JP2013104343A - Fuel shutoff valve diagnosis apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel shutoff valve diagnosis apparatus properly diagnosing a valve state of a shutoff valve used for shutting off fuel gas, in an engine using the fuel gas as fuel.SOLUTION: The fuel shutoff valve diagnosis apparatus diagnoses a valve function of a shutoff valve, based on fuel pressure detected by a pressure sensor provided between the fuel tank and the engine. The shutoff valve is opened/closed to allow/prohibit supply of the fuel gas from a fuel tank to the engine. The fuel shutoff valve diagnosis apparatus closes the shutoff valve during operation of the engine, monitors a consumption amount F1 of the fuel gas, which is an amount of the fuel gas supplied to the engine by injection, from a time when the shutoff valve is closed, and diagnoses the valve function of the shutoff valve, on a condition that an accumulated value of the accumulated fuel consumption amount F1 of the fuel gas reaches a consumption amount threshold FT as a predetermined value.

Description

  The present invention relates to a fuel cutoff valve diagnosis device that diagnoses the state of a fuel cutoff valve that shuts off the supply of fuel to an engine that uses gas fuel or the like as fuel.

  Conventionally, in a vehicular engine using CNG (compressed natural gas) as a gas fuel, the gas fuel in the fuel tank is supplied with an appropriate pressure to a delivery pipe to which an injector as a fuel injection valve is connected. A fuel supply device is provided. In general, this fuel supply device includes a pressure regulator that adjusts the supply pressure of gas fuel to the delivery pipe, a fuel shut-off valve (shutoff valve) that stops fuel supply from the fuel tank, and the like between the fuel tank and the delivery pipe. It is provided in the piping that connects them. Here, the shut-off valve is a valve that is closed when the engine is stopped or when the fuel supply system is abnormal, etc., forcibly stopping the fuel supply. There may be inconveniences in the forced stop of fuel. However, even if such a valve closing failure occurs in the shut-off valve, it is difficult to determine such a valve closing failure if the fuel pressure is properly adjusted by the pressure regulator. It often happens. For this reason, for example, a device described in Patent Document 1 has been proposed as a device for diagnosing the valve state of the shut-off valve.

  The device described in Patent Document 1 is in the fuel supply device as described above, and in order to diagnose the valve state of the shut-off valve, the shut-off valve is closed during operation of the engine, and after closing the shut-off valve, The amount of decrease in fuel pressure in the piping within the diagnosis time is detected. If the detected amount of decrease in fuel pressure exceeds a predetermined reference value, it is determined that the shut-off valve is normally closed. On the other hand, if the amount of decrease in fuel pressure is less than the predetermined reference value, Judge that the valve is not closed properly. Thus, the quality of the shut-off valve is diagnosed.

Japanese Patent No. 3859925

  According to the device described in Patent Document 1, it is possible to diagnose the valve closing failure of the shut-off valve. However, since the fuel consumption of the engine fluctuates depending on the load condition and the like, there are some points to be noted when diagnosing with the same device that closes the shut-off valve for a predetermined diagnosis time. For example, when the fuel consumption of the engine is large, as shown in FIG. 7A, when the shut-off valve is closed at the time Ts when the diagnosis is started, the fuel pressure is greatly reduced, and the diagnosis ends. At time Te, the fuel pressure greatly falls below a diagnostic threshold (reference value) PT for determining whether there is a valve closing failure. Thereby, it is determined that the shut-off valve is in a good state with no valve sticking. In this case, however, the fuel pressure may drop to a lower limit pressure PB that is insufficient for fuel injection. On the other hand, when the fuel consumption of the engine is small, as shown in FIG. 7B, the fuel pressure that decreases between the start time Ts and the end time Te is very small. The amount that the fuel pressure falls below the diagnostic threshold PT is naturally reduced. Therefore, if low fuel consumption control such as fuel cut is performed during the diagnosis and the fuel consumption may further decrease, the fuel pressure will not decrease to the diagnosis threshold PT by the end time Te and the fuel consumption will be closed. There is also a possibility that it is erroneously determined that the valve is defective.

  The present invention has been made in view of such circumstances, and an object thereof is an engine using gas fuel as a fuel, and more appropriately diagnoses the valve state of a shut-off valve used for shutting off the gas fuel. It is an object of the present invention to provide a fuel cutoff valve diagnostic device capable of performing the above.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
In order to solve the above-mentioned problem, the invention according to claim 1 is characterized in that a valve function of a shut-off valve that permits or prohibits the supply of gas fuel from the fuel tank to the engine by opening and closing the valve between the fuel tank and the engine. A fuel shut-off valve diagnosis device for diagnosing based on a fuel pressure detected by a pressure sensor provided therebetween, when the shut-off valve is closed during operation of the engine and the shut-off valve is closed The gist of the present invention is to monitor the consumption of gas fuel injected from the engine to the engine and diagnose the valve function of the shut-off valve on condition that the accumulated value of the consumption of gas fuel reaches a predetermined value.

