阅读说明：本技术 高压燃料供给系统的溢流阀判定装置 (Relief valve determination device for high-pressure fuel supply system ) 是由 坂本由梨 金谷智洋 西尾贵史 于 2018-03-27 设计创作，主要内容包括：溢流阀判定装置(90)判定具备燃料喷射阀(62)、高压泵(30)、检测高压泵的排出侧的燃料压力的压力传感器(82)、以及在排出侧的燃料压力高于开阀压的情况下成为开状态以使排出侧的燃料压力降低至规定压的溢流阀(80)的高压燃料供给系统的溢流阀为开状态。溢流阀判定装置具备：推断部,假设从检测出的燃料压力由高于第1压力的状态变化为低于第1压力的状态的时刻起,通过高压泵未排出燃料,并基于燃料喷射阀的燃料的喷射量推断排出侧的燃料压力；以及判定部,基于推断出的燃料压力的下降形态及检测出的燃料压力的下降形态,判定为溢流阀为开状态。(A relief valve determination device (90) determines that a relief valve of a high-pressure fuel supply system, which is provided with a fuel injection valve (62), a high-pressure pump (30), a pressure sensor (82) that detects the fuel pressure on the discharge side of the high-pressure pump, and a relief valve (80) that is opened when the fuel pressure on the discharge side is higher than a valve opening pressure so that the fuel pressure on the discharge side is reduced to a predetermined pressure, is open. The relief valve determination device includes: an estimation unit that estimates a fuel pressure on a discharge side based on an injection amount of fuel from the fuel injection valve, assuming that no fuel is discharged from the high-pressure pump from a time point when the detected fuel pressure changes from a state higher than the 1 st pressure to a state lower than the 1 st pressure; and a determination unit that determines that the relief valve is open based on the estimated fuel pressure drop pattern and the detected fuel pressure drop pattern.)

1. A relief valve determination device (90) that determines that a relief valve (80) of a high-pressure fuel supply system is in an open state, the high-pressure fuel supply system being provided with a fuel injection valve (62) that injects fuel, a high-pressure pump (30) that pressurizes and discharges fuel to a supply path (44) that faces the fuel injection valve, a pressure sensor (82) that detects a fuel pressure on a discharge side of the high-pressure pump, and the relief valve that is in an open state when the fuel pressure on the discharge side is higher than a valve opening pressure and reduces the fuel pressure on the discharge side to a predetermined pressure, the relief valve determination device being characterized by comprising:

An estimation unit that estimates the fuel pressure on the discharge side based on the injection amount of the fuel from the fuel injection valve, assuming that the fuel is not discharged from the high-pressure pump from a time point when the fuel pressure detected by the pressure sensor changes from a state higher than a 1 st pressure set lower than the valve opening pressure to a state lower than the 1 st pressure; and

And a determination unit that determines that the relief valve is open based on a state of decrease in the fuel pressure estimated by the estimation unit and a state of decrease in the fuel pressure detected by the pressure sensor.

2. The overflow valve determining device according to claim 1,

The determination unit determines whether or not the relief valve is open at a timing when at least one of the fuel pressure estimated by the estimation unit and the fuel pressure detected by the pressure sensor is reduced to a 2 nd pressure that is set to be lower than the 1 st pressure.

3. The overflow valve determining device according to claim 2,

The determination unit determines whether or not the relief valve is open based on the time taken for the fuel pressure estimated by the estimation unit to decrease from the 1 st pressure to the 2 nd pressure and the time taken for the fuel pressure detected by the pressure sensor to decrease from the 1 st pressure to the 2 nd pressure, and estimates the time taken for the fuel pressure estimated by the estimation unit to decrease from the 1 st pressure to the 2 nd pressure at a timing when the fuel pressure detected by the pressure sensor decreases from the fuel pressure estimated by the estimation unit to the 2 nd pressure first.

4. An overflow valve judging device according to any one of claims 1 to 3,

the estimation unit estimates the fuel pressure on the discharge side so as to decrease faster than the actual fuel pressure on the discharge side even if the actual fuel pressure on the discharge side fluctuates when the spill valve is closed and the fuel is not discharged by the high-pressure pump.

5. The relief valve determining device according to claim 1 or 2,

The estimating unit estimates the fuel pressure on the discharge side so as to decrease faster than the actual fuel pressure on the discharge side even if the actual fuel pressure on the discharge side fluctuates when the spill valve is closed and the fuel is not discharged by the high-pressure pump,

The determination unit determines that the relief valve is open when a time during which the fuel pressure detected by the pressure sensor decreases from the 1 st pressure to a 2 nd pressure that is set to be lower than the 1 st pressure is shorter than a time during which the fuel pressure estimated by the estimation unit decreases from the 1 st pressure to the 2 nd pressure.

6. An overflow valve judging device according to any one of claims 1 to 5,

The estimation unit estimates the fuel pressure on the discharge side based on the injection amount of the fuel from the fuel injection valve, the bulk modulus of elasticity of the fuel, and the temperature of the fuel.

Technical Field

The present application relates to a device for determining that a relief valve of a high-pressure fuel supply system is open.

Background

Conventionally, there is a technique of feedback-controlling the discharge amount of a high-pressure pump so that the fuel pressure detected by a fuel pressure sensor matches a target fuel pressure, and determining the presence or absence of an abnormality in a high-pressure fuel supply system based on a comparison value between an integrated value of the discharge amount of the high-pressure pump and an integrated value of the fuel injection amount of a fuel injection valve during a predetermined period and the fuel pressure detected by the fuel pressure sensor (see patent document 1).

