I have three US patents for different embodiments of an auto safety bumper invention.
Cars must become smaller and lighter to meet government CAFE rules. Today, small cars are less safe in collisions than larger cars. The small cars don't have large crumple zones. In fact, many small cars don't have extended trunks that provide a large crumple zone for larger cars.
I propose to add a box full of polyurethane foam which gets crushed in a collision. The foam has a stress strain curve like that of steel. The force on it becomes flat and that reduces the g forces on the passengers as long as foam is being crushed.
Fig 1 show a box that is shared by side and rear bumpers. Sharing of the poly foam allows for more foam to be available for a side or rear collision.
Fig 2 shows how the amount of foam crushed can be selected by a sensor that measures the intensity of the collision. A large amount of foam may not be crushed at all in a lower speed collision, and the foam will not reduce the g forces at all. By selecting the best amount of foam per collision, the maximum g forces on the passengers is minimized.
Fig 3 shows a box of foam with a single bumper.
The box can be quickly attached or removed from the vehicle.
This design can be an aftermarket product.