Method and device for preventing a vehicle engine from stalling

Abstract

Method for preventing a vehicle engine from stalling, comprising a fuel injection device (2) for pressurizing fuel stored in a fuel tank (20) by means of a high-pressure fuel pump (50) to supply the fuel to a common fuel line (2c) and injecting the fuel temporarily stored in the common fuel line (2c) into an engine via an injection valve (2e, 70), comprising the following steps: determining whether a predetermined time has elapsed after starting the engine when it is determined that the vehicle is idling; performing fuel pressure control when it is determined that the predetermined time has elapsed after starting the engine; determining whether or not drift occurs in an output signal of a high-pressure fuel pressure sensor (61) for measuring the fuel pressure on the downstream side of the high-pressure fuel pump (50);and performing fuel pressure control by replacing a high-pressure fuel pressure value with a predetermined pressure value based on the output signal of the high-pressure fuel pressure sensor (61).;

Description

TECHNICAL FIELDThe present disclosure relates to a method and an apparatus for preventing stalling of a vehicle engine, and more particularly, to a method and an apparatus capable of preventing stalling of a vehicle engine when a drift has occurred in an output signal of a high-pressure fuel pressure sensor.BACKGROUNDA fuel supply system of an engine, in particular a fuel supply system of a direct injection gasoline engine, may be divided into a high pressure system and a low pressure system. Like a fuel injection device 2 shown in FIG. 1, the high pressure system may include a high pressure pump 2 afor recompressing the fuel pumped from a fuel tank by a low pressure fuel pump at high pressure, a fuel filter 2 bfor filtering the fuel pumped from the high pressure pump 2 a, a common fuel line (common rail) 2 cfor maintaining the pressure of the high pressure fuel filtered by the fuel filter 2 bas it is and distributing it into a single injection valve 2 evia a high pressure fuel line 2 d, an injection valve 2 efor injecting the fuel supplied via the high pressure fuel line 2 dinto a combustion chamber of an engine 6, a high pressure fuel pressure sensor (not shown), etc. On the other hand, the low pressure system may include a low pressure pump, a low pressure fuel pressure sensor, etc., which may direct fuel stored in the fuel tank into the high pressure system.Meanwhile, the amount of fuel supplied into the cylinder of the engine is determined by the pressure value of the high-pressure fuel in the common rail 2 cand the electric pulse time used for the injection valve 2 e. Accordingly, an engine control apparatus 1 first obtains a required fuel injection amount and a target high-pressure fuel pressure corresponding to the fuel injection amount to obtain a target output torque. Then, the engine control device 1 measures the fuel pressure on the downstream side of the high pressure pump 2 a, obtains a control operation value of an engine actuator of the high pressure pump 2 ausing the measured fuel pressure and the target fuel pressure, and controls an engine 41 depending on the obtained control operation value.Accordingly, it is important to accurately measure the actual high-pressure fuel pressure value in order to supply an exact fuel injection amount to the engine. When the measured pressure value is excessively higher or lower than the actual fuel pressure, the fuel injection amount is also calculated inaccurately and no adequate fuel is supplied. Consequently, a problem of engine stalling may occur.Meanwhile, unstable sensitivity change or output level due to time, temperature or for some reason is referred to as instability of the sensor characteristic or drift. When the drift occurs in an output signal of the high-pressure fuel pressure sensor for measuring the high-pressure fuel pressure, as shown in FIG. 5A, the fuel pressure immediately rises or falls.Accordingly, when the fuel amount control is executed using the sensor signal in which the drift has occurred, the fuel amount is erroneously calculated based on the erroneous fuel pressure. That is, there occurs a problem in that the fuel is injected promptly and excessively lean or rich, and thereby, as shown in FIG. 5A, the engine speed becomes unstable, thereby causing the engine stall phenomenon.The contents described in the background are for understanding the background of the present disclosure, and may include things not known to those skilled in the art to which the present disclosure pertains.WO 2009 / 141 199 A1 describes a method for detecting a malfunction and, in particular, a drift of a rail pressure sensor in a common rail injection system. A method is proposed for diagnosing the rail pressure sensor in the event of start problems.US 2003 / 0 010 319 A1 describes a fuel injection apparatus in which a plurality of high pressure fuel supply parts each comprising a feed pump part and a fuel metering part are arranged in parallel between a feed pump part sucking fuel from a fuel tank and a common fuel line, so that injection