Motor Torque Control for Universal Joint Speed Mismatch

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Solution Overview

Problem

Universal joints in electric vehicle axles experience mismatched rotational speeds between input and output shafts due to bending, leading to vibrations and shuddering, and existing solutions like constant velocity joints increase complexity and cost.

Innovation Solution

A method for controlling motor torque by determining the motion of universal joints and adjusting the speed of the motor based on the speed differential across these joints, using a control system to match the speed of the motor with the front axle.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If constant velocity joints are used to eliminate speed mismatch, then vibration and shuddering are reduced, but device complexity and manufacturing cost increase

Engineering Contradiction:

Improvevibration and shudderingVSAvoiddevice complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical solution of using constant velocity joints with a control system that uses sensors to detect universal joint motion and a motor controller to adjust motor speed accordingly. This substitutes a complex mechanical joint with a simpler universal joint plus electronic control, reducing device complexity while maintaining vibration reduction.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent dynamically changes the motor speed parameter based on detected universal joint motion. By adjusting the motor speed to match the output shaft speed of the universal joint, the system compensates for speed mismatch and eliminates vibration without requiring complex mechanical joints.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If constant velocity joints are used to eliminate speed mismatch, then vibration and shuddering are reduced, but manufacturing cost increases

Engineering Contradiction:

Improvevibration and shudderingVSAvoidmanufacturing cost

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent replaces expensive constant velocity joints with a simpler universal joint combined with an electronic control system. The control system detects universal joint motion and adjusts motor speed to compensate, achieving the same vibration reduction effect at lower manufacturing cost.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses a standard, inexpensive universal joint instead of a costly constant velocity joint. While the universal joint has inherent speed mismatch, the system compensates using affordable electronic sensors and control algorithms, achieving cost-effective vibration elimination.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Object-affected harmful factors

If hub lock or transfer case disconnect devices are used, then speed mismatch is eliminated, but device complexity increases

Engineering Contradiction:

Improvespeed mismatchVSAvoiddevice complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent replaces mechanical disconnect devices like hub locks and transfer cases with an electronic control system. The control system continuously monitors universal joint motion and adjusts motor speed in real-time, eliminating speed mismatch without requiring mechanical disconnection mechanisms.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses dynamic speed adjustment of the motor based on real-time detection of universal joint motion. This dynamic control approach continuously adapts motor speed to match the output shaft speed, providing ongoing compensation without mechanical disconnects.

Inventive Principle:

Principle #15Dynamics

4Ease of manufacture

If universal joints are used instead of constant velocity joints, then manufacturing cost is reduced, but speed mismatch causes vibration and shuddering

Engineering Contradiction:

Improvemanufacturing costVSAvoidvibration and shuddering

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent keeps the simple, inexpensive universal joint but adds an electronic control system that detects its motion and compensates for speed mismatch. This substitution of control methodology eliminates vibration while maintaining the cost advantages of universal joints.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent implements a feedback control system where sensors detect the motion of the universal joint and this information is fed back to the motor controller. The controller uses this feedback to adjust motor speed and compensate for speed mismatch, eliminating vibration while maintaining low cost.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS12434567B2Systems and methods for motor torque control for universal joint correction

Publication Date: 2025.10.07 DANA AUTOMOTIVE SYST GRP LLC

AI summary

Methods and systems are provided for operating a vehicle system, including determining a motion of a universal joint in a drive axle assembly of the vehicle system and adjusting a speed of a motor of the vehicle system based on the motion of the universal joint.