WO2008125954A2

WO2008125954A2 - Frontal restraint system with seat belt for a seat of a vehicle

Info

Publication number: WO2008125954A2
Application number: PCT/IB2008/000887
Authority: WO
Inventors: Veniero Pizzagalli
Original assignee: Ferrari S.P.A.
Priority date: 2007-04-12
Filing date: 2008-04-11
Publication date: 2008-10-23
Also published as: WO2008125954A3; ITBO20070268A1

Abstract

Frontal restraint system (1) with seat belt (3) for a seat (2) of a vehicle; the frontal restraint system (1) is provided with: a seat belt (3); a first lower anchorage of the seat belt (3); a second lower anchorage of the seat belt (3) arranged on an opposite side of the seat (2) with respect to the first lower anchorage; and at least one actuator device (12), which in the event of frontal impact moves at least the first lower anchorage of the seat belt (3) downwards.

Description

FRONTAL RESTRAINT SYSTEM WITH SEAT BELT FOR A SEAT OF A VEHICLE

TECHNICAL FIELD

The present invention relates to a frontal restraint system with seat belt for a seat of a vehicle.

The present invention is advantageously applied to a car, to which the following description will explicitly refer without any loss of its generality.

PRIOR ART

All car manufacturers submit their products to a series of destructive tests in order to certify that the car meets the relevant requirements of safety standards and regulations in terms of occupant protection. For this reason, all cars are equipped with frontal restraint systems and possibly also lateral systems that enable compliance with the safety standards and regulations in force in the countries in which they will market the car.

The frontal restraint system almost always envisages the use of a seat belt and a frontal airbag. In the event of frontal impact (against another vehicle or against any other static or dynamic object) the presence of the seat belt and frontal airbag enables the occupant to be restrained in the seat. Otherwise, the deceleration resulting from the impact would cause the occupant of the seat to impact against the internal surfaces of the vehicle and receive injuries of a more or less serious nature depending on the severity of the impact. In particular, seat belts, placed on the market for the first time in 1960, have become mandatory by law in all Western countries and are an essential requirement in order for cars to be certified and approved In almost all of the cars currently on the market, three-point seat belts are used; only some high- performance cars (such as, for example, those manufactured by Ferrari or Lamborghini) feature four- point seat belts as optional equipment, while five and six-point seat belts are only used in Formula 1, Nascar, or rally-type competition vehicles.

The main elements of a three-point seat belt are a retractor, a guide ring that is fixed in a raised position, for example, to an upright of the frame of the car, a stalk, a buckle that is suitable to be locked to the stalk, an anchor plate that is arranged on the side of the seat opposite the stalk, and a seat belt that is partially rolled up in the retractor and passes through the guide ring, the buckle and the anchor plate. In the case of an adjustable seat (almost all car seats) , the stalk is always mounted on the seat so that it moves with said seat while the anchor plate can be mounted on the seat or be directly attached to the frame of the car in a fixed position.

The terminal part of the stalk and the anchor plate constitute the lower anchorages of the seat belt. The load is transferred from the seat belt (that is, from the occupant) to the frame of the car (directly and via the seat structure) through the lower anchorages. Furthermore, the position of the lower anchorages with respect to the occupant determines the position of the lap belt portion of the seat belt with respect to the occupant ' s pelvis .

