POWER SOURCE SPEED CONTROL IN A MACHINE WITH A CVT

• US 20120136548A1
• Filed: 11/30/2010
• Published: 05/31/2012
• Est. Priority Date: 11/30/2010
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: HOFF, Brian D.
• Granted Patent: US 8,738,250 B2
• Time in Patent Office: Days
• US Class Current: 701/93
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/103 of fluid type
• CPC Class Codes: B60W 2050/0026 Lookup tables or parameter maps
• CPC Class Codes: B60W 2050/0063 Manual parameter input, manual setting means, manual initialising or calibrating means
• CPC Class Codes: B60W 2540/215 Selection or confirmation of options
• CPC Class Codes: B60W 2710/0644 Engine speed
• CPC Class Codes: B60W 2710/1005 Transmission ratio engaged
• CPC Class Codes: B60W 2720/10 Longitudinal speed
• CPC Class Codes: B60W 30/143 Speed control B60W30/16 takes precedence

Abstract

Methods and systems for controlling a power source of a mobile machine having a continuously variable transmission (CVT) are disclosed. In one embodiment, the method includes receiving, from an operator of the mobile machine, input selecting of one of a plurality of target travel speeds of the mobile machine and input indicative of a requested output speed of the power source. The method further includes calculating a difference between the selected target travel speed and an actual travel speed of the mobile machine. Finally, the method includes adjusting the requested output speed of the power source based on the calculated travel speed difference, and commanding the power source based on the adjusted requested output speed of the power source.

Claims

1. A method for controlling a power source of a mobile machine having a continuously variable transmission (CVT), the method comprising:

receiving, from an operator of the mobile machine, input selecting of one of a plurality of target travel speeds of the mobile machine;

receiving, from the operator, input indicative of a requested output speed of the power source;

calculating a difference between the selected target travel speed and an actual travel speed of the mobile machine;

adjusting the requested output speed of the power source based on the calculated travel speed difference; and

commanding the power source based on the adjusted requested output speed of the power source.

2. The method of claim 1, wherein adjusting the requested output speed of the power source includes decreasing the requested output speed of the power source.

3. The method of claim 1, wherein adjusting the requested output speed of the power source includes:

determining a scaling factor for the selected target travel speed that corresponds to the calculated travel speed difference; and

adjusting the requested output speed of the power source based on the scaling factor.

4. The method of claim 3, wherein determining a scaling factor includes:

accessing a scaling map for the target travel speeds, the scaling map mapping differences between the target travel speeds and the actual travel speed of the mobile machine to respective scaling factors; and

looking up the scaling factor on the scaling map based on the calculated travel speed difference.

5. The method of claim 3, wherein determining a scaling factor includes determining a scaling factor such that the adjusted requested output speed of the power source decreases relative to the requested output speed of the power source as the calculated travel speed difference decreases.

6. The method of claim 1, further comprising:

determining whether adjustment of the requested output speed of the power source is permitted for the selected target travel speed; and

adjusting the requested output speed of the power source only when it is determined that adjustment is permitted for the selected target travel speed.

7. The method of claim 6, wherein:

the target travel speeds include respective scaling indicators indicating whether adjustment of the requested output speed of the power source is permitted for the target travel speeds; and

determining whether adjustment is permitted includes identifying the scaling indicator for the selected target travel speed.

8. The method of claim 7, wherein:

the plurality of target travel speeds include a range of target travel speeds; and

determining whether adjustment is permitted includes determining whether the selected target travel speed is above or below a point in the range.

9. A control system for controlling a power source of a mobile machine having a continuously variable transmission (CVT), the system comprising:

a memory storing a plurality of target travel speeds of the mobile machine;

a first operator input device configured to receive from an operator of the mobile machine input selecting one of the plurality target travel speeds;

a second operator input device configured to receive from the operator input indicative of a requested output speed of the power source;

a sensor configured to sense an actual travel speed of the mobile machine; and

a controller configured to;

calculate a difference between the selected target travel speed of the mobile machine and the actual travel speed of the mobile machine;

adjust the requested output speed of the power source based on the calculated travel speed difference; and

command the power source based on the adjusted requested output speed.

10. The system of claim 9, wherein the controller is configured to adjust the requested output speed of the power source by decreasing the requested output speed of the power source.

