Hall-Effect Switched Seat Belt Buckle Assembly

Patent & Production

At a glance

What the claims cover, in plain language

Claim 1 - a safety belt buckle comprising a lock core assembly, upper cover shell, and lower cover shell. The shells enclose the core. A switch assembly with a Hall detection element is installed in the lower shell. A magnet assembly is attached to the lock core. When the latch tongue inserts, it drives the magnet assembly to reciprocate. In the locked position, the magnet aligns directly opposite the Hall element. The lock core includes a slot seat and an ejector part that moves with the tongue. The magnet assembly has a bracket and magnet held by an elastic piece. The switch assembly includes a PCBA with a Hall switch chip connected to the vehicle system. The PCBA is long-strip shaped, aligned with the magnet’s movement path, and fixed to the lower shell via a guide column and snap-in structures.

Claim 2 - specifies that the opening in the magnet bracket’s receiving cavity can be located at the top or side of the bracket.

This is a simplified reading for orientation only. The legal scope is defined by the exact claim wording in the official Chinese document.

What this means for US production

This patent was filed in China and is currently in force there. The public record shows no US or other foreign counterpart. Making or selling this specific configuration in China would require the owner’s permission.

Two points to settle early:

• Other patents may exist. Seat belt buckle electronics and Hall-effect sensing are common in automotive supplier portfolios globally. While this specific structural arrangement of a shell-mounted PCBA appears unique in the public record, a freedom-to-operate (FTO) review is recommended to check for broader US patents covering buckle-integrated sensors or similar magnet-alignment methods.
• Regulatory certification. Unlike consumer goods, automotive safety components face strict homologation requirements. Even if the patent does not restrict you, obtaining approval for mass-market vehicle installation involves significant testing beyond IP clearance.

Customization and manufacturing

What can be customized

Things to plan for (US market)

• FMVSS 209 - Federal Motor Vehicle Safety Standard for seat belt assemblies; requires rigorous dynamic testing.
• ISO 26262 - Functional safety standard for road vehicles; applies if the buckle feeds critical ADAS or airbag logic.
• SAE J1100 - Dimensions of motor vehicle occupant space; affects buckle placement and reach.
• EMC Compliance (FCC Part 15 / CISPR 25) - Electronic modules must not interfere with vehicle radios or other ECUs.

How a project runs

1. Inquiry - Define vehicle platform, connector specs, and detection logic requirements.
2. Design - Finalize shell geometry, PCBA footprint, and magnet trajectory simulation.
3. Prototype - 3D-printed housings and hand-soldered PCBAs for bench testing.
4. Validation - Environmental stress screening (ESS), vibration tests, and crash sled compatibility checks.
5. Production - Injection molding, SMT assembly, ultrasonic welding or screw assembly, and automated optical inspection (AOI).

Quantities & timeline

Tooling for injection-molded shells takes 12-16 weeks. PCBA prototyping runs parallel. Certification testing for automotive safety standards typically adds 6-9 months to the schedule. Send us your vehicle model, connector type, quantity, and target price and we will reply with options.

Production notes

Tooling and process

Injection molding is likely used for the upper and lower cover shells, requiring precision molds to ensure the snap-fit interfaces align correctly. The PCBA involves surface-mount technology (SMT) processes. Assembly typically combines mechanical fastening and adhesive bonding to secure the guide columns and snap structures.

Cost drivers

The primary cost factors are typically the mold complexity for the plastic shells and the grade of the Hall-effect IC. Magnet retention mechanisms and the specific packaging required for automotive-grade electronic components also influence the final unit cost.

Prototyping path

Initial samples can be created using 3D-printed housings and manually placed magnets to verify the alignment tolerance between the magnet assembly and the Hall sensor. Fit grading is essential to ensure the ejector part moves smoothly without binding against the shell.

What we would change before tooling

We would refine the wall thickness and joint design of the lower shell to prevent cracking during the snap-in of the PCBA. Ensuring the magnet bracket’s elastic shield maintains consistent pressure is critical before hard tooling begins.

Common failure points

Potential issues include spring fatigue in the magnet retention clip, leading to loose magnets. Hardware corrosion on the latch interface and size deviation in the mold could cause misalignment between the magnet and sensor, resulting in false lock signals.

Patent drawings

Drawings reproduced from the public patent document for reference.

Frequently asked questions

How does the buckle know if the belt is fastened?

It uses a Hall-effect sensor. When you insert the latch tongue, it mechanically moves a magnet assembly closer to the sensor. When the magnet aligns directly opposite the sensor, the electronic chip detects the magnetic field and sends a “locked” signal to the car’s computer. When released, the magnet moves away, and the signal changes to “unlocked.”

Why is the circuit board separate from the lock mechanism?

Separating the Printed Circuit Board Assembly (PCBA) into the lower shell prevents damage from the physical impact and vibration of the locking action. Mechanical switches often fail because they are part of the moving parts. Here, the sensor stays still while the magnet moves past it, improving long-term reliability.

Is it difficult to repair if the electronics fail?

No. Because the PCBA is snapped into the lower cover shell, you can access and replace the electronic module by removing the lower shell. You do not need to disassemble the complex lock core assembly, which saves time and reduces the risk of damaging the safety mechanism during repairs.

Does this work with all car systems?

The buckle outputs a standard electrical signal via wires. It must be compatible with the specific voltage and communication protocol of the vehicle’s body control module. Custom connectors or adapter harnesses may be needed depending on the car manufacturer.

Can it be used in commercial trucks?

Yes. The robust design handles higher vibration levels common in heavy machinery and trucks. However, commercial fleets should verify that the signal integration meets their telematics or safety monitoring software requirements.

What materials are used for the shells?

The patent describes cover shells that snap together. In production, these are typically made from high-impact engineering plastics like PA66 or ABS to withstand temperature extremes and physical stress. Metal variants are possible but require different tooling.

Can this design be made and sold in the US?

The patent is in force in China. The public record shows no US counterpart, so this specific patent does not restrict making or selling the design in the US. However, automotive safety components are subject to other global patents and strict federal regulations (FMVSS). We recommend a freedom-to-operate check and regulatory review before production.

Are you affiliated with the patent owner?

No. IP2M is an independent design and manufacturing service working from the public patent document.

Request a quote

Click Request a Quote below to see our email address - copy it, or open your email app with a ready-made message. Please mention patent CN111358122B in the subject.

Helpful details to include:

• Your company and channel (automotive supplier, EV manufacturer, aftermarket retrofit, industrial equipment maker)
• Vehicle platform or application type
• Connector specifications and signal requirements
• Quantity and target price
• Timeline - when you would like prototypes and validation samples

You can also reach us at (332) 203-9997.