JP6172469B2 - Abnormality judgment device for weight reduction valve - Google Patents

Description

  The present invention relates to a fuel injection valve, a pump for discharging fuel to a fuel supply path, and a reduction valve provided on the path for supplying all the fuel discharged from the pump to the fuel injection valve when the valve is closed and opening the valve. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a weight reduction valve abnormality determination device that is applied to a fuel system having a weight reduction valve that supplies a part of discharged fuel to a fuel injection valve by discharging a predetermined amount of fuel from the same path.

  Conventionally, a fuel system has been proposed in which a reduction valve is provided on a fuel supply path connecting a fuel injection valve and a pump. The reduction valve is an open / close valve that can discharge a predetermined amount of fuel passing through the supply path (in other words, a predetermined amount of fuel discharged from the pump) from the same path as necessary. Specifically, when the reduction valve is open, a predetermined amount is discharged from the fuel supply path via the reduction valve, and when the reduction valve is closed, the discharge does not occur. That is, the reduction valve supplies "a part" of the fuel discharged by the pump to the fuel injection valve when it is open, and supplies "the whole" of the same discharge fuel to the fuel injection valve when it is closed. .

  By using the reduction valve, for example, the amount of fuel discharged from the pump (pump discharge) while supplying the fuel required by the fuel injection valve (required amount of fuel in the fuel injection valve) to the injection valve. Amount) can be increased or decreased. Specifically, when the reduction valve is closed, all of the discharged fuel is supplied to the fuel injection valve. Therefore, if the pump is instructed to discharge the same amount as the required amount, the required amount of fuel is supplied to the fuel injection valve. Can supply. On the other hand, when the reduction valve is opened, a part of the discharged fuel is supplied to the fuel injection valve. Therefore, the pump discharges an amount obtained by adding a predetermined amount (discharge amount) discharged through the reduction valve to the required amount. The required amount of fuel can be supplied to the fuel injection valve. That is, by opening and closing the reduction valve, the discharge amount can be switched between “request amount” and “total of request amount and discharge amount” while maintaining the request amount.

  For example, in a conventional fuel system, when the discharge amount instructed to the pump is smaller than the lower limit discharge amount of the pump because the required amount of the fuel injection valve is small, the reduction valve is opened and the required amount and the discharge amount are discharged. The pump is instructed to discharge the sum of the quantity. That is, in this case, the fuel system increases the discharge amount instructed to the pump by the discharge amount. Thereby, this fuel system can supply the required amount of fuel to the fuel injection valve even when the required amount of the fuel injection valve is smaller than the lower limit discharge amount of the pump (see, for example, Patent Document 1). ).

JP 2013-231373 A

  The weight reducing valve generally has a mechanical opening / closing mechanism, and may be fixed to a peripheral member in an open state or a closed state due to deterioration over time or the like. For example, when the reduction valve is stuck in an open state, the reduction valve cannot be closed even if a closing instruction (close instruction) is given to the reduction valve. On the other hand, when the reduction valve is fixed in a closed state, the reduction valve cannot be opened even if a valve opening instruction (open instruction) is given to the reduction valve. Hereinafter, the former is referred to as “open sticking abnormality”, and the latter is referred to as “closed sticking abnormality”.

  When a fuel system including a reduction valve is applied to an internal combustion engine (hereinafter referred to as “engine”), the above-described abnormality is an air-fuel ratio control of the engine (for example, a feedback amount for making the air-fuel ratio coincide with a target value) Parameter). For example, when an “open sticking abnormality” occurs, even if the instruction to the reduction valve changes from opening to closing, the reduction valve does not actually close. On the other hand, the discharge amount of the pump is switched on the assumption that the reduction valve is closed (that is, it is reduced by the discharge amount). Therefore, the pump discharge amount is insufficient with respect to the required amount of the fuel injection valve, and the pressure of the fuel supplied to the fuel injection valve (hereinafter referred to as “fuel pressure”) decreases. As a result, unintended changes occur in the fuel injection amount and injection state (degree of diffusion, etc.), and the above parameters fluctuate. That is, the parameter varies due to the abnormality of the weight reducing valve. In other words, it can be considered that it can be determined (diagnostic) whether or not the weight reduction valve is abnormal based on the fluctuation of the parameter.

  However, parameters related to engine air-fuel ratio control are generally affected not only by the influence of the reducing valve but also by other members (for example, various members belonging to the intake system of the engine). Therefore, even if an unintended change occurs in the same parameter, it is difficult to specify whether the change is caused by an abnormality of the weight reduction valve or an abnormality of another member. In other words, it is difficult to distinguish and determine whether or not the weight reduction valve is abnormal and whether or not other members are abnormal.

  The objective of this invention is providing the abnormality determination apparatus which can determine independently whether the weight reduction valve is abnormal.

An apparatus for determining an abnormality of a weight reduction valve according to the present invention for solving the above problems is as follows.
An “injection valve” that injects fuel, a “pump” that discharges fuel to a supply path connected to the injection valve, and a reduction valve that is provided on the supply path. A "reduction valve" for supplying a part of the discharged fuel to the injection valve by supplying all of the fuel to the injection valve and discharging a predetermined amount of fuel from the supply path when the valve is opened; (Fuel system)

And the abnormality determination apparatus of this invention is
There is provided a “control unit” that gives an instruction to open or close the reducing valve, instructs the pump to discharge the amount, and determines whether or not the reducing valve is abnormal.

Here, the control unit relates to the discharge amount instructed to the pump,
“The required amount of fuel in the injection valve, the feedback amount in the feedback control for controlling the fuel pressure that is the pressure of the fuel supplied to the injection valve, and the discharge when the instruction to the reduction valve is open. The discharge amount is instructed to the pump so that the sum of the correction amount that is set to zero and the correction amount that is set to zero when the instruction to the reduction valve is closed is discharged.

Furthermore, the control unit relates to the determination of whether or not the weight reduction valve is abnormal,
As the “first abnormality determination”, when the condition that the instructed discharge amount is equal to or greater than the threshold discharge amount when the instruction to the reduction valve is closed is not established, the instruction to the reduction valve is Based on the difference between the feedback amount during the period when the valve is open and the feedback amount during the period when the instruction to the reduction valve is closed, it is determined whether or not the reduction valve is abnormal.
As the “second abnormality determination”, when the condition is satisfied, based on the transition of the fuel pressure when the instruction to the reduction valve is changed from closed to open while maintaining the correction amount at zero, It is configured to determine whether or not the weight reduction valve is abnormal.

  With the above configuration, the abnormality determination of the weight reduction valve is performed according to two types of abnormality determination methods (first abnormality determination or second abnormality determination). These abnormality determination methods are performed using a parameter (feedback amount or fuel pressure) that is linked to an instruction to the reduction valve (a valve opening instruction or a valve closing instruction). Furthermore, these parameters are parameters specific to the fuel system. Therefore, the abnormality determination device of the present invention can determine whether or not the weight reduction valve is abnormal, separately from the abnormality determination of other members.

  Details of the abnormality determination method (first abnormality determination and second abnormality determination) of the weight reduction valve according to the present invention will be described below.

First Abnormality Determination The “control unit” of the present invention “instructs the reduction valve to open or close and instructs the pump to discharge”. Specifically, the control unit gives an “opening or closing instruction” to the reduction valve as necessary. Further, the control unit is configured to provide the pump with “the required amount of fuel in the injection valve”, “the feedback amount in the feedback control for controlling the fuel pressure”, and “the discharge when the instruction to the reduction valve is open”. An instruction to discharge the sum of the “correction amount set to zero when the instruction to the reduction valve is closed” is set.

  However, the “feedback control” is a control that increases or decreases the discharge amount by the “feedback amount” so that the “fuel pressure” matches a predetermined target value. Furthermore, the “discharge amount” is an amount that is “discharged from the supply path” via the reduction valve when the reduction valve is opened (as a result, the amount of fuel actually supplied to the injection valve is reduced). The “predetermined” amount that can be specified in advance by an experiment or the like. The discharge amount may be a fixed value, or may be a variable value that takes into account the deterioration of the weight reducing valve over time. In addition, hereinafter, the discharge amount that the control unit instructs the pump is simply referred to as “discharge amount”.

