JP2005163755A - Fault detection device for injector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fault detection device for an injector capable of detecting a fault such as close adhesion in the injector. <P>SOLUTION: This fault detection device for the injector for detecting a fault caused in the injector 20 used in an internal combustion engine for gas fuel detects that the fault occurs in the injector based on a characteristic value related to opening and closing operation of the injector in a first condition in which the injector is driven by predetermined driving force and a characteristic value related to opening and closing operation of the injector in a second condition in which driving force of the injector is increased more than in the first condition. When the characteristic value related to the opening and closing operation of the injector is greatly changed (improved) due to increase in driving force of the injector when compared with a condition before driving force of the injector is increased, occurrence of the fault in the injector is detected. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an injector malfunction detection device, and more particularly to an apparatus for detecting malfunctions related to injection characteristics due to the fixation of an injector valve of an injector used in an internal combustion engine for gas fuel.

  In recent years, gases such as natural gas, hydrogen, and LPG have been used as automobile fuels in place of gasoline and light oil. Natural gas is stored in a fuel tank at high pressure because the energy density of the fuel is low, and a fuel injector is used to supply this compressed compressed natural gas (CNG) to the engine.

  In the injector device, an electric current is supplied to an electromagnetic coil of the injector by electronic control, and an injector valve is moved by a magnetic force to form a gap with an injection nozzle to inject fuel. As shown in FIG. 11, in the injector valve, when the electromagnetic coil a is energized through the terminal b, the movable iron core c is attracted upward, and when the valve d moves upward and separates from the valve seat e, the injection port f Be injected.

  In a gas fuel engine, particularly at the time of low temperature before completion of warm-up, the injection characteristics (fuel injection amount, etc.) of the injector change due to the influence of oil or the like in the fuel adhering to the injector. As a result, combustion fluctuations may occur, causing idle roughing (increasing fluctuations in engine speed) and the like.

  When the fuel is supplied through the compressor, such as CNG or hydrogen, the lubricating oil of the compressor is mixed. In the case of LPG, heavy components are present in the fuel. If these adhere to the seal part, the sliding part, etc. of the injector, the viscosity becomes high at low temperatures, so that the valve closing and opening delays of the injector valve change, and the injector injection characteristics change.

  Japanese Patent Laid-Open No. 2001-65395 (Patent Document 1) discloses the following technique as a technique related to a method for controlling an injector valve used in an internal combustion engine for gas fuel. A delivery gas pressure before or at the start of injector valve driving and a delivery gas pressure after starting the valve driving are detected, and a difference between the detected gas pressures is calculated. When the difference in gas pressure is smaller than a predetermined value, it is determined that the injector valve is fixed. Further, the rate of decrease in the delivery gas pressure after the start of the valve drive with respect to the delivery gas pressure at the timing of the valve drive start is calculated, and when this rate of decrease is smaller than a predetermined rate, it is determined that the injector valve is fixed. When it is determined that the injector valve is fixed, the time for energizing the injector is extended to drive the valve.

  Japanese Patent Application Laid-Open No. 2000-282905 (Patent Document 2) discloses the following technique as a technique for performing injection valve fixing peeling in a fuel injection valve control device used in an internal combustion engine for gaseous fuel. In a fuel injection valve control device that electromagnetically controls opening and closing of a fuel injection valve of a fuel injection device, the temperature of engine cooling water or the pressure of gas fuel or both are detected and detected at the start of the engine Based on the temperature and / or pressure, the number of times the fuel injection valve is driven by the boost driving is calculated, and the fuel injection valve is boosted by the calculated number of times. Furthermore, the time from when the fuel shut-off valve is closed to when the engine is stopped when the engine is stopped is calculated and stored, and the number of boost driving operations is adjusted based on this time when the engine is started.

JP 2001-65395 A JP 2000-282905 A

  As shown in Patent Document 1 and Patent Document 2 described above, the problem of sticking of an injector valve used in an internal combustion engine for gas fuel is that the time for energizing the electromagnetic coil of the injector is extended or the electromagnetic coil is larger than usual. This can be solved by increasing the driving force of the injector by flowing an electric current.

  However, if the driving force of the injector is increased, heat is generated from the electromagnetic coil of the injector, so that it cannot be performed constantly or every time (every time sticking occurs). The sticking of the injector is once eliminated by an increase in the driving force of the injector. However, instead of solving the problem by increasing the driving force of the injector every time the problem of the sticking of the injector occurs, the injector should be replaced or cleaned.

  On the other hand, for example, when an abnormal state such as a large fluctuation of the engine speed occurs, the cause is not always due to the fixation of the injector (for example, there may be a cause other than the injector such as an ignition system). . Therefore, when such an abnormal state occurs, even if the injector is cleaned or replaced, the problem may not be solved. It is desirable to be able to reliably detect that a malfunction such as sticking occurs in the injector.

  An object of the present invention is to provide an injector failure detection device capable of detecting that a failure such as sticking occurs in an injector.

  An injector failure detection device according to the present invention is an injector failure detection device that detects a failure that has occurred in an injector used in an internal combustion engine for gas fuel, in a first state in which the injector is driven with a predetermined driving force. Based on the characteristic value related to the opening / closing operation of the injector and the characteristic value related to the opening / closing operation of the injector in the second state in which the driving force of the injector is increased compared to the first state, a problem has occurred in the injector. It is characterized in that it is detected.

  If the characteristic value related to the opening / closing operation of the injector has changed (improved) significantly compared to before the injector driving force is increased due to the increase in the driving force of the injector, there is a problem with the injector. It is detected.

  In the injector malfunction detection device according to the present invention, the characteristic value related to the opening / closing operation of the injector is an injection characteristic value related to fuel injection by the injector.

  The injection characteristic value includes a characteristic value related to the fuel injection amount injected from the injector and a characteristic value related to combustion fluctuation.

  In the injector malfunction detection device according to the present invention, the injection characteristic value is at least one of fluctuations in engine speed, combustion pressure, and fuel pressure of an engine provided with the injector. .

In the injector malfunction detection device according to the present invention, the characteristic value relating to the opening / closing operation of the injector is a characteristic value relating to the opening / closing timing of the injector.

