JP2009209829A - Fuel supply control device and fuel supply system using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel supply control device capable of quickly decompressing common rail pressure when it determines that deceleration driving is carried out based on accelerator opening, and a fuel supply system using the same. <P>SOLUTION: When the fuel supply control device calculates the accelerator opening by time synchronization (S300), it determines whether the deceleration driving is performed or not based on the accelerator opening (S302). If the deceleration driving is performed (S302:Yes) and the deceleration status is suitable (S304:Yes), the fuel supply control device prohibits feedback control of the common rail pressure carried out by angle synchronization (S306), and calculates a quantity adjustment command value to a quantity adjustment valve for adjusting a discharge amount of a high-pressure pump based on the accelerator opening and engine rotation frequency (S308). The fuel supply control device reduces the discharge amount of the high-pressure pump by the quantity adjustment valve after calculating the accelerator opening and before the feedback control is carried out at the next timing of the angle synchronization to quickly decompress the common rail pressure (S310). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel supply control device that feedback-controls the pressure of a common rail that supplies accumulated fuel to an internal combustion engine, and a fuel supply system using the same.

Conventionally, a fuel supply system that accumulates fuel discharged from a fuel supply pump with a common rail and supplies the fuel to an internal combustion engine is known (see, for example, Patent Document 1).
In such a fuel supply system, the target common rail pressure of the common rail is calculated based on the engine operating state, and the common rail pressure is fed back based on the difference between the actual common rail pressure detected by the pressure sensor and the calculated target common rail pressure. To be controlled.

For example, if the accelerator opening decreases when the driver returns the accelerator pedal, the target common rail pressure is lower than the target common rail pressure before the accelerator opening is decreased based on the accelerator opening calculated from the output of the accelerator sensor. Is calculated. Then, the discharge amount and the like of the fuel supply pump are feedback-controlled so that the actual common rail pressure is reduced to the calculated target common rail pressure.
Japanese Patent Laid-Open No. 5-187301

  By the way, in the engine control, a time synchronization process that is repeated at predetermined time intervals and an angle synchronization process that is performed in accordance with the rotation angle of the engine are performed. Also in the angle synchronization processing, processing is performed at different angle timings according to engine control.

  The feedback control of the common rail pressure is performed at a predetermined angle synchronization timing. On the other hand, the timing for calculating the accelerator opening from the output of the accelerator sensor is mainly performed in time synchronization, and even if it is performed in the same angle synchronization, it is performed at a timing different from the angle synchronization timing of the common rail pressure.

  As described above, since the timing between the accelerator opening calculation and the feedback control is shifted, it is determined based on the deceleration operation command at the next angle synchronization timing after it is determined that the deceleration operation command is based on the calculated accelerator opening. There is a time delay until feedback control for reducing the common rail pressure is performed.

Further, the target common rail pressure for feedback control performed before the deceleration operation command is higher than the target common rail pressure for feedback control performed after the deceleration operation command.
As a result, when the common rail pressure feedback control at the angle synchronization timing before the deceleration operation command continues until the feedback control is performed at the angle synchronization timing after the deceleration operation command, the target common rail pressure calculated based on the deceleration operation command is obtained. There is a problem that the actual common rail pressure remains higher than that.

  The present invention has been made to solve the above-described problem, and a fuel supply control device capable of quickly reducing the common rail pressure when it is determined that the operation is decelerating based on the accelerator opening, and a fuel supply system using the same The purpose is to provide.

  According to the first to ninth aspects of the present invention, the feedback control means feedback-controls the common rail pressure with angle synchronization, and the accelerator opening calculation means calculates the accelerator opening with angle synchronization timing different from time synchronization or feedback control. When the deceleration determination unit determines that the deceleration operation is performed based on the accelerator opening, the feedback control prohibiting unit prohibits the feedback control by the pressure feedback control unit.

  This prevents the feedback control at the angle synchronization timing before it is determined to be the deceleration operation from continuing until the feedback control for reducing the common rail pressure is performed at the angle synchronization timing after it is determined to be the deceleration operation. . When it is determined that the vehicle is decelerating based on the calculated accelerator opening, it is possible to promptly implement appropriate control for prohibiting feedback control and reducing the common rail pressure.

