Multi-Chamber Hydropneumatic Accumulator for Rotary Hydraulic Systems
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Solution Overview
Problem
Existing hydraulic hybrid systems face inefficiencies in energy conversion due to dependency on system pressure for charging and discharging the hydraulic accumulator, leading to energy loss through throttling and inadequate operating behavior when using variable displacement pumps.
Innovation Solution
A hydraulic hybrid system with a piston accumulator having multiple pressure chambers of varying sizes, connected via an adjustment assembly and controlled by a logic unit, allowing energy recycling independent of pre-charge pressure and system pressure, enabling optimal energy conversion across all operating states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a single-pressure hydraulic accumulator is used, then the system structure is simple, but energy conversion efficiency deteriorates due to pressure dependency and throttling losses
Solution Approach 1:
The hydraulic accumulator is divided into multiple pressure chambers (first, second, and third pressure chambers) with different precharge pressures. Each chamber can independently store and release hydraulic energy at different pressure levels, allowing the system to match pressure requirements more precisely and reduce throttling losses associated with pressure balancing.
Solution Approach 2:
Different pressure chambers are assigned different precharge pressure characteristics to match different operating conditions. The first pressure chamber has a lower precharge pressure for normal operation, while the second and third chambers have higher precharge pressures for high-demand situations, allowing each part of the accumulator to serve its specific pressure range optimally.
2Loss of energy
If a variable displacement pump is used to mitigate pressure dependency, then energy conversion efficiency improves, but system cost and complexity increase significantly
Solution Approach 1:
The multi-pressure chamber accumulator serves itself by automatically selecting the appropriate pressure chamber based on system pressure requirements. The control unit monitors system pressure and activates the corresponding chamber without requiring complex variable displacement pump mechanisms, thereby achieving adaptive pressure matching through the accumulator's own segmented structure.
3Power
If accumulator pressure is higher than system pressure, then energy can be discharged to the system, but pressure balancing through valves causes energy loss through throttling
Solution Approach 1:
The system changes the pressure parameter by selecting different precharge pressure chambers based on current system requirements. Instead of forcing pressure balancing through throttling valves, the control unit switches between chambers with different precharge pressures to match the required system pressure, thereby delivering power surges without significant throttling losses.
4Ease of manufacture
If system pressure must exceed accumulator precharge pressure for charging, then charging is simple, but energy recycling is limited by system pressure conditions
Solution Approach 1:
The accumulator system dynamically adapts its precharge pressure by switching between multiple pressure chambers during operation. The control unit monitors system pressure conditions and activates the appropriate chamber (first, second, or third) based on real-time requirements, allowing energy recycling across a broader range of pressure conditions while maintaining simple charging operations.
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 enables efficient energy conversion and recycling by selecting appropriate pressure chambers for charging or discharging, reducing energy loss and improving system efficiency regardless of system pressure levels.
Implementation Method 1
the hydraulic accumulator can only be charged when the system pressure is greater than the gas pressure present in the accumulator on the gas side
Implementation Method 2
a piston accumulator (1), in particular a so-called hydropneumatic piston accumulator, on which a filling port (9) for the gas side (7) is located
Data Source
AI summary
A hydraulic hybrid system for rotatory applications has an actuator (49, 91) in the form of a motor pump unit (91). The motor pump unit is coupled to a rotatory-operating device (94) and works as a consumer of hydraulic energy in one operating state of the device (94) and works as a producer of hydraulic energy in another operating state of the device (94). A hydraulic accumulator (1) can be charged by the motor pump unit (91) for energy storage in the one operating state and can be discharged for energy release to the motor pump unit (91) in the other operating state. The hydraulic accumulator is an adjustable hydropneumatic piston accumulator (1) in which a plurality of pressure chambers (19, 21, 23, 25) are delimited by active surfaces (11, 13, 15, 17) of different sizes on the fluid side of the accumulator piston (5). An adjusting arrangement (51) connects a selected pressure chamber (19, 21, 13, 25) or a plurality of selected pressure chambers (19, 21, 23, 25) of the piston accumulator (1) to the actuator (49, 91) depending on the prevailing pressure level on the gas side of the piston accumulator (1) and at the actuator (49, 91).