Overpressure valve determination device for high-pressure fuel supply system

Abstract

Overpressure valve determining device (90) configured to determine that an overpressure valve in a high-pressure fuel supply system is in an open state, the high-pressure fuel supply system comprising: a fuel injector (62) configured to inject fuel; a high-pressure pump (30) configured to compress the fuel and deliver the fuel to a supply path (44) directed towards the fuel injector; a pressure sensor (82) configured to detect fuel pressure on a pressure side of the high-pressure pump; and the pressure relief valve (80), which is configured to enter an open state when the fuel pressure on the pressure side is higher than a valve opening pressure, in order to reduce the fuel pressure on the pressure side to a predetermined pressure, the overpressure valve determining device includes: an estimation unit configured to estimate the fuel pressure on the pressure side based on a quantity of fuel injection by the fuel injector, starting from a point in time when the fuel pressure detected by the pressure sensor changes from a higher state than an initial pressure set lower than the valve opening pressure to a lower state, assuming that the fuel is not being delivered by the high-pressure pump; and a determination unit configured to determine, based on a take-off mode of the fuel pressure estimated by the estimation unit and a take-off mode of the fuel pressure detected by the pressure sensor, that the pressure relief valve is in the open state.

Description

Technical area

[0001] The present disclosure relates to an apparatus for determining that a pressure relief valve of a high pressure fuel supply system is in an open state. General state of the art

[0002] Conventionally, a known device controls the discharge amount of a high-pressure pump via feedback to adjust the fuel pressure detected by a fuel pressure sensor to a target fuel pressure 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 with a fuel injection valve during a predetermined period of time, and the fuel pressure detected by the fuel pressure sensor. This known device determines the presence / absence of an abnormality in a high-pressure fuel supply system via feedback (see Patent Literature 1).

[0003] US 2009 / 0 240 417 A1 and US 7 706 962 B2 disclose a fuel delivery device having a delivery line that supplies fuel to a fuel injection valve of an internal combustion engine. An electromagnetic relief valve releases fuel from the delivery line in response to an opening command and reduces the pressure of the fuel in the delivery line. A diagnostic device for the relief valve includes an electronic control unit that issues the opening command to the relief valve in response to a stop command to stop the engine. Based on the way the pressure of the fuel in the delivery line changes after the stop command is issued, the unit determines whether the relief valve is defective. This appropriately diagnoses whether the electromagnetic relief valve is defective.

[0004] DE 10 2014 213 494 A1 relates to a method for producing a permanent magnet, comprising the steps: (a) producing a mixture comprising - a powder of a magnetic material and - a binder composition which comprises at least one precursor compound for silicon oxide and at least one precursor compound of a further oxide, (b) molding the mixture into a green part; (c) thermally treating the green part to convert at least parts of the binder composition into the oxides, and (d) successively on or simultaneously with step (c) sintering the green part to form a glass, ceramic or glass-ceramic matrix from the oxides, which matrix embeds the particles of the magnetic material.The permanent magnet that can be produced by the process comprises cores of a permanent magnetic material with an average particle diameter of no more than 1 µm and a matrix of a diamagnetic or paramagnetic material in which the cores are embedded. Technical literature of the state of the artPatent literature

[0005] Patent Literature 1: Japanese Patent JP 3 610 894 B2 Summary of the invention

[0006] In the disclosure of Patent Literature 1, assuming that the discharge amount of the high-pressure pump is subjected to feedback control, the fact that, for example, the discharge amount of the high-pressure pump increases when a fuel leak occurs is used in the determination. Accordingly, the disclosure of Patent Literature 1 cannot determine the presence / absence of an abnormality in the high-pressure fuel supply system if the discharge amount of the high-pressure pump is not controlled via feedback.

[0007] The present disclosure is made to solve the above-described problem, and it is an object to provide a relief valve determining device configured to determine that the relief valve is in an open state even when the discharge amount of the high-pressure pump is not feedback-controlled.

[0008] According to one aspect of the present disclosure, a relief valve determining device is configured to determine that a relief valve in a high-pressure fuel supply system is in an open state. The high-pressure fuel supply system includes: a fuel injection valve configured to inject fuel; a high-pressure pump configured to compress fuel and discharge the fuel to a supply path directed toward the fuel injection valve; a pressure sensor configured to detect a fuel pressure on a pressure side of the high-pressure pump; and the relief valve configured to enter an open state when the fuel pressure on the pressure side is higher than a valve opening pressure to reduce the fuel pressure on the pressure side to a predetermined pressure.The relief valve determining device includes an estimation unit configured to estimate the fuel pressure on the pressure side based on an amount of fuel injection with the fuel injection valve from a time point at which the fuel pressure detected with the pressure sensor changes from a higher state than a first pressure set lower than the valve opening pressure to a lower state, assuming that the fuel is not discharged with the high-pressure pump. The relief valve determining device further includes a determination unit configured to determine that the relief valve is in the open state based on a decrease mode of the fuel pressure estimated with the estimation unit and a decrease mode of the fuel pressure detected with the pressure sensor.

[0009] According to the configuration described above, the fuel is compressed by the high-pressure pump and delivered to a supply path to the fuel injection valve. The fuel is then injected by the fuel injection valve. Furthermore, the fuel pressure on the pressure side of the high-pressure pump is detected by the pressure sensor. When the fuel pressure on the pressure side of the high-pressure pump is higher than the valve opening pressure, the relief valve opens, and the fuel pressure on the pressure side decreases to a predetermined pressure.

