Actuator Assembly Thermal Volume Compensation Without Bladder Accumulators
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Solution Overview
Problem
Conventional bladder accumulator devices used to compensate for thermal expansion in actuator assemblies are prone to nitrogen gas leaks, requiring frequent maintenance and are inefficient in maintaining system pressure, especially in remote locations where accessing the actuator assembly is costly and time-consuming.
Innovation Solution
An actuator assembly design that includes a cylinder, ram member, collar, spring seat, and resilient member, where the ram member displaces within the cylinder and collar, allowing thermal expansion pressure to be absorbed without exceeding the cracking pressure of the relief valve, thus eliminating the need for bladder accumulator devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bladder accumulator device is used to compensate for thermal expansion, then system pressure can be maintained, but nitrogen gas leaks require frequent maintenance
Solution Approach 1:
The invention removes the bladder accumulator device from the system entirely. Instead of using a bladder with nitrogen gas to compensate for thermal expansion, the patent employs a completely different mechanism involving a relief valve and a compensating piston that uses system fluid itself to absorb thermal expansion, thereby eliminating nitrogen gas leaks and maintenance requirements
Solution Approach 2:
The invention replaces the expensive and maintenance-intensive bladder accumulator with a simple, robust mechanism using conventional components (relief valve, piston, cylinder) that can operate for extended periods without maintenance. The compensating piston design allows the system to tolerate thermal expansion without requiring periodic nitrogen pressure adjustments
2Reliability
If thermal expansion pressure is not compensated, then relief valve triggers and system pressure drops, but manual pump actuation is costly and time-consuming
Solution Approach 1:
The invention implements a self-regulating system where the compensating piston automatically absorbs thermal expansion pressure increases, and the relief valve automatically releases pressure when the piston reaches its travel limit. This eliminates the need for manual intervention or pump actuation, allowing the system to maintain pressure stability autonomously
Solution Approach 2:
The system incorporates automatic feedback control through the relief valve mechanism. When thermal expansion causes pressure to increase, the compensating piston moves to absorb the expansion. When the piston reaches its travel limit, the relief valve automatically opens to release excess pressure, providing continuous automatic pressure regulation without external control
3Reliability
If electrical pump cycles on and off to maintain pressure, then system pressure can be maintained, but cycling operation is undesirable
Solution Approach 1:
The invention removes the need for pump cycling by eliminating the thermal expansion compensation function from the pump system entirely. The compensating piston and relief valve mechanism handles thermal expansion independently, allowing the pump to operate continuously at a steady state without cycling on and off
Solution Approach 2:
The invention separates the thermal expansion compensation function from the pressure maintenance function. The compensating piston specifically handles thermal expansion, while the pump maintains baseline system pressure, allowing both functions to operate independently and smoothly without the need for pump cycling
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 design effectively manages thermal expansion pressures within the actuator assembly, preventing excessive force on the rod member and maintaining system stability without the need for frequent nitrogen pressure adjustments, thereby reducing maintenance costs and improving operational reliability.
Implementation Method 1
A resilient member is disposed within the actuator interior, the resilient member extending along the housing axis from a first end to a second end opposite the first end
Implementation Method 2
fluid under pressure is provided to the cylinder interior to act on the piston head to displace the ram member
Implementation Method 3
During the summer or when the system is subjected to relatively high temperatures, fluid in the system may subject to thermal expansion
Data Source
AI summary
An actuator assembly includes a cylinder disposed in an actuator housing, the cylinder having a cylinder interior is in fluid communication with a source of pressurized fluid. A ram member has a piston head within the cylinder interior, and pressure on the piston head moves the ram member. An end of the ram member acts on a collar having a collar interior, and an end of a rod member is disposed within the collar interior. The rod member is displaceable relative to the collar such that the end of the rod member does not contact the collar. Accordingly, fluid in the cylinder interior acting on the ram member may expand due to thermal expansion without damaging a hard stop at an opposite end of the rod member and without losing system pressure by triggering a relief valve.