  When the weight reduction valve is “normal”, when the valve closing instruction (close instruction) is given to the weight reduction valve, the weight reduction valve closes according to the instruction, so the amount discharged by the weight reduction valve (zero) and the “correction amount” "Matches" (zero if the instruction to the reduction valve is closed). Similarly, when a valve opening instruction (opening instruction) is given to the reducing valve, the reducing valve opens according to the instruction, so the amount discharged by the reducing valve (predetermined discharge amount) and the “correction amount” (to the reducing valve) If the instruction of the valve is closed, the same discharge amount) “matches”. Therefore, in this case, even if the discharge amount is increased or decreased in accordance with the change in the instruction to the reduction valve, the increase or decrease is offset by the opening and closing of the reduction valve, so that the fuel pressure does not change. Therefore, the feedback amount for controlling the fuel pressure does not change. In other words, the opening / closing of the reduction valve does not affect the feedback amount. As a result, in this case, “the feedback amount during the period when the instruction to the reduction valve is open” and “the feedback amount during the period when the instruction to the reduction valve is closed” are substantially (See also FIG. 3).

  On the other hand, if an “open sticking abnormality” occurs in the weight reduction valve, the amount that is actually discharged (weight reduction) because the weight reduction valve will not close even if a valve closing instruction (close instruction) is given to the weight reduction valve. The predetermined discharge amount (because the valve is stuck open) and the “correction amount” (zero assuming that the reduction valve is closed) are “not in agreement”. Therefore, the fuel pressure decreases with the instruction to close the valve, and the feedback amount increases so as to offset the decrease in fuel pressure. After that, when a valve opening instruction (opening instruction) is given to the reduction valve, the amount actually discharged (discharge amount) and the “correction amount” (discharge amount assuming that the reduction valve opens) are “Match”. Therefore, the feedback amount that has been increased returns to the original amount (decreases to the amount when the reduction valve is normal). Thus, in this case, the opening / closing of the reduction valve affects the feedback amount. As a result, “the feedback amount during the period when the instruction to the reduction valve is open” is different from “the feedback amount during the period when the instruction to the reduction valve is closed” ( (See also FIG. 3).

  In addition, when a “closed sticking abnormality” has occurred in the weight reduction valve, even if an instruction to open the valve (opening instruction) is given to the weight reduction valve, the weight reduction valve will not open. Zero (because it is closed and fixed) and “correction amount” (discharge amount on the assumption that the reduction valve opens) do not match. For this reason, the fuel pressure increases in accordance with the opening instruction, and the feedback amount decreases so as to offset the increase in fuel pressure. After that, when the closing instruction (closing instruction) is given to the reduction valve, the amount actually discharged (zero because the reduction valve is closed and fixed) and the "correction amount" (assuming that the reduction valve is closed) Zero) and “match”. Therefore, the feedback amount that has been reduced returns to the original amount (increases to the amount when the reduction valve is normal). Thus, in this case, the opening / closing of the reduction valve affects the feedback amount. As a result, “the feedback amount during the period when the instruction to the reduction valve is open” is different from “the feedback amount during the period when the instruction to the reduction valve is closed” ( (See also FIG. 3).

  As described above, when the “open sticking abnormality” or the “close sticking abnormality” occurs in the reduction valve, if the instruction to the reduction valve is different, the feedback amount is also different. Further, as can be understood from the above description, the difference in the feedback amount is caused by the abnormality of the reduction valve. Therefore, based on the “difference” between the feedback amounts described above, the abnormality determination of the reduction valve can be distinguished from the abnormality determination of other members. This is the “first abnormality determination” in the present invention.

  However, the first abnormality determination is that the pump can “always” discharge the amount of fuel corresponding to the instruction from the control unit (in other words, the control unit can instruct the pump to discharge the fuel without any limitation). It is premised on that). However, in general, a fuel discharge pump has a maximum discharge amount that can be indicated (upper limit amount due to a pump structure, a pump control mechanism, and the like). Therefore, when the discharge amount (the above “total”) that the control unit should instruct the pump becomes larger than the maximum discharge amount, the control unit cannot make the actual discharge amount coincide with the discharge amount, and the first abnormality determination May not be performed properly.

  Therefore, the first abnormality determination of the present invention is performed only when “the condition that the indicated discharge amount is equal to or greater than the threshold discharge amount when the instruction to the reduction valve is closed” is not satisfied. It has come to be. The reason for this is as follows. First, as described above, regardless of whether the reduction valve is normal or abnormal, the discharge amount is added to the discharge amount when the instruction to the reduction valve changes from “closed” to “open”. (Discharge amount is increased). Therefore, from the viewpoint of appropriately determining the first abnormality, the discharge amount “before” when the discharge amount is increased (when the instruction to the reduction valve is “closed”) is the maximum discharge amount that can be instructed to the pump. It needs to be small enough. Therefore, the first abnormality determination is performed when “the condition that the instructed discharge amount is equal to or greater than the threshold discharge amount when the instruction to the reduction valve is closed” is “not satisfied”. The threshold discharge amount is an amount sufficiently smaller than the maximum discharge amount that can be instructed to the pump, and a specific example thereof will be described later.

-2nd abnormality determination On the other hand, the 2nd abnormality determination of this invention is performed when "the said condition is satisfied". In the second abnormality determination, unlike the first abnormality determination, it is determined whether or not the weight reduction valve is abnormal based on the transition of the “fuel pressure”.

  In terms of fuel pressure, when the reduction valve is “normal”, the instruction to the reduction valve changes from closing to opening and even if the discharge amount is added to the discharge amount, the reduction valve opens and the added amount is reduced. Since it is offset, the fuel pressure does not change. In other words, in this case, if the instruction to the reduction valve is changed from closed to open without adding the discharge amount to the discharge amount (in other words, while maintaining the correction amount at zero), the amount of discharge is reduced. As the fuel supplied to the injection valve is insufficient, the fuel pressure decreases (see also FIG. 4).

  On the other hand, if an “open sticking abnormality” or “closed sticking abnormality” has occurred in the reduction valve, an instruction is given to the reduction valve without adding the discharge amount to the discharge amount (while maintaining the correction amount at zero). Even if the valve is changed from closed to open, the actual open / close state of the reduction valve does not change (it remains open or closed), so the fuel pressure does not change (see also FIG. 4).

  In this way, when the “open sticking abnormality” or “close sticking abnormality” occurs in the reduction valve, “change the instruction to the reduction valve from closed to open while maintaining the correction amount to zero”. However, the fuel pressure is maintained (not changed) at the value before the instruction is changed. Further, as can be understood from the above description, the change in the fuel pressure is caused by the abnormality of the weight reducing valve. Therefore, based on the transition of the fuel pressure described above, the abnormality determination of the reduction valve can be performed separately from the abnormality determination of other members. This is the “second abnormality determination” in the present invention.

  Note that the second abnormality determination causes a variation different from the variation that normally occurs in the fuel system with respect to the fuel pressure (which causes a forced decrease in the fuel pressure when the weight reduction valve is normal). Therefore, from the viewpoint of fuel pressure control, it is preferable to execute the first abnormality determination rather than the second abnormality determination. However, in general, the fuel system is designed such that the maximum discharge amount that can be instructed to the pump is sufficiently large with respect to the assumed discharge amount. Therefore, in principle, the above-described condition for performing the second abnormality determination (the discharge amount instructed when the instruction to the reduction valve is closed is not less than the threshold discharge amount) does not hold. However, as an exception, the above condition is satisfied when a feedback amount (for example, an integral term in PID control) is excessively large due to manufacturing variations and aging deterioration of various members constituting the fuel system. there is a possibility. The second abnormality determination is an abnormality determination method for dealing with such an exceptional situation.

  As described above, the abnormality determination device of the present invention has an abnormality in the reduction valve while selecting an abnormality determination method (first abnormality determination / second abnormality determination) corresponding to the discharge amount instructed to the pump. Whether or not can be determined independently.

