WO2011039789A1

WO2011039789A1 - Passive safety device for a vehicle seat operating before the possible crash

Info

Publication number: WO2011039789A1
Application number: PCT/IT2010/000403
Authority: WO
Inventors: Andrea Cipriani
Original assignee: Andrea Cipriani
Priority date: 2009-09-29
Filing date: 2010-09-23
Publication date: 2011-04-07
Also published as: ITRM20090496A1; IT1396052B1

Abstract

The invention relates to a passive safety device for a vehicle seat operating before the possible crash, said seat provides a seat frame, coupled with the vehicle floor, and a back frame, as well as an intermediate frame, movably provided on said seat frame and on which it is pivoted for adjustment of said back frame, and a seatbelt, provided with a fixing point, a winder and a buckle for fixing said belt, said passive safety device providing an actuator, acting by coupling means with said fixing point, with said actuator and with said buckle of the seatbelt, following a "pre-crash" signal from a sensor, in order to realize a pre- tensioning of the seatbelt, said actuator further acting on said intermediate frame to make it advancing before a rear-ending, or moving backward before and/or during a front crash, thus causing displacement of the back frame.

Description

PASSIVE SAFETY DEVICE FOR A VEHICLE SEAT

OPERATING BEFORE THE POSSIBLE CRASH

The present invention relates to a passive safety device for a vehicle seat operating before the possible crash.

More specifically, the invention concerns a device of the above kind, realised to increase protection of passengers in case of front impact or in case of telescoping.

Solution suggested according to the present invention can be activated both before the crash, and only after the same crash occurred.

As it are well known, passive safety systems for vehicles aims reducing consequences for passengers.

Technology known as "pre-crash" comprises a series of sensors that can detect an imminent crash, informing an ECU, that will alert driver attention or activate actuators. Said actuators can help the driver to prevent impact or prepare to the impact various accessories present on vehicle, in order to reduce consequences on passengers.

Systems are presently provided on vehicles to protect passengers from front impacts, such as air-bag, pre-tensioning devices, load limiting devices, and seats provided with anti-sliding ramps.

Particularly, air-bag aims preventing that trunk and head of the driver get in touch with rigid parts of the passenger compartment, such as steering wheel steering column or dashboard.

Seatbelt pre-tensioning device eliminates slack of the same, to reduce impact of trunk on same seatbelt and sliding of seatbelt under the abdominal part in case of crash.

Ramp contributes to reduce risk of sliding under the seatbelt. Instead, load limiting device reduces force on trunk by yielding of one of the seatbelt component.

In any case, it is necessary bearing in mind that most of safety in a vehicle is due to capability of its structure to ensure structural integrity of passenger compartment. This is the reason why car manufacturers aim increasing passive safety, stiffening structures, and realising seatbelts and air bags always more efficient, able reducing passenger deceleration.

Recently devices have been added, such as ki ee protective air bags, abdominal part pre-tensioning device, or, as an alternative to the latter, sheet air bag of anti-sliding ramp, in order to reduce risk of impact of lower limbs against dashboard and steering wheel. In order to provide a full picture of the situation, most recent pre-crash devices realised by biggest car manufacturer will be described in the following.

Pre-crash device adopted by Mercedes Benz implements a technical solution patented by Faurecia, permitting positioning front seats so as to maximise seatbelts effect in case of crash. At the same time, said system permits tensioning seatbelts by electric actuators mounted on winding devices. Further, systems also intervene on secondary accessories such as sliding roof that is closed before the crash.

In this solution, it is provided, as far as seats are concerned, both a straightening of seat back, and an increase of cushion inclination, so that risk of passenger sliding under the seat belt is reduced, thus reducing risk of injuries of inside organs caused by belt abdominal part. Pre-tensioning of belts by motorised winding devices permits reducing slack of seatbelts. The above effect is added to the effect of pyrotechnical pre-tensioning devices always provided, and operating only when crash occurs.

However, said devices necessarily require an electronically adjustable seat.

