Child seat arrangement on a motor vehicle seat

[0002] The invention relates to an arrangement of a child seat on a vehicle seat and a method of fastening a child seat on a vehicle seat.

[0003] Up to now, child seats in vehicles have usually been fastened by means of the vehicle-side belt system or by means of additional belts mounted in the vehicle. In the future, there will be the so-called ISOFIX Standard which is established or will be established in various standards. The ISOFIX Standard requires a basically rigid connection to adapters on the vehicle seat by means of locking elements on the child seat. As a result of this direct connection, the child seat is decelerated with the vehicle without any time shift. The connection of a child seat to a vehicle seat according to the ISOFIX Standard is described, for example, in German Patent Document DE 299 03 414 U1.

[0004] However, it is a disadvantage of a connection according to the ISOFIX Standard that, in the event of a crash, the child will still experience a certain forward displacement in the driving direction as a result of the child seat's own belt system, while the child seat itself remains rigidly connected with the vehicle seat. This reduces the child's wedging in the vehicle seat. Particularly in the event of a rebound, there is the danger, in the case of a child seat with a lap belt and a catch tray, that the child may be “pulled out” of the child seat.

[0005] This danger is avoided or reduced by a child seat of the invention in that, in the event of a crash-caused deceleration of the vehicle, a limited displacement of at least the backrest of the child seat in the driving direction takes place in order to compensate the child's displacement within the child-seat-side belt system. As a result, the child is held in an unchanged tight contact with the child-seat-side belt system and the child seat. This results in a higher safety for the child, in addition to the advantages achieved by the ISOFIX connection.

[0006] Although from European Patent Document EP 0 927 659 A2, an arrangement of a child seat on a vehicle seat by way of an ISOFIX system is known. In the case of the known arrangement, a deformation element is provided between the vehicle seat and the child seat, by means of which deformation element, peak loads in the detent device and/or fastening device of the ISOFIX system are to be reduced. As a result of the relative movement of the child seat with respect to the vehicle seat caused during a deforming of the deformation element, force peaks are reduced as they occur in the event of the impact of unsecured cargo on the rear seats of the backrest of the vehicle seat.

[0007] In contrast, in the case of the present invention, devices are provided at the child seat which permit a relative movement (of the backrest) of the child seat with respect to the child-seat-side fastening device, in which case, however, the child-seat-side belt system remains rigidly connected with the fastening device in order to restrain the child as best as possible. In contrast, as a result of the deformation element according to European Patent Document EP 0 927 659 A2, the child-seat-side belt system participates in the same manner in the limited forward displacement caused by the deforming of the deformation element as the entire child seat, with the initially mentioned disadvantages mentioned concerning the prior art.

[0008] The invention is preferably implemented by a displacement of the entire child seat with respect to the vehicle seat. However, to achieve the advantages of the invention, it is sufficient to permit a displacement of the backrest alone.

[0009] The vehicle-side belt system is formed, for example, by a lap belt with a catch tray. The invention has a particularly advantageous effect with respect to such a system because the increased wedging of the child according to the invention limits the forward displacement and reliably prevents a “pulling-out” of the child during the rebound. By means of the invention, it is also possible to bring a child seat with a catch tray into a sleeping or comfort position in which the backrest of the child seat has a larger inclination angle with respect to the seat surface so that the distance between the backrest and the catch tray is enlarged. The displacement (of the backrest) of the child seat permitted according to the invention in the event of a crash ensures a still sufficient wedging of the child in the child seat also in the sleeping or comfort position.

[0010] In principle, the invention can also be used in the case of child seats with a child-seat-side multipoint belt system without a catch tray with a 5-point belt system. It also has an advantageous effect in the case of child seats whose multipoint belt system is displaced with the child seat in the event of a crash, because energy can additionally be reduced by the devices for displacing the backrest of the child seat, for example, an expandable slot or a shear bolt.

