Vehicle Coolant Flow Switching for Air Bubble Bleeding

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Solution Overview

Problem

In vehicles with complex coolant circuits, certain flow passages uncoupled from the reserve tank tend to form air bubbles, leading to pump deterioration and overspeed rotation due to increased air volume in the heat medium.

Innovation Solution

A heat management system with a switching device that couples and uncouples flow passages based on vehicle conditions, allowing air bleeding when stationary and separate heat management when traveling, reducing air bubbles by connecting to a reserve tank when necessary.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the first flow passage is uncoupled from the reserve tank to enable separate heat management, then heat management efficiency is improved, but air bubbles form and accumulate in the heat medium

Engineering Contradiction:
Improveheat management efficiencyVSAvoidpump operation reliability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The system performs air bleeding of the heat medium in advance by coupling the first flow passage to the reserve tank when the vehicle is stationary, before the pump operation begins. This preliminary air removal prevents air bubble accumulation during subsequent heat management operations, resolving the contradiction between separate heat management and pump reliability.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If the first flow passage is coupled to the reserve tank for air bleeding, then air bubbles are removed from the heat medium, but separate heat management becomes difficult

Engineering Contradiction:
Improveheat medium qualityVSAvoidheat management flexibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The switching device dynamically couples or uncouples the first flow passage from the reserve tank based on vehicle operation conditions. When the vehicle is stationary, the passage is coupled for air bleeding; when the vehicle is traveling, it is uncoupled for separate heat management. This dynamic switching resolves the contradiction between air bleeding and heat management flexibility.

Inventive Principle:
Principle #15Dynamics

3Reliability

If the switching device frequently switches between coupling and uncoupling states, then air bubbles are effectively removed, but system complexity and switching wear increase

Engineering Contradiction:
Improveair bleeding effectivenessVSAvoidswitching control complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system performs air bleeding periodically when the vehicle is stationary, rather than continuously switching during operation. The switching device couples the first flow passage to the reserve tank during stationary periods for air bleeding, then uncouples it for heat management during traveling. This periodic action pattern reduces switching frequency and system complexity while maintaining air bleeding effectiveness.

Inventive Principle:
Principle #19Periodic action

Data Source

PatentEP4635763A1Heat management system and vehicle
Publication Date: 2025.10.22 TOYOTA JIDOSHA KK
  • EP4635763A1 patent drawingFigure 1
  • EP4635763A1 patent drawingFigure 2
  • EP4635763A1 patent drawingFigure 3

AI summary

A heat management system is configured to perform heat management of a vehicle (10) using a heat medium. The heat management system includes: a first flow passage in which a reserve tank is not provided; a second flow passage in which a reserve tank (162) is provided; a switching device (180) configured to switch between coupling and uncoupling of the first flow passage and the second flow passage to and from each other; and a control device configured to control the switching device. The control device is configured to, when coupling conditions including that the vehicle (10) is stationary are met, make the heat medium flow through the first flow passage and the second flow passage that have been coupled to each other by the switching device.