According to the second aspect of the present invention, the deceleration operation determination means determines that the operation is a deceleration operation when the amount of decrease in the accelerator opening is equal to or greater than a predetermined amount.
In other words, the deceleration operation determination means does not determine that the operation is a deceleration operation when the amount of decrease in the accelerator opening is smaller than the predetermined amount. Thereby, when the amount of decrease in the accelerator opening is smaller than the predetermined amount, the feedback control is not prohibited. When the amount of decrease in the accelerator opening is smaller than the predetermined amount, the required amount of decrease in the common rail pressure is also small. Therefore, it is considered unnecessary to prohibit the feedback control and quickly decrease the common rail pressure.

  By the way, even if it is determined that the vehicle is decelerating based on the calculated accelerator opening, feedback control is performed when the actual common rail pressure does not follow the target common rail pressure and the pressure difference is large, or when the actual common rail pressure is changing rapidly. If the common rail pressure control based on the deceleration operation is prohibited, the common rail pressure may not be appropriately controlled.

  Therefore, according to the third aspect of the present invention, even if the deceleration operation determination means determines that the operation is a deceleration operation, the difference between the target common rail pressure of the common rail and the actual common rail pressure is equal to or greater than a predetermined pressure, or the actual common rail pressure If the rate of change is equal to or greater than the predetermined rate of change, the feedback control by the pressure feedback control means is permitted without being prohibited.

  Thereby, even if it is determined that the vehicle is decelerating based on the calculated accelerator opening, it is possible to prevent the feedback control from being prohibited when it is inappropriate by setting the common rail pressure condition permitting the feedback control.

  According to the fourth aspect of the present invention, in the feedback control, the amount of fuel supplied from the fuel supply pump to the common rail is measured by the metering actuator, and the metering actuator is controlled when the deceleration operation is determined. Thus, the amount of fuel supplied from the fuel supply pump to the common rail is adjusted to reduce the pressure of the common rail.

  As a result, the common rail pressure reduction control when it is determined that the vehicle is decelerating is performed by controlling the same metering actuator as when performing normal feedback control. Depressurization control is easy.

  By the way, when the amount of fuel supplied from the fuel supply pump to the common rail is measured by the metering actuator to reduce the common rail pressure when it is determined that the vehicle is decelerating, for example, the metering control is always performed so that the fuel supply amount is zero. If this is done, depending on the engine characteristics or engine operating conditions, the common rail pressure may be excessively reduced, resulting in failure to properly control the common rail pressure.

  Therefore, according to the fifth aspect of the present invention, by controlling the metering actuator, the amount of fuel supplied from the fuel supply pump to the common rail is set to a fuel amount at which the pressure of the common rail has a predetermined decompression characteristic.

  Thereby, for example, the fuel supply amount to the common rail can be variably controlled so as to have a pressure reduction characteristic set in advance based on the engine characteristic or the engine operating state. Depending on the decompression characteristics, the fuel supply amount to the common rail may become zero.

  According to the sixth aspect of the present invention, the metering control means sets the amount of fuel supplied from the fuel supply pump to the common rail based on the accelerator opening and the engine speed to a fuel amount having a predetermined decompression characteristic. To do.

Thus, the amount of fuel supplied from the fuel supply pump to the common rail can be variably controlled based on the accelerator opening and the engine speed.
According to the seventh aspect of the invention, the feedback control is permitted at the angle synchronization timing of the next feedback control in which the feedback control is prohibited.

  Thus, in the next feedback control after the feedback control is prohibited, the common rail pressure can be feedback-controlled with high accuracy based on the target common rail pressure and the actual common rail pressure.

According to the eighth aspect of the present invention, when the engine speed is equal to or higher than the predetermined high speed, the accelerator opening calculating means calculates the accelerator opening in angle synchronization.
When the engine speed is in a predetermined high speed range, the time interval of angle synchronization corresponding to the engine speed is shortened. Thereby, even if accelerator opening calculation is implemented by angle synchronization, the delay time until accelerator opening calculation is implemented with respect to accelerator operation can be reduced.

