JP2016011602A - Reduction valve abnormality determination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an abnormality determination device capable of independently determining whether a reduction valve is abnormal.SOLUTION: An abnormality determination device is applied to each fuel injection system that includes an injection valve, a pump discharging fuel, and a reduction valve capable of switchably supplying part of or all of the fuel discharged from the pump to the injection valve. The reduction valve is opened or closed in response to an indication from a control unit so as to supply part of the fuel of a pump discharge amount by being opened if a fuel demanded quantity from the injection valve is equal to or smaller than a lower limit quantity, and to supply all of the fuel of the pump discharge amount to the injection valve by being closed if the fuel demanded quantity is larger than the lower limit quantity. The control unit feedback-controls a fuel pressure, and determines whether the reduction valve is abnormal on the basis of at least one of a transition of a feedback amount when the closed reduction valve is indicated to be opened and a transition of a feedback amount when the open reduction valve is indicated to be closed. It is thereby possible to determine whether the reduction valve is abnormal while discriminating abnormality in the reduction valve from abnormality in the other member.

Description

  The present invention includes a fuel injection system having an injection valve that injects fuel, a pump that discharges fuel, and a reduction valve that can be switched to supply a part or all of the fuel discharged from the pump to the injection valve. The present invention relates to an abnormality determination device for a weight reduction valve, which is applied to the above.

  2. Description of the Related Art Conventionally, in a fuel injection system in which a reduction valve is provided on a fuel supply path that connects an injection valve and a pump, a control device that opens and closes the reduction valve while considering a discharge amount at which the pump can operate properly has been proposed. . For example, when one of the conventional control devices (hereinafter referred to as “conventional device”) determines that the pump discharge amount is below the “lower limit amount at which the pump can operate properly”, it opens the reduction valve ( At the same time, the pump discharge amount is increased so as to compensate for the amount of fuel discharged from the fuel supply path through the open reduction valve. Thereby, the conventional apparatus prevents the discharge amount of the pump from falling below the lower limit amount without changing the amount of fuel supplied to the injection valve (see, for example, Patent Document 1). Hereinafter, the internal combustion engine is simply referred to as “engine”.

JP 2013-231373 A

  By the way, the weight reducing valve generally has a mechanical opening / closing mechanism, and may be fixed to a peripheral member in the opened state or the closed state due to aged deterioration or the like. For example, when the reduction valve is fixed in the opened 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 (opening instruction) is given to the reduction valve. Hereinafter, the former abnormality is referred to as “open sticking abnormality”, and the latter abnormality is referred to as “closed sticking abnormality”.

  Such an abnormality affects, for example, parameters related to engine air-fuel ratio control (for example, various feedback amounts for maintaining the air-fuel ratio constant). Specifically, when the above-described abnormality occurs, even if an attempt is made to change the opening / closing state of the reduction valve (for example, even if an opening / closing instruction is given to the actuator that opens / closes the reduction valve), the actual reduction The open / close state of the valve does not change. As a result, unintended fluctuations occur in the amount of fuel supplied to the injection valve, and the above parameters also fluctuate. Therefore, it can be considered that the presence or absence of the abnormality described above can be determined by referring to the parameters.

  However, since parameters related to engine air-fuel ratio control are generally affected by members other than the reducing valve (for example, various members belonging to the engine intake system or fuel injection system), even if the parameters fluctuate. It is difficult to specify whether or not the fluctuation is caused by the abnormality of the weight reducing valve. In other words, it is generally difficult to distinguish and determine whether or not the weight reduction valve is abnormal and whether or not other members are abnormal.

  In view of the above problems, an object of the present invention is to provide an abnormality determination device that can independently determine whether or not a 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, and a "reduction valve" that can be switched to supply part or all of the fuel discharged from the pump to the injection valve, It is applied to a fuel injection system having a “control unit” that controls opening and closing of the reduction valve and determines whether or not the reduction valve is abnormal.