Disclosure of Invention

However, in the technique described in patent document 1, feedback control is performed on the discharge amount of the high-pressure pump, and for example, a case where the discharge amount of the high-pressure pump increases when fuel leakage occurs is used for determination. Therefore, the technique described in patent document 1 cannot determine whether or not there is an abnormality in the high-pressure fuel supply system without feedback control of the discharge amount of the high-pressure pump.

The present application has been made to solve the above-described problems, and a main object thereof is to provide a relief valve determination device capable of determining that a relief valve is in an open state even when the discharge amount of a high-pressure pump is not feedback-controlled.

The 1 st aspect for solving the above problems is a relief valve determining device,

a relief valve determination device that determines that a relief valve of a high-pressure fuel supply system is in an open state, the high-pressure fuel supply system including a fuel injection valve that injects fuel, a high-pressure pump that pressurizes and discharges fuel to a supply path toward the fuel injection valve, a pressure sensor that detects a fuel pressure on a discharge side of the high-pressure pump, and the relief valve that is in an open state when the fuel pressure on the discharge side is higher than a valve opening pressure and reduces the fuel pressure on the discharge side to a predetermined pressure, the relief valve determination device comprising:

An estimation unit that estimates the fuel pressure on the discharge side based on the injection amount of the fuel from the fuel injection valve, assuming that the fuel is not discharged by the high-pressure pump from a time point when the fuel pressure detected by the pressure sensor changes from a state higher than a 1 st pressure set lower than the valve opening pressure to a state lower than the 1 st pressure; and

And a determination unit that determines that the relief valve is open based on a state of decrease in the fuel pressure estimated by the estimation unit and a state of decrease in the fuel pressure detected by the pressure sensor.

According to the above configuration, the fuel is pressurized by the high-pressure pump and discharged to the supply path toward the fuel injection valve. And, the fuel is injected through the fuel injection valve. Further, the fuel pressure on the discharge side of the high-pressure pump is detected by a pressure sensor. When the fuel pressure on the discharge side of the high-pressure pump is higher than the valve opening pressure, the relief valve is opened, and the fuel pressure on the discharge side is reduced to a predetermined pressure.

here, the estimation unit estimates the fuel pressure on the discharge side based on the injection amount of the fuel from the fuel injection valve on the assumption that the fuel is not discharged from the high-pressure pump from the time when the fuel pressure detected by the pressure sensor changes from a state higher than the 1 st pressure which is set lower than the valve opening pressure to a state lower than the 1 st pressure. That is, when the fuel pressure on the discharge side decreases across the 1 st pressure, the fuel pressure on the discharge side that decreases only by fuel injection from the fuel injection valve is estimated in a state where the fuel is not discharged by the high-pressure pump. For example, when the relief valve is closed and the fuel is discharged by the high-pressure pump, the fuel pressure on the discharge side detected by the pressure sensor changes to be equal to or higher than the fuel pressure on the discharge side estimated by the estimation unit. In contrast, when the relief valve is in the open state, the fuel pressure on the discharge side detected by the pressure sensor changes so as to be lower than the fuel pressure on the discharge side estimated by the estimation unit, regardless of whether the fuel is discharged by the high-pressure pump.

therefore, the determination unit can determine that the relief valve is open based on the state of decrease in the fuel pressure estimated by the estimation unit and the state of decrease in the fuel pressure detected by the pressure sensor. Further, since the estimation unit estimates the fuel pressure on the discharge side on the assumption that the high-pressure pump does not discharge the fuel, it is not necessary to assume feedback control of the discharge amount of the high-pressure pump. Therefore, even when the discharge amount of the high-pressure pump is not feedback-controlled (when the feedback control does not operate normally), it can be determined that the relief valve is in the open state. In addition, when the discharge amount of the high-pressure pump is feedback-controlled, it can be similarly determined that the relief valve is open.

Drawings

The above and other objects, features and advantages of the present application will become more apparent with reference to the accompanying drawings and the following detailed description. The attached drawings are as follows:

FIG. 1 is a schematic view showing an engine and its peripheral constitution,

FIG. 2 is a diagram showing a change in fuel pressure with the relief valve being opened,

FIG. 3 is a flowchart showing the steps of the relief valve determination of embodiment 1,

FIG. 4 is a flowchart showing the procedure of calculation of the estimated time in embodiment 1,

Figure 5 is a graph showing the difference in actual fuel pressure,

FIG. 6 is a flowchart showing the procedure of actual measurement time calculation according to embodiment 1,

FIG. 7 is a graph showing the relationship between the degree of smoothness of the detected pressure and the detected pressure after the smoothness,

FIG. 8 is a timing chart showing an example of the operation of the relief valve determination of embodiment 1,

Fig. 9 is a flowchart showing the steps of the relief valve determination of embodiment 2,

FIG. 10 is a flowchart showing the procedure of calculation of the estimated time according to embodiment 2,

FIG. 11 is a sequence diagram showing a procedure of calculating the estimated time in embodiment 2,

FIG. 12 is a flowchart showing the procedure of actual measurement time calculation according to embodiment 2,

fig. 13 is a timing chart showing an operation example of the relief valve determination according to embodiment 2.

Detailed Description

(embodiment 1)

Hereinafter, embodiment 1 of a 4-cylinder gasoline engine (internal combustion engine) will be described with reference to the drawings.