  According to such a configuration, after the shut-off valve is closed, the cumulative value of the consumption amount of gas fuel remaining between the shut-off valve supplied to the engine and the engine reaches the predetermined value to shut off. The valve function of the valve is determined. As a result, the predetermined value of the fuel consumption required for determining the valve function of the shut-off valve can be quantified, so that a diagnosis that is not influenced by the amount of fuel consumption of the engine can be performed. At this time, if the predetermined value of the fuel consumption is set to an appropriate value corresponding to the amount of gas fuel remaining between the shut-off valve and the engine, if the fuel consumption by the engine is large, the engine This prevents the fuel supply from being insufficient, and conversely, when the fuel consumption is small, the decrease in the fuel pressure is reduced and the valve function cannot be properly diagnosed. Further, the diagnosis of the valve function of the shut-off valve is performed in a short time when the fuel consumption by the engine is large. On the other hand, when the fuel consumption is small, the necessary time is secured. That is, the time required for diagnosing the valve function of the shutoff valve is appropriately adjusted according to the fuel consumption of the engine.

Thus, according to this fuel cutoff valve diagnostic device, the valve function of the cutoff valve can be appropriately diagnosed regardless of the amount of fuel consumption of the engine.
According to a second aspect of the present invention, in the fuel shut-off valve diagnostic device according to the first aspect, the diagnosis of the valve function of the shut-off valve is performed when the accumulated value of the consumption amount of the gas fuel reaches the predetermined value. The gist is that the comparison is made between the detected fuel pressure and a pressure determination value capable of determining the presence or absence of a valve closing failure.

  According to such a configuration, if the diagnosis of the quality of the valve function of the shut-off valve is performed, the fuel pressure when the valve is open decreases due to the valve closing, and the fuel that passes during the diagnosis if the valve function is normal The pressure threshold value is set as a pressure judgment value. If such a pressure determination value is set, it becomes possible to diagnose the presence or absence of valve closing failure such as valve sticking depending on whether or not the fuel pressure drops to the pressure determination value.

  According to a third aspect of the present invention, in the fuel cutoff valve diagnostic device according to the second aspect, when the detected fuel pressure is higher than the pressure judgment value, the valve function of the cutoff valve is poorly closed. The gist is to diagnose it.

  According to such a configuration, when the fuel pressure is high with respect to the pressure determination value, the shut-off valve has a malfunction in the valve closing function (such as valve malfunction) such as the valve opening sticking that remains open. Diagnosed. In other words, since the fuel pressure is higher than the pressure judgment value, it is determined that gas fuel is being supplied from the fuel tank through the shut-off valve even though the shut-off valve is closed, and the shut-off valve is completely closed. It is detected that the valve is not valved, that is, a valve closing failure such as open sticking occurs.

  According to a fourth aspect of the present invention, in the fuel shut-off valve diagnostic device according to the second or third aspect, the diagnosis of the valve function of the shut-off valve is started on the condition that the fuel pressure is higher than the pressure judgment value. The gist is that

  According to such a configuration, since the fuel pressure is higher than the pressure determination value when the shutoff valve is closed, the fuel pressure approaches the pressure determination value due to a decrease in the fuel pressure due to the valve closing. Thereby, the quality of the closing function of the shut-off valve can be diagnosed by comparison with the pressure determination value.

  According to a fifth aspect of the present invention, in the fuel cutoff valve diagnosis device according to any one of the second to fourth aspects, the predetermined value for the cumulative value of the consumption amount of the gas fuel is determined by closing the cutoff valve. After that, the gist is that the value is set such that the operation of the engine can be maintained only by the fuel remaining on the engine side from the shutoff valve.

  According to such a configuration, even when the amount of fuel consumed by the engine is large, it is possible to reliably prevent a shortage of fuel supply to the engine during diagnosis. Thereby, according to this fuel cutoff valve diagnostic device, even if the fuel consumption of the engine is large, the valve function of the cutoff valve can be diagnosed while minimizing the influence on the operation of the engine.

  According to a sixth aspect of the present invention, in the fuel shut-off valve diagnostic device according to any one of the second to fifth aspects, the closing of the shut-off valve causes a shortage of gas fuel injected and supplied to the engine. The gist is that the fuel pressure is stopped when the fuel pressure falls below the set stop pressure.

  According to such a configuration, even if the fuel pressure suddenly drops, the diagnosis of the valve function is stopped when the fuel pressure is lower than the stop pressure, so the shut-off valve is opened. The fuel supply to the engine can be resumed. As a result, the influence of the diagnosis of the valve function of the shut-off valve by the fuel shut-off valve diagnostic device on the operation of the engine can be reduced.

  According to a seventh aspect of the present invention, in the fuel shut-off valve diagnosis device according to the sixth aspect, the diagnosis of the shut-off valve is normal on the condition that the fuel pressure is equal to or lower than the pressure determination value. The gist.

  According to such a configuration, when the shutoff valve closes normally, the diagnosis that the valve function is normal can be completed within a short time. This also makes it possible to suppress the influence of the diagnosis of the valve function of the cutoff valve by the fuel cutoff valve diagnostic device on the operation of the engine.

  The invention according to claim 8 is the fuel shut-off valve diagnosis device according to claim 6 or 7, wherein the pressure determination value is a value obtained by calculating the fuel pressure when the shut-off valve is open and the stop pressure. The gist is to be set in between.

  According to such a configuration, it is possible to appropriately determine whether or not the shut-off valve is closed normally, and to cope with a sudden drop in fuel pressure. The influence of the diagnosis of the valve function on the engine operation can be reduced.

  The invention according to claim 9 is the fuel shut-off valve diagnostic device according to any one of claims 1 to 8, wherein the gas fuel is compressed natural gas, and is between the fuel tank and the engine. Is provided with a pressure regulator for adjusting the fuel pressure of the gas fuel supplied from the fuel tank to a pressure suitable for the injection supply to the engine, and the pressure sensor is provided between the shut-off valve and the pressure regulator. The gist is that it is provided.

