Axial Piston Drive Shaft Geometry for Higher Torque Through Drive
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Solution Overview
Problem
Axial piston machines with swashplate design have a second shaft end that is thinner and weaker due to an undercut, limiting the torque transmission capacity compared to the first shaft end.
Innovation Solution
The design includes a drive shaft with a non-rotating swashplate, a cylinder drum coupled to the central region, and a compression spring that clamps the cylinder drum against a distributor plate. A concave rounded portion on the drive shaft increases the diameter, supporting the second rolling bearing and eliminating the notch effect of the undercut, allowing for thicker and stronger end portions to transmit increased torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the second shaft end is designed with a thinner diameter to accommodate the rolling bearing, then the bearing can be properly supported, but the torque transmission capacity is reduced
Solution Approach 1:
The patent applies a concave rounded portion (spheroidal curvature) at the second shaft end instead of a traditional undercut. This rounded geometry with a large radius eliminates stress concentration while providing adequate bearing support surface, thereby maintaining both bearing reliability and torque transmission capacity without requiring shaft thinning
2Reliability
If an undercut is configured on the internal periphery to support the rolling bearing, then the bearing can be mounted, but the shaft strength is weakened due to the notch effect
Solution Approach 1:
The patent converts the potentially harmful undercut geometry into a beneficial concave rounded portion. This rounded geometry eliminates the notch effect and stress concentration that would weaken the shaft, while still providing the necessary bearing support surface. The harmful sharp transition is transformed into a beneficial smooth curvature that enhances both strength and bearing mounting capability
3Strength
If the shaft diameter is increased to transmit more torque, then the torque transmission capacity improves, but the bearing support structure becomes more complex
Solution Approach 1:
The patent applies local quality by creating a concave rounded portion only at the specific location where the second rolling bearing is mounted, rather than increasing the entire shaft diameter. This localized geometric modification provides the necessary bearing support surface and eliminates stress concentration only where needed, maintaining torque transmission capacity without unnecessarily increasing overall shaft complexity or size
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
This configuration enhances torque transmission on the second shaft end, enabling the axial piston machine to handle greater mechanical loads and improve overall performance by distributing the load more evenly and increasing the strength of the drive shaft.
Implementation Method 1
A compression spring is arranged between the drive shaft, in particular the central region, and the cylinder drum, via which compression spring the cylinder drum is clamped against a distributor plate
Implementation Method 2
a second rolling bearing and a second coupling device are provided on an end portion of the drive shaft on the distributor plate side
Data Source
AI summary
A hydrostatic axial piston machine has a drive shaft penetrating a housing on either side. In this case, the mechanically weaker of the two shaft ends is strengthened by an undercut being eliminated, said undercut defining the minimum diameter of the shaft end and thus of the entire drive shaft. Instead, the strength of the relevant shaft end is increased by a displacement of a circular bearing surface for a rolling bearing radially outwardly and away from the rolling bearing. In this case, the circular bearing surface is displaced below a compression spring which clamps the cylinder drum against a distributor plate. The resulting spacing between the circular bearing surface and the rolling bearing remaining in place is bridged by a sleeve or by a ring. A concave rounded shaft shoulder is simply formed below the sleeve and/or the ring.