Abstract:
An energy absorbing device for carrying a passenger seat; the device comprises a base fixed to a vehicle; a member displaceable from base; at least one energy-absorbing arrangement interconnecting base and displaceable member. The energy-absorbing arrangement comprises a plastically deformable absorbing element in response to stresses greater than a predetermined threshold stress. In some embodiments the plastically deformable absorbing element is a helically configured ribbon having spaced-apart ribbon laps. In other embodiments the plastically deformable absorbing element is compressible, and/or extendable. A method of attenuating the acceleration applied to a passenger due to impact is disclosed; the method comprises steps of: providing an energy absorbing device fixedly attaching the base to the vehicle; fixedly attaching the passenger seat to the base; accidently applying the impact to the vehicle; displacing the displaceable member relative to the base; attenuating the effect of the impact on the passenger.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a passenger safety seat for use in vehicles or other mobile applications, designed to limit horizontal occupant accelerations. 
     BACKGROUND OF THE INVENTION 
     In vehicle collisions a chief cause of injury is the extreme impulses experienced; the human body has a limited ability to cope with accelerations experienced over given durations of time. For example, the US Federal Motor Vehicle Safety Standards specify maximum allowable measures listed in  FIGS. 1   a  and  1   b.    
     To lower the maximum impulse experienced, the distance through which the body travels when changing its initial to final velocity must be increased, or equivalently, the time during which the acceleration is experienced must be increased. For example, in a head-on collision of a vehicle with a rigid wall, the occupant&#39;s body will undergo a change from the vehicle&#39;s initial speed to zero speed within a certain distance. The acceleration undergone is determined by the initial velocity and this distance. If this distance can be increased, the acceleration will be decreased. Care must be taken that the passengers will experience the maximum possible acceptable impulse or less, which can be accomplished by use of energy-absorbing elements of suitable design, devices to increase the travel available to the occupant, or both. The ideal energy absorber connecting a passenger to the rest of a vehicle transmits the maximum acceptable stress to the occupant or less, reaching this level after a minimum of travel. It would transmit this level of stress and no more, no matter the level of stress imparted to it. 
     Solutions known from the prior art provide shock absorbing seats based on different types of elastic or plastic deformation or breakage of metallic components, collapsible bar mounts or columns made of metals and/or composite materials, crushable honeycomb, etc. Some available solutions present a full system including both an original seat and a built-in integrated absorbing mechanism. 
     U.S. Pat. No. 5,685,603 discloses an apparatus for a vehicle includes a child seat for holding a child. A support device supports the child seat on a seat of the vehicle for movement relative to the seat during a collision in which at least one condition exceeds a predetermined threshold. An energy absorbing device absorbs kinetic energy of the child and the child seat during such relative movement. The support device may include support bars that permit sliding movement of the child seat relative to the support bars and the vehicle seat. Several types of energy absorbing devices may be used, including compressible bellows, cut able strips of sacrificial material, crushable pieces of sacrificial material, deformable projections, a payout device with webbing, compressible shock absorber assemblies, and slid able frictionally engaging portions. 
     U.S. Pat. No. 5,152,578 a front leg is formed by an upright support rod extending vertically above a fixing stud, a rear leg is formed by both a lower support rod extending on a diagonal line joining the upper end of the front leg and the lower end of the rear leg and an upper support rod contiguous to the lower support rod in an upper position relative to the lower support rod, the upper support rod being curved accurately and inclined rearward and upwards, and an energy absorber is mounted bridge wise as a diagonal member between the upper end portion of the front leg and the lower end portion of the rear leg, to constitute a leg structure. Accordingly to this leg structure, a striking energy is absorbed by an anti-plastic deformation force induced when the rear leg and the energy absorber is deformed plastically under an impact larger than a predetermined value, and the seat is held at its supported posture in normal use. This leg structure can be utilized not only in aircraft but also in automobiles and railway vehicles. 
     A major difference between the current invention and the prior art is the ability to determine the exact position of the system under any give load and direction of the load. In the prior art, different impacts will apply different forces on the energy absorbing components. Greater load applied on the rear leg, will change the orientation of the seat differently than forces applied mainly on the front leg. 
     The change in orientation will affect the forces transferred to the occupant from the energy absorbing components (legs and cylinder). 