  According to such a configuration, the valve function of the shut-off valve is diagnosed based on the fuel pressure in the fuel tank that is higher than the pressure supplied to the engine. There is less risk that the fuel pressure of the gas fuel will be lower than the pressure supplied to the engine. Thereby, the influence which the diagnosis of the valve function of the shut-off valve by such a fuel shut-off valve diagnostic device has on the operation of the engine can be suppressed.

  In addition, since it is possible to ensure a wide range of fuel pressure that can be used for diagnosis, improvement in diagnosis accuracy and stabilization are also expected.

The block diagram which shows the schematic structure about 1st Embodiment which actualized the fuel supply apparatus provided with the fuel cutoff valve diagnostic apparatus which concerns on this invention. FIG. 3 is a time chart showing diagnosis by the fuel shut-off valve diagnostic device of the embodiment, where (a) is a time chart when the fuel consumption of the engine is large, and (b) is a time chart when the fuel consumption of the engine is small. . The flowchart which shows the diagnostic procedure by the fuel cutoff valve diagnostic apparatus of the embodiment. The time chart which shows the example of a diagnosis by the fuel cutoff valve diagnostic apparatus of the embodiment. The time chart which shows the example of a diagnosis about 2nd Embodiment which actualized the fuel cutoff valve diagnostic apparatus which concerns on this invention. The flowchart which shows the diagnostic procedure by the fuel cutoff valve diagnostic apparatus of the embodiment. It is a time chart which shows the example of a diagnosis by the conventional fuel cutoff valve diagnostic apparatus, (a) is a time chart when the fuel consumption of an engine is large, (b) is a time chart when the fuel consumption of an engine is small.

(First embodiment)
Hereinafter, a first embodiment in which a fuel supply device having a fuel cutoff valve diagnosis device of the present invention is embodied as a fuel supply device for an internal combustion engine using compressed natural gas (CNG) as fuel will be described with reference to FIGS. To do. This fuel supply device is mounted on the vehicle 1A.

  An engine 1 as an internal combustion engine shown in FIG. 1 is driven by injecting and supplying CNG as fuel (gas fuel) from an injector 2 and combusting the CNG. When the engine 1 is driven, the rotation of the crankshaft, which is the output shaft, is transmitted to the drive system to drive the vehicle 1A.

  The fuel supply device of the engine 1 is for supplying CNG to a delivery pipe 4 connected to the injector 2. This fuel supply device includes a first supply pipe 7A connected to the fuel tank 5, a second supply pipe 7B connected to the delivery pipe 4, a first supply pipe 7A, and a second supply pipe 7B. And a pressure regulator 6 disposed between the two. In the fuel supply apparatus, the first and second supply pipes 7A and 7B, the delivery pipe 4, the pressure regulator 6 and the like constitute fuel pipes for supplying CNG in the fuel tank 5 to the engine 1. Has been.

The first supply pipe 7 </ b> A and the second supply pipe 7 </ b> B are pipes for supplying the delivery pipe 4 with fuel made of CNG stored in the fuel tank 5.
The pressure regulator 6 is a pressure regulator that adjusts the pressure of the CNG supplied from the first supply pipe 7A to the second supply pipe 7B, so-called fuel pressure, to a predetermined pressure. The pressure regulator 6 is a predetermined pressure (for example, 1 MPa or 0. 4MPa) and supplied to the delivery pipe 4 via the second supply pipe 7B. Thereby, the pressure of CNG in the second supply pipe 7 </ b> B and the delivery pipe 4 is maintained in a predetermined pressure range by the pressure regulator 6.

  At the end of the first supply pipe 7A on the fuel tank 5 side (upstream side), a fuel cutoff that closes and opens the valve to prohibit / permit the outflow of CNG from the fuel tank 5 to the first supply pipe 7A. A shut-off valve 9 is provided as a valve. That is, when the shutoff valve 9 is closed, the first supply pipe 7A is shut off from the fuel tank 5, and the fuel is supplied from the fuel tank 5 to the delivery pipe 4 via the first and second supply pipes 7A and 7B. Supply is stopped. On the other hand, when the shut-off valve 9 is opened, the first supply pipe 7A communicates with the fuel tank 5, and fuel is supplied from the fuel tank 5 to the delivery pipe 4 via the first and second supply pipes 7A and 7B. Is done. For example, the shutoff valve 9 is fully opened to allow CNG to flow out from the fuel tank 5 to the first supply pipe 7A during engine operation, and from the fuel tank 5 to the first supply pipe 7A when the engine is stopped. In order to prohibit unnecessary CNG outflow, the valve is fully closed. In addition, as such a shutoff valve 9, it is possible to employ | adopt an electromagnetic valve. When a solenoid valve is used as the shutoff valve 9, the shutoff valve 9 is opened / closed (open / closed) through voltage application to the solenoid solenoid of the shutoff valve 9.

  A fuel pressure sensor 8 constituting a fuel shutoff valve diagnostic device is disposed on the pressure regulator 6 side of the first supply pipe 7A, and the fuel pressure sensor 8 causes the CNG pressure (fuel) in the first supply pipe 7A to be measured. Pressure) is detected. The pressure of CNG detected by the fuel pressure sensor 8 is also detected as the remaining amount of CNG.