As shown in fig. 1, the engine 10 includes a crankshaft 12 (drive shaft), a cam 14, a low-pressure pump 20, a high-pressure pump 30, a delivery pipe 60, a fuel injection valve 62, a relief valve 80, a pressure sensor 82, and the like. The cam 14 is driven by rotation of the crank shaft 12.

The low-pressure pump 20 sucks fuel in the fuel tank 18, and discharges the fuel after pressurization. The pressure of the fuel discharged by the low-pressure pump 20 is adjusted by a regulator (not shown) or the like.

the high-pressure pump 30 includes a cylinder 32, a plunger 34, a metering valve 36, a discharge valve 38, and the like.

a low pressure chamber 40 and a pressurizing chamber 42 are formed in the cylinder 32. The fuel discharged by the low-pressure pump 20 is supplied to a low-pressure chamber 40 (predetermined chamber) via a pipe 22. That is, the fuel discharged by the low-pressure pump 20 is accumulated in the low-pressure chamber 40. The low pressure chamber 40 and the pressurizing chamber 42 are connected via the metering valve 36. The volume control valve 36 switches between the cutoff and communication between the low pressure chamber 40 and the pressurizing chamber 42. The driving state of the metering valve 36 is controlled by an ECU (Electronic Control Unit) 90.

the plunger 34 is supported by the cylinder 32 so as to be movable back and forth. The plunger 34 is driven to reciprocate by the rotation of the cam 14. By the reciprocating movement of the plunger 34, fuel is drawn from the low pressure chamber 40 into the pressurizing chamber 42, and the fuel in the pressurizing chamber 42 is pressurized. The fuel pressurized in the pressurizing chamber 42 is discharged to a pipe 44 (corresponding to a supply path) via the discharge valve 38. Then, the fuel passes through the pipe 44 and is supplied to the delivery pipe 60 and further to the fuel injection valve 62. The discharge valve 38 is a check valve that allows fuel to flow only in the direction from the pressurizing chamber 42 to the pipe 44, and opens when the fuel pressure in the pressurizing chamber 42 becomes equal to or higher than a predetermined discharge pressure.

The delivery pipe 60 (pressure accumulation vessel) accumulates the fuel discharged by the high-pressure pump 30 in a pressurized state. The pressure sensor 82 detects the fuel pressure in the delivery pipe 60 (i.e., the discharge side of the high-pressure pump 30). The fuel pressure (hereinafter referred to as "detected pressure Pm") detected by the pressure sensor 82 is input to the ECU 90. The pressure sensor 82 may detect the fuel pressure in the pipe 44 or the fuel pressure in the fuel injection valve 62.

The relief valve 80 is opened (opened) when the fuel pressure in the delivery pipe 60 (pipe 44) is higher than the valve opening pressure, and returns the fuel in the delivery pipe 60 to the low pressure chamber 40. The valve opening pressure is set to be lower than the pressure resistance (rail pressure resistance) before degradation (aging) of the delivery pipe 60. The fuel pressure in the low pressure chamber 40 becomes a predetermined pressure lower than the fuel pressure in the pressurizing chamber 42. When relief valve 80 is once opened, the fuel pressure in delivery pipe 60 is maintained at about the fuel pressure (predetermined pressure) in low-pressure chamber 40.

Four fuel injection valves 62 are connected to the delivery pipe 60. Fuel injection valve 62 directly injects fuel in delivery pipe 60 into the cylinder of engine 10. The driving state of the fuel injection valve 62 is controlled by the ECU 90. The fuel injection valve 62, the delivery pipe 60, the pipe 44, the high-pressure pump 30, the pipe 22, the low-pressure pump 20, the pressure sensor 82, and the relief valve 80 constitute a high-pressure fuel supply system.

The ECU 90 (corresponding to relief valve determination means) is a microcomputer provided with a CPU, ROM, RAM, a drive circuit, an input/output interface, and the like. The ECU 90 is an engine ECU or the like that controls the operating state of the engine 10, and executes idle rotation speed control or the like that maintains the idle rotation speed of the engine 10 at a target idle rotation speed. ECU 90 controls the driving state of metering valve 36 (i.e., the discharge amount of high-pressure pump 30) so that detected pressure Pm matches the target fuel pressure.

Next, the operation of the high-pressure pump 30 will be explained.

(1) Suction stroke

The fuel pressure in the pressurizing chamber 42 is lowered by the plunger 34 being lowered, and the fuel is drawn from the low pressure chamber 40 into the pressurizing chamber 42. Then, the ECU 90 controls the metering valve 36 so as to maintain the valve-open state.

(2) Return stroke

in the state where the metering valve 36 is open, even if the plunger 34 is raised from the bottom dead center toward the top dead center, the fuel in the pressurizing chamber 42 pressurized by the plunger 34 returns to the low pressure chamber 40 via the metering valve 36.

(3) Pressure stroke

In the return stroke, the metering valve 36 is controlled to be closed by the ECU 90. In this state, when the plunger 34 further rises toward the top dead center, the fuel in the pressurizing chamber 42 is pressurized, and the fuel pressure rises. Then, when the fuel pressure in the pressurizing chamber 42 becomes equal to or higher than a predetermined discharge pressure, the discharge valve 38 is opened. The fuel discharged from the discharge valve 38 is supplied to the delivery pipe 60, accumulated in a pressurized state, and supplied to the fuel injection valve 62.

by repeating the strokes (1) to (3), the high-pressure pump 30 pressurizes and discharges the fuel sucked in. The amount of fuel discharged is adjusted by controlling the closing timing of the metering valve 36.