Further, by calculating the accelerator opening not in time synchronization but in angle synchronization, the accelerator angle can be calculated at a predetermined angular interval for feedback control.
As a result, control for prohibiting feedback control when it is determined that the vehicle is decelerating based on the accelerator opening can always be performed at the same angular interval with respect to feedback control. As a result, the above-described effect that the common rail pressure reduction control can be quickly performed by prohibiting the feedback control always occurs at the same angular interval with respect to the feedback control.

Further, the processing load of the CPU or the like can be reduced by selecting an angular timing with a small calculation load and calculating the accelerator opening for an accelerator operation that occurs irregularly.
The functions of the plurality of means provided in the present invention are realized by hardware resources whose functions are specified by the configuration itself, hardware resources whose functions are specified by a program, or a combination thereof. The functions of the plurality of means are not limited to those realized by hardware resources that are physically independent of each other.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
A fuel supply system according to an embodiment of the present invention is shown in FIG.
(Fuel supply system 10)
The fuel supply system 10 of this embodiment is for supplying fuel to, for example, a four-cylinder diesel engine (hereinafter also simply referred to as “engine”) 2 for an automobile, and supplies fuel to the common rail 20. A high-pressure pump 16, a common rail 20 that stores high-pressure fuel, a fuel injection valve 30 that injects high-pressure fuel supplied from the common rail 20 into the combustion chamber of each cylinder of the engine 2, and an electronic control device (Electronic Control) Unit; ECU) 40. The fuel supply system 10 includes a feed pump 14 that pumps fuel from the fuel tank 12 in order to supply fuel from the high-pressure pump 16 to the common rail 20.

  The high-pressure pump 16 as a fuel supply pump is a known pump that pressurizes the fuel sucked into the pressurizing chamber by reciprocating the plunger as the camshaft cam rotates. The metering valve 18 serving as a metering actuator is installed on the suction side of the high-pressure pump 16 and controls the amount of fuel sucked by the high-pressure pump 16 during the suction stroke by current control. Then, by adjusting the fuel intake amount, the fuel discharge amount of the high-pressure pump 16 is adjusted.

  The common rail 20 is provided with a pressure sensor 22 for detecting the internal fuel pressure (common rail pressure), and a pressure reducing valve 24 for reducing the internal fuel pressure by overflowing the internal fuel to the fuel tank 12 side. Yes.

  The engine 2 is provided with a crank angle sensor 32 that detects a crank angle of the engine 2 as a sensor that detects an operating state. The output signal of the crank angle sensor 32 is used not only to detect the rotational angle position of the crankshaft but also to detect the engine speed.

  Further, as other sensors for detecting the driving state, an accelerator sensor 36 for detecting an accelerator opening ACCP that is an operation amount of the accelerator pedal 34 by the driver, a temperature of the cooling water (water temperature), a temperature of the intake air (intake air temperature). The fuel supply system 10 is provided with a temperature sensor or the like for detecting each of the above.

The fuel injection valve 30 is, for example, a known electromagnetic valve that controls the lift of the nozzle needle that opens and closes the nozzle hole with the pressure in the control chamber.
The ECU 40 as a fuel supply control device is constituted by a microcomputer centering on a CPU, ROM, RAM, flash memory and the like. And ECU40 takes in a detection signal from various sensors including pressure sensor 22, crank angle sensor 32, and accelerator sensor 36, and controls an engine operation state. For example, the ECU 40 controls the discharge amount of the high-pressure pump 16, the fuel injection amount of the fuel injection valve 30, the fuel injection timing, and the multistage injection pattern in which pilot injection, post injection, etc. are performed before and after the main injection.

The ECU 40 functions as the following means by a control program stored in the ROM or flash memory.
(Accelerator opening calculation means)
Based on the output signal of the accelerator sensor 36, the ECU 40 calculates the accelerator opening at a time synchronization timing set at a predetermined time interval, as shown in FIG. By calculating the accelerator opening in time synchronization, the change in the accelerator opening can be calculated as soon as possible when the accelerator pedal 34 is operated. In addition to time synchronization, the ECU 40 may calculate the accelerator opening at the following timing.