Next, the electrical configuration of the fuel supply device will be described.
The fuel supply device is provided with an electronic control device 10 that constitutes a fuel cutoff valve diagnostic device. The electronic control device 10 is mainly configured by a microcomputer provided with an arithmetic device (CPU) and a storage device (ROM and RAM). The electronic control unit 10 executes various arithmetic processes related to the control of the engine 1 by the CPU, stores programs and data necessary for the control in the ROM, and temporarily stores the calculation results of the CPU in the RAM. . The electronic control device 10 is configured to include an input / output port for inputting / outputting a signal to / from the outside.

Various sensors shown below are connected to the input port of the electronic control unit 10.
A crank position sensor that outputs a signal corresponding to the rotation of the crankshaft of the engine 1.

A fuel pressure sensor 8 that detects the fuel pressure in the fuel tank 5 (specifically, the first fuel pipe 7A).
On the other hand, the output port of the electronic control device 10 is connected to the drive circuit of the injector 2 and the shutoff valve 9.

  Then, the electronic control unit 10 grasps the engine rotation state, the pressure state of the fuel in the fuel supply system, and the like based on the detection signals input from the respective sensors, and variously connected to the output port according to them. A command signal is output to the drive circuit. Thus, drive control of the injector 2 and the shutoff valve 9 is performed through the electronic control device 10.

  For example, the electronic control unit 10 calculates a fuel injection amount to be injected to the injector 2 based on the engine rotation state and the like, and controls the drive of the injector 2 based on the calculated injection amount. Further, the electronic control unit 10 causes the injector 2 to inject even if the crankshaft of the engine 1 is rotating when the engine brake is operated or the low fuel consumption control for improving the fuel efficiency is performed. A so-called fuel cut may be performed in which the fuel injection amount is set to “0”.

  Further, the electronic control unit 10 according to the present embodiment diagnoses the valve function of the shut-off valve 9 to determine whether the shut-off valve 9 is open or closed, for example, the valve is open or cannot be closed completely. Diagnose poor valve closing. For this reason, the electronic control device 10 is set with a program, parameters, and the like for diagnosing the valve function of the shutoff valve 9. The defective valve closing of the shut-off valve 9 includes a defect caused by any cause. For example, a malfunction of the valve due to the viscosity of the oil component contained in the CNG, so-called valve sticking, or a seal in which a gap is formed between the valve closed by the oil component adhering to the seal surface of the valve and the seal surface It also includes a failure, a mechanical failure of the valve mechanism, an operation failure of the electromagnetic solenoid that drives the shut-off valve 9, and an electrical failure such as a short circuit.

  As shown in FIG. 2, the electronic control unit 10 includes, as the above-described parameters, an accumulated fuel consumption amount of the engine 1, a consumption threshold value FT that is used for determining the end of diagnosis, and a fuel pressure in the delivery pipe 4. A lower limit pressure PB is set as a stop pressure, which is the minimum value of the pressure that can be maintained at a predetermined pressure suitable for fuel injection from 2. The consumption threshold FT is set to a value that allows the operation of the engine 1 to be maintained only with the gas fuel remaining on the engine 1 side from the shut-off valve 9 after the shut-off valve 9 is closed. In addition, the electronic control unit 10 determines whether the valve function of the shut-off valve 9 is normal or abnormal by comparing with a diagnosis start pressure PA, which is a fuel pressure at the start of diagnosis, or a fuel pressure measured at the end of the diagnosis. A diagnostic threshold PT is set as a pressure determination value that can be determined on one side. The diagnosis threshold value PT is set as a value between the diagnosis start pressure PA and the lower limit pressure PB. That is, the diagnosis start pressure PA is higher than the diagnosis threshold value PT, while the lower limit pressure PB is a diagnosis value. The pressure is lower than the threshold value PT. By the way, since the diagnosis start pressure PA changes according to the remaining amount of CNG, the electronic control device 10 stores map data from which the diagnostic threshold value PT can be acquired according to the remaining amount of CNG. That is, in the map data, when CNG is consumed by the consumption threshold value FT at each CNG pressure, the valve function of the shut-off valve 9 is set appropriately based on the pressure drop amount Δ1 (Δ2) that the consumption threshold value FT causes in the CNG pressure. The threshold value for diagnosis PT that can be determined is set separately for the CNG pressure. Further, the diagnosis start pressure PA is limited to a pressure that does not reach the lower limit pressure PB even if the fuel pressure is reduced by the pressure drop amount Δ1 (Δ2). The diagnosis threshold PT may be calculated according to the diagnosis start pressure PA.

  For example, as shown in FIG. 2A, when the electronic control unit 10 starts diagnosis of the valve function of the shutoff valve 9 at the start time T1s, the fuel injection from the injector 2 calculated based on the drive control of the injector 2 is performed. A cumulative value obtained by accumulating the amount is set as a cumulative fuel consumption amount F1 of the engine 1. That is, the electronic control unit 10 monitors the accumulated fuel consumption amount F1 of the engine 1. Then, the electronic control unit 10 measures the fuel pressure P1 on the condition that the accumulated fuel consumption amount F1 reaches the end time T1e at which the cumulative fuel consumption amount F1 is equal to or greater than the consumption amount threshold value FT. The electronic control unit 10 compares and determines whether the measured fuel pressure P1 is higher or lower than the diagnostic threshold value PT. If the measured fuel pressure P1 is higher, the electronic control unit 10 determines that an abnormality has occurred in the closing of the shut-off valve 9. It is determined that the valve closing function of the valve 9 is normal. That is, if the fuel pressure P1 is higher than the diagnostic threshold PT, it is determined that gas fuel is supplied from the fuel tank 5 through the shut-off valve 9 even though the shut-off valve 9 is closed. Therefore, it is determined that an abnormality in which the shut-off valve 9 is not completely closed, that is, an open sticking or a valve closing failure has occurred.