The lower anchorages of the seat belt must be positioned so as to meet the requirements of European and American regulations, which define the areas of feasibility within which both lower anchorages must be located. The purpose of these requirements is to ensure that the position of the lower anchorages is suitable in order to effectively restrain the occupants in their seats. The final position of the lower anchorages should achieve the best compromise between comfort, that would have the lap belt portion of the seat belt retracted and higher than the occupant's pelvis, and good restraint capability that, on the contrary, would require a lap belt portion of the seat belt to be in a forward position with the lower portion of the seat belt sitting on the upper front part of the pelvis, that is, in correspondence with the iliac crests. In the event of frontal impact, which due to inertial force causes the occupant to move forward in the passenger compartment of the car, the seat belt, sitting on the occupant's pelvis, is able to ensure the necessary restraint, keeping the occupant's body from impacting against the internal surfaces of the passenger compartment and therefore preventing dangerous injury. The pelvis is the strongest bone in the human body and- it has been shown that its strength deteriorates only slightly with age; thanks to these characteristics, by making sure the lap belt portion of the seat belt sits on the pelvis it is possible to ensure adequate restraint regardless of the age of the occupant of the vehicle . It should be noted that, in general, the aforesaid compromise must be satisfied as far as possible without unbalancing the position of the lower anchorages, for example, to produce a condition that ensures good restraint and little comfort, or vice versa. If too much preference is given to comfort, occupant restraint will be less and in the event of impact the occupant will violently impact against the internal surfaces of the passenger compartment; on the other hand, if too much preference is given to occupant restraint to the detriment of the level of comfort that is perceived, driving safety is also potentially penalized as the occupant will be continually distracted by the seat belt as it causes discomfort while driving (it has been scientifically demonstrated that driving stress adversely affects the likelihood of an accident) .

The seat belt is able to provide the necessary occupant restraint when it sits properly on the pelvis; the fact that the seat belt sits properly on the pelvis is closely linked to the position of the lap belt portion of the seat belt with respect .to the iliac crests of the pelvis. Due to the forward motion by the occupant due to the effect of a frontal impact, the angular position of the lap belt portion of the seat belt may vary with respect to the occupant's pelvis, with a consequent risk that the seat belt may slip from the iliac crests of the pelvis. When the lap belt portion of the seat belt slips off the iliac crests of the occupant's pelvis due to the forward motion of the latter, this is called submarining; in the event of submarining, the occupant is held less securely and, above all, the load transmitted by the lap belt portion of the seat belt is no longer supported by the occupant's pelvis but is shifted onto the occupant's abdomen, which can cause potentially serious injury to the occupant's internal organs.

It is important to note that the likelihood of submarining is far from negligible: studies conducted in the United States and some European countries have confirmed that if, on the one hand, the use of seat belts has helped to reduce the incidence of very serious injury to the head and thorax (AIS ≥ 4), on the other hand, it has caused a sharp increase in the incidence of abdominal injury; studies have shown that, for adults involved in a frontal crash at high speed, 20% of AIS ≥ 5 relate to abdominal trauma as a result of injury of the internal organs caused by seat belts . The percentage is reduced to 17% for AIS≥ 4 and AIS≥ 3 injuries.

However, the likelihood of abdominal injury associated with the use of seat belts is considerably higher in the case of children: studies conducted in the United States have shown that the abdomen is the second most damaged part of the body in children using seat belts. The younger the child, the greater the likelihood of injury due to the smaller size of the pelvis. The average age of children who suffer abdominal injury arising from the use of seat belts is 7.3 ± 2.5 years and the children at the greatest risk of abdominal injury are those between 4 and 8 years of age. To summarize, the root cause of serious abdominal injury among seat belt-wearers is submarining, that is, the effect that causes the seat belt to slip onto the abdomen and therefore transfer the load directly onto the abdomen, with consequent laceration of the internal organs due to the marked penetration of the seat belt.

Various solutions have been proposed to counteract submarining; for example, one such proposal consists of counteracting the tendency for the seat occupant's pelvis to slide forward in the event of frontal impact by incorporating an anti-slip or anti-submarining bar into the car seat. Said bar is sunk into the front part of the seat area and is arranged transversely to the direction of motion. An example of a seat provided with an anti-slip or anti-submarining element is provided by patent application US2002190548A1. A further example of a seat provided with an anti-slip or anti-submarining element is provided by patent application US2006125296A1 which describes a seat for a car including an anti- submarining element, which is sunk into the seat, is arranged transversely to the direction of motion of the car and is movable under the action of an actuator between a home or deactivated position and a working or active position; in the event of an accident, the actuator moves the anti-submarining element automatically and quickly into the working position.

