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Honda Airbag Systems Follow a Unique Evolutionary Path Since the First for a Japanese Car

Airbag systems cushion the impact on seatbelt-wearing vehicle occupants in the event of a collision. Honda began airbag research in the 1970s and developed in 1987 a driver-side SRS airbag system for incorporation into the Legend, a first for a Japan-made vehicle. This independent development acknowledging real-world accident conditions continues as Honda seeks to bolster collision safety with features such as airbags for both front- and rear-seat occupants and to keep enhancing the effectiveness of systems.

The driver-side SRS airbag system incorporated into the Honda Legend in 1987 was a first for a Japan-made vehicle

Airbag Inflation Mechanism

Airbag Storage Structure (Driver-Side/Front Passenger-Side)

Airbag Actuation

(Front Passenger-Side Airbag Actuation Example)

Types of Honda Airbag Systems

Honda constantly strives for improvements in protection and impact mitigation performance by accumulating know-how through the examination of actual accidents and extensive simulation and crash testing.

* Inclusion of the various airbags differs according to the country or region

(1) Driver-Side and Front Passenger-Side i-SRS*¹ Airbag Systems

The optimal timing of airbag deployment for making contact with the vehicle occupant varies according to the collision speed and the manner of the collision. Honda therefore developed a dual inflator system that deploys airbags in two stages during low-speed collisions, but one quick step in high-speed collisions.
Honda also developed an internal pressure-retaining airbag that maintains sufficient internal pressure even in situations when more time is taken for the seat occupant to come into contact with the airbag, such as when the person has a large build. The vent flaps remain closed until the seat occupant comes into contact with the airbag, retaining the internal pressure for a long time for more effective occupant protection performance.

*1 The “i” in i-SRS reflects the idea of an “intelligent” system. “SRS” stands for “supplemental restraint system.”

For front passengers, who sit with varied posture, an airbag that inflates wider than the driver-side airbag is used. And to avoid injuries directly caused by the seat occupant coming into contact with the airbag as it is deployed, a top-mounted design is used. The airbag inflates upward, along the line of the windshield.

Front Passenger-Side Airbag Deployment

Honda has also developed a front passenger-side airbag system that mitigates the risk of brain damage in the event of an oblique collision.*² The airbag, when deployed, has three parts—a middle section and two sides. This allows the airbag to deploy across the entire space in front of the front passenger seat and suppress sideways movement of the head. Even in an oblique frontal collision when the lateral force of the impact causes the head to lurch sideways, the impact is cushioned. The head is protected, prevented from sliding off the airbag.

*2 Adopted for North American models from 2020

(2) Front and Rear Seat i-Side Airbag Systems*³

These airbag systems, built into the seats, are effective at cushioning the impact of a side collision on a seat occupant’s chest area. They are stored inside the outside ends of the seat backrests. Because vehicles have little room on the side of vehicle to absorb an impact, side airbags need to deploy quickly in the extremely narrow space between the seat occupant and door, at the same time avoiding any injury to the occupant inflicted during deployment. The airbags therefore have two layers—a high-pressure section that deploys instantly, and a low-pressure section that comes into contact with the seat occupant. This results in both faster deployment and effective cushioning of the impact on the occupant.

*3 Adopted for European, North American, and Chinese models from 2020

Side Airbag Structure

(3) Side Curtain Airbag System (for Front and Rear Seats, or First- to Third-Row Minivan Seats)

A side curtain airbag system protects the seat occupant’s head and neck in a side collision, preventing head impacts with the B-pillar or other parts of the vehicle. The airbag, which covers the side windows almost completely, deploys instantly, demonstrating excellent protection performance unaffected by the occupant’s build or sitting posture. The airbag deploys along the line of the side windows, contributing to effective impact absorption.

Impact sensors inside the cabin enable optimal timing for actuation of side curtain and front seat i-side airbag systems according to the type of side collision. Each vehicle is fitted with seven impact sensors, located at front center and either side of the front and rear seats. Vehicles such as minivans have 10 impact sensors including the additional sensors located in between and on either side of the third row of seats.*⁴

*4 The number of sensors may vary depending on the model.

Locations of Multipoint Sensors for Detecting a Variety of Collisions

(4) Driver-Side and Front Passenger-Side SRS Knee Airbag Systems

In frontal collisions, airbags that deploy under the steering wheel, on the driver side, and under the glove box, on the front passenger side, prevent forward movement of the seat occupant’s body and cushion the impact to the person’s lower limbs. Activating SRS knee airbag systems together with driver-side and front passenger-side i-SRS airbag systems helps to minimize the impact on the entire body, not just the lower limbs.

