Abstract:
The safety bumper includes: (a) a bumper basic body ( 4 ) having a forward surface; (b) a bumper bar ( 5 ); (c) a mounting member ( 11 ); (d) a cross-bar ( 10 ) of the vehicle, (e) at least one of a deployable energy-absorbing element ( 9; 32, 33, 39, 41; 52, 60 ) positioned above the mounting member ( 11 ) and a deployable energy-absorbing element ( 17, 20; 38, 46; 64 ) positioned below mounting member ( 11 ); and (f) an impact sensor ( 6 ) located in bumper bar ( 5 ). The bumper bar ( 5 ) is connected to bumper basic body ( 4 ) and extends through to the forward surface of bumper basic body ( 4 ), bumper bar ( 5 ) is also connected to mounting member ( 11 ), and mounting member ( 11 ) is located behind bumper basic body ( 4 ) and bumper bar ( 5 ). The mounting member ( 11 ) is connected to cross-bar ( 10 ), which is located behind mounting member ( 11 ). The deployable energy-absorbing elements are controlled by impact sensor ( 6 ), and upon actuation thereby are deployed and form (either singly or together) a substantially continuous contour and a substantially common front together with the forward surface of bumper basic body ( 4 ).

Description:
CROSS REFERENCE TO RELATED PATENT APPLICATIONS 
     The present patent application claims the right of priority under 35 U.S.C. §119 (a)-(d) and 35 U.S.C. §365 of International Application No. PCT/EP00/03159, filed Apr. 10, 2000, which was published in German as International Patent Publication No. WO 00/64707 on Nov. 2, 2000, which is entitled to the right of priority of German Patent Application No. 199 18 202.7, filed Apr. 22, 1999. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to a safety bumper system for motor vehicles, in particular for private and commercial vehicles, which is constructionally fashioned in such a way that it meets the requirements of the current pedestrian protection test, e.g. according to the regulations of the European Enhanced Vehicle Safety Committee (EEVC), but at the same time permits external configuration possibilities as in conventional bumper systems. 
     BACKGROUND OF THE INVENTION 
     Known bumper systems of private and commercial vehicles endeavour to satisfy various requirements with regard to the absorption of energy in the event of accidents both at low and higher speeds while nevertheless retaining some creative scope for the design. The bumper for the front or tail region of a private vehicle known from EP 768 213 A2 comprises a shock absorber as an energy-absorbing element, which is connected by an easily mountable fastening to the actual bumper and to a covering provided thereon. 
     From EP 839 690 A2 a bumper system for commercial vehicles is known, which is composed substantially of combined channel section strips, which have special reinforcing elements. Said bumper system is used, on the one hand, to absorb energy in the event of collision with other motor vehicles. On the other hand, with the assembly below an existing bumper an undershoot guard is achieved. 
     EP 736 420 A2 describes a bumper system for a private vehicle, which has a bumper substantially comprising an energy-absorbing buffer, which is surrounded by a flexible enclosure and which in the event of a collision deforms and in so doing absorbs the kinetic energy. 
     All known bumper systems are however not capable of meeting the current requirements regarding pedestrian protection in the event of an accident involving pedestrians. 
     In particular, bumper systems are required to satisfy the requirements e.g. of the EEVC (European Enhanced Vehicle Safety Committee) directive. This states i.a. that the impact of a legform impactor—which recreates the form of the human leg—with a weight of 13.6 kg and at a speed of 40 kph against the front portion of the motor vehicle is to be tested. The acceleration occurring during the test is to be no greater than 150 g/m 2 . The buckling angle of the impactor during the test should not exceed 15° and the shear distance of the impactor parts is to be no greater than 6 mm. 
     In addition to the pedestrian protection conditions, it is moreover desirable for the bumper system to satisfy the requirements of the 4 kph impact test and the 8 kph impact test. 
     There is moreover the need for design freedom to be, as far as possible, only slightly restricted by fulfillment of the EEVC requirements. The overall appearance of the motor vehicle is not to be influenced or is to be influenced only minimally by the protection measures. 
     SUMMARY OF THE INVENTION 
     It has been discovered that the new bumper systems described below not only pass the 4 kph test (optionally also the 8 kph test) but also meet the above-mentioned pedestrian protection conditions. What is more, by virtue of the invention, design freedom for configuration of the front or rear of motor vehicles is extensively retained. 