  2B shows a case where the time required for diagnosis (from time T2s to time T2e) is longer than the time required for diagnosis in the case of FIG. 2A (from time T1s to time T1e). Show. That is, as shown in FIG. 2B, when the fuel consumption of the engine 1 is smaller than that in FIG. 2A, the electronic control unit 10 diagnoses the valve function of the shutoff valve 9 at the start time T2s. When the operation starts, the fuel injection amount from the injector 2 is accumulated in the same manner as described above, and the accumulated fuel injection amount is set as the accumulated fuel consumption amount F2. Then, the electronic control unit 10 compares the accumulated fuel consumption amount F2 with the consumption amount threshold value FT, and measures the fuel pressure P2 on the condition that the accumulated fuel consumption amount F2 becomes an end time T2e that is equal to or greater than the consumption amount threshold value FT. The electronic control unit 10 compares and determines whether the measured fuel pressure P2 is higher or lower than the diagnostic threshold value PT. If the measured fuel pressure P2 is higher, the electronic control unit 10 determines that the above-described abnormality occurs in the closing of the shutoff valve 9. On the other hand, if it is low, it is determined that the valve function of the shut-off valve 9 is normal.

  As described above, the electronic control device 10 determines the fuel pressure P1 (P2) because the diagnostic time from the start time T1s (T2s) to the end time T1e (T2e) is defined by the accumulated fuel consumption F1 (F2). Regardless of the fuel consumption of the engine 1 that changes from time to time, only a decrease in fuel pressure corresponding to the cumulative fuel consumption F1 (F2) occurs. For example, if the fuel pressure P1 (P2) at the start time T1s (T2s) is the same, the pressure drop Δ1 (Δ2) that decreases during the diagnosis time is the same regardless of the amount of fuel consumption of the engine 1. Therefore, the fuel pressure P1 (P2) at the end time T1e (T2e) has the same value. Therefore, when the fuel consumption is large, the cumulative fuel consumption F1 reaches the consumption threshold value FT in a short time, and the fuel pressure P1 at the diagnosis end time T1e is obtained in a short diagnosis time. The obtained fuel pressure The valve function of the shut-off valve is determined by comparing P1 with the diagnostic threshold PT. On the contrary, when the fuel consumption is small, the diagnosis is continued until the cumulative fuel consumption F2 reaches the consumption threshold FT, and the fuel pressure P2 is obtained by setting the time when the consumption threshold FT is reached as the diagnosis end time T2e. The obtained fuel pressure P2 is compared with the diagnostic threshold value PT to determine the valve function of the shutoff valve. In any case, when the fuel pressure P1 (P2) becomes lower than the lower limit pressure PB during diagnosis of the valve function of the shutoff valve 9, the diagnosis is stopped and the shutoff valve 9 is opened to open the engine 1 It is possible to prevent a shortage of fuel to be supplied.

  In addition, since the capacity | capacitance in fuel piping which consists of capacity | capacitance in the 1st supply piping 7A etc. when the cutoff valve 9 closes is fixed, the pressure which falls when gas fuel is consumed only by consumption threshold value FT. A decrease amount Δ1 (Δ2) is determined, and is set in advance so that the pressure decrease amount Δ1 (Δ2) does not decrease below the lower limit pressure PB.

Next, the operation (action) of the fuel supply device will be described with reference to FIG.
In the present embodiment, diagnosis of the valve function of the shut-off valve 9 is started at appropriate times based on a predetermined time interval, a predetermined vehicle condition, and the like. The diagnosis of the valve function of the shutoff valve 9 may be executed when there is a margin in the arithmetic processing of the electronic control device 10.

  As shown in FIG. 3, when the diagnosis of the valve function of the shutoff valve 9 is started, the electronic control unit 10 determines whether or not the fuel pressure P1 is equal to or higher than the diagnosis start pressure PA (step S10). The diagnosis start pressure PA is higher than the diagnosis threshold PT. When it is determined that the fuel pressure P1 is not equal to or higher than the diagnosis start pressure PA (NO in step S10), the electronic control unit 10 ends the diagnosis of the valve function of the shutoff valve 9. On the other hand, when it is determined that the fuel pressure P1 is equal to or higher than the diagnosis start pressure PA (YES in step S10), the electronic control unit 10 closes the shutoff valve 9 (step S11) and measures the fuel pressure P1. (Step S12). Then, the electronic control unit 10 determines whether or not the accumulated fuel consumption amount F1 is greater than or equal to the consumption threshold value FT (step S13). When it is determined that the cumulative fuel consumption F1 is not equal to or greater than the consumption threshold FT (NO in step S13), the electronic control unit 10 returns to step S12 at a predetermined interval and measures the fuel pressure P1 again (step). At the same time as S12), it is determined whether or not the cumulative fuel consumption F1 is equal to or greater than the consumption threshold FT (Step S13).

