Motor Cooling Channel Layout for Balanced Flow and Pressure Loss

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Solution Overview

Problem

Existing motor units with unequal path lengths in coolant channels experience imbalanced flow rates and cooling capacities, leading to uneven cooling and the need for larger pumping systems.

Innovation Solution

The motor unit design includes coolant channels with varying cross-sectional areas, where the first channel has a larger cross-sectional area than the second channel, reducing pressure loss and adjusting flow rates to balance cooling capacity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If the path length of the first channel is made longer than the second channel, then the cooling coverage is improved, but the pressure loss increases and flow rate balance is disrupted

Engineering Contradiction:
Improvecooling coverageVSAvoidpressure loss
Core Design Contradiction:
Area of stationary objectVSLoss of energy

Solution Approach 1:

The patent applies local quality by making the cross-sectional area of straight portions in the first channel larger than in the second channel. This creates a non-uniform structure where different sections have different properties (cross-sectional areas) to compensate for the longer path length, thereby reducing pressure loss while maintaining cooling coverage.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes the parameter of cross-sectional area to resolve the contradiction. By increasing the cross-sectional area of straight portions in the first channel, the flow resistance is reduced, which compensates for the longer path length and maintains flow rate balance between channels.

Inventive Principle:
Principle #35Parameter changes

2Loss of energy

If the cross-sectional area of straight portions in the first channel is increased, then the pressure loss is reduced, but the manufacturing complexity increases

Engineering Contradiction:
Improvepressure lossVSAvoidmanufacturing complexity
Core Design Contradiction:
Loss of energyVSEase of manufacture

Solution Approach 1:

The patent segments the channel into straight portions and bent portions, applying different cross-sectional area characteristics to different segments. The straight portions have larger cross-sectional areas to reduce pressure loss, while the bent portions maintain consistent dimensions, simplifying the manufacturing approach by localizing the dimensional variation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by varying the cross-sectional area only in specific regions (straight portions) rather than throughout the entire channel. This localized approach reduces pressure loss where needed while maintaining manufacturing simplicity in other areas.

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

This design ensures uniform cooling of the motor, reduces the need for oversized pumps, and optimizes manufacturing efficiency by minimizing additional processing steps.

Implementation Method 1

The cross-sectional area of the straight portions of the first channel is larger than a cross-sectional area of the straight portions of the second channel. Accordingly, pressure loss can be reduced in the first flow passage

Methodology Applied
Scientific EffectPressure loss reduction through cross-sectional area variation: Bernoulli Effect

Implementation Method 2

a coolant channel that is provided in a wall face of the housing and that is configured such that a coolant flows through

Methodology Applied
Scientific EffectThermal convection: Convection

Data Source

PatentEP4583376A1Motor unit
Publication Date: 2025.07.09 TOYOTA JIDOSHA KK
  • EP4583376A1 patent drawingFigure 1
  • EP4583376A1 patent drawingFigure 2
  • EP4583376A1 patent drawingFigure 3

AI summary

A motor unit (1) includes a motor (2), a housing (30) that houses the motor (2), and a coolant channel (40). The coolant channel (40) includes an inlet passage (41), a branching passage (42) that is connected to the inlet passage (41) and into which a coolant flows from the inlet passage (41), a first channel (43) that is connected to the branching passage (42), and a second channel (44) that is connected to the branching passage (42) and also of which a path length is shorter than that of the first channel (43). The first channel (43) and the second channel (44) are each structured such that a plurality of straight portions is connected in series by a plurality of bent portions, and a cross-sectional area of the straight portions of the first channel (43) is larger than a cross-sectional area of the straight portions of the second channel (44).