BRAKING METHOD FOR INTERNAL-COMBUSTION ENGINE

PURPOSE:To adjust the opening time of a starting air valve and improve braking performance, by adjusting size of an air hole and its length or the like of a rotary plate in a control valve which controls opening and closing timing of the starting air valve serving as an opening and closing valve feeding braking air into a cylinder. CONSTITUTION:An internal-combustion engine has a starting air valve 3 forming an opening and closing valve when braking air is fed into a cylinder 16, control valve 4 controlling opening and closing timing of the starting air valve 3 and a pilot pipe 24 connecting each of these valves 3, 4. Now if a cam shaft 5 rotates, air 31, being allowed to flow passing through an air hole 22 of a rotary plate 21 in the control valve 4 from a starting air main pipe 15, is fed to the starting air valve 3. Then the starting air valve 3, being opened by moving a valve rod 13 of a piston 12, feeds high pressure air 32 from the main pipe 15 into the cylinder 16. Here an opening time of the starting air valve 3 is continued to the time after the top dead center by adjusting, for instance, hole size, hole length, etc. of air hole 22 or an air relief hole 23 of the control valve 4.