     The subject matter of the invention is a safety bumper for a motor vehicle, in particular for a private vehicle, at least equipped with a bumper basic body plus bumper bar, which is connected by a mounting, in particular by an energy-absorbing module as the mounting, to a cross-bar of the vehicle, characterized in that above the mounting energy-absorbing elements and/or below the mounting energy-absorbing elements are provided, which are controllable by an impact sensor, and after actuation by the impact sensor form above and/or below the bumper basic body a continuous contour with the front side of the bumper basic body. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 a  is a sectional representation of a safety bumper according to the invention; 
     FIG. 1 b  is a sectional representation of the safety bumper of FIG. 1 a  after an impact and deployment of the air bags; 
     FIG. 1 c  is a sectional representation of a safety bumper similar to that of FIG. 1 a , in which the mounting member ( 11 ) is a plastic strut body; 
     FIG. 2 a  is a sectional representation of a further safety bumper according to the invention with upper and lower lifting systems, and top and bottom sliding plates; 
     FIG. 2 b  is a sectional representation of the safety bumper of to FIG. 2 a  after an impact and deployment of the lifting systems; 
     FIG. 3 a  is a sectional representation of a further safety bumper according to the invention with two airbags, in which the lower air bag is located beneath a lowermost part of the bumper; and 
     FIG. 3 b  is a sectional representation of the safety bumper of FIG. 3 a  after an impact and deployment of the air bags. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Here, continuous contour means that in the event of an impact-triggered actuation of the energy-absorbing elements the latter together with the front side of the bumper basic body form a common front, which reduce the buckling angle—in relation to the impact of a standard-leg impactor—and keep it e.g. at less than 15°. This then conforms with the provisions of the initially mentioned guideline of the EEVC. 
     In a preferred construction, the energy-absorbing element disposed above the mounting is an airbag, which is provided in a folded-up state, preferably under a flap, on or behind the mounting and the igniter of which is electrically connected by the control line to the impact sensor. 
     In a preferred variant, the energy-absorbing element disposed above the mounting is an airbag, which is provided in a folded-up state, preferably under a movable top flap, on or behind the mounting and the igniter of which is electrically connected by the control line to the impact sensor and which together with the opened top flap after actuation by the impact sensor forms a continuous contour with the front side of the bumper basic body. 
     A further special variant of the bumper is characterized in that the energy-absorbing element disposed above the mounting is a combination of a top bumper flap, a sliding plate situated below the latter and a lifting system plus drive, wherein the drive is electrically connected by the control line to the impact sensor, and wherein after actuation of the drive by the impact sensor the extended top bumper flap and the extended sliding plate ( 48 ) form a continuous contour with the front side of the bumper basic body. 
     In a preferred construction of the invention, the energy-absorbing element disposed below the mounting is an airbag, which is provided in a folded-up state, preferably below the lowermost part of the bumper, and the igniter of which is electrically connected by the control line to the impact sensor. 
     A further preferred variant of the bumper is characterized in that the energy-absorbing element disposed below the mounting is an airbag, which is provided in a folded-up state, under a movable bottom flap, and the igniter of which is electrically connected by the control line to the impact sensor and which together with the opened flap after actuation by the impact sensor forms a continuous contour with the front side of the bumper basic body. 
     In another special form of construction, the energy-absorbing element disposed below the mounting is a combination of a bottom bumper flap, a bottom sliding plate situated below the latter and a bottom lifting system plus drive, wherein the drive is electrically connected by the control line to the impact sensor, and wherein after actuation of the drive by the impact sensor the extended bottom bumper flap and the extended bottom sliding plate form a continuous contour with the front side of the bumper basic body. 
     The drive for the bottom and/or for the top lifting system is independently of one another in particular a gas pressure cylinder or a hydraulic cylinder. 
     Instead of the top or the bottom lifting system an airbag system may be provided for moving the top or bottom bumper flap. 
     The said flaps, the top flap, the top bumper flap, the bottom bumper flap or the bottom flap, which hide the energy-absorbing elements from sight and swing open upon actuation of the sensor, are independently of one another movably connected by a flexible plastic part, in particular made of the material TPE or TPU, to the bumper basic body. Conventional hinges may also be used. 
     The mounting of the bumper is preferably an energy-absorbing plastic foam body or plastic strut body. 
     In a particularly preferred manner the energy-absorbing plastic foam body is made of polyurethane foam or thermoplastic foam material, e.g. polystyrene foam or polypropylene foam. 
     Particular advantages regarding energy absorption upon impact arise when the energy-absorbing elements situated above the mounting and/or the energy-absorbing elements below the mounting are connected by an additional supporting strut to the front end of the motor vehicle. 
     The essential features of the present invention are: the classic bumper system is extended in a way that both retains design freedom and satisfies pedestrian protection requirements. 
