Abstract: A filter is inserted into a cylindrical hole of a nozzle body 1. The filter has an axial blind hole, which communicates with transverse or radial holes. The transverse holes open into peripheral longitudinal trap channels, which are axially open against a collection space. Via slot-like openings, the trap channels are connected to second or clean channels, which communicate with an outlet opening of the nozzle body. A flushing opening, which can be closed by a screw, leads from the collection space to the outside. When foreign bodies have accumulated in the trap channels, the flushing opening is opened, and the foreign bodies are flushed out with an injection stroke. As a result, the foreign bodies can be removed rapidly and in a simple manner.