초록 ▼

A control unit for controlling fuel pressure in a common rail comprises a pressure sensor for detecting fuel pressure in the common rail, a decreased amount presuming means for calculating a presumed decreased amount (PC1) of the common rail fuel pressure, and a first determination means for compari

A control unit for controlling fuel pressure in a common rail comprises a pressure sensor for detecting fuel pressure in the common rail, a decreased amount presuming means for calculating a presumed decreased amount (PC1) of the common rail fuel pressure, and a first determination means for comparing the detected decreased amount (PC2) of the common rail fuel pressure with the presumed decreased amount (PC1), in order to determine whether any abnormal condition is in the outputs from the pressure sensor. Therefore, the malfunction of the pressure sensor or any abnormal conditions included in the outputs from the pressure sensor can be detected even during the engine operation.

대표청구항 ▼

What is claimed is: 1. A common rail fuel injection system for an internal combustion engine comprising: a high pressure pump for discharging high pressure fuel; a common rail for accumulating the high pressure fuel supplied from the high pressure pump; multiple injectors for injecting the high pr

What is claimed is: 1. A common rail fuel injection system for an internal combustion engine comprising: a high pressure pump for discharging high pressure fuel; a common rail for accumulating the high pressure fuel supplied from the high pressure pump; multiple injectors for injecting the high pressure fuel from the common rail into respective cylinders of the engine; a pressure sensor for detecting common rail fuel pressure of the high pressure fuel accumulated in the common rail; and a control unit for controlling a discharge amount of the high pressure fuel to be discharged from the high pressure pump in order that a detected fuel pressure (PCi) detected by the pressure sensor will coincide with a target fuel pressure (PC0) calculated in accordance with operational conditions of the engine, and for controlling a fuel injection amount to be injected by the injector in order that an injected fuel amount will coincide with a target fuel injection amount calculated in accordance with the operational conditions of the engine, wherein the control unit comprises; a decreased amount presuming means for calculating a presumed decreased amount (PC1) of the common rail fuel pressure, which occurs as a result of the fuel injection by the injectors; a first determination means for directly or indirectly comparing a detected decreased amount (PC2) of the common rail fuel pressure detected by the pressure sensor with the presumed decreased amount (PC1), and for determining whether an abnormal condition is included in the outputs from the pressure sensor. 2. A common rail fuel injection system according to claim 1, wherein the first determination means determines an abnormal condition of "shortage of fuel injection", in the case that the detected decreased amount (PC2) is smaller than a predetermined normal range of the presumed decreased amount (PC1), and the first determination means determines an abnormal condition of "excess of fuel injection", in the case that the detected decreased amount (PC2) is larger than the predetermined normal range of the presumed decreased amount (PC1). 3. A common rail fuel injection system according to claim 1, further comprising: a combustion result detecting sensor for detecting combustion result in the engine by the fuel injection from the injectors, wherein the control unit further comprises; a combustion result presuming means for calculating a presumed value representing combustion result, based on the fuel injection amount from the injectors; a second determination means for directly or indirectly comparing a detected value representing the combustion result detected by the combustion result detecting sensor with the presumed value calculated by the combustion result presuming means, and for determining whether an abnormal condition occurs in the fuel injection amount; and a total determination means for identifying a portion in which the abnormal condition occurs, based on the determinations of the first and second determination means. 4. A common rail fuel injection system according to claim 1, further comprising: an exhaust gas temperature sensor for detecting exhaust gas temperature (TGi) of the exhaust gas emitted from the engine, wherein the control unit further comprises; a combustion result presuming means for calculating a presumed exhaust gas temperature (TG1), based on the fuel injection amount from the injectors; a second determination means for directly or indirectly comparing the detected exhaust gas temperature (TGi) with the presumed exhaust gas temperature (TG1), and for determining whether an abnormal condition occurs in the fuel injection amount; and a total determination means for identifying a portion in which the abnormal condition occurs, based on the determinations of the first and second determination means. 5. A common rail fuel injection system according to claim 4, wherein the second determination means determines an abnormal condition of "excess of fuel injection", in the case that the detected exhaust gas temperature (TGi) is higher than a predetermined normal range of the presumed exhaust gas temperature (TG1). 6. A common rail fuel injection system according to claim 4, wherein the second determination means determines that the fuel injection amount is in a normal condition, in the case that the detected exhaust gas temperature (TGi) is within the predetermined normal range of the presumed exhaust gas temperature (TG1), and the total determination means determines that a fuel leakage has occurred at portions other than the inside of the respective engine cylinders, in the case that first determination means determines the abnormal condition of "excess of fuel injection", whereas the second determination means determines the normal condition in the fuel injection amount. 7. A common rail fuel injection system according to claim 1, wherein the control unit further comprises; a drive means for driving a warning device to indicate to a vehicle driver the abnormal condition in the fuel injection amount, based on the determination at the first determination means. 8. A common rail fuel injection system according to claim 5, wherein the control unit further comprises; a drive means for applying a further limit to an upper limit of fuel injection amount, in the case that the first and second determination means determine the abnormal condition of "excess of fuel injection". 9. A common rail fuel injection system according to claim 6, wherein the control unit further comprises; a drive means for stopping the operation of the engine, in the case that the total determination means determines that the fuel leakage has occurred at portions other than the inside of the respective engine cylinders.