  (1) When the engine speed is lower than the predetermined speed, the accelerator opening is calculated in time synchronization, and when the engine speed is in a high speed range that is equal to or higher than the predetermined speed, it is synchronized with a predetermined crank angle timing. The accelerator opening is calculated by angle synchronization. As a result, in the high-speed rotation speed region, the accelerator opening can be calculated at a constant angular interval for feedback control based on angle synchronization described later.

(2) Regardless of the engine speed, the accelerator opening is calculated by angle synchronization synchronized with a predetermined crank angle timing.
(Target common rail pressure calculation means)
The ECU 40 calculates the crank angle and the engine speed from the output signal of the crank angle sensor 32. Then, the ECU 40 calculates the target common rail pressure of the common rail 20 based on the accelerator opening calculated by the accelerator opening calculating means and the engine speed.

(Pressure feedback control means)
The ECU 40 performs feedback control for energizing the metering valve 18 and the pressure reducing valve 24 based on the difference between the actual common rail pressure and the target common rail pressure so that the actual common rail pressure detected by the pressure sensor 22 becomes the target common rail pressure. Execute. The ECU 40 idles the fuel injection valve 30 to open the control chamber of the fuel injection valve 30 to the low pressure side within a range where the nozzle needle of the fuel injection valve 30 does not lift, or controls the injection amount of the fuel injection valve 30 as necessary. Thus, the common rail pressure may be feedback controlled.

The ECU 40 performs feedback control by angle synchronization synchronized with a predetermined crank angle timing.
(Deceleration operation determination means)
The ECU 40 calculates the difference between the accelerator opening calculated this time and the accelerator opening calculated previously, and determines that the deceleration operation is commanded when the accelerator opening is decreased by a predetermined angle or more. On the other hand, if the amount of decrease in the accelerator opening is smaller than the predetermined amount, the ECU 40 determines that it is not a deceleration operation.

  This is because when the amount of decrease in the accelerator opening is smaller than the predetermined amount, the amount of pressure that reduces the common rail pressure also decreases, so it is necessary to quickly reduce the common rail pressure by prohibiting feedback control by determining deceleration operation. This is because it is thought that there is no.

(Feedback control prohibition means)
When the ECU 40 determines that the deceleration operation determination unit is the deceleration operation, the ECU 40 prohibits the common rail pressure feedback control by the pressure feedback control unit.

  However, if the difference between the target common rail pressure and the actual common rail pressure is greater than or equal to a predetermined pressure, or if the rate of change of the actual common rail pressure is greater than or equal to the predetermined rate of change, feedback control is prohibited and the metering valve 18 is controlled to control the common rail. When pressure reduction control is performed, the common rail pressure may be excessively reduced. Therefore, even if the deceleration operation determination means determines that the operation is a deceleration operation, if the difference between the target common rail pressure and the actual common rail pressure is greater than or equal to a predetermined pressure, or the change rate of the actual common rail pressure is greater than or equal to a predetermined change rate, the ECU 40 Allows feedback control.

  Further, the ECU 40 permits the common rail pressure feedback control at the angle timing of the next feedback control after prohibiting the feedback control by the pressure feedback control means. Thus, the ECU 40 can perform feedback control of the common rail pressure with high accuracy based on the target common rail pressure and the actual common rail pressure in the next feedback control after the feedback control is prohibited.

(Measurement control means)
The ECU 40 determines that the deceleration operation determination means is a deceleration operation, and the feedback control prohibiting means prohibits the feedback control by the pressure feedback control means, and the accelerator opening and engine speed when it is determined that the deceleration operation is determined As shown in FIG. 2, a command value for quickly reducing the intake amount by the metering valve 18 is calculated at a timing that is not the angle synchronization timing at which the feedback control is performed.

  As a result, as indicated by the solid line from the dotted line in FIG. 2, the discharge amount of the high-pressure pump 16 is quickly reduced and the increase in the common rail pressure is reduced as compared with the case where the command value for the metering valve 18 is calculated in synchronization with the angle. Thus, the common rail pressure can be quickly reduced.