In order to increase efficiency of the above device, it would be necessary providing a bigger air bag and seat belts provided with a progressive retaining system permitting ensuring a larger yielding. Main limit of this solution is space available between passenger and dashboard, or between driver and steering wheel.

Some solutions have been suggested, among which the solution described in US patent n° 6,193,296, assigned to Honda Motor, wherein it is suggested increasing the above space providing a quick movement of seats backward, said movement being caused by an actuator. The above device, never manufactured, would need an expensive and bulky actuator to move the whole seat backward, and does not provide solutions for a safe implementation of vehicles provided with rear seats.

Other known devices are those for protection against seatbelt, reducing consequences of the flick, such as device adopted by Volvo and known as WHIPS^®, patented by Autoliv. All vehicles adopting said device have seat back rotating with respect to the seat, thanks to an adjustment mechanism realised in such a way to deform in case of telescoping, due to the force exerted by the passenger, making the back inclining backward. Thus, acceleration to which passenger is subjected is reduced, and it is also reduced neck flexion. The above mentioned Volvo system provides mounting of seat back on the seat by a guide permitting a backward and rotation movement. Under standard conditions, seat back is maintained in its position by a stop element so sized to deform only if subjected to a set force.

However, the above device has the drawback to incline seat back reducing its capability of retaining passenger, since some manufacturers provide pre-tensioning of seatbelts even in case of telescoping, both for reducing risk of sliding from seatbelt, and both and for reducing bouncing after telescoping.

Drawback of said solution is that when seat back moves backward, injuries can be caused to lower limbs of passengers on rear seats.

It is also known a device for protection against seatbelt, known as "Active Head Restraint", comprised of a mechanism within the seat back, providing lifting and advancing headrest, thanks to the force exerted by passenger on the seat back in case of telescoping.

As to the use of pre-crash technology for protection against seatbelt, it can be mentioned a system realised and implemented by Toyota. It is a device comprised of millimetric wave radar, provided in the rear of the vehicle, an ECU, and a headrest, having a fixed portion mounted on seat back, and a movable portion. An actuator permits approaching movable portion to the passenger head. When radar detects an imminent telescoping, sends the information to ECU, the latter approaching movable portion of headrest to passenger head. Advancement movement is stopped by a contact sensor, when movable portion comes in contact with passenger head. Advantage of the above device is that of stopping head movement before crash, thus reducing flick risk.

However, use of this device on vehicles provided with other pre- crash devices requires mounting of two actuators on vehicle further to those provided for seatbelts pre-tensioning device.

In view of the above, it is suggested the solution according to the present invention, that, in case of front crash, can intervene both before the crash and when crash occurs, and aims to increase distance between driver and steering wheel, between front passenger and dashboard, and, if possible, between rear passenger and front seat.

Further object of the present invention is that of suggesting a device that, creating a larger space between driver and steering wheel, make it possible increasing air bag volume, and yielding of progressive retaining of seatbelts. Furthermore, by the solution according to the invention, legs are at a longer distance from passenger compartment rigid parts, and head is maintained at a longer distance from roof uprights, thus obtaining a better efficiency in reducing passengers deceleration, at the same time preventing or reducing force of contact against passenger compartment rigid parts, thus being it possible stiffening the vehicle structure, ensuring structural integrity of passenger compartment in case of violent front crash.

Further object of the present invention is that of providing a device permitting increasing protection in case of telescoping, thus reducing risk of causing injuries to legs or passengers seated on rear seats.

It is therefore specific object of the present invention a passive safety device for a vehicle seat operating before the possible crash, characterized in that said seat provides a seat frame, coupled with the vehicle floor, and a back frame, as well as an intermediate frame, movably provided on said seat frame and on which it is pivoted for adjustment of said back frame, and a seatbelt, provided with a fixing point, a winder and a buckle for fixing said belt on passenger, said passive safety device providing an actuator, acting by coupling means with said fixing point, with said actuator and with said buckle of the seatbelt, following a "pre-crash" alarm from a sensor, in order to realize a pre-tensioning of the seatbelt, said actuator further acting on said intermediate frame to make it advancing before a rear-ending, or moving backward before and/or during a front crash, thus causing displacement of the back.

