Passive Air Bleed for Electric Vehicle Cooling Systems
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Solution Overview
Problem
Conventional liquid cooling systems face inefficiencies due to air entrapment at the liquid-to-air interface, which impairs liquid flow and reduces heat transfer effectiveness, especially when component packaging constraints prevent air from being easily removed, leading to trapped air pockets that degrade cooling performance.
Innovation Solution
The implementation of a passive air bleed system within the manifold, utilizing a pressure differential created by fluid flow to draw out accumulated air, either internally or externally, ensuring continuous removal of air without the need for active components, thus maintaining optimal liquid flow and heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If air removal pathways are added to the cooling system, then air accumulation is prevented, but device complexity increases
Solution Approach 1:
The invention extracts the air removal function from the main coolant flow path by creating a separate bleed pathway. The bleed port is positioned at a high point in the manifold where air naturally accumulates, allowing air to be extracted and removed separately from the primary cooling circuit without interfering with the main coolant flow.
Solution Approach 2:
The invention introduces an intermediary mechanism (the bleed port with reservoir) that mediates between the air accumulation problem in the manifold and the air removal solution. The reservoir acts as an intermediate chamber that collects air from the bleed port and allows it to be safely vented or returned to the system without disrupting the main cooling function.
2Volume of moving object
If component packaging constraints are maintained, then space is optimized, but air removal becomes difficult
Solution Approach 1:
The invention applies local quality by positioning the bleed port specifically at a high point in the manifold where air accumulation occurs most severely. This localized approach targets the specific problem area (air pockets at high points) without requiring system-wide redesign or additional space, maintaining compact packaging while solving the air removal issue where it is most critical.
3Shape
If coolant inlets and outlets are positioned at the bottom, then packaging is optimized, but air pockets form at the top
Solution Approach 1:
The invention extracts the air removal function from the bottom-mounted inlet/outlet configuration by adding a separate high-point bleed port. This allows the coolant lines to remain optimized at the bottom for packaging purposes while the bleed port, positioned at the top, extracts and removes air pockets that form due to the bottom-mounted configuration.
Solution Approach 2:
The bleed port serves as an intermediary element that bridges the conflict between bottom-mounted coolant lines (for packaging optimization) and top-accumulated air pockets (harmful factor). It provides a dedicated pathway that allows air to be removed from the high point without requiring the coolant inlets or outlets to be repositioned.
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 solution effectively prevents air accumulation, enhancing cooling efficiency by ensuring continuous air removal, even in designs where air pockets would typically form, thereby maintaining consistent temperature regulation and preventing hot spots.
Implementation Method 1
liquid coolant heat exchanger encompasses mechanisms that use a liquid fluid to promote heat transfer from one set of components of a system to another set of components
Implementation Method 2
The thermal impedance is adversely affected when movement of the liquid is impaired or when the liquid does not directly contact the interface
Implementation Method 3
utilizing a pressure differential created by fluid flow to draw out accumulated air
Implementation Method 4
The buoyancy of the air causes it to rise and accumulate
Data Source
AI summary
An electric vehicle drive unit includes an inverter, a gear box, an electric motor coupled to the inverter and to the gear box, a cooling jacket, and coupled to the gear box, a main coolant inlet, a coolant outlet, and an external passive air bleed device. The cooling jacket has a cooling chamber and surrounds at least a portion of the electric motor. The main coolant inlet couples to the cooling jacket. The coolant outlet is located at a lower portion of the gear box. The external passive air bleed device runs between an upper portion of the cooling jacket and the coolant outlet. The inverter may couple to a first side of the gear box and the electric motor may couple to a second side of the gear box such that the inverter and the electric motor reside on opposite sides of the gear box.