JP2009138593A - Accumulating type fuel injection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an accumulating type fuel injection device capable of detecting abnormality of a pressure metering valve. <P>SOLUTION: This device comprises a common rail 2 for holding fuel accumulated to a high pressure and supplying it to an injector 5, a high pressure fuel supply pump 4 for supplying high pressure fuel to the common rail 2, a pressure metering valve 14 for controlling delivery from the high pressure fuel supply pump 4 according to a control current to be inputted, and a fuel pressure sensor 7 for detecting the fuel pressure of the common rail 2. The pressure metering valve 14 is controlled according to a fuel pressure detected by the fuel pressure sensor 7 and a target pressure, so as to control the fuel pressure of the common rail 2. It is judged whether the device is under a decelerating operation or not (S100). When it is judged as the decelerating operation, a control current to the pressure metering valve 14 based on the target pressure is changed, and outputted to the pressure metering valve 14 (S120-S160). When the fuel pressure detected by the fuel pressure sensor 7 is not changed after the control current is outputted, the pressure metering valve 14 is judged as abnormal (S180-S220). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to an accumulator fuel injection device that supplies fuel to an injector from a common rail in which high pressure fuel is accumulated, and more particularly to an accumulator fuel injection that determines an abnormality of a pressure metering valve that controls discharge from a high pressure fuel supply pump. Relates to the device.

  Conventionally, as disclosed in Patent Document 1, in an accumulator type fuel injection device that supplies fuel from a common rail to an injector, high pressure fuel is supplied from a high pressure fuel supply pump to the common rail, and is also supplied to a high pressure fuel supply pump by a pressure metering valve. The fuel pressure of the common rail is controlled by changing the amount of discharge from the high-pressure fuel supply pump by adjusting the amount of intake air.

At this time, the fuel pressure of the common rail is detected by a sensor, and the control current output to the pressure metering valve is fed back so that the difference between the fuel pressure and the target pressure is reduced based on the detected fuel pressure and the target pressure. I have control. Moreover, in order to correct the machine difference variation of the high-pressure fuel supply pump or the like, a machine difference learning is performed to constitute a stable device that absorbs the machine difference variation.
JP 2004-225555 A

  However, in such a conventional device, for example, the valve body is slid in accordance with a control current input to the pressure metering valve to adjust the intake amount to the high-pressure fuel supply pump. If foreign matter bites into the sliding surface of the pressure metering valve body or adheres to highly viscous fuel, the sliding resistance of the pressure metering valve body temporarily increases, and the pressure metering valve May be difficult to move.

  In this case, even if the control current input to the pressure metering valve is small and a change output smaller than the increased sliding resistance is given, the valve body of the pressure metering valve does not move. When a change output corresponding to the current of the control current value that overcomes the sliding resistance is given, the pressure metering valve starts to move.

  When feedback control of the fuel pressure of the common rail is performed in this state, the valve body of the pressure metering valve does not move with a small control current, and the intake amount of the high-pressure fuel supply pump does not change. For this reason, the discharge control of the high-pressure fuel supply pump is delayed, and the difference between the fuel pressure and the target pressure becomes large.For example, the pressure metering valve is over-corrected to output a control current larger than normal. There was a problem that the fuel pressure overshooted after moving. When the responsiveness deteriorates due to changes over time, foreign matter, highly viscous fuel, etc., there is a problem in that fuel pressure control failure of the common rail occurs and hunting and engine stall occur. Further, during normal traveling, there is a problem that it is impossible to distinguish between a pressure response delay due to an operating state and a pressure response delay due to a sliding failure of the pressure metering valve.

  The subject of this invention is providing the pressure accumulation type fuel-injection apparatus which can detect abnormality of a pressure metering valve.

  In order to achieve this problem, the present invention has taken the following measures in order to solve the problem. That is, an injector that injects fuel into a cylinder of an internal combustion engine, a common rail that holds fuel accumulated at high pressure and supplies the fuel to the injector, a high-pressure fuel supply pump that supplies high-pressure fuel to the common rail, and an input control A pressure metering valve that controls discharge from the high-pressure fuel supply pump in accordance with an electric current; and a fuel pressure detection unit that detects a fuel pressure of the common rail. The fuel pressure detected by the fuel pressure detection unit and a target In the accumulator fuel injection device that controls the pressure metering valve according to a control current based on the pressure to control the fuel pressure of the common rail, a deceleration determination unit that determines whether the vehicle is decelerating, and the deceleration determination A change driver that changes the control current to the pressure metering valve based on the target pressure and outputs the control current to the pressure metering valve when it is determined by the means that the vehicle is decelerating. And an abnormality determining means for determining that the pressure metering valve is abnormal when there is no change in behavior after the control current is output by the change driving means. That is it.