Preferably, according to the invention, said actuator, in case of a front crash, is activated by a pyrotechnic charge, which is actuated by a front crash sensor.

Furthermore, according to the invention, said actuator is an electric actuator.

Always according to the invention, said actuator is connected with said seatbelt winder, fixing point and buckle by a Bowden cable. In a preferred embodiment of the passive safety device according to the invention, said actuator acts on an arm, which is connected with said means for connection with said seatbelt winder, fixing point and buckle, said arm being provided with means (particularly a spring) for automatic return in the rest position.

Particularly, said arm has a first stroke part only causing pre- tensioning of seatbelt, and a second stroke part that, my interference means with intermediate frame, causes displacement of the same, and consequent displacement of the back frame.

Furthermore, according to the invention, an anti-sliding bar is provided frontally with respect to said intermediate frame, that, when the device is activated, is approached to the passenger.

Always according to the invention said device is also provided with a head rest provided with safety system.

Present invention will be now described, for illustrative, but not limitative, purposes, according to its preferred embodiments, with particular reference to the figures of the enclosed drawings, wherein:

figure 1 shows a vehicle providing a first embodiment (PCS-X- L1) of the device according to the invention;

figure 2 shows different particulars of device according to the invention;

figure 3 schematically shows step of activation of device according to the invention in case of telescoping between two vehicles providing the above device according to a first mode;

figure 4 shows kinematic of front collision employing device according to the invention in a first mode;

figure 5 schematically shows activation steps of device according to the invention in case of telescoping between two vehicles providing the above device according to a second mode;

figure 6 shows kinematic of front collision employing device according to the invention in a second mode;

figure 7 shows different particulars of a second embodiment of the device according to the invention; and

figure 8 shows different particulars of a third embodiment of the device according to the invention.

Operation of a first embodiment of device according to the invention, generically indicated by reference PCS-X will be described in the following. PCS-X-L1 drawing (figure 1) shows a vehicle with driver, behind which a passenger is seated, both with a seatbelt. Vehicle is provided with a front pre-crash sensor 7 and with a rear pre-crash sensor 8, permitting detecting imminence of a crash, and with a sensor that can consider space available for retreat of seat back. Front seat of the vehicle is of the kind described in the above, and it is further provided driver air bag 11. Driver seat belt is provided with a standard winding device H, with an electric actuator controlled by pre-crash system ECU 10.

Main element of device is a seat for vehicle (see drawing PCS- X-AAM-L1 - figure 2). Seat has frame mounted on vehicle floor, by sliding guides, permitting adjusting its position with respect to longitudinal axis of vehicle. An intermediate frame is mounted on seat frame, on which seat back frame is mounted, along with its adjustment mechanism permitting varying its inclination with respect to the intermediate frame. Seat back frame also comprises headrest provided with Active Head Restraint. Intermediate frame integrates anti-sliding ramp and it can freely slide with respect to cushion frame, integrating anchoring of insertion between buckle and belt. Intermediate frame is fixed on seat frame during regular running of the vehicle, and if necessary it can be moved by an actuator controlled by an ECU 10 (see figure 11). ECU 10 can set direction of seat back movement and amount of said movement, based on data received from two pre-crash sensors, one of which is in a front position, and the other one in a rear position, besides a sensor permitting evaluating the available space for retreating the seat back. ECU 10 of pre-crash system is connected to air bag ECU 12, besides actuating air bag, actuate pyrotechnic charge causing seat retreat. ECU 12 receives signal from crash sensor 9. Actuator Y (figure 2) acts on a movable support V, on which metallic cables are anchored. A cable can be observed in the upper part of the support, having an anchoring acting as a pin sliding within a slot of the intermediate frame, acting as anchoring guide. Cable passes through a guide, having a cylindrical chamber within which piston slides, a cable being fixed to said piston, the piston being maintained in the proper position a spring. Beyond said chamber, cable crosses anti-sliding ramp guide, and is fixed to ramp sliding block. The above guides provided with a cable are mounted on two sides of intermediate frame, not to occupy seat space. Cable guides are fixed to the intermediate frame, so that movement of support can be in both directions. Spring is compressed and ramp approaches the driver. Observing right side of the seat, it is observed a similar mechanism or pre-tensioning buckle coupling and activation of Active Head Restraint. Front end of support has two anchoring points, on which ends of two Bowden cables are coupled, passing within a guide, and fixed to the same. Guide can slid within a seat integral with seat frame C, and it is maintained in the proper position by a return spring. Two Bowden cables are respectively connected to the belt lower fixing point and to winding device, and are provided with cylinder - piston, with a return spring.

