Axial Piston Control Valve Emergency Pressure Segmentation
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Solution Overview
Problem
Axial piston machines face safety-critical malfunctions due to failures in the control valve's input signal, such as cable breaks or mechanical defects, leading to unintended pressure levels that can disrupt the operation of the swash plate and pistons.
Innovation Solution
A control valve design that allows for emergency operation by selectively connecting the adjustment chamber to either high or low pressure inlets, ensuring the axial piston machine can maintain operation at either maximum or minimum pivot angles, even in the absence of external control signals, through a mechanism involving multiple control edges and a feedback spring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the control valve is designed with a single control edge for normal operation, then the device complexity is reduced, but the reliability deteriorates because the system cannot handle emergency conditions with unintended pressure levels
Solution Approach 1:
The control valve is segmented into multiple control edges (first control edge, second control edge, third control edge) that can be independently activated. Each control edge handles specific pressure conditions, allowing the system to respond differently to normal operation versus emergency conditions with unintended pressure levels, thereby improving reliability without requiring a complete redesign of the control mechanism
Solution Approach 2:
The control valve transitions from a static single-control-edge design to a dynamic multi-control-edge design where the active control edge changes based on operating conditions. The piston position dynamically determines which control edge is active, enabling the system to adapt to varying pressure conditions and maintain reliability across different operational states
2Productivity
If the control valve connects the adjustment chamber to the high pressure inlet during emergency operation, then the pivot angle is set to maximum enabling continued operation, but the pressure level increases which may cause harmful effects
Solution Approach 1:
The control valve converts the harmful effect of unintended high pressure during emergency operation into a beneficial outcome. By detecting the high pressure condition and automatically connecting the adjustment chamber to the high pressure inlet via the third control edge, the system uses the available high pressure to set the pivot angle to maximum, enabling the machine to continue operating at full capacity despite the emergency condition
Solution Approach 2:
The control valve incorporates feedback through the piston position that responds to pressure conditions in the system. The piston automatically positions itself based on the pressure level, activating the appropriate control edge. This feedback mechanism ensures that when high pressure is detected during emergency operation, the system responds by connecting to the high pressure inlet, thereby maintaining productivity while managing the pressure condition
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
Enables the axial piston machine to continue operating safely and effectively in emergency conditions by setting the pivot angle to either maximum or minimum, preventing system shutdown and ensuring continued functionality.
Implementation Method 1
a control valve design that allows for emergency operation by selectively connecting the adjustment chamber to either high or low pressure inlets
Data Source
AI summary
The invention relates to an axial piston machine having a swash plate, a drive shaft having a driving mechanism, one or more driving mechanism pivots displaceable therein and whose piston stroke can be set by the swash plate, a mechanical adjustment unit for changing the pivot angle of the swash plate, and an externally controllable control valve. The control valve has a valve housing having a control displaceable control piston, with the adjustment device being hydraulically actuable by the control valve. An adjustment chamber of the control valve is connectable in dependence on the switched state of the control valve to a high pressure inlet or to a low pressure inlet for the hydraulic pressurization of the adjustment device via a setting pressure connection radially extending through the control piston. A connection between a high pressure inlet and a setting pressure connection can be selectively established in regular operation via a first control edge or between the low pressure inlet and the setting pressure connection via a second control edge. In a first aspect, a connection can be established between the low pressure inlet or high pressure inlet via a further control edge in emergency operation without an active control. In a second aspect, a control pressure inlet of the control valve is connectable to a hydraulic tank or to a hydraulic source via an integrated or attached valve. The invention further relates to a control valve for an axial piston machine in accordance with the first aspect.