  In the injector malfunction detection device of the present invention, the operation for the detection is performed immediately after the engine provided with the injector is started. An injector malfunction occurs when the viscosity of the fuel oil or the like is high at a low temperature such as a warm-up state. Increasing the driving force of the injector in a situation where no malfunction of the injector occurs is not preferable in terms of heat generation of the coil of the injector.

  In the injector malfunction detection device of the present invention, the second state in which the driving force of the injector is increased as compared to the first state is generated when the water temperature of the engine provided with the injector is lower than a predetermined value. It is characterized by that.

  As described above, an injector malfunction occurs when the viscosity of fuel oil or the like is high at low temperatures. Therefore, increasing the driving force of the injector is not preferable in terms of heat generation of the coil of the injector in a situation where the injector does not malfunction even immediately after the engine is started.

  In the injector malfunction detection device of the present invention, the second state in which the driving force of the injector is increased as compared to the first state is generated based on a characteristic value relating to the opening / closing operation of the injector in the first state. It is characterized by that.

  If there is no problem with the characteristic value related to the opening / closing operation of the injector in the first state where the driving force of the injector is not increased, there is no problem with the injector. Increasing the driving force of the injector in a situation where there is no problem with the injector is not preferable in terms of heat generation of the coil of the injector.

  In the injector malfunction detection device of the present invention, the detection result relating to the occurrence of malfunction in the injector is notified to the user. Thereby, it is specified that the occurrence location of the failure (cause of the failure) is the injector, and the replacement and cleaning of the injector are promoted.

  In the injector malfunction detection device of the present invention, the detection result is notified to the user or stored in the ECU of the engine provided with the injector, depending on the detected malfunction level of the injector. It is characterized by being determined.

  If the degree of malfunction of the injector is not bad and it is not necessary to replace or clean the injector at that time, there is no need to notify the user. However, for subsequent failure diagnosis, a history of the malfunction of the injector should be retained.

  In the technique disclosed in Patent Document 1, when the amount of decrease in gas pressure is smaller than a predetermined amount, it is determined that the injector valve is fixed, and the valve is opened by extending the energization time for a certain time. ing. In the technique of Patent Document 1, control is performed such that the energization time is extended and the valve is opened each time the injector valve is fixed. In this sense, the electromagnetic coil of the injector often generates heat.

  On the other hand, as described above, the failure detection device for an injector of the present invention is not intended to eliminate the sticking of the injector, but can determine whether or not the cause of the failure is in the injector. It detects the presence or absence of defects. If the cause of the failure can be identified, it is possible to immediately replace or clean the injector.

    According to the injector malfunction detection device of the present invention, it is possible to detect that a malfunction such as sticking occurs in the injector.

  Hereinafter, an embodiment of an injector failure detection apparatus according to the present invention will be described in detail with reference to the drawings.

(First embodiment)
In the present embodiment, when the driving force of the injector is increased at a predetermined timing or periodically, and thereby fluctuations in engine speed (combustion fluctuations) are suppressed, the injectors due to oil in the fuel adhering to the injectors It is determined that the characteristic change is occurring, and the user is notified. As described above, it is possible to detect that the fixing failure occurs in the injector due to the change in the fluctuation of the engine speed before and after the driving force of the injector is increased. In this embodiment, the engine speed fluctuation is used as a parameter indicating the combustion fluctuation.

  FIG. 3 is a diagram showing an outline of a fuel supply system of a gas fuel internal combustion engine to which the fuel injection valve malfunction detection device of the present embodiment is applied.

In FIG. 3, reference numeral 10 denotes a fuel tank, which is filled with compressed fuel having a pressure of 200 to 250 kg / cm ² . A first gas cutoff valve 11 is provided at the outlet of the fuel tank 10, and a tank gas pressure sensor 12 and a tank gas temperature sensor 13 are provided beyond the first gas cutoff valve 11.

The fuel gas passes through the first gas shut-off valve 11 to the pressure regulator 14, and the gas pressure is lowered from, for example, 200 kg / cm ² to about 9 kg / cm ² to become a low pressure. A second gas shut-off valve 15 is provided at the inlet of the pressure regulator 14, and the gas fuel exits here and reaches the gas injector 20 through the delivery pipe 17.

  Then, under the control of the electronic control unit (ECU), an injector valve provided in the gas injector 20 is driven to inject gas. A third gas cutoff valve 16 is provided between the pressure regulator 14 and the gas injector 20. A delivery pipe 17 between the third gas cutoff valve 16 and the gas injector 20 is provided with a delivery gas pressure sensor 18 and a delivery gas. A gas temperature sensor 19 is provided.

  The engine 21 is a gas fuel engine. The engine 21 includes a valve 22, a spark plug 23, a piston 24, and a crankcase 25, and a combustion pressure sensor 26 is provided in the combustion chamber. Reference numeral 27 is a water temperature sensor, 28 is an engine speed sensor, and 29 is a vehicle speed sensor. On the intake side, an air cleaner 30, a throttle 31, an ISC valve 32, and a surge tank 33 are provided, and air is taken in through these. Reference numeral 34 denotes an intake air temperature sensor provided in the air cleaner 30, 35 denotes a throttle sensor linked to the throttle 31, and 36 denotes an intake air pressure sensor. A catalyst device 37 is provided on the exhaust side, and an A / F sensor (air-fuel ratio sensor) 38 is provided in front of it.

  FIG. 4 is a diagram showing an outline of the configuration of the injector malfunction detection device of the present embodiment.

  In FIG. 4, reference numeral 1 denotes an electronic control unit (ECU), which includes a CPU 2, an input interface 3, an A / D converter 4, and an output interface 5. Detection signals of various sensors shown in FIG. 3 are input to the input interface 3. Among these, the detection signals of the engine speed sensor 28 and the vehicle speed sensor 29 and the signal output from the starter switch signal generator 39 are digital signals, and are therefore input directly from the input interface 3 to the CPU 2.

  On the other hand, the detection signals of the delivery gas pressure sensor 18, delivery gas temperature sensor 19, tank gas pressure sensor 12, and tank gas temperature sensor 13, which are sensors relating to gas fuel, are analog signals, and thus are converted into digital signals by the A / D converter 4. And is input to the CPU 2. Since the throttle sensor 35, the water temperature sensor 27, the intake pressure sensor 36, and the A / F sensor 38 are also analog signals, they are converted into digital signals by the A / D converter 4 and input to the CPU 2.