When support retreats, put the belt under tension, approaching ramp and activating Active Head Restraint, lifting and advancing headrest. Seat back remains fixed, until when anchoring points which are provided at the centre of slots does reach rear ends of said slots. Once reached these ends, ramp, Active Head Restraint and coupling pre-tensioning device, are fully operated, while winding device and lower anchoring point pre-tensioning devices are only partially actuated. In case it is prosecuted support retreat, it also causes, beyond a further pre-tensioning of winding device and of lower anchoring point, also retreat of intermediate frame, and thus of seat back. Additional pre-tensioning of seatbelt caused by retreat of seat back, compensates loss of seatbelt tension, caused by seat back retreat.

When support advances, until the point where pin within slots are in touch with front ends of slots, as for retreat, ramp, Active Head Restraint and coupling pre-tensioning device are fully actuated. Two Bowden cables are anchored on a sliding cable guide, maintained in position by a spring, in order to prevent that when advancing the seat back, at the same time of seatbelt pre-tensioning, the same belt exerts a too large force on passenger. Movable support of anchoring points, besides being moved forward and backward by actuator, can be moved backward by a pyrotechnic charge Z, of the type usually employed for pyrotechnic pre-tensioning devices. The above pyrotechnic charge is connected by a metallic cable with an outer gear of ratio-gear 1. Another metallic cable connects inner gear of ratio-gear with movable support V. Ratio gear has a toothed wheel integral with a central gear, which, rotating, varies transmission ratio between inner and outer gear; said toothed wheel is coupled with electro-actuated toothed wheel 2, adjusting ratio gear. Electro actuated toothed wheel is controlled by ECU 10, on the basis of stroke available for retreat received from sensor 3. Thus, in case space is available when crash occurs, pyrotechnic charge will explode causing a set rotation of outer gear. Displacement of support V can be equal or lower than cable length returned inside by pyrotechnic charge, on the basis of transmission ratio set by ECU 10. Metallic cable connecting inner gear with movable support must be kept under tension even when movable support is moved by actuator Y, so that reduction gear must have a return spring similar to the spring provided in winding device. When pyrotechnic charge is activated, inner gear is integral with the outer one, said coupling being for example obtained by a centrifugal locking, activated by quick movement of outer gear. The above mechanism, permitting exploiting all the retreat strokes rather complex. As an alternative, it can be used a two or more stage pyrotechnic charge that can make different portion of cable coming back, thus not being any more necessary the electro-actuated gear 2. Reduction gear must be replaced by a mechanism without the intermediate gear for reduction. Thus two gears 14 will be provided, respectively an outer gear, that can rotate only by activation of pyrotechnic charge, and an inner gear, rotating according to both directions. With respect to the drawing, it rotates clockwise thanks to a spring, when support V retreats, so as to wind cable, maintaining the same under tension; rotating in an anticlockwise direction when support V advance, unwinding cable. When pyrotechnic charge explodes, cable connecting to outer gear make it rotating fast clockwise activating a centrifugal locking device making it integral with inner gear. Inner gear too rotates clockwise, winding cable and making support V retreating.

Reduction gear of previous embodiment (particular B) operates at the same way, with the additional provision of an intermediate gear varying transmission ratio between outer and inner gears, so as to obtain a simple variable stroke retreat pyrotechnic charge.