  On the other hand, when it is determined that the accumulated fuel consumption F1 is equal to or greater than the consumption threshold FT (YES in step S13), the electronic control unit 10 determines whether or not the fuel pressure P1 measured last is equal to or less than the diagnostic threshold PT. Is determined (step S14). When it is determined that the last measured fuel pressure P1 is less than or equal to the diagnostic threshold PT (YES in step S14), the electronic control unit 10 determines that the shut-off valve 9 has been normally closed (step S15). At the same time, the shutoff valve 9 is opened (step S16), and the diagnosis of the valve function of the shutoff valve 9 is terminated. Conversely, if it is determined that the last measured fuel pressure P1 is not less than or equal to the diagnostic threshold PT (NO in step S14), the electronic control unit 10 determines that the shut-off valve 9 is not closed. Simultaneously with (step S17), the shut-off valve 9 is opened (step S16), and the diagnosis of the valve function of the shut-off valve 9 is ended.

  Further, according to such a fuel supply device, even when engine control (low fuel consumption control) such as fuel cut for improving fuel efficiency is performed during diagnosis of the valve function of the cutoff valve 9, the cutoff valve Diagnosis of 9 valve functions can be performed appropriately.

  That is, as shown in FIG. 4, the fuel cut is performed between time C11 and time C12 after the valve function diagnosis is started at the start time T3s and before the cumulative fuel consumption F3 reaches the consumption threshold FT. When it is performed, the cumulative fuel consumption F3 does not increase from the time C11 to the time C12. As a result, although the time required for the diagnosis of the valve function becomes longer, the engine 1 does not consume fuel, so there is no shortage of fuel supply. That is, although the shutoff valve 9 is closed, the fuel pressure P3 is also kept constant, so that there is no inconvenience in the fuel supply.

  When the fuel cut is completed at time C12, the cumulative fuel consumption amount F3 increases to reach the consumption threshold value FT, and the fuel pressure P3 at the end time T3e when the consumption threshold value FT is reached is measured. At this time, although it took a long time to diagnose the valve function, the decrease in the pressure relative to the diagnosis start pressure PA is the same fuel decrease amount Δ3 as when the fuel is not cut. Then, the valve function is diagnosed by comparing the measured fuel pressure P3 with the diagnostic threshold value PT. As described above, since the end time T3e is determined by the consumption threshold value FT, the influence of the valve function of the shut-off valve 9 can be minimized while minimizing the influence of time constraints for diagnosis and constraints on operation control of the engine 1. Diagnosis can be made.

As described above, according to the fuel supply device having the fuel cutoff valve diagnostic device of the present embodiment, the effects listed below can be obtained.
(1) After the shut-off valve 9 is closed, a consumption amount in which the cumulative fuel consumption (F1) of the gas fuel remaining between the shut-off valve 9 injected and supplied to the engine 1 and the engine 1 is a predetermined value When the threshold value FT is reached, the valve function of the shut-off valve 9 is determined. As a result, the consumption threshold value FT required for determining the valve function of the shut-off valve 9 can be quantified, so that a diagnosis that is not influenced by the amount of fuel consumption of the engine 1 can be performed. At this time, the consumption threshold value FT is set to an appropriate value corresponding to the amount of gas fuel remaining between the shut-off valve 9 and the engine 1, particularly the amount accommodated in the first supply pipe 7A. Then, when the fuel consumption by the engine 1 is large, the fuel supply to the engine 1 is insufficient during the diagnosis, and conversely, when the fuel consumption is small, the decrease in the fuel pressure is reduced. This prevents the function from being diagnosed appropriately. Further, the diagnosis of the valve function of the shut-off valve 9 is performed in a short time when the fuel consumption by the engine 1 is large. On the other hand, when the fuel consumption is small, the necessary time is secured. That is, the time required for diagnosing the valve function of the shutoff valve is appropriately adjusted according to the fuel consumption of the engine.

Thus, according to this fuel cutoff valve diagnostic device, the valve function of the cutoff valve 9 can be properly diagnosed regardless of the amount of fuel consumption of the engine 1.
(2) Fuel passing through the diagnosis if the fuel pressure (P1, P2) when the valve function of the shut-off valve 9 is open is reduced by closing and the valve function is normal. The pressure threshold is defined as a diagnostic threshold PT. If such a diagnostic threshold value PT is set, it becomes possible to diagnose the presence or absence of a valve closing failure such as valve sticking depending on whether or not the fuel pressure drops to the diagnostic threshold value PT.

  (3) Since the fuel pressure (P1, P2) is higher than the diagnostic threshold PT, the shut-off valve 9 has a malfunction in the valve closing function such as the valve opening sticking that remains open (the valve closing defect). Diagnose that That is, since the fuel pressure is higher than the diagnostic threshold value PT, it is determined that the gas fuel is supplied from the fuel tank 5 through the shut-off valve 9 even though the shut-off valve 9 is closed. It is detected that the valve 9 is not completely closed, that is, the valve is not closed properly such as open sticking.

  (4) Since the fuel pressure (P1, P2) is higher than the diagnostic threshold value PT when the shut-off valve 9 is closed, the fuel pressure (P1, P2) is reduced by the decrease of the fuel pressure (P1, P2) due to the valve closing. Approaches the diagnostic threshold PT. Thereby, the quality of the valve closing function of the shutoff valve 9 can be diagnosed by comparison with the diagnostic threshold value PT.

  (5) Since the consumption threshold value FT is set to a value that can maintain the operation of the engine 1 only with the fuel remaining on the engine 1 side from the shut-off valve 9, it is possible to diagnose even when the fuel consumption by the engine 1 is large. Insufficient fuel supply to the engine 1 can be reliably prevented. Thereby, according to this fuel cutoff valve diagnostic device, even if the fuel consumption of the engine 1 is large, the valve function of the cutoff valve can be diagnosed while minimizing the influence on the operation of the engine.