  The CPU 2 performs gas injector injection control 5a such as opening / closing control by energizing the injector valve to the gas injector 20 via the output interface 5 based on the detection signals of the various sensors, and controls lighting and blinking of the warning light. 5b, ignition timing control 5c is performed on the spark plug 23, and control 5d is performed on the ISC valve 32.

  The ECU 1 includes a first counter CINJCK, a second counter CINJCK1, and a third counter CINJCK2. Each of the first counter CINJCK to the third counter CINJCK2 is, for example, a 64 ms counter. The first counter CINJCK is a counter that counts up regardless of the control content of the present embodiment described later. The second counter CINJCK1 counts the time during which the control of the injector characteristic check control step 1 is performed among the control contents of the present embodiment. The third counter CINJCK2 counts the time during which the control of the injector characteristic check control step 2 is performed among the control contents of the present embodiment.

  In the present embodiment, the following operation is performed.

  The operation of the present embodiment is performed by the ECU 1 when the engine 21 is idling. If the engine speed fluctuates while in the idling state, there is a possibility that combustion fluctuations have occurred due to changes in the injection characteristics of the gas injector 20. The ECU 1 detects that the engine 21 is idling based on a signal from the throttle sensor 35.

(1) The engine speed sensor 28 calculates the engine speed fluctuation (rotational fluctuation).
(2) The driving force of the gas injector 20 is increased at a predetermined timing or periodically. As the increase method, either a method of extending the energization time or a method of flowing a large current may be used.

  The time when the driving force of the gas injector 20 is increased is immediately after the engine 21 is started. This is because the gas injector 20 is fixed when the viscosity of the oil in the fuel is high at a low temperature such as when the engine 21 is not warmed up. The operation for increasing the driving force of the gas injector 20 can be performed every time immediately after the engine 21 is started.

  Further, the control for increasing the driving force of the gas injector 20 can be performed, for example, at intervals of several minutes when the engine 21 is in an idling state. However, when the warm-up operation of the engine 21 is finished and the temperature becomes sufficiently high, there is a high possibility that the problem of the gas injector 20 will not be fixed, so control for increasing the driving force of the gas injector 20 is performed. I will not. Note that the time required for detecting the characteristic change of the gas injector 20 according to the present embodiment is, for example, about 10 to 20 seconds.

(3) The fluctuation of the engine speed is calculated before and after the driving force of the gas injector 20 is increased in (2) above.

(4) The fluctuations in the engine speed before and after the driving force increase of the gas injector 20 calculated in (3) above are compared. As a result of the comparison, when the fluctuation of the engine speed when the driving force of the gas injector 20 is increased is smaller than a predetermined value than the fluctuation of the engine speed in the case of normal energization, that is, the combustion fluctuation When is reduced, it is determined that the characteristic change of the gas injector 20 has occurred.

  When the driving force of the gas injector 20 is increased and the fluctuation of the engine speed is greatly reduced (more than a predetermined value compared to the case of normal energization), the gas injector 20 that has been generated so far It can be determined that the problem of the sticking is solved by increasing the driving force of the gas injector 20.

(5) When it is determined in (4) that the characteristic change of the gas injector 20 is occurring, the user is notified.

  Next, an outline of the operation of the present embodiment will be described with reference to FIG.

In FIG. 2, the gas injector 20 in which the problem of sticking has occurred will be described.
At time t1 in FIG. 2, the engine 21 is started (see (a)), and at the same time, the gas injector 20 is driven with a normal driving force (see (b)). Since the gas injector 20 has a problem of sticking as described above, a large rotational fluctuation occurs simultaneously with the start of the engine 21 (see (d)).

  Next, at times t2 to t3, fluctuations in the rotational speed of the engine 21 before the driving force of the gas injector 20 is increased are calculated (see (c)). The calculation result is a relatively large value L1 (see (d)).

Next, at time t4, the driving force of the gas injector 20 is increased (see (b)). Thereby, rotational fluctuation is reduced (see (d)).
Next, at times t5 to t6, fluctuations in the rotational speed of the engine 21 after the driving force of the gas injector 20 is increased are calculated (see (c)). The calculation result is a relatively small value L2 (see (d)).

  As shown in FIG. 2, before and after the increase of the driving force of the gas injector 20, the rotational fluctuation is greatly reduced from L1 to L2. This indicates that the combustion fluctuation is improved by increasing the driving force of the gas injector 20, that is, there is a change in the characteristics of the gas injector 20.

  Next, the operation of this embodiment will be described with reference to FIG.

  The control flow of the present embodiment described below can be executed only when the engine 21 is started by the ECU 1. This is because the gas injector 20 is fixed when the engine 21 is at a low temperature, and the problem of the gas injector 20 is not fixed when the engine 21 is at a high temperature. For this reason, the control flow of the present embodiment can be performed only when the engine 21 is started and when the water temperature is lower than the threshold value.

  In the ECU 1, whether or not the engine 21 has been started is detected based on a signal output from the starter switch signal generator 39 in response to a driver's operation. In the ECU 1, the water temperature is detected based on the output value from the water temperature sensor 27.

[Step S10]
First, the ECU 1 determines whether or not it is time to start injector characteristic check control, that is, whether or not a predetermined time (A) determined in advance has elapsed since the last time this control was performed. The

  The first counter CINJCK measures the time that has elapsed since the last time this control was performed. The ECU 1 determines that it is time to perform this control when the counter value (CINJCK) by the first counter CINJCK exceeds a predetermined time (A) set in advance (step S10-Y), and step S20. Is done. On the other hand, when the counter value (CINJCK) by the first counter CINJCK does not exceed the predetermined time (A) set in advance (step S10-N), step S40 is performed.

[Step S20]
In step S20, the ECU 1 starts the injector characteristic check control step 1. When the injector characteristic check control step 1 is started, a variation rate of the engine speed (hereinafter referred to as a rotation variation rate) is integrated in another routine. That is, in the ECU 1, the engine speed of the engine 21 is input from the engine speed sensor 28, and the rotational fluctuation rate is integrated based on the engine speed. Here, the rotation fluctuation rate is the rotation fluctuation amount / rotation speed. In step S20, the ECU 1 sets an injector characteristic check control step 1 start flag (exinjck1). Next, step S30 is performed.