Knee Airbag Deployment (Driver-Side)

Honda set target values when developing the knee airbag systems, taking into account domestic and overseas safety standards, as well as the risk of injury to lower limbs of varying proportions, and abrasions. In addition to the shape and size of the airbags, a unique way of folding and storing the airbags (before deployment) was devised to ensure quick deployment immediately after actuation and uniform deployment in the space in front of both knees.

(5) Front Center Airbag System*⁵

This airbag is built into the backrest of the driver’s seat on the side of the seat in the middle of the cabin. Deploying in the space between the driver’s seat and the front passenger seat in the event of a side impact from the front passenger side, the airbag prevents the driver from hitting the passenger-side door and, if a front passenger is present, prevents the driver from colliding with the front passenger.

The front center airbag helps to protect the driver’s head. As well as being designed to wrap around the driver’s head, the airbag, together with the seatbelt pretensioner and center console, prevents any lateral displacement of the seat occupant.

*5 Adopted for European models from 2020

Evolution of Honda Airbag Systems

1987
SRS airbag system developed Japanese car first

Quick to pick up on the effectiveness of airbags, Japanese automakers commenced airbag research in the early 1970s. Seeking “the ultimate in reliability,” Honda spent 16 years developing a driver-side SRS airbag system, a first for a Japan-made vehicle. It was incorporated into the Legend.

1990
Top-mounted design developed (front passenger-side SRS airbag system) World first

The airbag deploys along the line of the windshield to avoid directly hitting the front passenger as it inflates. Many automakers still use the top-mounted design today.

1998
Dual-stage inflator developed (driver-side/front passenger-side i-SRS airbag systems) World first (for front passenger side)

Honda developed a dual-stage inflator that deploys airbags in two stages during low-speed collisions, but one quick step in high-speed collisions. This is to achieve the appropriate timing for contact between airbag and seat occupant in collisions of different speed.

1998
Front passenger posture detection function developed (i-side airbag systems) World first

A posture detection sensor installed in the front passenger seat detects the occupant’s build and posture to determine the person’s sitting height and head position and to control airbag deployment accordingly. A function developed to accompany this feature deactivates the airbag if, for example, the head of a child who has fallen asleep is inside the area where the airbag deploys. This is to avoid head impacts.

2002
Side Curtain Airbag System developed

Airbags covering the side windows almost completely deploy instantly in a side collision, effectively cushioning head impacts for not only front seat occupants, but also passengers in rear outboard seats and, in the case of minivans, third-row seats.

More information

2008
Airbag with continuously staged inflation developed (driver-side i-SRS airbag system) World first

The system features a spiral-shaped seam structure and a vent control valve to allow appropriate control of the airbag’s internal pressure and deployment by continuously increasing the volume of gas during inflation. Because the airbag deploys faster, with reduced impact, and can stay in an inflated state for a longer time, the system realizes elevated occupant protection performance, supporting a wide range of sitting positions and collision types, and airbag impact mitigation performance.

2014
Driver-/front passenger-side knee airbag systems developed

Airbags deploy from beneath the steering wheel and the glove box into the space in front of the occupants’ knees, preventing forward movement of front seat occupants’ bodies and cushioning the impact to the lower limbs.

More information

2016
Internal pressure-retaining type developed (front passenger-side i-SRS airbag system)

Pressure inside the inflated airbag is maintained until the seat occupant comes into contact with the airbag. This allows effective protection performance even when it takes longer for the seat occupant to come into contact with the airbag due, for example, to different types of build. A type has since been developed for the driver side, too.

More information

2020
Airbag system for brain damage mitigation in oblique collisions developed (front passenger-side i-SRS airbag system)

To mitigate brain damage that may be caused in an oblique frontal collision when the head of the front passenger lurches sideways due to the lateral force of the impact, Honda developed a new airbag capable of inflating in a way that prevents sideways movement of the head.

More information

2020
Front center airbag system developed (driver-side)

Deploying in the space between the driver’s seat and the front passenger seat in the event of a side impact from the front passenger side, this airbag prevents the driver from hitting the passenger-side door and, if a front passenger is present, prevents the driver from colliding with the front passenger.

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2020
Rear seat side airbag system developed

An airbag system to be built into the seat, effective for mitigating the impact of a side collision on a seat occupant’s chest, was developed for incorporation into both ends of the rear seat. They deploy quickly in the spaces between the rear seat occupants and the rear doors to cushion the impact.

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