  (6) Even if the fuel pressure is suddenly lowered by setting the lower limit pressure PB for stopping the diagnosis, the diagnosis of the valve function is stopped when the fuel pressure becomes lower than the lower limit pressure PB. Therefore, the fuel supply to the engine 1 can be resumed by opening the shutoff valve 9. Thereby, the influence which the diagnosis of the valve function of the shut-off valve 9 by this fuel shut-off valve diagnostic device has on the operation of the engine 1 can be suppressed.

  (7) A diagnostic threshold PT is set between the fuel pressure (starting pressure PA) and the lower limit pressure PB when the shutoff valve 9 is open. From this, it is possible to appropriately determine whether or not the shut-off valve 9 is closed normally, and to cope with a sudden drop in fuel pressure (P1, P2). The influence of the diagnosis of the valve function of the shut-off valve 9 on the operation of the engine 1 can be reduced.

  (8) By providing the fuel pressure sensor 8 in the first supply pipe 7A, the valve function of the shutoff valve 9 is diagnosed based on the fuel pressure in the fuel tank 5 that is higher than the pressure supplied to the engine 1. Therefore, the fuel pressure of the gas fuel supplied to the engine 1 during diagnosis is less likely to be lower than the pressure supplied to the engine 1. Thereby, the influence which the diagnosis of the valve function of the cutoff valve 9 by such a fuel cutoff valve diagnostic apparatus has on the operation of the engine 1 can be suppressed.

In addition, since it is possible to ensure a wide range of fuel pressure that can be used for diagnosis, improvement in diagnosis accuracy and stabilization are also expected.
(Second Embodiment)
A second embodiment embodying a fuel supply apparatus having a fuel cutoff valve diagnostic apparatus according to the present invention will be described with reference to FIGS.

  This embodiment is the same in other configurations, although a part of the procedure for diagnosis of the valve function of the shut-off valve 9 is different from the procedure of the first embodiment. Therefore, in the present embodiment, the differences will be mainly described, and for the sake of convenience of explanation, the same reference numerals will be given to the same configurations as in the first embodiment, and the detailed description thereof will be omitted.

  As shown in FIG. 5, the fuel cut is performed between the time C21 and the time C22 after the valve function diagnosis is started at the start time T4s and before the cumulative fuel consumption F4 reaches the consumption threshold FT. The accumulated fuel consumption F4 does not increase during the time C21 to the time C22. When the fuel cut is completed at time C22, at time T4e before the cumulative fuel consumption F4 increases and reaches the consumption threshold FT, the fuel pressure P4 decreases by the pressure decrease amount Δ4 and the diagnostic threshold PT To reach. At this time, in this embodiment, the measured fuel pressure P4 is compared with the diagnostic threshold value PT, and since the fuel pressure P4 is equal to or lower than the diagnostic threshold value PT, it is determined that the cutoff valve 9 is normally closed. The diagnosis of the valve function 9 is terminated.

  At this time, even if the diagnosis of the valve function of the shutoff valve 9 is continued after time T4e, the measured fuel pressure P4 is less than or equal to the diagnostic threshold PT, although the pressure drop amount Δ4 increases. Therefore, it may be diagnosed that the shutoff valve 9 is normally closed at time T4e. As described above, when the shutoff valve 9 is normal, the diagnosis is completed at the time T4e, so that the diagnosis is performed when the accumulated fuel consumption amount F4 reaches the consumption threshold value FT. Thus, the time required for diagnosing the valve function of the shut-off valve 9 can be shortened.

Next, the operation (action) of the fuel supply device will be described with reference to FIG.
As shown in FIG. 6, when the diagnosis of the valve function of the shutoff valve 9 is started, the electronic control unit 10 determines whether or not the fuel pressure P4 is equal to or higher than the diagnosis start pressure PA (step S20). When it is determined that the fuel pressure P4 is not equal to or higher than the diagnosis start pressure PA (NO in step S20), the electronic control unit 10 ends the diagnosis of the valve function of the shutoff valve 9. On the other hand, when it is determined that the fuel pressure P4 is equal to or higher than the diagnosis start pressure PA (YES in step S20), the electronic control unit 10 closes the shut-off valve 9 (step S21) and measures the fuel pressure P4. (Step S22).

  Then, the electronic control unit 10 determines whether or not the last measured fuel pressure P4 is less than or equal to the diagnostic threshold PT (step S23). When it is determined that the last measured fuel pressure P4 is less than or equal to the diagnostic threshold PT (YES in step S23), the electronic control unit 10 determines that the closing of the shutoff valve 9 is normal (step S24). In addition, the shutoff valve 9 is opened (step S25), and the diagnosis of the valve function of the shutoff valve 9 is completed.

  On the other hand, when it is determined that the last measured fuel pressure P4 is not less than or equal to the diagnostic threshold PT (NO in step S23), the electronic control unit 10 determines whether or not the cumulative fuel consumption F4 is greater than or equal to the consumption threshold FT. Is determined (step S26). If it is determined that the cumulative fuel consumption F4 is not equal to or greater than the consumption threshold FT (NO in step S26), the electronic control unit 10 returns to step S22 after a predetermined interval and measures the fuel pressure P4 again (step S26). The subsequent steps are repeated together with S22). Conversely, if it is determined that the last measured fuel pressure P4 is equal to or less than the diagnostic threshold value PT (YES in step S26), the electronic control unit 10 determines that the shutoff valve 9 is not closed properly. (Step S27), the shut-off valve 9 is opened (Step S25), and the diagnosis of the valve function of the shut-off valve 9 is completed.