[0010] It should be noted that the estimation unit estimates the pressure-side fuel pressure based on the fuel injection amount with the fuel injection valve, assuming that the fuel is not discharged with the high-pressure pump, from a time point when the fuel pressure detected with the pressure sensor changes from a higher state than the first pressure set lower than the valve opening pressure to a lower state. That is, when the pressure-side fuel pressure drops below the first pressure in a state where the fuel is not discharged with the high-pressure pump, the falling pressure-side fuel pressure is estimated with only fuel injection with the fuel injection valve.For example, when the relief valve is closed and fuel is discharged by the high-pressure pump, the pressure-side fuel pressure detected by the pressure sensor changes while being equal to or higher than the pressure-side fuel pressure estimated by the estimation unit. Conversely, when the relief valve is open, regardless of whether fuel is discharged by the high-pressure pump or not, the pressure-side fuel pressure detected by the pressure sensor changes while being lower than the pressure-side fuel pressure estimated by the estimation unit.

[0011] Accordingly, the determination unit determines that the relief valve is in the open state based on the decrease mode of the fuel pressure estimated by the estimation unit and the decrease mode of the fuel pressure detected by the pressure sensor. Since the estimation unit estimates the fuel pressure on the discharge side under the assumption that the fuel is not discharged at the high-pressure pump, it is not necessary to perform the estimation under the assumption of feedback control of the discharge amount of the high-pressure pump. Accordingly, even when the discharge amount of the high-pressure pump is not controlled by feedback (when the feedback control is not operating normally), it is possible to determine that the relief valve is in the open state.It should be noted that with feedback control of the discharge quantity of the high pressure pump, it is equally possible to determine that the pressure relief valve is in the open state. Short description of the figures

[0012] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. In the drawings: Fig. 1 is a schematic diagram showing a machine and its peripheral configuration; Fig. 2 is a diagram showing a fuel pressure change when the pressure relief valve enters an open state; Fig. 3 is a flowchart showing a procedure of a pressure relief valve determination according to a first embodiment; Fig. 4 is a flowchart showing a procedure of an estimated time calculation according to the first embodiment; Fig. 5 is a diagram showing a variation of an actual fuel pressure; Fig. 6 is a flowchart showing a procedure of calculating an actual measurement time according to the first embodiment; Fig. 7 is a graph showing the relationship between a smoothing degree of the detection pressure and the smoothed detection pressure; Fig. 8 is a time chart showing an operation example according to the relief valve determination according to the first embodiment; Fig. 9 is a flowchart showing the procedure of the pressure relief valve determination according to a second embodiment; Fig. 10 is a flowchart showing the procedure of the estimated time calculation according to the second embodiment; Fig. 11 is a timing chart showing the flow of the estimated time calculation according to the second embodiment; Fig. 12 is a flowchart showing the procedure for calculating the actual measurement time according to the second embodiment; and Fig. 13 is a time chart showing the operation example according to the relief valve determination according to the second embodiment. Description of Embodiments (First Embodiment)

[0013] In the following, a first embodiment implemented as a four-cylinder gasoline engine (internal combustion engine) will be described with reference to the figures.

[0014] As in Fig. As shown in Figure 1, an engine 10 includes a crankshaft 12 (drive shaft), a cam 14, a low-pressure pump 20, a high-pressure pump 30, a supply line 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 crankshaft 12.

[0015] The low-pressure pump 20 draws fuel from a fuel tank 18, compresses the fuel, and discharges the fuel. The pressure of the fuel discharged by the low-pressure pump 20 is controlled by a regulator (not shown) or the like.

[0016] The high pressure pump 30 has a cylinder body 32, a piston 34, a flow control valve 36, a discharge valve 38 and the like.

[0017] A low-pressure chamber 40 and a pressure chamber 42 are formed in the cylinder body 32. The fuel discharged by the low-pressure pump 20 is supplied to the low-pressure chamber 40 (predetermined chamber) via a pipe 22. That is, the fuel discharged by the low-pressure pump 20 is stored in the low-pressure chamber 40. The low-pressure chamber 40 and the pressure chamber 42 are connected to each other via the flow control valve 36. The flow control valve 36 switches between an open and a closed state between the low-pressure chamber 40 and the pressure chamber 42. The drive state of the flow control valve 36 is controlled by an ECU (electronic control unit) 90.

[0018] The piston 34 is supported for reciprocating movement with the cylinder body 32. The piston 34 is driven and reciprocated by rotation of the cam 14.

[0019] During the reciprocating movement of the piston 34, the fuel is sucked from the low-pressure chamber 40 into the pressure chamber 42, and the fuel in the pressure chamber 42 is compressed. The fuel compressed in the pressure chamber 42 is discharged via the discharge valve 38 to a pipe 44 (corresponding to a supply path). The fuel is then supplied via the pipe 44 to the supply line 60 and the fuel injection valve 62. The discharge valve 38 corresponds to a check valve for supplying fuel in only one direction from the pressure chamber 42 to the pipe 44. The discharge valve 38 is opened when the fuel pressure in the pressure chamber 42 becomes equal to or higher than a predetermined discharge pressure.

[0020] The supply line 60 (accumulator) maintains the fuel discharged by the high-pressure pump 30 in a compressed state. The pressure sensor 82 detects the fuel pressure in the supply line 60 (i.e., on the discharge side of the high-pressure pump 30). The fuel pressure detected by the pressure sensor 82 (hereinafter referred to as "detection pressure Pm") is input to the ECU 90. Note that the pressure sensor 82 can detect the fuel pressure in the pipe 44 or the fuel pressure in the fuel injection valve 62.