  The abnormality determining means may determine that the pressure metering valve is abnormal when there is no change in the fuel pressure detected by the fuel pressure detecting means after outputting the control current. At this time, the abnormality determining means outputs an abnormality in the pressure metering valve when the fuel pressure detected by the fuel pressure detecting means does not change within a preset period after outputting the control current. You may judge that there is.

In addition, after determining that the deceleration operation is being performed by the deceleration determination unit, whether or not the output of the control current to the pressure metering valve based on the target pressure is further started from the non-discharge state of the high-pressure fuel supply pump. A means for determining during discharge control for determining
The change driving means changes the control current to the pressure metering valve based on the target pressure after starting output of a control current to the pressure metering valve by the discharge control mid-judgment means. It is good also as a structure output to a metering valve.

  The pressure accumulation type fuel injection device of the present invention changes the control current value of the pressure metering valve during the deceleration operation, and determines that the pressure metering valve is abnormal when there is no change in behavior. There is an effect that the abnormality of the pressure metering valve due to highly viscous fuel or the like can be accurately detected.

  By detecting the fuel pressure of the common rail and determining whether or not the behavior has changed due to the change in the fuel pressure, the change in behavior can be easily detected. Further, by determining that there is an abnormality when there is no change in fuel pressure within a preset period, it is possible to accurately determine even if there is a delay time.

  After starting the output of the control current to the pressure metering valve by the judgment means during the discharge control, change the control current to the pressure metering valve based on the target pressure and output to the pressure metering valve to change the behavior Can be reliably detected.

The best mode for carrying out the present invention will be described below in detail with reference to the drawings. FIG. 1 is an overall configuration diagram showing a pressure accumulation type fuel injection device as one embodiment of the present invention.
As shown in FIG. 1, the pressure accumulation type fuel injection device of the present embodiment is applied to, for example, an internal combustion engine 1 as a four-cylinder diesel engine, and is pumped from a common rail 2 that stores high-pressure fuel and a fuel tank 3. A high-pressure fuel supply pump 4 that pressurizes and supplies fuel to the common rail 2, an injector 5 that injects high-pressure fuel supplied from the common rail 2 into the combustion chamber 21 in the cylinder of the internal combustion engine 1, and the injector 5 are electronically controlled. And an electronic control unit (hereinafter referred to as ECU 6).

  The common rail 2 has a target pressure set by the ECU 6 based on the operating state and the like, and accumulates the high-pressure fuel supplied from the high-pressure fuel supply pump 4 to the target pressure. The common rail 2 includes a fuel pressure sensor 7 as a fuel pressure detecting means for detecting the accumulated fuel pressure and outputting it to the ECU 6, and a pressure limiter 8 for limiting the fuel pressure so as not to exceed a preset upper limit value. Is attached.

  The high-pressure fuel supply pump 4 is synchronized with the rotation of the camshaft 9 driven by the internal combustion engine 1, the feed pump 10 driven by the camshaft 9 to pump fuel from the fuel tank 3, and the rotation of the camshaft 9. A plunger 12 that reciprocates in the cylinder 11 is provided. Further, a pressure metering valve 14 for adjusting the amount of fuel drawn from the feed pump 10 into the pressurizing chamber 13 in the cylinder 11 is provided integrally with a main body (not shown) of the high-pressure fuel supply pump 4.

  In the high pressure fuel supply pump 4, when the plunger 12 moves in the cylinder 11 from the top dead center to the bottom dead center, the fuel delivered from the feed pump 10 is adjusted by the pressure metering valve 14, and the intake valve 15 is pushed open and sucked into the pressurizing chamber 13. Thereafter, when the plunger 12 moves in the cylinder 11 from the bottom dead center to the top dead center, the fuel in the pressurizing chamber 13 is pressurized by the plunger 12, and the pressurized fuel passes through the discharge valve 16. Pushed open and pumped to the common rail 2.

  The pressure metering valve 14 slides a valve body (not shown) in accordance with the input control current to adjust the fuel delivered from the feed pump 10, and from the pressurizing chamber 13 of the high-pressure fuel supply pump 4 to the common rail 2. The discharge amount to be discharged is changed. In the present embodiment, the larger the control current value input to the pressure metering valve 14, the smaller the amount of fuel drawn into the pressurizing chamber 13.

