High-pressure metering apparatus

A high-pressure metering apparatus for ejecting a fluid such as a polishing paste, comprising a housing having a storage chamber, a spring-loaded, stroke-adjustable compressed air piston-cylinder device with a plunger displaceable into the storage chamber, an injection nozzle, an adjustable valve device closing the storage chamber off from said injection nozzle and controlled in use by the pressure in the storage chamber, said valve device including a valve ball and a valve plate, and said housing further including a low-pressure fluid supply line leading to the storage chamber, there being a non-return valve in said low-pressure line, the storage chamber having an outlet side bounded by a piston element fixed to said housing, to which piston element said valve ball of said valve device is concentrically fixed and on which a cylinder element is displaceably mounted with the intermediary of a sealing ring, which cylinder element is closed by said valve plate of the valve device which possesses a valve seating situated opposite the valve ball and adjoining a through bore, said injection nozzle being located downstream of said valve plate and being fixed to said cylinder element the apparatus further comprising a compression spring against which said cylinder element bears and a clamping cap against which said compression spring thrusts, said clamping cap having a front opening and being screwed externally onto the housing, and there being a space bounded by said piston element, the cylinder element and the valve plate which is connected with said storage chamber via bores passing through the piston element, and the axes of symmetry of the valve device, the housing, the storage chamber, the compressed air piston-cylinder device and the plunger are in alignment, the arrangement being such that said valve plate is fixed in said cylinder element independently of said injection nozzle, which is removable by a screwed connection without adversely affecting the setting of said valve device, which screwed connection passes through said front opening of the clamping cap, and the securing in use of the piston element to the housing takes place as the clamping cap surrounding the valve device is screwed onto the housing.