of a certain amount of fuel can be maintained even when a high pressure pump fails, and even when a high pressure fuel supply part fails, a common rail pressure can be maintained by the other high pressure fuel supply component.DE 10 2013 106 712 A1 describes a fuel pump control device. When a rail pressure sensor is in a normal state, the fuel injection control device controls a control valve based on a pressure in the common rail. When the rail pressure sensor is in an abnormal state, the fuel injection control device controls the control valve based on an estimated pump discharge amount.ILLUSTRATIONThe present disclosure is intended to solve the above-described related art problem, and an object of the present disclosure is to provide a method for preventing a stall of a vehicle engine and an apparatus for preventing a stall of a vehicle engine, which can solve the engine stall problem caused by occurrence of drift in an output signal of a high-pressure fuel pressure sensor. The method according to the present invention is defined in independent claims 1 and 2. The device according to the present invention is defined in independent claims 6 and 7. Preferred embodiments are given in the dependent claims.The present disclosure compares the target pressure with the high pressure fuel pressure measured by the high pressure fuel pressure sensor to determine whether or not a signal drift occurs. In addition, when it is determined that the drift has occurred in the output signal, the present disclosure performs pressure control by using not the output value of the high-pressure fuel pressure sensor but a predetermined pressure value or a low-pressure fuel pressure on the upstream side of the high-pressure fuel pump, thereby suppressing stalling of the engine due to the signal drift.More specifically, the present disclosure is directed to a method for preventing a stall of a vehicle engine having a fuel injection device for pressurizing fuel stored in a fuel tank by a high pressure fuel pump to direct the fuel into a common fuel line, and injecting the fuel temporarily stored in the common fuel line into an engine via an injection valve. The method may include steps of determining whether or not a drift occurs in an output signal of a high-pressure fuel pressure sensor for measuring the fuel pressure on a downstream side of the high-pressure fuel pump; and executing fuel pressure control by replacing a high-pressure fuel pressure value with a predetermined pressure value based on the output signal of the high-pressure fuel pressure sensor.A method for preventing a stall of a vehicle engine according to another preferred embodiment of the present disclosure for solving the above problem may include steps of performing fuel pressure control by not using an output signal of a high-pressure fuel pressure sensor but performing low-pressure control based on the low-pressure fuel pressure on an upstream side of the high-pressure fuel pump when it is determined that a drift has occurred in the output signal of the high-pressure fuel pressure sensor for measuring the fuel pressure on an downstream side of the high-pressure fuel pump.More preferably, the vehicle engine stall prevention method may include executing the fuel pressure control by replacing the high pressure fuel pressure value with the predetermined pressure value based on the output signal of the high pressure fuel pressure sensor, and then executing the fuel pressure control by means of a low pressure control based on a low pressure fuel pressure on the upstream side of the high pressure fuel pump.More preferably, the method for preventing the stall of a vehicle engine may further comprise determining whether or not a vehicle is now idling, and when the vehicle is idling, the fuel pressure control is executed.More preferably, the predetermined pressure value is determined from a predetermined map with respect to the fuel pressure value depending on the running state of the vehicle.More preferably, the step of determining whether or not the drift occurs in the output signal of the high-pressure fuel pressure sensor may include determining whether or not a pressure difference between a target fuel pressure and an actual fuel pressure measured by the high-pressure fuel pressure sensor is equal to or greater than a predetermined value; incrementing a counter when the pressure difference is equal to or greater than a predetermined value; and determining that the drift has occurred in the output signal of the high-pressure fuel pressure sensor when the counter is equal to or greater than a predetermined value.According to the present invention, the method for preventing the engine from stalling further includes determining whether or not a predetermined time has elapsed after cranking and executing the fuel pressure control when it is determined that the predetermined time has elapsed after cranking.An engine stall prevention apparatus according to the present disclosure for solving the above problem may include a fuel injection device for pressurizing fuel stored in a fuel tank by a high-pressure fuel pump to supply the fuel to a common