JP-2026075358-A - Method for estimating the degree of deposit accumulation in the intake system

Abstract

[Problem] To facilitate confirmation of the degree of deposit accumulation in the intake system. [Solution] The amount of fine particles flowing into the intake system along with the outside air is calculated from the change in mass of the element 13 of the air cleaner 12, the amount of oil mist flowing into the intake system along with blow-by gas is calculated from the operating state of the engine 10, and the frequency of the temperature conditions for oxidation of the oil mist is calculated from the intake air temperature. Based on these calculation results, the degree of deposit accumulation in the intake system of the engine 10 is estimated. [Selection Diagram] Figure 1

Inventors

• 宮田　久嗣

Assignees

• トヨタ自動車株式会社

Dates

Publication Date

20260508

Application Date

20241022

Claims (1)

1. A method for estimating the degree of deposit accumulation in an engine's intake system, comprising: the amount of fine particles flowing into the intake system with outside air; the amount of oil mist recirculated into the intake system with blow-by gas; and the frequency with which the temperature conditions for oxidation of the oil mist occur.

Description

This invention relates to a method for estimating the degree of deposit accumulation in an engine's intake system. Patent Document 1 describes how, when the amount of intake air predicted from the engine's rotational speed and throttle opening is less than the actual amount of intake air, it can be determined that the intake air passage area of the intake port has decreased due to deposit accumulation. Japanese Patent Publication No. 2006-194153 This diagram schematically shows the configuration of the intake system of an engine used to estimate the degree of intake system deposit accumulation.This diagram shows the diagnostic process for deposit accumulation in the intake system. Hereinafter, with reference to Figures 1 and 2, one embodiment of a method for estimating the degree of deposit accumulation in the intake system will be described in detail. <Engine intake system configuration> First, referring to Figure 1, the configuration of the intake system of the engine 10, where the intake system deposits targeted for estimation of the degree of deposit accumulation in this embodiment are deposited, will be explained. An air cleaner 12 is provided in the intake passage 11 of the engine 10 shown in Figure 1. Inside the air cleaner 12, an element 13 is installed to capture fine particles in the outside air drawn into the intake passage 11. A throttle valve 14 is installed in the intake passage 11 downstream of the air cleaner 12, and a surge tank 15 is installed further downstream. Downstream of the surge tank 15 in the intake passage 11, two passages merge: an EGR passage 16 for recirculating exhaust gas into the intake air flowing through the intake passage 11, and a PCV passage 17 for recirculating blow-by gas. Furthermore, an injector 18 for injecting fuel into the intake air is connected to the intake passage 11 downstream of the confluence of the EGR passage 16 and the PCV passage 17. The intake passage 11 is connected to the combustion chamber 20 via the intake valve 19. The engine 10 is controlled by an electronic control unit 21. Various sensors are connected to the electronic control unit 21, and based on the detection results of these sensors, it acquires state variables indicating the operating state of the engine 10, such as engine rotational speed Ne, engine load ratio Kl, and intake air temperature Tha. The electronic control unit 21 records these state variables while the engine 10 is running. During vehicle inspections at dealerships, etc., the electronic control unit 21 is connected to an external diagnostic device 22, which is a computer terminal for external vehicle diagnostics. <Method for estimating the degree of deposit accumulation in the intake system> Deposits accumulating in the intake system of engine 10 can cause problems such as seizing of moving parts and blockage of piping. Examples of areas where deposit accumulation in the intake system can be problematic include the following areas A to F. Area A is the area near the throttle valve 14 in the intake passage 11. Area B is the inside of the surge tank 15. Area C is the junction of the EGR passage 16 with the intake passage 11. Area D is the junction of the PCV passage 17 with the intake passage 11. Area E is the area near the injector 18 in the intake passage 11. Area F is the area near the intake valve 19 in the intake passage 11. Directly confirming the accumulation of intake system deposits in parts A to F requires disassembly of the intake system components. Therefore, the degree of intake system deposit accumulation in parts A to F is generally estimated based on the vehicle's total mileage and years of use. However, the degree of intake system deposit accumulation varies significantly depending on the operating environment of the engine 10 and the user's usage. This embodiment presents a method for estimating the degree of intake system deposit accumulation with sufficient accuracy without direct inspection. Intake system deposits include those originating from fine particles flowing into the intake passage 11 along with outside air, and those originating from oil mist contained in blow-by gas recirculated into the intake air through the PCV passage 17. In the following explanation, the former intake system deposits will be referred to as outside air-derived deposits, and the latter as oil-derived deposits. Of the fine particles drawn into the air cleaner 12 along with the outside air, those with a particle size above a certain level are captured by the element 13, while the remaining particles pass through the element 13. These particles that pass through the element 13 are the cause of the outside air-derived deposits. The ratio of particles that pass through the element 13 to reach each of the intake system parts A to F and accumulate as outside air-derived deposits can be determined in advance through experiments. Furthermore, the particle size distribution of airborne particles can be measured in advance. From the p