[0021] The relief valve 80 is opened (enters an open state) when the fuel pressure in the supply line 60 (pipe 44) is higher than the valve opening pressure to return the fuel in the supply line 60 to the low-pressure chamber 40. The valve opening pressure is set to be lower than a resistance pressure (rail resistance pressure) before deterioration (fatigue) is caused in the supply line 60. The fuel pressure in the low-pressure chamber 40 corresponds to a predetermined pressure, which is lower than the fuel pressure in the pressure chamber 42. When the relief valve 80 is opened once, the fuel pressure in the supply line 60 is maintained around the fuel pressure in the low-pressure chamber 40 (predetermined pressure).

[0022] The supply line 60 is connected to four fuel injection valves 62. The fuel injection valve 62 injects the fuel in the supply line 60 directly into the cylinder of the engine 10. The driving state of the fuel injection valve 62 is controlled by the ECU 90. Note that the fuel injection valve 62, the supply line 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 the high-pressure fuel supply system.

[0023] The ECU 90 (corresponding to the relief valve determining device) is a microcomputer including a CPU, a ROM, a RAM, a driver circuit, an input / output interface, and the like. The ECU 90 corresponds to an engine ECU for controlling the operating state of the engine 10 or the like. The ECU 90 performs idle speed control to maintain an idle speed of the engine 10 at a target idle speed or the like. The ECU 90 controls the drive state of the flow control valve 36 (i.e., the discharge amount of the high-pressure pump 30) to bring the detection pressure Pm into conformity with the target fuel pressure.

[0024] The operation of the high pressure pump 30 is described below. (1) Intake or intake stroke

[0025] The fuel is sucked from the low-pressure chamber 40 into the pressure chamber 42 based on the lowering of the piston 34 and the reduction of the fuel pressure in the pressure chamber 42. Subsequently, the flow control valve 36 is controlled by the ECU 90 to maintain the valve opening state. (2) Blowback stroke

[0026] In the state where the flow control valve 36 is opened, the fuel in the pressure chamber 42 compressed by the piston 34 is returned to the low-pressure chamber 40 via the flow control valve 36 even if the piston 34 moves from the bottom dead center to the top dead center. (3) Compression stroke

[0027] In the blowback stroke, the flow control valve 36 is controlled by the ECU 90 to be opened. In this state, as the piston 34 continues to move toward the top dead center, the fuel in the pressure chamber 42 is compressed, and the fuel pressure rises. When the fuel pressure in the pressure chamber 42 becomes equal to or higher than the predetermined discharge pressure, the discharge valve 38 is opened. The fuel discharged from the discharge valve 38 is supplied to the supply line 60, then stored in the compressed state and supplied to the fuel injection valve 62.

[0028] By repeating the above-described cycles (1) to (3), the high-pressure pump 30 compresses the intake fuel and discharges the fuel. The discharge amount of the fuel is controlled by controlling the valve closing timing of the flow control valve 36.

[0029] Fig. 2 is a graph showing a fuel pressure change when the relief valve 80 enters the open state. In the figure, at time t11, the high-pressure pump 30 fails and enters a state where it continuously discharges fuel at the maximum amount. At and after time t11, the fuel pressure in the delivery pipe 60 increases with each discharge by the high-pressure pump 30. At time t12, the pressure becomes an upper limit pressure to which the injection can be controlled with the fuel injection valve 62 (upper limit pressure of injection control). Thereafter, at time t13, the fuel pressure reaches the valve opening pressure of the relief valve 80, and the relief valve 80 is in the open state.Since the relief valve 80 is in the open state, the fuel pressure in the supply line 60 drops to approximately the fuel pressure in the low-pressure chamber 40 and is maintained at a pressure equal to the fuel discharge amount and the blowback amount blown back through the relief valve 80. A range in which the fuel pressure is equal to or lower than the upper limit pressure of the injection control is a normal range. A range in which the fuel pressure is higher than the upper limit pressure of the injection control is an abnormal range.

[0030] The ECU 90 controls the fuel delivery amount with the high-pressure pump 30 to "0" when the detection pressure Pm detected by the pressure sensor 82 exceeds the upper limit pressure of the injection control. The ECU 90 resumes control to bring the detection pressure Pm into line with the target fuel pressure when the detection pressure Pm becomes lower than a feedback pressure set to be lower than the upper limit pressure of the injection control. Note that if the high-pressure pump 30 fails, even if the detection pressure Pm exceeds the upper limit pressure of the injection control, it is not possible to control the fuel delivery amount with the high-pressure pump 30 to "0" as shown in Fig. 2. Accordingly, the fuel pressure in the supply line 60 rises and becomes the valve opening pressure of the relief valve 80, and the relief valve 80 enters the open state.

[0031] In the present embodiment, when the detection pressure Pm changes from a higher state than the first pressure set lower than the valve opening pressure to a lower state, the ECU 90 determines whether the relief valve 80 is in the open state or not.

[0032] Fig. 3 is a flowchart showing a procedure for determining the pressure relief valve according to the present embodiment. This series of processing is performed by the ECU 90.

[0033] First, it is determined whether the execution condition for the relief valve determination is satisfied (S10). Specifically, if an execution condition 2 is satisfied with an execution condition 1, 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. As the execution condition 1, it is determined whether the detection pressure Pm detected with the pressure sensor 82 has exceeded a pressure FP0 set lower than the valve opening pressure of the relief valve 80. As the execution condition 2, it is determined whether, after the satisfaction of the execution condition 1, the detection pressure Pm has become lower than a start pressure FP1 (corresponding to the first pressure) set lower than the pressure FP0.The starting pressure FP1 is set so that the detection pressure Pm becomes higher than the starting pressure FP1 at a moment when the relief valve 80 has entered the open state, even if the detection pressure Pm is lower than the fuel pressure acting on the relief valve 80.

