Vehicle Transmission Control Device for Reducing Shift Range Switching Time
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Solution Overview
Problem
Existing control devices for vehicle power transmission systems with automatic and auxiliary transmissions face challenges in reducing the time required to switch gear ranges after gear stage switching, as they often result in prolonged times due to excessive drag torque and engagement of multiple friction engagement elements, especially when starting the vehicle immediately after gear stage switching.
Innovation Solution
The control device strategically disengages and re-engages specific friction engagement elements during gear stage switching of the auxiliary transmission, maintaining engagement of at least one element in the neutral range to reduce drag torque and expedite shift range switching, while executing disengagement and re-engagement processes based on hydraulic oil temperature and predetermined times to optimize gear switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all friction engagement elements are disengaged to establish neutral range, then drag torque is reduced for smooth gear stage switching, but time required to switch shift range increases when vehicle starts immediately after
Solution Approach 1:
The patent segments the friction engagement elements into two groups: those disengaged during neutral range to minimize drag torque, and those maintained in engaged state to enable rapid shift range switching. This segmentation allows simultaneous optimization of both gear stage switching smoothness and shift range switching speed.
Solution Approach 2:
The patent performs preliminary engagement of specific friction engagement elements before vehicle start to prepare the transmission for immediate acceleration. By pre-engaging these elements during the neutral range period, the system eliminates delay when the vehicle needs to start immediately after gear stage switching.
2Ease of operation
If multiple friction engagement elements are engaged simultaneously for shift range switching, then gear train change is achieved, but time required to complete engagement increases due to hydraulic pressure dispersion
Solution Approach 1:
The patent reduces the number of friction engagement elements engaged simultaneously during shift range switching from multiple to just one or two critical elements. This segmentation of engagement actions concentrates hydraulic pressure on fewer elements, dramatically reducing engagement completion time while still achieving the necessary gear train change.
3Loss of time
If friction engagement elements remain engaged in neutral range, then shift range switching is faster, but drag torque increases causing shock or gear stage switching failure
Solution Approach 1:
The patent applies local quality by differentiating the engagement state of different friction engagement elements during neutral range. While most elements are disengaged to minimize drag torque, specific critical elements are maintained in engaged state to provide just enough connection for rapid shift range switching without causing shock or failure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces drag torque and shortens the time needed to switch gear ranges when starting the vehicle after gear stage switching, ensuring efficient gear shifting and preventing prolonged delays, even under varying hydraulic oil temperatures and transmission configurations.
Implementation Method 1
The engagement of the friction engagement elements is performed through supply of hydraulic pressure
Data Source
AI summary
An electronic control unit engages two of friction engagement elements provided in an automatic transmission in a neutral range. The electronic control unit disengages one of the two friction engagement elements engaged in the neutral range at the time of starting gear stage switching of an auxiliary transmission from a low-speed gear stage to a high-speed gear stage in the neutral range, and re-engages the friction engagement element that has been disengaged when determining that the gear stage switching has been completed.