     Thus, if a simple, analytical and repeatable system is desired with optimized energy absorption mechanism, it is better to use a system with only one deforming component (i.e. spiral). 
     Designing a system with specific force-deflection curve which transfers predetermined forces to the occupant requires careful design of the mechanism and the use of a highly controllable EA element such as the spiral. 
     US Patent application 20030209926 discloses a child seat device formed of a base to be placed on a seat of a car, a child seat body placed on the base, and a connecting member for connecting a rear bottom of the child seat body to a fixed portion. The connecting member increases a length thereof while absorbing a kinetic energy of the child seat body when a tension higher than a predetermined value is applied thereto from the child seat body. 
     Hence there is a long felt and unmet need to provide a simple and cheap vehicle passenger safety seat which absorbs energy in tension and compression suitable for mass production. 
     SUMMARY OF THE INVENTION 
     It is hence one object of the invention to an energy absorbing device adapted for carrying a passenger seat. The aforesaid device comprises (a) a base fixedly attached to a pre-existing vehicle; (b) a member displaceable relative to the base; and (c) at least one energy-absorbing arrangement interconnecting the base and displaceable member. 
     It is a core purpose of the invention to provide the energy-absorbing arrangement comprises a plastically deformable absorbing element in response to stresses greater than a predetermined threshold stress. 
     Another object of the invention is to disclose the plastically deformable absorbing element which is a helically configured ribbon having spaced-apart ribbon laps. 
     A further object of the invention is to disclose the plastically deformable absorbing element which is compressible or extendable. 
     A further object of the invention is to disclose the base connected to the vehicle by means of a connector meeting ISOFIX 13216. 
     A further object of the invention is to disclose the energy-absorbing arrangement comprising a hingely interconnected four-bar sub-arrangement configured be reshaped angularly when the device is stressed; angular reshaping is controlled by the deformable element secured to the base and connected to the four-bar sub-arrangement. 
     A further object of the invention is to disclose the energy-absorbing arrangement comprising a slideway and a slide linearly displaceable along the slideway; linear displacement of the slide relative to the slideway is controlled by the deformable element interconnecting the slideway and slide. 
     A further object of the invention is to disclose the slideway comprising two orthogonal rails configured for sliding the slide in two orthogonal directions. 
     A further object of the invention is to disclose the slideway comprising a plurality of rails configured for sliding the slide in a plurality of directions angularly different from each other. 
     A further object of the invention is to disclose the energy-absorbing arrangement comprising a turning arrangement configured for a smooth rotation of the displaceable member. 
     A further object of the invention is to disclose the energy-absorbing arrangement comprising a six-bar-hinged sub-arrangement configured for controllable linear displacement. The sub-arrangement has an axis of symmetry passing through two opposite hinges. The deformable element ties the opposite hinges. 
     A further object of the invention is to disclose the displaceable member configured for carrying a driver/passenger seat. 
     A further object of the invention is to disclose the seat connected to the base by means of at least one belt. 
     A further object of the invention is to disclose the seat comprising a seat back. 
     A further object of the invention is to disclose the plastically deformable absorbing element which is made by means of technology selected from the group consisting of casting, injecting, eroding, molding, wire twining, machining, forming, bending and any combination thereof. 
     A further object of the invention is to disclose the plastically deformable absorbing element selected from the group consisting of: an elongated spiral, a crushable column, a rolling torus, an inversion tube, a cutting shock absorber, a slitting shock absorber, a tube-and-die absorber, a rolling absorber, a flattening-tube absorber, a strap bender absorber, a rod bender absorber, a wire bender absorber, a wire-through-platen absorber, a deformable link absorber, an elongating a tube/strap/cable absorber, a tube flaring, a housed coiled cable absorber, a bar-through-die absorber, a hydraulic absorber, a pneumatic absorber and combinations thereof. 
     A further object of the invention is to disclose a method of attenuating the acceleration applied to a passenger due to impact. The aforesaid method comprises steps of: (a) providing the device comprising (i) a base fixedly attached to a pre-existing vehicle; (ii) a member displaceable relative to the base; and (iii) at least one energy-absorbing arrangement interconnecting the base and displaceable member; (b) fixedly attaching the base to the vehicle; (c) fixedly attaching the passenger seat to the base; (d) accidently applying the impact to the vehicle; (e) displacing the displaceable member relative to the base; and (f) attenuating the effect of the impact on the passenger. 
