Autoinjector

An autoinjector comprising a body that receives a reservoir, said reservoir containing fluid and including a piston and a needle, said autoinjector further comprising a piston rod that is adapted to co-operate with the piston of said reservoir, said piston rod being movable between a primed position and an injection position in which said piston rod has moved the piston of the reservoir so as to inject the fluid through the needle, an injection spring being provided for urging said piston rod towards its injection position, the autoinjector further comprising an injection lock that blocks said piston rod in its primed position, said injection lock including a control sleeve, said control sleeve containing said piston rod and said injection spring, said piston rod including a radial recess that receives at least one substantially-spherical blocking element that is movable between a blocking position and an unblocking position, said at least one blocking element being urged radially outwards by said piston rod and being held in its blocking position by a blocking ring, said blocking ring being movable relative to said piston rod so as to release said at least one blocking element and thus unblock said injection lock, enabling said injection spring to move said piston rod towards its injection position, wherein a support member is fastened to said control sleeve, said support member including a ring having an axial end that is in contact with said injection spring and the other axial end supports said at least one substantially-spherical blocking element, said blocking ring being engaged to said support member, said blocking ring being disengaged from said support member by said control sleeve when said control sleeve is moved axially while the autoinjector is being actuated, so as to unblock said injection lock.