JPH03108813U - - Google Patents

Description

[Brief explanation of the drawing]

FIG. 1 is a basic control system diagram of an exhaust gas purification device for an internal combustion engine according to the present invention, FIG. 2 is an equipment control system diagram of an exhaust gas purification device for an internal combustion engine according to an embodiment of the present invention, and FIG.
The figure is a block diagram of the configuration of the engine control computer shown in Figure 2, Figure 4 is a control flow diagram of the fuel injection control routine in the first and second embodiments of the present invention, and Figure 5 is water temperature THW - water temperature increase FWL. Characteristic diagram, Figure 6 shows intake pipe pressure PM - Lean correction coefficient KLEAN PM characteristic diagram, Figure 7 shows engine rotation speed NE - Lean correction coefficient KLEAN
NE characteristic diagram, FIG. 8 is a control flow diagram of the bypass control routine in the first embodiment of the present invention, FIG. 9 is a hysteresis diagram of exhaust temperature TEX-bypass ON/OFF, and FIG. 10 is a lean sensor output LNS
R-bypass ON/OFF hysteresis diagram, Figure 11 shows air-fuel ratio A/F-lean sensor output LNS
Fig. 12 is a hysteresis diagram of throttle opening TA vs. bypass ON/OFF, Fig. 13 is a characteristic diagram of throttle opening TA vs. air-fuel ratio A/F,
Fig. 14 is a control flow diagram of the bypass control routine in the second embodiment of the present invention, and Fig. 15 shows exhaust temperature, air-fuel ratio, throttle opening, bypass ON/O
FIG. 16 is a diagram showing changes in FF over time, and is a characteristic diagram showing the relationship among catalyst durability temperature, NOx purification rate, and air-fuel ratio. 2...Internal combustion engine, 4...Lean NOx catalyst, 6
...Bypass passage, 8...Bypass valve, 10...
Operating state detection means, 12... Catalyst deterioration progression operating state judgment means, 14... Delay means, 18... Lean sensor, 20... Engine control computer, 26... Crank angle sensor, 30... Throttle opening sensor, 32...Intake pipe pressure sensor, 34...Water temperature sensor, 42...Exhaust temperature sensor.

Claims (1)

[Claim for Utility Model Registration] An internal combustion engine equipped with a so-called lean NOx catalyst, which is made of zeolite supported with transition metals or noble metals and reduces NOx in exhaust gas in an oxidizing atmosphere and in the presence of HC. An engine exhaust purification device comprising: a bypass passage that bypasses a lean NOx catalyst; a bypass valve that switches the flow of exhaust gas between the lean NOx catalyst side and the bypass passage; and an operation that detects the operating state of the internal combustion engine. a state detecting means; a catalyst deterioration progressing operating state determining means for determining whether or not the operating state is such that the catalyst deterioration progresses based on an output of the operating state detecting means; A delay means for delaying switching from the bypass passage of the bypass valve to the lean NOx catalyst side for a predetermined period when it is determined that the operating state changes from an operating state that causes catalyst deterioration to an operating state that does not allow catalyst deterioration to progress. Engine exhaust purification device.