[0034] In the determination at S10, if it is determined that the execution condition for the relief valve determination is not met (S10: NO), the processing at S10 is performed again. On the other hand, in the determination at S10, if it is determined that the execution condition for the relief valve determination is met (S10: YES), the estimated time calculation (S11) and the actual measurement time calculation (S12) are performed in parallel. Note that there may be a configuration such that one calculation is performed from the estimated time calculation (S11) and the actual measurement time calculation (S12), and then the other calculation is performed.

[0035] Fig. 4 is a flowchart illustrating a flow of the estimated time calculation according to the present embodiment. This series of processing is performed by the ECU 90.

[0036] The detection pressure Pm detected by the pressure sensor 82 is set as an initial value of an estimated pressure Pe, and a counter cnt1 is set to "0" (S111). It is determined whether the estimated pressure Pe is equal to or higher than an end pressure FP2 (corresponding to the second pressure) 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 detection pressure Pm decreases linearly when the relief valve 80 enters the open state.

[0037] In the determination at S112, if it is determined that the estimated pressure Pe is equal to or higher than the final pressure FP2 (S112: YES), the estimated pressure Pe is set as a pressure obtained by subtracting a decrease amount ΔP from the estimated pressure Pe (S113). The decrease amount ΔP corresponds to an amount of decrease in the fuel pressure in the supply pipe 60 by one fuel injection with the fuel injection valve 62, that is, by 180°CA (crank angle). That is, assuming that the fuel is not discharged with the high-pressure pump 30, the estimated pressure Pe is estimated based on the amount of fuel injection with the fuel injection valve 62. The decrease amount ΔP is calculated using the following expression. ΔP=q×K×A / V

[0038] In the above expression, q corresponds to a fuel injection amount at one time with the fuel injection valve 62. K is a Young's modulus of the fuel. A is a parameter for controlling the decreasing speed of the estimated pressure Pe. V is a total volume of the piping 44 and the delivery pipe 60. Note that the volume of the delivery pipe 60 may be V if the volume of the piping 44 compared to the volume of the delivery pipe 60 can be ignored. As the injection amount q, a command value of the fuel injected with the fuel injection valve 62 may be used. Otherwise, the injection amount may be estimated based on the detection pressure Pm and the valve opening time of the fuel injection valve 62, or it may be estimated based on a change in the detection pressure Pm. As the Young's modulus K, the Young's modulus of the fuel to be used may be set in advance.It should be noted that the elastic modulus K can be corrected according to the fuel temperature (detection value or standard value) or the fuel pressure.

[0039] The parameter A is set as follows, taking into account a variation or fluctuation of the actual fuel pressure in the supply line 60. Fig. 5 is a graph illustrating the variation of the actual fuel pressure in the delivery line 60. Here, an example is described in which the fuel pressure exceeds the upper limit pressure of the injection control, and then the fuel discharge amount is controlled to "0" by the high-pressure pump 30 (the fuel is not discharged by the high-pressure pump 30).

[0040] As indicated by a long-dashed, short-dashed line in the figure, when the relief valve 80 is in the closed state, the decreasing speed of the actual fuel pressure during fuel injection changes due to the viscosity (property) or temperature of the fuel, the individual difference of the fuel injection valve 62, or the like. The ECU 90 sets the parameter A so that when the relief valve 80 is in the closed state and the fuel is not discharged with the high-pressure pump 30, the estimated pressure Pe decreases faster than the actual fuel pressure, even though the actual fuel pressure varies.That is, the ECU 90 estimates the estimated pressure Pe so that the estimated pressure decreases faster than the actual fuel pressure when the relief valve 80 is in the closed state and the fuel is not discharged with the high-pressure pump 30, although the actual fuel pressure varies.

[0041] When the relief valve 80 is in the closed state, the estimated pressure Pe always decreases faster than the actual fuel pressure even though the actual fuel pressure varies. In other words, the time for the estimated pressure Pe to decrease from the starting pressure FP1 to the final pressure FP2 is always shorter than the time for the actual fuel pressure to decrease from the starting pressure FP1 to the final pressure FP2. Furthermore, when the high-pressure pump 30 fails and the fuel discharge amount is not controlled to "0", the actual fuel pressure is higher than the fuel pressure indicated by the long-dashed, short-dashed line in the figure. Accordingly, in this case, the estimated pressure Pe always decreases faster than the actual fuel pressure.

[0042] As indicated by a dashed line in the figure, when the relief valve 80 is open, the decreasing speed of the actual fuel pressure also varies due to the viscosity (property) or temperature of the fuel, the individual difference of the fuel injection valve 62, or the like. Note that in this case, since the relief valve 80 is in the open state, the actual fuel pressure always decreases faster than the estimated pressure Pe. In other words, the time in which the actual fuel pressure decreases from the start pressure FP1 to the final pressure FP2 is always shorter than the time in which the estimated pressure Pe decreases from the start pressure FP1 to the final pressure FP2. Furthermore, when the high-pressure pump 30 fails and the fuel discharge amount is not controlled to "0", the actual fuel pressure is higher than the fuel pressure indicated by the dashed line in the figure.In this case, when the relief valve 80 is in the open state, the actual fuel pressure always decreases faster than the estimated pressure Pe.

