Patent ID: 9328560
Filing Date: 2016-05-03
CPC Classification: E21B

Claim Text:
1. A ground-drilling device comprising: a basic body; a drill head which is supported for movement in a longitudinal axial direction relative to the basic body, wherein a free space is formed between the drill head and the basic body, and wherein a size of the free space is variable as a function of said movement; an impact piston which is moved so as to oscillate within the basic body; and a sealing element for sealing the free space against an environment and comprising at least one adjusted ventilation opening for connecting the free space with the environment, wherein the sealing element is configured as a valve element, wherein said valve element opens when an overpressure is present in the free space to thereby establish a pressure compensation, and which is closed when a negative pressure is present in the free space to thereby prevent the pressure compensation, and wherein the sealing element operates independent of the position of the drill head and the impact piston.