Electric Motor Parking Torque Control to Prevent Sprag Damage

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Solution Overview

Problem

The existing parking systems in vehicles equipped with electric motors face damage to mechanical axle-fixing devices when the parking range is selected under specific conditions, such as vehicle inclination or creep torque, leading to potential discomfort and anxiety for the driver due to vibrations and shocks.

Innovation Solution

A parking control method for vehicles with electric motors that calculates and controls the output torque to stop the vehicle before engaging the driving shaft, using sensors to detect vehicle state and apply torque compensation to prevent damage, ensuring the vehicle is fully stopped before mechanical fixation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the parking range is selected when the vehicle is moving at low speed (e.g., 2.5 kph or lower), then the parking sprag can be engaged with the parking gear to fix the driving shaft, but the parking sprag may be damaged due to applied load from vehicle inclination, inertia, or creep torque of the electric motor

Engineering Contradiction:

ImproveParking operation speedVSAvoidParking sprag durability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The controller applies creep torque control to the electric motor before engaging the parking sprag with the parking gear. This preliminary action reduces the vehicle speed to substantially zero and minimizes the load on the parking sprag before mechanical engagement occurs, preventing damage while maintaining efficient parking operation

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces purely mechanical engagement of the parking sprag with a controlled electrical torque application first. The electric motor's creep torque control substitutes for mechanical braking or friction-based slowing methods, providing precise speed reduction and load management before the mechanical parking engagement

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Loss of time

If the parking range is selected when the vehicle is moving at low speed, then the parking process is completed quickly, but vibration and shock are generated in the vehicle causing discomfort and anxiety to the driver

Engineering Contradiction:

ImproveParking engagement timeVSAvoidVibration and shock

Core Design Contradiction:

Loss of timeVSObject-affected harmful factors

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The electric motor applies counter-torque through creep torque control to offset the vehicle's momentum and inclination forces before parking engagement. This preliminary anti-action prevents the generation of harmful vibrations and shocks during the parking sprag engagement by neutralizing the forces that would otherwise cause driver discomfort

Inventive Principle:

Principle #9Preliminary anti-action

Data Source

PatentUS10981555B2Vehicle equipped with electric motor and parking control method therefor

Publication Date: 2021.04.20 HYUNDAI MOTOR CO LTD

AI summary

Disclosed are a vehicle equipped with an electric motor, which is capable of preventing damage to a mechanical axle-fixing device when a parking range is selected under a specific condition, and a parking control method therefore. The parking control method includes calculating output torque of the electric motor to stop the vehicle when a parking (P) range is selected in the situation in which a specific condition is satisfied, controlling the electric motor in response to the output torque, and activating a driving shaft fixing unit when the vehicle is stopped by the controlling.