[Step S30]
In step S30, the ECU 1 clears the counter value CINJCK by the first counter CINJCK and the counter value CINJCK1 by the second counter CINJCK1. Following step S30, the control flow returns.

[Step S40]
In step S40, the ECU 1 determines whether or not the injector characteristic check control step 1 is already being performed. The determination is made based on whether or not the injector characteristic check control step 1 start flag (exinjck1) is set. As a result of the determination, when it is determined that the injector characteristic check control step 1 is being performed (step S40-Y), step S50 is performed. On the other hand, if it is determined as a result of the determination in step S40 that the injector characteristic check control step 1 is not being performed (step S40-N), step S90 is performed.

[Step S50]
In step S50, the ECU 1 determines whether or not a predetermined time (B) determined in advance has elapsed since the start of the injector characteristic check control step 1 based on the counter value CINJCK1 by the second counter CINJCK1. . The second counter CINJCK1 counts the time that has elapsed since it was cleared in step S30. As a result of the determination, when the predetermined time (B) has elapsed since the start of injector characteristic check control step 1 (step S50-Y), step S60 is performed. As a result of the determination, when the predetermined time (B) has not elapsed since the start of the injector characteristic check control step 1 (step S50-N), this control flow is returned.

[Step S60]
In step S60, the control of the injector characteristic check control step 1 by the ECU 1 ends. That is, the integration of the rotation fluctuation rate is finished. In step S60, the ECU 1 resets the injector characteristic check control step 1 start flag (exinjck1). Following step S60, step S70 is performed.

[Step S70]
In step S70, the ECU 1 calculates the average rotation fluctuation rate (dlne1) based on the rotation fluctuation rate integrated in the injector characteristic check control step 1. In step S70, the ECU 1 clears the counter value CINJCK1 by the second counter CINJCK and the counter value CINJCK2 by the third counter CINJCK2. Following step S70, step S80 is performed.

[Step S80]
In step S80, the ECU 1 starts the injector characteristic check control step 2. When the injector characteristic check control step 2 is started, the driving force of the gas injector 20 is increased in a separate routine, and integration of the rotational fluctuation rate in that state is started. That is, in the ECU 1, the engine speed of the engine 21 is input from the engine speed sensor 28, and the rotational fluctuation rate is integrated based on the engine speed. In step S80, the ECU 1 sets an injector characteristic check control step 2 start flag (exinjck2). Then, this control flow is returned.

[Step S90]
In step S90, the ECU 1 determines whether or not the injector characteristic check control step 2 is already being performed. This determination is made based on whether or not the injector characteristic check control step 2 start flag (exinjck2) is set. As a result of the determination, when it is determined that the injector characteristic check control step 2 is being performed (step S90-Y), step S100 is performed. On the other hand, as a result of the determination in step S90, when it is determined that the injector characteristic check control step 2 is not being executed (step S90-N), this routine is ended.

[Step S100]
In step S100, the ECU 1 determines based on the counter value CINJCK2 by the third counter CINJCK2 whether or not a predetermined time (C) determined in advance has elapsed since the start of the injector characteristic check control step 2. . The third counter CINJCK2 counts the time that has elapsed since being cleared in step S70. As a result of the determination, when the predetermined time (C) has elapsed since the start of the injector characteristic check control step 2 (step S100-Y), step S110 is performed. As a result of the determination, when the predetermined time (C) has not elapsed since the start of the injector characteristic check control step 2 (step S100-N), this control flow is returned.

[Step S110]
In step S110, the injector characteristic check control step 2 by the ECU 1 ends. That is, the driving force of the gas injector 20 is returned to the normal value, and the integration of the rotational fluctuation rate is completed. In step S110, the ECU 1 resets the injector characteristic check control step 2 start flag (exinjck2). Following step S110, step S120 is executed.

[Step S120]
In step S120, the ECU 1 calculates the average rotational fluctuation rate (dlne2) when the driving force of the gas injector 20 is increased based on the rotational fluctuation rate integrated in the injector characteristic check control step 2. In step S120, the ECU 1 clears the counter value CINJCK1 by the second counter CINJCK1 and the counter value CINJCK2 by the third counter CINJCK2. Following step S120, step S130 is performed.

[Step S130]
In step S130, the ECU 1 compares the average rotational fluctuation rate (dlne1) during normal energization with the average rotational fluctuation rate (dlne2) when the driving force of the gas injector 20 is increased. As a result of the comparison, when the average rotational fluctuation rate (dlne2) when the driving force of the gas injector 20 is increased is smaller than the average rotational fluctuation rate (dlne1) during normal energization exceeding a predetermined value (D) Step S140 is performed in (Step S130-Y). On the other hand, as a result of the comparison in step S130, the average rotational fluctuation rate (dlne2) when the driving force of the gas injector 20 is increased to a predetermined value (D) rather than the average rotational fluctuation rate (dlne1) during normal energization. If it is not too small (step S130-N), this control flow is returned.

[Step S140]
In step S140, the ECU 1 determines that the combustion fluctuation has been improved by increasing the driving force of the gas injector 20, that is, that there is a change in the characteristics of the gas injector 20, and the user is informed that the characteristic change has occurred in the gas injector 20. Will be announced. The notification to the user can be made by turning on the warning lamp 5b.

  In step S140, as described above, the following change can be made without notifying the user by always lighting the warning lamp 5b. Here, for example, the notification method to the user can be changed depending on the magnitude of the improvement rate of the rotational fluctuation rate (corresponding to the value of dlne1-dlne2) in step S130.

  That is, when the value of (dlne1-dlne2) obtained in step S130 is larger than the threshold value, the gas injector 20 is relatively close to a failure state, and the driving force of the gas injector 20 is returned to a normal value. Then, there is a high possibility of returning to the fixed state again. Therefore, when the value of (dlne1-dlne2) is larger than the threshold value, the warning lamp 5b is turned on to notify the user that a characteristic change has occurred in the gas injector 20.

