Hydraulic Accumulator Actuation with Holding Device
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Solution Overview
Problem
The existing hydraulic accumulator devices in transmission systems face challenges in maintaining an operating state with varying volume profiles, leading to uncontrolled fluid release and inability to switch between different operating states, resulting in inefficient fluid management and potential fuel consumption increases.
Innovation Solution
A method is introduced to actuate the hydraulic accumulator device by varying the storage space volume from minimum to maximum using pressurized hydraulic fluid, setting a threshold pressure to overcome return tendencies and ensuring filling pressure is maintained by a holding device, with strategic pressure changes during vehicle coasting and engine start-stop functions to optimize fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the holding device latches the hydraulic accumulator device in a maximum volume operating state, then the hydraulic fluid can be stored without pressure, but the device cannot be switched to different operating state profiles and uncontrolled fluid release occurs
Solution Approach 1:
The holding device is designed with a dynamic latching mechanism that can be activated or deactivated based on control signals. The latching element can engage to hold the piston in the maximum volume position or disengage to allow controlled movement to other operating states, enabling the system to adapt between different operating profiles while maintaining reliability when latched.
Solution Approach 2:
The system changes the pressure parameter dynamically to control the accumulator device. By adjusting the hydraulic pressure above a threshold value, the device can overcome the latching force and transition between operating states. This parameter-based control enables versatile operation while maintaining stable holding when the pressure remains below the threshold.
2Reliability
If pressurized hydraulic fluid is applied to fill the storage space to maximum volume, then the accumulator can be filled reliably, but transmission pump absorption torque increases leading to higher fuel consumption
Solution Approach 1:
The hydraulic accumulator device is filled to maximum volume in advance during periods when the transmission pump has excess capacity, such as during vehicle coasting or engine overrun. This preliminary filling action ensures the accumulator is ready for future use without requiring high-power pumping operations at critical moments, thereby reducing overall energy consumption while maintaining reliable filling capability.
Solution Approach 2:
The system employs periodic or strategic pressure increases to fill the accumulator rather than continuous high-pressure operation. By timing the filling operations to coincide with periods of low transmission demand or engine overrun conditions, the system achieves reliable accumulation of hydraulic fluid while minimizing the impact on fuel consumption through intermittent rather than continuous energy-intensive pumping.
3Ease of operation
If the latching mechanism is deactivated to allow fluid release, then the switching element can be controlled, but the hydraulic fluid is released uncontrolled due to return tendency
Solution Approach 1:
The holding device acts as an intermediary mechanism between the latching mechanism and the hydraulic fluid. When the latching mechanism is deactivated, the holding device provides an additional layer of control that prevents uncontrolled fluid release by maintaining mechanical constraint on the piston until the fluid pressure naturally equalizes, thereby enabling switching element control while preserving fluid release reliability.
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 method ensures reliable filling of the accumulator chamber, maintains efficient transmission pump operation, and minimizes fuel consumption by controlling pressure changes, thereby enhancing the hydraulic system's functionality and reducing unnecessary pressure fluctuations.
Implementation Method 1
The volume of the storage space can be converted from its minimum to its maximum by applying pressurized hydraulic fluid to the storage space from a pressure supply of the transmission device
Implementation Method 2
a holding device is provided for holding the hydraulic accumulator device at least in the operating state that is equivalent to the maximum volume of the accumulator space, counter to the attempt to restore it
Data Source
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AI summary
A method for actuating a hydraulic accumulator (5) of a transmission system with an accumulator chamber (9) whose volume is variable between a minimum and a maximum is described. The volume of the accumulator chamber (9) can be increased from its minimum to its maximum by pressurizing the accumulator chamber (9) with hydraulic fluid from a pressure supply (19) of the transmission system. To overcome a tendency of the hydraulic accumulator (5) to return to its restoring state, the pressure must be adjusted from an operating state that differs from the operating state equivalent to the minimum volume to an operating state equivalent to the minimum volume of the accumulator chamber (9) to a threshold value.A holding device (12) is provided for holding the hydraulic accumulator (5) at least in the operating state equivalent to the maximum volume of the accumulator chamber (9), against its tendency to spring back. According to the invention, the accumulator chamber (9) is pressurized by the pressure supply (19) at least to a pressure value corresponding to the threshold value (P_threshold) until the hydraulic accumulator (5) has reached the operating state in which it can be held by the holding device (12).