[0043] With reference to Fig. 4, at S114, the counter cnt1 is set to a value obtained by adding "1" to the counter cnt1 (S114). After that, the process starts again from the processing at S112. Note that in the processing at S112 to S114, the processing at S112 and the processing at S114 are performed at a predetermined control period (e.g., a period of 1 ms). The processing at S113 is performed at a period of 180°CA. Accordingly, the counter cnt1 represents an estimation time [ms] at which the estimated pressure Pe is equal to or higher than the final pressure FP2.

[0044] In the determination at S112, if it is determined that the estimated pressure Pe is not equal to or higher than the final pressure FP2 (S112: NO), an estimate f (flag) indicating whether the estimation time calculation has been completed is set to "1" (S115). Note that the initial value of the estimate f is "0". If the estimated pressure Pe is equal to or higher than the final pressure FP2, the estimate f is "0". After that, this series of processing is ended (END). Note that the processing at S111 to S115 corresponds to the processing as the estimation unit.

[0045] Fig. 6 is a flowchart showing a flow of calculating the actual measurement time according to the present embodiment. This series of processing is performed by the ECU 90.

[0046] A counter cnt2 is set to "0" (S121). It is determined whether the detection pressure Pm detected by the pressure sensor 82 is equal to or higher than the final pressure FP2 (corresponding to the second pressure) (S122).

[0047] In the determination at S122, if it is determined that the detection pressure Pm is equal to or higher than the final pressure FP2 (S122: YES), the counter cnt2 is set to a value obtained by adding "1" to the counter cnt2 (S123). Thereafter, the process restarts from the processing at S122. Note that the processing at S122 and S123 is performed at a predetermined control period (e.g., a period of 1 ms). Accordingly, the counter cnt2 represents an actual measurement time [ms] at which the detection pressure Pm is equal to or higher than the final pressure FP2.

[0048] Fig. Figure 7 is a graph showing the relationship between the smoothing degree of the detection pressure Pm and the smoothed detection pressure Pmn. The solid line indicates the detection pressure Pm. When the detection pressure Pm is smoothed to 1 / n, the smoothed detection pressure Pmn (k) is represented by the following expression. Pmn(k)=Pmn(k−1)×(1−1 / n)+Pm ×(1 / n)

[0049] In the above expression, Pmn (k) is a current value of the smoothed detection pressure Pmn. Pmn (k-1) is a previous value of the smoothed detection pressure Pmn. 1 / n is a smoothing coefficient.

[0050] As shown in the figure, when the smoothing coefficient is smaller (the smoothing degree is higher), the smoothed detection pressure Pmn changes behind the detection pressure Pm, and the peak of the smoothed detection pressure Pmn is lower than the peak of the detection pressure Pm. It should be noted that the higher the engine speed of the engine 10, the higher the increase speed and decrease speed of the detection pressure Pm. Accordingly, the higher the engine speed of the engine 10, the greater the difference between the detection pressure Pm and the smoothed detection pressure Pmn. Accordingly, there may be a configuration that, in the processing at S111 in Fig. 4 and processing at S122 in Fig. 6, when the detection pressure Pm is smoothed and used for the purpose of suppressing a pulse and noise influence on the detection pressure Pm, the higher the engine speed of the engine 10, the larger the smoothing coefficient is (the smoothing degree is weakened).

[0051] With reference to Fig. 6. In the determination at S122, if it is determined that the detection pressure Pm is not equal to or higher than the final pressure FP2 (S122: NO), an actual measurement f indicating whether the calculation of the actual measurement time has been completed is set to "1". Note that the initial value of the actual measurement f is "0". If the detection pressure Pm is equal to or higher than the final pressure FP2, the actual measurement f is "0". After that, this series of processing is ended (END). Furthermore, it can be configured that an upper limit time is set for repeating the processing at S122 and S123. If the time for repeatedly performing the processing at S123 and S124 exceeds the upper limit time, the process proceeds to processing at S13. Fig. 3, while the actual measurement f is equal to “0”.

[0052] With reference to Fig. 3, at S13, it is determined whether estimate f = 1 and actual measurement f = 1 (S13). In this determination, if it is determined that estimate f = 1 and actual measurement f = 1 (S13: YES), it is determined whether a value obtained by subtracting counter cnt2 from counter cnt1 is greater than a determination value (S14). The determination value is set to "0" or a predetermined value greater than "0."

[0053] In the determination at S14, in the case of determining that the value obtained by subtracting the counter cnt2 from the counter cnt1 is larger than the determination value (S14: YES), a valve opening f indicating whether or not the relief valve 80 is in the open state is set to "1". That is, when the time in which the detection pressure Pm decreases from the start pressure FP1 to the end pressure FP2 is shorter than the time in which the estimated pressure Pe decreases 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 detection pressure Pm changes while being lower than the estimated pressure Pe, it is determined that the relief valve 80 is in the open state. In short, it is determined based on the drop orThe sampling mode of the estimated pressure Pe and the sampling mode of the detection pressure Pm determine that the relief valve 80 is in the open state. After that, this series of processing is terminated (END).

[0054] On the other hand, in the determination at S14, if it is determined that the value obtained by subtracting the counter cnt2 from the counter cnt1 is not larger than the determination value (S14: NO), the valve opening f is set to "0." That is, when the time for the detection 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 detection pressure Pm changes while being equal to or higher than the estimated pressure Pe, it is determined that the relief valve 80 is in the closed state. In short, it is determined that the relief valve 80 is in the closed state based on the decrease mode of the estimated pressure Pe and the decrease mode of the detection pressure Pm.This processing sequence is then terminated (END).

[0055] Furthermore, in the determination at S13, if it is determined that the estimated value f and / or the actual measurement f is / are not equal to "1" (S13: NO), this processing sequence is terminated (END). Note that the initial value of the valve opening f is equal to "0." In this case, the valve opening f is equal to "0."