  By the way, “abnormal” of the weight reduction valve means that an open sticking abnormality or a closed sticking abnormality has occurred in the weight reduction valve. On the contrary, that the weight reduction valve is not abnormal (normal) indicates that neither the open sticking abnormality nor the closed sticking abnormality has occurred in the weight reducing valve.

  Furthermore, the “feedback amount” for controlling the fuel pressure is not particularly limited as long as it is a control amount based on the deviation of the actual value from the target value of the fuel pressure. For example, the feedback amount may be calculated so as to include one or both of a proportional term (P term) based on the deviation and an integral term (I term) based on the time integral value of the deviation. Further, a differential term (D term) based on the time differential value of the same deviation may be added to the feedback amount thus calculated.

  Furthermore, the “discharge amount” instructed to the pump, the “maximum discharge amount” that can be instructed, and the “threshold discharge amount” may be parameters corresponding to the pump control mechanism in the fuel system, and are not particularly limited. For example, the volume of fuel discharged from the pump per unit time, the duty ratio of the input voltage to the pump when the pump is controlled by a PWM (Pulse Width Modulation) method, and the like can be adopted as the discharge amount. . Similarly, for example, the maximum volume of fuel that can be discharged from the pump per unit time, the maximum value (= 1) of the duty ratio of the input voltage in PWM control, and the like can be adopted as the maximum discharge amount. Furthermore, for example, an amount obtained by subtracting a predetermined amount from the maximum discharge amount can be adopted as the threshold discharge amount (details will be described later).

  The abnormality determination device of the present invention has been described above. Next, several modes (modes 1 to 3) of the abnormality determination device of the present invention will be described below.

・ Mode 1
The “threshold discharge amount” may be set to an amount that does not reach the maximum discharge amount of the pump even if the discharge amount is added to the discharge amount. Specifically, the threshold discharge amount is set so that the difference between the maximum discharge amount of the pump and the threshold discharge amount is larger than the discharge amount (that is, the threshold discharge amount is less than the amount obtained by subtracting the discharge amount from the maximum discharge amount). Should be determined so that there is less. On the other hand, the frequency with which the second abnormality determination is performed increases as the threshold discharge amount is set to a smaller amount. However, as described above, from the viewpoint of fuel pressure control, it is preferable that the frequency of the second abnormality determination be as low as possible (that is, the threshold discharge amount is large).

Therefore, as one aspect,
The threshold discharge amount may be set to an amount smaller by the discharge amount than the maximum discharge amount that can be instructed to the pump.

  With the above configuration, it is possible to determine the abnormality of the reduction valve while minimizing the influence of the second abnormality determination on the fuel pressure control as much as possible.

・ Aspect 2
Similar to the above-described conventional fuel system, the “control unit” may be configured to instruct the reduction valve to open when the discharge amount instructed to the pump becomes a predetermined lower limit amount or less. For example, the control unit instructs the reduction valve to open when the required amount in the injection valve is less than or equal to the lower limit amount, and instructs the reduction valve to close when the required amount is greater than the lower limit amount. It can be configured (see also FIG. 2). That is, the control unit can be configured to give an instruction to open and close the reduction valve (for the purpose of proper operation of the pump) for a reason different from the abnormality determination of the reduction valve. Further, the control unit may give an opening / closing instruction to the reduction valve for the purpose of determining abnormality of the reduction valve instead of such an opening / closing instruction.

  In other words, in the above “first abnormality determination”, each feedback amount when the instruction to the reduction valve is open or closed is positively instructed to open / close the reduction valve for the purpose of determining abnormality of the reduction valve. It may be acquired while giving (i.e., active), or may be acquired after waiting for a change in the opening / closing instruction of the reduction valve to change properly (i.e., passively) for the purpose of proper operation of the pump.

For example, as the former (open / close instruction for the purpose of abnormality determination), the control unit
In the first abnormality determination, the absolute value of the amount of change in the feedback amount when the instruction to the reduction valve is changed from valve closing to valve opening, and the instruction to the reduction valve is changed from valve opening to valve closing. When at least one of the absolute values of the amount of change in the feedback amount is equal to or greater than a first threshold value, the reduction valve may be determined to be abnormal.

  The “first threshold value” may be an appropriate value that can determine that the weight reduction valve is abnormal when the absolute value of the change amount is equal to or greater than the first threshold value. It may be a value less than the amount. For example, the discharge amount itself or an amount smaller than the discharge amount by a predetermined amount can be adopted as the first threshold value.

・ Aspect 3
The “second abnormality determination” focuses on the fact that the fuel pressure “does not change” when the instruction to the reduction valve is changed while maintaining the correction amount at zero when the reduction valve is abnormal. However, even if the reduction valve is abnormal, the fuel pressure may change somewhat due to a feedback amount that changes every moment. Therefore, from the viewpoint of determining the abnormality of the reduction valve with higher accuracy, the second abnormality determination is performed when the amount of change in the fuel pressure does not reach “an amount that can be determined that the reduction valve is normal”. It may be configured to determine that

Specifically, as one aspect, the control unit
In the second abnormality determination, when the absolute value of the change amount of the fuel pressure when the instruction to the reduction valve is changed from the closed valve to the opened valve, it is determined that the reduction valve is abnormal. Can be configured.

  The “second threshold value” may be an appropriate value that can determine that the reduction valve is normal when the absolute value of the change amount of the fuel pressure is equal to or greater than the second threshold value. From the viewpoint of fuel pressure control, after it is determined in the second abnormality determination whether or not the reduction valve is abnormal, the instruction to the reduction valve is quickly returned (that is, the instruction is closed from the valve opening to the valve closing). Is preferable.

1 is a schematic diagram of an abnormality determination device according to an embodiment of the present invention, a fuel system to which the device is applied, and an internal combustion engine equipped with the system. FIG. 2 is an operation diagram of a fuel pump included in the fuel system described in FIG. 1. It is a time chart showing an example of the relationship between the state (normal or abnormal) of a reduction valve, and the various parameters in a fuel system. It is a time chart showing an example of the relationship between the state (normal or abnormal) of a reduction valve, and the various parameters in a fuel system. It is the flowchart which showed the routine which CPU of the abnormality determination apparatus which concerns on embodiment of this invention performs. It is the flowchart which showed the routine which CPU of the abnormality determination apparatus which concerns on embodiment of this invention performs. It is the flowchart which showed the routine which CPU of the abnormality determination apparatus which concerns on embodiment of this invention performs. It is the flowchart which showed the routine which CPU of the abnormality determination apparatus which concerns on embodiment of this invention performs.

<Embodiment>
[Outline of device]
With reference to FIG. 1, a schematic configuration of an abnormality determination device (hereinafter referred to as “implementation device”) according to an embodiment of the present invention will be described.

  FIG. 1 shows a schematic configuration of an internal combustion engine EG (hereinafter referred to as “engine EG”) equipped with a fuel system to which the implementation apparatus is applied. The engine EG is an in-cylinder injection / spark ignition type / four-cycle internal combustion engine. The engine EG has the following configurations (1) to (9).

