Adjustable Hydraulic Axial Piston Engine for Wind Turbines
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Solution Overview
Problem
Current hydrostatic piston engines for wind power plants are limited in size and performance due to restricted oil channel diameters, preventing efficient operation beyond 600 kW, and existing radial piston pumps cannot be adjusted for varying displacement needs, leading to inefficient hydraulic motor performance at low speeds.
Innovation Solution
The design features multiple cylinder-piston units in a circular cylinder receptacle with adjustable stroke and displacement, allowing for variable power and displacement control, eliminating the need for additional housing and using lockable non-return valves for independent unit operation, enabling efficient operation as both pumps and motors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If radial piston pumps are used for hydrostatic drives in wind power plants, then high volume flows and high torques can be achieved, but the pumps cannot be adjusted for varying displacement needs, leading to inefficient hydraulic motor performance at low speeds
Solution Approach 1:
The invention applies the dynamics principle by making the displacement of the radial piston pump adjustable through variable stroke control. The pump can operate with different displacement volumes by changing the stroke length, allowing adaptation to varying operational requirements and maintaining efficient hydraulic motor performance across different speed ranges.
Solution Approach 2:
The invention changes the parameter of stroke length to achieve variable displacement. By adjusting the stroke parameter, the pump can optimize its volume flow and torque output to match the requirements of the hydraulic motor, particularly improving performance at low speeds where previously the system operated inefficiently.
2Length of moving object
If the stroke of the piston is increased to achieve longer strokes, then the distance between the piston and cam plate must increase, but this increases the overall size and weight of the pump
Solution Approach 1:
The invention applies the nesting principle by positioning the piston within the cylinder bore such that the increased stroke length does not proportionally increase the external dimensions of the pump. The piston moves within the confined space of the cylinder, allowing longer strokes without significantly increasing the pump's overall size and weight.
Solution Approach 2:
The invention resolves the contradiction by changing the dimensional arrangement - the increased stroke length is achieved through optimization of the internal geometry and positioning rather than simply extending the external length of the pump. This allows longer strokes while maintaining compact external dimensions and acceptable weight.
3Loss of energy
If the displacement of the pump is reduced to improve hydraulic motor efficiency at low speeds, then the volume flow decreases, but this reduces the power output of the system
Solution Approach 1:
The invention applies dynamics by making the pump displacement variable rather than fixed. The stroke length can be adjusted dynamically to optimize the balance between volume flow and system pressure, allowing the hydraulic motor to operate in its efficient range while maintaining adequate power output through compensating increases in pressure.
Solution Approach 2:
The invention changes the displacement parameter to optimize system performance. By reducing the displacement (volume flow) while increasing system pressure, the hydraulic motor operates more efficiently at low speeds, and the overall power output is maintained through the pressure increase rather than volume flow.
Data Source
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AI summary
The invention relates to a hydraulic axial piston engine for medium and high power outputs, intended for use particularly in wind turbines with a hydrostatic main drive. The object of the invention is to provide an adjustable hydraulic piston engine for various power ratings in the high power range, which can be used both as a slow-running hydraulic pump and as a slow-running hydraulic motor. Power and displacement should be controllable over a wide range. A further object is to reduce the specific weight and ensure a long service life for the moving elements of the hydraulic piston engine. This object is achieved by the features of claim 1.Several cylinder-piston units (01) are detachably mounted as independent assemblies in corresponding bores of an annular cylinder receptacle 02, and the cylinder receptacle (02) is rigidly connected to the stationary part (03) of a rotor bearing or frame element. The required power output and displacement volume are determined by the number of identical cylinder/piston units (01), and the specific displacement volume is fine-tuned to the characteristics of the rotor of the wind turbine or drive by varying the stroke rate and stroke height of the cam disc (04).