the Safe design of the car (a part 2)

The Principal cause of destruction of cars and travmirovanija people at road accident are shock loadings. These loadings have pulse character and though their action is short-term, reach the big sizes because of sharp change of speed of the car. At counter collisions and car arrival on an obstacle average delay of the centre of gravity of the car can reach 40... 60 g.

For decrease in inertial loadings into a design of cars enter the elements promoting increase of duration of deformation of details. To create a protective zone round the driver and passengers, arrange a rigid skeleton in a combination with legkosminajushchimisja at blows by forward and back parts of a body (fig. 53). At counter collisions the steering mechanism is displaced back, approaching a steering wheel to the driver. At the same time the body of the driver under the influence of inertial forces sharply moves forward. As a result of blow about a steering wheel the driver can receive serious traumas of a breast, a belly cavity, and sometimes and hearts.

Zones of deformation of the car at collision

a Fig. 53. Zones of deformation of the car at collision

For protection of the driver a steering wheel nave do the big size with a soft deformable cover and utaplivajut it concerning a rim. Spokes and a rim skeleton at the big loadings are bent, softening blow about it.

Designs of safe steering managements are rather various., For example, to reduce possibility of moving and to lower the efforts perceived by a steering wheel, apply steering shaft with kardannymi the hinges deviating at blows upwards or aside, or having safe muftu, collapsing at blows.

To number of the most effective systems individual are sewn up drivers and passengers at all kinds of road accident it is necessary to carry seat belts. Application of seat belts as practice shows, in 90% of serious road accidents rescues the human life, being in the car and consequently their application is obligatory. On domestic cars the three-dot combined diagonalno-zone belt of static or inertial type is established. The size of a tension of a seat belt which in belts of static type is regulated individually for each person has special value. At normal length of a belt between a belt and a trunk of the person should pass a palm. In this case necessary deduction of the person at road accident is provided. To maintenance of automatic adjustment of a belt of inertial type apply the inertial coils involving a belt with set effort and fixed at lists, sharp acceleration and braking. Coil blocking occurs at acceleration 0,5g.

Ability of elements of a design to perceive considerable stretching efforts and to provide absorption the most part of kinetic energy of blow suffices is unitary. Therefore, for example, belts after road accident are subject to obligatory replacement as at the loadings exceeding limiting, in a belt there are the irreversible changes sharply reducing its durability and power absorbing properties.

At passing collisions passengers of the forward car often suffer. From sharp blow in the car behind the head under the influence of force of inertia leans back sharply back (fig. 55), and it can lead to damage of cervical vertebras. For protection of passengers on a seat back establish headrests with a soft upholstery. Headrests should maintain loading to 90 N.Pri it a back point of a head should not be displaced back on distance more than 10 see Under the influence of delay not less than 8 g a headrest should limit a head deviation back concerning a torso line on a corner no more than 45 °.

By operating Rules the life of the driver and passengers should be kept at car arrival on a motionless obstacle with a speed of 50,7 km/h; in case of blow behind on the car a subject in the weight equal to weight of the car, moving with a speed of 36,5 km/h, at lateral blow (at an angle 90 °) with a speed of 36,5 km/h, during time perevorachivanija the car (blow on a roof) with a speed of 10,8 km/h.

head Position at passing collision (without a headrest)

a Fig. 55. Head position at passing collision (without a headrest)

<= the previous page