Introduction
A seat is an assembly of metal structure, foam, plastic, trim, headrest and safety belt which is bolted to the vehicle Body_in_White(BIW) designed to accommodate and secure one adult occupant.
Primary function of the seat system is to secure Occupant in the seat in the case of Collision such as frontal and rear crash keeping occupant in airbag protection area and to give comfortable seating experience for driver and passenger at long traveling journeys, Secure occupant in seat while right and left-hand turns and to keep Paasenger safe from luggage impact.
In this Article, we are going to learn the fundamentals of automotive seat systems; to make it easy to understand I have divided content into below sections:
- Basics of seat systems – Purpose of seats, seat sub-systems, Different seat row configuration and Different types of automotive seats.
- Technical Terminologies like R/H point of seats, Torso angle, Thigh angle which are related to seats.
- Basic and Premium Adjustments like Length adjustment, Height Adjustment, Lumbar support, seat heating and vibration, Recliner adjustment and other comfort functions
- Homologation standards – Introduction to regulations such as ECE and FMVSS applicable to automotive seats.
- Seat-level validation tests – Seat belt anchorage test, luggage retention test, and other important seat safety tests.
Basics of seat system
1. Purpose of seat
If we talk about a car, it consists of multiple sub systems such as engine, interior, exterior, drive and traction, breaking, door closer and seat system. Among these, the seat system is the only sub-system that remains in continuous contact with the occupant throughout the journey, making it one of the most important systems for both comfort and safety.
There are several factors to consider when selecting a car, and one of the most important is its seating capacity. Vehicles are commonly classified as 2-seater, 5-seater, 6-seater, or 7-seater. They can also be identified by the number of seat rows, such as two-row or three-row vehicles. To understand the purpose of an automotive seat system, let’s first look at the following key functions.
Occupant Safety
As we know when an OEM want to launch a car in any region, it must comply with the safety regulations applicable to that region. This requirement is also consisting of frontal/ Rear crash, Rollover, Side impact and other important tests. In all of these test seat system plays important role as it partnered with seat belt and Air bag to protect the occupant from hazardous situation.
The seat system contributes to occupant safety in the following ways.
- During an accident or sudden breaking, the human body tend to move due to inertia. This can cause critical body parts to strike on IP panel, dashboarding, steering or other interior components, resulting in serious injuries or fatalities. The seat system helps controlling this movement by supporting occupant through cushion and backrest pan by supporting your hip, back and head area as it transfers inertia forces to BIW with the help of seat belt, Rails and headrest.
- The seat system secure occupant at correct place so occupant always be in position where occupant remains within the effective airbag protection zone during a collision. This allows the airbags to provide maximum protection and reduces the risk of severe injuries.
- In the case of a luggage retention test, or during a real-life frontal or rear-end collision, luggage stored in the boot space tends to move forward due to inertia. The second-row seat is designed to resist this luggage impact and prevent the impact forces from reaching the occupants seated in the rear row.
Occupant Comfort
Occupant comfort and the overall travel experience are primarily provided by seat system and its various features such as length adjustment, height adjustment, recliner even some premium cars have heating, ventilation and massage function which enhances comfort and driving in long journey. The below points explain how seat system helps with occupant’s comfort.
- For comfort seat has Foam and trim which do not allow contact with seat structure parts. Every car has backrest and cushion which are designed considering the comfort surfaces which are based on ergonomic study. Appropriate metal-to-body clearances are also maintained to ensure that occupants do not come into contact with structural metal components during normal seating conditions.
- While driving on winding or mountainous roads, the occupant tends to move sideways due to vehicle cornering. Seat bolsters are provided to support the occupant and reduce lateral body movement, thereby improving comfort and stability during turns.
- The seat cushion pan is designed to support the occupant during braking by transferring the inertial loads through the seat structure, reducing the tendency of the occupant to slide forward.
- Most premium vehicles are equipped with heating mats that keep the seat warm during cold weather. Ventilation systems improve airflow between the seat and the occupant’s body, while massage functions help reduce fatigue during long-distance driving.
Seat Sub Systems
Automotive seating system is combination of foam, trim, plastic , wire harness , headrest, seat belt accesories which have distinct propose but combined aim to give comfort, safety with power and manual control.
- Foam – Foam is the soft material which deforms as per human body and regain its shape when load is removed. So foam play a vital role considering the comfort while long journey. Foam are designed Considering comfort surface, minimums wall thickness, Meet to metal distance from the metal and to meet H point requirements.
- Trim – Trim or lether covers foam , metal to give aesthetic look also it plays a role as a Joint of foam to metal structure.