Auxiliary Pump Control for Idle-Stop Transmission Pressure
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Solution Overview
Problem
Existing engine idle-stop systems face issues such as continuous operation of electric pumps degrading fuel savings and accelerating wear-and-tear, and systems that rely on accumulators for pressure maintenance can increase restart time and limit successive restart events.
Innovation Solution
A method that selectively uses an auxiliary electric pump and an accumulator to maintain hydraulic pressure in the transmission, with the pump's operation adjusted based on accumulator pressure, and flow through secondary components like the oil cooler is stopped during engine shutdown to reduce energy demands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the auxiliary electric pump operates continuously to maintain transmission fluid pressure during engine idle-stop, then the transmission can be launched rapidly, but fuel savings are degraded and pump wear-and-tear accelerates
Solution Approach 1:
The patent implements periodic action by controlling the auxiliary electric pump to operate only during specific periods when accumulator pressure falls below threshold levels, rather than continuous operation. The pump is activated intermittently to recharge the accumulator, maintaining pressure only when necessary, thereby reducing overall energy consumption and fuel usage while still ensuring rapid vehicle launch capability when needed.
2Speed
If the auxiliary electric pump operates continuously to maintain transmission fluid pressure, then the transmission can be launched rapidly, but pump wear-and-tear accelerates
Solution Approach 1:
The patent implements periodic action by controlling the auxiliary electric pump to operate only during specific periods when accumulator pressure falls below threshold levels, rather than continuous operation. The pump is activated intermittently to recharge the accumulator, maintaining pressure only when necessary, thereby reducing overall operational hours and wear-and-tear on the pump components, extending its service life while still ensuring rapid vehicle launch capability when needed.
3Reliability
If the electric pump provides flow through all hydraulic circuit components including the oil cooler, then complete hydraulic functionality is maintained, but energy consumption increases due to compensating for leakage
Solution Approach 1:
The patent applies the extraction principle by removing the oil cooler from the hydraulic circuit during engine idle-stop conditions. A valve isolates the oil cooler, preventing transmission fluid from flowing through it. This eliminates unnecessary energy consumption associated with pumping fluid through the cooler and compensating for leakage in that section of the circuit, while maintaining essential hydraulic functionality for transmission operation.
4Speed
If the accumulator is discharged at engine restart, then transmission hydraulic pressure is maintained for rapid launch, but the accumulator requires recharging which increases restart time and limits successive restart events
Solution Approach 1:
The patent applies preliminary action by continuously maintaining the accumulator charged during engine idle-stop conditions through controlled operation of the auxiliary electric pump. Rather than discharging and then recharging the accumulator at restart, the system proactively keeps the accumulator pressurized throughout the idle-stop period, eliminating restart preparation time and enabling immediate successive restart events without delay.
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 the frequency and duration of auxiliary pump operation, leading to energy and fuel savings while maintaining rapid engine restart quality and extending component life.
Implementation Method 1
an accumulator, and an auxiliary transmission fluid pump... delivering pressurized transmission fluid to the hydraulic circuit from the accumulator
Implementation Method 2
an auxiliary transmission fluid pump... operating the auxiliary pump and delivering at least some pressurized transmission fluid to the hydraulic circuit from the operating pump
Data Source
AI summary
Systems and methods are provided for controlling a vehicle system including an engine that is selectively shut-down during engine idle-stop conditions, the system further including a hydraulic circuit comprising a hydraulically actuated transmission component, an accumulator, and an auxiliary transmission fluid pump. One example method comprises, during a first idle-stop engine shut-down condition, where the accumulator pressure is above a threshold, delivering pressurized transmission fluid to the hydraulic circuit from the accumulator, while disabling the auxiliary pump. The method further comprises, during a second idle-stop engine shut-down condition, where the accumulator pressure is below the threshold, operating the auxiliary pump and delivering at least some pressurized transmission fluid to the hydraulic circuit from the operating pump without travelling through the accumulator.