  The injector 5 is mounted for each cylinder of the internal combustion engine 1, and is connected to the common rail 2 via the high-pressure pipe 17. The injector 5 includes a solenoid valve 22 that operates based on a command from the ECU 6 and a nozzle 23 that injects fuel when the solenoid valve 22 is energized.

 The solenoid valve 22 opens and closes a low-pressure passage (not shown) that leads to a low-pressure side from a pressure chamber (not shown) to which the high-pressure fuel of the common rail 2 is applied. Shut off the low pressure passage when stopping.

  The nozzle 23 incorporates a needle (not shown) that opens and closes the nozzle hole, and the fuel pressure in the pressure chamber urges the needle in the valve closing direction (direction in which the nozzle hole is closed). Accordingly, when the low pressure passage is opened by energization of the electromagnetic valve 22 and the fuel pressure in the pressure chamber decreases, the needle rises in the nozzle 23 and opens (opens the nozzle hole), thereby being supplied from the common rail 2. High pressure fuel is injected from the nozzle hole. On the other hand, when the low pressure passage is blocked by stopping energization of the electromagnetic valve 22 and the fuel pressure in the pressure chamber rises, the needle descends in the nozzle 23 and closes, thereby terminating the injection.

  The ECU 6 includes a rotational speed sensor 18 that detects the rotational speed of the internal combustion engine 1, an accelerator opening sensor 20 that detects an accelerator opening corresponding to the amount of depression of the accelerator pedal 19, and a fuel that detects fuel pressure in the common rail 2. Pressure sensors 7 and the like are connected, and based on sensor information detected by these sensors, the target pressure of the common rail 2 and the injection timing and injection amount suitable for the operating state of the internal combustion engine 1 are calculated. Accordingly, the pressure metering valve 14 and the electromagnetic valve 22 of the injector 5 are electronically controlled.

Next, the abnormality determination process executed by the ECU 6 will be described based on the flowchart shown in FIG.
First, it is determined whether or not the vehicle is decelerating (step 100, hereinafter referred to as S100, and so on). When the accelerator opening detected by the accelerator opening sensor 20 is 0 and the fuel injection amount from the injector 5 under the control of the ECU 6 is 0, it is determined that the vehicle is decelerating.

  When the accelerator opening is detected as 0, the ECU 6 sets the fuel injection amount from the injector 5 to 0, the fuel is not discharged from the injector 5, and there is no change in the fuel pressure in the common rail 2 due to the fuel injection. .

  If it is determined that the vehicle is decelerating (S100: YES), the control current output to the pressure metering valve 14 is controlled to control the amount of fuel discharged from the high-pressure fuel supply pump 4 to the common rail 2. Is determined (S110).

  When the accelerator opening is set to 0, the ECU 6 sets the fuel pressure of the common rail 2 to a low target pressure. As shown in FIG. 3, when the accelerator opening is set to 0, a large control current is output to the pressure metering valve 14, and the amount of fuel sucked into the pressurizing chamber 13 is adjusted to almost zero, The amount of fuel from the high-pressure fuel supply pump 4 to the common rail 2 is set to a non-discharge state. Then, the control current to the pressure metering valve 14 is gradually reduced to gradually recover the discharge amount from the high-pressure fuel supply pump 4 to the common rail 2 so that the fuel pressure in the common rail 2 becomes the target pressure. .

  In this embodiment, the fuel discharge control is performed from the time when the fuel discharge from the high-pressure fuel supply pump 4 is changed from the non-discharge state to the fuel discharge state (S2 in FIG. 3). When it is determined that the fuel discharge control is being performed (S110: YES), the abnormality determination logic operation flag is turned ON (S120).

  On the other hand, when it is determined that the vehicle is not decelerating by executing the process of S100 (S100: NO), or when it is determined that the fuel discharge control is not being executed by executing the process of S110 (S110: NO), The abnormality determination logic operation flag is turned off (S125). Thereafter, this control process is repeated. When the deceleration operation is not being performed or when the fuel discharge control is not being performed, the fuel pressure in the common rail 2 fluctuates with the fuel injection or the fuel supply from the high-pressure fuel supply pump 4, and the following abnormality determination of the pressure metering valve 14 is performed. Not suitable for.

  After turning on the abnormality determination logic operation flag by executing the process of S120, the control current value of the pressure metering valve 14 is calculated (S130). As shown in FIG. 5, the control current value output to the pressure metering valve 14 is proportional to the pressure change amount of the common rail 2, and the control current value for controlling the pressure of the common rail 2 to the target pressure is calculated. In the present embodiment, the control current value is gradually decreased while the control process is repeatedly executed so that the fuel pressure in the common rail 2 gradually becomes the target pressure.