     It is another core purpose of the invention to provide the step of attenuating the effect of the impact on the passenger performed due to plastic deformation of the energy absorbing element in response to stresses greater than a predetermined threshold stress. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1   a  presents a proposal for allowable chest acceleration and deflection levels, depicting ranges of acceleration and deflection acceptable for human subjects. 
         FIG. 1   b  presents a table of acceptable injury criteria. [Development of Improved Injury Criteria for the Assessment of Advanced Automotive Restraint System (National Highway Traffic Safety Administration, 1998)] 
         FIGS. 2   a  and  2   b  are views of the energy absorbing component of the current invention. 
         FIG. 3  is an exemplary graph of the force (y-axis, in Newton) vs. travel (x-axis, in mm) of one embodiment of the energy absorbing component of the current invention. 
         FIG. 4   a  is an exemplary graph of the necessary force vs. travel required of an energy absorbing component to cause an output acceleration within the allowable parameters given by the human body endurance graph, for an occupant of average weight, when installed in a standard four-bar mechanism. 
         FIG. 4   b  superimposes the curves of  FIG. 3  and  FIG. 4   a  for purposes of comparison. 
         FIGS. 4   c  and  4   d  superimpose desired and actual accelerations for purposes of comparison. 
         FIGS. 5   a - 5   c  illustrates energy absorbing slides. 
         FIGS. 6   a  to  6   c  illustrate the base system; 
         FIGS. 7   a  and  7   b  illustrate fixedly attaching the base system to the vehicle seat; 
         FIG. 8  illustrates the base system provided with the rotatable member; 
         FIGS. 9   a  and  9   b  illustrate the child seat mounted onto the base system; 
         FIGS. 10 to 13  illustrate the four bar energy absorbing mechanism; 
         FIGS. 14 and 15  illustrate the energy absorbing element embedded into the commercially available baby seat; 
         FIGS. 16   a  and  16   b  illustrate the embodiment of the invention adapted for an adult passenger; 
         FIGS. 17 to 20  illustrate the embodiment of the invention provided with four-bar mechanism and a transverse slide; 
         FIG. 21  illustrates the embodiment of the invention provided longitudinal and transverse slides; 
         FIGS. 22 to 23  illustrate the embodiment of the invention provided with frame energy absorbing mechanism; 
         FIGS. 24 to 25  ( a  and  b ) illustrate the embodiment of the invention provided with frame and four-bar mechanisms; 
         FIGS. 26 to 28  illustrate the embodiment of the invention provided with the transverse rail mechanism; 
         FIGS. 29 to 34  illustrate the embodiment of the invention provided with the multidirectional energy absorbing mechanism; and 
         FIGS. 35 to 39  illustrate the embodiment of the invention provided with the rotating mechanism. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The invention discloses a vehicle passenger seat having an improved impact performance. In an embodiment suitable for children, the seat is composed of two parts, a stationary base and a sliding seat. The sliding seat slides on a linear slide that is attached to the stationary base. The stationary base is preferably restrained by means of the existing passenger seat belts of the vehicle, and the passenger is restrained to the sliding seat by means of additional seat belts attached to the sliding seat. The sliding seat is restrained from free motion by means of an energy-absorbing element. In an embodiment suitable for adults, the seat is made of a single section that is connected to the vehicle by means of the aforementioned energy absorbing element. 
     When a vehicle undergoes impact, it may experience a large acceleration which for human beings can often be injurious or fatal. The acceleration experienced depends upon the difference between initial and final velocities and the distance over which the acceleration occurs, 
     
       
         
           
             
               
                 
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                         v 
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                       2 
                       ⁢ 
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                   Equation 
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                   1 
                 
               
             
           
         
       
     
     Where Δv is the change in velocity, d is the distance over which the acceleration occurs, and a is the acceleration experienced. It will be seen that for a given Δv (which in many cases cannot be controlled, as in a crash where a car goes from cruising speed to zero) the acceleration experienced will be decreased by increasing d. Thus allowing the passenger of a vehicle as large a degree of travel within the vehicle body as possible may decrease the accelerations experienced to a less-injurious level. Similarly if the energy of the impacting object can be reduced, its velocity will be reduced and Δv will be decreased. In a seat intended to carry an infant, the available travel d is limited, ultimately by the distance to the front seats. Thus given some initial and final velocities, the acceleration transmitted over the distance d should be the maximum level acceptable without causing injury, to minimize the required travel and therefore volume of the system. By designing the system this way one decreases the probability of a sudden injurious acceleration when the device reaches the end of its travel. 
