Terrain adaptive shift scheduling
First Claim
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1. A method of selecting transmission gear ratios comprising:
- maintaining a counter indicating road gradient magnitudes over previously traversed territory;
commanding shifts among discrete gear ratios using a first shift schedule based on changes in a measured speed and a driver demand;
in response to the counter exceeding a threshold, selecting a second shift schedule and commanding shifts among the discrete gear ratios using the second shift schedule;
upon selecting the second shift schedule, recording a location associated with the change in shift schedule; and
in response to subsequent operation using the first shift schedule in a vicinity of the location, selecting the second shift schedule and commanding shifts among the discrete gear ratios using the second shift schedule before the counter exceeds the threshold.
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Abstract
A vehicle implements a method of selecting gear ratios that utilizes two shift schedules, one for flat terrain and one for hilly terrain. Initially, the vehicle switches between the shift schedules based on estimation of the road gradient of a recently traversed route. When the vehicle switched between the shift schedules, the vehicle stores location information associated with the switch. When stored information about previous shift schedule switches is available, the information is utilized, in combination with navigation system data, to switch shift schedules at more appropriate times.
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Citations
17 Claims
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1. A method of selecting transmission gear ratios comprising:
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maintaining a counter indicating road gradient magnitudes over previously traversed territory; commanding shifts among discrete gear ratios using a first shift schedule based on changes in a measured speed and a driver demand; in response to the counter exceeding a threshold, selecting a second shift schedule and commanding shifts among the discrete gear ratios using the second shift schedule; upon selecting the second shift schedule, recording a location associated with the change in shift schedule; and in response to subsequent operation using the first shift schedule in a vicinity of the location, selecting the second shift schedule and commanding shifts among the discrete gear ratios using the second shift schedule before the counter exceeds the threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of operating a vehicle comprising:
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while traversing a route, shifting a transmission according to a first shift schedule; in response to observed road gradients along the route, switching to a second shift schedule at a location; and during a subsequent traversal of the route, switching to the second shift schedule before reaching the location based on navigation system data and stored data about the earlier shift schedule switch. - View Dependent Claims (10, 11, 12, 13)
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14. A vehicle comprising:
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a discrete ratio transmission; a position determining system; and a controller programmed to shift the transmission according to a first shift schedule; switch to a second shift schedule in response to retrospective observation of road gradient; record a location associated with the switch; and in response to subsequent proximity to the location, as determined by the position determining system, switch to the second shift schedule before reaching the location. - View Dependent Claims (15, 16, 17)
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Specification