  Next, it is determined whether or not the abnormality determination logic operation flag has been switched from OFF to ON (S140). If the abnormality determination logic operation flag has been switched from OFF to ON (S140: YES), a control current value for minutely driving the pressure metering valve 14 is calculated (S150).

  For example, as shown in FIG. 5, in order to change the fuel pressure in the common rail 2, a control current value corresponding to the pressure change amount is calculated. This control current value is not a large control current value that overcomes the increased sliding resistance caused by foreign matter biting into the sliding surface of the valve body of the pressure metering valve 14 or adhesion of highly viscous fuel. This is a minute control current value corresponding to the amount of pressure change that does not significantly affect the feedback control of the fuel pressure of the common rail 2.

  After calculating the control current value for the minute driving, the control current value calculated by executing the process of S130 and the control current value calculated by the process of S150 are added to calculate the final control current value. (S160), the control current of the control current value is output to the pressure metering valve 14.

  The final control current value is changed by adding or subtracting the control current value for minutely driving the valve body of the pressure metering valve 14 to the control current value based on the target pressure calculated by the processing of S130. Any value can be used. As shown in FIG. 3, the final control current value may be calculated by adding the control current value calculated by the process of S150 to the control current value based on the target pressure calculated by the process of S130. At that time, the discharge amount from the high-pressure fuel supply pump 4 is controlled to decrease. Also, as shown in FIG. 4, the final control current value may be calculated by subtracting the control current value calculated by the process of S150 from the control current value based on the target pressure calculated by the process of S130. At that time, the discharge amount from the high-pressure fuel supply pump 4 is controlled to increase.

  Next, after outputting the final control current value to the pressure metering valve 14, it is determined whether or not a preset first predetermined time T1 has elapsed (S170). Until the first predetermined time T1 elapses (S170: NO), the processing of S100 and subsequent steps is repeatedly executed, and in the execution of the processing of S140, it is determined that the abnormality determination logic operation flag remains ON and is not switched ( S140: NO), the control current value based on the target pressure calculated by the process of S130 is calculated as it is as the final control current value, and is output to the pressure metering valve 14.

  When the first predetermined time T1 elapses (S6 in FIG. 3) (S170: YES), the amount of change in the fuel pressure in the common rail 2 detected by the fuel pressure sensor 7 is calculated (S180). There is a delay time from when the control current value is output to the pressure metering valve 14 until the fuel pressure in the common rail 2 actually changes and is detected by the fuel pressure sensor 7. The first predetermined time T1 described above corresponds to this delay time, and the time before the fuel pressure in the common rail 2 changes after the control current value is output to the pressure metering valve 14 is defined as the first predetermined time T1. It is set. The first predetermined time T1 may be determined by experiments or the like.

  Next, it is determined whether or not the calculated change amount of the fuel pressure is greater than or equal to a predetermined value set in advance (S190). The fuel pressure sensor 7 detects the fuel pressure in the common rail 2 every predetermined time for repeatedly executing this control process, and calculates the change amount of each detected fuel pressure every predetermined time. When the change amount of the fuel pressure is equal to or greater than the predetermined value (S190: YES), it is determined that the valve body of the pressure metering valve 14 has slid normally, and the pressure metering valve 14 is set to normal (S200). . For example, a signal indicating that the pressure metering valve 14 is normal is output to a failure diagnosis device or the like. Since the change amount of the fuel pressure is proportional to the minute drive control current value calculated by the process of S150, the predetermined value to be compared may be changed according to the minute drive control current value.

  In this way, immediately after the abnormality determination logic operation flag is switched from OFF to ON during deceleration operation, the control current value is changed momentarily, and the pressure metering valve 14 is operating normally when the fuel pressure changes. Judge.

  On the other hand, when it is determined that the change amount of the fuel pressure is not equal to or greater than the predetermined value (S190: NO), it is determined whether or not the second predetermined time T2 has elapsed from the output of the control current value for the minute drive (S210). When the second predetermined time T2 has not elapsed, this control process is repeatedly executed until the second predetermined time T2 elapses, and the fuel in the common rail 2 detected by the fuel pressure sensor 7 by the processes of S180 and S190. It is determined whether or not the amount of change in pressure is greater than or equal to a predetermined value.

  If it is not determined that the amount of change in the fuel pressure is greater than or equal to the predetermined value by executing the process of S190 until the second predetermined time T2 elapses, the second predetermined time T2 elapses (S210: YES) ), The valve body of the pressure metering valve 14 does not slide normally, and the pressure metering valve 14 is abnormal (S220). For example, a signal indicating that the pressure metering valve 14 is abnormal is output to a failure diagnosis device or the like.