To counteract submarining, patent application EP1394002 and patent application JP2005193846 propose lowering the stalk and/or the anchor plate (namely the lower anchorages of the seat belt) in the event of frontal impact .

However, the constructive solution proposed in patent application JP2005193846 has several disadvantages since lowering the stalk involves turning the stalk downwards with its consequent forward displacement; said forward displacement of said stalk cancels the restraint of the occupant, resulting in a further forward movement thereof that can be very dangerous as it could cause the occupant to impact against fixed parts of the passenger compartment (particularly in economy or sports cars in which there is limited internal space) .

The constructive solution proposed by patent application EP1394002 also has various disadvantages, as it requires the use of a hinged ramp to rotate downwards in the event of an accident; this ramp is particularly cumbersome especially in view of the fact that to be able to rotate downwards, it requires free space below. Consequently, this constructive solution is hardly used in economy or sports cars where there is limited internal space; furthermore, this constructive solution imposes numerous dimensional constraints that negatively impact the aesthetic appearance of the seats.

DESCRIPTION OF THE INVENTION

The purpose of the present invention is to provide a frontal restraint system with seat belt for a seat of a vehicle, said frontal restraint system overcoming the disadvantages described above and, at the same time, being simple and cost-effective to produce.

According to the present invention, a frontal restraint system with seat belt for a vehicle seat is produced as set forth in the appended claims .

BRIEF DESCRIPTION OF THE DRAWINGS T- ^'

The present invention will now be described with reference to the attached drawings, illustrating a non- limiting embodiment thereof, in which:

• Figure 1 is a schematic perspective view of a frontal restraint system with seat belt produced in accordance with the present invention;

• Figure 2 is a schematic elevated side view of an occupant seated on a seat provided with the frontal restraint system of Figure 1;

• Figure 3 is a schematic view of a lap belt portion of a seat belt of the frontal restraint system of Figure 1 arranged over the pelvis of an occupant;

• Figure 4 is a schematic perspective view of an actuator device of the frontal restraint system of Figure 1;

• Figure 5 is a schematic perspective view of a variant of the actuator device of Figure 4; and

• Figure 6 is a schematic perspective view of an additional variant of the actuator device of

Figure 4. PREFERRED EMBODIMENTS OF THE INVENTION ■ In Figure 1, number. 1 indicates/, as ^'a whole, a frontal ^"restraint system with seat belt for. a seat "2 (illustrated in Figure 2) of a car. The frontal restraint system 1 comprises a seat belt 3, a retractor 4, in which the seat belt 3 is partially rolled-up, a guide ring 5, which is fixed in a raised position, for example, to an upright of the frame of the car, through which, the seat belt 3 passes and which constitutes an upper anchorage of said seat belt 3, a buckle 6 mounted slidingly on the seat belt 3, a stalk 7, which constitutes a lower anchorage of the seat belt 3 and is suitable to receive and block the buckle 6, and an anchor plate 8, which is arranged on an opposite side of the seat 2 from the stalk 7, constitutes a further lower anchorage of the seat belt 3 and supports said seat belt 3. If the seat 2 is adjustable, the stalk 7 is always mounted on the seat 2 so as to move together with said seat 2 while the anchor plate 8 can be mounted on the seat 2 or fitted directly to the frame of the car in a fixed position.

According to that illustrated in Figures 1 and 2, the seat belt 3 has a lap belt portion 9, which extends between the two lower anchorages (that is, between the stalk 7 and the anchor plate 8) and rests on the occupant's pelvis, and a chest belt portion 10, which extends between a lower anchorage and the upper anchorage (that is, between the stalk 7 and the guide ring 5) and rests ^• against the_. chest and - one shoulder of the occupant. ^{• •} ■ -

According to that illustrated in Figure 1, the frontal restraint system 1 comprises two identical (i.e. twin) actuator devices 11 , which are^' coupled to their respective lower anchorages of the seat belt 3 to move said lower anchorages downwards in the event of frontal impact. According to a different embodiment that is not illustrated, a single actuator device 11 is provided coupled to a single lower anchorage of the seat belt 3.