[0056] It should be noted that 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.

[0057] Fig. 8 is a time chart showing an operation example according to the relief valve determination according to the present embodiment.

[0058] At time t21, the high-pressure pump 30 fails, and the detection pressure Pm detected by the pressure sensor 82 begins to rise. At time t22, when the detection pressure Pm exceeds the pressure FP0, execution condition 1 is met. At time t23, when the fuel pressure acting on the relief valve 80 exceeds the valve opening pressure, the relief valve 80 enters the open state. Subsequently, the detection pressure Pm begins to decrease.

[0059] At time t24, when the detection pressure Pm becomes lower than the start pressure FP1, execution condition 2 is satisfied. Accordingly, the calculation of the counter cnt1 (estimation time) and the counter cnt2 (actual measurement time) is started, and the incrementation of the counter cnt1 and the counter cnt2 is started.

[0060] At time t25, when the detection pressure Pm becomes lower than the final pressure FP2, the incrementation of the counter cnt2 stops, and the actual measurement f becomes "1." At time t26, when the estimated pressure Pe becomes lower than the final pressure FP2, the incrementation of the counter cnt1 stops, and the estimate f becomes "1." Subsequently, if it is determined that the value obtained by subtracting the counter cnt2 from the counter cnt1 is greater than the determination value, the valve opening f becomes "1." With this configuration, it is determined that the relief valve 80 is in the open state.

[0061] The present embodiment, as described in detail above, has the following advantages.

[0062] - Assuming that the fuel has not been discharged with the high-pressure pump 30, from a time point at which the detection pressure Pm detected with the pressure sensor 82 changes from the higher state than the start pressure FP1 to the lower state, 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 with the fuel injection valve 62. Note that in the open state of the relief valve 80, the detection pressure Pm changes while being lower than the estimated pressure Pe regardless of whether the fuel is discharged with the high-pressure pump 30 or not. Accordingly, the ECU 90 determines that the relief valve 80 is in the open state based on the decrease mode of the estimated pressure Pe and the decrease mode of the detection pressure Pm.

[0063] The ECU 90 estimates the estimated pressure Pe under the assumption that the fuel is not discharged by the high-pressure pump 30. Therefore, it is not necessary to perform the estimation under the assumption of feedback control of the discharge amount by the high-pressure pump 30. Accordingly, even when the discharge amount is not controlled by feedback by the high-pressure pump 30, it is possible to determine that the relief valve 80 is in the open state. Note that, in the case of feedback control of the discharge amount by the high-pressure pump 30, it is equally possible to determine that the relief valve 80 is in the open state.

[0064] The actual fuel pressure on the discharge side of the high-pressure pump 30 varies due to the property or temperature of the fuel, the individual difference of the fuel injection valve 62, or the like. At this point, when the relief valve 80 is in the closed state and the fuel is not discharged with the high-pressure pump 30 even though the actual fuel pressure on the discharge side varies, the ECU 90 estimates the estimated pressure Pe so that the estimated pressure Pe decreases faster than the actual fuel pressure on the discharge side. Accordingly, even though the actual fuel pressure on the discharge side varies, if the detection pressure Pm changes while being lower than the estimated pressure Pe, it can be determined that the relief valve 80 is in the open state.On the other hand, if the detection pressure Pm changes while being equal to or higher than the estimated pressure Pe, it can be determined that the relief valve 80 is in the closed state.

[0065] - Based on the time at which the detection pressure Pm drops from the start pressure FP1 to the final pressure FP2, it is determined whether the relief valve 80 is in the open state or not. Accordingly, compared to the configuration in which it is determined based on the detection pressure Pm whether the relief valve 80 is in the open state or not, it is possible to suppress the influence of a variation in fuel pressure.

[0066] - When the time in which the detection pressure Pm decreases from the start pressure FP1 to the end pressure FP2 is shorter than the time in which the estimated pressure Pe decreases from the start pressure FP1 to the end pressure FP2, the ECU 90 determines that the relief valve 80 is in the open state.

[0067] - The estimated pressure Pe is estimated based on the amount of fuel injection by the fuel injection valve 62, the elastic modulus K of the fuel, and the fuel temperature. Accordingly, it is possible to appropriately estimate the estimated pressure Pe according to the property or temperature of the fuel. (Second embodiment)

[0068] A second embodiment will be described below mainly with reference to the difference from the first embodiment. In the present embodiment, the ECU 90 determines whether the relief valve 80 is in the open state or not when the estimated pressure Pe and / or the detection pressure Pm decreases to the final pressure FP2, which is set lower than the starting pressure FP1. Note that the elements similar to those in the first embodiment bear the same reference numerals, and detailed explanations are omitted.

[0069] Fig. 9 is a flowchart showing the relief valve determination procedure according to the present embodiment. This series of processing is performed by the ECU 90.

[0070] First, it is determined whether the execution condition of the relief valve determination is satisfied (S20). Specifically, assuming that the detection pressure Pm detected by the pressure sensor 82 drops below the start pressure FP1 (corresponding to the first pressure), it is determined that the execution condition of the relief valve determination is satisfied.

[0071] In the determination at S20, if it is determined that the execution condition of the relief valve determination is not met (S20: NO), the processing at S20 is performed again. On the other hand, in the determination at S20, if it is determined that the execution condition of the relief valve determination is met (S20: YES), the estimated time calculation (S21) and the actual measurement time calculation (S22) are performed in parallel. Note that there may be a configuration such that one calculation is performed from the estimated time calculation (S21) and the actual measurement time calculation (S22), and then the other calculation is performed.

