Method for disengaging hydraulic park
US10830351B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Feb 19, 2018 |
| Grant date | Nov 10, 2020 |
| Priority date | — |
| Expiry date | Dec 17, 2038 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB60Y2300/90
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
A hydraulically controlled park system disengages a parking pawl in response to engagement of particular shift elements. When the vehicle is one a grade, greater force may be required to dis-engage the pawl, potentially leading to a failure to dis-engage. The controller avoids this failure by engaging an uphill gear ratio and controlling the transmission input torque to transfer load from the parking pawl to the gearing prior to engaging the shift elements that dis-engage the pawl. Following dis-engagement of the parking pawl, the transmission is in a tie-up condition in which the output shaft is held stationary by shift elements. The controller transitions from this tie-up condition to the selected gear ratio by releasing shift elements.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.