Fluid Working Machine Shaft Rotation via Secondary Manifold
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Solution Overview
Problem
Existing fluid working machines are unable to rotate their shafts without sufficient external torque, as they lack the capability to absorb and apply energy from a fluid source, and the complex, expensive valves required for such functionality are sub-optimal for pump operations.
Innovation Solution
The fluid working machine incorporates a mechanism where working chambers are mechanically coupled to a rotating shaft, utilizing a pressure differential to generate mechanical work, and includes a fluid path from a secondary high pressure manifold to enable shaft rotation, eliminating the need for complex valves by using a combination of fast and slow high pressure valves controlled by a phase-sensing controller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If complex controllable valves are used to enable motoring cycle and shaft rotation, then the machine can rotate its shaft without external torque, but the device complexity and cost increase significantly
Solution Approach 1:
The fluid working machine is designed to perform multiple functions: it can operate as a pump during normal operation and as a motor during maintenance operations. The working chambers can be selectively connected to different manifolds (primary high pressure, secondary high pressure, or low pressure) to achieve different operational modes, eliminating the need for separate devices for pumping and motoring functions.
Solution Approach 2:
Instead of using complex valves to control fluid flow for shaft rotation, the invention inverts the approach by using the fluid working machine's own working chambers to directly receive high pressure fluid from the secondary manifold. This reverses the typical pump operation where fluid is discharged to a manifold, and instead allows fluid to enter the working chambers to drive the shaft in reverse (motoring mode).
2Ease of operation
If the fluid working machine operates at low cycle rates for shaft rotation, then it can function as a motor for maintenance operations, but the productivity decreases compared to normal pumping operation
Solution Approach 1:
The system dynamically adapts its operating parameters based on the operational mode. During maintenance operations, the machine operates at low cycle rates with controlled fluid flow to enable safe and manageable shaft rotation. During normal pumping operations, the machine returns to high-speed operation. The controller dynamically switches between these modes based on operational requirements.
Solution Approach 2:
The fluid working machine alternates between different operational states: normal high-speed pumping operation and low-speed motoring operation for maintenance. The periodic switching between these modes allows the system to maintain high productivity during normal operation while enabling ease of operation during maintenance periods.
3Power
If high pressure fluid is supplied to working chambers to rotate the shaft, then external torque is not needed, but the pressure differential control becomes more challenging
Solution Approach 1:
The secondary high pressure manifold acts as an intermediary between the high pressure fluid source and the working chambers. It provides a controlled interface that allows high pressure fluid to be supplied to the working chambers without requiring complex pressure control mechanisms in the main system. The manifold serves as a buffer and distribution point that simplifies the overall pressure control architecture.
Data Source
AI summary
A fluid working machine comprising a controller and a working chamber, an electronically controllable low pressure valve associated therewith and a fast high pressure valve associated therewith, characterized in that the working chamber has associated therewith a slow high pressure valve for controlling the connection of the working chamber to a secondary high pressure manifold. A fluid working machine according to the invention may be operated to rotate its shaft to a certain position, for example to allow easy maintenance of a wind turbine generator.