[0072] Fig. 10 is a flowchart showing the estimated time calculation procedure according to the present embodiment. This series of processing is performed by the ECU 90.

[0073] The processing for S212 to S214 is the same as the processing for S112 to S114.

[0074] At S215, it is determined whether the actual measurement f is equal to "1" or not (S215). In this determination, if it is determined that the actual measurement f is not equal to "1" (S215: NO), the process restarts from the processing at S212. On the other hand, in this determination, if it is determined that the actual measurement f is equal to "1" (S215: YES), the estimate f indicating whether the estimated time calculation has been completed is set to "0." That is, since the calculation of the counter cnt1 (estimated time) has not yet been completed, the estimate f is set to "0."

[0075] Next, the counter cnt1 is set to a value obtained by adding a counter est to the counter cnt1 (S217). The counter est corresponds to a value corresponding to a period from a time point when the actual measurement f becomes 1 (i.e., the detection pressure Pm becomes lower than the final pressure FP2) to a time point when the estimated pressure Pe becomes lower than FP2. After that, this series of processing is terminated (END).

[0076] Fig. 11 is a timing chart showing the estimation time calculation flow according to the present embodiment. At time t31, when the detection pressure Pm falls below the start pressure FP1, the counter cnt1 starts incrementing.

[0077] At time t32, when the detection pressure Pm becomes lower than the final pressure FP2, the actual measurement f becomes "1." At this time, the counter cnt1 corresponds to a value corresponding to the time t31 to t32. Subsequently, the counter est is calculated using the following expression. est=(60 / 2 / NE)×(Ps−FP2) / ΔP

[0078] In the above expression, NE corresponds to an engine speed [rpm] of the engine 10. Ps is the estimated pressure Pe when the detection pressure Pm becomes lower than the final pressure FP2. ΔP is a decrease amount, which is the same as that in the first embodiment. Note that in order to prevent the engine speed NE from changing to "0", a lower limit value (e.g., idling speed) of the engine speed NE is set (lower limit protection). Further, in order to prevent the decrease amount ΔP from changing to "0", a lower limit value of the fuel injection amount q is set in the calculation of ΔP (lower limit protection). Specifically, a minimum injection amount that can be injected with the fuel injection valve 62 is set as the lower limit value of the injection amount q.

[0079] With reference to Fig. 10, in the determination at S212, if it is determined that the estimated pressure Pe is not equal to or higher than the final pressure FP2 (S212: NO), the estimate f indicating whether the estimated time calculation has been completed is set to "1" (S218). After that, this series of processing is ended (END). Note that the processing at S211 to S218 corresponds to the processing as the estimation unit.

[0080] Fig. 12 is a flowchart showing the actual measurement time calculation procedure according to the present embodiment. This series of processing is performed by the ECU 90.

[0081] The processing of S221 to S223 is the same as the processing of S121 to S123 in Fig. 6.

[0082] At S224, it is determined whether the estimate f is equal to "1" or not (S224). In this determination, if it is determined that the estimate f is not equal to "1" (S224: NO), the process restarts from the processing at S222. On the other hand, in this determination, if it is determined that the estimate f is equal to "1" (S224: YES), the actual measurement f, which indicates whether the calculation of the actual measurement time has been completed, is set to "0". That is, since the calculation of the counter cnt2 (actual measurement time) has not been completed, the actual measurement time f is set to "0". After that, this series of processing ends (END).

[0083] Furthermore, in the determination at S222, if it is determined that the detection pressure Pm is not equal to or higher than the final pressure FP2 (S222: NO), the actual measurement f is set to "1" (S226). After that, this series of processing is terminated (END).

[0084] With reference to Fig. 9, it is determined at S23 whether estimate f = 1 and actual measurement f = 0 (S23). If this determination is negative (S23: NO), the process proceeds to processing at S24. The processing at S24 to S26 is the same as that at S14 to S16 in Fig. 3.

[0085] On the other hand, in the determination at S23, in the case of determining that estimation f = 1 and actual measurement f = 0 (S23: YES), and in the case of determining at S24 that the value obtained by subtracting counter cnt2 from counter cnt1 is not greater than the determination value (S24: NO), the valve opening f indicating whether or not the relief valve 80 is in the open state is set to "0." Thereafter, this series of processing is ended (END). Note that the processing at S21 corresponds to the processing as the estimation unit. The processing at S23 to S26 corresponds to the processing as the determination unit.

[0086] Fig. Fig. 13 is a time chart showing the operation example corresponding to the relief valve determination according to the present embodiment. Here, the operation example is shown at time t41 corresponding to time t24 in Fig.8 and the subsequent period.

[0087] At time t41, when the detection pressure Pm drops below the start pressure FP1, the execution condition is met. Accordingly, the calculation of counter cnt1 (estimation time) and counter cnt2 (actual measurement time) is started, and the incrementation of counters cnt1 and cnt2 is started.

[0088] At time t42, when the detection pressure Pm is lower than the final pressure FP2, the incrementation of the counter cnt2 stops, and the actual measurement f becomes "1." Subsequently, the counter cnt1 is set to a value obtained by adding the counter est to the counter cnt1. Furthermore, it is determined that the value obtained by subtracting the counter cnt2 from the counter cnt1 is greater than the determination value, and the valve opening f becomes "1." With this configuration, it is determined that the relief valve 80 is in the open state. Note that the estimate f is still equal to "0."

[0089] The present embodiment, as described in detail above, has the following advantages. Only the advantages that differ from the first embodiment will be described here.

