CATALYST WARMING-UP CONTROL DEVICE

• US 20090308059A1
• Filed: 06/15/2009
• Published: 12/17/2009
• Est. Priority Date: 06/17/2008
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Ikemoto, Noriaki
• Granted Patent: US 8,205,438 B2
• Time in Patent Office: Days
• US Class Current: 60/287
• CPC Class Codes: F01N 3/043 without contact between liquid and exhaust gases
• CPC Class Codes: F01N 5/02 the devices using heat
• CPC Class Codes: F01N 9/00 Electrical control of exhaust gas treating apparatus monitoring or diagnostic devices for exhaust-gas treatment apparatus F01N11/00; conjoint electrical control of two or more combustion engine functions F02D43/00
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A catalyst is provided in an exhaust passage of an engine and an evaporating section of a heat recovery device is provided upstream of the catalyst in the exhaust passage. An ECU performs an operation for compulsorily oscillating an air-fuel ratio between a lean state and a rich state as compared to a theoretical air-fuel ratio when temperature of the catalyst reaches temperature at which the catalyst has a predetermined purification capacity after the engine is started. The ECU restricts a flow of a working fluid in the heat recovery device until the temperature of the catalyst reaches the temperature at which the catalyst has the predetermined purification capacity after the engine is started.

Claims

1. A warming-up control device of a catalyst applied to an engine system having a heat recovery device that circulates a working fluid through a predetermined circulation passage and that recovers exhaust gas heat via the working fluid at the same position as the catalyst or upstream of the catalyst in an exhaust passage of an engine, the heat recovery device radiating the recovered heat to a temperature increase object, the warming-up control device comprising:

a determination means for determining whether a state where the catalyst enables a predetermined purification reaction is reached in the process of activation of the catalyst;

a first control means for starting control for promoting a reaction in the catalyst and for increasing catalytic reaction heat when it is determined that the state where the predetermined purification reaction is enabled is reached; and

a second control means for restricting the flow of the working fluid in the heat recovery device to reduce heat recovery amount as compared to a case where the recovery of the exhaust gas heat is performed to raise the temperature of the temperature increase object to a predetermined temperature at least while it is determined that the state where the predetermined purification reaction is enabled is not reached.

2. The warming-up control device as in claim 1, wherein

at least while it is determined that the state where the predetermined purification reaction is enabled is not reached, the second control means restricts the flow of the working fluid while controlling the flow rate of the working fluid such that temperature or pressure of the working fluid at a heat recovery point in the circulation passage becomes equal to or lower than a limit value set in accordance with strength of the circulation passage at the heat recovery point.

3. The warming-up control device as in claim 2, wherein

the second control means stops the flow of the working fluid when the temperature or the pressure of the working fluid at the heat recovery point is equal to or lower than the limit value in a state where the flow of the working fluid is restricted.

4. The warming-up control device as in claim 2, wherein

the second control means starts control of the flow rate for conforming the temperature or the pressure of the working fluid at the heat recovery point to a predetermined target value lower than the limit value when it is determined that the state where the predetermined purification reaction is enabled is reached or in a period after it is determined that the state is reached and before the catalyst reaches an activated state.

5. The warming-up control device as in claim 1, wherein

the second control means stops the flow of the working fluid at least while it is determined that the state where the predetermined purification reaction is enabled is not reached.

6. The warming-up control device as in claim 1, wherein

the second control means switches from a state where the flow of the working fluid is restricted to a state where the flow of the working fluid is not restricted when it is determined that the state where the predetermined purification reaction is enabled is reached or in a period after it is determined that the state is reached and before the catalyst reaches an activated state.

7. The warming-up control device as in claim 6, wherein

the second control means switches from a state where the flow of the working fluid is restricted to a state where the flow of the working fluid is not restricted at timing after the first control means switches from a state before the reaction in the catalyst is promoted to a state where the reaction in the catalyst is promoted.

8. The warming-up control device as in claim 1, further comprising:

a third control means for raising the temperature of the exhaust gas at least while it is determined that the state where the predetermined purification reaction is enabled is not reached.

9. The warming-up control device as in claim 1 wherein

the determination means performs the determination based on at least one of a difference between an oxygen concentration upstream of the catalyst and an oxygen concentration downstream of the catalyst, an estimate of the temperature of the catalyst estimated using an integration value of the temperature of the exhaust gas supplied to the catalyst and a flow rate of the exhaust gas and an actual measurement value of the temperature of the catalyst.