Activation sequence for a device mounted on two vehicles is shown in figure 3 (PCS-X-S1), so as to observe operation both in case of front crash and of rear crash, while in figure 4 (PCS-X-K1) it is shown kinematic of passenger for a front crash under mode 1. Mode 1 provides retreat of driver seat back only when crash occurs, not to interfere with driver driving capability.

Pre-crash sensors drive front and rear area of vehicle during step 1 (drawings PCS-X-S and PCS-X-K1). During step 2, front sensor detects an imminent front crash and at the same time it is detected space available for retreat of seat back, the above information being sent to ECU. ECU actuates first winding device actuator H in order to eliminate a possible too large slack, then movable support actuator, thus pre-tensioning seatbelt, making passenger ramp approaching, and activating Active Head Restraint, these devices being partially activated not to interfere with driver driving capability.

During step 3, a first step of crash occurs, during which pyrotechnic charge is activated, making air bag inflating and exploding pyrotechnic charge, terminating operation of devices started during step 2 and, in case space behind seat back permits it, causes retreat of intermediate frame.

During step 4, in order to reduce on passenger chest force exerted by seatbelt p rogressive retaining action, permits movement of advancement of passenger, coming in contact with air bag.

During step 5, passenger, after hitting against air bag, bounces against seat back.

In case of front crash, under mode 2, (figure 5 - PCS-X-K2), after actuation of winding device actuator, it is provided retreat of seat back since from step 2, the above retreat being completed during step 3by operation of pyrotechnic charge, if it has not been completed during step 2. This mode can be used without any contraindication for passenger seats, since they do not drive the vehicle, while it can be used only on driver seat when it cannot be avoided a violent impact.

Since pre-crash system are not infallible, pyrotechnic charge, in case of impact, in any case ensures full actuation of all devices. In case of telescoping, (figure 3 - PCS-X-S1 - and figure 6 - PCS-X-K3), during step 1 rear sensor monitor the following vehicle, during step 2 it is detected by ECU telescoping risk, pre-tensioning seatbelt, approaching anti-sliding ramp to passenger, activating Active Head Restraint and advancing seat back. Impact occurs during steps 3 and 4, and energy is absorbed by deformable connection between seat frame and intermediate frame. The above deformable connection is of the Autoliv type, mounted on Volvo cars, and similar devices have been also developed by other car manufacturers. Said device provides a retreat and rotation movement of the seat back. For telescoping, seatbelt pre-tensioning along with approaching of anti-sliding ramp, reduces risk of passenger slippering from seatbelt abdominal portion, due to seat back rotation, increasing retaining efficiency of seatbelt during bouncing step 5. By advancement of seat back, after pre-tensioning of seatbelt, driver can be better retained, thus exploiting at best seat back yielding. Advantage is that of reducing risks for rear passenger legs. Furthermore, in case it is decided to independently actuate Active Head Restraint, it would have an anticipated actuation.

Coming now to observe figures 7 - 8, two further embodiments of device according to the invention are shown.

Embodiment shown in figure 7 differs from the previous one by lower anchoring of seatbelt, integrated within seat (particular B); consequently, it is provided a cable guide with cylinder, piston and return spring, in lieu of Bowden cable. On right side of intermediate frame, slot X acting as anchoring guide, has been placed in correspondence of lower anchoring, and not as in PCS-X, this difference not involving a variation of the system operation, provided that two equal slots are provided on both sides of intermediate frame, and that sliding pins acting as anchoring elements are so positioned to act together on intermediate frame to make it advancing or retreating.

Embodiment of PCS-Z figure 8 is different with respect to PCS- Y figure 9 embodiment in that upper anchoring of seatbelt and winding device are integrated within seat back. This causes winding device pre- tensioning by a cable guide, a cylinder - piston and return spring, and a Bowden cable, from intermediate frame to winding device.

