Automatic Transmission Control Hysteresis Shift Hunting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing control systems for step-variable automatic transmissions in vehicles face a shift hunting phenomenon due to regions where the target vehicle drive force cannot be produced, caused by the torque characteristics of the engine and speed ratios of the transmission, leading to inefficient shifting actions.
Innovation Solution
A control apparatus that sets a target-drive-force-related value and calculates a target throttle valve opening angle to control shifting actions based on predetermined shift boundary lines with hysteresis, preventing immediate shifts back to original speed positions unless determined shift conditions are met, thereby maintaining a predetermined hysteresis between shift-up and shift-down actions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If shifting actions are controlled on the basis of accelerator pedal operating amount and vehicle speed, then the control system is simple, but the shifting action does not match the vehicle drive force when automatic control functions are active
Solution Approach 1:
The patent changes the control parameter from accelerator pedal operating amount to target throttle valve opening angle, which is calculated based on target vehicle drive force. This parameter change ensures that shifting control remains effective even when automatic control functions (like cruise control or VSC) are active, as the throttle valve opening angle directly reflects the actual engine output required to produce the target drive force.
2Measurement precision
If shifting is controlled on the basis of calculated throttle valve opening angle, then the target vehicle drive force is more directly represented, but shift hunting phenomenon occurs in regions where target drive force cannot be produced
Solution Approach 1:
The patent applies preliminary action by determining in advance whether the calculated target throttle valve opening angle falls within a problematic region where shift hunting occurs. When such a region is detected, the system preemptively sets the target throttle valve opening angle to a predetermined value that corresponds to a valid operating point, thereby preventing shift hunting before it occurs.
Solution Approach 2:
The patent introduces an intermediary mechanism (the region determination and predetermined value setting) between the calculated target throttle valve opening angle and the actual shifting control. This intermediary detects when the calculated value would cause shift hunting and replaces it with a predetermined safe value, thus mediating the conflict between precise drive force representation and shifting stability.
3Power
If the target throttle valve opening angle is calculated to precisely match target vehicle drive force, then engine output control is improved, but shift hunting occurs due to engine torque characteristics and transmission speed ratios
Solution Approach 1:
The patent introduces an intermediary mechanism (the region determination and predetermined value setting) between the calculated target throttle valve opening angle and the actual shifting control. This intermediary detects when the calculated value would cause shift hunting and replaces it with a predetermined safe value, thus mediating the conflict between precise drive force representation and shifting stability.
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 solution effectively prevents the shift hunting phenomenon by ensuring that shifting actions maintain a predetermined hysteresis, allowing for stable and efficient engine output matching the target vehicle drive force, even in regions where the target drive force cannot be directly realized.
Implementation Method 1
control shifting actions on the basis of a target opening angle of a throttle valve and a vehicle-speed-related value and according to predetermined shift boundary lines with hysteresis
Data Source
AI summary
A control apparatus for controlling a step-variable automatic transmission of a vehicle to effect a shifting action of the automatic transmission on the basis of a target throttle valve opening angle for realizing a target vehicle drive force, so as to prevent a shift hunting phenomenon of the automatic transmission. The control apparatus includes a shift permitting portion operable to permit a shifting action of the automatic transmission back to an original speed position prior to a previous shifting action to the present n-th speed position, under the control of a shift control portion on the basis of the target throttle valve opening angle in the present speed position and a vehicle speed, if the previous shifting action to the present n-th speed position has been determined by a shift determining portion on the basis of the vehicle speed V and the target throttle valve opening angle which is calculated by a target-throttle-valve-angle calculating portion to obtain an engine torque to realize a target vehicle drive force set by a target-drive-force-related-value setting portion in the present n-th speed position of the automatic transmission, whereby the shift permitting portion inhibits the shifting action back to the original speed position prior to the previous shifting action under the control of the shift control portion on the basis of the target throttle valve opening angle immediately after the previous shifting action, thereby preventing the shift hunting phenomenon.