A control portion sets a total injection amount of a urea water injected from an injector to an exhaust gas, and controls to open or close the injector based on the injection amount. An injection-amount correcting portion estimates an injection characteristic of the injector from an injection-amount
A control portion sets a total injection amount of a urea water injected from an injector to an exhaust gas, and controls to open or close the injector based on the injection amount. An injection-amount correcting portion estimates an injection characteristic of the injector from an injection-amount difference between the total injection amount and a decreased amount of the urea water in a tank, and corrects a command value of a control signal outputted to the injector based on the injection characteristic. Therefore, the injection amount is corrected by considering the individual differences or the age-related deterioration.
대표청구항▼
1. A urea-water addition device, comprising: a urea-water tank containing urea water which is an aqueous solution of urea,a urea-water sensor attached to the urea-water tank and detecting an amount of the urea water contained within the urea-water tank,a urea-water injector injecting the urea water
1. A urea-water addition device, comprising: a urea-water tank containing urea water which is an aqueous solution of urea,a urea-water sensor attached to the urea-water tank and detecting an amount of the urea water contained within the urea-water tank,a urea-water injector injecting the urea water received from the urea-water tank into an exhaust gas flowing through an exhaust passage, anda urea-water addition controller electrically connected to the injector and the urea-water sensor and configured to:set an injection amount of the urea water injected from the urea-water injector into the exhaust gas in the exhaust passage, and configured to open or close the urea-water injector based on the injection amount or an adjusted injection amount as defined below,receive a signal from the urea-water sensor detecting an amount of urea water remaining in the urea water tank, to estimate an injection characteristic of the urea-water injector based on a difference between a sum of injection amounts and a decreased amount of the urea water remaining in the urea-water tank computed from the signal of the urea-water sensor, and to adjust the injection amount of the urea-water for injection to the adjusted amount of the urea water based on the injection characteristic,multiply a command value by a correction value corresponding to a reciprocal number of an injection difference (E), andoutput the command value to the injector to control the injection amount. 2. A urea-water addition device according to claim 1, further comprising: a catalyst attached to the exhaust passage, the catalyst promoting a decomposition of nitrogen oxide included in the exhaust gas contained in the exhaust passage,a first NOx sensor connected to an inlet of the catalyst, anda second NOx sensor connected to an outlet of the catalyst, whereinthe urea-water addition controller is configured to terminate adjustment of the injection amount when a concentration of the nitrogen oxide detected by the second NOx sensor is greater than a concentration of the nitrogen oxide detected by the first NOx sensor. 3. A urea-water addition device according to claim 1, wherein the urea-water addition controller is configured to compute the injection difference (E) by dividing the decreased amount (Ld) by the sum (Ct) of injection amounts. 4. A method for correcting a urea-water mixture injector that varies due to either the age of the urea-water mixture injector or manufacturing imperfections of the urea-water mixture injector, comprising: setting a urea-water mixture injector amount via a urea-water addition controller;injecting, via the urea-water addition controller, the urea-water mixture injection amount into an exhaust passage located within an exhaust purification system of a vehicle;determining the actual volume injected into the exhaust passage by measuring, via a urea-water sensor located in a urea-water tank, a decreased amount of a urea-water volume in a urea-water tank,determining the injection difference of the urea-water mixture injection amount and the decreased volume in the urea-water tank; andcorrecting, via the urea-water addition controller, the urea-water mixture injector amount by multiplying the urea-water mixture injector amount by the injection difference and by adjusting the urea-water mixture amount, via the urea-water addition controller, accordingly. 5. A method for correcting a urea-water mixture injector that varies due to either the age of the urea-water mixture injector or manufacturing imperfections of the urea-water mixture injector according to claim 4, further comprising detecting an amount of nitrous oxide via a first nitrous oxide sensor connected to the inlet of a catalyst and a second nitrous oxide sensor connected to the outlet of a catalyst, andterminating the correcting of the urea-water mixture injector amount if a first amount detected by the first nitrous oxide sensor is greater than a second amount detected by the second nitrous oxide sensor.
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이 특허에 인용된 특허 (1)
Kataoka, Ichiro; Ishikawa, Naoto; Aoki, Yoshihito, Heat radiating type liquid level sensing system and the method therefor.
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