Fig. 2 is a diagram showing a change in fuel pressure with the relief valve 80 being opened. In this figure, the high-pressure pump 30 fails at time t11, and the fuel is continuously discharged at the maximum discharge amount. After time t11, the fuel pressure in delivery pipe 60 rises each time high-pressure pump 30 discharges fuel. At time t12, an upper pressure limit (injection control upper pressure limit) at which the injection by the fuel injection valve 62 can be controlled is reached. Thereafter, at time t13, the fuel pressure reaches the valve opening pressure of the relief valve 80, and the relief valve 80 is opened. When relief valve 80 is opened, the fuel pressure in delivery pipe 60 is lowered to the vicinity of the fuel pressure in low-pressure chamber 40, and the amount of fuel discharged and the amount of fuel returned through relief valve 80 are maintained at a pressure balanced with each other. The region where the fuel pressure is equal to or lower than the injection control upper limit pressure is a normal region, and the region where the fuel pressure is higher than the injection control upper limit pressure is an abnormal region.

when the detected pressure Pm detected by the pressure sensor 82 exceeds the injection control upper limit pressure, the ECU 90 controls the amount of fuel discharged from the high-pressure pump 30 to 0. When the detected pressure Pm is lower than the recovery pressure that is set lower than the injection control upper limit pressure, the ECU 90 resumes the control for matching the detected pressure Pm with the target fuel pressure. However, as shown in fig. 2, when the high-pressure pump 30 fails, even if the detected pressure Pm exceeds the injection control upper limit, the discharge amount of fuel by the high-pressure pump 30 cannot be controlled to 0. Therefore, the fuel pressure in the delivery pipe 60 rises to reach the valve opening pressure of the relief valve 80, and the relief valve 80 is opened.

Therefore, in the present embodiment, when the detection pressure Pm changes from a state higher than the 1 st pressure set lower than the valve opening pressure to a state lower than the first pressure, the ECU 90 determines whether the relief valve 80 is in the open state.

fig. 3 is a flowchart showing a procedure of determining a relief valve according to the present embodiment. This series of processes is executed by ECU 90.

first, it is determined whether or not the execution condition for the relief valve determination is satisfied (S10). Specifically, when the execution condition 2 including the execution condition 1 is satisfied, it is determined that the execution condition for the relief valve determination is satisfied. If the execution condition 2 is not satisfied, it is determined that the execution condition for the relief valve determination is not satisfied. The execution condition 1 is that the detection pressure Pm detected by the pressure sensor 82 exceeds a pressure FP0 which is set lower than the valve opening pressure of the relief valve 80. The execution condition 2 is that the detection pressure Pm is smaller than the start pressure FP1 (equivalent to the 1 st pressure) which is set lower than the pressure FP0 after the execution condition 1 is satisfied. The start pressure FP1 is set such that, even when the detected pressure Pm is lower than the fuel pressure acting on the relief valve 80, the detected pressure Pm becomes higher than the start pressure FP1 at the moment when the relief valve 80 is opened.

If it is determined in the determination of S10 that the execution condition for the relief valve determination is not satisfied (no in S10), the process of S10 is executed again. On the other hand, when it is determined in the determination of S10 that the condition for executing the relief valve determination is satisfied (YES in S10), the estimated time calculation (S11) and the actual measurement time calculation (S12) are executed in parallel. Further, after one of the estimated time calculation (S11) and the measured time calculation (S12) is executed, the other may be executed.

Fig. 4 is a flowchart showing the procedure of calculating the estimated time in the present embodiment. This series of processes is executed by ECU 90.

The detection pressure Pm detected by the pressure sensor 82 is set to an initial value of the estimated pressure Pe, and the count value cnt1 is set to 0 (S111). It is determined whether the estimated pressure Pe is equal to or higher than the end pressure FP2 (corresponding to the 2 nd pressure) which is set lower than the start pressure FP1 (S112). The end pressure FP2 is set so that the range from the start pressure FP1 to the end pressure FP2 corresponds to the range in which the detected pressure Pm linearly decreases when the relief valve 80 is in the open state.

When it is determined in S112 that the estimated pressure Pe is equal to or higher than the end pressure FP2 (yes in S112), the estimated pressure Pe is set to a pressure obtained by subtracting the drop amount Δ P from the estimated pressure Pe (S113). The amount of decrease Δ P is an amount by which the fuel pressure in delivery pipe 60 is decreased by one fuel injection by fuel injection valve 62, i.e., every 180 ° ca (Crank Angle). In short, assuming that fuel is not discharged by the high-pressure pump 30, the estimated pressure Pe is inferred based on the injection amount of fuel by the fuel injection valve 62. The decrease amount Δ P is calculated by the following equation.

ΔP＝q×K×A/V

In the above equation, q is the injection amount of the primary fuel by the fuel injection valve 62, K is the bulk modulus of the fuel, a is a parameter for adjusting the decreasing speed of the estimated pressure Pe, and V is the total volume of the pipe 44 and the delivery pipe 60. In the case where the volume of the pipe 44 can be ignored compared to the volume of the delivery pipe 60, the volume of the delivery pipe 60 may be set to V. The injection quantity q may be estimated using a command value of the fuel injected by the fuel injection valve 62, based on the detected pressure Pm and the valve opening time of the fuel injection valve 62, or based on a change in the detected pressure Pm. The bulk modulus K may be set in advance as the bulk modulus of the fuel to be used. The bulk modulus K may be corrected based on the temperature (detected value or standard value) of the fuel and the pressure of the fuel.

