(19)
(11) EP 0 837 237 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
28.04.1999 Bulletin 1999/17

(43) Date of publication A2:
22.04.1998 Bulletin 1998/17

(21) Application number: 97117882.7

(22) Date of filing: 15.10.1997
(51) International Patent Classification (IPC)6: F02M 25/07
(84) Designated Contracting States:
AT BE CH DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE
Designated Extension States:
AL LT LV RO SI

(30) Priority: 16.10.1996 JP 273402/96

(71) Applicant: TOYOTA JIDOSHA KABUSHIKI KAISHA
Aichi (JP)

(72) Inventor:
  • Demura, Takayuki
    Toyota-shi, Aichi (JP)

(74) Representative: Pellmann, Hans-Bernd, Dipl.-Ing. et al
Patentanwaltsbüro Tiedtke-Bühling-Kinne & Partner Bavariaring 4
80336 München
80336 München (DE)

   


(54) Exhaust gas recirculation system for internal combustion engine and method for detecting an abnormal condition thereof


(57) An exhaust gas recirculation (EGR) system for an internal combustion engine is capable of correctly determining whether or not an EGR control valve (9) is sound, irrespective of variations in the characteristics of a unit for setting a negative pressure applied to the EGR control valve or the aging of the unit.
The EGR system has the EGR control valve (9) disposed in a recirculation path (8) that connects an exhaust path (2) to an intake path (3) of the engine (1), for controlling the flow rate of exhaust gas recirculated through the recirculation path (8), an aperture detector for detecting a real aperture of the EGR control valve (9) at proper intervals, a driver for driving the EGR control valve (9) in a way to provide a target aperture that is set at proper intervals according to operating conditions of the engine (1), and a diagnostic unit that determines that the EGR system including the EGR control valve (9) is abnormal if real apertures detected by the aperture detector do not follow corresponding target apertures after the target apertures show a change of predetermined magnitude.






Search report