Hydraulic Actuator Fast-Fill Control for Air Pocket Compensation
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Solution Overview
Problem
Hydraulic actuators in vehicle drive systems face delays and inaccuracies in pressure profile due to air pockets, leading to inefficient torque transmission and shifting comfort issues, often requiring expensive sensors for accurate compensation.
Innovation Solution
Adjusting the fast fill phase and pressure of hydraulic actuators based on operating variables outside the hydraulic system, such as prime mover torque or temperature, to minimize the deviation between target and actual pressure profiles without the need for additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fast fill phase is extended to compensate for air pockets, then the filling completeness is improved, but the response time increases and actuating accuracy deteriorates
Solution Approach 1:
The patent applies dynamics by making the fast fill phase duration adaptive rather than fixed. The control unit dynamically adjusts the fast fill phase length based on detected operating conditions (temperature, standstill time, drive mode) to optimally compensate for air pockets while maintaining response time. This resolves the contradiction by making the system flexible rather than static.
Solution Approach 2:
The patent changes physical parameters (temperature, pressure, time) to predict and compensate for air pocket formation. By monitoring temperature and standstill time, the system calculates expected air volumes and adjusts the fast fill phase accordingly. This parameter-based approach allows the system to maintain both filling completeness and response time.
2Measurement precision
If sensors are added to detect air pockets and adjust fast fill phase, then actuating accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses existing operating parameters (temperature sensors, standstill time detection, drive mode signals) as intermediaries to indirectly detect air pocket conditions. Instead of adding direct air detection sensors, the system uses these intermediate parameters to predict air formation and adjust the fast fill phase accordingly, maintaining accuracy without increasing complexity.
Solution Approach 2:
The system uses its own existing sensors and operational data to detect and compensate for air pockets. The control unit leverages temperature, time, and drive mode information already available in the system to calculate air volumes and adjust fast fill phase, making the system self-diagnosing without external or additional sensing infrastructure.
3Speed
If the fast fill pressure is increased to overcome air gaps quickly, then the speed of actuation is improved, but the risk of foaming and air collection increases
Solution Approach 1:
The patent applies periodic or phased action by dividing the filling process into distinct phases: an initial fast fill phase at high pressure to overcome air gaps quickly, followed by a stabilization phase where pressure is reduced to allow air to escape and prevent foaming. This phased approach maintains actuation speed while eliminating the harmful effects of excessive pressure.
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 simplifies the design, reduces costs, and improves the responsiveness and accuracy of hydraulic actuator operation by accounting for air pockets without sensor outlay, enhancing power transmission and shifting comfort.
Implementation Method 1
the actuator is to be filled with an operating medium, usually hydraulic or transmission oil, and pressurized. The pressurization is carried out in a fast fill phase and a pressure build-up phase.
Implementation Method 2
In the case of hydraulic actuators for friction-locking shift elements, such as multi-disk clutches, then, in the pressure build-up phase, the mutually frictional shift element halves are pressed against one another, under a hydraulic pressure, to an increasingly greater extent until a rotationally fixed coupling exists between the shift element halves.
Implementation Method 3
In the case of hydraulic actuators for shifting rails, which are, for example, cylinder-piston units, the hydraulically generated movement results in the displacement of the associated gear shift sleeves and, in this way, a gear is engaged or disengaged in a form-locking manner.
Data Source
AI summary
A method for operating a hydraulic actuator for a prime mover or a drive device of a vehicle includes determining that the hydraulic actuator is to be actuated via an actuating system and detecting an operating variable influenced by a filling state of the hydraulic actuator indicative of pressure conditions in the hydraulic actuator, with the operating variable being separate from actuator operating variables of the hydraulic actuator and the actuating system. The method further includes pressurizing the actuator during a fast fill phase to one or more pressures over a fast fill time period in response to determining that the hydraulic actuator is to be actuated. The fast fill time period and the one or more pressures are adjusted as a function of the operating variable under certain operating conditions. Additionally, the method includes pressurizing the actuator during a pressure build-up phase after the fast fill phase.