Injection control device of internal combustion engine

Abstract

A fuel injection control device (ECU) for controlling injection supply of fuel to an engine is applied to an injector that has a valve body formed with a fuel injection hole, a needle accommodated in the valve body for opening and closing the injection hole, and a piezoelectric element for driving the needle such that the needle reciprocates and that can continuously adjust an injection rate in accordance with an injection command signal to the piezoelectric element. The fuel injection control device senses a fuel pressure waveform indicating a transition of fuel pressure fluctuation accompanying a predetermined injection of the injector based on an output of a fuel pressure sensor and calculates an injection command signal for approximating a predetermined injection parameter concerning the predetermined injection to a reference value of the parameter based on the sensed fuel pressure waveform.

1 . A fuel injection control device applied to an injector that has a valve body formed with a fuel injection hole, a valve member accommodated in the valve body for opening and closing the injection hole, and an actuator for driving the valve member such that the valve member reciprocates and that is structured to be able to continuously adjust an injection rate of the injector indicating a fuel injection quantity per unit time in accordance with an actuator operation signal to the actuator, the fuel injection control device comprising:
 a fuel pressure sensing means for sensing a fuel pressure waveform indicating a transition of a fuel pressure fluctuation accompanying a predetermined injection of the injector; and   an operation signal calculating means for calculating the actuator operation signal for approximating a predetermined injection parameter concerning the predetermined injection to a reference value of the parameter based on the fuel pressure waveform sensed by the fuel pressure sensing means.   
   
   
       2 . The fuel injection control device as in  claim 1 , wherein the operation signal calculating means calculates the actuator operation signal concerning the predetermined injection during execution of the predetermined injection, the fuel injection control device further comprising:
 an operation signal setting means for setting the actuator operation signal calculated by the operation signal calculating means as a command concerning the predetermined injection during the execution of the predetermined injection.   
   
   
       3 . The fuel injection control device as in  claim 2 , wherein
 the operation signal calculating means calculates an injection start timing of the predetermined injection based on the fuel pressure waveform and calculates the actuator operation signal subsequent to the injection start timing of the same injection based on a deviation of the injection start timing from a reference timing thereof to approximate a total injection quantity of one injection as the injection parameter to a reference value of the parameter.   
   
   
       4 . The fuel injection control device as in  claim 2 , wherein
 the operation signal calculating means calculates an integration value of the injection rate from an injection start to a predetermined timing of the predetermined injection or a correlation value of the integration value based on the fuel pressure waveform and calculates the actuator operation signal subsequent to the predetermined timing of the same injection based on a deviation of the integration value or the correlation value from a reference value thereof to approximate a total injection quantity of one injection as the injection parameter to a reference value of the parameter.   
   
   
       5 . The fuel injection control device as in  claim 2 , wherein
 the operation signal calculating means calculates an injection rate at a predetermined timing of the predetermined injection based on the fuel pressure waveform and calculates the actuator operation signal subsequent to the predetermined timing of the same injection based on a deviation of the injection rate from a reference value thereof to approximate a total injection quantity of one injection as the injection parameter to a reference value of the parameter.   
   
   
       6 . The fuel injection control device as in  claim 5 , wherein
 the injection rate at the predetermined timing is the maximum injection rate in the predetermined injection.   
   
   
       7 . The fuel injection control device as in  claim 2 , wherein
 the operation signal calculating means calculates a signal for deciding an injection end timing of the predetermined injection as the actuator operation signal.   
   
   
       8 . The fuel injection control device as in  claim 1 , further comprising:
 an operation signal setting means for setting the actuator operation signal calculated by the operation signal calculating means as a command concerning a certain injection of the same kind as the predetermined injection, which is executed on the occasion of the calculation of the actuator operation signal, if the certain injection is executed after an end of the predetermined injection.   
   
   
       9 . The fuel injection control device as in  claim 8 , wherein
 the operation signal calculating means calculates a rising angle or a falling angle of an injection rate waveform indicating a transition of the injection rate in the predetermined injection based on the fuel pressure waveform and calculates the actuator operation signal for approximating the rising angle or the falling angle of the injection rate waveform of the injection as the injection parameter to a reference value of the parameter based on a deviation of the rising angle or the falling angle from a reference angle thereof.   
   