  As described above, according to the fuel supply device having the fuel cutoff valve diagnostic device of the present embodiment, in addition to the effects (1) to (8) described in the first embodiment, the following is listed. The effect which does.

  (9) When the shutoff valve 9 closes normally, the diagnosis that the valve function is normal can be completed within a short time. This also makes it possible to reduce the influence of the diagnosis of the valve function of the shut-off valve 9 by the fuel shut-off valve diagnostic device on the operation of the engine 1.

(Other embodiments)
In addition, each said embodiment can also be implemented with the following aspects.
In each of the above embodiments, the present invention may be applied to the fuel supply device of the engine 1 that uses liquefied petroleum gas (LPG) or gasoline as the fuel. In the case of a device that supplies pressurized fuel to the injector 2, the fuel pressure in the fuel pipe is lowered by closing the shutoff valve to stop the fuel supply from the fuel tank to the engine. The quality of the shut-off valve can be judged.

  In each of the above embodiments, the case where the consumption threshold value FT is constant is illustrated, but may be changed according to the diagnosis start pressure or the like. This makes it possible to appropriately adjust the time and accuracy required for the diagnosis of the valve function.

  In each of the above embodiments, the case where the shut-off valve 9 is provided in the first supply pipe 7A has been illustrated. However, the present invention is not limited thereto, and the shut-off valve is provided between the fuel tank and the pressure regulator. Good. For example, the shut-off valve may be attached to the fuel tank or may be internally provided. Thereby, the freedom degree of a structure of such a fuel cutoff valve diagnostic apparatus is raised.

  In each of the above embodiments, the case where the cumulative fuel consumption of the fuel supplied to the engine 1 is obtained by accumulating the fuel injection amount from the injector 2 has been illustrated. However, the present invention is not limited to this, and the accumulated fuel consumption may be calculated based on a flow rate measured or calculated downstream of the pressure regulator. Thereby, the freedom degree of a structure of such a fuel cutoff valve diagnostic apparatus is raised.

  DESCRIPTION OF SYMBOLS 1 ... Engine, 1A ... Vehicle, 2 ... Injector, 4 ... Delivery pipe, 5 ... Fuel tank, 6 ... Pressure regulator, 7A ... 1st supply piping, 7B ... 2nd supply piping, 8 ... Fuel pressure sensor, 9 ... shutoff valve, 10 ... electronic control unit, F1, F2, F3, F4 ... cumulative fuel consumption, FT ... consumption threshold, P1, P2, P3, P4 ... fuel pressure, PA ... diagnosis start pressure, PB ... lower limit pressure , PT ... diagnostic threshold, Te, T1e, T2e, T3e, T4e ... end time, Ts, T1s, T2s, T3s, T4s ... start time.

Claims (9)

Based on the fuel pressure detected by a pressure sensor provided between the fuel tank and the engine, the valve function of a shutoff valve that permits or prohibits the supply of gas fuel from the fuel tank to the engine by opening and closing the valve. A fuel cutoff valve diagnostic device for diagnosing,
The shut-off valve is closed during operation of the engine, and the consumption of gas fuel injected and supplied to the engine is monitored from when the shut-off valve is closed. A fuel shut-off valve diagnosis device characterized by diagnosing the valve function of the shut-off valve on condition that a predetermined value is reached. Diagnosis of the valve function of the shut-off valve compares the fuel pressure detected when the accumulated value of the consumption amount of the gas fuel reaches the predetermined value with a pressure determination value capable of determining the presence or absence of valve closing failure. The fuel cutoff valve diagnostic device according to claim 1, wherein The fuel cutoff valve diagnosis device according to claim 2, wherein when the detected fuel pressure is higher than the pressure determination value, the cutoff valve is diagnosed as having a valve closing failure. The fuel cutoff valve diagnosis device according to claim 2 or 3, wherein the diagnosis of the valve function of the cutoff valve is started on condition that the fuel pressure is higher than the pressure determination value. The predetermined value for the cumulative value of the consumption amount of the gas fuel is set to a value that can maintain the operation of the engine only with the fuel remaining on the engine side from the cutoff valve after the cutoff valve is closed. The fuel cutoff valve diagnostic device according to any one of claims 2 to 4. The fuel according to any one of claims 2 to 5, wherein the shut-off valve is closed when the gas pressure supplied to the engine is less than a stop pressure set as a fuel pressure that does not cause a shortage. Shut-off valve diagnostic device. The fuel cutoff valve diagnosis device according to claim 6, wherein the cutoff valve is diagnosed as being normal on the condition that the fuel pressure is equal to or lower than the pressure determination value. The fuel cutoff valve diagnosis device according to claim 6 or 7, wherein the pressure determination value is set between a fuel pressure when the cutoff valve is open and the stop pressure. The gas fuel is compressed natural gas;
A pressure regulator is provided between the fuel tank and the engine to adjust the fuel pressure of the gas fuel supplied from the fuel tank to a pressure suitable for injection supply to the engine,
The fuel cutoff valve diagnosis device according to any one of claims 1 to 8, wherein the pressure sensor is provided between the cutoff valve and the pressure regulator.

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