Wobble Drive Axial Piston Engine Eliminates Side Forces
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Solution Overview
Problem
Axial piston steam engines with ball-jointed piston rods face issues of high manufacturing and maintenance costs, side pressure from angular piston rod alignment, and restricted gas flow due to confined spaces, limiting their scalability and commercial adoption.
Innovation Solution
A modular axial piston engine design with freely rotating and swiveling cylinders on hollow ball-swivel joints, using a wobble drive member with a central pivot point and tubular piston rod-guide for straight-line movement, reducing friction and lubrication needs, and allowing large valve ports for fluid exchange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If ball-jointed piston rods are used to convert piston motion into rotary movement, then rotary motion is achieved, but side pressures are generated against the pistons and connecting rods
Solution Approach 1:
Instead of using angular piston rods to convert linear motion to rotary motion (which creates side pressures), the patent inverts the approach by using a wobble plate that converts rotary motion back to linear piston motion. The wobble plate oscillates between parallel planes, maintaining perpendicular alignment with the cylinder axis and eliminating side forces on the pistons.
Solution Approach 2:
The wobble plate uses a spherical pivot point that allows the plate to oscillate between two parallel planes. This spherical geometry enables the conversion of rotary crankshaft motion into linear reciprocating piston motion without creating angular misalignment or side pressures on the piston rods.
2Strength
If multiple precisely machined parts and castings are used in the engine construction, then structural integrity is maintained, but manufacturing cost and complexity increase
Solution Approach 1:
The engine is divided into modular components: a stationary cylinder block, movable pistons with rods, a wobble plate mechanism, and a crankshaft assembly. This segmentation allows each component to be manufactured independently with standard machining processes, reducing overall manufacturing complexity while maintaining structural integrity through standardized connection interfaces.
Solution Approach 2:
The wobble plate serves multiple functions simultaneously: it converts rotary motion to linear motion, supports the piston rods, provides a mounting surface for the crankshaft connection, and maintains precise alignment through its spherical pivot. This multi-functionality reduces the number of separate components needed, lowering manufacturing cost.
3Power
If ball-jointed piston rods with extensions and seals are used, then rotary motion is achieved, but lubrication requirements increase and maintenance becomes difficult
Solution Approach 1:
The harmful ball-jointed connecting rods are extracted from the system and replaced with a wobble plate mechanism. This eliminates the need for complex joints, extensions, and seals in the piston rod assembly, thereby removing the lubrication and maintenance problems associated with these components while preserving the rotary motion conversion function.
4Volume of moving object
If confined space is used for valve plumbing and actuation between cylinders, then engine compactness is achieved, but port openings are restricted and gas flow is limited
Solution Approach 1:
The valve plumbing and actuation mechanisms are relocated from the confined space between cylinders to the peripheral region around the cylinder bank. This dimensional relocation allows for larger port openings and more generous gas flow paths without increasing the overall engine footprint, as the valves are positioned in the radial direction rather than the axial direction.
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
The design reduces friction, minimizes lubrication requirements, and enables easy scalability, resulting in a lightweight, efficient, and cost-effective engine with improved power-to-weight ratio and reduced heat loss.
Implementation Method 1
a wobble drive member with a central pivot point established by a flexible rod or a universal joint on the crankshaft axis. The wobble drive member conveys the reciprocated movement of the piston disks to a single crank-pin pivotally connected at an angle to the axis of the crankshaft.
Implementation Method 2
a tubular piston rod-guide is centered in a bracket attached to the cylinders to procure alignment of the piston disks within cylinders
Implementation Method 3
The aforementioned ball-swivel joints pivotally connect the base of the cylinders to rotary valves that are provided to port fluid to and from the cylinders.
Data Source
AI summary
An axial piston fluid engine having single-acting cylinders incorporating swivel-joint attachment of the cylinders to rotary control valves wherein straight-line piston movement is established for the elimination of side forces on the pistons. The pistons and the control valves are operatively connected to a common wobble drive member and arranged in geometry of lever positions to coactively time the drive fluid into and out of the cylinders intermittently.