fuel line and injecting the fuel temporarily stored in the common fuel line into an engine via an injection valve; a high-pressure fuel pressure sensor for measuring high-pressure fuel pressure on a downstream side of the high-pressure fuel pump; and an engine controller for determining whether or not a drift occurs in an output signal of a high-pressure fuel pressure sensor, and upon occurrence of the drift, performing fuel pressure control by replacing a high-pressure fuel pressure value with a predetermined pressure value based on the output signal of the high-pressure fuel pressure sensor.An engine stall prevention apparatus according to another embodiment of the present disclosure for solving the above problem may include a fuel injection device for pressurizing fuel stored in a fuel tank by a high-pressure fuel pump to supply the fuel to a common fuel line and injecting the fuel temporarily stored in the common fuel line into an engine via an injection valve; a high-pressure fuel pressure sensor for measuring high-pressure fuel pressure on a downstream side of the high-pressure fuel pump; and an engine control apparatus for determining whether or not a drift occurs in an output signal of a high-pressure fuel pressure sensor, and when the drift occurs, performing fuel pressure control by not using the output signal of the high-pressure fuel pressure sensor but performing low-pressure control based on the low-pressure fuel pressure on a upstream side of the high-pressure fuel pump.Preferably, the engine control device executes the fuel pressure control by replacing the high-pressure fuel pressure value based on the output signal of the high-pressure fuel pressure sensor with the predetermined pressure value, and then executes the fuel pressure control by means of a low-pressure control based on the low-pressure fuel pressure on the upstream side of the high-pressure fuel pump.Preferably, the engine control unit executes the fuel pressure control when the vehicle is idling.Preferably, the engine control device includes a predetermined map related to the fuel pressure value depending on a running state of the vehicle, and the predetermined pressure value is determined using the predetermined map.According to an aspect of the present disclosure, an engine control device may execute pressure control by not using an output value of a high-pressure fuel pressure sensor but using a predetermined pressure value or a low-pressure fuel pressure on an upstream side of a high-pressure fuel pump when a drift has occurred in the output signal of the high-pressure fuel pressure sensor. Thus, stall of the engine due to signal drift can be effectively suppressed, and vehicle stability can be secured.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a diagram showing a configuration of a high pressure system of a fuel supply system of a direct injection engine of a fuel supply system of a fuel injection system of a fuel injection engine. FIG. 2 is a block diagram showing a configuration of an engine stall prevention apparatus according to a preferred embodiment of the present disclosure. FIG. 3 is a flow chart illustrating a method for preventing engine stall according to a preferred embodiment of the present disclosure. FIG. 4 is a flow chart showing a method for preventing engine stall according to another preferred embodiment of the present disclosure. FIG. 5A is a graph showing the occurrence of drift in a pressure sensor output signal and the change in engine speed at the time in fuel pressure control according to the conventional control method. FIG. 5B is a graph showing the occurrence of drift in a pressure sensor output signal and the change in engine speed at the time when the method for preventing stall of an engine according to the present disclosure is applied.DETAILED DESCRIPTIONHereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.FIG. 2 is a block diagram showing a configuration of an engine stall prevention apparatus according to a preferred embodiment of the present disclosure.An engine stall prevention apparatus according to the present disclosure is configured to include: a fuel injection device including a high pressure fuel pump 50, a common rail 60, and an injection valve 70; an engine control device 10 for controlling the fuel injection device to prevent an engine stall; a high pressure fuel pressure sensor 61 for measuring high pressure fuel pressure on the downstream side of the high pressure fuel pump 50 and / or a low pressure fuel pressure sensor 40 for measuring low pressure fuel pressure on the upstream side of the high pressure fuel pump 50.First, with reference to FIG. 2, a fuel supply system of an engine to which the engine stall prevention apparatus according to the present disclosure may be applied will be described.The intended fuel is stored in a fuel tank 20, and the fuel stored in the fuel tank 20 is pumped at a predetermined low pressure by a low-pressure fuel pump 30 to be supplied to the high-pressure system including the high-pressure fuel pump. The motor controller 1 determines a control operation value of a motor actuator (brushless DC motor) 31 