CASE STUDY: U-Shin Robustly Designs New Generation of Automotive Latches

The automobile industry’s increasing adoption of electronically controlled latch mechanisms is challenging engineers to adapt designs to meet new requirements. For example, U-Shin was recently asked to add an electronic microswitch to an existing mechanical trunk latch without changing the latch’s size.

To squeeze in the added electronics, the engineers needed to shrink the mechanism part of the latch while ensuring that the forces for opening and closing it still met functional requirements. They needed to take into account the effects of levers, cams, and tolerances on those forces, which are complex to model.

Creating a robust design that considers the variances of all the components individually and combined is critical to maintaining a latch’s performance to requirements.

Prior to U-Shin’s use of Enventive Concept for tolerance analysis, which began over ten years ago, their engineers typically used Excel spreadsheets for one-dimensional stackup analysis.

While they could do one part of the analysis on a single sheet, there could easily be ten parts to do across ten sheets which is very difficult to manage and time consuming. The spreadsheets also missed the global picture of connected lever and cam components and lacked precision in the analysis results.

The engineers found that Excel spreadsheets for tolerance analysis are like having basic, low-definition images of reality when high definition is what is needed.

Using Concept for their trunk latch redesign project, the engineers created an intuitive end-to-end visual model of the resized mechanism part of the latch including its kinematic chain and internal forces. The model precisely showed what happens visually and quantitatively from the input of a force all the way to its output.

The engineers were able to quickly iterate design parameters, such as geometries or tolerances, in either the visual model or via reports. With each iteration they immediately saw the impacts on the latch mechanism’s ability to meet its functional requirements.

The engineers were analyzing and designing with high-definition models. The result was rapid decision making at high levels of confidence.

With Concept, U-Shin finds that they dramatically cut the time to finalize a robust design with their 3D modeling software that is ready for manufacturing, which means that products can get to market more quickly. For instance with the trunk latch project U-Shin’s engineers completed their redesign within five days. The old spreadsheet way would have typically taken four weeks.

Concept’s high-definition modeling and analysis also enable fewer prototypes for projects like the trunk latch – typically one or two versus eight to ten using a spreadsheet.

With a faster time to market, reduced engineering design effort, and lower prototyping costs, U-Shin’s payback for using Concept is essentially immediate.

As the automotive industry moves to a next generation of electronically controlled latch mechanisms, such as for doors, trunks, rear hatches, fuel lids, and hoods, robustly designing to new functional requirements will be even more critical than with the current generation of mechanical-only latches. One example of such a requirement will be lower forces within electronically-actuated door latches to minimize battery drain and for safe opening.

With Enventive Concept, U-Shin’s designers have a proven tolerance analysis tool that will enable them to rapidly and confidently bring to market their next-generation products.