Furthermore, the weight reduction valve
When the fuel amount required in the injection valve is less than or equal to a predetermined lower limit amount, the valve is opened and a part of the discharged fuel is supplied to the injection valve, and the required fuel amount is less than the lower limit amount. When the value is larger, the valve is closed and opened and closed according to an instruction from the control unit so as to supply all of the discharged fuel to the injection valve.

Furthermore, the control unit
Feedback control of the pressure of fuel supplied to the injection valve (hereinafter referred to as “fuel pressure”), transition of the feedback amount when the valve opening is instructed when the reduction valve is closed, and When the reduction valve is open, it is configured to determine whether or not the reduction valve is abnormal based on at least one of the transition of the feedback amount when the valve closing is instructed.

  With the above configuration, the pump can be operated by “the amount of fuel required in the injection valve (request amount), the amount of fuel for controlling the fuel pressure (feedback amount), and the reduction valve when the reduction valve is open. An amount of fuel (discharge amount) corresponding to the sum of the fuel amount (correction amount) for supplementing the discharged amount and the amount of fuel is discharged. When the reduction valve is closed, the entire discharge amount is supplied to the injection valve (that is, fuel is not discharged through the reduction valve), so the “correction amount” is zero.

  When the reduction valve is “normal”, when a valve opening instruction (opening instruction) is given to the closed reduction valve, the reduction valve opens according to the instruction, so the fuel actually discharged through the reduction valve The amount (actual emission amount) matches the correction amount. Therefore, in this case, even if the discharge amount increases by the correction amount (the same amount of fuel is discharged as the increased amount is discharged), the fuel pressure does not change, so the feedback amount (except for the original fuel pressure control) It does not change. In other words, there is no substantial variation in the feedback amount before and after the instruction is given to the reduction valve. The same applies when a valve closing instruction (close instruction) is given to the open valve.

  On the other hand, if a “closed sticking abnormality” occurs in the weight reduction valve, even if a valve opening instruction (opening instruction) is given to the weight reduction valve that is closed, the weight reduction valve does not actually open. The actual discharge amount (zero because the reduction valve is closed and fixed) and the correction amount (a positive predetermined amount on the assumption that the reduction valve opens) do not match. Therefore, in this case, if the discharge amount increases by the correction amount (the increased amount of fuel is not discharged), the fuel pressure increases, so the feedback amount decreases (so as to offset the increase in fuel pressure). In other words, the feedback amount substantially fluctuates (decreases) before and after the instruction is given to the reduction valve.

  On the other hand, if an “open sticking abnormality” has occurred in the reducing valve, even if the closing instruction (close instruction) is given to the opened reducing valve, the reducing valve does not actually close. The amount of discharge (a positive predetermined amount because the reduction valve is closed and fixed) and the correction amount (zero assuming that the reduction valve is closed) do not match. Therefore, in this case, if the discharge amount decreases by the amount the correction amount returns to zero (the fuel continues to be discharged), the fuel pressure decreases, so the feedback amount increases (so as to offset the decrease in fuel pressure). In other words, the feedback amount substantially fluctuates (increases) before and after the instruction is given to the reduction valve.

  As described above, when the reduction valve is “abnormal”, the feedback amount fluctuates when an instruction to change the open / close state is given to the reduction valve. As can be understood from the above description, this fluctuation in the feedback amount is caused by an abnormality of the reduction valve in principle (except for an abnormality in the instruction system to the reduction valve). Therefore, `` Change in feedback amount when instructing valve opening when the reduction valve is closed, and Transition in feedback amount when instructing valve closing when the reduction valve is open. Based on “at least one of”, the abnormality determination of the weight reduction valve can be performed separately from the abnormality determination of other members.

  Therefore, the abnormality determination device of the present invention can independently determine whether or not the weight reduction valve is abnormal.

