Balancing Disk Annular Groove for Motor Oil Scouring Control

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Solution Overview

Problem

Existing motor designs face issues with increased scouring force on the stator due to high-speed rotation, leading to damage and reduced service life of insulating materials, particularly at high rotating speeds.

Innovation Solution

A balancing disk with an oil discharge port and annular groove design that disperses oil into a film, reducing the scouring force by atomizing and spraying it towards the stator root, while maintaining effective cooling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If high-speed rotation is used to improve cooling efficiency, then cooling effect is improved, but scouring force on stator increases causing damage to insulating materials

Engineering Contradiction:

Improvecooling effectVSAvoidscouring force on stator

Core Design Contradiction:

TemperatureVSObject-affected harmful factors

Solution Approach 1:

The oil discharge port is divided into multiple segments (first oil discharge port, second oil discharge port, etc.) arranged circumferentially, and the oil film is segmented into multiple sections by partition walls. This segmentation reduces the concentrated scouring force on any single point of the stator while maintaining overall cooling effectiveness through distributed oil delivery.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the balancing disk are designed with different oil discharge characteristics. The oil discharge ports are positioned and sized differently to create localized oil spray patterns that optimize cooling in specific areas while controlling scouring forces. The partition walls create localized oil film sections with different flow characteristics.

Inventive Principle:

Principle #3Local quality

2Quantity of substance

If oil discharge port size is increased to improve oil flow and cooling, then cooling efficiency is improved, but scouring force on stator increases

Engineering Contradiction:

Improveoil flowVSAvoidscouring force on stator

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The total oil flow requirement is divided across multiple smaller oil discharge ports instead of one large port. Each port delivers a portion of the total oil flow, creating multiple smaller oil streams that are less scouring than a single large stream, while collectively providing sufficient cooling oil quantity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The oil discharge is transformed from a concentrated axial spray into a distributed radial oil film through the annular groove and partition walls. This dimensional change from point-source spray to surface film reduces the intensity of scouring force while maintaining oil delivery quantity for effective cooling.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Temperature

If rotating speed is increased to improve cooling performance, then cooling performance is improved, but service life of insulating materials decreases

Engineering Contradiction:

Improvecooling performanceVSAvoidservice life of insulating materials

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The oil delivery system is segmented into multiple discharge ports and film sections that distribute cooling oil across different locations. This segmentation allows the system to operate at higher rotating speeds with reduced localized scouring forces, protecting insulating materials while maintaining cooling performance through distributed oil delivery.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The annular groove and partition walls act as intermediaries that transform the high-velocity oil jet into a distributed oil film. This intermediary structure reduces the direct impact and scouring force on the stator and insulating materials while maintaining the cooling effect, enabling higher operating speeds without damage.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

The design prolongs the service life of the motor by protecting insulating materials and allowing for higher rotating speeds without stator damage, improving NVH performance and cooling efficiency.

Implementation Method 1

The oil discharge port is communicated with the first end face and the annular groove, to enable oil flowing out of the oil discharge port to be discharged through the annular groove

Methodology Applied

Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 2

the oil is sprayed to a stator winding from a balancing disk through an oil path formed by the balancing disk and an iron core, to complete cooling of the rotor assembly

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 3

hot spot direct cooling is realized

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Data Source

PatentEP4465496B1Balancing disk for motor, rotor assembly, motor and vehicle

Publication Date: 2026.01.28 XIAOMI EV TECH CO LTD

Figure 1
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AI summary

A balancing disk (10) has an oil discharge port (13), and a first end face and a second end face (12) opposite to each other; the first end face is configured to fit on an end face of a rotor core, the second end face (12) has an annular groove (14), and the oil discharge port (13) is communicated with the first end face and the annular groove (14), to enable oil flowing out of the oil discharge port (13) to be discharged through the annular groove (14).