(1) Fuel system A fuel injection valve 11, a delivery pipe 12, a fuel pump 13, a fuel tank 14, a weight reduction valve 15, and a fuel pressure sensor 16 are included in the fuel system.
(2) Cylinder block portion The cylinder 21, piston 22, connecting rod 23, crankshaft 24, and combustion chamber 25 are included in the cylinder block portion.
(3) Cylinder head portion The intake port 31, intake valve 32, intake cam shaft 33, exhaust port 34, exhaust valve 35, exhaust cam shaft 36, spark plug 37, and igniter 38 are included in the cylinder head portion.
(4) Intake system The intake manifold 41, the intake pipe 42, the air cleaner 43, the throttle valve 44, and the throttle valve actuator 44a are included in the intake system.
(5) Exhaust system The exhaust manifold 51, the exhaust pipe 52, and the exhaust gas purification catalyst 53 are included in the exhaust system.
(6) Accelerator pedal 61
(7) Ignition key switch 62
(8) Various sensors The crank position sensor 71, the air flow meter 72, the air-fuel ratio sensors 73 and 74, the intake air temperature sensor 75, and the water temperature sensor 76 are included in the various sensors.
(9) Electronic control device 81

  The reduction valve 15 included in the fuel system can switch between supplying all of the fuel discharged from the fuel pump 13 to the fuel injection valve 11 and supplying a part of the fuel to the fuel injection valve 11. This is an open / close valve. Specifically, the reduction valve 15 is provided on a fuel supply path that connects the fuel pump 13 and the fuel injection valve 11 (strictly, the delivery pipe 12), and an instruction signal (open valve) of the electronic control device 81 is provided. It opens and closes based on an instruction or a valve closing instruction). When the valve 15 is opened, a part of the fuel discharged from the fuel pump 13 is discharged from the fuel supply path and returned to the fuel tank 14. That is, at this time, “a part” of the fuel discharged from the fuel pump 13 (fuel other than the fuel returned to the fuel tank 14) is supplied to the fuel injection valve 11. On the other hand, when the valve 15 is closed, the discharge is not performed. That is, at this time, “all” of the fuel discharged from the fuel pump 13 is supplied to the fuel injection valve 11.

The fuel pump 13 is configured to increase the pressure of the fuel supplied from the fuel tank 14 and to discharge an amount of fuel corresponding to an instruction signal from the electronic control device 81. Specifically, the electronic control unit 81 calculates the total amount of the following (A), (B), and (C) as the discharge amount Fout of the fuel pump 13 and discharges the fuel with the discharge amount Fout. An instruction is given to the pump 13 (see also the fuel pressure control routine of FIG. 5). Hereinafter, the discharge amount Fout instructed to the fuel pump 13 is also simply referred to as “discharge amount Fout”.
(A) Required amount Finj required in the fuel injection valve 11
(B) Feedback amount Ffb in feedback control for controlling fuel pressure
(C) When the instruction to the reduction valve 15 is open, the discharge amount Fd discharged through the reduction valve 15 is set, and when the instruction to the reduction valve 15 is closed, it is set to zero. Correction amount Fvopen

  The fuel pump 13 is controlled by the PWM method. Specifically, after determining the discharge amount Fout as described above, the electronic control unit 81 determines the duty ratio of the input voltage to the fuel pump 13 so as to correspond to the discharge amount Fout, and sets the duty ratio to the fuel. An instruction signal is transmitted to a controller (so-called FPC, Fuel Pump Controller, not shown) that operates the pump 13. That is, the discharge amount Fout in this example substantially represents the duty ratio.

  FIG. 2 is an operation diagram of the fuel pump 13 (relationship between the required amount Finj, the feedback amount Ffb, the correction amount Fvopen (zero or the discharge amount Fd), and the discharge amount Fout). Based on the value of the horizontal axis (Finj + Ffb), the electronic control unit 81 gives an instruction to the fuel pump 13 to discharge the fuel having the value of the vertical axis (Fout). As shown on the vertical axis (Fout) in FIG. 2, the fuel pump 13 has a maximum amount (maximum discharge amount) Fmax of the discharge amount Fout that can be instructed by the electronic control device 81 due to its structure, control mechanism, and the like. . In the PWM control, instructing the maximum discharge amount Fmax is to set the duty ratio of the input voltage to the fuel pump 13 to “1” (that is, substantially no PWM control is performed). Equivalent to.

  Further, as indicated by the vertical axis (Fout), the fuel pump 13 is not used in a region where the discharge amount Fout is smaller than a predetermined minimum amount (minimum discharge amount) Fmin. Specifically, the amount of the horizontal axis (Finj + Ffb) is compared with the minimum discharge amount Fmin, and the amount of discharge Fd is added to the amount of the horizontal axis (when the amount of the horizontal axis (Finj + Ffb) is less than the minimum discharge amount Fmin). The amount obtained is used as the discharge amount Fout. For example, when the amount on the horizontal axis is Fmin, the discharge amount is Fmin + Fd, and when the amount on the horizontal axis is zero, the discharge amount is Fmin.

  However, when the discharge amount Fd is added in this way, the reduction valve 15 is instructed to “open”. Therefore, if the reduction valve 15 is normal, an amount of fuel (= Finj + Ffb) obtained by subtracting the discharge amount Fd from the discharge amount Fout (= Finj + Ffb + Fd) is supplied to the fuel injection valve 11. Therefore, in this case, even if the discharge amount Fd is added to the discharge amount Fout, the amount of fuel that is finally supplied to the fuel injection valve 11 remains the horizontal axis amount Finj + Ffb. On the other hand, when the amount Finj + Ffb on the horizontal axis is larger than the minimum discharge amount Fmin, the valve 15 is instructed to “close”. Therefore, if the reduction valve 15 is normal, the fuel of the discharge amount Fout (= Finj + Ffb) is supplied to the fuel injection valve 11 as it is. Therefore, also in this case, the fuel of the discharge amount Fout (= Finj + Ffb) is supplied to the fuel injection valve 11. Thus, if the reduction valve is normal, the fuel of the horizontal axis amount Finj + Ffb is supplied to the fuel injection valve 11 regardless of the horizontal axis amount Finj + Ffb (regardless of the opening / closing instruction to the reduction valve 15).

  The minimum discharge amount Fmin is a minimum discharge amount that can maintain a proportional relationship (linearity) between the discharge amount instructed to the fuel pump 13 and the actual discharge amount, and is determined in advance by an experiment or the like. ing. In this example, the fuel system is designed so that the minimum discharge amount Fmin and the discharge amount Fd coincide.

  Further, as shown on the vertical axis (Fout), an amount smaller than the instructable maximum discharge amount Fmax by the discharge amount Fd is shown as a threshold discharge amount Foutth. The threshold discharge amount Foutth is an amount used in abnormality determination described later. Details of the threshold discharge amount Foutth will be described later.

  In the above description, the minimum discharge amount Fmin and the parameter Finj + Ffb (corresponding to the horizontal axis in FIG. 2) are compared, and the instruction to the reduction valve 15 (instruction to open or close the valve) is switched. However, Finj (only the required amount) may be used instead of Finj + Ffb (the sum of the requested amount and the feedback amount) as a parameter to be compared with the minimum discharge amount Fmin for opening and closing the reducing valve 15. When only the required amount Finj is used, since the opening / closing process of the reducing valve 15 can be executed without considering the feedback amount Ffb, the control of the fuel system can be simplified.

  However, in the above case, depending on the magnitude of the feedback amount Ffb, the request amount Finj and the sum Finj + Ffb of the request amount and the feedback amount are greatly different, and it is considered that the reduction valve 15 cannot be opened and closed at an appropriate timing. . However, the feedback amount Ffb usually tends to gradually increase (for example, the integral term in PID control increases) due to deterioration of the fuel system over time. For this reason, there is a case where the valve opening instruction is given even though it is not necessary to open the reducing valve 15 (when Finj + Ffb> Fmin, but Finj <Fmin), the opposite case ( Normally, this is not the case when the valve closing instruction is given when the reduction valve 15 needs to be opened. Therefore, even if only the required amount Finj is used as the parameter, the fuel pump 13 is not normally used in a region where the discharge amount Fout is smaller than the minimum discharge amount Fmin. That is, there is no contradiction in the operation diagram of FIG.

  Referring to FIG. 1 again, the fuel discharged from the fuel pump 13 in accordance with the operation diagram described above is injected into the delivery pipe 12 through the fuel supply path. The fuel injection valve 11 injects fuel into the cylinder 21 in accordance with an instruction from the electronic control unit 81. The pressure (fuel pressure) of the fuel injected into the delivery pipe 12 is measured by the fuel pressure sensor 16.

  The electronic control device 81 is an electronic circuit mainly composed of a known microcomputer including a CPU, a ROM, a RAM, and the like. A CPU (hereinafter simply referred to as “CPU”) of the electric control device transmits instruction signals to the fuel injection valve 11, the fuel pump 13, the reduction valve 15, and the like, and receives signals output from the respective sensors. It is configured.

  The above is the outline of the fuel system to which the implementation apparatus is applied and the engine EG equipped with the fuel system.

