Mercedes-benz Aktiengesellschaft

Daimler Chrysler Ag

Daimler-benz Ag

Johann Kramer

Rainer Renz

Martin Schlegl

Bruno Teusch

Bernd Schroder

Martin Tebbe

Dieter Jenuwein

bumper arrangement for a motor vehicle includes a bumper mounted in such a way that it can be moved between a rest position and an operating position. A spring acts on the bumper and is prestressed in the rest position. A locking device holds the bumper in the rest and/or operating position. A control unit actuates the locking device as a function of signals from an accident detection sensor system. When the locking device is unlocked, the spring moves the bumper abruptly into the operating position in which the bumper absorbs impact loads resulting from relative velocities up to a predetermined limit in a substantially elastic manner.

Bumper arrangement

A damping body for damping periodically alternating loads uses a shape-memory alloy material to govern the damping. The damping body is sintered from metal grains or is laminated from a plurality of perforated sheet-metal layers. The individual sheet-metal layers are orientated transversely or parallel to the loading direction and are connected to one another over the full surface area. A combination formed from a multiplicity of round pins orientated parallel to the loading direction and having enclosed gussets can also be used as a damping body. A certain hollow-space portion inside the damping body can also be created by drilling, slitting or grooving. The proportion of the open pore or bore volume of the damping body to the total volume is at least 5%, preferably about 15 to 40%. On account of the hollow spaces integrated in the damping body, multiaxial stress states impairing the damping behavior can be effectively avoided or at any rate reduced even in an unfavorably flat or wide configuration of the damping body.

Metallic damping body

A metallic damping body for damping shock-type and/or periodically changing stresses, consists of a shape-memory alloy material for effecting the damping. In order to be able to achieve a high damping effect even under a high mechanical stress on the damping body, the shape-memory alloy is selected such that it is in a state of austenitic microstructure at the operating temperature of the damping body. A sufficiently high mechanical prestress is applied to the damping body so that the damping working range is within the range of the pseudoelastic strain which starts below the proportionality limit in the stress/strain diagram of the shape-memory alloy. When the damping body is compressively stressed, a multiplicity of closely adjacent, small, uniformly distributed voids are present in the interior thereof, which together make up at least about 5%, preferably about 15 to 40%, of the total volume of the damping body. This allows free movement of the material particles in the region of the individual grain boundaries even in the interior of the damping body.

Shape-memory metallic alloy damping body

A cylindrical standard shank is provided for rotating cutting tools for locating a standard shank in a cylindrical location opening, precisely produced with regard to shape and true-running accuracy, in the work spindles of so-called transfer lines or of, for example, steep-taper adaptors. The cutting tool is, in turn, fixed by a cylindrical press connection in the standard shank serving as an adaptor between the tool shank and standardized location opening. The standard shank has, at the front, a longitudinally slotted clamping sleeve accurately machined on the inside and outside. The clamping sleeve is clamped by an accurately machined shrink collar of shape-memory alloy which is approximately the same length and has at least the same wall thickness, is present in the austenitic structural state at room temperature and in the process is reduced in diameter on account of suitable pretreatment, and bears tightly against the periphery of the clamping sleeve. The shrink collar can be transformed into the martensitic structural state by undercooling and can thereby be widened in diameter, as a result of which the clamping sleeve is relieved and the cutting tool located in the standard shank can be exchanged.

Standard shank and method for directly locating rotating cutting tools

The invention concerns a clamping tool for non-positive and high-precision clamping of workpieces by means of an expansion element, which is held inside the clamping tool and, in the unclamped state, is matched to the workpiece with little play but movably, and to which force may be applied radially over a large area. When force is applied, the expansion element expands reversibly, and bears non-positively against the workpiece, and holds it in place with high rotational accuracy and high clamping force. In order to be able to permit a high expansion rate of the expansion element in conjunction with a closed configuration of the latter, the invention proposes for the expansion element a so-called shape memory alloy, which is operated in the austenitic state with reversible stress-inducible possibility of change of the microstructure into the martensitic state. For this reason, the workpiece can also be matched to the clamping tools with substantially coarser tolerances, and this has a favorable influence on the production costs.

Clamping tool for non-positive and high-precision clamping of workpieces

An internal combustion engine is described which comprises a main combustion chamber and a secondary combustion chamber which is arranged in the cylinder head of the internal combustion engine and is connected via a shot channel to the main combustion chamber. To increase the high-temperature stability, the parts of the secondary combustion chamber which are acted upon by the hot gas jet are made of a material of intermetallic phase.

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Leonberg, Germany

Johann Kramer