     In  FIG. 1   a , maximum acceptable acceleration and chest compression levels are presented as developed by the National Highway Traffic Safety Administration in 1998.  FIG. 1   b  presents the maximum injury levels: Head Injury Criterion (HIC) of 1000; 60 G&#39;s of acceleration and 76 millimeters of chest deflection; 10,000 Newtons of force on the femurs, neck injury criteria of Compression of 4000 N, Tension of 3300 N; Shear of 3100 N; Flexion of 410 Nm; and Extension 125 Nm, thorax (rib and spine) acceleration of 85 to 90 g, and allowable pelvic criterion 130 g. One may appreciate from these data that injury can be avoided if the accelerations are low enough and/or the durations or compressions are small enough that the ‘injury zones’ of  FIG. 2   a  are avoided. It will be understood by one familiar with the field that this is a representative graph, and different regions may become evident with different research. 
     In an embodiment suitable for children, the invention discloses a vehicle passenger chair composed of two parts, a stationary base and a sliding seat. The sliding seat slides on a linear slide that is attached to the stationary base. The stationary base is preferably restrained by means of the existing passenger seat belts of the vehicle, and the passenger is restrained to the sliding seat by means of additional seat belts attached to the sliding seat. The sliding seat is restrained from free motion by means of an energy absorbing element, which for example may comprise a spring-like helical element that deforms under tension in a precisely controlled and tested manner. This helical element can be designed that it delivers only the maximum allowable acceleration to the sliding seat, and no more, thereby reducing the accelerations experienced by the passenger. 
     A possible energy absorbing element is now described. This is a spring like helical element that stretches in a predictable way under tension. One embodiment of this device is shown in  FIGS. 2   a - 2   b . The retaining holes  101  are used to install the member  100 . In the embodiment of  FIGS. 2   a  and  2   b , a varying cross section  103  is employed. The member  100  is designed for use in tension, and will be deformed plastically when a high enough force is applied to it. The “plastic” regime refers to a range of stress for which deformation without subsequent retraction will occur, as opposed to the spring-like “elastic” regime of stress wherein a body will generally return to its original configuration. When this stress level is met or exceeded, a deformation of the member will occur. This deformation consists of an ‘unwinding’ of the device along the helical cut  105 . To relieve the twist undergone by the device as well as relieving the stress concentration at the end of the helical cut, strain relief slots  102  ( FIGS. 3   c  and  3   d ) are employed in the preferred embodiments. Other forms of provision for stress relief will be obvious to one skilled in the art. Furthermore, it is within provision of the invention that rotation of the energy absorbing member either be prevented or allowed to a predetermined degree, therefore allowing control over the force-vs.-travel curve of the device. 
     It should be understood that the plastic deformation region is only reached when the force applied to the energy absorbing element is greater than a certain threshold. When the applied force exceeds this threshold, only the threshold force is transmitted by the device to the rest of the system it is protecting. This threshold force can be fixed by varying the cross section of the device, or after a given wall thickness has been produced, by varying the pitch of the helical cut  105 . The helical cut  105  can be carried out after mass production of the mechanisms, allowing parameters of the device such as ultimate travel length and threshold reaction force to be varied according to need, after mass production of the energy-absorbing element. Another advantage of the current invention over the prior art is that the rest of the system is reusable. The energy absorbing device is the only part to experience plastic deformation; this device can be replaced. 