  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 control of the pump in the present invention (control using the sum of the requested amount, the feedback amount and the correction amount as the discharge amount) may be performed by the control unit, and a specific pump operation control unit other than the control unit. May do.

  Furthermore, the “feedback amount” for fuel pressure control may be a control amount based on the deviation between the target value and the actual value of the fuel pressure. For example, the proportional term based on the deviation and the integration based on the time integral value of the deviation It may be calculated to include at least one of a term and a differential term based on a time derivative value of the deviation.

1 is a schematic diagram of an abnormality determination device according to an embodiment of the present invention, a fuel injection system to which the device is applied, and an internal combustion engine equipped with the 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.

<Embodiment>
FIG. 1 shows an internal combustion engine 10 equipped with a fuel injection system (details will be described later) to which an abnormality determination device (hereinafter also referred to as “implementation device”) according to an embodiment of the present invention is applied. The schematic structure of is shown. The engine 10 is an in-cylinder injection / spark ignition type / four-cycle internal combustion engine.

  The engine 10 includes a fuel injection system (11 to 16), a cylinder block (21 to 25), a cylinder head (31 to 38), an intake system (41 to 44), an exhaust system (51 to 53), an accelerator pedal ( 61), an ignition key switch (62), various sensors (71 to 76), and an electronic control device 81.

  The fuel injection system includes an injection valve (injector) 11 that injects fuel into a cylinder, a delivery pipe 12 that injects high-pressure fuel into the injection valve 11, a fuel pump 13 that boosts the fuel and sends the fuel to the delivery pipe 12, and a fuel pump 13 A fuel tank 14 for supplying fuel to the fuel, a reduction valve 15 capable of switching supply of part or all of the fuel discharged from the fuel pump 13 to the injection valve 11, and the pressure of the fuel in the delivery pipe 12 (fuel pressure) ) Is measured.

  The fuel pump 13 is an electric pump that operates according to an instruction signal (specifically, a duty ratio of the operating voltage) of the electronic control device 81, and boosts the fuel supplied from the fuel tank 14 and converts the fuel to the instruction signal. A corresponding amount of fuel is discharged.

  The reduction valve 15 is provided on a fuel supply path connecting the fuel pump 13 and the injection valve 11 (more specifically, the delivery pipe 12), and an instruction signal (opening instruction or closing valve) of the electronic control unit 81 is provided. Is configured to open and close based on (instruction). Furthermore, when the valve 15 is “open” (open), 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 injection valve 11. On the other hand, when the reduction valve 15 is “closed” (closed), the fuel discharged from the fuel pump 13 is not discharged from the fuel supply path. That is, at this time, “all” of the fuel discharged from the fuel pump 13 is supplied to the injection valve 11.

  The operation of the fuel pump 13 and the reduction valve 15 will be described in more detail. The fuel pump 13 controls the fuel amount (fuel requirement amount) required in the injection valve 11 and the fuel pressure according to the instruction signal of the electronic control device 81. This is equivalent to the sum of the amount of fuel (feedback amount) for fuel and the amount of fuel for compensating for the amount discharged by the reducing valve 15 when the reducing valve 15 is open (correction amount when the reducing valve is opened). It operates to discharge an amount (fuel discharge amount) of fuel (see also the fuel pressure control routine of FIG. 2).

  However, when the amount of fuel discharged from the fuel pump 13 (fuel discharge amount) is equal to or less than a predetermined lower limit amount, the proportional relationship (linearity) between the operation amount of the fuel pump 13 and the fuel discharge amount is the fuel discharge amount. It becomes insufficient in terms of controlling the amount. As a result, in this case, there is a possibility that an amount of fuel corresponding to the instruction signal is not discharged.

