Transfer case ratio diagnostic method for a motor vehicle powertrain
US6278927A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 22, 2000 |
| Grant date | Aug 21, 2001 |
| Priority date | — |
| Expiry date | May 22, 2020 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF16H2061/1284
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
An improved diagnostic control method for a motor vehicle powertrain including an electronically controlled multi-range transmission and a multi-range transfer case, wherein a default determination of transfer case range enables reliable evaluation of transmission ratio, for powertrain configurations with or without a transfer case range indicator switch. An overall speed ratio is computed according to a ratio of the transmission input speed and the transfer case output speed, and the computed ratio is monitored to identify a period of stable operation at the conclusion of transmission shifting and in steady state operation during which the rate of change of the computed ratio is stable over a predefined interval. If the computed ratio is also deemed to be stable, it is compared with an expected overall ratio based on an assumed speed range (low or high) of the transfer case. In configurations having a transfer case indicator switch, the switch state determines the assumed speed range, whereas in configurations not having an indicator switch, a low range of the transfer case is assumed. A default condition of the transfer case is determined based on the ratio comparison, and transm…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.