Provision of return springs on all devices ensures that all pre- tensioning devices, ramp and Active Head Restraint go back in the original position following the movement of the movable support when actuator brings it back in the original position. The above if crash has been avoided.

Also in these embodiments it is possible providing the multi- step pyrotechnic charge without ratio gear.

With respect to the Faurecia and Toyota devices, device according to the invention, uses, besides winding device actuator, also an actuator for pre-tensioning seatbelt on three points, bringing back seat in a safety condition, that does not permit straightening of seat back, reducing sliding risk, thanks to a simultaneous pre-tensioning action of abdominal portion and approaching of anti-sliding ramp. Slack elimination from abdominal portion occurs uniformly, since both ends of abdominal portion are pulled, so ensuring a proper position of passenger pelvis while sinks in seat back. The above is true both when electric actuator is activated, and when the situation is more risky, when pyrotechnic charge is activated, and a pelvis rotation, caused by pre-tensioning only on one side of abdominal portion that can cause injuries to lumbar vertebrae. Winding device actuator, used in standard pre-crash systems, aims bringing safety bolt at such a tension to ensure optimum operation of pyrotechnic pre- tensioning device. In fact, actuator still winds seatbelt until a set resistance is detected. In PCS, seat actuator cannot eliminate an excessive slack due to lack of attention by the passenger when fastening the seatbelt, object of said actuator being that of contributing to recovering a set slack, making it before pyrotechnic charge, the latter, aiming retreating seat back would require too much time for full pre-tensioning of seatbelt and seat back retreat. This is the reason why winding device actuator is provided in PCS, usually employed in pre-crash devices for recovering excessive slack. After the winding device pre-tensioning actuation, additional pre-tensioning device of seat electric actuator does not interfere with capability of driver of preventing crash, since slack is recove red on three points, without restraining too much the driver. Anticipated actuation of Active Head Restraint and of ramp ease work of pyrotechnic charge, making to the latter a smaller and thus less dangerous movement, thus reducing risk of violent contact of headrest and of ramp with driver.

Present invention has been described for illustrative, but not limitative purposes, according to its preferred embodiments, but it is to be understood that variations and/or modifications can be introduced by those skilled in the art without departing from the scope as defined in the enclosed claims.

Claims

1. Passive safety device for a vehicle seat operating before the possible crash, characterized in that said seat provides a seat frame, coupled with the vehicle floor, and a back frame, as well as an intermediate frame, movably provided on said seat frame and on which it is pivoted for adjustment of said back frame, and a seatbelt, provided with a fixing point, a winder and a buckle for fixing said belt on passenger, said passive safety device providing an actuator, acting by coupling means with said fixing point, with said actuator and with said buckle of the seatbelt, following a "pre-crash" alarm from a sensor, in order to realize a pre- tensioning of the seatbelt, said actuator further acting on said intermediate frame to make it advancing before a rear-ending, or moving backward before and/or during a front crash, thus causing displacement of the back.

2. Passive safety device according to claim 1 , characterized in that said actuator, in case of a front crash, is activated by a pyrotechnic charge, which is actuated by a front crash sensor.

3. Passive safety device according to one of the preceding claims, characterized in that said actuator is an electric actuator.

4. Passive safety device according to one of the preceding claims, characterized in that said actuator is connected with said seatbelt winder, fixing point and buckle by a Bowden cable.

5. Passive safety device according to one of the preceding claims, characterized in that said actuator acts on an arm, which is connected with said means for connection with said seatbelt winder, fixing point and buckle, said arm being provided with means (particularly a spring) for automatic return in the rest position.

6. Passive safety device according to one of the preceding claims, characterized in that said arm has a first stroke part only causing pre-tensioning of seatbelt, and a second stroke part that, my interference means with intermediate frame, causes displacement of the same, and consequent displacement of the back frame.

7. Passive safety device according to one of the preceding claims, characterized in that an anti-sliding bar is provided frontally with respect to said intermediate frame, that, when the device is activated, is approached to the passenger.

8. Passive safety device according to one of the preceding claims, characterized in that said device is also provided with a head rest provided with safety system.