  Therefore, when the electronic control unit 81 determines that the fuel amount (fuel requirement amount) required in the injection valve 11 is equal to or less than the lower limit amount, an instruction to “open” (open) the reduction valve 15 is given. To give to. Further, in accordance with this instruction, the electronic control unit 81 increases the fuel discharge amount of the fuel pump 13 by “an amount for supplementing the amount discharged by the reduction valve 15 (correction amount at the time of reduction valve opening)”. As a result, it is possible to prevent the fuel pump 13 from operating under a situation where the fuel discharge amount is equal to or less than the lower limit amount (see the fuel pressure control routine of FIG. 2).

  On the other hand, when the electronic control unit 81 determines that the required fuel amount is larger than the lower limit amount, the electronic control unit 81 gives an instruction to the “reducing valve 15” to “close” the reducing valve 15. . Further, in accordance with this instruction, the electronic control unit 81 stops increasing the fuel discharge amount by the correction amount at the time of opening of the reduction valve (sets the correction amount at the time of opening of the reduction valve to zero). As a result, the fuel pump 13 operates without considering the presence of the reduction valve 15 under the situation where the fuel discharge amount becomes larger than the lower limit amount (see the fuel pressure control routine of FIG. 2).

  Note that the amount of fuel discharged from the fuel pump 13 (fuel discharge amount) increases or decreases depending on the feedback amount for fuel pressure control, and therefore does not necessarily match the required fuel amount. Therefore, even if the fuel requirement amount is equal to or less than the lower limit amount, the fuel discharge amount may be larger than the lower limit amount. In this case, the fuel pump 13 operates properly without adding a correction amount at the time of opening the reduction valve. However, since the feedback amount changes from moment to moment depending on the operating state of the engine 10 and the like, in order to more reliably prevent the fuel pump 13 from operating in a situation where the fuel discharge amount is less than or equal to the lower limit amount, the “fuel requirement amount” Based on whether or not is less than the lower limit amount, the reduction valve 15 is opened and closed.

  The cylinder block portion includes a cylinder 21, a piston 22, a connecting rod 23, and a crankshaft 24. The inner wall surface of the cylinder 21, the upper surface of the piston 22, and the lower surface of the cylinder head portion define a combustion chamber 25. The cylinder head includes an intake port 31 communicating with the combustion chamber 25, an intake valve 32 for opening and closing the intake port 31, an intake camshaft 33 for driving the intake valve 32, an exhaust port 34 communicating with the combustion chamber 25, and an exhaust port 34. It has an exhaust valve 35 that opens and closes, an exhaust camshaft 36 that drives the exhaust valve 35, an ignition plug 37, and an igniter 38 that generates a high voltage applied to the ignition plug 37.

  The intake system includes an intake manifold 41 connected to each cylinder via an intake port 31, an intake pipe 42 connected to the intake manifold 41, an air cleaner 43 provided at an end of the intake pipe 42, and an opening area of the intake pipe 42. And a throttle valve actuator 44a that rotationally drives the throttle valve 44 in response to an instruction signal. The exhaust system has an exhaust manifold 51 connected to each cylinder via an exhaust port 34, an exhaust pipe 52 connected to the exhaust manifold 51, and an exhaust gas purification catalyst 53 provided in the exhaust pipe 52. Yes.

  The accelerator pedal 61 is operated by an operator of the engine 10 in response to an output request to the engine 10 or the like. The ignition key switch 62 is operated by an operator of the engine 10 when starting the engine 10. The engine 10 includes a cam position sensor 71, a crank position sensor 72, a water temperature sensor 73, an intake air temperature sensor 74, and air-fuel ratio sensors 75 and 76 as various sensors.

  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 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.

-Operation of the apparatus In the execution apparatus, the CPU executes the "fuel pressure control routine" shown in FIG. 2 and controls the fuel pressure by adjusting the fuel discharge amount of the fuel pump. Further, the CPU executes a “decreasing valve abnormality determination routine” shown in FIG. 3 to determine whether or not the reducing valve 15 is abnormal (whether an open sticking abnormality or a closed sticking abnormality has occurred).