using a target low-pressure pressure value and the fuel pressure value measured by the low-pressure fuel pressure sensor 40 on the downstream side of a low-pressure fuel pump 30, and controls the motor actuator depending on the control operation value so that the fuel discharged from the low-pressure fuel pump 30 can reach a predetermined low pressure.The low-pressure fuel discharged from the low-pressure fuel pump 30 is compressed to a higher pressure by the high-pressure fuel pump 50. The high pressure compressed fuel is temporarily stored in the common rail 60, and is supplied to the injector 70 of a plurality of cylinders via a high pressure fuel rail (not shown) to be injected into the plurality of cylinders of the engine.The supply amount of the fuel supplied to the cylinders is determined depending on the pressure value of the high-pressure fuel and the electric pulse time of the signal for the control of the injection valve, as described above. Accordingly, the engine control device 10 acquires the required fuel injection amount and the target high-pressure fuel pressure corresponding to the required fuel injection amount to obtain a target output torque, then the engine control device 10 measures the fuel pressure on the downstream side of the high-pressure fuel pump 50 by means of the high-pressure fuel pressure sensor 61, and then determines a control operation value of an engine actuator 51 of the high-pressure fuel pump 50 so that the measured high-pressure fuel pressure follows the target pressure, and controls the engine actuator 51 of the high-pressure fuel pump 50 depending on the acquired control operation value.The high-pressure fuel pressure sensor 61 is preferably installed in the common rail 60, as shown in FIG. 3, to measure the pressure of the fuel stored in the common rail 60, to measure the high-pressure fuel pressure on the downstream side of the high-pressure fuel pump 50. However, as shown in FIGS. 5A and 5B, there may occur the phenomenon that the output level of the high-pressure fuel pressure sensor 61 rapidly rises or falls due to time, temperature, or for some reason, regardless of the actual fuel pressure value.When the fuel pressure control is continuously executed using the output value of the high-pressure fuel pressure sensor 61, even if a drift has occurred in the output signal of the high-pressure fuel pressure sensor 61, a problem occurs in that the fuel injection amount based on the measured fuel pressure becomes excessively large (rich) or excessively small (lean) as compared with the preferred fuel injection amount depending on the required power. Consequently, the engine speed becomes unstable, causing the problem of engine stalling. Particularly, in the idling range in which the engine speed is low, the possibility that stall of the engine occurs upon occurrence of drift in the fuel pressure sensor signal rapidly becomes high.In order to solve the above problem, the engine control apparatus 10 according to an aspect of the present disclosure appropriately executes the pressure control by not using the output value of the high-pressure fuel pressure sensor 61 when a drift occurs in the fuel pressure sensor signal.For this purpose, the engine control device 10 first determines whether or not a drift has occurred. Here, whether or not a drift has occurred can be detected by comparing the measured fuel pressure with the target pressure value. For example, when the difference between the target fuel pressure value and the high-pressure fuel pressure value measured by the high-pressure fuel pressure sensor 61 exceeds a predetermined reference value, there is the reasonable expectation that drift has occurred. However, the rapid change of the measured pressure value may not be caused by the drift phenomenon of the pressure sensor, but may be a transient phenomenon due to a momentary physical abnormality or noise of the fuel supply apparatus or other causes. Accordingly, in the preferred embodiment of the present disclosure, in order to further clarify whether or not a drift has occurred in a signal, the timer is increased when the difference between the target pressure value and the measured fuel pressure exceeds the reference value. Then, when the timer exceeds a predetermined value, that is, the phenomenon that the difference between the target pressure value and the measured fuel pressure exceeds the reference value repeats by a predetermined reference value or more, it is determined that the drift has occurred.Meanwhile, when it is determined that the drift has occurred in the output signal of the high-pressure fuel pressure sensor 61, the preferred embodiment of the present disclosure performs low-pressure control that does not perform the pressure control based on the high pressure on the downstream side of the high-pressure fuel pump 50, but only the pressure control based on the low pressure on the upstream side of the high-pressure fuel pump 50. The low-pressure control is executed by controlling the engine actuator 31 of the low-pressure fuel pump 30 or adjusting the opening of a low-pressure fuel valve (not shown) installed in a fuel