     In principle, the described safety bumper operates as follows: energy absorption is effected by the outer skin of the bumper system made of plastics material in conjunction with a constructionally fashioned mounting made of plastics material or metal. This may be a foam system or a plastic or metal strut body or a combination of both. Said system is intended to satisfy the requirements regarding the maximum acceleration values. 
     To satisfy the further requirements regarding pedestrian protection (buckling angle e.g. less than 15° and shear distance e.g. less than 6 mm), a swing-out top and bottom part are provided e.g. above and/or below the mounting in the outer plastic shell. 
     Said flap mechanism may be realized by a “hard/soft combination” of suitable plastics materials or by the possibilities afforded by the construction and/or material of the outer plastic shell alone (hinge function). 
     Outward swinging of the top and bottom parts is effected e.g. by means of fundamentally known airbag systems, mechanical lifting apparatuses or pressure cylinders, which are tripped by pressure sensors and/or contact-free sensors (radar, ultrasound, laser or the like). Said sensors should be controlled in particular in a speed-dependent manner. For example, from a vehicle speed of 0 kph up to around 4 kph the sensors do not respond. This serves as a protection against abuse of the airbag systems or against superficial damage. 
     The flap mechanism may be so designed that the parts involved (flaps) may be reversibly opened and closed a plurality of times. 
     Materials, which may be considered for the outer bumper shell (front side), are plastics materials which permit a minimum wall thickness with simultaneous retention of the mechanical properties over a wide temperature range. For the less rigid components of the swing-open top and bottom flap mechanisms, TPU (thermoplastic polyurethane) or TPE (thermoplastic elastomer) is recommended. 
     In order to meet the pedestrian protection requirements, besides the already provided cross-bar additional structural components may be provided for the purposes of support and stiffening. Said additional structural components are preferably realized by plastic/metal composite parts (e.g. of polyamide+sheet metal). In the event of overload, built-in predetermined buckling points provide crash damage protection. 
     The invention is described in detail below with reference to the drawings. 
     EXAMPLES 
     Three examples show various forms of construction of the invention. 
     Example 1 
     Bumper System 
     FIGS. 1 a  and  1   b  each show a cross section through a safety bumper. Below the bonnet  1  of a private vehicle a part of the outer boundary of the bumper is connected by a hinge  2  to the flap  3 . The hinge  2  allows the flap  3  to swing open in the direction of the bonnet  1  (as depicted by folded-back flap  18  of FIG. 1 b ). Selectively, instead of the hinge, a connecting piece  2  made of elastic material, e.g. a two-component compound (a thermoplastic polyurethane: TPU), is provided. A folded-up airbag  9  is provided below the flap  3 . The bumper basic body (outer bumper shell)  4  and the bumper bar  5  surround the energy-absorbing module (mounting)  11 , a polyurethane foam cushion, and a cavity situated underneath, in which a further airbag case  14  containing airbag  15  is accommodated. 
     The flap  3 , the bumper basic body  4  and the bumper bar  5  are manufactured from a plastics material (polycarbonate/polybuteneterephthalate mixture: PC/PBT) or a polyalcohol formulation. Situated behind the bumper bar  5  is a sensor  6 , which via an electronic signal through the line  12  trips the ignition of the airbags  9  and  15  in the event of a collision with the bumper (the igniters of the airbags  9  and  15  are not illustrated here). Situated below the sensor  6  is a further flap  16 , which like the top flap is connected by a second hinge  7  to the basic body  4  and which may open in a downward direction. 
     Swinging-open of the flap  16  is likewise tripped via an airbag  15 . The unfolded airbag  17 , together with the flap  16  ( 20  in FIG. 1 b ) and the components  13  and optionally  22 , effects the energy absorption in the bottom region of the bumper and reduces the buckling angle and the shear distance of the front of the private vehicle. 
     The airbag  15  is supported via a plastic/metal composite part  13  and  14  (of polyamide/sheet steel), which in turn is integrated in the cross-bar  10  or at the front end  21  of the car. 
     The energy absorption in the middle part is effected via a system comprising the basic body  4  and the energy-absorbing foam cushion (EA foam)  11 . 
     In the event of an accident, the unfolded airbag  19  effects the energy absorption in the region above the bumper and considerably reduces the buckling angle. 
     By means of the flap mechanism in the bottom part and by means of the airbag  19 ,  17  the buckling angle is kept below 15° and the shear distance is kept at less than 6 mm (see FIG. 1 b ). 
     For the additional support of the airbag  15  and the transmission of impact energy a further connecting bar  22  may be installed from the airbag  15  to the front end  21  of the car. 