  Specifically, the CPU executes the routine of FIG. 2 every time a predetermined time elapses. When the processing of this routine is started, the CPU proceeds from step 200 to step 205, and the amount of fuel injected from the injection valve 11 and consumed (the amount of fuel required in the injection valve 11. Fuel required amount) Finj (t) To decide. The required fuel amount Finj (t) is determined based on another routine (not shown) for determining the required fuel amount based on the operating state of the engine 10 or the like.

  Next, the CPU proceeds to step 210 to determine “whether the fuel requirement amount Finj (t) is equal to or less than a predetermined lower limit amount Finjth”. The lower limit amount Finjth is such that the fuel pump 13 does not operate properly when the fuel requirement amount Finj is less than or equal to the lower limit amount Finjth (specifically, there is a proportional relationship between the operation amount of the fuel pump 13 and the fuel discharge amount). This is an amount that may be insufficient. The lower limit amount Finjth is determined by a prior experiment or the like and stored in the RAM.

  For example, if the fuel requirement amount Finj (t) at the current time (time t) is equal to or less than the lower limit amount Finjth, the CPU determines “Yes” in step 210 and proceeds to step 215. In step 215, the CPU sets the correction amount Fvopen at the time of reduction valve opening to the value “correction amount Fd” corresponding to the amount of fuel discharged from the fuel supply path when the reduction valve 15 opens (opens). Is stored. The correction amount Fd is determined by a prior experiment or the like and stored in the RAM. Next, the CPU proceeds to step 220 and transmits an instruction to open (open) the reduction valve 15 to an actuator (not shown) that opens and closes the reduction valve 15.

  As described above, when the fuel requirement amount Finj (t) at the present time (time t) is equal to or less than the lower limit amount Finjth, the reduction valve 15 is opened (opened) and the reduction valve opening correction amount Fvopen is set to the value. A correction amount Fd is set.

  On the other hand, when the fuel requirement amount Finj (t) at the present time (time t) is larger than the lower limit amount Finjth, the CPU makes a “No” determination at step 210 to proceed to step 225. In step 225, the CPU stores zero in the value of the correction valve opening correction amount Fvopen. Next, the CPU proceeds to step 230 and transmits an instruction to close (close) the reduction valve 15 to an actuator (not shown) that opens and closes the reduction valve 15.

  As described above, when the fuel requirement amount Finj (t) at the present time (time t) is larger than the lower limit amount Finjth, the reduction valve 15 is closed (closed) and the value of the reduction valve opening correction amount Fvopen is obtained. Is set to zero.

  Hereinafter, for the sake of convenience, the description will be continued for the case where the reduction valve 15 is currently “opened” (opened) and the correction amount Fd is stored in the value of the reduction valve opening correction amount Fvopen. After the process of step 220, the CPU proceeds to step 235 to determine the fuel pressure control feedback amount Ffb (t) at the current time.

  Specifically, in step 235, the CPU determines the feedback amount Ffb (t) by proportional / integral control (PI control). In other words, the CPU acquires the actual value FPact (t) of the current fuel pressure based on the output value of the fuel pressure sensor 16, and calculates the deviation ΔFP (t) between the target value FPtgt (t) and the actual value FPact (t). calculate. Furthermore, the CPU calculates a proportional term FBp (t) of the feedback amount by multiplying the deviation ΔFP (t) by a predetermined gain Kp. The target value FPtgt (t) is determined based on another routine (not shown) for determining the target value based on the operating state of the engine 10 or the like. The gain Kp is an appropriate value determined by a prior experiment or the like, and is stored in the ROM.

  Further, 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 ( t) is calculated. The gain Kp is an appropriate value determined by a prior experiment or the like, and is stored in the ROM.

