Fuel injection control device for internal combustion engine

• US 7,620,490 B2
• Filed: 03/08/2006
• Issued: 11/17/2009
• Est. Priority Date: 03/09/2005
• Status: Expired due to Fees

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Matsunaga, Akio
• Primary Examiner(s): Cronin; Stephen K
• Assistant Examiner(s): Hoang; Johnny H
• Application Number:
  US11/885,998
• Publication Number:
  US 20080275627A1
• Time in Patent Office: 1,350 Days
• Field of Search: 701101-104, 701/108, 701/109, 123/568.11, 123/568.16, 123/568.21, 123434-436, 606/052
• US Class Current: 701/108
• CPC Class Codes: F02D 2250/38 Control for minimising smoke emissions, e.g. by applying smoke limitations on the fuel injection amount
• CPC Class Codes: F02D 41/0065 Specific aspects of external EGR control constructional details of EGR system F02M26/00
• CPC Class Codes: F02D 41/144 Sensor in intake manifold
• CPC Class Codes: F02D 41/1456 with sensor output signal being linear or quasi-linear with the concentration of oxygen
• CPC Class Codes: F02M 26/05 High pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust system upstream of the turbine and reintroduced into the intake system downstream of the compressor
• CPC Class Codes: F02M 26/10 having means to increase the pressure difference between the exhaust and intake system, e.g. venturis, variable geometry turbines, check valves using pressure pulsations or throttles in the air intake or exhaust system
• CPC Class Codes: F02M 26/23 Layout, e.g. schematics
• CPC Class Codes: F02M 26/46 for determining the characteristics of gases, e.g. composition
• CPC Class Codes: F02M 26/48 EGR valve position sensors details of the sensor installation in the valve housing F02M26/72

Abstract

The invention provides a fuel injection control device for an internal combustion engine that can improve the accuracy of combustion control regarding smoke suppression. The fuel injection control device is applied to an engine provided with an EGR device for returning, as a part of an intake gas flown into the cylinder, an EGR gas, withdrawn from an exhaust passage, to an air intake passage. The amount of oxygen OXM contained in the intake gas and the concentration of oxygen OXC contained in the intake gas are detected (steps S1 and S2). The smoke tolerable limit value QOXMLMT as the upper limit of the amount of fuel injection, which can suppress the amount of smoke generated in the engine to a predetermined tolerance range, is set based on the detected amount of oxygen and concentration of oxygen (step S4), and, when the required amount of injection QDMD determined based on operation conditions is larger than the tolerable limit value QOXMLMT, the instructional injection amount QFIN is limited to the tolerable limit value QOXMLMT.

Claims

1. A fuel injection control device applied to an internal combustion engine having an EGR device for returning, as a part of an intake gas flown into the cylinder, an EGR gas, withdrawn from an exhaust passage, to an intake passage, comprising:

an oxygen amount detection device for detecting the amount of oxygen contained in the intake gas;

a concentration detection device for detecting the concentration of a specific gas contained in the intake gas or a value representing the concentration; and

a smoke tolerable limit value setting device for setting the smoke tolerable limit value as the upper limit of an amount of fuel injection, which can suppress an amount of smoke generated in the engine to a predetermined tolerance range, based on the results detected by the oxygen amount detection device and the concentration detection device,

wherein the concentration detection device detects the concentration of oxygen as the concentration of the specific gas, and the smoke tolerable limit value setting device sets the smoke tolerable limit value on the basis of the detected amount of oxygen and concentration of oxygen, and

wherein the smoke tolerable limit value setting device determines the smoke tolerable limit value corresponding to a predetermined concentration of oxygen on the basis of the amount of oxygen detected by the oxygen amount detection device, corrects the determined smoke tolerable limit value according to the difference between the concentration of oxygen detected by the concentration detection device and the predetermined concentration of oxygen, and sets the corrected smoke tolerable limit value to the smoke tolerable limit value in the final form.

2. The fuel injection control device according to claim 1, wherein the smoke tolerable limit value setting device determines two smoke tolerable limit values corresponding to the amount of oxygen detected by the oxygen amount detection device using map data describing the relation between the amount of oxygen and the smoke tolerable limit values when the concentration of oxygen is controlled at its maximum or its minimum, interpolates the smoke tolerable limit value corresponding to the concentration of oxygen detected by the concentration detection device between the determined two smoke tolerable limit values, and sets the interpolated smoke tolerable limit value to the smoke tolerable limit value in the final form.

3. A fuel injection control device applied to an internal combustion engine having an EGR device for returning, as a part of an intake gas flown into the cylinder, an EGR gas, withdrawn from an exhaust passage, to an intake passage, comprising:

an oxygen amount detection device for detecting the amount of oxygen contained in the intake gas;

a concentration detection device for detecting the concentration of a specific gas contained in the intake gas or a value representing the concentration;

a smoke tolerable limit value setting device for setting the smoke tolerable limit value as the upper limit of an amount of fuel injection, which can suppress an amount of smoke generated in the engine to a predetermined tolerance range, based on the results detected by the oxygen amount detection device and the concentration detection device; and

a fuel injection amount limiting device which compares a required amount of fuel injection determined on the basis of the operating condition of the internal combustion engine with the smoke tolerable limit value determined by the smoke tolerable limit value setting device, and limits the amount of fuel to be introduced into the cylinder to the smoke tolerable limit value when the required amount of fuel injection is larger than the smoke tolerable limit value setting device.