According to that illustrated in Figure 4, each actuator device 11 comprises a rectilinear guide 12, essentially vertical, that is fixed by means of screws to the frame of the seat 2 or to the frame of the car and a slide 13, which is slidingly coupled to the rectilinear guide 12 and supports the lower anchorage of the seat belt 3. Preferably, the lower anchorage of the seat belt 3 is hinged to the slide 13 in order to be able to freely rotate in relation to said slide 13.

In addition, each actuator device 11 comprises a pyrotechnic linear drive 14, which comprises a tubular casing 15, a piston 16 mounted slidingly inside the tubular casing 15, and a pyrotechnic charge 17 that, when detonated due to the effect of an electrically activated trigger 18, moves the piston 16 with respect to the tubular casing 15. Finally, each actuator device 11 comprises a mechanical gear 19, which transmits the motion from the piston 16 of the pyrotechnic drive 14 to the slide 13 to move said slide 13 downwards .

According to the embodiment illustrated in the attached figures, the mechanical gear 19 is of the rack type and comprises a rack 20 integral with the piston 16 (preferably the piston 16 and the rack 20 are part of a same single piece) , a rack 21 integral with the slide 13 (preferably the slide 13 and the rack 21 are part of a same single piece) , and a toothed wheel 22 that engages both the rack 20 of the piston 16, and the rack 21 of the slide 13.

When the mechanical gear 19 comprises a single toothed wheel 22, then the piston 16 and the slide 13 must necessarily move in opposite directions; consequently, the actuator device 11 has a relatively large overall size. As illustrated in Figure 5, to reduce the overall dimensions of the actuator device 11 (by about 20%) the mechanical gear 19 may be provided with two toothed wheels 22 so that the piston 16 and the slide 13 move in the same direction; in this case a first toothed wheel 22 engages the rack 20 of the piston 16 and a second toothed wheel 22 engages the first toothed wheel 22 and also with the rack 21 of the slide 13. The two toothed wheels 22 may have the same diameter (as illustrated in Figure 5) to determine a unitary gear ratio or different diameters to determine non-unitary gear ratios to increase or reduce the movement generated by the pyrotechnic drive 14. According to additional embodiments that are not illustrated, the .. mechanical gear 19 could comprise more than two toothed wheels 22 (for example, three or four toothed wheels 22) .

According to the embodiment illustrated in Figure 6, each actuator device 11 comprises only the pyrotechnic linear drive 14, which in turn comprises the tubular casing 15, the piston 16 mounted slidingly inside the tubular casing 15, and the pyrotechnic charge 17 that detonates due to the effect of an electrically activated trigger 18, moving the piston 16 with respect to the tubular casing 15. In this case, the mechanical gear 19 that connects the lower anchorage of the seat belt 3 to the piston 16 of the pyrotechnic linear drive 14 consists only of a rigid linkage that makes the lower anchorage of the seat belt 3 integral with the piston 16 of the pyrotechnic linear drive 14. According to a preferred embodiment, the actuator device 11 comprises a C-shaped support 23, inside which the tubular casing 15 of the pyrotechnic linear drive 14 is supported; in this case, an upper plate 24 of the support 23 has a through hole 25 through which the piston 16 of the pyrotechnic linear drive 14 passes. The path of descent of the lower anchorages of the seat belt 3 is normally vertical so that said lower anchorages can only shift downwards. Alternatively, the - path of descent of the lower anchorages of the seat belt 3 could slope forward (that is, in the direction of movement of the vehicle, or towards the front part of the seat 2) to compensate for the increased tension on the seat belt 3 resulting from the lowering of said lower anchorages . In other words , when the lower anchorages of the seat belt 3 move downwards this also increases the tension on the seat belt 3 i.e. causing a pre-tensioning of the seat belt 3; this pre-tensioning of the seat belt 3 could be excessive and could thus induce too much force on the occupant. Thus, to reduce such pre-tensioning it may be necessary to tilt each rectilinear guide 12 forward to make the lower anchorages of the seat belt 3 move both downwards and forwards .