  On the other hand, when the value of (dlne1-dlne2) is not larger than the threshold value, the ECU 1 stores data indicating that a characteristic change has occurred in the gas injector 20 instead of notifying the user at that time. Let me leave it to you. In this case, the service person can perform a failure diagnosis of the gas injector 20 by analyzing the ECU 1 according to a predetermined procedure.

  In this case, if conditions such as the engine water temperature that cause fluctuations in the engine speed change before and after the driving force of the gas injector 20 is changed, the conditions are affected (originally the engine It is conceivable that the engine speed changes before and after the driving force of the gas injector 20 increases, despite the fact that there is no change in the engine speed.

  However, since the time required for performing the control flow of the present embodiment (the time required for detecting the presence or absence of the characteristic change of the gas injector 20) is as short as 10 to 20 seconds, for example, conditions such as water temperature The change in the engine speed fluctuation caused by the change in the value is not substantially a problem.

  On the other hand, if the required time for detecting the presence or absence of the characteristic change of the gas injector 20 is long and the change in the engine speed due to the change in conditions such as the water temperature becomes a problem, for example, The value of the average rotational fluctuation rate dlne1 obtained in step S70 or the average rotational fluctuation rate dlne2 obtained in step S120 so as to substantially cancel the change in the engine rotational speed caused by changes in conditions such as water temperature. Can be corrected by multiplying by a predetermined coefficient.

  In the above control flow, the presence or absence of the characteristic change of the gas injector 20 is determined based on the rotation fluctuation rate. However, the characteristic change of the gas injector 20 is changed based on the rotation fluctuation amount instead of the rotation fluctuation rate. It is also possible to determine the presence or absence.

  According to the first embodiment, when the driving force of the gas injector 20 is increased and thereby the combustion fluctuation indicated by the rotation fluctuation rate is suppressed, it is determined that the characteristic change of the gas injector 20 has occurred. The determination result is notified to the user. Thereby, when idle roughing arises, it can be specified whether the cause is the characteristic change (adhesion) of the gas injector 20.

Next, a modification of the first embodiment will be described with reference to FIG.
In this modification, the description of the points in common with the first embodiment will be omitted.

  As described above, the operation for increasing the driving force of the injector is accompanied by heat generation of the coil of the injector. Therefore, it is preferable that the operation for increasing the driving force of the injector is not performed if not necessary. From this, in this modification, as shown in FIG. 5, step S75 is added compared with FIG.

[Step S75]
In step S75, the average rotation fluctuation rate (dlne1) obtained as a result of the injector characteristic check control step 1 at the normal time (when the driving force of the gas injector 20 is not increased) is set to a predetermined threshold value (dlne1). It is determined whether or not E) is exceeded. As a result of the determination in step S75, when the average average rotation fluctuation rate (dlne1) does not exceed the threshold value (E) (S75-N), this control flow is returned. As a result of the determination in step S75, the injector characteristic check control step 2 (injector driving force is increased only when the average rotation fluctuation rate (dlne1) in the normal state exceeds the threshold value (E) (S75-Y). Control).

  When the average rotation fluctuation rate (dlne1) at normal time is equal to or less than the threshold value (E), idle rough (a state in which the fluctuation of idling rotation speed as the average rotation fluctuation rate (dlne1) at normal time is large) occurs. Therefore, it is determined that the problem of sticking of the gas injector 20 (change in characteristics) has not occurred. When it is determined that the gas injector 20 is not fixed, the operation for increasing the driving force of the gas injector 20 is not performed. Thereby, the heat_generation | fever of the coil of the gas injector 20 is suppressed.

  Next, a second embodiment will be described with reference to FIG. In the second embodiment, the description of the parts common to the above embodiment and the modified example is omitted.

  FIG. 6 is a flowchart showing the operation of the second embodiment. 6, step S10A corresponds to step S10 in FIG. 1, step S20A corresponds to step S20 in FIG. 1, step S30A corresponds to step S30 in FIG. 1,. Corresponds to step S140 in FIG. In the following, the operation of the second embodiment will be described with respect to differences from the operation of the first embodiment, and description of similar steps will be omitted.

  In the first embodiment, the fluctuation of the engine speed is used as a parameter indicating the combustion fluctuation, whereas in the second embodiment, the fluctuation of the combustion pressure is used as a parameter indicating the combustion fluctuation.

[Step S20A]
In step S20A, the ECU 1 starts the injector characteristic check control step 1A. When the injector characteristic check control step 1A is started, the variation rate of the combustion pressure (hereinafter referred to as the combustion pressure variation rate) is integrated in another routine.

  That is, in the ECU 1, the combustion pressure of the engine 21 is input from the combustion pressure sensor 26, and the combustion pressure fluctuation rate is integrated based on the combustion pressure. Here, the combustion pressure fluctuation rate is the combustion pressure fluctuation amount / combustion pressure. In step S20A, the ECU 1 sets an injector characteristic check control step 1A start flag (exinjck1A).

[Step S60A]
In step S60A, the control of the injector characteristic check control step 1A by the ECU 1 ends. That is, the integration of the combustion pressure fluctuation rate is completed. In step S60A, the ECU 1 resets the injector characteristic check control step 1A start flag (exinjck1A). Following step S60A, step S70A is performed.

[Step S70A]
In step S70A, the ECU 1 calculates the average combustion pressure fluctuation rate (dlpc1) based on the combustion pressure fluctuation rate integrated in the injector characteristic check control step 1A. Following step S70A, step S80A is performed.

[Step S80A]
In step S80A, the ECU 1 starts the injector characteristic check control step 2A. When the injector characteristic check control step 2A is started, the driving force of the gas injector 20 is increased in another routine, and the integration of the combustion pressure fluctuation rate in that state is started. That is, in the ECU 1, the combustion pressure is input from the combustion pressure sensor 26, and the combustion pressure fluctuation rate is integrated based on the combustion pressure.

[Step S110A]
In step S110A, the injector characteristic check control step 2A by the ECU 1 ends. That is, the driving force of the gas injector 20 is returned to the normal value, and the integration of the combustion pressure fluctuation rate is completed.

[Step S120A]
In step S120A, the ECU 1 calculates the average combustion pressure fluctuation rate (dlpc2) when the driving force of the gas injector 20A is increased based on the combustion pressure fluctuation rate integrated in the injector characteristic check control step 2A.

