Apparatus for producing ultrahigh pressure water jet

Claim 1

An ultrahigh pressure water apparatus, provided with a drive source for a pump, an ultrahigh pressure pump driven by said drive source and adapted to receive feed water, impart increased pressure to said feed water, and discharge said water at increased pressure, and a nozzle gun adapted to receive ultrahigh pressure water emanating from said ultrahigh pressure pump and project said ultrahigh pressure water in the form of beams, which apparatus is characterized in that said ultrahigh pressure pump comprises: a cylinder, a piston disposed inside said cylinder so as to be reciprocated parallelly to the axis of said cylinder, a feed water pipe adapted to supply water to the interior of said cylinder and disposed near the end plate of said cylinder so as to communicate through a check valve with the interior of said cylinder, a discharge water pipe adapted to discharge ultrahigh pressure water from inside said cylinder and disposed near the end plate of said cylinder so as to communicate through a check valve with the interior of said cylinder, a piston hole formed in the surface of said piston opposed to said end plate in the axial direction of said piston substantially at the axial position thereof, a free piston rotatably disposed inside said piston hole parallelly with the axis thereof, an oil collecting recess formed annularly on the peripheral surface of said piston and adapted to communicate with said piston hole, a first O-ring fitted around the peripheral surface of said free piston, a second O-ring fitted around the peripheral surface of said piston on said end plate side of said oil collecting recess, a piston ring interposed between said piston and said cylinder on the side opposite said end plate of said oil collecting recess, and lubricating oil filling said oil collecting recess and said piston hole.