     With reference to  FIG. 3 , one can appreciate the different regimes of the force vs. travel curve of one possible energy-absorbing member of the current invention, namely the spiral member of  FIGS. 2   a  and  2   b . In the elastic regime  301 , the device behaves in a spring-like fashion, with a linear relation between applied force and travel, and with return of the element to its original configuration after removal of the applied force. In the plastic regime  302 , which is reached rather quickly, after little travel, the force one can apply to the element remains largely constant, rising only slightly with continuing deformation of the energy-absorbing member. In the end regime  303  the force increases more and more rapidly with continuing displacement. The characteristic of a short elastic regime and a plastic regime lasting the maximum length of travel allowable is desirable in this system, since this way almost no travel is ‘wasted’ without providing a reaction to the applied force. Furthermore, nearly the entire travel provides the almost the exact required reaction force, as calculated in the theoretical design, as shown in the graph ( FIG. 6   b ). Obviously this graph is appropriate to a particular embodiment and other graphs will be desirable in different situations (such as different mounting points—wall or floor, different expected acceleration range, and the like). The plateau region of the graph has the desirable effect of transmitting the force of the impact without causing injury, while absorbing as much impact energy as theoretically possible, decreasing the probability of a sudden injurious acceleration when the device reaches the end of its travel. This sudden acceleration would occur if not enough impact energy was absorbed; it is for this reason that the maximum allowable acceleration should be transmitted, without exceeding this amount. It will be appreciated by one skilled in the art that the relation depicted in  FIGS. 4   a  and  4   bb  is non-trivial and quantitatively different from the force-displacement curve one would obtain with a simple metallic rod, spring, or the like. It should also be appreciated that the exact form of the curve, including the maximum travel, and the value of the applied force during the plastic regime, can both be tuned easily by changing the length of the energy-absorbing device, the pitch of the helical cut, the cross section size and shape, material, installation method, and design of the mechanical system into which the energy-absorbing element is placed. 
     The absorbing component is made of a plastically-deforming material such as but not limited to plastic, low carbon steels, stainless steels, composite materials, and others as will be obvious to one skilled in the art. The use of plastic for a child seat may be particularly apt since the masses involved in limiting a child-seat acceleration are relatively low, the mass of the child being perhaps 10-20 kg and the mass of the ‘sprung weight’ of the seat being similar. One embodiment of the energy absorption component takes a helical spring-like form, designed to experience plastic deformation over a desired deformation length, under a desired impact load threshold. The operating characteristics [namely the stress-strain curve, and thus the deformation length impact load threshold and acceptable load range for the system to be protected] of the mechanism can be controlled by the following parameters:
         Element cross section shape and thickness;   Winding pitch [number of revolutions per length];   Length; and   Material       

     A device incorporating one or more of the energy absorbing components of the current invention will also be tunable by changing the number of energy absorbing components used and the mechanical design of the system into which the energy absorbing component(s) is/are placed. 
     One advantage of the invention is that it can be installed as part of an add-on component to an existing, original vehicle seat, just as a common vehicle baby seat is installed on top of an existing car seat and is restrained by the existing restraining belts. The solution can be tailored to fit several different types of seats and vehicles, and as described above, different impact load behaviors can be easily arranged. The device parameters are affected by several factors including: platform structure and weight; available clearance from the seat ahead; expected occupant size and mass, and the like. 
     When placed in a suitable assembly, the force-displacement curve of the energy-absorbing element required to produce the desired force-displacement curve on the seat and occupant will take a form like that shown in  FIG. 4   a . A comparison of the desired profile of  FIG. 6   a  with the actual (measured) profile is shown in  FIG. 4   b . One sees that the profile provided is nearly exactly the theoretically desired curve. This verifies the correct operation of the device as can be determined by simulation. 
     For ‘real’ proof of correct operation, the device must be tested under actual impact. The device is placed into a test fixture that impacts the device with a predetermined load. The test fixture measures input and output accelerations and records them. The correct operation of the device under actual impact is shown clearly in the experimentally measured curves of  FIGS. 4   c  and  4   d . These figures are graphs of measured acceleration vs. time for sled-tests in which sleds holding accelerometers are accelerated. As shown in  FIGS. 4   c  and  4   d , the accelerometer is attached to a seat that is attached to the sled by way of the restraint of the current invention. As is clear from the figures, the accelerometer restrained by the current invention indeed undergoes a reduced acceleration. 
     A curve  401  shows a temporal dependence of the measured input acceleration applied to a vehicle body by a sled upon which the device is accelerated. A curve  402  presents a temporal dependence of the measured output acceleration of the seat which is connected to the sled by means of the energy absorbing member. 
