Hydraulic Transmission Control Device for Shift Shock Reduction
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Solution Overview
Problem
Hydraulic automatic transmissions experience uncomfortable shocks and degraded starting characteristics due to high temperatures affecting hydraulic fluid viscosity and engagement control, leading to unstable torque transmission during shifts from neutral to drive ranges.
Innovation Solution
A control device that inhibits high-speed position setting operations when temperature or hydraulic pressure thresholds are exceeded, ensuring stable hydraulic pressure and smoother shifts by prioritizing low-speed position engagement, and includes temperature and pressure detection systems to manage these conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If high-speed position setting operation is performed to smooth output torque change, then shift shock is reduced, but starting characteristics are degraded at high temperature
Solution Approach 1:
The control device changes the operational parameters of the high-speed position setting operation based on temperature conditions. When temperature is high, the operation is inhibited or modified to prevent degradation of starting characteristics. This dynamic parameter adjustment resolves the contradiction by adapting the shock-reduction mechanism to thermal conditions.
Solution Approach 2:
The control device predicts potential degradation of starting characteristics due to high temperature and preliminarily inhibits the high-speed position setting operation before degradation occurs. This preventive approach prevents the harmful effect while maintaining shift smoothness through alternative control strategies.
2Object-affected harmful factors
If high-speed position setting operation is performed frequently, then shift shock is reduced, but temperature of hydraulic engaging element increases
Solution Approach 1:
The control device implements periodic monitoring of temperature and alternates or limits the execution of high-speed position setting operations based on thermal state. This periodic control prevents excessive temperature accumulation while maintaining adequate shift shock reduction through timed operational intervals.
Solution Approach 2:
Instead of fully executing the high-speed position setting operation every time, the control device applies partial action by inhibiting or reducing the operation frequency when temperature thresholds are approached. This partial execution maintains sufficient shock reduction while preventing thermal overload.
3Stability of the object's composition
If viscosity of working fluid increases at low temperature, then hydraulic pressure control is stable, but time required for switching shift position increases
Solution Approach 1:
The control device adjusts hydraulic pressure parameters and engagement control strategies based on temperature conditions. At low temperatures, modified pressure profiles and engagement sequences compensate for high viscosity, maintaining control stability while reducing switching time through optimized control parameters.
Solution Approach 2:
The control device performs preliminary warming or pre-conditioning of the hydraulic system before full engagement operations. This preliminary action reduces the initial viscosity impact and prepares the system for faster switching while maintaining stable pressure control during the transition.
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
Prevents degradation in starting characteristics by maintaining stable hydraulic pressure and reducing shift shocks, even at high temperatures, through precise control of hydraulic engaging elements.
Implementation Method 1
temperature detecting means for detecting the temperature of a power train
Implementation Method 2
hydraulic pressure detecting means for detecting a hydraulic pressure to be supplied to the second hydraulic engaging element
Data Source
AI summary
A control device for a hydraulic automatic transmission for a vehicle, including start control device for supplying a hydraulic pressure to a first hydraulic engaging element for a low-speed position and a second hydraulic engaging element for a high-speed position in performing in-gear control by a select operation from a nonforward range to a forward range, thereby first setting a shift position to the high-speed position and next switching the high-speed position to the low-speed position; temperature detecting device for detecting the temperature of a power train; and high-speed position setting operation inhibiting device for inhibiting a high-speed position setting operation by the start control device in the case that the temperature detected by the temperature detecting device is greater than or equal to a predetermined value.