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

  After the process of step 235, the CPU proceeds to step 240, and adds the fuel requirement amount Finj (t), the feedback amount Ffb (t), and the reduction valve opening correction amount Fvopen, thereby adding a fuel pump. 13 calculates the fuel discharge amount Fout (t) to be discharged. Since the current value of the amount-of-reduction valve opening correction amount Fvopen is the correction amount Fd, the fuel discharge amount Fout (t) is more than the sum of the fuel requirement amount Finj (t) and the feedback amount Ffb (t). It is calculated as a value larger by Fd. The fuel discharge amount Fout (t) is a value greater than or equal to zero.

  Next, the CPU proceeds to step 245 and transmits an instruction signal to the fuel pump 13 so as to discharge the fuel with the fuel discharge amount Fout (t). Specifically, the CPU specifies a “duty ratio of the operating voltage of the fuel pump 13 corresponding to the fuel discharge amount Fout (t)” with reference to a map or the like stored in the ROM, and operates the duty ratio. An instruction to apply a working voltage to the fuel pump 13 is transmitted to a controller (so-called FPC, Fuel Pump Controller, not shown) that operates the fuel pump 13.

  Thereafter, the CPU proceeds to step 295 to end the present routine tentatively.

  Further, the CPU executes the routine of FIG. 3 every time a predetermined time elapses. When the processing of this routine is started, the CPU proceeds from step 300 to step 305 to determine whether or not a “determination execution condition” for determining abnormality of the reduction valve 15 is currently satisfied. The determination execution condition is a condition for ensuring that an abnormality determination result (step 335, step 345, or step 350) described later is correct. For example, one of the following (condition 1) to (condition 3) Or a plurality. In addition, the predetermined value in each condition mentioned above is determined by a prior experiment etc., and is stored in ROM.

(Condition 1)
The fuel pressure sensor 16, the actuator of the reduction valve 15, the water temperature sensor 73, the intake air temperature sensor 74, and the injection valve 11 are normal.
(Condition 2)
The cooling water temperature is equal to or higher than the predetermined value, the intake air temperature is equal to or higher than the predetermined value, and the reduction valve 15 is not forcibly operated for reasons other than the adjustment of the fuel discharge amount Fout (step 210, etc.). That's it.
(Condition 3)
The temperature of the air-fuel ratio sensors 75 and 76 is equal to or higher than the activation temperature, the value of the air-fuel ratio feedback amount is a value within a predetermined range, the fuel pressure target value FPtgt is less than the predetermined value, The total number of

  For example, if the determination execution condition is not satisfied at the present time, the CPU makes a “No” determination at step 305 to proceed to step 395 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, when the determination execution condition is satisfied at the present time, the CPU determines “Yes” in step 305 and proceeds to step 310. In step 310, the CPU determines whether or not an instruction to change the open / close state has been given to the reduction valve 15 at the present time (time t). Specifically, the CPU instructs that the reduction valve 15 is opened at the time (time t-1) when this routine was executed last time and closes the reduction valve 15 at the current time (time t). Or whether or not the reduction valve 15 is closed at the time (time t-1) when this routine was last executed and the reduction valve 15 is opened (opened) at the current time (time t). It is determined whether or not.

  For example, if there is no instruction to change the open / close state of the reduction valve 15 at the present time (that is, the state in which the reduction valve 15 is opened or closed), the CPU determines “No” in step 310. And the routine proceeds to step 395 to end the present routine tentatively. That is, also in this case, the abnormality determination of the reduction valve 15 is not performed.

  On the other hand, if an instruction to change the open / close state of the reduction valve 15 is given at the current time, the CPU makes a “Yes” determination at step 310 to proceed to step 315. In step 315, the CPU stores the feedback amount Ffb (t-1) (at time t-1) before the same instruction is stored in the RAM.

  Next, the CPU executes the processing of step 320 and step 325 to continuously acquire the feedback amount Ffb after the instruction over a predetermined time (annealing time ta), according to the following expression (1). The feedback amount (smoothing value) Ffba is calculated. Specifically, the CPU sequentially applies the feedback amount Ffb (t) to the following expression (1) during the period from the current time (time τ = t) to the time (t = t + ta) when the annealing time ta elapses. The value Ffba (τ) is calculated. In the following equation (1), 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 Ffba (τ) is zero.