     Another useful aspect of the system lies in the fact that due to the plastic deformation of the energy absorbing element(s), rebound is minimized (unlike the case for example if using a spring, which after being compressed/extended will tend to return to its initial state). Rebound energy is absorbed by further distortion of the energy absorbing element, generally into an S-shape. This is a very useful characteristic since the added acceleration of any rebound forces will increase the danger to the occupant. In fact the energy absorbing device of the invention has a tendency to absorb any rebound due to the rest of the system since even after being stretched to its maximum extent, it tends to resist being pushed back to a less-stretched position. In practice it becomes bent into an ‘S’ shape that will resist compression to some degree and absorb the rebound forces of the system. The seat mechanism may be installed directly on the vehicle seat by means of the vehicle restraining belt. Alternatively the device may be adapted to fit into a base that is itself attached to the vehicle e.g. by means of the restraining belts, or an additional bracket. This bracket may be attached to the roof, seat, floor, or other point of the vehicle. This embodiment may be found advantageous to decrease the loads transmitted to the shock-absorbing seat, since the roof or floor will experience a lesser load due to energy absorption of the vehicle frame (which includes crush zones, for example). This will act to dampen the impact transmitted to the seat attachment bracket and reduce the impulse delivered to the rest of the vehicle. Thus from the standpoint of energy delivery, it may be advantageous to attach the seats to the floor or even the roof of the vehicle, these being points as far as possible from the point of impact. On the other hand from the standpoint of installation practicality, it may be advantageous to attach the seat to the existing seat of the vehicle. It will be appreciated by one skilled in the art that the present invention allows for all of these installation options. 
     In a preferred embodiment the seat travels on a slide or rails. Advantages of using a mechanism of this sort include simplicity, no requirement for accurate bearings or bases, and low cost. In  FIGS. 5   a - 5   c  an example of rails adapted for use in the current invention is shown. As will be obvious to one skilled in the art, any mechanism allowing forward motion can be used instead of the linear rails used in this particular embodiment. For example motion along a curved path leading fore and downward will tend to increase the distance of the occupant from the dashboard during collisions. Furthermore, the linear slide itself can form an energy absorbing element. For example if the rails are slightly non-parallel, as the seat slides upon the rails it will encounter increasing resistance and will tend to deform the rails and thereby dissipate energy as it moves forward. The top half  1101  is adapted to attach to a vehicle seat, which rests upon it. The top half  1101  slides upon the bottom half  1102 , which is attached to the vehicle floor, existing seat, or other point or points in the vehicle. The travel of the top half  1101  upon the bottom half  1102  is restrained by means of the energy absorbing element  1103 , which is provided with holes  1105  adapted to accept pins  1104 . As will be obvious to one skilled in the art, any energy absorbing element can be used here, including but not limited to those shown in  FIGS. 3E-Q . The pins  1104  can slide within a channel  1106 . As seen in the figure, their dispositions within the channel  1106  are such that a force upon the system, in either forward or backward directions (parallel to the direction of movement of the linear slide), can occur only by deformation of the energy absorbing element  1103 . This is true for both accelerations and decelerations, for example head-on collisions (decelerations) and rear-end collisions (accelerations).  FIG. 5   b  shows the assembled slide in its original configuration, while  FIG. 5   c  shows the assembled slide after travel of the slide (and attendant deformation of the energy absorbing element (hidden by the top half  1101 )). As detailed above, the energy absorbing component undergoes plastic deformation when subjected to tension, and the device thereby absorbs kinetic energy of impact, restraining the travel between seat and vehicle sufficiently to prevent travel longer than the length of the slide, while allowing enough travel to reduce accelerations appreciably. 
     Reference is now made to  FIGS. 6   a  to  6   c  presenting different embodiments of the base device  500 ,  500   a  and  500   b . In general view, the base device comprises a base  510  fixedly attachable to a vehicle or to vehicle passenger seat (not shown). The member  520  is displaced ably connected to the base  510 . The base  510  is attachable to the vehicle passenger seat by means of ISOFIX attaching means  530 . Ears  540  are designed for fixation of the member  520  to a backrest (not shown). 
     As seen in  FIG. 6   b , the embodiment  500   a  provides rotational displacement of the member  520  relative to the base  510  in response to an accidental shock frontal to the vehicle. A energy absorbing element  560  decreases an acceleration applied to the passenger. In FIG.  6   c , the embodiment  500   b  provides linear displacement of the member  520 . An internal energy absorbing element is not shown. 