[Determining abnormality of weight reduction valve]
With reference to FIG. 3 and FIG. 4, a method for determining the abnormality of the weight reduction valve 15 in the implementation apparatus will be described in the order of “first abnormality determination” and “second abnormality determination”. 3 and 4 are time charts showing an example of the relationship between the state of the weight reducing valve 15 (normal, open stuck abnormality, closed stuck abnormality) and various parameters in the fuel system. 3 and 4, “solid line” represents the transition of the same parameter when the weight reducing valve 15 is normal, and “broken line” represents the transition of the same parameter when the sticking abnormality is occurring in the weight reducing valve 15. , “Dash-dotted line” represents the transition of the same parameter when a closed sticking abnormality occurs in the weight reducing valve 15.

  However, for convenience of explanation, in the time charts of FIGS. 3 and 4, the required amount Finj is maintained at a constant value A, and the reduction valve 15 is instructed to open and close. That is, in these time charts, the reduction valve 15 is instructed to open and close regardless of the magnitude of the requested amount Finj (that is, for the purpose of determining abnormality of the reduction valve 15).

・ First abnormality determination (Fig. 3)
In the example shown in FIG. 3, “opening” is instructed to the reducing valve 15 at time t0, and “closing” is instructed to the reducing valve 15 at time t1 when a predetermined time has elapsed from time t0. . At this time, if the reduction valve 15 is “normal”, the open / close state of the reduction valve 15 changes from open to closed at time t1. However, when the “open sticking abnormality” has occurred, the open / close state of the reduction valve 15 does not change, and the reduction valve 15 remains open. Similarly, when the “closed sticking abnormality” has occurred, the reduction valve 15 remains closed.

  Further, at time t1, the correction amount Fvopen decreases from the discharge amount Fd to zero together with the instruction to close the valve. When the reduction valve 15 is “normal”, the reduction valve 15 is closed as the correction amount Fvopen decreases, so that the fuel pressure FP is maintained at the target pressure FPtgt before and after time t1. However, when the “open sticking abnormality” has occurred, the correction amount Fvopen decreases while the reduction valve 15 remains open (that is, the open / close state of the reduction valve 15 remains unchanged), so the fuel injection valve 11 And the fuel pressure FP decreases so as to deviate from the target pressure FPtgt. Similarly, when the “closed sticking abnormality” has occurred, the correction amount Fvopen is reduced to zero while the open / close state of the reduction valve 15 remains unchanged, so the fuel pressure FP decreases. The fuel shortage described above is equal to the discharge amount Fd.

  Therefore, when the reduction valve 15 is “normal”, the feedback amount Ffb is maintained at the value B before and after time t1. However, when the “open sticking abnormality” or the “close sticking abnormality” has occurred, in order to make the decreased fuel pressure FP coincide with the target pressure FPtgt again (in other words, to compensate for the shortage of fuel (= Fd)). The feedback amount Ffb increases. The increase amount in this case is Fd. As a result, the fuel pressure FP returns to the target pressure FPtgt. However, since a certain amount of response time is required for feedback control, the fuel pressure FP coincides with the target pressure FPtgt after a predetermined time has elapsed from time t1.

  Since the required amount Finj, the feedback amount Ffb, and the correction amount Fvopen change as described above, the discharge amount Fout instructed at the time t1 decreases when the reduction valve 15 is “normal”. The amount of decrease at this time is equal to the discharge amount Fd. On the other hand, when “open sticking abnormality” or “closed sticking abnormality” occurs, the discharge amount Fout once decreases and then returns to the original amount.

  At time t2 when a predetermined time has elapsed from time t1, the feedback amount Ffb has already converged, so the fuel pressure FP and the discharge amount Fout are stable. At time t2, the feedback amount when the “open sticking abnormality” has occurred is a value larger than the normal feedback amount B by the discharge amount Fd. On the other hand, the feedback amount when the “closed sticking abnormality” has occurred is substantially the same as the feedback amount B at the normal time.

  For the same reason as described above (reasons for changing each parameter), the feedback amount when the “open sticking abnormality” has occurred at time t0 when the valve opening is instructed to the reducing valve 15 is the feedback amount at the normal time. B is substantially the same as B, and the feedback amount when the “closed sticking abnormality” occurs is a value smaller than the normal feedback amount B by the discharge amount Fd.

  When a predetermined time elapses from time t2, “opening” is instructed to the reducing valve 15 at time t3. At this time, the transition of each parameter is the same as the transition when the “valve closing” is instructed to the reduction valve 15 at time t1 except that the sign is opposite. That is, the parameter increased at time t1 decreases at time t3, and the parameter decreased at time t1 increases at time t3. Therefore, when the reduction valve 15 is “normal” at time t3, the feedback amount Ffb is maintained at the value B before and after time t3. However, when “open sticking abnormality” or “close sticking abnormality” occurs, the feedback amount Ffb decreases by an amount corresponding to the discharge amount Fd.

  As described above, when the “open sticking abnormality” or the “close sticking abnormality” occurs in the reduction valve 15, the feedback amount Ffb changes when the instruction to the reduction valve 15 changes. In other words, the feedback amount during the period when the instruction to the reduction valve 15 is opened is different from the feedback amount during the period when the instruction is closed. Therefore, based on the difference between the former feedback amount and the latter feedback amount, it can be determined whether or not the reduction valve 15 is abnormal. This determination method is referred to as “first abnormality determination”.

  However, as shown in FIG. 3, regardless of whether the reduction valve 15 is normal or abnormal, the discharge amount Fout increases when the instruction to the reduction valve changes from closing to opening at time t3. . Specifically, when the reduction valve 15 is “normal”, the discharge amount Fout increases by the discharge amount Fd, and even when the reduction valve 15 is “abnormal” (temporary feedback control). The discharge amount Fout increases until the response time elapses. Here, when the discharge amount Fout calculated at the time of increase is larger than the maximum discharge amount Fmax (for example, when the duty ratio exceeds 1), the actual discharge amount cannot be matched with the discharge amount Fout. In this case, the fluctuation of the feedback amount Ffb becomes small, and the accuracy of the first abnormality determination may be reduced. Therefore, from the viewpoint of accurately performing the first abnormality determination, it is desirable that the increased discharge amount Fout is smaller than the maximum discharge amount Fmax. Accordingly, the first abnormality determination is performed when the condition that “the discharge amount Fout when the instruction to the reduction valve 15 is closed is equal to or greater than the threshold discharge amount Foutth” is not satisfied. Note that the threshold discharge amount Foutth in this example is an amount smaller by the discharge amount Fd than the maximum discharge amount Fmax, as shown in FIG.

・ Second abnormality determination (Fig. 4)
On the other hand, when the above condition (the discharge amount Fout when the instruction to the reduction valve 15 is closed is equal to or greater than the threshold discharge amount Foutth) is satisfied, the discharge amount Fout is set to the maximum discharge amount by performing the second abnormality determination. Abnormality determination can be performed while preventing reaching Fmax.

  In the example shown in FIG. 4, the valve closing is instructed to the reducing valve 15 at time t0, and the valve opening is instructed to the reducing valve 15 at time t1 when a predetermined time has elapsed from time t0. . However, unlike the example shown in FIG. 3, the correction amount Fvopen is maintained at zero even when the reduction valve 15 is instructed to open at time t <b> 1.

  If the reduction valve 15 is “normal”, although the reduction valve 15 is opened, the correction amount Fvopen remains zero, so the fuel pressure FP decreases at time t1. However, when “open sticking abnormality” or “close sticking abnormality” has occurred, the open / close state of the reducing valve 15 does not change, so the fuel pressure FP is maintained at the target pressure FPtgt.

  As described above, when the “open sticking abnormality” or the “close sticking abnormality” occurs in the reduction valve 15, the instruction to the reduction valve 15 changes from the closed valve to the opened valve while the correction amount Fvopen is maintained at zero. The fuel pressure FP does not change. That is, the transition of the fuel pressure FP when the reduction valve 15 is normal differs from the transition of the fuel pressure FP when the reduction valve 15 is abnormal. Therefore, based on the transition of the fuel pressure FP, it can be determined whether or not the reduction valve 15 is abnormal. This determination method is referred to as “second abnormality determination”.

