Injection system having skirt walls forming an annular seal walls

Injection system comprising:

• a manifold plate having at least one nozzle configured for injecting a flow of molten material in a mould cavity;
• a hot runner manifold configured for supplying said nozzle with the flow of molten material, wherein said nozzle is compressed between said manifold and said manifold plate;
• a valve stem for controlling the flow of molten material through said nozzle, wherein at least one part of said valve stem passes through said manifold;
• an actuator having a piston cylinder and a piston that is slidable in a sealed manner within said piston cylinder to open and close said valve stem;
• and
• a back plate, wherein said piston cylinder is compressed between said back plate and said manifold, whereby a compression load is transmitted between said back plate and said manifold through said piston cylinder so as to close at least one seal zone for an operating fluid of said actuator;
• wherein said injection system comprises a first skirt wall connected to said piston cylinder and a second skirt wall connected to said manifold, said first and second skirt walls being coupled together to allow mutual axial sliding movement of said skirt walls along an annular seal zone in a direction parallel to said valve stem.