METHOD FOR OPTIMIZING CRUISE CONTROL FUEL ECONOMY IN HEAVY DUTY DIESEL ENGINES

• US 20090164081A1
• Filed: 12/20/2007
• Published: 06/25/2009
• Est. Priority Date: 12/20/2007
• Status: Abandoned Application

• Current Assignee: Detroit Diesel Corporation (Daimler Truck Holding AG)
• Original Assignee: Detroit Diesel Corporation (Daimler Truck Holding AG)
• Inventors: Letang, Dennis M., Michalek, Joseph J., Meloche, Victor J., Blake, Charles C.
• Application Number:
  US11/961,386
• Publication Number:
  US 20090164081A1
• Time in Patent Office: Days
• US Class Current: 701/94
• CPC Class Codes: B60W 2510/0638 Engine speed
• CPC Class Codes: B60W 2552/15 Road slope, i.e. the inclination of a road segment in the longitudinal direction
• CPC Class Codes: B60W 2556/50 of positioning data, e.g. GPS [Global Positioning System] data
• CPC Class Codes: B60W 2710/0666 Engine torque
• CPC Class Codes: B60W 2720/10 Longitudinal speed
• CPC Class Codes: B60W 30/1882 characterised by the working point of the engine, e.g. by using engine output chart

Abstract

A method to operate a vehicle with an electronically controlled internal combustion engine equipped with an electronic control unit with memory and capable of operating the engine in a cruise control mode.

Claims

1. A method to operate a vehicle with an electronically controlled internal combustion engine equipped with an electronic control unit with memory and capable of operating the engine in a cruise control mode, comprising:

a) applying a cruise control set speed;

b) monitoring actual vehicle speed and requested cruise control engine torque to operate vehicle within predetermined limits; and

c) applying a calibratable reduction to said cruise control engine torque proportional to a loss of vehicle speed when said cruise control engine torque exceeds a calibratable horsepower threshold corresponding to a calculated maximum horsepower required to maintain said cruise control set speed on a substantially level surface.

2. The method of claim 1 further including a beyond predetermined calibratable vehicle speed reduction, at which maximum engine torque is made available at that vehicle speed.

3. The method of claim 1, further including calibratable engine brake on speed thresholds to permit said vehicle to given speed and retain inertia when said vehicle is descending a grade to partially prepare to ascend a next grade.

4. The method of claim 1, further including calibratable engine retarder on/off speeds.

5. The method of claim 4, further including determining a simple moving average of vehicle acceleration over a calibratable set of data points to determine average acceleration according to formula:

$\mathrm{AverageAcceleration}=\frac{{\mathrm{Accel}}_m+{\mathrm{Accel}}_{m-1}+\mathrm{\dots <br><br>}<br><br><br><br>{\mathrm{Accel}}_{M-\left(N-1\right)}}{N}$

Wherein;

m is a number and

N is a number of data points.

6. The method of claim 5, further including determining whether said vehicle is descending a grade and how steep is such a grade by measuring whether vehicle speed is greater than cruise set speed, net load is zero and whether average acceleration is positive and greater than or equal to a calibrated threshold.

7. The method of claim 5, wherein a Global Position Satellite (GPS) system is used to determine actual road grade and predicted road grade;

said GPS system having data indicating road grade above a predetermined calibratable threshold.

8. The method of claim 1, wherein said control of vehicle speed and engine torque is non linear.

9. The method of claim 1, further including a timer to delay activation of cruise control is enabled while vehicle is operating at or above a predetermined load.

10. The method of claim 5 further including determining whether a grade is steep by comparing a simple moving average of vehicle acceleration to a predetermined programmable vehicle acceleration threshold.

11. The method of claim 5 further including determining actual horsepower is less than a calibratable maximum horsepower before applying calibratable reduction to the cruise control engine torque.

12. The method of claim 1, further including timer to delay activation when cruise control has been paused and then re-enabled.

13. The method of claim 1, further including a low pass filter on engine brake torque to determine engine torque reduction.

14. The method of claim 4, further including selecting engine retarder on/off thresholds on a per hill basis.