Pivoting Surface Coating for Hydrostatic Axial Piston Machine Wear

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Solution Overview

Problem

The production of bent-axis hydrostatic axial piston machines with variable displacement volume is hindered by high production costs due to complex and costly heat treatment and hardening processes for the control base receptacle and sintering processes for non-ferrous metal layers on the cylinder drum, which increase wear but are inefficient.

Innovation Solution

Applying a wear-reducing hard material layer, such as a carbon-containing or chromium nitride layer, to the pivoting surface of the control base and control surface using physical vapor deposition (PVD) methods, eliminating the need for surface hardening and sintering processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If gas-nitriding heat treatment is applied to the control base mount receiving surface, then wear resistance is improved, but production cost and manufacturing complexity increase significantly

Engineering Contradiction:

Improvewear resistanceVSAvoidproduction cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies a wear-reducing hard material layer specifically to the pivoting surface of the control base, which is the local area experiencing wear. This selective coating approach provides wear protection exactly where needed without requiring expensive heat treatment of the entire control base mount receiving surface, thus resolving the contradiction between wear resistance and manufacturing cost.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Instead of applying the wear-reducing treatment to the large receiving surface of the control base mount (as in conventional approaches), the patent inverts the approach by coating the smaller pivoting surface of the control base itself. This reversal significantly reduces the area requiring treatment and the associated manufacturing costs while maintaining wear protection.

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If a wear-reducing hard material layer is applied to the pivoting surface of the control base, then wear resistance is improved, but manufacturing complexity increases due to additional coating process

Engineering Contradiction:

Improvewear resistanceVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent employs PVD coating technology, which is a more economical and less complex manufacturing process compared to gas-nitriding heat treatment. The PVD process can be applied selectively to the pivoting surface without requiring complex setup or extensive processing time, thus improving wear resistance while minimizing the increase in manufacturing complexity.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Stability of the object's composition

If the control base receptacle receiving surface is made larger to accommodate the control base, then stability is improved, but the area requiring expensive heat treatment increases

Engineering Contradiction:

ImprovestabilityVSAvoidproduction cost

Core Design Contradiction:

Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The patent shifts the wear protection from the large receiving surface of the control base receptacle to the smaller pivoting surface of the control base itself. This local quality approach ensures that the stable, large receiving surface does not require expensive heat treatment, while the smaller critical pivoting surface receives the wear-reducing hard material layer through PVD coating.

Inventive Principle:

Principle #3Local quality

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

Significantly reduces wear on the plain bearing surfaces while lowering manufacturing costs by simplifying the coating process and avoiding complex heat treatments and sintering processes, making the production of bent-axis machines more cost-effective.

Implementation Method 1

Methodology Applied

Scientific EffectPhysical vapor deposition: Physical Vapour Deposition

Data Source

PatentEP3093489B1Hydrostatic axial piston machine with inclined axes

Publication Date: 2022.12.07 LINDE HYDRAULICS

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AI summary

The invention relates to a hydrostatic axial piston machine (1) in a skewed-axis design with a drive shaft (4) rotatably arranged about a rotational axis (6) and provided with a drive flange (3), and a cylinder drum (7) rotatably arranged about a rotational axis (8), wherein the cylinder drum (7) is provided with several piston recesses (9) arranged concentrically to the rotational axis (8) of the cylinder drum (7), in each of which a piston (10) connected to the drive flange is arranged to be longitudinally displaceable, wherein the cylinder drum (7) rests against a control base (17) provided with a control surface (16), and wherein the axial piston machine (1) is designed as an adjustable machine with a variable displacement volume, wherein the control base (17) is arranged in a control base receptacle (2a) of the housing (2) with a pivoting surface (25) opposite the control surface (16) so as to be pivotable about a pivot axis (S).wherein a sliding bearing is formed between the pivoting surface (25) of the control base (17) and the control base receptacle (2a) of the housing (2). According to the invention, a wear-reducing hard material layer (30) is applied to the pivoting surface (25) of the control base (17).