Universal Driveshaft Assembly With Curved Torque Keys for Wear Resistance

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Solution Overview

Problem

Conventional universal joints in driveshafts used in downhole motors for oil and gas drilling operations experience substantial wear and failure due to point or line contact, which disperses force over a small surface area, leading to accelerated wear.

Innovation Solution

A driveshaft assembly with a torque transfer assembly that utilizes a combination of planar and convex surfaces on torque transfer keys and an adapter, allowing for direct face-to-face engagement and torque transfer, reducing wear by distributing force more evenly across larger contact surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional universal joints use point or line contact for torque transfer, then the device complexity is reduced, but the wear resistance deteriorates due to force dispersion over small surface area

Engineering Contradiction:

Improvewear resistanceVSAvoidcontact surface geometry

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention employs spherical contact surfaces on the torque transfer keys and corresponding recesses in the driveshaft and end housing. This curvature allows for face-to-face engagement that distributes contact forces across larger surface areas, reducing wear while maintaining universal joint functionality. The spherical geometry enables the keys to rotate and pivot while maintaining consistent surface contact.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Duration of action of moving object

If conventional universal joints use simple contact surfaces, then the manufacturing precision requirement is reduced, but the operational life deteriorates due to accelerated wear from poor force distribution

Engineering Contradiction:

Improveoperational lifeVSAvoidsurface contact geometry

Core Design Contradiction:

Duration of action of moving objectVSManufacturing precision

Solution Approach 1:

The spherical contact surfaces provide inherent self-alignment and load distribution capabilities that extend operational life. The curved surfaces naturally accommodate misalignments and distribute forces evenly during rotation and pivoting, reducing wear accumulation and extending the service life of the driveshaft assembly.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Reliability

If conventional universal joints use point or line contact, then the device complexity is simplified, but the reliability deteriorates due to substantial wear and failure

Engineering Contradiction:

Improvefailure resistanceVSAvoidtorque transfer assembly

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The torque transfer function is segmented into multiple torque transfer keys distributed around the driveshaft circumference. Each key provides independent face-to-face contact with corresponding recesses, distributing the torque transfer load across multiple contact points. This segmentation enhances reliability by preventing single-point failure and reducing wear on individual contact surfaces.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The spherical contact surfaces on each torque transfer key enable face-to-face engagement that distributes forces across larger surface areas, reducing wear and preventing failure. The curved geometry allows the keys to accommodate universal joint rotation and pivoting while maintaining consistent surface contact, thereby improving failure resistance.

Inventive Principle:

Principle #14Spheroidality (Curvature)

4Reliability

If conventional universal joints use simple contact surfaces, then the ease of manufacture is improved, but the wear resistance deteriorates due to force dispersion over small area

Engineering Contradiction:

Improvewear resistanceVSAvoidcontact surface fabrication

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

While spherical surfaces require more complex manufacturing than flat surfaces, modern machining techniques can efficiently produce spherical contact surfaces. The curvature provides inherent load distribution that compensates for minor manufacturing variations, maintaining wear resistance even with reasonable tolerances. The spherical geometry can be achieved through standard turning and grinding operations.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

Dividing the torque transfer function into multiple segmented keys with spherical contact surfaces distributes the manufacturing complexity across several identical components. This segmentation allows for standardized production of each key, simplifying the overall manufacturing process while achieving the wear resistance benefits of spherical contact surfaces.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS11035415B2Universal driveshaft assembly

Publication Date: 2021.06.15 NAT OILWELL VARCO LP

AI summary

A driveshaft assembly includes a driveshaft including a longitudinal shaft axis, a first end, a second end, and a radially outer surface. The first end includes a plurality of recesses extending radially inward from the radially outer surface. The recesses each include a convex engagement surface. The driveshaft assembly also includes a first end housing including a longitudinal housing axis and an axially extending receptacle. The receptacle includes a plurality of planar receptacle surfaces. In addition, the driveshaft assembly includes a plurality of torque transfer keys configured to transfer torque between the driveshaft and first end housing. Each of the torque transfer keys includes a planar key surface and a concave key surface. The convex engagement surface of each recess engages the concave key surface of one of the torque transfer keys. The planar key surface of each torque transfer key engages one of the planar receptacle surfaces.