Ffba (τ) = Ffba (τ−1) + (Ffb (τ) −Ffba (τ−1)) / N
... (1)

  Note that the CPU may be configured to perform the calculation of the above expression (1) only when the following (Condition 4) and (Condition 5) are satisfied in the calculation of the annealing value Ffba.

(Condition 4)
The control status that is an index indicating the operating state of the engine 10 is “normal operation” (for example, feedback operation is not performed).
(Condition 5)
Update of the feedback amount Ffb is permitted. That is, control using the integral term FBi is permitted, and addition or subtraction of the integral term FBi is not prohibited.

  The CPU proceeds to step 325 every time the process of step 320 is performed, and whether or not the annealing time ta has elapsed from the start of the annealing calculation (that is, time t) (that is, whether or not the current time is time t + ta). )). If the warming time ta has not yet elapsed at the present time, the CPU makes a “No” determination at step 325 to return to step 320 again and repeat the processing of the same step.

  When the annealing time ta elapses, the CPU makes a “Yes” determination at step 325 to proceed to step 330. In step 330, the CPU determines whether the absolute value of the difference between the smoothed value Ffba (t + ta) and the feedback amount Ffb (t−1) before the instruction stored in the RAM is equal to or larger than a predetermined threshold value Ffbth. Determine whether. The threshold value Ffbth is a value with which it can be determined that the weight reducing valve 15 is abnormal when the absolute value is equal to or greater than the threshold value Ffbth. The threshold value Ffbth is determined by a prior experiment or the like and stored in the RAM.

  If the absolute value is smaller than the threshold value Ffbth, the CPU makes a “No” determination at step 330 to proceed to step 335. In step 335, the CPU determines that “there is no abnormality in the weight reduction valve 15”. Thereafter, the CPU proceeds to step 395 to end the present routine tentatively.

  On the other hand, if the absolute value is greater than or equal to the threshold value Ffbth, the CPU makes a “Yes” determination at step 330 to proceed to step 340. In step 340, the CPU determines whether or not a valve opening instruction (opening instruction) is given to the reduction valve 15 at time t. If a valve opening instruction (open instruction) is given at time t, the CPU makes a “Yes” determination at step 340 to proceed to step 345. In step 345, the CPU determines that “closed sticking abnormality has occurred in the reduction valve 15”. Thereafter, the CPU proceeds to step 395 to end the present routine tentatively.

  On the other hand, if the valve closing instruction (close instruction) is given to the reduction valve 15 at time t, the CPU makes a “No” determination at step 340 to proceed to step 350. In step 350, the CPU determines that “an open sticking abnormality has occurred in the weight reduction valve 15”. Thereafter, the CPU proceeds to step 395 to end the present routine tentatively.

  As described above, the execution device determines whether or not the reduction valve 15 is abnormal based on the change in the feedback amount Ffb before and after the instruction to change the open / close state of the reduction valve 15 is made (open sticking abnormality or closed sticking abnormality is present). Whether or not it has occurred) is determined. Thereby, the implementation apparatus can distinguish the abnormality determination of the weight reduction valve 15 from the abnormality determination of other members.

<Summary of Embodiment>
As described above, the abnormality determination device (implementation device) according to the embodiment of the present invention is
Applied to a fuel injection system having an injection valve 11, a pump 13 for discharging fuel, and a reduction valve 15 capable of switching supply of a part or all of the fuel discharged from the pump to the injection valve 11, This is a reduction valve abnormality determination device including a control unit (specifically, a CPU of the electronic control device 81) that controls opening / closing of the reduction valve 15 and determines whether or not the reduction valve 15 is abnormal.