  Immediately after the abnormality determination logic operation flag is switched from OFF to ON during deceleration operation, the control current value is changed momentarily, and when the fuel pressure does not change, the pressure metering valve 14 is determined to be abnormal. When it is determined that the pressure metering valve 14 is abnormal, the control gain of feedback control is changed, an indication that the pressure metering valve 14 is abnormal, and the idling speed is increased to prevent engine stall due to pressure drop. In order to prevent engine stall due to pressure drop, a process such as increasing the target pressure may be performed.

  It should be noted that the execution of the process of S100 serves as a deceleration determination means, the execution of the process of S110 serves as a discharge control determining means, the execution of the processes of S120 to S160 serves as a change drive means, and S170 to S190 and S210, S220 Execution of processing serves as an abnormality determination means.

  In the present embodiment, whether the pressure metering valve 14 is normal or abnormal is determined based on whether or not the change amount of the fuel pressure detected by the fuel pressure sensor 7 is equal to or greater than a predetermined value. Not only the amount of change but also the amount of change in the rotational speed of the internal combustion engine 1 is detected, and whether the pressure metering valve 14 is normal or abnormal is determined by whether or not the amount of change in the rotational speed is greater than or equal to a predetermined value. The behavior that changes when the control current value of the pressure metering valve 14 is changed may be detected and judged.

  The present invention is not limited to such embodiments as described above, and can be implemented in various modes without departing from the gist of the present invention.

1 is an overall configuration diagram showing a pressure accumulation type fuel injection device as one embodiment of the present invention. It is a flowchart which shows an example of the abnormality determination process performed by the electronic control unit of this embodiment. It is a timing chart which shows the relationship between the accelerator opening of this embodiment, a control electric current value, and a fuel pressure. It is a timing chart which shows the relationship between the accelerator opening of another embodiment, a control electric current value, and fuel pressure. It is a graph which shows the relationship between the control current and pressure change amount of this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Common rail 3 ... Fuel tank 4 ... High-pressure fuel supply pump 5 ... Injector 7 ... Fuel pressure sensor 8 ... Pressure limiter 9 ... Cam shaft 10 ... Feed pump 11 ... Cylinder 12 ... Plunger 13 ... Pressurizing chamber 14 ... Pressure metering valve 17 ... high pressure pipe 18 ... rotation speed sensor 19 ... accelerator pedal 20 ... accelerator opening sensor 21 ... combustion chamber

Claims (4)

An injector for injecting fuel into a cylinder of the internal combustion engine;
A common rail that holds fuel accumulated at a high pressure and supplies the fuel to the injector;
A high pressure fuel supply pump for supplying high pressure fuel to the common rail;
A pressure metering valve for controlling discharge from the high-pressure fuel supply pump in accordance with an input control current;
Fuel pressure detecting means for detecting the fuel pressure of the common rail,
In an accumulator fuel injection device that controls the pressure metering valve according to a control current based on the fuel pressure detected by the fuel pressure detecting means and a target pressure, thereby controlling the fuel pressure of the common rail,
Deceleration determination means for determining whether or not the vehicle is decelerating;
A change driving means for changing the control current to the pressure metering valve based on the target pressure and outputting to the pressure metering valve when the deceleration determining means determines that the vehicle is decelerating; and
An accumulator fuel injection apparatus comprising: an abnormality determining unit that determines that the pressure metering valve is abnormal when there is no change in behavior after the control current is output by the change driving unit. The abnormality determination means determines that the pressure metering valve is abnormal when there is no change in the fuel pressure detected by the fuel pressure detection means after outputting the control current. 2. A pressure-accumulation fuel injection device according to 1. The abnormality determining means determines that the pressure metering valve is abnormal when there is no change in the fuel pressure detected by the fuel pressure detecting means within a preset period after outputting the control current. The pressure-accumulation fuel injection device according to claim 2, wherein After determining that the deceleration operation is being performed by the deceleration determination unit, it is further determined whether or not output of a control current to the pressure metering valve based on the target pressure is started from a non-discharge state of the high-pressure fuel supply pump. A means for determining during discharge control,
The change driving means changes the control current to the pressure metering valve based on the target pressure after starting output of a control current to the pressure metering valve by the discharge control mid-judgment means. The accumulator fuel injection device according to any one of claims 1 to 3, wherein the accumulator fuel injection device outputs to a metering valve.

Images