[Step S130A]
In step S130A, the ECU 1 compares the average combustion pressure fluctuation rate (dlpc1) during normal energization with the average combustion pressure fluctuation rate (dlpc2) when the driving force of the gas injector 20 is increased. As a result of the comparison, the average combustion pressure fluctuation rate (dlpc2) when the driving force of the gas injector 20 is increased exceeds the predetermined value (F) than the average combustion pressure fluctuation rate (dlpc1) during normal energization. If it is smaller (steps S130A-Y), step S140A is performed.

  On the other hand, as a result of the comparison in step S130A, the average combustion pressure fluctuation rate (dlpc2) when the driving force of the gas injector 20 is increased is higher than the average combustion pressure fluctuation rate (dlpc1) during normal energization by a predetermined value (F ), The control flow is returned (step S130A-N).

[Step S140A]
In step S140A, the ECU 1 determines that the combustion fluctuation has been improved by increasing the driving force of the gas injector 20, that is, that the characteristic change of the gas injector 20 has occurred, and that the characteristic change has occurred in the gas injector 20. Will be announced. The notification to the user can be made by turning on the warning lamp 5b.

  According to the second embodiment, when the combustion fluctuation indicated by the fluctuation in the combustion pressure is suppressed by increasing the driving force of the gas injector 20, it is determined that the characteristic change of the gas injector 20 has occurred. The

  Next, a third embodiment will be described with reference to FIG. 7, FIG. 8, and FIG. In the third embodiment, the description of the parts common to the above-described embodiments and modifications is omitted.

  FIG. 7 is a flowchart showing the operation of the third embodiment. 7, step S10B corresponds to step S10 in FIG. 1, step S20B corresponds to step S20 in FIG. 1, step S30B corresponds to step S30 in FIG. 1,. Corresponds to step S140 in FIG. In the following, the operation of the third embodiment will be described with respect to differences from the operation of the first embodiment, and description of similar steps will be omitted.

  In the first embodiment, the engine speed fluctuation is used as a parameter indicating combustion fluctuation, whereas in the third embodiment, fuel pressure fluctuation is used as a parameter indicating combustion fluctuation.

  According to the third embodiment, when the driving force of the gas injector 20 is increased and thereby the combustion fluctuation indicated by the gas pressure (fuel pressure) of the delivery pipe 17 is suppressed, the characteristic change of the gas injector 20 is changed. Is determined to occur, and the determination result is notified to the user.

In FIG. 3, the pressure of the gas exiting the pressure regulator 14 is about 9 kg / cm ² as described above. Therefore, when the injector valve of the gas injector 20 is closed, the pressure detected by the delivery gas pressure sensor 18 provided in the delivery pipe 17 is normally about 9 kg / cm ² . However, if the valve of the injector 20 is opened at the time of gas injection, the detected pressure is temporarily reduced.

  FIG. 8 is a diagram for explaining the injector characteristic check control step 1B performed in step S20B. In the injector characteristic check control step 1B, the electromagnetic coil of the gas injector 20 is energized during a normal energization time.

The symbol (a) in FIG. 8 represents the timing of energizing the electromagnetic coil to open the injector valve of the injector 20 during gas injection. As shown to (a), electricity supply is started at the time t0, and electricity supply is stopped at the time t1. The energization time T0 is determined in advance and is, for example, 15 milliseconds.
A symbol (b) in FIG. 8 represents a change in the detected pressure (DGP) of the delivery gas pressure sensor 18. The detected pressure (P1) when the injector valve is closed is substantially the same as the pressure of the gas exiting the pressure regulator 14.

  When the injector valve is not fixed and the valve is normally opened, the gas is injected from the gas injector 20, so that the DGP temporarily decreases to P2. As shown in FIG. 8B, the gas pressure reaches a peak of decrease and increases again in the middle of the energization period T0 to the electromagnetic coil of the injector 20, but when the gas pressure decreases due to injection, the pressure is increased. This is because the regulator 14 adjusts to increase the gas pressure. When energization is completed at time t1, the valve is closed, so that DGP immediately becomes P1. In addition, since it does not open when the valve | bulb has adhered, DGP shown to (b) does not fall as shown by a dotted line.

  FIG. 9 is a diagram for explaining the injector characteristic check control step 2B performed in step S80B. In the injector characteristic check control step 2B, the electromagnetic coil of the gas injector 20 is energized for a longer energization time than usual. The symbol (a) in FIG. 9 represents the timing when the electromagnetic coil is energized to open the injector valve, similarly to the symbol (a) in FIG.

  In the injector characteristic check control step 2B, the energization time is longer by α than the injector characteristic check control step 1B, and is set to (T0 + α) time, and energization is performed until time t2. For example, when T0 = 15 milliseconds, α = 7.5 milliseconds, but the extension time α can be changed according to the situation.

  Symbols (b) and (c) in FIG. 9 represent changes in DGP at that time, as in symbol (b) in FIG. FIG. 9B shows a change in DGP when the injector valve is fixed, and FIG. 9C shows the DGP when the injector valve is not fixed and the valve opens normally. It shows a change.

  Energization is started at time t0 as shown in FIG. 9A, but when the injector valve is fixed as shown in FIG. 9B, normal driving force (injector characteristic check control step 1B). In the energizing time), that is, at a time point before the time t1. As shown in FIG. 9B, at time t1 corresponding to the normal driving force, DGP does not decrease and remains P1. In a time zone after t1 corresponding to an increase in driving force (extension of energization time), the injector valve is opened and DGP is lowered.

  On the other hand, when the injector valve is not fixed, as shown in FIG. 9C, the time zone of the normal driving force (energization time of the injector characteristic check control step 1B), that is, before the time t1. At this time, the opening operation is normally performed, and the gas is injected from the gas injector 20, so that DGP temporarily decreases to P2. In the middle of the energization period (normal drive force energization time) T0 of the injector 20, the gas pressure reaches a peak of decrease and rises again. However, when the gas pressure is lowered by injection, the pressure regulator 14 This is to adjust and increase the gas pressure. When energization is completed at time t2, the valve is closed, so that DGP immediately becomes P1.

