Error diagnosis device and error diagnosis method

Patent metadata

Field	Value
Publication number	US-11242815-B2
Application number	US-201917040350-A
Country	US
Kind code	B2
Filing date	Mar 20, 2019
Priority date	Mar 22, 2018
Publication date	Feb 8, 2022
Grant date	Feb 8, 2022

Abstract

The error diagnosis device has: an input unit that receives detected values for pressure inside the common rail; a calculation unit that, if the detected values are less than a target common rail pressure, calculates the pressure differences and the fuel pump discharge amounts; and a determination unit that determines whether or not a set time has lapsed in a state in which the pressure differences are at least a first threshold value and less than a second threshold value and the discharge amounts are at least a third threshold value and less than a fourth threshold value. The determination unit determines that an error has occurred in the high-pressure pump if the set time has lapsed and determines that an error has occurred in the flowrate adjustment valve if the set time has not lapsed.

First claim

The invention claimed is:

1. A malfunction diagnosis device for diagnosing a malfunction of a fuel pump that includes a flow control valve for adjusting a flow rate of fuel pumped up from a storage section, and a high pressure pump for pressurizing the fuel whose flow rate is adjusted and discharging the fuel to a pressure accumulator section, the malfunction diagnosis device comprising:
an input section that receives a detected value of a pressure of the fuel in the pressure accumulator section;
a calculation section that calculates, when the detected value is less than a target value of the pressure, a differential pressure between the target value and the detected value, and a discharge amount of the fuel discharged from the fuel pump; and
a determination section that determines whether a preset time has passed in a state where the differential pressure is equal to or more than a first threshold value and less than a second threshold value while the discharge amount is equal to or more than a third threshold value and less than a fourth threshold value,
wherein the determination section determines that:
a malfunction has occurred at the high pressure pump, when the preset time passes, and
a malfunction has occurred at the flow control valve, when the preset time does not pass, and

wherein the first threshold value is an upper limit value of the differential pressure when all of plungers provided in the high pressure pump operate normally;
the second threshold value is an upper limit value of the differential pressure when at least one of the plungers operates normally and at least one of the plungers is broken;
the third threshold value is a lower limit of a maximum dischargeable amount of the high pressure pump when at least one of the plungers operates normally and at least one of the plungers is broken; and
the fourth threshold value is a lower limit of a maximum dischargeable amount of the high pressure pump when all of the plungers operate normally.

2. The malfunction diagnosis device according to claim 1 , wherein:
the calculation section calculates the discharge amount based on a target injection amount of an injector that injects the fuel supplied from the pressure accumulator section, and a rotation speed of an internal combustion engine.

3. A method for diagnosing a malfunction of a fuel pump that includes a flow control valve for adjusting a flow rate of fuel pumped up from a storage section, and a high pressure pump for pressurizing the fuel whose flow rate is adjusted and discharging the fuel to a pressure accumulator section, the method comprising:
receiving a detected value of a pressure of the fuel in the pressure accumulator section;
calculating, when the detected value is less than a target value of the pressure, a differential pressure between the target value and the detected value, and a discharge amount of the fuel from the fuel pump;
determining whether a preset time has passed in a state where the differential pressure is equal to or more than a first threshold value and less than a second threshold value while the discharge amount is equal to or more than a third threshold value and less than a fourth threshold value; and
determining that a malfunction has occurred at the high pressure pump, when the preset time passes, and determining that a malfunction has occurred at the flow control valve, when the preset time does not pass,
wherein the first threshold value is an upper limit value of the differential pressure when all of plungers provided in the high pressure pump operate normally;
the second threshold value is an upper limit value of the differential pressure when at least one of the plungers operates normally and at least one of the plungers is broken;
the third threshold value is a lower limit of a maximum dischargeable amount of the high pressure pump when at least one of the plungers operates normally and at least one of the plungers is broken; and
the fourth threshold value is a lower limit of a maximum dischargeable amount of the high pressure pump when all of the plungers operate normally.

Assignees

• Isuzu Motors Ltd

Inventors

• Kobayashi Yuusuke
• Shidomi Katsushi
• Noda Kunio
• Ishii Daiki
• Okazaki Fumihiko

Classifications

• F02D41/40

  with means for controlling injection timing or duration · CPC title

• F02D2041/224

  Diagnosis of the fuel system · CPC title

• F02D41/22 Primary

  Safety or indicating devices for abnormal conditions {(in air/fuel ratio feedback systems F02D41/1495, in electric control linkage F02D11/107, in purge control systems F02M25/0809)} · CPC title

• F02D1/02

  not restricted to adjustment of injection timing, e.g. varying amount of fuel delivered · CPC title

• F02M59/44 Primary

  Details, components parts, or accessories not provided for in, or of interest apart from, the apparatus of groups F02M59/02 - F02M59/42; {Pumps having transducers, e.g. to measure displacement of pump rack or piston} · CPC title