  Here, the reduction valve 15 opens and supplies part of the discharged fuel to the injection valve 11 when the fuel amount (fuel requirement amount Finj) required in the injection valve is equal to or less than a predetermined lower limit amount Finjth. (Step 220), when the requested fuel amount Finj is larger than the lower limit Finjth, the control unit 81 instructs to close the valve and supply all of the discharged fuel to the injector 11 (Step 230). Open and close according to.

  Further, the control unit 81 feedback-controls the pressure of the fuel supplied to the injection valve 11, and when the valve 15 is closed, the feedback amount transition Ffba when the valve opening is instructed, Based on at least one of the feedback amount transitions Ffba when the valve 15 is instructed to open when the valve 15 is open, it is determined whether or not the reduction valve 15 is abnormal (step 335, step 345, step 350),

<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 abnormality determination device of the present invention may employ proportional / integral / derivative control (PID control) instead of proportional / integral control (PI control) as a method for feedback control of the fuel pressure.

  Further, the execution device determines whether the weight reduction valve 15 is abnormal based on a comparison of feedback amounts (absolute value of the difference) before and after an instruction to change the open / close state of the weight reduction valve 15 (step 330). However, due to, for example, deterioration of the fuel injection system (11 to 16 in FIG. 1), the feedback amount Ffb (t−1) of the “previous” instruction is the limit value of the feedback amount Ffb (more than the feedback amount). When reaching the upper limit value or lower limit value that cannot be increased or decreased), the abnormality determination of the reduction valve 15 cannot be properly performed even if the feedback amount before and after the instruction is compared.

  Therefore, the abnormality determination device of the present invention determines whether or not the feedback amount (smoothing value) Ffba is a value suitable for the determination before the abnormality determination processing (between step 325 and step 330) in the implementation apparatus. You may have the step to do.

  Specifically, in the same step, when the feedback amount Ffba after the valve opening instruction (opening instruction) is equal to or less than a predetermined lower limit value (the limit value or a value near the limit value described above), the subsequent processing is performed. Without performing, it may be configured to determine that a closed sticking abnormality has occurred in the weight reduction valve 15. Further, in the same step, when the feedback amount Ffba after the valve closing instruction (closing instruction) is equal to or greater than a predetermined upper limit value (the above-described limit value or a value near the limit value), the subsequent processing is not performed. It may be configured to determine that an open sticking abnormality has occurred in the weight reduction valve 15.

  Further, the execution device is applied to a fuel injection system in which the injection valve 11 directly injects fuel into the cylinder of the engine 10 (that is, in-cylinder injection). However, the implementation apparatus may be applied to a fuel injection system that injects fuel into the intake port 31 of the engine 10 (that is, port injection).

DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 11 ... Injection valve, 12 ... Delivery pipe, 13 ... Fuel pump, 14 ... Fuel tank, 15 ... Reduction valve, 16 ... Fuel pressure sensor, 81 ... Electronic control apparatus

Claims (1)

Applied to a fuel injection system having an injection valve for injecting fuel, a pump for discharging fuel, and a reduction valve capable of switching supply of a part or all of the fuel discharged from the pump to the injection valve A reduction valve abnormality determination device comprising a control unit for controlling opening and closing of the reduction valve and determining whether or not the reduction valve is abnormal,
The weight reduction valve is
When the fuel amount required in the injection valve is less than or equal to a predetermined lower limit amount, the valve is opened and a part of the discharged fuel is supplied to the injection valve, and the required fuel amount is less than the lower limit amount. In response to an instruction from the control unit so as to close and supply all of the discharged fuel to the injector,
The controller is
The pressure of the fuel supplied to the injection valve is feedback controlled, and the change in the feedback amount when the valve opening is instructed when the valve is closed, and the valve is opened. Determining whether or not the reduction valve is abnormal based on at least one of the transition of the feedback amount when instructing the valve closing in the case,
Abnormality judgment device for weight reduction valve.

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