According to the embodiment illustrated in the attached figures, the frontal restraint system 1 uses a seat belt 3 with three anchor points; according to a different embodiment that is not illustrated, the frontal restrain system 1 could use a seat belt 3 with four or more anchor points (typically four anchor points : two lower anchorages and two upper anchorages ) .

According to that illustrated in Figure 3, a belt angle β is defined as the angle between the straight line a and the straight line b defined as follows: the straight line a links the lower anchorage of the seat belt 3 projected on the longitudinal vertical mid plane of the pelvis (point A) with the midpoint of the seat belt 3 on the same plane (point B); .the straight line b links the projection of the centre of the joint between the trunk and the thigh (point C) on the longitudinal vertical mid plane of the pelvis with point D given by the projection on the same plane of the front and upper points of the iliac crests of the pelvis.

The belt angle β defined above represents the parameter that controls the submarining phenomenon: in order to prevent submarining, the belt angle β must stay within a certain range during the forward motion of the occupant with respect to the vehicle following frontal impact .

The lowering of the lower anchorages of the seat belt 3 in the event of frontal impact enables the belt angle β to remain fairly constant, therefore preventing submarining, that is, preventing the lap belt portion 9 of the seat belt 3 from slipping from the iliac crests of the occupant ' s pelvis . The frontal impact system 1 described above has many advantages, as it is simple and cost-effective to produce (it can therefore also be mounted in low-end economy cars) and enables the lowering of the lower anchorages of the seat belt 3 in the event of frontal impact in order to prevent submarining, and thus prevent abdominal injury to the occupants of the vehicle. In particular, the actuator device 11 is simple and cost- effective to produce/ is particularly sturdy and ^• above all it is extremely compact and can therefore also be easily mounted on economy or sports cars in which there is limited internal space. It is important to note that high performance sports cars generally have a very aggressive design with the car roof at the minimum possible height from the ground. In these conditions, optimizing the head trajectory of an unbelted car-seat occupant during a frontal impact (according to the load requirements of American standard FMVSS 208) is a critical aspect. During the unbelted frontal crash test the head must not impact against the internal surfaces such as, for example, the finishing of the windshield crossbar; this type of impact is one of the most dangerous as it generally causes significant neck compression associated with a stretching movement that causes severe trauma and in the most critical cases can be fatal for the occupant . The rigidity and shape of the seat would have to be altered to control the head trajectory during an unbelted frontal crash: it is 'clear that with a seat geometry devoid of significant discontinuity and seat rigidity reduced to a minimum the level of the head trajectory is reduced to a minimum height in an unbelted frontal crash, since the occupant "penetrates" the seat which, by its very nature, is soft. However, a less rigid seat with geometry lacking discontinuity tends to favor the emergence of the submarining effect in the event of a belted frontal impact; it is therefore clear that it is necessary to achieve a compromise between the two opposite needs of safeguarding the head trajectory during an unbelted frontal impact (less rigid seat with bottom devoid of significant geometrical discontinuities) and of preventing submarining in the event of a belted frontal impact (very rigid seat, geometrically formed in order to retain the occupant) .

Lowering the lower anchorages of the seat belt 3 in the event of frontal impact, enables submarining to be eliminated regardless of the shape of the seat so that the seat can be optimized with regard only to the need to safeguard the head trajectory during an unbelted frontal impact; this reduces the constraints on the shape of the interior of the car and therefore makes it possible to create a car with a more aggressive design

(that is, with a reduced height of the vertical cross section of the vehicle) .

Given the many advantages provided by the frontal restraint system 1 described above, such frontal restraint system 1 may be effectively used in any type of road vehicle (vans, trucks, buses, etc.) or non-road vehicle (trains, ships, aircraft, etc.).