line between the low-pressure fuel pump 30 and the high-pressure fuel pump 50. The engine speed is relatively low at 500~600 U / min, and the change in the fuel injection amount or the fuel pressure is not large during idling of a vehicle, while as described above, there is the characteristic liable to a problem of stalling of the engine. Accordingly, it is necessary to execute control that weights more on preventing engine stall than precise fuel pressure control during idling. Accordingly, the present disclosure does not execute the high-pressure control based on the high pressure on the downstream side of the high-pressure fuel pump 50, but executes the low-pressure control based on the low pressure on the upstream side of the high-pressure fuel pump 50, thereby preventing the engine from stalling.By means of the low pressure control described above, it is possible to somewhat suppress stalling of the engine due to the output signal drift of the pressure sensor. However, the operation stably switching from the high pressure control to the low pressure control takes a certain time, and the possibility of occurrence of engine stall due to an erroneous pressure value during this time cannot be completely eliminated. Accordingly, an immediate response method is necessary to more reliably suppress stall of the engine due to the signal drift.To this end, another preferred embodiment of the present disclosure, when it is determined that the drift has occurred in the output signal of the high-pressure fuel pressure sensor 61, does not use the output value of the high-pressure fuel pressure sensor 61 but uses the pressure value determined by a predetermined map as the high pressure on the downstream side of the high-pressure fuel pump 50. For example, the high pressure fuel pressure value corresponding to the state variable of the engine, e.g., idle speed or torque, is stored in the engine control device 10 in the form of a table, and the engine control device 10 selects an appropriate high pressure fuel pressure value based on the table depending on the running state of the vehicle, and replaces the measured fuel pressure value with the selected high pressure fuel pressure value. Subsequently, the pressure control is executed by adopting the replaced high-pressure fuel pressure value as the actual high-pressure fuel pressure value, so that the pressure on the downstream side of the high-pressure fuel pump 50 becomes the target pressure value. As shown in FIG. 5B, even when the pressure value measured by the high-pressure fuel pressure sensor 61 exceeds the target pressure value by 3.5 MPa or more, it is recognized that it is possible to replace the measured pressure value with the prestored pressure value, and thus to stably maintain the engine speed. Consequently, the problem of the stall of the motor due to the occurrence of the drift can be solved.However, the pressure value prestored in the engine control device 10 is not an actual high-pressure fuel pressure value, but is only an estimated value depending on the running state. Accordingly, it is difficult to continue the fuel pressure control or the fuel injection amount control using the replaced pressure value.According to another preferred embodiment according to the present disclosure, the measured pressure value is replaced with the prestored pressure value and then shifts to the low pressure control. It is possible to replace the measured pressure value with the prestored pressure value to first provide a pre-emptive and immediate response, and then to shift to the low pressure control, thus securely preventing the possibility of engine stalling and additionally realizing somewhat stable fuel pressure control and fuel amount injection control. Preferably, it executes the high-pressure control by replacing the measured pressure value with the prestored pressure value, and can then immediately change to the low-pressure control after a predetermined time has elapsed.After changing to the low pressure control, the engine control device 10 maintains the low pressure control state during the corresponding drive cycle as it is until the driver turns off the ignition. After restarting by the driver, it is then determined whether or not the drift has occurred, and when it is determined that the drift has not occurred, the low pressure control is canceled and the normal high pressure control is executed again.FIG. 3 is a flow chart illustrating a method for preventing engine stalling according to a preferred embodiment of the present disclosure. The control method shown in FIG. 3 is the embodiment related to a control method for preventing the engine from stalling by performing low pressure control upon occurrence of signal drift.As shown in FIG. 3, the engine control apparatus 10 first determines whether or not the vehicle is now idling S 10. As described above, the engine speed at idling is relatively low at about 500~600 U / min, and there is an extremely high possibility that the problem of stalling of an engine due to the signal drift occurs. On the other hand, when switching from the existing high pressure control to the low pressure