Accumulator Fluid Mixing for Engine Start-Stop
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Solution Overview
Problem
The temperature difference between hydraulic fluid in an accumulator and the transmission can inhibit engine start/stop functionality, particularly in low ambient temperatures, affecting fuel economy and transmission performance.
Innovation Solution
A system and method for controlling accumulator fluid by determining temperature indicators such as ambient air temperature, transmission fluid temperature, and time since last discharge/charge, and adjusting the accumulator's state by discharging or charging it to maintain optimal fluid temperature for engine start/stop operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the accumulator is located outside the transmission, then the engine start/stop functionality can be implemented, but the hydraulic fluid temperature in the accumulator becomes lower than in the transmission, preventing proper engine start/stop operation
Solution Approach 1:
The system uses periodic discharge/charge cycles of the accumulator to mix the hydraulic fluid and equalize temperatures. The control module monitors temperature indicators and triggers discharge events at appropriate intervals to maintain temperature homogeneity between the accumulator and transmission fluid, enabling proper engine start/stop operation.
2Use of energy by moving object
If the hydraulic fluid temperature difference between accumulator and transmission is large, then fuel economy can be improved through engine stop, but transmission performance deteriorates
Solution Approach 1:
The control module continuously monitors temperature indicators including ambient temperature, transmission fluid temperature at charging time, and current transmission fluid temperature. Based on this feedback, the system determines when to discharge the accumulator to mix fluids and equalize temperatures, ensuring transmission performance requirements are met while maximizing fuel economy through engine stop functionality.
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
Enables proper engine start/stop functionality and improved fuel economy by ensuring hydraulic fluid temperature in the accumulator is synchronized with the transmission fluid temperature, enhancing transmission performance.
Implementation Method 1
discharging/charging the accumulator to mix the hydraulic fluid located in the accumulator with the hydraulic fluid in the transmission
Data Source
AI summary
A system and method for controlling an accumulator for use with a hydraulic circuit is provided. The system and method is configured to determine a set of accumulator temperature indicators and discharge and charge the accumulator as a function of the set of accumulator temperature indicators.