  In the second abnormality determination, from the viewpoint of fuel pressure control, after the abnormality determination of the reduction valve 15 is completed, the instruction to the reduction valve 15 is promptly restored without waiting for correction of the fuel pressure FP by feedback control (that is, The instruction is preferably changed from valve opening to valve closing at time t2. As a result, as shown in FIG. 4, the feedback amount Ffb when the reduction valve 15 is normal starts to increase after the time t1, but the reduction valve 15 closes at the time t2, so the original amount is promptly restored. Return to quantity C. As a result, the discharge amount Fout similarly increases slightly after time t1 and then returns to the original amount A + C. As a result, even when “the discharge amount Fout when the instruction to the reduction valve 15 is closed is equal to or greater than the threshold discharge amount Foutth”, the discharge amount Fout is prevented from increasing and the discharge amount Fout is the maximum discharge amount. Reaching Fmax can be prevented. Therefore, the abnormality determination of the weight reduction valve 15 can be appropriately executed.

[Operation of the device]
The actual operation of the implementation apparatus will be described with reference to FIGS. In the implementation apparatus, the CPU executes a “fuel pressure control” routine shown in FIG. 5 and controls the fuel pressure FP by adjusting the discharge amount Fout instructed to the fuel pump 13. Further, the CPU executes a “determining abnormality of the weight reduction valve” routine shown in FIGS. 6 to 8 to determine whether or not the weight reduction valve 15 is abnormal (whether an open sticking abnormality or a closed sticking abnormality has occurred). judge.

  Note that times t0, t1, t2, and t3 in the following description correspond to times t0, t1, t2, and t3 in FIGS. 3 and 4, respectively.

  First, the CPU executes the routine of FIG. 5 every time a predetermined time elapses. When the processing of this routine is started, the CPU proceeds from step 500 to step 505 to determine the current request amount Finj (t). For example, when the current time is t0, the requested amount Finj (t0) is determined based on another routine (not shown) for determining the requested amount based on the operating state of the engine EG and the like. ing.

  Next, the CPU proceeds to step 510 to determine whether or not an abnormality determination (first abnormality determination or second abnormality determination) of the weight reduction valve 15 is currently being executed. Specifically, the CPU determines that the abnormality determination is not currently performed (that is, “Yes”) unless the routine of FIG. 7 or FIG. On the other hand, if the CPU is executing the routine, the CPU determines that the abnormality determination is currently being performed (that is, “No”).

  When abnormality determination is not executed at the present time, the CPU determines “Yes” and proceeds to step 515. In step 515, the CPU determines “whether the requested amount Finj (t 0) is equal to or less than the minimum discharge amount Fmin” in order to determine an instruction to the reduction valve 15. That is, in this example, Finj (only the required amount) is used as a parameter to be compared with the minimum discharge amount Fmin for opening / closing the reduction valve 15. The minimum discharge amount Fmin is determined in advance by an experiment or the like and stored in the ROM.

  For example, if the requested amount Finj (t0) at the current time (time t0) is equal to or less than the minimum discharge amount Fmin, the CPU determines “Yes” in step 515 and proceeds to step 520. In step 520, the CPU stores the discharge amount Fd in the value of the correction amount Fvopen. The discharge amount Fd is determined in advance by an experiment or the like and stored in the ROM. Although the discharge amount Fd in this example is a fixed value, a variable value that takes into account the deterioration over time of the reduction valve 15 or the like may be used as the discharge amount Fd. Next, the CPU proceeds to step 525 and transmits an instruction to open the reduction valve 15 to an actuator (not shown) that opens and closes the reduction valve 15.

  On the other hand, if the requested amount Finj (t0) at the current time (time t0) is larger than the minimum discharge amount Fmin, the CPU makes a “No” determination at step 515 to proceed to step 530. In step 530, the CPU stores zero in the value of the correction amount Fvopen. Next, the CPU proceeds to step 535 and transmits an instruction to close the reduction valve 15 to an actuator (not shown) that opens and closes the reduction valve 15.

  Thus, when the requested amount Finj (t0) at the present time (time t0) is equal to or less than the minimum discharge amount Fmin, the valve opening is instructed to the reduction valve 15, and the value of the correction amount Fvopen is set to the discharge amount Fd. The On the other hand, when the requested amount Finj (t0) is larger than the minimum discharge amount Fmin, the valve closing is instructed to the reducing valve 15 and the value of the correction amount Fvopen is set to zero.

  After each process described above, the CPU proceeds to step 540 to determine the current fuel pressure control feedback amount Ffb (t0). The feedback amount Ffb (t0) is determined based on another routine (not shown) that performs proportional / integral control (PI control) for making the current fuel pressure FP (t0) coincide with the target pressure FPtgt (t0). It is like that.

  Specifically, the CPU acquires the fuel pressure FP (t0) based on the output value of the fuel pressure sensor 16, and calculates a deviation ΔFP (t0) between the target pressure FPtgt (t0) and the fuel pressure FP (t0). Furthermore, the CPU calculates a proportional term FBp (t0) of the feedback amount by multiplying the deviation ΔFP (t0) by a predetermined gain Kp. The target pressure FPtgt (t0) is determined based on a map (not shown) for determining the target pressure FPtgt based on the operating state of the engine EG. The gain Kp is an appropriate value determined in advance by an experiment or the like, and is stored in the ROM.

  Next, the CPU multiplies the deviation ΔFP (t) by time integration (integration value from the integration start time point τ = 0 to the current time point τ = t) by a predetermined gain Ki, whereby the feedback amount integral term FBi ( t0) is calculated. The integration start time (τ = 0 time) is the first start of the fuel system. The gain Ki is an appropriate value determined in advance by an experiment or the like, and is stored in the ROM.

  Then, the CPU calculates a feedback amount Ffb (t0) by multiplying the sum of the proportional term FBp (t0) and the integral term FBi (t0) by a predetermined coefficient Kfb. The coefficient Kfb is a coefficient for converting the proportional term FBp (t0) and the integral term FBi (t0) calculated as the “fuel pressure” values into “discharge amount” instructing the fuel pump 13. The coefficient Kfb is predetermined by a prior experiment or the like and stored in the ROM.

  After the processing in step 540, the CPU proceeds to step 545 to calculate the discharge amount Fout (t0) according to the following equation (1). As shown in the following equation (1), the discharge amount Fout (t) is the total amount of the requested amount Finj (t), the feedback amount Ffb (t), and the correction amount Fvopen.

  Fout (t) = Finj (t) + Ffb (t) + Fvopen (1)

  Next, the CPU proceeds to step 550 and gives an instruction to the fuel pump 13 to discharge the fuel of the discharge amount Fout (t0). Specifically, the CPU specifies the “duty ratio of the input voltage of the fuel pump 13 corresponding to the discharge amount Fout (t0)” with reference to a map or the like stored in the ROM, and this duty ratio is determined. Is transmitted as an instruction signal to a controller (FPC) for operating the.

  Thereafter, the CPU proceeds to step 595 to end the present routine tentatively.

  On the other hand, if the abnormality determination is being executed at the current time in step 510, the CPU determines “No” and proceeds directly to step 540. Therefore, in this case, switching of opening / closing of the reducing valve 15 based on the comparison between the requested amount Finj and the minimum discharge amount Fmin (step 525 or step 535) is not performed. Instead of this switching, in this case, switching of opening / closing of the reduction valve 15 is performed according to each abnormality determination method (details will be described later). Therefore, in this case, the value of the correction amount Fvopen is set to a value according to each abnormality determination method.

  Thereafter, similarly to the above, the CPU executes the processing of step 540 to step 550 and gives an instruction to the fuel pump 13 to discharge the fuel of the discharge amount Fout (t0). Thereafter, the CPU proceeds to step 595 to end the present routine tentatively.