The parameter a is set as follows, taking into account the actual fuel pressure fluctuation in the delivery pipe 60. Fig. 5 is a diagram showing a difference in actual fuel pressure in delivery pipe 60. Here, a case will be described as an example where the discharge amount of the fuel by the high-pressure pump 30 is controlled to 0 (the fuel is not discharged by the high-pressure pump 30) after the fuel pressure exceeds the injection control upper limit pressure.

As shown by the alternate long and short dash lines in the figure, when the relief valve 80 is in the closed state, the rate at which the actual fuel pressure decreases by the injection of fuel fluctuates due to the viscosity (characteristics) of the fuel, the temperature, the individual difference of the fuel injection valve 62, and the like. When the relief valve 80 is closed and fuel is not discharged from the high-pressure pump 30, the ECU 90 sets the parameter a so that the estimated pressure Pe decreases faster than the actual fuel pressure even if the actual fuel pressure fluctuates. That is, when the relief valve 80 is closed and fuel is not discharged from the high-pressure pump 30, the ECU 90 estimates the estimated pressure Pe to decrease faster than the actual fuel pressure even if the actual fuel pressure fluctuates.

Therefore, when the relief valve 80 is in the closed state, the estimated pressure Pe always decreases faster than the actual fuel pressure even if the actual fuel pressure fluctuates. In other words, the time for the inferred pressure Pe to decrease from the starting pressure FP1 to the ending pressure FP2 is always shorter than the time for the actual fuel pressure to decrease from the starting pressure FP1 to the ending pressure FP 2. Further, in the case where the high-pressure pump 30 fails and the discharge amount of the fuel cannot be controlled to 0, the actual fuel pressure is higher than the fuel pressure shown by the chain line in the figure. Therefore, also in this case, the estimated pressure Pe always drops faster than the actual fuel pressure.

As shown by the broken line in the figure, when the relief valve 80 is in the open state, the actual rate of fuel pressure decrease also fluctuates depending on the viscosity (characteristics) of the fuel, the temperature, the individual difference of the fuel injection valve 62, and the like. However, in this case, since the relief valve 80 is in the open state, the actual fuel pressure always drops faster than the estimated pressure Pe. In other words, the time for the actual fuel pressure to decrease from the start pressure FP1 to the end pressure FP2 is always shorter than the time for the inferred pressure Pe to decrease from the start pressure FP1 to the end pressure FP 2. Further, in the case where the high-pressure pump 30 fails to control the discharge amount of fuel to 0, the actual fuel pressure is higher than the fuel pressure shown by the broken line in the figure. In this case, as long as the relief valve 80 is in the open state, the actual fuel pressure always drops faster than the estimated pressure Pe.

Returning to fig. 4, in S114, the count value cnt1 is set to a value obtained by adding 1 to the count value cnt1 (S114). After that, the process from S112 is executed again. Here, in the processing of S112 to S114, the processing of S112 and the processing of S114 are executed at a predetermined control cycle (for example, 1ms cycle), but the processing of S113 is executed at a 180℃ a cycle. Therefore, the count value cnt1 indicates an estimated time [ ms ] at which the estimated pressure Pe is equal to or greater than the end pressure FP 2.

When it is determined in S112 that the estimated pressure Pe is not equal to or higher than the end pressure FP2 (no in S112), an estimation f (flag) indicating whether or not the calculation of the estimated time is ended is set to 1 (S115). The initial value of the estimation f is 0, and when the estimation pressure Pe is equal to or higher than the end pressure FP2, the estimation f is 0. After that, the series of processes (END) is ended. The processing in S111 to S115 corresponds to the processing in the estimation unit.

fig. 6 is a flowchart showing the procedure of calculating the actual measurement time according to the present embodiment. This series of processes is executed by ECU 90.

The count value cnt2 is set to 0 (S121). It is determined whether or not the detected pressure Pm detected by the pressure sensor 82 is equal to or higher than the end pressure FP2 (corresponding to the 2 nd pressure) (S122).

If it is determined in S122 that the detected voltage Pm is equal to or greater than the end voltage FP2 (yes in S122), the count value cnt2 is set to a value obtained by adding 1 to the count value cnt2 (S123). After that, the process from S122 is executed again. Here, the processing in S122 and S123 is executed at a predetermined control cycle (for example, 1ms cycle). Therefore, the count value cnt2 represents the actual measurement time [ ms ] when the detected voltage Pm is equal to or greater than the end voltage FP 2.

Fig. 7 is a diagram showing a relationship between the degree of smoothing of the detected voltage Pm and the smoothed detected voltage Pmn. The solid line indicates the detection voltage Pm. When the detected voltage Pm is smoothed to 1/n, the smoothed detected voltage pmn (k) is expressed by the following expression.

Pmn(k)＝Pmn(k－1)×(1－1/n)+Pm×(1/n)

In the above equation, Pmn (k) is the current value of the smoothed detected pressure Pmn, Pmn (k-1) is the previous value of the smoothed detected pressure Pmn, and 1/n is a smoothing coefficient.