  The ECU 40 may uniformly set the intake amount to 0 by the metering valve 18, or based on the amount of decrease in the accelerator opening or the accelerator opening after the accelerator operation commanding the deceleration operation and the engine speed. Alternatively, the intake amount by the metering valve 18 may be calculated variably so as to have a preset deceleration characteristic. As a result, the inhalation amount may be set to zero.

  Since the common rail pressure reduction control when the feedback control is prohibited is performed by the intake amount control by the metering valve 18 in the same manner as when the feedback control is allowed, the common rail pressure reduction control when the feedback control is prohibited is performed. Easy.

In addition to the metering valve 18, the ECU 40 may calculate a control amount for the pressure reducing valve 24 or the fuel injection valve 30 to reduce the common rail pressure.
(Common rail pressure control during deceleration operation)
Next, the common rail pressure control at the time of the deceleration operation command will be described based on the feedback control prohibiting routine 1 in FIG. 3 and the feedback control prohibiting routine 2 in FIG. 3 and 4, “S” represents a step. The routines of FIGS. 3 and 4 are always executed.

(Feedback control prohibiting routine 1)
In S300 of FIG. 3, the ECU 40 calculates the accelerator opening based on the output signal of the accelerator sensor 36 at time synchronization timing.

  In step S302, the ECU 40 determines whether the deceleration operation is being performed by determining whether the amount of decrease in the accelerator opening calculated this time is greater than or equal to a predetermined amount with respect to the previously calculated accelerator opening. If the decrease amount of the accelerator opening calculated this time is smaller than the predetermined amount with respect to the accelerator opening calculated last time (S302: No), the ECU 40 determines that it is not a deceleration operation and ends this routine.

  If the amount of decrease in the accelerator opening calculated this time with respect to the previously calculated accelerator opening is greater than or equal to a predetermined amount (S302: Yes), the ECU 40 determines that the operation is decelerating. In S304, the ECU 40 determines whether the deceleration state is appropriate, that is, whether the difference between the target common rail pressure and the actual common rail pressure is equal to or less than a predetermined pressure, and the rate of change of the actual common rail pressure is equal to or less than a predetermined value. . Absolute values are used for the difference between the target common rail pressure and the actual common rail pressure, and the rate of change of the actual common rail pressure.

  If the difference between the target common rail pressure and the actual common rail pressure is greater than the predetermined pressure, or the change rate of the actual common rail pressure is greater than the predetermined value (S304: No), the ECU 40 ends this routine.

  When the difference between the target common rail pressure and the actual common rail pressure is equal to or less than the predetermined pressure and the change rate of the actual common rail pressure is equal to or less than the predetermined value (S304: Yes), the ECU 40 in S306 controls the metering valve by feedback control of the common rail pressure. 18 is prohibited from reflecting the control command value.

  In S308, the ECU 40 calculates a command value for reducing the intake amount of the high-pressure pump 16 by controlling the metering valve 18 based on the engine speed and the accelerator opening calculated in S300.

In S310, the ECU 40 sets the command value calculated in S308 as the control value of the metering valve 18.
(Feedback control prohibiting routine 2)
In S320 of FIG. 4, the ECU 40 determines whether feedback control is prohibited. If the feedback control is not prohibited (S320: No), the ECU 40 ends this routine.

  If the feedback control is prohibited, in S322, the ECU 40 determines whether the angle synchronization timing for performing the next feedback control has come. If the angle synchronization timing for executing the next feedback control has not been reached (S322: No), the ECU 40 ends this routine.

  When the angle synchronization timing for performing the next feedback control is reached (S322: Yes), the ECU 40 permits the feedback control in S324. Thereby, feedback control of the common rail pressure is resumed at a predetermined angle synchronization timing including the current angle synchronization timing.

  According to the present embodiment described above, if it is determined that the deceleration operation is performed based on the accelerator opening, the control of the metering valve 18 by the common rail pressure feedback control is prohibited. Then, a command value for the metering valve 18 is calculated based on the accelerator opening and the engine speed when it is determined that the deceleration operation is performed, and the discharge amount of the high-pressure pump 16 is reduced. Thus, the common rail pressure can be quickly reduced before the feedback control is performed at the next angle synchronization timing.