control to the engine stall prevention control, it is difficult to accurately execute the fuel pressure control and the fuel injection amount control to achieve the required torque. Accordingly, the engine stall prevention control is executed only at idle, and it is first determined whether it is at idle or not to maintain the high pressure control in the remaining running state as it is S90.When it is determined that it is idling, the engine control device 10 determines whether or not a certain time has elapsed after cranking S 20. Since the fuel pressure is not stabilized until the predetermined time has elapsed after the cranking, it is difficult to determine whether or not the signal drift has occurred based on the difference between the fuel pressure and the target pressure. Accordingly, by first determining whether or not the predetermined time has elapsed after the cranking, determining whether or not the signal drift has occurred only after the lapse of the predetermined time, control is executed depending on the above, and the high pressure control is maintained as it is within the predetermined time after the cranking S 90.When it is determined that the running state of the vehicle is idling and the predetermined time has elapsed after the cranking, the engine controller 10 measures the fuel pressure of the high-pressure fuel on the downstream side of the high-pressure fuel pump 50 using the high-pressure fuel pressure sensor 61 to determine whether or not the signal drift has occurred S 30. When the drift occurs in the pressure signal, the signal level of the high-pressure fuel pressure sensor 61 changes immediately and quickly, and accordingly, there occurs a case that the pressure value of the measured high-pressure fuel exceeds the target fuel pressure value for achieving the required torque. Accordingly, in order to determine whether or not the drift has occurred, the engine control device 10 first determines whether or not the difference of the high-pressure fuel pressure value measured by the high-pressure fuel pressure sensor 61 has exceeded a predetermined reference value S 40.When the measured pressure value exceeds the target pressure value by the reference value or more, there is the established suspected that the drift has occurred. Now, in order to confirm whether or not the signal drift has occurred, it is necessary to determine whether or not the phenomenon that the measured pressure value repeatedly exceeds the target pressure value by the reference value or more repeatedly occurs. To do so, the engine control device 10 increases the timer by 1 when the measured pressure value exceeds the target pressure value by the reference value or more S 50. When the timer exceeds the predetermined reference value as an increased result, that is, the phenomenon that the difference between the target pressure value and the measured fuel pressure exceeds the reference value repeats by the predetermined reference value or more, it is determined that the drift has occurred S 60. The timer is reset to zero when the driver turns off the ignition, and is added again in the next drive cycle.As the measurement result of the high-pressure fuel pressure sensor 61, when it is determined that the drift has occurred in the pressure sensor signal, the low-pressure control is executed that does not execute the pressure control based on the high pressure on the downstream side of the high-pressure fuel pump 50, but only the pressure control based on the low pressure on the upstream side of the high-pressure fuel pump 50 S 70. That is, control is executed so that the value measured by the low-pressure fuel pressure sensor 40 follows the target low pressure. Consequently, it is possible to block the influence of the signal drift of the high-pressure fuel pressure sensor 61 and thus prevent the engine from stalling.The low pressure control in S 70 is continued until the driver turns off the ignition S 80. Upon restarting by the driver, it is again determined whether or not the drift has occurred, and when it is determined that the drift has not occurred, the low pressure control is canceled and the normal high pressure control is executed again.FIG. 4 is a flow chart showing a method for preventing engine stall according to another preferred embodiment of the present disclosure. Unlike the control method shown in FIG. 3, the control method shown in FIG. 4 does not execute the low pressure control when the signal drift has occurred, but executes the high pressure control by replacing a high pressure fuel pressure value with a predetermined pressure value, thus preventing the engine from stalling. Detailed description of the steps substantially identical to those shown in FIG. 3 will be omitted.As shown in FIG. 4, in S 150, when it is determined that a drift has occurred in the pressure sensor signal, the engine control device 10 does not use the output value of the high-pressure fuel pressure sensor 61 but uses the pressure value determined by a predetermined map as the high pressure on the downstream side of the high-pressure fuel pump 50. for example, an appropriate high-pressure fuel pressure