As shown in this figure, the smaller the smoothing coefficient (the stronger the smoothing degree), the later the smoothed detected voltage Pmn changes than the detected voltage Pm, and the lower the peak value of the smoothed detected voltage Pmn is than the peak value of the detected voltage Pm. Here, the higher the rotation speed of the engine 10, the higher the rising speed and the falling speed of the detection pressure Pm. Therefore, the higher the rotation speed of the engine 10, the larger the difference between the detected voltage Pm and the smoothed detected voltage Pmn. Therefore, in the processing of S111 in fig. 4 and the processing of S122 in fig. 6, when the detected voltage Pm is used to smooth for the purpose of suppressing the influence of the pulsation of the detected voltage Pm and the noise, the higher the rotation speed of the engine 10 is, the larger the smoothing coefficient can be (the smaller the degree of smoothing).

Returning to fig. 6, if it is determined in the determination of S122 that the detected pressure Pm is not equal to or greater than the end pressure FP2 (no in S122), the actual measurement f indicating whether or not the calculation of the actual measurement time has been completed is set to 1. The initial value of the actual measurement f is 0, and when the detection voltage Pm is equal to or higher than the end voltage FP2, the actual measurement f is 0. After that, the series of processes (END) is ended. In addition, the upper limit time for repeating the processing in S122 and S123 may be set, and when the time for repeating the processing in S123 and S124 exceeds the upper limit time, the processing in S13 in fig. 3 may be advanced while keeping the actual measurement f at 0.

Returning to fig. 3, in S13, it is determined whether or not f is estimated to be 1 and f is actually measured to be 1 (S13). In this determination, when it is determined that the estimated f is 1 and the actually measured f is 1 (yes in S13), it is determined whether or not a value obtained by subtracting the count value cnt2 from the count value cnt1 is larger than a determination value (S14). The determination value is set to 0 or a predetermined value larger than 0, for example.

in the determination at S14, when it is determined that the value obtained by subtracting the count value cnt2 from the count value cnt1 is larger than the determination value (yes at S14), the valve opening f indicating whether the relief valve 80 is open is set to 1. That is, when the time for the detected pressure Pm to decrease from the start pressure FP1 to the end pressure FP2 is shorter than the time for the estimated pressure Pe to decrease from the start pressure FP1 to the end pressure FP2, it is determined that the relief valve 80 is in the open state. In other words, when the detected pressure Pm changes to be smaller than the estimated pressure Pe, it is determined that the relief valve 80 is in the open state. In short, the relief valve 80 is determined to be in the open state based on the lowering pattern of the estimated pressure Pe and the lowering pattern of the detected pressure Pm. After that, the series of processes (END) is ended.

On the other hand, in the case where it is determined in the determination of S14 that the value obtained by subtracting the count value cnt2 from the count value cnt1 is not greater than the determination value (no in S14), the valve opening f is set to 0. That is, when the time for the detected pressure Pm to decrease from the start pressure FP1 to the end pressure FP2 is longer than the time for the estimated pressure Pe to decrease from the start pressure FP1 to the end pressure FP2, it is determined that the relief valve 80 is in the closed state. In other words, when the detected pressure Pm changes to be equal to or higher than the estimated pressure Pe, it is determined that the relief valve 80 is in the closed state. In short, the relief valve 80 is determined to be in the closed state based on the lowering state of the estimated pressure Pe and the lowering state of the detected pressure Pm. After that, the series of processes (END) is ended.

When it is determined at S13 that at least one of the estimated f and the measured f is not 1 (S13: no), the series of processes (END) is ended. The initial value of the valve opening f is 0, and in this case, the valve opening f is 0.

the processing at S11 corresponds to the processing as the estimation unit, and the processing at S13 to S16 corresponds to the processing as the determination unit.

Fig. 8 is a timing chart showing an operation example of the relief valve determination according to the present embodiment.

At time t21, high-pressure pump 30 fails, and detection pressure Pm detected by pressure sensor 82 starts to rise. At time t22, if the detected pressure Pm exceeds the pressure FP0, the execution condition 1 is satisfied. At time t23, when the fuel pressure acting on the relief valve 80 exceeds the valve opening pressure, the relief valve 80 is opened. Then, the detection voltage Pm starts to decrease.

At time t24, if the detected voltage Pm is smaller than the start voltage FP1, the execution condition 2 is satisfied. Therefore, the count values cnt1 (estimated time) and cnt2 (measured time) are calculated, and the count values cnt1 and cnt2 start to increase.

At time t25, when the detected voltage Pm is smaller than the end voltage FP2, the increase of the count value cnt2 ends and the actual measurement f becomes 1. At time t26, when the estimated pressure Pe is smaller than the end pressure FP2, the increase of the count value cnt1 ends and the estimated pressure f becomes 1. Then, it is determined that the value obtained by subtracting the count value cnt2 from the count value cnt1 is larger than the determination value, and the open valve f becomes 1. Thereby, the relief valve 80 is determined to be in the open state.

The present embodiment described in detail above has the following advantages.

The ECU 90 estimates the estimated pressure Pe on the discharge side of the high-pressure pump 30 based on the amount of fuel injection from the fuel injection valve 62, assuming that the fuel is not discharged by the high-pressure pump 30, from the time when the detected pressure Pm detected by the pressure sensor 82 changes from a state higher than the start pressure FP1 to a state lower than the start pressure FP 1. Here, when the relief valve 80 is in the open state, the detection pressure Pm changes to be smaller than the estimated pressure Pe regardless of whether fuel is discharged by the high-pressure pump 30. Therefore, ECU 90 can determine that relief valve 80 is in the open state based on the lowering pattern of estimated pressure Pe and the lowering pattern of detected pressure Pm.

