Method and system for exhaust heat exchanger diagnostics

• US 10,487,782 B2
• Filed: 03/06/2018
• Issued: 11/26/2019
• Est. Priority Date: 10/18/2016
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Bevan, Karen Evelyn, Pursifull, Ross Dykstra, Uhrich, Michael James, Ulrey, Joseph Norman
• Primary Examiner(s): Moulis, Thomas N
• Application Number:
  US15/913,554
• Publication Number:
  US 20180195470A1
• Time in Patent Office: 630 Days
• CPC Class Codes: B60H 1/00314 Arrangements permitting a rapid heating of the heating liquid B60H1/00492, B60H1/03 take precedence; aiding engine start by heating of engine coolants F02N19/10
• CPC Class Codes: B60H 1/00978 Control systems or circuits characterised by failure of detection or safety means; Diagnostic methods
• CPC Class Codes: B60H 1/025 from both the cooling liquid and the exhaust gases of the propulsion plant
• CPC Class Codes: F01N 11/002 the diagnostic devices measuring or estimating temperature or pressure in, or downstream of the exhaust apparatus
• CPC Class Codes: F01N 2240/02 a heat exchanger
• CPC Class Codes: F01N 2240/22 a condensation chamber
• CPC Class Codes: F01N 2410/00 By-passing, at least partially, exhaust from inlet to outlet of apparatus, to atmosphere or to other device
• CPC Class Codes: F01N 2560/06 the means being a temperature sensor
• CPC Class Codes: F01N 2560/08 the means being a pressure sensor
• CPC Class Codes: F01N 2900/1404 Exhaust gas temperature
• CPC Class Codes: F01N 2900/1406 Exhaust gas pressure
• CPC Class Codes: F01N 3/005 for draining or otherwise eliminating condensates or moisture accumulating in the apparatus F01N3/02 takes precedence
• CPC Class Codes: F01N 3/038 by means of perforated plates defining expansion chambers associated with condensation and collection chambers, e.g. for adiabatic expansion of gases and subsequent collection of condensed liquids
• CPC Class Codes: F01N 5/02 the devices using heat
• CPC Class Codes: F02M 26/15 in relation to engine exhaust purifying apparatus
• CPC Class Codes: F02M 26/25 with coolers having bypasses
• CPC Class Codes: F02M 26/29 Constructional details of the coolers, e.g. pipes, plates, ribs, insulation or materials
• CPC Class Codes: F02M 26/49 Detecting, diagnosing or indicating an abnormal function of the EGR system
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

Methods and systems are provided for carrying out on-board diagnostics of a plurality of components of an exhaust heat exchange system. In one example, degradation of one or more of a heat exchanger and a coolant system fluidically coupled to the heat exchanger may be detected based on a first temperature estimated upstream of the heat exchanger, a second temperature sensor estimated downstream of the heat exchanger, a coolant temperature, and a pressure estimated upstream of the heat exchanger. Also, degradation of a diverter valve of the heat exchange system may be detected based on inputs of a position sensor coupled to the diverter valve.

Claims

1. A method, comprising:

diverting engine exhaust for a turbo-charged direct injection engine, via a diverter valve of a heat exchange system, from downstream of an exhaust catalyst and downstream of a turbocharger turbine into a heat exchanger in an exhaust bypass; and

indicating degradation of the heat exchange system based a first exhaust temperature and an exhaust pressure estimated upstream of the heat exchanger, a second exhaust temperature estimated downstream of the heat exchanger, and a temperature of coolant circulating through the heat exchanger sensed by a temperature sensor, the coolant returned to the engine or a heater core from the heat exchanger.

2. The method of claim 1, wherein the indicating is further based on a position of the diverter valve relative to a commanded position.

3. The method of claim 2 wherein, the commanded position is based on engine heating demand.

4. The method of claim 3 wherein, the diverter valve is coupled to a junction of an outlet of the exhaust bypass and a main exhaust passage.

5. The method of claim 1, wherein the heat exchange system further includes an exhaust gas recirculation (EGR) passage for recirculating exhaust from the exhaust bypass, downstream of the heat exchanger, to an engine intake manifold via an EGR valve.

6. The method of claim 5, and wherein the indicating is further based on an actual position of the EGR valve.

7. The method of claim 6, further comprising:

operating the heat exchange system in a first, heat recovery mode by actuating the EGR valve to a closed position and actuating the diverter valve to a first position to enable exhaust flow to the tailpipe via the heat exchanger.

8. The method of claim 6, further comprising:

operating the heat exchange system in a second, EGR mode by actuating the EGR valve to an open position and actuating the diverter valve to a second position to enable exhaust flow to the engine intake manifold via the heat exchanger.

