Cruise control system and method of operation for downshifting in descent following a repeated or prolonged activation of the driver

Patent metadata

Field	Value
Publication number	US-10024419-B2
Application number	US-201515304982-A
Country	US
Kind code	B2
Filing date	Apr 22, 2015
Priority date	Apr 24, 2014
Publication date	Jul 17, 2018
Grant date	Jul 17, 2018

Abstract

A cruise control system of a motor vehicle includes additional functionality to address increasing vehicle speed on a down gradient. A downshift is commanded upon detection of repeated or prolonged activation of a speed-down control, the additional engine braking reducing vehicle speed to cruise speed in a manner which is within driver expectation.

First claim

The invention claimed is:

1. A method of operating a cruise control system of a vehicle, said system having a driver input to command a reduction in vehicle speed, and an output for causing a downshift of a vehicle transmission, the method comprising:
detecting at least one of repeated activations of said driver input and prolonged activation of said driver input, and in response
causing a downshift of the vehicle transmission.

2. The method of claim 1 , wherein said repeated activations are at a rate greater than 2 Hz.

3. The method of claim 2 , wherein a number of said repeated activations meets or exceeds a threshold of four.

4. The method of claim 1 , wherein said prolonged activation occurs for at least two seconds.

5. The method of claim 1 , wherein said system has a vehicle speed input, and the method is enabled by
detecting an increase in vehicle speed above a pre-set cruise speed.

6. The method of claim 5 , wherein said system has an engine fueling input indicative of instant fueling of a vehicle engine, and the method is enabled by
detecting that fueling of the vehicle engine has substantially ceased.

7. The method of claim 6 , comprising at least temporarily disabling causing when detecting fueling of said vehicle engine.

8. The method of claim 5 , comprising at least temporarily disabling the causing when detecting a vehicle speed at or below the pre-set cruise speed.

9. The method of claim 1 , wherein said system includes a gradient input indicative of instant road gradient, and the method being enabled by
detecting a negative road gradient.

10. The method of claim 9 , comprising at least temporarily disabling the causing when detecting a non-negative road gradient.

11. The method of claim 1 , wherein said output causes a downshift of two or more sequential speed ratios.

12. The method of claim 1 , wherein said system has an indicator of vehicle engine speed, and the method comprises:
continually determining for a plurality of potential downshift ratios, an available amount of engine braking at an instant engine speed;
determining which one of the downshift ratios best achieves a desired vehicle deceleration rate; and
commanding downshift to said one of the downshift ratios.

13. The method of claim 12 , comprising:
continually determining for a plurality of potential upshift ratios, an available amount of engine braking at the instant engine speed;
detecting that vehicle speed is substantially equal to a cruise speed;
determining which one of the upshift ratios best maintains cruise speed; and
commanding an upshift to said one of the upshift ratios.

14. The method of claim 1 , comprising automatically controlling a vehicle engine to attempt to cause vehicle speed to maintain a pre-set cruise speed, wherein at least the causing the downshift of the vehicle transmission is performed during the automatically controlling the vehicle engine.

15. A cruise control system of a motor vehicle, said system comprising:
a driver input to command a cruise speed to be reduced, and
a system output to cause a downshift of a vehicle transmission in response to operation of said driver input by at least one of repeated activations and prolonged activation.

16. A cruise control system according to claim 15 , including a gradient input indicative of road gradient.

17. A cruise control system according to claim 15 , including an engine speed input indicative of instant vehicle engine speed.

18. A cruise control system according to claim 15 , including an engine fueling input indicative of instant fueling of a vehicle engine.

19. An engine and transmission of a motor vehicle incorporating a cruise control system according to claim 15 .

20. A motor vehicle incorporating the engine and transmission of claim 19 .

Assignees

• Jaguar Land Rover Ltd

Inventors

• Lowndes Andi

Classifications

• F16H2061/0237

  Selecting ratios for providing engine braking · CPC title

• F16H61/0213 Primary

  characterised by the method for generating shift signals · CPC title

• B60W10/04

  including control of propulsion units · CPC title

• F16H59/66

  Road conditions, e.g. slope, slippery · CPC title

• F16H59/44

  dependent on machine speed {, e.g. the vehicle speed} (F16H59/46 takes precedence) · CPC title