   
       10 . The fuel injection control device as in  claim 8 , wherein
 the operation signal calculating means calculates a position of an apex of an injection rate waveform indicating a transition of the injection rate in the predetermined injection based on the fuel pressure waveform and calculates the actuator operation signal for approximating the position of the apex of the injection rate waveform of the injection as the injection parameter to a reference value of the parameter based on a deviation of the position of the apex from a position of a reference point thereof.   
   
   
       11 . The fuel injection control device as in  claim 8 , wherein
 the operation signal calculating means calculates the maximum injection rate of an injection rate waveform indicating a transition of the injection rate in the predetermined injection based on the fuel pressure waveform and calculates the actuator operation signal for approximating the maximum injection rate of the injection rate waveform of the injection as the injection parameter to a reference value of the parameter based on a deviation of the maximum injection rate from a reference value thereof.   
   
   
       12 . The fuel injection control device as in  claim 8 , wherein
 the operation signal calculating means calculates an injection rate in a stable interval, in which the injection rate is maintained at a constant value, in an injection rate waveform indicating a transition of the injection rate in the predetermined injection based on the fuel pressure waveform and calculates the actuator operation signal for approximating the injection rate in the stable interval of the injection rate waveform of the injection as the injection parameter to a reference value of the parameter based on a deviation of the injection rate from a reference value thereof.   
   
   
       13 . The fuel injection control device as in  claim 9 , wherein
 the injection rate waveform takes the form of one of a triangle, a trapezoid and a rectangle or the form of a diagram as a combination of multiplicity of at least one kind of the triangle, the trapezoid and the rectangle.   
   
   
       14 . The fuel injection control device as in  claim 1 , wherein
 the fuel injection control device is applied to a pressure accumulator type fuel injection system having a pressure accumulator for accumulating high-pressure fuel to be supplied to the injector and at least one fuel pressure sensor for sensing pressure of the fuel flowing through an inside of a fuel passage extending from a fuel discharge hole of the pressure accumulator to the injection hole of the injector at a predetermined point downstream of a neighborhood of the fuel discharge hole of the pressure accumulator with respect to a fuel flow direction, and   the fuel pressure sensing means senses the fuel pressure waveform by sequentially sensing the fuel pressure based on an output of the fuel pressure sensor.   
   
   
       15 . The fuel injection control device as in  claim 14 , wherein
 the fuel pressure sensor is provided inside or near the injector.   
   
   
       16 . The fuel injection control device as in  claim 14 , wherein
 the fuel pressure sensor is provided in a fuel discharge pipe of the pressure accumulator at a position closer to the fuel injection hole of the injector than the pressure accumulator.   
   
   
       17 . The fuel injection control device as in  claim 1 , wherein
 the fuel injection control device is applied to a pressure accumulator type fuel injection system having a pressure accumulator for accumulating high-pressure fuel to be supplied to the injector, a fuel pulsation reducing means provided in a connection between the pressure accumulator and a fuel discharge pipe of the pressure accumulator for reducing a fuel pulsation transmitted to the pressure accumulator through the fuel discharge pipe, and at least one fuel pressure sensor for sensing pressure of the fuel flowing through an inside of a fuel passage extending from the pressure accumulator to the injection hole of the injector at a predetermined point downstream of the fuel pulsation reducing means with respect to a fuel flow direction, and   the fuel pressure sensing means senses the fuel pressure waveform by sequentially sensing the fuel pressure based on an output of the fuel pressure sensor.   
   
   
       18 . The fuel injection control device as in  claim 17 , wherein
 the fuel pulsation reducing means is constituted by an orifice, a flow damper or a combination of the orifice and the flow damper.   
   
   
       19 . The fuel injection control device as in  claim 17 , wherein
 the fuel pressure sensor is provided inside or near the injector.   
   
   
       20 . The fuel injection control device as in  claim 17 , wherein
 the fuel pressure sensor is provided in a fuel discharge pipe of the pressure accumulator at a position closer to the fuel injection hole of the injector than the pressure accumulator.   
   
   
       21 . The fuel injection control device as in  claim 1 , wherein
 the actuator is a piezoelectric element that continuously changes an extension-contraction amount thereof in accordance with a continuous change of the actuator operation signal.