Since the ECU 90 assumes that the estimated pressure Pe is estimated without discharging the fuel by the high-pressure pump 30, it is not necessary to assume feedback control of the discharge amount of the high-pressure pump 30. Therefore, even when the discharge amount of the high-pressure pump 30 is not feedback-controlled, it can be determined that the relief valve 80 is in the open state. In addition, when the discharge amount of the high-pressure pump 30 is feedback-controlled, it can be similarly determined that the relief valve 80 is open.

the actual fuel pressure on the discharge side of the high-pressure pump 30 fluctuates due to the characteristics of the fuel, the temperature, the individual difference of the fuel injection valves 62, and the like. In this regard, when the relief valve 80 is closed and fuel is not discharged from the high-pressure pump 30, the ECU 90 estimates the estimated pressure Pe to decrease faster than the actual fuel pressure on the discharge side even if the actual fuel pressure on the discharge side fluctuates. Therefore, even if the actual fuel pressure fluctuation on the discharge side is changed so that the detected pressure Pm becomes smaller than the estimated pressure Pe, it can be determined that the relief valve 80 is in the open state. On the other hand, when the detected pressure Pm changes to be equal to or higher than the estimated pressure Pe, it can be determined that the relief valve 80 is in the closed state.

Whether relief valve 80 is in the open state is determined based on the time when detected pressure Pm decreases from start pressure FP1 to end pressure FP 2. Therefore, compared to the configuration in which whether or not the relief valve 80 is in the open state is determined based on the detection pressure Pm, the influence of the variation in the fuel pressure can be made less likely.

When the time for the detected pressure Pm to decrease from the start pressure FP1 to the end pressure FP2 is shorter than the time for the estimated pressure Pe to decrease from the start pressure FP1 to the end pressure FP2, the ECU 90 can determine that the relief valve 80 is in the open state.

The estimated pressure Pe is estimated based on the injection amount of the fuel by the fuel injection valve 62, the bulk modulus K of the fuel, and the temperature of the fuel. Therefore, the estimated pressure Pe can be appropriately estimated according to the property and temperature of the fuel.

(embodiment 2)

Hereinafter, embodiment 2 will be described mainly focusing on differences from embodiment 1. In the present embodiment, ECU 90 determines whether relief valve 80 is in the open state at the time when at least one of estimated pressure Pe and detected pressure Pm is reduced to end pressure FP2 set lower than start pressure FP 1. Note that the same reference numerals are given to the same portions as those in embodiment 1, and detailed description thereof is omitted.

Fig. 9 is a flowchart showing a procedure of determining a relief valve according to the present embodiment. This series of processes is executed by ECU 90.

First, it is determined whether or not the execution condition for the relief valve determination is satisfied (S20). Specifically, it is determined that the condition for executing the relief valve determination is satisfied on the condition that the detected pressure Pm detected by the pressure sensor 82 has decreased across the start pressure FP1 (corresponding to the 1 st pressure).

if it is determined in the determination of S20 that the condition for executing the relief valve determination is not satisfied (no in S20), the process of S20 is executed again. On the other hand, when it is determined in the determination of S20 that the condition for executing the relief valve determination is satisfied (YES in S20), the estimated time calculation (S21) and the actual measurement time calculation (S22) are executed in parallel. Further, after one of the estimated time calculation (S21) and the measured time calculation (S22) is executed, the other may be executed.

Fig. 10 is a flowchart showing the procedure of calculating the estimated time in the present embodiment. This series of processes is executed by ECU 90.

The processing of S212 to S214 is the same as the processing of S112 to S114 of fig. 4.

In S215, it is determined whether or not the measured value f is 1 (S215). In this determination, if it is determined that the measured value f is not 1 (no in S215), the process of S212 is executed again. On the other hand, in this determination, when it is determined that the actual measurement f is 1 (yes in S215), an estimation f indicating whether or not the calculation of the estimation time is completed is set to 0. That is, since the calculation of the count value cnt1 (estimated time) is not completed, the estimation f is set to 0.

Next, the count value cnt1 is set to a value obtained by adding the count value est to the count value cnt1 (S217). The count value est is a value corresponding to a time from a time point when the actual measurement f becomes 1 (i.e., a time point when the detected pressure Pm becomes smaller than the end pressure FP 2) until the estimated pressure Pe becomes smaller than the end pressure FP 2. After that, the series of processes (END) is ended.

Fig. 11 is a sequence diagram showing a procedure of calculating the estimated time in the present embodiment. At time t31, if the detection voltage Pm drops across the start voltage FP1, the count value cnt1 starts to increase.

At time t32, if the detected voltage Pm is lower than the end voltage FP2, the actual measurement f becomes 1. At this time, the count value cnt1 is a value corresponding to the time t31 to t 32. Then, the count value est is calculated by the following equation.

est＝(60/2/NE)×(Ps－FP2)/ΔP

In the above equation, NE is the rotation speed [ rpm ] of the engine 10, Ps is the estimated pressure Pe at the time when the detected pressure Pm becomes lower than the end pressure FP2, and Δ P is the same amount of decrease as in embodiment 1. Here, in order to prevent NE from becoming 0, a lower limit (e.g., idle rotation speed) (lower limit guard) is set for NE. In order to prevent Δ P from becoming 0, a lower limit value (lower limit guard) is set for the fuel injection amount q when calculating Δ P. Specifically, the minimum injection amount that can be injected by the fuel injection valve 62 is set as the lower limit value of the injection amount q.