11. The system of claim 9, wherein, to adjust the commanded output speed of the power source, the controller is further configured to:

determine a scaling factor for the selected target travel speed that corresponds to the calculated travel speed difference; and

adjust the requested output speed of the power source based on the scaling factor.

12. The system of claim 11, wherein:

the memory further stores a scaling map for the plurality of target travel speeds, the scaling map mapping differences between the target travel speeds and the actual travel speed of the mobile machine to corresponding scale factors; and

the controller is configured to determine the scaling factor by looking up the scaling factor on the scaling map based on the calculated travel speed difference.

13. The system of claim 12, wherein the scaling map maps scaling factors such that the adjusted requested output speed of the power source decreases relative to the requested output speed of the power source as the calculated travel speed difference decreases.

14. The system of claim 9, wherein the controller is further configured to:

determine whether adjustment of the requested output speed of the power source is permitted for the selected target travel speed; and

adjust the requested output speed of the power source only when it is determined adjustment is permitted for the selected target travel speed.

15. The system of claim 14, wherein:

the target travel speeds include respective scaling indicators indicating whether adjustment of the requested output speed of the power source is permitted for the target travel speeds; and

the controller is configured to determine whether adjustment of the requested output speed of the power source is permitted based on the scaling indicator for the selected target travel speed.

16. The system of claim 14, wherein:

the target travel speeds include a range of target travel speeds; and

the controller is configured to determine whether adjustment is permitted based on whether the selected target travel speed is above or below a point in the range.

17. A mobile machine, comprising:

at least one traction device configured to propel the mobile machine;

a power source configured to generate a power output;

a continuously variable transmission (CVT) configured to drive the at least one traction device with the power output;

a memory storing a plurality of target travel speeds of the mobile machine;

a first operator input device configured to receive from an operator of the mobile machine input selecting one of the plurality target travel speeds;

a second operator input device configured to receive from the operator input indicative of a requested output speed of the power source;

a sensor configured to sense an actual travel speed of the mobile machine; and

a controller configured to;

calculate a difference between the selected target travel speed of the mobile machine and the actual travel speed of the mobile machine;

adjust the requested output speed of the power source based on the calculated travel speed difference; and

command the power source based on the adjusted requested output speed.

18. The mobile machine of claim 17, wherein the controller is configured to adjust the requested output speed of the power source by decreasing the requested output speed of the power source.

19. The mobile machine of claim 17, wherein, to adjust the requested output speed of the power source, the controller is further configured to:

determine a scaling factor for the selected target travel speed that corresponds to the calculated travel speed difference; and

adjust the requested output speed of the power source based on the scaling factor.

20. The mobile machine of claim 19, wherein:

the memory further stores a scaling map for the plurality of target travel speeds, the scaling map mapping differences between the target travel speeds and the actual travel speed of the mobile machine to corresponding scale factors; and

the controller is configured to determine the scaling factor by looking up the scaling factor on the scaling map based on the calculated travel speed difference.

21. The mobile machine of claim 20, wherein the scaling map maps scaling factors such that the adjusted requested output speed of the power source decreases relative to the requested output speed of the power source as the calculated travel speed difference decreases.

22. The mobile machine of claim 17, wherein the controller is further configured to:

determine whether adjustment of the requested output speed of the power source is permitted for the selected target travel speed; and

adjust the requested output speed of the power source only when it is determined adjustment is permitted for the selected target travel speed.

23. The mobile machine of claim 22, wherein:

the target travel speeds include respective scaling indicators indicating whether adjustment of the requested output speed of the power source is permitted for the target travel speeds; and

the controller is configured to determine whether adjustment of the requested output speed of the power source is permitted based on the scaling indicator for the selected target travel speed

24. The mobile machine of claim 22, wherein:

the target travel speeds include a range of target travel speeds; and

the controller is configured to determine whether adjustment is permitted based on whether the selected target travel speed is above or below a point in the range.

25. A method for controlling a power source of a mobile machine having a continuously variable transmission (CVT), the method comprising:

receiving, from an operator of the mobile machine, input indicative of a requested output speed of the power source;

commanding the power source based on the requested output speed of the power source;

determining whether the power source and the CVT have maintained state-state output for a period of time; and

when it is determined that the power source and the CVT have maintained state-state output for a period of time, overriding the requested output speed of the power source with a reduced requested power source output speed of the power source, and commanding the power source based on the reduced requested output speed of the power source.