[Other Embodiments]
In the above embodiment, the discharge amount of the high-pressure pump 16 is regulated by controlling the suction amount of the high-pressure pump 16 by the metering valve 18 as a metering actuator installed on the suction side of the high-pressure pump 16. On the other hand, the discharge amount of the high-pressure pump 16 may be measured by a metering valve installed on the discharge side of the high-pressure pump 16. Further, a metering actuator may be installed at any position as long as the amount of fuel supplied from the high-pressure pump 16 to the common rail 20 can be metered.

  As described above, the present invention is not limited to the above-described embodiment, and can be applied to various embodiments without departing from the gist thereof.

The block diagram which shows the fuel supply system by this embodiment. The time chart which shows the pressure reduction control of the common rail pressure at the time of deceleration driving | operation determination. 5 is a flowchart showing a feedback control prohibiting routine 1; 6 is a flowchart showing a feedback control prohibiting routine 2;

Explanation of symbols

2: diesel engine (internal combustion engine), 10: fuel supply system, 16: high pressure pump (fuel supply pump), 18: metering valve (metering actuator), 20: common rail, 30: fuel injection valve, 40: ECU ( (Fuel supply control device, accelerator opening calculation means, pressure feedback control means, deceleration operation determination means, feedback control prohibition means, metering control means)

Claims (9)

Pressure feedback control means for accumulating the fuel discharged from the fuel supply pump and feedback-controlling the pressure of the common rail supplied to the internal combustion engine with angle synchronization;
An accelerator opening calculating means for calculating the accelerator opening at a time synchronization or an angle synchronization timing different from the feedback control;
Deceleration operation determining means for determining whether the operation is a deceleration operation based on the accelerator opening;
A feedback control prohibiting means for prohibiting the feedback control by the pressure feedback control means when the deceleration determination means determines that the operation is a deceleration operation;
A fuel supply control device comprising:   2. The fuel supply control device according to claim 1, wherein the deceleration operation determination unit determines that the vehicle is decelerating when the amount of decrease in the accelerator opening is equal to or greater than a predetermined amount.   Even if the deceleration operation determination unit determines that the feedback control prohibiting unit is decelerating, the difference between the target common rail pressure of the common rail and the actual common rail pressure is greater than or equal to a predetermined pressure, or a change in the actual common rail pressure The fuel supply control device according to claim 1 or 2, wherein the feedback control by the pressure feedback control means is permitted when the rate is equal to or greater than a predetermined change rate. The pressure feedback control means feedback controls the pressure of the common rail by controlling a metering actuator that meteres the amount of fuel supplied from the fuel supply pump to the common rail,
When the feedback control prohibiting unit prohibits the feedback control because the deceleration determining unit determines that it is a deceleration operation, the amount of fuel supplied from the fuel supply pump to the common rail is decreased by the metering actuator. The fuel supply control device according to any one of claims 1 to 3, further comprising metering control means for reducing the pressure of the common rail.   The metering control means controls the metering actuator and sets the fuel amount supplied from the fuel supply pump to the common rail to a fuel amount at which the pressure of the common rail has a predetermined pressure reduction characteristic. The fuel supply control device according to claim 4.   The metering control means sets the fuel amount supplied from the fuel supply pump to the common rail based on the accelerator opening and the engine speed to a fuel amount having the predetermined decompression characteristic. The fuel supply control device according to claim 5.   The feedback control prohibiting unit permits the feedback control by the pressure feedback control unit at an angle synchronization timing of the next feedback control in which the feedback control by the pressure feedback control unit is prohibited. The fuel supply control device according to any one of claims 1 to 6.   The fuel supply according to any one of claims 1 to 7, wherein when the engine speed is in a predetermined high speed range, the accelerator opening calculating means calculates the accelerator opening in an angle-synchronized manner. Control device. A common rail for supplying the accumulated fuel to the internal combustion engine;
A fuel supply pump for supplying pressurized fuel to the common rail;
A metering actuator for metering the amount of fuel supplied to the common rail by the fuel supply pump;
The fuel supply control device according to any one of claims 1 to 8,
A fuel supply system comprising:

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