Returning to fig. 10, if it is determined in the determination at S212 that the estimated pressure Pe is not equal to or greater than the end pressure FP2 (no at S212), an estimation f indicating whether or not the calculation of the estimated time has ended is set to 1 (S218). After that, the series of processes (END) is ended. The processing in S211 to S218 corresponds to the processing as the estimation unit.

Fig. 12 is a flowchart showing a procedure of calculating the actual measurement time according to the present embodiment. This series of processes is executed by ECU 90.

the processing of S221 to S223 is the same as the processing of S121 to S123 of fig. 6.

In S224, it is determined whether the inference f is 1 (S224). In this determination, if it is determined that the estimation f is not 1 (no in S224), the process of S222 is executed again. On the other hand, in this determination, if it is determined that the estimated f is 1 (yes in S224), the actual measurement f indicating whether or not the calculation of the actual measurement time has been completed is set to 0. That is, since the calculation of the count value cnt2 (actual measurement time) is not completed, the actual measurement f is set to 0. After that, the series of processes (END) is ended.

when it is determined in S222 that the detected pressure Pm is not equal to or greater than the end pressure FP2 (no in S222), the actual measurement f is set to 1 (S226). After that, the series of processes (END) is ended.

Returning to fig. 9, in S23, it is determined whether or not f is estimated to be 1 and actually measured f is 0 (S23). If a negative determination is made in this determination (no in S23), the process proceeds to S24. The processing of S24 to S26 is the same as the processing of S14 to S16 of fig. 3.

On the other hand, when it is determined that the estimated value f is 1 and the actually measured value f is 0 in the determination of S23 (yes in S23), and when it is determined that the value obtained by subtracting the count value cnt2 from the count value cnt1 is not greater than the determination value in the determination of S24 (no in S24), the valve opening f indicating whether the relief valve 80 is in the open state is set to 0. After that, the series of processes (END) is ended. The processing at S21 corresponds to the processing as the estimation unit, and the processing at S23 to S26 corresponds to the processing as the determination unit.

Fig. 13 is a timing chart showing an operation example of the relief valve determination according to the present embodiment. Here, an operation example at time t41 and thereafter corresponding to time t24 in fig. 8 will be described.

At time t41, the execution condition is satisfied when the detection voltage Pm drops across the start voltage FP 1. Therefore, the count values cnt1 (estimated time) and cnt2 (measured time) are calculated, and the count values cnt1 and cnt2 start to increase.

At time t42, when the detected voltage Pm is smaller than the end voltage FP2, the increase of the count value cnt2 ends and the actual measurement f becomes 1. The count value cnt1 is set to a value obtained by adding a count value est to the count value cnt 1. Further, it is determined that the value obtained by subtracting the count value cnt2 from the count value cnt1 is larger than the determination value, and the open valve f becomes 1. Thereby, the relief valve 80 is determined to be in the open state. In addition, it is inferred that f remains 0.

The present embodiment described in detail above has the following advantages. Only the advantages different from those of embodiment 1 will be described here.

ECU 90 determines whether relief valve 80 is in the open state at the time when at least one of estimated pressure Pe and detected pressure Pm is reduced to end pressure FP2 which is set lower than start pressure FP 1. When the detected pressure Pm decreases to the end pressure FP2 more quickly than the estimated pressure Pe, it is determined that the relief valve 80 is in the open state. Therefore, it is possible to determine whether or not the relief valve 80 is open at the time when at least one of the estimated pressure Pe and the detected pressure Pm is reduced to the end pressure FP2, and if it is determined that the relief valve 80 is open, it is possible to perform Fail-safe (Fail-safe) processing or the like at an early stage.

When the detected pressure Pm decreases to the end pressure FP2 before the estimated pressure Pe, the time taken for the estimated pressure Pe to decrease from the start pressure FP1 to the end pressure FP2 is estimated, and whether or not the relief valve 80 is in the open state is determined. Therefore, when it is determined that the relief valve 80 is in the open state, it is possible to perform fail-safe processing and the like at an early stage.

The above embodiment can be modified as follows. The same components as those in the above embodiment are given the same reference numerals, and the description thereof is omitted.

The ECU 90 (corresponding to the determination unit) may determine that the relief valve 80 is in the open state when the detected pressure Pm first drops from the start pressure FP1 to the end pressure FP2, and may determine that the relief valve 80 is in the closed state when the estimated pressure Pe first drops from the start pressure FP1 to the end pressure FP 2.

The pressure FP0, the start pressure FP1, and the end pressure FP2 may be set according to the rotation speed of the engine 10.

instead of using the parameter a, the rate of decrease in the estimated pressure Pe may be adjusted by correcting at least one of the injection amount q, the volume V, and the bulk modulus K.

the fuel can also be returned from delivery pipe 60 to pipe 22 and fuel tank 18 by relief valve 80.

As the high-pressure pump 30, an electric high-pressure pump driven by a rotating electric machine may be used.

The engine 10 is not limited to a direct injection engine using gasoline as fuel, and may be a direct injection engine using ethanol or the like as fuel or a diesel engine having a common rail.

The present application has been described with reference to the embodiments, but it should be understood that the present application is not limited to the embodiments and the configurations. The present application also includes various modifications and modifications within the equivalent range. Further, the various combinations and forms may include only one element, and other combinations and forms not less than the element are also within the scope and spirit of the present invention.