Method of determining a current operating range of a transfer case

摘要

A method of determining a current operating range of a transfer case includes continuously calculating current Combined Drive Ratio (CDR), and categorizing the current CDR into one of a pre-determined number of expected CDRs. Counters are used to track when the current CDR is identified as an expected CDR. The different counters are then analyzed using simple mathematical operations to identify which gear ratio the transfer case is currently operating in.

主权项

1. A method of controlling a vehicle, the method comprising:
defining each of a pre-determined number of expected Combined Drive Ratios (CDR) as one of either an expected Verified High CDR, an expected Un-verified High CDR, an expected Verified Low CDR, or an expected Un-verified Low CDR; repeatedly calculating a current CDR of the vehicle by sensing an input speed with a first rotational speed sensor, sensing an output speed with a second rotational speed sensor, and dividing the sensed input speed by the sensed output speed with a processor of a vehicle controller; categorizing the calculated current CDR into one of the pre-determined number of expected CDRs with the vehicle controller; monitoring a period of time the calculated current CDR is categorized in the one of the pre-determined number of expected CDRs with the vehicle controller; incrementing a counter stored in a memory of the vehicle controller for the one of the pre-determined number of expected CDRs, from a value of zero to a value of one, if the monitored time the calculated current CDR is categorized in the one of the pre-determined number of expected CDRs is greater than a minimum time period; further incrementing the counter for the one of the pre-determined number of expected CDRs, from a value of one to a value of two, if the monitored time the calculated current CDR is categorized in the one of the pre-determined number of expected CDRs is greater than a second time period and the one of the pre-determined number of expected CDRs is defined as either an expected Verified High CDR or an expected Verified Low CDR; determining that a transfer case is operating in a low range, with the vehicle controller, when a total counter sum for the expected Verified Low CDRs is equal to or greater than two, or when a total product for the low range CDRs is equal to or greater than one; determining that the transfer case is operating in a high range, with the vehicle controller, when a total counter sum for the expected Verified High CDRs is equal to or greater than two, or when a total product for the high range CDRs is equal to or greater than one; and controlling the operation of the vehicle based on which of the low range or the high range the vehicle controller determines that the vehicle is currently operating in.