Claims

C L A I M S

1) Frontal restraint system (1) with seat belt (3) for a seat (2) of a vehicle; the frontal restraint system (1) comprises: a seat belt (3) ; a first lower anchorage of the seat belt (3); a second lower anchorage of the seat belt (3) arranged on an opposite side of the seat (2) with respect to the first lower anchorage; and at least a first actuator device (11) , which in the event of frontal impact moves at least the ^■ first lower anchorage of the seat belt (3) downwards; the frontal restraint system (1) is characterized by the fact that the first actuator device (11) comprises : a pyrotechnic linear drive (14) , which comprises a tubular casing (15), a piston (16) mounted slidingly inside the tubular casing (15) , and a pyrotechnic charge (17) that when detonated moves the piston (16) with respect to the tubular casing (15) ; and a mechanical gear (19), which transmits the motion from the piston (16) of the pyrotechnic drive (14) to the first lower anchorage of the seat belt (3) to move said first lower anchorage downwards.

2) Frontal restraint system (1) according to claim 1, wherein the first actuator device (11) comprises: an essentially vertical rectilinear guide (12); a slide (13), which is coupled slidingly to the rectilinear guide (12), supports the first lower anchorage of the seat belt (3) and is moved downwards by the action of the mechanical gear (19) .

3) Frontal restraint system (1) according to claim 2, wherein the first lower anchorage of the seat belt (3) is hinged to the slide (13) in order to be able to freely rotate in relation to said slide (13) . 4) Frontal restraint system (1) according to claim 2 or 3 , wherein the mechanical gear (19) is of the rack type and comprises : a first rack (20) integral with the piston (16) ; a second rack (21) integral with the slide (13); and at least one toothed wheel (22) that engages both the first rack (20) and the second rack (21) .

5) Frontal restraint system (1) according to claim 4, wherein the mechanical gear (19) comprises: a first toothed wheel (22) that engages the first rack (20); and a second toothed wheel (22) that engages both the first toothed wheel (22) and with the second rack (21) .

6) Frontal restraint system (1) according to claim 1, wherein the mechanical gear (19) that connects the lower anchorage of the seat belt (3) to the piston (16) of the pyrotechnic linear drive (14) consists only of a rigid linkage that makes the lower anchorage of the seat ^•belt (3) integral with .the piston (16) of the pyrotechnic linear drive^' (14).

7) Frontal restraint system (1) according to claim 6, wherein the actuator device (11) comprises a C-shaped support (23), inside which the tubular casing (15) of the pyrotechnic linear drive (14) is supported.

8) Frontal restraint system (1) according to claim 7, wherein an upper plate (24) of the support (23) has a through hole (25) through which the piston (16) of the pyrotechnic linear drive (14) passes.

9) Frontal restraint system (1) according to one of the claims from 1 to 8, wherein the path of descent of the first lower anchorage of the seat belt (3) slopes forward to compensate for the increased tension on the seat belt (3) resulting from the lowering of said first lower anchorage.

10) Frontal restraint system (1) according to one of the claims from 1 to 9 and comprising a second actuator device (11), which is identical to the first actuator device (11) and in the event of frontal impact moves the second lower anchorage of the seat belt (2) downwards .

11) Frontal restraint system (1) according to one of the claims from 1 to 10 and comprising at least one upper anchorage of the seat belt (3) .

12) Frontal restraint system (1) according to claim 11 and comprising: a retractor (4), wherein the seat belt (3) is partially rolled-up; a buckle (6) mounted slidingly on the seat belt (3); a guide ring (5), which constitutes the upper anchorage, slidingly houses said seat belt (3) and is fixed in a raised position; a stalk (7), which constitutes the first lower anchorage of the seat belt (3) and is suitable to receive and block the buckle (6) ; an anchor plate (8), which constitutes the second lower anchorage of the seat belt (3) and supports said seat belt (3) .