9. The method of claim 6, further comprising:

operating the heat exchange system in a third, bypass mode by actuating the EGR valve to the closed position and actuating the diverter valve to the second position to enable direct exhaust flow to the tailpipe, bypassing the heat exchanger, wherein the indicating is performed during each of the first, second, and third modes.

10. The method of claim 7, wherein the indicating includes:

when operating the heat exchange system in the first mode, indicating degradation of the heat exchanger responsive to the second exhaust temperature being lower than an expected second exhaust temperature and the estimated exhaust pressure being higher than an expected exhaust pressure.

11. The method of claim 8, wherein the indicating includes:

when operating the heat exchange system in the second mode, indicating degradation of the heat exchanger responsive to each of the second exhaust temperature being lower than an expected second exhaust temperature and the estimated exhaust pressure being higher than an expected exhaust pressure.

12. The method of claim 7, wherein the indicating includes:

when operating the heat exchange system in the first mode, indicating degradation of a coolant system circulating coolant through the heat exchanger responsive to the estimated coolant temperature being lower than an expected coolant temperature.

13. The method of claim 9, wherein the indicating includes:

when operating the heat exchange system in the third mode, indicating degradation of the diverter valve responsive to an actual position of the diverter valve differing from an expected position of the diverter valve.

14. The method of claim 1, wherein the first exhaust temperature is estimated via a first temperature sensor coupled to the exhaust bypass, upstream of the heat exchanger.

15. The method of claim 1, wherein the second exhaust temperature is estimated via a second temperature sensor coupled to the exhaust bypass, downstream of the heat exchanger.

16. The method of claim 1, wherein the exhaust pressure is estimated via a pressure sensor coupled to the exhaust bypass, upstream of the heat exchanger.

17. The method of claim 1, further comprising, responsive to the indication of degradation, disabling the diverting of exhaust through the heat exchanger in the exhaust bypass;

and enabling direct flow of exhaust to a tailpipe via a main exhaust passage, bypassing the heat exchanger.

18. A method, comprising:

generating exhaust gas form a direct injection turbocharged engine;

while operating a heat exchange system to flow an entire volume of the exhaust from downstream of an exhaust catalyst to atmosphere via an exhaust bypass housing a heat exchanger,

indicating degradation of the heat exchanger responsive to each of an exhaust pressure measured upstream of the heat exchanger being higher than a first threshold pressure, and a temperature difference between a first exhaust temperature measured upstream of the heat exchanger and a second exhaust temperature measured downstream of the heat exchanger being higher than a first threshold difference;

indicating degradation of a coolant system circulating coolant through the heat exchanger responsive to coolant temperature measured at an outgoing line of the coolant system being lower than a first threshold coolant temperature; and

indicating a diverter valve coupled at a junction of the exhaust bypass and a main exhaust passage is stuck closed or partially open responsive to an actual position of the diverter valve differing from a fully open position.

19. The method of claim 18 further comprising:

based on EGR demand, recirculating a portion of the exhaust from downstream of the heat exchanger to an engine intake manifold via an exhaust gas recirculation (EGR) valve; and

during the recirculating, while the EGR valve is not degraded,

indicating degradation of the heat exchanger responsive to each of the exhaust pressure measured upstream of the heat exchanger being higher than a second threshold pressure, and the temperature difference between the first exhaust temperature measured upstream of the heat exchanger and the second exhaust temperature measured downstream of the heat exchanger being higher than a second threshold difference;

indicating degradation of the coolant system responsive to coolant temperature measured at the outgoing line of the coolant system being lower than a second threshold coolant temperature; and

indicating the diverter valve is stuck open or partially open responsive to the actual position of the diverter valve differing from a fully closed position.

20. The method of claim 18, further comprising:

while operating the heat exchange system to flow exhaust from downstream of the exhaust catalyst to the tailpipe via the main exhaust passage bypassing the heat exchanger,

indicating degradation of one of a first temperature sensor coupled to the bypass passage upstream of the heat exchanger and a second temperature sensor coupled to the bypass passage downstream of the heat exchanger responsive to the temperature difference between the first exhaust temperature measured upstream of the heat exchanger and the second exhaust temperature measured downstream of the heat exchanger being higher than a third threshold difference;

indicating degradation of a pressure sensor coupled to the bypass passage upstream of the heat exchanger responsive to a pressure difference between the exhaust pressure and atmospheric pressure being higher than a threshold pressure difference;

indicating degradation of a third temperature sensor coupled to the coolant line responsive to the coolant temperature measured at the outgoing line of the coolant system being lower than a third threshold coolant temperature; and

indicating the diverter valve is stuck open position or partially open responsive to the actual position of the diverter valve differing from the fully closed position.