Internal viscous damper monitoring system and method

• US 20070079785A1
• Filed: 10/07/2005
• Published: 04/12/2007
• Est. Priority Date: 10/07/2005
• Status: Active Grant

• Current Assignee: Volvo Car Corporation (AB Volvo)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Svenske, Erik, Moller, Peter
• Granted Patent: US 7,334,552 B2
• Time in Patent Office: Days
• US Class Current: 123/192.100
• CPC Class Codes: F02D 2200/1012 Engine speed gradient
• CPC Class Codes: F02D 2250/28 Control for reducing torsional vibrations, e.g. at acceleration
• CPC Class Codes: F02D 31/006 for maximum speed control
• CPC Class Codes: F02D 31/009 for maximum speed control
• CPC Class Codes: F02D 41/1497 With detection of the mechanical response of the engine
• CPC Class Codes: G01M 15/12 by monitoring vibrations

Abstract

A method for operating an internal combustion engine of a vehicle traveling on the road, the method comprising of damping engine vibration with a damper coupled to the engine, and when said damping is reduced, preventing engine speed from falling below a threshold value, at least under selected operating conditions, to reduce degradation of the engine that would otherwise occur.

Claims

1. A method for operating an internal combustion engine of a vehicle traveling on the road, the method comprising:

damping engine vibration with a damper coupled to the engine; and

when said damping is reduced, preventing engine speed from rising above a threshold value, at least under selected operating conditions, to reduce degradation of the engine that would otherwise occur.

2. The method of claim 1 wherein said damping is reduced when an amplitude of vibration increases.

3. The method of claim 2 wherein said amplitude is an amplitude of a sixth order harmonic of engine firing frequency.

4. The method of claim 3 wherein a change in said amplitude is used to identify said reduction in damping.

5. The method of claim 4 wherein said a limit of said change is varied with engine operating parameters.

6. The method of claim 2 further comprising identifying said damping is reduced by measuring engine speed fluctuations.

7. The method of claim 6 wherein said measuring is performed under selected operation conditions.

8. The method of claim 7 wherein said operating conditions are based on a transmission state.

9. The method of claim 8 wherein said engine speed is processed using a discrete Fourier Transform.

10. The method of claim 1 wherein said damper is an internal viscous damper.

11. The method of claim 1 wherein said threshold value varies with engine operating conditions.

12. The method of claim 1 wherein said prevention is performed by adjusting a position of en electronically controlled throttle coupled to an intake manifold of the engine.

13. A system for an engine, comprising:

an internal viscous damper coupled to a crankshaft at a front end of the engine, the damper having a fluid located therein having a viscosity selected to reduce engine speed oscillations; and

a controller configured to maintain engine speed below a threshold value, at least under selected operating conditions, when viscosity of a fluid in said damper is reduced, where said threshold value is reduced when said viscosity is reduced.

14. The system of claim 13 wherein said controller is further configured to adjust a throttle position of the engine to maintain engine speed below said threshold value.

15. The system of claim 14 wherein said reduction in viscosity is identified based on at least one of a frequency and amplitude of engine speed oscillations.

16. The system of claim 14 wherein said controller identifies said reduction in viscosity based on an increase in amplitude of engine speed oscillations at a selected speed range.

17. The system of claim 16 wherein said controller is further configured to perform discrete Fourier Transform of engine position data to identify said reduction in viscosity.

18. The system of claim 13 wherein engine is coupled to a transmission of a passenger vehicle traveling on a road.

19. The system of claim 13 wherein said controller is further configured to set a diagnostic code when viscosity of a fluid in said damper is reduced.

20. A method for operating an internal combustion engine of a vehicle traveling on the road, the method comprising:

damping engine vibration with a damper coupled to the engine;

when said damping is reduced, maintaining engine speed below a threshold value, at least under selected operating conditions, to reduce degradation of the engine that would otherwise occur; and

setting a diagnostic code indicating degradation of said damper.