Method to limit temperature increase in a catalyst and detect a restricted exhaust path in a vehicle

Patent metadata

Field	Value
Publication number	US-9527498-B2
Application number	US-201213597907-A
Country	US
Kind code	B2
Filing date	Aug 29, 2012
Priority date	Aug 29, 2012
Publication date	Dec 27, 2016
Grant date	Dec 27, 2016

Abstract

A vehicle has an engine, an exhaust aftertreatment system, an electric machine, and a controller configured to, in response to an actual engine torque output being less than an inferred engine torque, shut down the engine. A vehicle has an engine, an exhaust aftertreatment system, an electric machine, and a controller configured to, in response to an actual engine torque output being less than a first threshold and a torque request to the engine being greater than a second threshold, set a diagnostic code. A method includes receiving an actual engine torque output, receiving an engine torque request, and shutting down the engine when the actual engine torque output is less than a first threshold and the engine torque request is greater than a second threshold for a predetermined time period to limit temperature increase of a catalyst.

First claim

What is claimed is:

1. A vehicle comprising:
an engine connected to an electric motor; and
a controller configured to shut down the engine to limit an exhaust catalyst temperature increase when actual engine torque output is less than (i) expected engine torque output (τ) for a predetermined time period including successive cylinder combustion cycles, and (ii) a threshold (T 1 ), desensitized with decreasing engine coolant temperature (ECT), T 1 a function of τ and ECT, wherein desensitizing T 1 comprises lowering T 1 .

2. The vehicle of claim 1 wherein the predetermined time period is a first predetermined time period, and wherein T 1 is a first threshold;
wherein the controller is configured to, in response to the actual engine Torque output being less than the first threshold for the predetermined time period, shut down the engine to limit temperature increase of the catalyst; and
wherein the controller is further configured to, in response to the actual engine torque output being less than a second threshold and a requested engine torque output being greater than a third threshold for a second predetermined time period, shut down the engine to limit temperature increase of the catalyst, the second predetermined time period being greater than the first predetermined time period.

3. The vehicle of claim 1 wherein τ is based on fuel flow and air flow to the engine, spark retard in the engine, and a speed of the engine.

4. The vehicle of claim 1 wherein the controller is further configured to increment a stall counter in response to the actual engine torque output being less than τ for the predetermined time period and to compare the stall counter to a maximum value before shutting down the engine, the maximum value being set based on a catalyst temperature.

5. The vehicle of claim 4 wherein the controller is further configured to, in response to the stall counter being less than the maximum value, restart the combustion process in the engine.

6. The vehicle of claim 4 wherein the maximum value is further set based on a start condition of the engine.

7. The vehicle of claim 1 wherein the controller is further configured to shut down the engine in response to satisfying an entry condition based on an engine state.

8. The vehicle of claim 7 wherein the entry condition is unsatisfied if one of spark retard above a predetermined level, a disabled fuel injector and operating in secondary idle is present.

9. The vehicle of claim 1 wherein the controller is configured to determine T 1 using τ and ECT as inputs into a calibration table.

10. The vehicle of claim 1 wherein the controller is configured to, in response to the actual engine torque output being less than τ for the predetermined time period and less than T 1 , and the engine being rotated by the electric motor, shut down the engine to limit temperature increase of the catalyst.

11. The vehicle of claim 1 further comprising a secondary power source to propel the vehicle, the secondary power source including the electric motor.

12. The vehicle of claim 1 further comprising a transmission including a planetary gear unit, wherein the engine, the electric motor, and torque transfer gearing are connected to the planetary gear unit, the torque transfer gearing drivably connected to a vehicle wheel.

13. The vehicle of claim 6 wherein the maximum value of the stall counter is set based on a criteria, the criteria comprising: (i) engine start with a catalyst temperature below a first temperature threshold, (ii) engine start with a catalyst temperature above a second temperature threshold, (iii) engine stall with the catalyst temperature below the first temperature threshold, and (iv) engine stall with the catalyst temperature above the second temperature threshold, wherein each stall criteria has an associated maximum count value.

Assignees

• Martin Douglas Raymond
• Treharne William David
• Smith Matthew D
• Ford Global Tech Llc

Inventors

• Martin Douglas Raymond
• Treharne William David
• Smith Matthew D

Classifications

• F02D29/02

  peculiar to engines driving vehicles; peculiar to engines driving variable pitch propellers · CPC title

• B60W20/16

  for reducing engine exhaust emissions · CPC title

• F02D17/04

  rendering engines inoperative or idling, e.g. caused by abnormal conditions (dependent on lubricating conditions F01M1/22; dependent on cooling F01P5/14) · CPC title

• F02D2200/1004

  Estimation of the output torque · CPC title

• B60W2710/0694

  Engine exhaust temperature · CPC title