Search

JP-7855929-B2 - Engine diagnostic methods and engine systems

JP7855929B2JP 7855929 B2JP7855929 B2JP 7855929B2JP-7855929-B2

Inventors

  • 大西 毅
  • ▲高▼木 健太郎
  • 岡田 茂美
  • 松本 忠大
  • 吉田 壮太郎
  • 岡部 龍之介

Assignees

  • マツダ株式会社

Dates

Publication Date
20260511
Application Date
20220603

Claims (6)

  1. A method for diagnosing an engine comprising: a cylinder; a piston that reciprocates within the cylinder; an intake passage communicating with the cylinder; an intake valve that opens and closes the communication between the cylinder and the intake passage by reciprocating; an exhaust passage communicating with the cylinder; a particulate filter provided downstream of the exhaust passage; an EGR device that recirculates exhaust gas from the exhaust passage upstream of the particulate filter into the intake passage; an intake flow rate detection unit that detects the airflow rate through the intake passage; and a controller to which the detection information from the intake flow rate detection unit is input , wherein The controller includes a valve operation determination step in which it determines that a malfunction of the intake valve has occurred, provided that the determination index calculated from the intake flow rate detection unit detected by the intake flow rate detection unit is less than a predetermined determination threshold , An engine diagnostic method comprising: when the intake valve is functioning normally and there is no failure to close, the valve operation determination step is not performed when the determination index is below a predetermined rotational speed that is below a predetermined determination threshold; and the valve operation determination step is performed when the rotational speed is above the predetermined speed .
  2. The intake air flow rate detection unit is characterized by being an airflow sensor provided in the intake passage. The method for diagnosing an engine according to claim 1.
  3. The aforementioned judgment indicators are, The method for diagnosing an engine according to claim 1 or claim 2, wherein the average value calculated from a plurality of intake flow detection values that change in response to changes in piston speed during the intake stroke detected by the intake flow detection unit is divided by the minimum intake flow value during the intake stroke calculated by the intake flow detection unit.
  4. An engine comprising: a cylinder; a piston that reciprocates within the cylinder; an intake passage communicating with the cylinder; an intake valve that opens and closes the communication between the cylinder and the intake passage by reciprocating; an intake flow rate detection unit that detects the intake air flow rate that flows through the intake passage into the cylinder when the intake valve is open; an exhaust passage communicating with the cylinder; a particulate filter provided in the exhaust passage downstream of the exhaust passage; and an EGR device that recirculates exhaust gas from the exhaust passage upstream of the particulate filter into the intake passage . The system includes a controller electrically connected to the intake airflow detection unit, configured to determine that a malfunction of the intake valve has occurred , provided that a determination index calculated from the intake airflow detection value received from the intake airflow detection unit is less than a predetermined determination threshold , The controller is characterized in that, when there is no failure to close the intake valve, the determination is not made when the rotational speed is below a predetermined rotational speed at which the determination index falls below a predetermined determination threshold, and the determination is made when the rotational speed is above the predetermined rotational speed .
  5. The intake air flow rate detection unit is an airflow sensor located upstream of the intake passage. The engine system according to claim 4 .
  6. The controller is further configured to use as a determination index a value obtained by dividing the average value calculated from a plurality of detected values that change in response to the change in piston speed during the intake stroke , received from the intake flow rate detection unit, by the minimum intake flow rate detected value during the intake stroke, received from the intake flow rate detection unit . The engine system according to claim 4 or claim 5 .

Description

Applicable under Article 30, Paragraph 2 of the Patent Law. Sales began on September 28, 2021, at dealerships handling Mazda vehicles in Europe. This invention relates to a technology for detecting abnormal operation of intake valves in an engine. In engines, deposits adhering to the intake passage can detach and flow towards the combustion chamber, sometimes becoming lodged between the intake valve and valve seat. This lodging can cause the intake valve to fail to close properly, leading to compression leaks. Compression leaks prevent the cylinder temperature from rising sufficiently during the compression stroke, potentially leading to ignition failures in diesel engines. Therefore, it is necessary to detect intake valve closure failures caused by deposit lodging. Patent Document 1 discloses a method for detecting intake valve closure failure due to deposit buildup based on crank angular velocity information from a crank angle sensor. The technology disclosed in Patent Document 1 detects intake valve closure failure due to deposit buildup based on crank angular velocity information from various crank sensors during vehicle deceleration fuel cut-off. The crank angular velocity information is used to detect intake valve closure failure due to deposit buildup by comparing the ratio of the passage times (T5/T7) calculated from the passage time T5 of a 30°CA section centered on top dead center of compression and the passage time T7 of a 30°CA section in the subsequent expansion stroke with a threshold value. Japanese Patent Publication No. 2018-184887 This is a system diagram showing the overall configuration of an engine to which a control device according to one embodiment of the present invention is applied.This is a cross-sectional view showing details of the intake and exhaust valves and their valve train mechanism.This is a schematic plan view showing the structure of the power transmission system between the engine and the wheels.This is a functional block diagram showing the control systems for the engine and automatic transmission.(a) is the intake airflow detection value af, and (b) is a time chart showing a magnified portion of (a).This flowchart shows the control methods used by PMC to diagnose intake valve closure failures.Figure 6 is a flowchart detailing the control steps in step S3.(a) is a time chart showing the minimum value af_min, (b) is the average value af_mav, and (c) is a time chart showing the judgment index ind_diag and judgment threshold ind_fail.Figure 7 is a flowchart showing the details of the engine speed mask in the mask flag of step S31.Figure 7 is a flowchart showing the details of the intake shutter opening mask in the mask flag of step S31.This flowchart shows the details of the startup mask in the mask flag of step S31 in Figure 7.Figure 7 is a flowchart showing the details of the EGR valve opening mask in the mask flag of step S31. Figure 1 is a system diagram showing the overall configuration of an engine to which a control device according to one embodiment of the present invention is applied. The engine 1 shown in this figure is a four-stroke diesel engine mounted in a vehicle as a power source for driving. The engine 1 comprises an engine body 2, an intake passage 30 through which intake air introduced into the engine body 2 flows, an exhaust passage 40 through which exhaust gas discharged from the engine body 2 flows, an EGR device 50 that recirculates a portion of the exhaust gas flowing through the exhaust passage 40 back into the intake passage 30, and a supercharger 60 that supercharges the intake air flowing through the intake passage 30. The engine body 2 is a multi-cylinder type having multiple cylinders 2a arranged in a direction perpendicular to the plane of the paper in Figure 1 (see also Figure 3, described later). The engine body 2 comprises a cylinder block 3, a cylinder head 4, and multiple pistons 5. Each cylinder 2a is formed by the cylinder block 3 and the cylinder head 4. That is, multiple cylindrical spaces corresponding to the multiple cylinders 2a are formed inside the cylinder block 3, and the cylinder head 4 is mounted on the upper surface of the cylinder block 3 so as to close these cylindrical spaces from above. The pistons 5 are housed in each cylinder 2a so as to be able to reciprocate and slide. In this embodiment, the side from the cylinder block 3 toward the cylinder head 4 is treated as the top, and the opposite side as the bottom; however, this is for the sake of explanation and is not intended to limit the mounting orientation of the engine body 2. A combustion chamber C is formed above the piston 5 of each cylinder 2a. Each combustion chamber C is a space defined by the lower surface of the cylinder head 4, the side surface of the cylinder 2a (cylinder liner), and the upper surface (crown surface) of the piston 5. The combustion chamber C receives fuel supplied from a fuel injection valve 9, which will be described later. The piston 5