  Next, the operation of the third embodiment will be described with reference to FIG. In the following, differences in the operation of the third embodiment from the operation of the first embodiment will be described.

[Step S20B]
In step S20B, the ECU 1 starts the injector characteristic check control step 1B. When this injector characteristic check control step 1B is started, the delivery gas pressure (DGP) is integrated in a separate routine. That is, the ECU 1 receives the detection pressure (DGP) of the delivery gas pressure sensor 18 at time t1 in FIG. 8 and integrates the detection pressure (DGP). In this case, the detected pressure (DGP) at time t1 of the gas injector 20 with sticking is P1, and the detected pressure (DGP) at time t1 of the gas injector 20 without sticking is also P1. In step S20B, the ECU 1 sets an injector characteristic check control step 1B start flag (exinjck1B).

[Step S60B]
In step S60B, the control of the injector characteristic check control step 1B by the ECU 1 ends. That is, the integration of the delivery gas pressure (DGP) is terminated. In step S60B, the ECU 1 resets the injector characteristic check control step 1B start flag (exinjck1B). Following step S60B, step S70B is performed.

[Step S70B]
In step S70B, the ECU 1 calculates an average delivery gas pressure (dldgp1) based on the delivery gas pressure (DGP) integrated in the injector characteristic check control step 1B. Following step S70B, step S80B is performed.

[Step S80B]
In step S80B, the ECU 1 starts the injector characteristic check control step 2B. When this injector characteristic check control step 2B is started, in another routine, the driving force of the gas injector 20 is increased by extending the energization time for the electromagnetic coil, and the delivery gas pressure (DGP) in that state is started to be accumulated. Is done. That is, the ECU 1 receives the detection pressure (DGP) of the delivery gas pressure sensor 18 at time t2 in FIG. 9, and integrates the detection pressure (DGP). In this case, the detected pressure (DGP) at the time t2 of the gas injector 20 with the sticking becomes P2, and the detected pressure (DGP) at the time t2 of the gas injector 20 without the sticking becomes P1. In step S80B, the ECU 1 sets an injector characteristic check control step 2B start flag (exinjck2B).

[Step S110B]
In step S110B, the injector characteristic check control step 2B by the ECU 1 ends. That is, the driving force of the gas injector 20 (the energization time to the electromagnetic coil) is returned to the normal value, and the delivery gas pressure (DGP) integration is completed.

[Step S120B]
In step S120B, the ECU 1 calculates the average delivery gas pressure (dldgp2) based on the delivery gas pressure (DGP) integrated in the injector characteristic check control step 2B.

[Step S130B]
In step S130B, the ECU 1 compares the average delivery gas pressure (dldgp1) during normal energization with the average delivery gas pressure (dldgp2) when the driving force of the gas injector 20 is increased.

  The lddgp1 of the gas injector 20 with sticking is in the vicinity of P1, and the lddgp1 of the gas injector 20 without sticking is in the vicinity of P1. The lddgp2 of the gas injector 20 with sticking is in the vicinity of P2, and the lddgp2 of the gas injector 20 without sticking is in the vicinity of P1. Therefore, lddgp1-dldgp2> 0 of the gas injector 20 with sticking is satisfied, and ldgp1-dlldgp2 of the gas injector 20 without sticking is approximately zero.

  As a result of the comparison in step S130B, the average delivery gas pressure (dldgp2) when the driving force of the gas injector 20 is increased exceeds the predetermined value (G) than the average delivery gas pressure (dldgp1) during normal energization. If it is smaller (step S130B-Y), step S140B is performed.

  On the other hand, as a result of the comparison in step S130B, the average delivery gas pressure (dldgp2) when the driving force of the gas injector 20 is increased to a predetermined value (G) rather than the average delivery gas pressure (dldgp1) during normal energization. If it is not too small (step S130B-N), this control flow is returned.

[Step S140B]
In step S140B, the ECU 1 determines that the combustion fluctuation has been improved by increasing the driving force of the gas injector 20, that is, the characteristic change of the gas injector 20 has occurred. Will be announced. The notification to the user can be made by turning on the warning lamp 5b.

  In the other routine of the injector characteristic check control step 1B in step S20B described above, the ECU 1 receives the detected pressure (DGP) of the delivery gas pressure sensor 18 at time t1 in FIG. 8, and the detected pressure (DGP) is It explained that it would be accumulated. Instead, in the other routine of the injector characteristic check control step 1B in step S20B described above, at an intermediate time point between times t0 and t1 in FIG. 8 (when the delivery gas pressure of the gas injector 20 without sticking becomes P2). A configuration in which the detection pressure (DGP) of the delivery gas pressure sensor 18 is input and the detection pressure (DGP) is integrated can be employed. In that case, the detected pressure (DGP) of the gas injector 20 with sticking is P1, and the detected pressure (DGP) of the gas injector 20 without sticking is similarly P2. In step S130B, the ldgp1 of the gas injector 20 with sticking is in the vicinity of P1, and the ldgp1 of the gas injector 20 without sticking is in the vicinity of P2. The lddgp2 of the gas injector 20 with sticking is in the vicinity of P2, and the lddgp2 of the gas injector 20 without sticking is in the vicinity of P1. Therefore, it follows that lddgp1-dldgp2> 0 of the gas injector 20 with sticking, and ldgp1-dlldgp2 <0 of the gas injector 20 without sticking.

  According to the third embodiment, when the combustion fluctuation indicated by the delivery gas pressure is suppressed by increasing the driving force of the gas injector 20, it is determined that the characteristic change of the gas injector 20 has occurred. .

Next, a fourth embodiment will be described with reference to FIG.
In the fourth embodiment, description of parts common to the above embodiment is omitted.

  In the first to third embodiments, whether or not a characteristic change has occurred in the gas injector 20 is detected depending on whether or not combustion fluctuation is suppressed before and after increasing the driving force of the gas injector 20. On the other hand, in the fourth embodiment, it is possible to detect whether a characteristic change has occurred in the gas injector 20 due to a delay in opening and closing timing of the gas injector 20.