     In the event of a crash, an anti-overload device in the connecting bar  22  provides protection against the destruction or damage of built-on parts. A buckling point may be provided in the form of a bead in the construction. A further possibility is the reduction of the bar cross section by means of through-holes or reduction of the wall thickness. 
     Example 2 
     FIGS. 2 a  and  2   b  each show a cross section through an alternative safety bumper. FIG. 2 a  shows a bumper system, in which in the course of a collision a top lifting system  41  pushes a top flap  32  upwards (flap  49 ) and a bottom lifting system  46  pushes a bottom flap  38  downwards (flap  47 ). 
     Provided above the energy absorber  11  is a lifting apparatus  41 , which carries the top sliding plate  33 . The top sliding plate  33  is situated under the flap  32 , which is movably connected by the elastic hinge  2  to the bumper basic body  4  and at its top end abuts the bonnet  1 . 
     The bumper bar  5  with the impact sensor  35  is situated on the bumper basic body  4 . Provided below the energy absorber (mounting)  11  is a bottom lifting apparatus  46 , which carries the bottom sliding plate  47 . The sensor  35  is connected by the electrical sensor lines  12  to a top and a bottom gas pressure cylinder  39  and  44 , which effect the movement of the lifting apparatuses  41  and  46 . 
     The displacement of the flaps  32  and  38  is triggered by the sensor  35  in the bumper bar  5  in a similar manner to the triggering of the airbag ignition in the bumper system according to Example 1. 
     The trigger signal is supplied via the sensor lines  12  to movable pressure cylinders  39  and  44 . The latter effect the rapid movement of the lifting systems  41  and  46 . Instead of the lifting systems  41  and  46  it is possible to use vertically installed pressure cylinders (not illustrated). A further possibility is displacement of the sliding plates  33  and  38  by means of expanding airbags (not shown). 
     The energy absorption in the middle part of the bumper is effected as in Example 1. 
     By virtue of the extending of the bottom flap  32  and the top flap  38  the buckling angle for an impacting body is kept below 15° and the shear distance is kept at less than 6 mm (see FIG. 2 b ). 
     The materials of the bumper basic body  4  and of the flaps  32  and  38  correspond to the materials described in Example 1 (PC/PBT mixture and polyalcohol formulation). The hinge  2  is made of TPU. 
     Example 3 
     FIGS. 3 a  and  3   b  each show a cross section of a further variant of the safety bumper. FIG. 3 a  shows a bumper system, in which in the course of a collision by means of a top and bottom airbag system  60  and  64  a top flap  68  ( 52 ) is opened and a uniform impact front is formed. 
     Provided above the energy absorber  11  is a top airbag system  60 , which is seated below the top flap  68 . The top flap  68  is movably connected by the elastic hinge  2  (made of TPU) to the bumper basic body  4  (made of a PC/PBT mixture) and at its top end abuts the ornamental moulding  58  below the bonnet  1 . 
     The bumper bar  5  with the impact sensor  6  is situated on the bumper basic body  4 . Provided below the energy absorber  11  is a bottom airbag apparatus  64 , which is disposed under the bottom set-back part of the bumper basic body  4 . The sensor  6  is connected by the electrical sensor lines  12  to the top airbag system  60  and the bottom airbag system  64 . The bottom airbag system  64  is mounted on the bottom end of a bar  63 , which carries the entire bumper and the bottom, externally visible part  57  of the bumper. Situated above the part  57  is an air inlet opening. 
     For the additional support of the airbag  66  and transmission of impact energy a further connecting bar  22  may be installed from the airbag  66  to the front end  21  of the car. 
     The ignition of the igniters of the top airbag system  60  and bottom airbag system  64  is triggered by the sensor  6  in the bumper bar  5  in a similar manner to the triggering of the airbag ignition in the bumper system according to Example 1. 
     The trigger signal is supplied via the sensor lines  12  to the airbag systems  60  and  64 . 
     The energy absorption in the middle part of the bumper is effected in the manner illustrated in Example 1. 
     By virtue of the expansion of the top airbag  67  the flap  52  is opened—in a comparable manner to opening of the top flap in Example 1. 
     In the bottom part the expanded airbag  66  fills the bumper contour in such a way that a uniform, kink-free front is produced. By said means and by means of the top airbag  67  combined with the flap  52  the buckling angle of the entire impact front is kept below 15° and the shear distance is kept at less than 6 mm (see FIG. 3 b ). 
     Support of the bottom airbag  66  is effected in a comparable manner to Example 1 via a plastic/metal composite structure (polyamide/sheet steel) attached to the cross-bar  10  or to the front end  21 . 
     In the event of a crash, an anti-overload device in the optionally additionally provided connecting bar  22  provides protection against the destruction or damage of built-on parts.