value depending on the current running state of the vehicle is selected from a table including the high-pressure fuel pressure value corresponding to the state variable of the engine, e.g., idling speed or torque, and the measured fuel pressure value is replaced with the high-pressure fuel pressure value. Subsequently, the high pressure control is executed by adopting the replaced high pressure fuel pressure value as the actual high pressure fuel pressure value, so that the high pressure fuel pressure on the downstream side of the high pressure fuel pump 50 becomes the target pressure value S 160. Consequently, as in the low pressure control shown in FIG. 3, it is possible to block the influence of the signal drift of the high pressure fuel pressure sensor 61 and thus prevent the engine from stalling.Preferably, the engine control device 10 determines whether or not a predetermined time has elapsed after the pressure value of the high-pressure fuel is replaced S 170. When it is determined that the drift has occurred in the pressure sensor signal, the possibility that engine stall occurs immediately becomes very high, so that it is first necessary to replace the pressure value of the high-pressure fuel with the stable target value. However, since the replaced pressure value does not represent the actual fuel pressure value, accurate fuel pressure control or fuel injection control for achieving the required torque is difficult. Accordingly, when it is determined that the predetermined time has elapsed, the high pressure control is switched to the low pressure control based on the pressure on the downstream side of the high pressure fuel pump 50, as shown in FIG. 3, S 180.FIG. 5A shows the change in the engine speed when a drift occurs in the high pressure sensor signal using the conventional control method. According to the contents shown in FIG. 5A, the pressure value of the high-pressure fuel measured at a certain time exceeds the target pressure value by 3.5 MPa. Consequently, it can be seen that a drift occurs in the pressure sensor signal at this time. Meanwhile, according to the contents shown in FIG. 5A, it can be seen that the engine speed becomes rapidly unstable immediately after the occurrence of the drift. That is, as a result of the rapid change in the fuel pressure value of the high-pressure fuel, the amount of fuel supplied to the engine based on the pressure value of the high-pressure fuel also changes, and the engine drive thus becomes unstable. As a result, engine stall has occurred.FIG. 5B shows the change in engine speed when a drift occurs in the high pressure sensor signal when the method for preventing an engine stall according to the present disclosure is applied. As in the case shown in FIG. 5A, it can be seen that the pressure value of the high-pressure fuel measured at a certain time exceeds the target pressure value by 3.5 MPa, so that a drift occurs in the signal. Unlike the result in FIG. 5A where the high pressure sensor signal in which the drift has occurred is used as it is, the embodiment shown in FIG. 5B has replaced the measured high pressure fuel pressure value with a predetermined pressure value. As a result, it can be seen that the high-pressure fuel pressure value on which the pressure control is based is kept constant to stably maintain the engine rotational speed, and thus no problem of engine stalling is caused.

Claims

A method for preventing a vehicle engine from stalling with a fuel injection device (2) for pressurizing a fuel stored in a fuel tank (20) by means of a high pressure fuel pump (50) to supply the fuel to a common fuel line (2c), and injecting the fuel temporarily stored in the common fuel line (2c) into an engine via an injection valve (2e, 70), comprising the steps of: determining whether or not a predetermined time has elapsed after cranking when it is determined that the vehicle is idling; executing the fuel pressure control when it is determined that the predetermined time has elapsed after cranking; determining whether or not a drift occurs in an output signal of a high pressure fuel pressure sensor (61) for measuring the fuel pressure on the downstream side of the high pressure fuel pump (50); and executing fuel pressure control by replacing a high pressure fuel pressure value with a predetermined pressure value based on the output signal of the high pressure fuel pressure sensor (61).A method for preventing a vehicle engine from stalling with a fuel injection device (2) for pressurizing a fuel stored in a fuel tank (20) by means of a high-pressure fuel pump (50) to direct the fuel into a common fuel line (2c), and injecting the fuel temporarily stored in the common fuel line (2c) into an engine via an injection valve (2e, 70), comprising the steps of: determining whether or not a predetermined time has elapsed after cranking when it is determined that the vehicle is idling; executing the fuel pressure control when it is determined that the predetermined time has elapsed after cranking; when it is determined that drift has occurred in an output signal of a high-pressure fuel pressure sensor (61) for measuring the fuel