1. An injection device for administering a liquid medicine to a patient, comprising a fixed assembly comprising a first gear element, a movable assembly comprising a container of liquid medicine, means for displacing the liquid medicine from said container for administration to the patient, and a second gear member mounted to engagement with the first gear element, a driving element configured to actuate one of said first and second gear elements, and coupling means configured to maintain engagement between the first and second gear elements under normal conditions, and to disengage the first and second gear elements under impact in a predetermined direction, wherein the movable assembly is movable relative to the stationary assembly in a predetermined direction by gearing between the first and second gear elements. 2. An injection device according to claim 1, wherein said one of the first and second gear elements, the gear element is made in the form of a gear wheel, and the other gear element of the first and second gear elements is made in the form of a gear rack. An injection device according to claim 1, wherein the driving element is mounted on a fixed unit, and said one gear element of the first and second gear elements is the first gear element. The injection device according to claim 2, in which the driving element is mounted on a fixed unit, and the specified one gear element from the first and second gear elements is the first gear element.1. Инъекционное устройство для введения пациенту жидкого лекарственного средства, включающее неподвижный узел, содержащий первый зубчатый элемент, подвижный узел, содержащий емкость с жидким лекарственным средством, средства вытеснения жидкого лекарственного средства из указанной емкости для его введения пациенту и второй зубчатый элемент, установленный с возможностью зацепления с первым зубчатым элементом, приводящий элемент, выполненный с возможностью приведения в действие одного из указанных первого и второго зубчатых