TEMPERATURE CONTROL DEVICE OF AIR-FUEL RATIO SENSOR

• Main Author: AMITANI KENJI
• Format: Patent
• Language: English; Japanese
• Published: 06.02.2020
• Subjects: BLASTING; COMBUSTION ENGINES; CONTROLLING COMBUSTION ENGINES; HEATING; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS; INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIRCHEMICAL OR PHYSICAL PROPERTIES; LIGHTING; MEASURING; MECHANICAL ENGINEERING; PHYSICS; TESTING; WEAPONS

To provide a temperature control device for preventing the temperature of a detection element from greatly deviating from a target temperature, during a fine energization duty control for controlling the energization duty of a heater of an air-fuel ratio sensor so that the temperature of the detection element of the air-fuel ratio sensor becomes a target temperature lower than an activation temperature.SOLUTION: A temperature control device includes: an exhaust temperature sensor; an air-fuel ratio sensor having a detection element and a heater; and an ECU (electronic control device). When the ECU executes "fine energization duty control" of controlling the energization duty of the heater so that the temperature (=element temperature Ta/f) of the detection element becomes a fine energization target temperature lower than the target activation temperature, an element temperature Ta/f is calculated using a heat model formula. This heat model formula defines the relationship among a heat-receiving amount Q received by the detection element from the exhaust gas, a heat transfer coefficient α between the exhaust gas and the detection element, an exhaust temperature Tgas, and a detection element temperature Ta/f.SELECTED DRAWING: Figure 8 【課題】空燃比センサの検出素子の温度が活性温度よりも低い目標温度となるように空燃比センサのヒータの通電デューティを制御する微通電デューティ制御中において、検出素子の温度が目標温度から大きく乖離することを防止する温度制御装置を提供する。【解決手段】温度制御装置は、排気温センサと、検出素子とヒータとを含む空燃比センサと、ＥＣＵ（電子制御装置）とを備える。ＥＣＵは、検出素子の温度（＝素子温度Ｔａ／ｆ）が目標活性温度よりも低い微通電目標温度となるようにヒータの通電デューティを制御する「微通電デューティ制御」を実行する際、素子温度Ｔａ／ｆを熱モデル式を用いて算出する。この熱モデル式は、排気から検出素子が受ける受熱量Ｑと、排気と検出素子との間の熱伝達率αと、排気温度Ｔｇａｓと、検出素子温度Ｔａ／ｆとの関係を規定した式である。【選択図】図８