Control apparatus for an engine

Patent metadata

Field	Value
Publication number	US-9617943-B2
Application number	US-201313848999-A
Country	US
Kind code	B2
Filing date	Mar 22, 2013
Priority date	Jun 29, 2012
Publication date	Apr 11, 2017
Grant date	Apr 11, 2017

Abstract

A control apparatus for an engine introduces purge gas containing fuel gas evaporated from a fuel tank into an intake system includes an air-fuel ratio calculation unit that calculates an air-fuel ratio (AF) of the engine, and a purge rate calculation unit that calculates a purge rate (R PRG ) corresponding to an introduction rate of the purge gas. The control apparatus further includes a concentration calculation unit that calculates a concentration (K AF _ PRG ) of the purge gas based on the air-fuel ratio (AF) calculated by the air-fuel ratio calculation unit and the purge rate (R PRG ) calculated by the purge rate calculation unit. A decision unit permits or inhibits the concentration calculation unit to calculate the concentration (K AF _ PRG ) based on the purge rate (R PRG ) calculated by the purge rate calculation unit. The estimation accuracy of the concentration (K AF _ PRG ) of purge gas is improved.

First claim

The invention claimed is:

1. A control apparatus for an engine having a purge control valve that controls a flow rate of purge gas containing fuel gas evaporated from a fuel tank introduced into an intake system, comprising:
an air-fuel ratio calculation unit that calculates an air-fuel ratio (AF) of the engine;
a purge rate calculation unit that calculates a purge rate (R PRG ) corresponding to an introduction rate of the purge gas;
a concentration calculation unit that calculates a concentration (K AF _ PRG ) of the purge gas based on the air-fuel ratio (AF) calculated by the air-fuel ratio calculation unit and the purge rate (R PRG ) calculated by the purge rate calculation unit;
a decision unit that permits or inhibits the concentration calculation unit to calculate the concentration (K AF _ PRG ) based on the purge rate (R PRG ) calculated by the purge rate calculation unit;
an air amount calculation unit that calculates an air amount (E C ) to be introduced into a cylinder of the engine;
an inhibition period calculation unit that calculates a criterion influence time period for which the calculation of the concentration (K AF _ PRG ) by the concentration calculation unit is inhibited based on the air amount (E C ) calculated by the air amount calculation unit, the criterion influence time period being set shorter as the air amount (Ec) is greater; and
a control unit that controls the purge control valve based on the concentration (K AF _ PRG ) such that the air-fuel ratio (AF) calculated by the air-fuel ratio calculation unit becomes a target air-fuel ratio,
wherein the decision unit permits the concentration calculation unit to calculate the concentration (K AF _ PRG ) only when the criterion influence time period elapses after predetermined driving conditions for permitting the calculation of the concentration (K A _ PRG ) are met, and
wherein
the inhibition period calculation unit converts the criterion influence time period into a stroke number (IG) for every combustion cycle,
the inhibition period calculation unit calculates a reciprocal number (1/IG) of the stroke number, the reciprocal number (1/IG) being defined as a fraction, a numerator of the fraction being set to 1 and a denominator of the fraction being set to the stroke number (IG),
the inhibition period calculation unit calculates an integrated value (C) by adding the reciprocal number (1/IG) in every combustion cycle, and
the inhibition period calculation unit decides that the criterion influence time period of the purge gas has elapsed when the integrated value (C) becomes equal to or higher than 1.0.

2. The control apparatus according to claim 1 , wherein
the decision unit allows the concentration calculation unit to update a calculation value of the concentration (K AF _ PRG ) to the latest value when the purge rate (R PRG ) is equal to or higher than a criterion rate (R TH ); and
the decision unit makes the concentration calculation unit maintain the last value of the concentration (K AF _ PRG ) when the purge rate (R PRG ) is lower than the criterion rate (R TH ).

3. The control apparatus according to claim 1 , wherein
the decision unit permits or inhibits the calculation of the concentration (K AF _ PRG ) to the concentration calculation unit based on a fuel amount correction coefficient (K FB _ PRG ) correlative to a difference between the air-fuel ratio (AF) calculated by the air-fuel ratio calculation unit and a target air-fuel ratio.

4. The control apparatus according to claim 2 , wherein
the decision unit permits or inhibits the calculation of the concentration (K AF _ PRG ) to the concentration calculation unit based on a fuel amount correction coefficient (K FB _ PRG ) correlative to a difference between the air-fuel ratio (AF) calculated by the air-fuel ratio calculation unit and a target air-fuel ratio.

5. The control apparatus according to claim 3 , wherein
the decision unit
inhibits the calculation of the concentration (K AF _ PRG ) in a driving state in which the variation amount of the fuel amount correction coefficient (K FB _ PRG ) is equal to or greater than a criterion amount, and
permits the calculation of the concentration (K AF _ PRG ) in another driving state in which the variation amount of the fuel amount correction coefficient (K FB _ PRG ) is smaller than the criterion amount.

6. The control apparatus according to claim 4 , wherein
the decision unit
inhibits the calculation of the concentration (K AF _ PRG ) in a driving state in which the variation amount of the fuel amount correction coefficient (K FB _ PRG ) is equal to or greater than a criterion amount, and
permits the calculation of the concentration (K AF _ PRG ) in another driving state in which the variation amount of the fuel amount correction coefficient (K FB _ PRG ) is smaller than the criterion amount.

7. The control apparatus according to claim 1 , wherein
the decision unit
inhibits the calculation of the concentration (K AF _ PRG ) when, among the predetermined driving conditions, the engine is accelerated or decelerated suddenly, and
permits the calculation of the concentration (K AF _ PRG ) except a case in which the engine is accelerated or decelerated suddenly.

8. The control apparatus according to claim 1 , wherein
the decision unit
inhibits the calculation of the concentration (K AF _ PRG ) when, among the predetermined driving conditions, a load acting on the engine is equal to or lower than a criterion amount, and
permits the calculation of the concentration (K AF _ PRG ) when the load is higher than the criterion amount.

9. The control apparatus according to claim 1 , wherein
the decision unit
permits the calculation of the concentration (K AF _ PRG ) when, among the predetermined driving conditions, feedback injection control is being carried out, and
inhibits the calculation of the concentration (K AF _ PRG ) when open loop injection control is being carried out.

10. The control apparatus according to claim 1 , wherein
the decision unit changes a condition for permitting or inhibiting the calculation of the concentration (K AF _ PRG ) in response to the air-fuel ratio (AF).

11. The control apparatus according to claim 1 , further comprising:
an air-fuel ratio sensor disposed downstream from an exhaust manifold of the engine,
wherein the criterion influence time period corresponds to a time required before the purge gas passing the purge control valve arrives at a proximity of the air-fuel ratio sensor.

Assignees

• Mitsubishi Motors Corp

Inventors

• Ide Hideto
• Ueda Katsunori
• Miyata Toshiyuki

Classifications

• F02D41/0042

  Controlling the combustible mixture as a function of the canister purging, e.g. control of injected fuel to compensate for deviation of air fuel ratio when purging · CPC title

• F02D41/3005 Primary

  Details not otherwise provided for · CPC title

• F02D41/1454 Primary

  the characteristics being an oxygen content or concentration or the air-fuel ratio · CPC title

• F02D41/0045

  Estimating, calculating or determining the purging rate, amount, flow or concentration · CPC title