  Further, the CPU executes a “determination of abnormality of the reduction valve” routine shown in FIG. 6 every time a predetermined time elapses. When the processing of this routine is started, the CPU proceeds from step 600 to step 610, and determines whether or not the “determination execution condition” for determining abnormality of the reduction valve 15 is satisfied at the present time (time t0). . Specifically, the CPU determines that the determination execution condition is satisfied when all of the following conditions 1 to 3 are satisfied, and the determination execution condition is not satisfied when any one of the following conditions 1 to 3 is not satisfied. judge.

(Condition 1)
The predetermined time has passed since the previous abnormality determination. For example, the integrated value of the number of times the reduction valve 15 is opened and closed after the previous abnormality determination is completed is equal to or greater than a predetermined threshold value.
(Condition 2)
The engine EG is in steady operation. For example, the change rate of the rotational speed of the engine EG is less than a predetermined threshold, the change rate of the intake air amount of the engine EG is less than a predetermined threshold, and the change rate of the correction amount related to the air-fuel ratio control of the engine EG is a predetermined value. Be below threshold.
(Condition 3)
The fuel injection valve 11, the fuel pressure sensor 16, and the various sensors 71 to 74 are normal.

  Condition 1 is a condition for preventing the frequency at which abnormality determination is performed from becoming excessively high. Condition 2 is a condition for performing abnormality determination when fluctuations in the required amount Finj and the target pressure FPtgt resulting from the air-fuel ratio control of the engine EG are as small as possible. The rotational speed of the engine EG is calculated based on the output value of the crank position sensor 71, the intake air amount of the engine EG is calculated based on the output value of the air flow meter 72, and the correction amount relating to the air-fuel ratio control of the engine EG is It is calculated based on the output values of the air-fuel ratio sensors 73 and 74. Condition 3 is a condition for ensuring that the result of the abnormality determination is correct. The determination as to whether or not the fuel injection valve 11, the fuel pressure sensor 16, and the various sensors 71 to 74 are normal is performed based on another routine (not shown) that performs the determination according to a known method. Each threshold value in the conditions 1 to 3 is determined in advance by a prior experiment or the like and stored in the ROM.

  If the determination execution condition is not satisfied at this time, the CPU makes a “No” determination at step 610 to proceed to step 695 to end the present routine tentatively. That is, in this case, the abnormality determination of the reduction valve 15 is not performed.

  On the other hand, if the determination execution condition is satisfied at the present time, the CPU determines “Yes” in step 610 and proceeds to step 620. In step 620, the CPU determines whether or not the discharge amount Fout instructed when the instruction to the reduction valve 15 is closed is equal to or greater than the threshold discharge amount Foutth. Specifically, if the instruction to the reduction valve 15 at the present time (time t0) is closed, the CPU determines whether or not the current discharge amount Fout (t0) is equal to or greater than the threshold discharge amount Foutth. On the other hand, if the instruction to the reduction valve 15 at the present time is open, the CPU waits until the instruction to the reduction valve 15 is closed, and when the instruction to the reduction valve 15 is closed. It is determined whether or not the discharge amount Fout is equal to or greater than the threshold discharge amount Foutth. The threshold discharge amount Foutth is set as a value smaller by the discharge amount Fd than the instructable maximum discharge amount Fmax (see FIG. 2) and stored in the ROM.

  If the discharge amount Fout instructed when the instruction to the reduction valve 15 is closed is not equal to or greater than the threshold discharge amount Foutth, the CPU makes a “No” determination at step 620 to proceed to step 630. In step 630, the CPU executes the “first abnormality determination” routine shown in FIG. 7 to determine whether or not the weight reduction valve 15 is abnormal (details will be described later with reference to FIG. 7). .) On the other hand, if the discharge amount Fout when the instruction to the reduction valve 15 is closed is equal to or greater than the threshold discharge amount Foutth, the CPU makes a “Yes” determination at step 620 to proceed to step 640. In step 640, the CPU determines whether or not the weight reduction valve 15 is abnormal by executing the “second abnormality determination” routine shown in FIG. 8 (details will be described later with reference to FIG. 8). .)

  For example, when executing “first abnormality determination”, the CPU starts the process from step 700 in FIG. 7 and proceeds to step 710. The CPU acquires the feedback amount Ffb1 when the opening / closing instruction to the reduction valve 15 is in the current state (in this example, the valve opening instruction) by executing the processing of step 710 and step 720. The CPU stores the acquired feedback amount Ffb1 in the RAM.

  Specifically, the CPU sequentially applies the feedback amount Ffb (τ) to the following expression (2) in the period from the current time (time τ = t0) to the time (t = t0 + ta) when the annealing time ta elapses. An annealing value Ffb1 (τ) is calculated. In the following equation (2), the value N is the number of executions of the calculation by the following equation (initial value is 1), and the initial value of the smoothed value Ffb1 (τ) is zero.

Ffb1 (τ) = Ffb1 (τ−1) + (Ffb1 (τ) −Ffb1 (τ−1)) / N
... (2)

  The CPU proceeds to step 720 each time the processing of step 710 is performed, and determines whether or not the annealing time ta has elapsed from time t0 (that is, whether or not the current time is time t0 + ta). If the warming time ta has not yet elapsed at the present time, the CPU makes a “No” determination at step 720 to return to step 710 again and repeat the processing of the same step. During this time, the processing of step 510 and step 540 to step 550 in FIG. 5 is repeatedly executed.

  When the annealing time ta elapses, the CPU makes a “Yes” determination at step 720 to proceed to step 730. In step 730, the CPU changes the opening / closing instruction to the reduction valve 15. Specifically, if the instruction to the reduction valve 15 at the present time (time t0 + ta) is opened, the CPU instructs the reduction valve 15 to close. On the contrary, if the instruction to the reduction valve 15 at the present time is the valve closing, the CPU instructs the reduction valve 15 to open the valve. Further, along with this instruction, the CPU switches the correction amount Fvopen in accordance with the instruction to the reduction valve 15. Specifically, the correction amount Fvopen is set to the discharge amount Fd when the reduction valve 15 is instructed to open, and the correction amount Fvopen is set to zero when the reduction valve 15 is instructed to close (see FIG. See also 5.)

  In this example, the CPU executes the process of step 730 at a time point (time t1) after a predetermined time has elapsed from the time point determined as “Yes” in step 720 (time t0 + ta). The instruction to 15 is changed from valve opening to valve closing.

  Next, the CPU proceeds to step 740. As described above, the CPU executes the processing of step 740 and step 750 to obtain the feedback amount Ffb2 when the opening / closing instruction to the reduction valve 15 is in the current state (in this example, the valve closing instruction). The CPU stores the acquired feedback amount Ffb2 in the RAM.

  Specifically, the CPU performs feedback in a period from when the feedback amount is stabilized after changing the instruction to the reduction valve 15 (time τ = t2) to when the annealing time ta elapses (t = t2 + ta). The amount Ffb (τ) is sequentially applied to the following equation (3) to calculate the smoothed value Ffb2 (τ). In the following equation (3), the value N is the number of executions of the calculation by the following equation (initial value is 1), and the initial value of the smoothed value Ffb2 (τ) is zero.

Ffb2 (τ) = Ffb2 (τ−1) + (Ffb (τ) −Ffb2 (τ−1)) / N
... (3)

  The CPU proceeds to step 750 each time the process of step 740 is performed, and determines whether or not the annealing time ta has elapsed from time t2 (that is, whether or not the current time is time t2 + ta). If the warming time ta has not yet elapsed at the present time, the CPU makes a “No” determination at step 750 to return to step 740 again and repeat the processing of the same step. In the same manner as described above, the processing of step 510 and step 540 to step 550 in FIG.

  When the annealing time ta elapses, the CPU makes a “Yes” determination at step 750 to proceed to step 760. In step 760, the CPU determines that the absolute value | Ffb1-Ffb2 | of the difference between the feedback amount Ffb1 before changing the opening / closing instruction to the reduction valve 15 and the feedback amount Ffb2 after changing the instruction is predetermined. It is determined whether it is more than 1st threshold value Thr1. The first threshold Thr1 is a value by which it can be determined that the weight reducing valve 15 is abnormal when the absolute value is equal to or greater than the first threshold Thr1. The first threshold value Thr1 is determined in advance by a prior experiment or the like and stored in the ROM.

