Hydraulic Radial-piston Pump for Wind Turbines

Abstract

A hydraulic radial-piston pump transfers the wind energy of the rotor to an adjustable hydraulic motor on ground level, driving an electric generator with constant speed. The pump consists of piston assemblies, located in radial direction between camshaft and housing, supported by spherical bearings at the housing and cylindrical bearings at the camshaft, allowing for self-adjustment of the assemblies. The radial and axial bearings of the camshaft are pivotally mounted allowing for self-adjustment to the housing. At least two planes with cams opposing each other compensate the piston forces in radial direction. Preferably, the pump has four planes symmetrically arranged around a plane between the second and third plane, compensating the piston forces in axial direction. The center of gravity of the rotor is located between or near the bearings of the camshaft. The loads are supported by hydraulic pressure fields, minimizing frictional losses and increasing longevity.

Description

BACKGROUND OF THE INVENTION[0001]1. Technical Field[0002]The invention relates to a hydrostatic transmission, transferring the power from the rotor of a wind turbine or other high torque-low speed applications like water turbines, to the electric generator through pressurized fluid. The transmission consists of a hydraulic radial-piston pump integrated into the rotor hub and axial-piston motor with variable displacement driving the generator with constant speed.[0003]Currently, geared transmissions are utilized to increase the low rotational speed of the rotor to the high speed needed at the generator. The inconsistent speed of the generator requires a complex circuitry and the gear boxes have a short operational life span and cause extensive costs for maintenance and overhaul. The high weight of the rotor, nacelle, gear box and generator on top of the tower requires a heavy tower and foundation. New drivetrain systems are utilized where the rotor drives a low speed generator direct...

AI Technical Summary

Benefits of technology

The present invention provides a new hydraulic pump for wind turbines that reduces friction and wear, minimizes leakage and misalignment, and compensates for deformation and misalignment of the components. The piston assemblies are arranged in a way that eliminates bearing forces at the cam shaft, and the bearings self-adjust to compensate for deformation and misalignment of the housing and the cam shaft. The hydraulic force of an axial hydrostatic bearing at the opposing face of the camshaft balances the wind forces and reduces friction and compression losses. These features make the hydraulic pump highly efficient and reliable for wind energy conversion.

Problems solved by technology

The mechanism contains is space consuming, and the movement of the larger number of additional parts will reduce the gains in efficiency from the piston assembly.

The high loads and large size of the roller bearings result in high costs, and the limited space in axial direction does not favor the use of hydrostatic rings.

The circular shaped cylinder end requires large space for the bearing in circumferential direct at the spherical cam lobe, reducing the number of piston assemblies arranged around the cam shaft and increasing the manufacturing costs.

The efficiencies, life expectancies, and scalability of hydraulic pumps and motor of prior art are insufficient to use hydrostatic drive systems for large powers at low speeds, like wind or water turbines.

The proportionally increasing manufacturing tolerances, misalignments, and deformation of components, significantly increase the contact forces and leakage due to tilting, leading to lower efficiencies and excessive wear and likely destruction.

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