Fuel injection device and adjustment method thereof

Patent metadata

Field	Value
Publication number	US-9588016-B2
Application number	US-93066807-A
Country	US
Kind code	B2
Filing date	Oct 31, 2007
Priority date	Nov 14, 2006
Publication date	Mar 7, 2017
Grant date	Mar 7, 2017

Abstract

A fuel injection device (fuel supply system) of a common rail type fuel injection system for an engine includes a pressure sensor disposed in a fuel inlet of an injector for measuring a fuel pressure at a position where the sensor is disposed and an ECU for sensing various kinds of pressure fluctuations associated with the injection including a pressure leak due to an injection operation of the injector and waving characteristics due to actual injection thereof based on sensor outputs from the pressure sensor. The ECU serially obtains the sensor outputs from the pressure sensor at intervals of 20 μsec.

First claim

What is claimed is:

1. A fuel injection device of a common rail type fuel injection system for an engine, the fuel injection device comprising:
at least one fuel passage pressure sensor disposed in a fuel passage between a point of a pipe connected to a fuel discharge port of a common rail apart from the common rail by a certain distance and a fuel injection hole of an injector connected to the pipe, the sensor measuring a fuel pressure at a position where the sensor is disposed;
a pressure fluctuation sensing device configured to sense a pressure fluctuation caused by at least one of an injection operation of the injector and actual injection actually performed through the injection operation based on a sensor output from the fuel passage pressure sensor; and
an injection characteristic detecting device configured to detect at least one injection characteristic of the injector based on the pressure fluctuation sensed by the pressure fluctuation sensing device, wherein
the injection characteristic detected by the injection characteristic detecting device is at least one of an actual injection rate and a fluctuation of the actual injection rate in an injection period of the injector, wherein the actual injection rate is an instantaneous injection quantity of fuel in a time interval shorter than the injection period;
wherein the pressure fluctuation sensing device is configured to obtain multiple pressure sensor values, which are respectively sensed at multiple timings including a timing near an injection timing during the injection, from the at least one fuel passage pressure sensor at time intervals which are shorter than the injection period; and
wherein the injection characteristic detecting device is configured to:
calculate a difference value between each of the multiple pressure sensor values and a pressure value, which is caused by a pressure decrease from a common rail pressure in the common rail due to fuel leak after start of an injection start command, to obtain a series of difference values including the difference value; and
detect the actual injection rate based on the series of difference values.

2. The fuel injection device according to claim 1 , further comprising:
a fuel pulsation reducing device provided in a connection portion between the common rail and the pipe configured to reduce a fuel pulsation transmitted to the common rail via the pipe, wherein
the fuel passage pressure sensor is disposed on the injector side of the fuel pulsation reducing device.

3. The fuel injection device according to claim 2 , wherein
the fuel pulsation reducing device is one or a combination of an orifice and a flow damper.

4. The fuel injection device according to claim 1 , wherein
the pressure fluctuation sensing device is configured to sense the pressure fluctuation caused by at least one of the injection operation of the injector and the actual injection thereof in the form of a pressure transition waveform by sequentially obtaining the sensor outputs from the fuel passage pressure sensor at intervals short enough to draw a track of the pressure transition waveform with the sensor outputs.

5. The fuel injection device according to claim 1 , wherein
the pressure fluctuation sensing device is configured to sense the pressure fluctuation caused by at least one of the injection operation of the injector and the actual injection thereof by sequentially obtaining the sensor outputs from the fuel passage pressure sensor at intervals shorter than 50 μsec.

6. The fuel injection device according to claim 2 , further comprising:
a period setting device configured to set a sensor output obtaining period for serially obtaining the sensor outputs to a predetermined limited period including at least a pressure fluctuation period during which the pressure fluctuation is caused by the actual injection of the injector.

7. The fuel injection device according to claim 6 , wherein
the period setting device is configured to set start timing of the sensor output obtaining period with respect to injection start command timing of the injector, which is instructed by an injection start command associated with the first injection operation among one or more injections performed by the injector during one combustion cycle of the engine, and to set end timing of the sensor output obtaining period based on the pressure fluctuation after execution of the last injection in the same cycle sensed by the pressure fluctuation sensing device.

8. The fuel injection device according to claim 2 , further comprising:
a stopping period setting device configured to set a stopping period for temporarily stopping the obtainment of the sensor output in a part of a stable pressure period, in which the fuel pressure at the located position of the fuel passage pressure sensor is stable, among the sensor output obtaining period for serially obtaining the sensor outputs.

9. The fuel injection device according to claim 8 , further comprising:
a stable period start detection device configured to detect start timing of the stable pressure period based on the pressure fluctuation sensed by the pressure fluctuation sensing device, wherein
the stopping period setting device is configured to set start timing of the stopping period to the start timing of the stable pressure period detected by the stable period start detection device or to timing a predetermined time after the start timing and is configured to set end timing of the stopping period to injection end command timing instructed by an injection end command to the injector.

10. The fuel injection device according to claim 1 , wherein the engine is a multi-cylinder engine in which all cylinders of the engine are respectively provided with the fuel passage pressure sensors, the fuel injection device comprising:
a grouping device configured to group the cylinders whose pressure fluctuation periods can overlap with each other among all the cylinders of the engine, the pressure fluctuation period being a period during which the pressure fluctuation is caused by the actual injection of the injector, wherein
the pressure fluctuation sensing device is configured to sense the pressure fluctuation of each cylinder included in each group formed by the grouping device and switches between the groups in turn while ending the sensing concerning at least one cylinder in the group, thereby sensing the pressure fluctuation of every cylinder in the engine.

11. The fuel injection device according to claim 1 , wherein the engine is a multi-cylinder engine with a plurality of cylinders for performing combustion in the respective cylinders in turn, all cylinders of the engine being respectively provided with the fuel passage pressure sensors, the fuel injection device further comprising:
a cylinder selecting device configured to select two or three cylinders adjacent to each other with regard to the order of the combustion among all the cylinders included in the engine, wherein
the pressure fluctuation sensing device is configured to sense the pressure fluctuation of each of the two or three cylinders selected by the cylinder selecting device.

12. The fuel injection device according to claim 11 , wherein
the cylinder selecting device is a selection circuit is configured to select a predetermined signal from input signals on a circuit, and
the pressure fluctuation sensing device includes computation circuits respectively for the two or three cylinders selected by the cylinder selecting device to perform computation for simultaneously sensing the pressure fluctuations of the respective cylinders.

13. The fuel injection device according to claim 1 ,

Assignees

• Ishizuka Kouji
• Nakata Kenichirou
• Takeuchi Katsuhiko
• Denso Corp

Inventors

• Ishizuka Kouji
• Nakata Kenichirou
• Takeuchi Katsuhiko

Classifications

• F02D2250/14

  Timing of measurement, e.g. synchronisation of measurements to the engine cycle · CPC title

• F02D2200/0616

  determined by estimation · CPC title

• F02M2200/24

  Fuel-injection apparatus with sensors · CPC title

• F02D41/3836

  Controlling the fuel pressure · CPC title

• F02D2200/0602

  Fuel pressure · CPC title