Patent Application
20100286873
Pre-impact braking systems are being introduced in automotive vehicles as a means for improving the vehicle safety. Upon detection of an imminent collision by the vehicle collision warning system, using a combination of RADAR, vision and LIDAR sensors, the vehicle activates the brakes just prior to impact. In some cases, this braking can avoid an accident altogether, and in cases where the vehicle speed is too great to avoid the accident, the application of the brakes prior to impact reduces the kinetic energy of the vehicle and thereby the severity of impact. One design concern of these pre-impact braking systems is that the braking may cause the occupants to move forward relative to the vehicle interior just prior to impact. This could potentially put them in the airbag deployment zone, should the airbag deploy as a result of the impact.
One method of addressing this concern is the addition of motorized belt pretensioners (MBPs) to the restraints systems. These motorized belt pretensioners use an electric motor to quickly wind the seat belt retractor just prior to impact. The slack is removed from the seat belt system so it can better restrict the forward movement of the occupant. Although the motors are not strong enough to prevent forward movement altogether, they can significantly reduce the forward motion of the occupant to the point where the occupant is prevented from moving into the airbag deployment zone. The MBPs also have the ability to be electronically activated by a signal from the Restraints Control Module (RCM), and can be deactivated after the impact is complete, or if there was a near miss that the sensing system initially detected as an imminent collision, but driver interaction or other factors caused the collision to be avoided.
Although the systems described above provide additional protection to the vehicle occupants, there are a number of practical shortcomings. One, the MBPs are relatively large and may be difficult to package in the vehicle. The package constraints limit the size of the motor that can be used, which results in pretensioning levels significantly lower than typical pyrotechnic pretensioners. Thus, the MBPs may not be fully capable of preventing forward movement of the occupant, but may only reduce the occupant's forward movement. The MBPs also use a significant amount of power to pretension and hold the seatbelts, which requires modifications to the vehicle electrical system.
A potential alternative to MBPs for controlling the payout of the belts during braking is web grabbers. These web grabbers actually tighten onto the seatbelt webbing and prevent it from spooling off of the seat belt retractor. They are strong enough to hold an occupant and keep them from moving forward during pre-impact braking. However, these devices are currently mechanically activated by the forces of a collision, and lack the control required to activate them prior to collision and/or deactivate them after a potential collision is avoided.
There is a need for an electrically activated web grabber in conjunction with the pre-impact braking system to reduce forward occupant movement.
There is further a need for an electrically activated, electronically controlled web grabber in conjunction with a pre-impact braking system that holds the vehicle safety belt from the moment of activation, preventing forward movement of the occupant. The web grabber can be activated prior to the impact to ensure occupant containment and deactivated upon command in order to release after an accident is avoided, or once the impact has started to allow other safety devices, for example load limiters, to take over control of the belts.
In one aspect, one embodiment of the present application relates to a method to operate a vehicle occupant restraint safety system in association with a vehicle seat. One such method may include the steps of:
determining, by means of a collision warning system, whether a vehicle collision event is imminent;
activating pre-impact braking;
activating a seat belt web grabber;
determining whether an actual vehicle collision event has occurred;
activating a vehicle occupant restraint safety system; and
deactivating said seat belt web grabber.
The seat belt web grabbers may be electronically controlled by an electronic control module, such as, a restraint control module. Moreover, the activation of a pre-impact braking system may be determinative of an imminent vehicle collision event.
Turning now to the drawings wherein like numbers refer to like structures, and particularly to
The electrically activated web grabber works in conjunction with the collision warning system and the pre-impact braking system to reduce occupant forward movement. The web grabber holds the belt from the moment of activation, preventing seat belt webbing from leaving the retractor, and thus restricting the forward movement of the occupant. It can be activated prior to or simultaneously with pre-impact braking to ensure occupant containment and can be deactivated upon command in order to release after an accident is avoided, or once the impact has started to allow other safety devices, such as, load limiters to take over control of the belts.
These electronically activated web grabbers are controlled by the restraints control module according to the state diagram shown in
In order to facilitate release of the web grabbers, the clamping mechanism must be spring loaded, or actively opened with a solenoid. The clamping surface must also be designed to facilitate release of the clamping force while under load from the occupant's forward movement. Even with these design requirements, the electrically activated web grabbers are smaller and less complex than motorized belt pretensioners. The solenoid activated web grabbers also can be activated significantly faster than larger, motorized belt pretensioners, due to inertial effects.
In this regard, reference is made to
An alternate embodiment included within this application is to use electronically-activated retractor locks to restrict occupant movement during braking. As seen in
In the embodiment of
Some vehicles are equipped with inertially activated retractor locks which require a significant G-force at the retractor (approx. 0.4 G) to activate. This means that the retractors do not lock until some time after high-level braking is initiated or possibly not until after the crash pulse begins. When a retractor incorporates electronically-activated locks, the retractor could be locked at the moment of autonomous braking, resulting in significantly lower belt payout than the inertially activated retractor lock. The electronic retractor locks would be adequate at reducing pre-impact braking induced occupant displacement to the point where the occupant does not enter the airbag deployment zone, although they allow more belt payout than web grabbers. In any embodiment of this disclosure, the electronically controlled vehicle seat safety restraint system results in a pre-impact restraint system which improves upon the motorized belt pretensioners in cost and timing when used with pre-impact braking systems.
The words used in this application are words of description, not words of limitation. Various modifications will be apparent to one skilled in the art without departing from the scope and spirit of the invention as set forth in the appended claims.