     Reference is now made to  FIG. 7   a , presenting a general view of the base device  500  fixedly attached to a vehicle seat  570 . The base device is provided with a child seat  580  fixedly attached to the aforesaid base device. 
     Reference is now made to  FIG. 7   b , presenting a proposed arrangement. The base  510  is fixedly attached to the vehicle seat  570  by ISOFIX means  530 . The child seat  580  is mechanically linked to the ears  540  by ISOFIX means  560 . 
     Reference is now made to  FIG. 8 , showing an alternative embodiment  500   c  provided with a rotatable member  590  mounted onto the displaceable member  520 . The rotatable member is adapted for carrying a child seat. 
     Reference is now made to  FIG. 9 , presenting the base device  500   c  with the child seat  580  mounted there onto. The base device  500   c  provides rotatability of the child seat  580 . 
     Reference is now made to  FIG. 10 , presenting a baby seat connection to a car. In accordance with the present invention, the baby seat  610  is connected to the base  630  which contains the motion mechanism and energy absorption component (not shown). The base  615  is connected to a passenger seat. The passenger seat  610  is mechanically connected to the base  615  either by means of ISOFIX connection or a seatbelt connection. 
     The connection of the baby seat  610  to the base  615  can also be done by the following manners: ISOFIX connection and a specific design for a particular seat/base. The motion mechanism can be designed or 1 or 2 axis as required by the application. The specific embodiments are described below. The present invention is characterized as a substantially rigid structure in the limit of technological achievability. The aforesaid structure is connected to an energy absorbing member, which absorbs the energy of the impact. 
     Reference is now made to  FIGS. 11   a  and  11   b , presenting exemplary embodiment of the present invention. The baby seat  610  is connected to the base  630  by connecting means  627  (for example, belts). Numerals  623  and  625  refer to an ISOFIX pair of an anchor and a clip for a connection of the base  630  to the passenger seat (not shown). An anchor  621  is designed for a connection of the baby seat  610  to the base  630 . 
     Reference is mow made  FIGS. 12 and 13 , presenting a first embodiment of the present invention. The arrangements of the bar motion mechanism  640  depicted in  FIGS. 12 and 13  correspond to their positions before and after an impact, respectively. The motion mechanism  640  comprises bars  641 ,  643 ,  647  and  649  hinged to each other. As affected by an impact, the baby seat  610  displaces right ( FIG. 13 ). The energy of the impact is partially absorbed by an energy absorbing member  650  which expands under the action of the impact. A range of rotation of the bar  641  is limited by a slot  645 . The invention can be embedded into existing commercially available seat or seat base, without essential modification of the seat design. The introduction of the energy absorbing element into the seat arrangement is completely seamless to a user. 
     The energy absorbing element  650  can be selected from the group consisting of: an elongated spiral, a crushable column, a rolling torus, an inversion tube, a cutting shock absorber, a slitting shock absorber, a tube-and-die absorber, a rolling absorber, a flattening-tube absorber, a strap bender absorber, a rod bender absorber, a wire bender absorber, a wire-through-platen absorber, a deformable link absorber, an elongating a tube/strap/cable absorber, a tube flaring, a housed coiled cable absorber, a bar-through-die absorber, a hydraulic absorber, a pneumatic absorber and combinations thereof. 
     Reference is now made to  FIGS. 14 and 15 , presenting an exemplary technical solution, in which the energy absorbing element  650  is embedded into a commercially available baby seat arrangement including the seat  610  and the base  630 . The energy absorbing element  650  interconnects the parts  610  and  630 . In accordance with the preferred embodiment of the present invention, the energy absorbing element  650  comprises an expandable spiral member. The spiral member can be replaced by any device recited in the previous paragraph. 
     The main advantage of the invention is the option of embedding the energy absorbing element into any existing seat design. The energy absorbing element can be embedded either into the base itself with no changes in the seat (demonstrated here in an exemplary manner only) or into the seat itself without a need for a specific base (not shown). The change does not affect the system functionality and can be implemented by utilizing the same connection techniques and existing space environment. 