  As shown in FIG. 10, when the problem of sticking due to oil has occurred in the gas injector 20, the delay amount of the opening / closing timing of the gas injector 20 (injector valve) compared to the case where there is no sticking problem. Becomes larger. A symbol (a) in FIG. 10 indicates an open / close command signal from the ECU 1 to the gas injector 20. The opening / closing command signal is a rectangular wave signal. At the rising time t1, the opening of the gas injector 20 is instructed, and at the falling time t2, the closing of the gas injector 20 is instructed.

  The solid line of the code | symbol (b) of FIG. 10 has shown the opening degree when the problem of the adhesion | attachment by the oil to the gas injector 20 has not arisen. Even when there is no sticking, the gas injector 20 is opened and closed with a response delay with respect to the opening time t1 and the closing time t2 of the opening / closing command signal in FIG. Become.

  The two-dot chain line of the symbol (b) in FIG. 10 indicates the opening when the gas injector 20 has a problem of sticking with oil. When there is sticking, the gas injector 20 has a larger response delay with respect to the opening time t1 and the closing time t2 of the opening / closing command signal in FIG. 10A than when there is no sticking. Are opened and closed. In other words, when the gas injector 20 has a problem of sticking, the opening / closing timing is delayed as compared with the case where there is no sticking.

  The response delay amounts of opening and closing of the gas injector 20 when the gas injector 20 is stuck vary depending on the position where the oil is attached. Further, the respective response delay amounts of opening and closing of the gas injector 20 when the gas injector 20 is fixed are performed each time an opening / closing command signal is output from the ECU 1.

  In the fourth embodiment, before and after the driving force of the gas injector 20 is increased, the delay amount of the opening / closing timing of the gas injector 20 in (b) with respect to the opening / closing instruction command from the ECU 1 in FIG. When the difference is large, it is determined that the characteristic change has occurred in the gas injector 20, and the user is notified.

  That is, after increasing the driving force of the gas injector 20 as compared with the delay amount of the opening / closing timing of the gas injector 20 in (b) with respect to the opening / closing instruction command from the ECU 1 before increasing the driving force of the gas injector 20. When the amount of delay is significantly reduced, it is determined that the problem of sticking of the gas injector 20 has been solved by increasing the driving force of the injector (there is a change in the characteristics of the gas injector 20).

  According to the fourth embodiment, when the driving force of the gas injector 20 is increased, the combustion fluctuation indicated by the opening / closing timing delay amount of the gas injector 20 with respect to the opening / closing command or the opening / closing timing itself is suppressed. It is determined that the characteristic change of the gas injector 20 has occurred.

  In addition, said embodiment can be combined suitably. For example, it is possible to determine whether or not the characteristic change of the gas injector 20 has occurred based on both the engine rotation fluctuation rate and the combustion pressure, or based on both the engine rotation fluctuation rate and the injector opening / closing timing. .

It is a flowchart which shows the control method of 1st Embodiment of the malfunction detection apparatus of the injector of this invention. It is a time chart which shows operation | movement of 1st Embodiment of the malfunction detection apparatus of the injector of this invention. It is explanatory drawing which shows the outline | summary to the fuel supply system of the internal combustion engine for gas fuel to which 1st Embodiment of the malfunction detection apparatus of the injector of this invention was applied. It is a block diagram for demonstrating the structure of 1st Embodiment of the malfunction detection apparatus of the injector of this invention. It is a flowchart which shows the control method of the modification of 1st Embodiment of the malfunction detection apparatus of the injector of this invention. It is a flowchart which shows the control method of 2nd Embodiment of the malfunction detection apparatus of the injector of this invention. It is a flowchart which shows the control method of 3rd Embodiment of the malfunction detection apparatus of the injector of this invention. In 3rd Embodiment of the malfunction detection apparatus of the injector of this invention, it is a figure which shows the relationship between the energization time of an injector, and delivery gas pressure. In 3rd Embodiment of the malfunction detection apparatus of the injector of this invention, it is a figure which shows the other relationship between the electricity supply time of an injector, and delivery gas pressure. In 4th Embodiment of the malfunction detection apparatus of the injector of this invention, it is a figure which shows the relationship between the opening / closing command of an injector, and the opening degree of an injector. It is explanatory drawing for demonstrating the conventional general injector.

Explanation of symbols

1 ECU
5a Warning light 17 Delivery pipe 18 Delivery gas pressure sensor 20 Gas injector 21 Engine 26 Combustion pressure sensor 28 Engine speed sensor 35 Throttle sensor 39 Starter switch signal generator

Claims (9)

An injector malfunction detection device for detecting malfunctions occurring in an injector used in an internal combustion engine for gas fuel,
Characteristic values relating to the opening / closing operation of the injector in the first state in which the injector is driven with a predetermined driving force, and the opening / closing operation of the injector in the second state in which the driving force of the injector is increased as compared with the first state. An injector failure detection device that detects that a failure has occurred in the injector based on a characteristic value related to the injector. The injector malfunction detection device according to claim 1,
The injector failure detection device, wherein the characteristic value related to the opening / closing operation of the injector is an injection characteristic value related to fuel injection by the injector. In the injector malfunction detection device according to claim 2,
The injector failure detection device, wherein the injection characteristic value is at least one of fluctuations in engine speed, combustion pressure, and fuel pressure of an engine provided with the injector. The injector malfunction detection device according to claim 1,
The injector failure detection device, wherein the characteristic value related to the opening / closing operation of the injector is a characteristic value related to the opening / closing timing of the injector. In the injector malfunction detection device according to any one of claims 1 to 4,
The operation for the detection is performed immediately after the start of the engine provided with the injector. In the malfunction detection apparatus of the injector of any one of Claim 1 to 5,
The second state in which the driving force of the injector is increased as compared to the first state is generated when the water temperature of the engine provided with the injector is lower than a predetermined value. apparatus. In the injector malfunction detection device according to any one of claims 1 to 6,
Injector failure detection, wherein the second state in which the driving force of the injector is increased as compared to the first state is generated based on a characteristic value relating to the opening / closing operation of the injector in the first state. apparatus. In the injector malfunction detection device according to any one of claims 1 to 7,
The failure detection apparatus for an injector, wherein the detection result regarding the occurrence of the failure in the injector is notified to a user. The injector malfunction detection device according to claim 8,
Whether the detected result is notified to the user or stored in the ECU of the engine provided with the injector is determined according to the detected malfunction of the injector. Injector malfunction detection device.

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