[0090] - The ECU 90 determines whether the relief valve 80 is in the open state when the estimated pressure Pe and / or the detection pressure Pm drops to the final pressure FP2 set lower than the start pressure FP1. If the detection pressure Pm drops to the final pressure FP2 before the estimated pressure Pe, it is determined that the relief valve 80 is in the open state. Accordingly, it is possible to determine whether the relief valve 80 is in the open state when the estimated pressure Pe and / or the detection pressure Pm drops to the final pressure FP2. If it is determined that the relief valve 80 is in the open state, it is possible to perform fail-safe processing or the like at an early stage.

[0091] - When the detection pressure Pm drops to the final pressure FP2 before the estimated pressure Pe, the time period in which the estimated pressure Pe drops from the start pressure FP1 to the final pressure FP2 is estimated, and it is determined whether the relief valve 80 is in the open state or not. Accordingly, by determining that the relief valve 80 is in the open state, it is possible to perform fail-safe processing or the like at an early stage.

[0092] Note that the above-described embodiments can be modified and implemented as follows. Elements similar to those in the above-described embodiments are denoted by the same reference numerals, and explanations of the elements are omitted.

[0093] - There may be a configuration that when the determination pressure Pm first drops from the start pressure FP1 to the end pressure FP2, the ECU 90 (corresponding to the determination unit) determines that the relief valve 80 is in the open state, and when the estimated pressure Pe first drops, it is determined that the relief valve 80 is in the closed state.

[0094] - The pressure FP0, the start pressure FP1 and the end pressure FP2 can be set according to the machine speed of the machine 10.

[0095] - It is also possible to control the rate of decrease of the estimated pressure Pe by correcting at least one of the injection quantity q, the volume V and the elastic modulus K instead of using the parameter A.

[0096] - It is also possible to return the fuel from the supply line 60 to the pipe 22 or the fuel tank 18 using the pressure relief valve 80.

[0097] - It is also possible to use an electrically driven high-pressure pump driven by a rotating electric machine as the high-pressure pump 30.

[0098] - It is also possible to use not only a direct fuel injection engine using gasoline as fuel, but also a direct fuel injection engine using ethanol or the like as fuel, a diesel engine with a common rail, as the engine 10.

[0099] The present disclosure has been described according to the embodiments, but it should be understood that the present disclosure is not limited to the embodiments and structures. The present invention encompasses various modifications within the scope described in the claims. Furthermore, various combinations and forms, as well as further combinations and forms including only one element or more or less, are included within the scope and spirit of the present invention.

Claims

[1] A pressure relief valve determining device (90) configured to determine that a pressure relief valve in a high-pressure fuel supply system is in an open state, the high-pressure fuel supply system comprising: a fuel injection valve (62) configured to inject fuel; a high pressure pump (30) configured to compress the fuel and deliver the fuel to a supply path (44) directed toward the fuel injection valve; a pressure sensor (82) configured to detect a fuel pressure on a pressure side of the high-pressure pump; and the pressure relief valve (80) configured to enter an open state when the fuel pressure on the pressure side is higher than a valve opening pressure to reduce the fuel pressure on the pressure side to a predetermined pressure, wherein the pressure relief valve determining device comprises: an estimation unit configured to estimate the fuel pressure on the pressure side based on an amount of fuel injection with the fuel injection valve from a time point at which the fuel pressure detected with the pressure sensor changes from a higher state than a first pressure set lower than the valve opening pressure to a lower state, assuming that the fuel is not discharged with the high-pressure pump; and a determination unit configured to determine that the relief valve is in the open state based on a decrease mode of the fuel pressure estimated by the estimation unit and a decrease mode of the fuel pressure detected by the pressure sensor. [2] The relief valve determining device according to claim 1, wherein the determining unit is configured to determine whether or not the relief valve is in the open state when at least one of the fuel pressure estimated by the estimating unit and the fuel pressure detected by the pressure sensor decreases to a second pressure set lower than the first pressure. [3] The pressure relief valve determining device according to claim 2, wherein the determining unit is configured such that based on a period of time in which the fuel pressure estimated by the estimation unit decreases from the first pressure to the second pressure and a period of time in which the fuel pressure detected by the pressure sensor decreases from the first pressure to the second pressure, determines whether the pressure relief valve is in the open state or not, and estimates a period of time in which the fuel pressure estimated by the estimation unit decreases from the first pressure to the second pressure when the fuel pressure detected by the pressure sensor decreases to the second pressure before the fuel pressure estimated by the estimation unit. [4] The relief valve determining device according to any one of claims 1 to 3, wherein the estimating unit is configured to estimate the fuel pressure on the pressure side to decrease faster than an actual fuel pressure on the pressure side when the relief valve is in a closed state and when the fuel is not discharged with the high-pressure pump, even if the actual fuel pressure on the pressure side varies. [5] Pressure relief valve determining device according to claim 1 or 2, wherein the estimation unit is configured to estimate the fuel pressure on the pressure side so that it decreases faster than the actual fuel pressure on the pressure side when the relief valve is in a closed state and when the fuel is not discharged by the high-pressure pump, even if the actual fuel pressure on the pressure side varies, and the determination unit is configured to determine that the pressure relief valve is in the open state when a period of time in which the fuel pressure detected by the pressure sensor decreases from the first pressure to a second pressure set lower than the first pressure is shorter than a period of time in which the fuel pressure estimated by the estimation unit decreases from the first pressure to the second pressure. [6] The relief valve determining device according to any one of claims 1 to 5, wherein the estimation unit is configured to estimate the fuel pressure on the pressure side based on the amount of fuel injection with the fuel injection valve, a bulk modulus of the fuel, and a fuel temperature.

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