     Reference is now made to  FIGS. 16   a  and  16   b , presenting an embodiment of the invention adapted for an adult passenger  660 . The aforesaid seat is mounted onto the four-bar motion mechanism interconnected with the vehicle through the energy absorbing element  650  (preferably, a spiral). As affected by an impact, the baby seat  610  displaces right ( FIG. 16   b ). The energy of the impact is partially absorbed by an energy absorbing member  650  which expands under the action of the impact. 
     Reference is now made to  FIGS. 17 and 18 , presenting isometric and side views of a second embodiment of the invention. The motion mechanism is provided with a transverse slides  652 . The baby seat  610  is displaceable along the aforesaid slides. As affected by a transverse impact, the baby seat  610  displaces along the slider  652 . The energy absorbing element  650  interconnecting the baby seat  610  and the vehicle (not shown) absorbs at least partially the impact energy. 
     Reference is now made to  FIG. 19 , presenting arrangements corresponding to the seat positions placed onto the device depicted in the previous paragraph before and after the longitudinal impact. 
     Reference is now made to  FIGS. 20   a ,  20   b  and  20   c .  FIGS. 20   a  and  20   c  depict positions of the seat after right and left transverse impacts, respectively.  FIG. 20   b  corresponds to the seat position before the impact. 
     Reference is now made to  FIG. 21 , presenting a third embodiment of the invention. The motion mechanism is provided with tow orthogonal slides configured for displacement of the seat (not shown) along longitudinal and transverse directions in the cases as affected by the corresponding impacts. Specifically, the motion mechanism comprises longitudinal slides (not shown) and transverse slides  670 . As affected by transverse or longitudinal impact, the baby seat displaces along the slides while the energy absorbing elements  650  absorb at least partially the impact energy. 
     Reference is now made to  FIGS. 22 and 23 , presenting a forth embodiment of the invention. The seat  610  and base  615  are interconnected through a frame absorbing assembly  700  which comprises the energy absorbing element  650 . As affected by a transverse impact, the baby seat  610  displaces due to collapsing the frame  701  such that the expanded element  650  absorbed at least partially the impact energy. 
     Reference is now made to  FIGS. 24 and 25  ( a, b ) presenting a technical solution including a bar arrangement ( 641 ,  643  and  647 ) provided with the energy absorbing element  650  for protection against the longitudinal impact and the frame assemble  701  for protection against the transverse impact. 
     Reference is now made to  FIGS. 26 ,  27  and  28 , presenting a fifth embodiment of the invention. The aforesaid embodiment comprises energy absorbing mechanisms configured to absorb energy of longitudinal and transverse impacts. Specifically, a swingable bar arrangement including the bars  641 ,  643  and  647  and the energy absorbing element  650  is configured to absorb energy of the longitudinal impact. A slide  710  provided with the energy absorbing element  650  is configured to absorb energy of the transverse impact.  FIG. 28  shows the slide in two positions  710  and  710 ′ before and after the transverse impact, respectively. After the impact, the energy absorbing element  650  is in an expanded state  650 ′ 
     Reference is now made to  FIGS. 29 to 32 , presenting a sixth embodiment of the invention which comprises a multi-directional slide  720  configured for displacement of the baby seat  610  in accordance with a direction of the impact. The baby seat  610  is displaceable in a predetermined direction such that the impact energy at least partly is absorbed by the energy absorbing element  650 .  FIGS. 31 and 32  show the positions of energy absorbing element  650  and  650 ′ before and after the transverse impact. 
     Reference is now made to  FIGS. 33 and 35 , presenting additional variants of the sixth embodiment. Specifically, slides  723  and  725  are configured for absorbing energy of transverse and longitudinal impacts. 
     Reference is now made to  FIGS. 36 to 39 , presenting a seventh embodiment of the invention. The aforesaid embodiment comprises a rotatable plate  740  connected to energy absorbing elements  650 . The plate  740  is mounted onto a rotating table  730 .  FIG. 37  shows device arrangement after a front impact. Both energy absorbing elements  650 ′ are expanded. The plate  740  is not turned around.  FIG. 38  shows device arrangement after a left impact. The left energy absorbing elements  650 ′ is expanded while the right energy absorbing elements  650 ′ is not expanded. The plate  740  is angularly displaced clockwise.  FIG. 39  shows device arrangement after a right impact. The right energy absorbing elements  650 ′ is expanded while the left energy absorbing elements  650 ′ is not expanded. The plate  740  is angularly displaced counter-clockwise.