Battery Cover Assembly Axial Insulation Tolerance
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Solution Overview
Problem
In hybrid electric vehicle batteries, manufacturing variations in cell lengths and connections lead to increased stackup tolerance, compromising the integrity of bus bar connections and requiring larger housings due to insulating sleeves, while temperature sensors are often damaged during assembly.
Innovation Solution
An end-to-end cell connection system with a conductive interconnector, washer-shaped insulator, and integrated temperature sensor receptacle reduces the battery assembly diameter and minimizes stackup tolerance, allowing for improved cooling and reduced sensor lead breakage by positioning sensors near the interconnector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If insulating sleeves are placed over cell connection points to prevent shorts, then electrical insulation is improved, but the battery housing diameter increases
Solution Approach 1:
The patent transitions from radial insulation (sleeves extending outward from cell connections) to axial insulation (insulator contained within the cell group diameter). The insulator is positioned between the conductive interconnector and cell, extending along the axial direction rather than radially, thereby preventing shorts without increasing housing diameter.
Solution Approach 2:
The insulator is nested within the existing cell group structure, specifically positioned between the conductive interconnector and the cell. This nested arrangement allows the insulator to provide electrical insulation while being contained within the existing diameter boundaries of the cell group, avoiding the need to increase housing size.
2Adaptability or versatility
If bus bars are forced to bend to accommodate cell group length variations, then adaptability to manufacturing tolerances is improved, but connection integrity deteriorates
Solution Approach 1:
The conductive interconnector acts as an intermediary component between cell groups, providing a rigid structural element that maintains connection integrity. Rather than forcing bus bars to bend, the interconnector absorbs length variations through its own design, serving as a mediator that prevents stress transmission to the bus bar connections.
Solution Approach 2:
The patent divides the connection system into separate functional components: the conductive interconnector handles mechanical alignment and length tolerance, while the bus bar focuses on electrical connection. This segmentation allows each component to be optimized for its specific function without compromising the other.
3Measurement precision
If temperature sensors are positioned deep within the battery assembly to monitor cell temperatures, then measurement accuracy is improved, but sensor lead damage risk increases during assembly
Solution Approach 1:
The temperature sensor is pre-positioned in a protected location (such as within the insulator or on the conductive interconnector) before final battery assembly. This preliminary positioning ensures the sensor is securely installed and protected from damage during subsequent assembly operations, while still maintaining its ability to accurately monitor cell temperatures.
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 solution reduces the battery assembly size, maintains connection integrity, and enhances cooling efficiency by accurately estimating internal cell temperatures without additional hardware, while preventing sensor damage during assembly.
Implementation Method 1
a washer-shaped insulator located between the conductive interconnector and the first cell. The insulator has an inside diameter large enough to slide over an exterior surface of the standoff portion
Implementation Method 2
an end-to-end cell connection system which has a conductive interconnector with: an inner ring portion welded to an end of a first cell; a standoff portion contiguous with the inner ring portion; and two tabs extending from the standoff portion. The two tabs are welded to an end of a second cell
Implementation Method 3
an inner ring portion welded to an end of a first cell; and two tabs extending from the standoff portion. The two tabs are welded to an end of a second cell
Data Source
AI summary
An end-to-end cell connection system for a battery assembly uses a conductive interconnector with an inner portion welded to an end of one cell, a standoff portion contiguous with the ring portion, tabs extending from the standoff portion, with the tabs welded to an end of another cell. By placing an insulator between the interconnector and the one cell, an electrical short is prevented in the event that a longitudinally coupled cell group is jostled. At the cell connections, there is a recess. To hold the cell group in place, the housing has a tab extending into the recess. The tab is at the center so that any dimensional variations are accommodated on each side of the tab. The interconnector also may include a receptacle for a thermistor to obtain a measure of battery assembly temperature. Diverter ribs may be provided in the housing to distribute flow to all cells.