[0011] Possible embodiments of the invention are illustrated in the drawing and will be explained in detail in the following.

[0012] FIG. 1 is a lateral view of a known arrangement of a child seat on a vehicle seat by means of a vehicle-side belt system;

[0013] FIG. 2 is a view of an arrangement according to the invention corresponding to FIG. 1; and

[0014] FIG. 3 and 4 are enlarged sectional views of details of the invention.

[0015] FIG. 1 illustrates a vehicle seat 1 on which a child seat 3 is fastened in a conventional manner by a vehicle-side or seat-side belt system 2, preferably a three-point arrangement. The child seat 3 as well as the child (not shown) are held by the belt system 2. In addition, a catch tray 4 is placed into the belt system. In the event of a crash-caused deceleration of the vehicle, a displacement of the child seat 3 in the driving direction FR takes place which is illustrated by the broken lines. Although this displacement by the distance s (because of the belt slack and the stretching of the belt strap of the belt system 2) impairs the course of the deceleration affecting the child, it maintains the child's wedging between the catch tray 4 and the “moving-up” backrest 7 of the child seat 3.

[0016] FIG. 2 illustrates an arrangement of a child seat 3 according to the invention by means of a fastening device corresponding to the ISOFIX Standard. On both sides of the child seat 3, the fastening device 5 has two elongated locking elements 6, the open end sections 8 of which engage with ISOFIX adapters on the vehicle seat 1 (not shown). The child is held on the child seat 3 by means of a child-seat-side belt system 9 with a catch tray 4.

[0017] As a result of the rigid ISOFIX connection, in the event of a vehicle crash, the backrest 7 of the child seat 3 remains in the initial position A with respect to the vehicle seat 1 which is illustrated by means of the solid lines. With respect to the above, caused by the crash, a certain forward displacement of the child in the driving direction FR takes place, although it is reduced with respect to the conventional systems according to FIG. 1. This forward-displacement reduces the wedging of the child in the child seat 3.

[0018] According to the invention, the fastening device 5 and the child seat 3 are constructed such that, in the event of a crash-caused deceleration of the vehicle, they permit a limited displacement of the child seat 3 in the driving direction FR by the distance s, whereby the child seat 3 takes up the position V. The fastening device 5 itself does not participate in the displacement so that the child-seat-side belt systems fastened to the fastening device 5 remains rigidly connected to the vehicle seat 1.

[0019] According to the embodiment of FIG. 3, a slot 10 extending in the driving direction FR is provided in a section 17 of the fastening device 5, in which slot 10 a child-seat-side bolt 11 engages. In the normal operation of the vehicle, the bolt 11 is held in the initial position A as illustrated in FIG. 3, because a narrowing 12 adjacent to the end of the slot 10 facing away from the driving direction prevents a displacement of the bolt 11 in the slot 10. When a defined limit value of the vehicle deceleration, as it is reached during a vehicle crash, is exceeded, because of the acting inertial forces of the child seat 3 and of the child secured thereby, the bolt 11 widens the narrowing 12 and moves along the slot 10 to the end-side stop 13.

[0020] As a result, the child seat 3 moves forward by the distance s, as is indicated by a broken line in FIG. 2, with the advantage of an increased wedging of the child in the child seat 3. The narrowing 12 is to be dimensioned such that the forces occurring in the normal driving operation do not cause a displacement of the bolt 11 in the slot 10.

[0021] FIG. 4 illustrates another embodiment of the invention, which has a bolt 14 fixing the child seat 3 to a section 19 of the fastening device 5. The bolt 14 has a desired breaking point 15 which is arranged in the area of an opening 16 of the section 19. When a defined crash-caused vehicle deceleration is exceeded, the bolt 14 designed as a shear bolt is severed and thus releases the child seat 3 for a limited displacement in the driving direction FR. The bolt 14 is simultaneously held in another, not shown guide, so that the displacement in the driving direction FR is limited.