pressure on a downstream side of the high-pressure fuel pump (50), execution of fuel pressure control by low-pressure control based on the low-pressure fuel pressure on a upstream side of the high-pressure fuel pump (50) without using the output signal of the high-pressure fuel pressure sensor (61).The method for preventing stalling of the vehicle engine according to claim 1, wherein after the step of executing the fuel pressure control by replacing the high-pressure fuel pressure value based on the output signal of the high-pressure fuel pressure sensor (61) with the predetermined pressure value, the fuel pressure control is executed by means of a low-pressure control based on the low-pressure fuel pressure on an upstream side of the high-pressure fuel pump (50).The method for preventing the vehicle engine from stalling according to claim 1 or 2, further comprising determining whether or not the vehicle is now idling, wherein when it is determined that the vehicle is now idling, the fuel pressure control is executed, preferably wherein the predetermined pressure value is obtained from a predetermined map with respect to the fuel pressure value depending on the running state of the vehicle.The method for preventing stalling of the vehicle engine according to claim 1 or 2, wherein the step of determining whether or not the drift occurs in the output signal of the high-pressure fuel pressure sensor (61) comprises: determining whether or not a pressure difference between a target fuel pressure and an actual fuel pressure measured by the high-pressure fuel pressure sensor (61) is equal to or greater than a predetermined value; incrementing a counter when the pressure difference is equal to or greater than the predetermined value; and determining that the drift has occurred in the output signal of the high-pressure fuel pressure sensor (61) when the counter is equal to or greater than a predetermined value.An apparatus for preventing a stall of the vehicle engine, comprising: a fuel injection device (2) for pressurizing a fuel stored in a fuel tank (20) by means of a high pressure fuel pump (50) to direct the fuel into a common fuel line (2c) and injecting the fuel temporarily stored in the common fuel line (2c) into an engine via an injection valve (2e, 70); a high pressure fuel pressure sensor (61) for measuring the high pressure fuel pressure on a downstream side of the high pressure fuel pump (50); and an engine control device (10) configured to determine whether or not a predetermined time has elapsed after a cranking when it is determined that the vehicle is idling; execute the fuel pressure control when it is determined that the predetermined time has elapsed after the cranking; and determining whether or not a drift occurs in an output signal of the high-pressure fuel pressure sensor ( 61), and upon occurrence of the drift, performing fuel pressure control by replacing a high-pressure fuel pressure value with a predetermined pressure value based on the output signal of the high-pressure fuel pressure sensor ( 61).An apparatus for preventing a stall of the vehicle engine, comprising: a fuel injection device (2) for pressurizing a fuel stored in a fuel tank (20) by means of a high pressure fuel pump (50) to direct the fuel into a common fuel line (2c) and injecting the fuel temporarily stored in the common fuel line (2c) into an engine via an injection valve (2e, 70); a high pressure fuel pressure sensor (61) for measuring the high pressure fuel pressure on a downstream side of the high pressure fuel pump (50); and an engine control device (10) configured to determine whether or not a predetermined time has elapsed after a cranking when it is determined that the vehicle is idling; execute the fuel pressure control when it is determined that the predetermined time has elapsed after the cranking; determining whether or not a drift occurs in an output signal of the high pressure fuel pressure sensor ( 61), and upon occurrence of the drift, performing fuel pressure control by low pressure control based on the low pressure fuel pressure on an upstream side of the high pressure fuel pump ( 50) without using the output signal of the high pressure fuel pressure sensor ( 61).The vehicle engine stall prevention apparatus according to claim 6, wherein the engine control device (10) is configured to execute the fuel pressure control by replacing the high-pressure fuel pressure value with the predetermined pressure value based on the output signal of the high-pressure fuel pressure sensor (61), and then execute the fuel pressure control by means of a low-pressure control based on a low-pressure fuel pressure on an upstream side of the high-pressure fuel pump (50), wherein the engine control device (10) preferably has a predetermined map with respect to the fuel pressure value depending on the running state of the vehicle, and the predetermined pressure value is determined by means of the predetermined map.The vehicle engine stall prevention apparatus according to claim 6 or 7, wherein the engine control unit (10) is configured to execute the fuel pressure control when the vehicle is idling.

Images