  If the absolute value is greater than or equal to the first threshold Thr1, the CPU makes a “Yes” determination at step 760 to proceed to step 770, where it determines that “an abnormality has occurred in the reducing valve 15”. On the other hand, when the absolute value is smaller than the first threshold value Thr1, the CPU makes a “No” determination at step 760 to proceed to step 780, and determines that “there is no abnormality in the reducing valve 15”. Thereafter, the CPU proceeds to step 795 to end the present routine tentatively.

  When the CPU ends the routine of FIG. 7, the CPU returns to step 630 of FIG. Then, the CPU proceeds to step 695 to end the present routine tentatively.

  On the other hand, when executing the “second abnormality determination”, the CPU starts the process from step 800 in FIG. 8 and proceeds to step 810. In step 810, the CPU stores the fuel pressure FP (t1) at the present time (for example, time t1 after a predetermined time has elapsed from time t0) in the RAM.

  Next, the CPU proceeds to step 820. In addition, the instruction | indication to the reduction valve 15 at this time is a valve closing, as it determined with "Yes" in step 620 of FIG. In step 820, the CPU instructs the reduction valve 15 to open while maintaining the correction amount Fvopen at zero. Then, the CPU proceeds to step 830. In step 830, the CPU acquires the fuel pressure FP (t1 + tb) after a predetermined time tb has elapsed from the time when the reduction valve 15 is instructed to open. The CPU stores the acquired fuel pressure FP (t1 + tb) in the RAM. The predetermined time tb is a time required for the fuel pressure FP to fall to such an extent that an abnormality can be determined. The predetermined time tb is predetermined by a prior experiment or the like and stored in the ROM.

  Next, the CPU proceeds to step 840. In step 840, the CPU determines that the absolute value of the difference between the fuel pressure FP (t1) before instructing the reduction valve 15 to open and the fuel pressure FP (t1 + tb) after instructing the reduction valve 15 to open is calculated. It is determined whether or not it is equal to or greater than a predetermined second threshold Thr2. The second threshold Thr2 is a value with which it can be determined that the weight reducing valve 15 is normal when the absolute value is equal to or greater than the second threshold Thr2. The second threshold Thr2 is determined in advance by a prior experiment or the like and stored in the ROM.

  If the absolute value is greater than or equal to the second threshold Thr2, the CPU makes a “Yes” determination at step 840 to proceed to step 850, where it determines that “there is no abnormality in the reduction valve 15”. Thereafter, the CPU proceeds to step 860 to instruct the reduction valve 15 to close at a time t2 when a predetermined time has elapsed from the time t1 + tb. Then, the CPU proceeds to step 895 to end the present routine tentatively.

  On the other hand, if the absolute value is not greater than or equal to the second threshold Thr2, the CPU makes a “No” determination at step 840 to proceed to step 870 to determine that “an abnormality has occurred in the reducing valve 15”. Thereafter, the CPU proceeds to step 860 to instruct the reduction valve 15 to close, and proceeds to step 895 to end the present routine tentatively.

  When the CPU completes the routine of FIG. 8, the CPU returns to step 640 of FIG. Then, the CPU proceeds to step 695 to end the present routine tentatively.

  As described above, the execution device performs the abnormality determination of the reduction valve 15 by an appropriate method (first abnormality determination and second abnormality determination) corresponding to the discharge amount Fout instructed to the fuel pump 13. Thereby, the implementation apparatus can determine whether the weight reduction valve 15 is abnormal, distinguishing it from the abnormality determination of another member.

<Other aspects>
The present invention is not limited to the above embodiment, and various modifications can be employed within the scope of the present invention.

  For example, the implementation apparatus uses proportional / integral control (PI control) as feedback control for controlling the fuel pressure (step 540 in FIG. 5). However, the abnormality determination device of the present invention may employ proportional / integral / derivative control (PID control) instead of proportional / integral control.

  Furthermore, the implementation apparatus determines that there is an abnormality in the weight reduction valve 15 when the determination condition for the first abnormality determination (step 760 in FIG. 7) is satisfied once. However, the abnormality determination device of the present invention may be configured to determine that there is an abnormality in the weight reduction valve 15 when the determination condition is satisfied a plurality of times. The same applies to the determination condition for the second abnormality determination (step 840 in FIG. 8).

  Furthermore, the abnormality determination device of the present invention may limit the number of times that abnormality determination is performed from the viewpoint of minimizing the influence of execution of abnormality determination on the engine EG. For example, the abnormality determination device of the present invention performs the second abnormality determination only once every time the engine EG performs an idle operation (an operation that stands by at a predetermined idle speed in a no-load state). You may restrict. Furthermore, the abnormality determination device according to the present invention performs the second abnormality determination every time a vehicle equipped with the engine EG travels once (that is, after a certain idle operation ends and the vehicle starts traveling) It may be limited to be executed only once (before the operation is started). The same applies to the first abnormality determination.

  Further, the execution device is applied to a fuel system in which the fuel injection valve 11 directly injects fuel into the cylinder 21 of the engine EG (that is, in-cylinder injection). However, the abnormality determination device of the present invention may be applied to a fuel system that injects fuel into the intake port 31 of the engine EG (that is, port injection). Furthermore, the abnormality determination device of the present invention may be applied to a fuel system that injects fuel into both the cylinder 21 and the intake port 31 of the engine EG (that is, a combination of in-cylinder injection and port injection).

DESCRIPTION OF SYMBOLS 11 ... Fuel injection valve, 13 ... Fuel pump, 15 ... Reduction valve, 16 ... Fuel pressure sensor, 81 ... Electronic control apparatus

Claims (4)

An injection valve that injects fuel, a pump that discharges fuel to a supply path connected to the injection valve, and a reduction valve that is provided on the supply path, and injects all of the fuel discharged by the pump when the valve is closed A weight reduction applied to a fuel system having a reduction valve that supplies a part of the discharged fuel to the injection valve by discharging a predetermined amount of fuel from the supply path when the valve is opened and opening the valve. An abnormality determination device for a valve,
A control unit that gives an instruction to open or close the reducing valve, instructs the pump to discharge, and determines whether or not the reducing valve is abnormal;
The controller is
The required amount of fuel in the injection valve, the feedback amount in feedback control for controlling the fuel pressure that is the pressure of the fuel supplied to the injection valve, and the discharge amount when the instruction to the reduction valve is open And instructing the discharge amount to the pump so as to discharge the sum of the correction amount set to zero when the instruction to the reduction valve is closed, and
As a first abnormality determination, when the condition that the instructed discharge amount is equal to or greater than a threshold discharge amount when the instruction to the reduction valve is closed, the instruction to the reduction valve is opened. Determining whether or not the reduction valve is abnormal based on the difference between the feedback amount during the period and the feedback amount during the period when the instruction to the reduction valve is closed,
As the second abnormality determination, when the condition is satisfied, the reduction amount is determined based on the change in the fuel pressure when the instruction to the reduction valve is changed from the valve closing to the valve opening while the correction amount is maintained at zero. Determine if the valve is abnormal,
Abnormality judgment device for weight reduction valve. In the abnormality determination device according to claim 1,
The threshold discharge amount is an amount smaller by the discharge amount than the maximum discharge amount that can be instructed to the pump.
Abnormality judgment device for weight reduction valve. In the abnormality determination device according to claim 1 or 2,
The control unit is
In the first abnormality determination, the absolute value of the amount of change in the feedback amount when the instruction to the reduction valve is changed from valve closing to valve opening, and the instruction to the reduction valve is changed from valve opening to valve closing. When at least one of the absolute values of the amount of change in the feedback amount is equal to or greater than a first threshold, it is determined that the reduction valve is abnormal.
Abnormality judgment device for weight reduction valve. In the abnormality determination device according to any one of claims 1 to 3,
The control unit is
In the second abnormality determination, when the absolute value of the change amount of the fuel pressure when the instruction to the reduction valve is changed from the closed valve to the opened valve, it is determined that the reduction valve is abnormal. ,
Abnormality judgment device for weight loss valve

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