosis device includes a first fuel pressure sensor diagnosis unit,
The first fuel pressure sensor diagnosis means compares first and second fuel pressure differences before and after operation based on the detection value of the first fuel pressure sensor, and the first fuel pressure sensor diagnosis means compares the detection value of the first fuel pressure sensor with the fuel pressure estimation value. A second comparing means for comparing the difference, and a third comparing means for comparing the fuel pressure correction value based on the detection value of the first fuel pressure sensor with a predetermined value and comparing the air-fuel ratio correction value with the predetermined value, An engine control device including a failure diagnosis device, wherein a function diagnosis of the first fuel pressure sensor is performed based on a comparison result of the comparison means. 2. The failure diagnosis device according to claim 1, further comprising a fuel cut-off valve diagnosis means, wherein the fuel cut-off valve diagnosis means detects a value detected by the first fuel pressure sensor when the fuel cut-off valve is opened and a value of the fuel cut-off valve. The engine control device according to claim 1, wherein a function diagnosis of the fuel cutoff valve is performed based on a difference from a value detected by the first fuel pressure sensor when the valve is closed. 3. The engine control system according to claim 2, wherein the failure diagnosis device performs a function diagnosis of the fuel cutoff valve after performing the function diagnosis of the first fuel pressure sensor. apparatus. 4. The engine control device according to claim 3, wherein the failure diagnosis device prohibits the subsequent diagnosis when an abnormality is detected in the diagnosis process. 5. The failure diagnosis device includes storage means for storing a failure history, which is a diagnosis result of each diagnosis, in a memory allocated to each diagnosis, and includes a failure warning device or an external diagnosis device. 5. The engine control device provided with the failure diagnosis device according to any one of claims 1 to 4, wherein the engine control device is connected to the external warning device and permits output to the external warning device when there is a failure history. 6. The engine control device according to claim 5, wherein the failure diagnosis device is capable of deleting the failure history in response to a deletion request from the external diagnosis device.