Patent ID: 9724813
Date: 2017-08-08
CPC Classifications: B25D,E21B

Claim:
1. A valveless hydraulic impact mechanism for use in equipment for at least one of rock and concrete machining, said valveless hydraulic impact mechanism comprising a machine housing with a cylinder bore, a piston mounted to move within the cylinder bore and arranged to carry out repetitively reciprocating motion relative to the machine housing during operation, said reciprocating motion delivering impacts directly or indirectly onto a tool connectable to the equipment for machining at least one of rock and concrete, a driving medium at a predetermined impact mechanism pressure p, and wherein the piston includes a driving part that separates a first and a second drive chamber formed between the piston and the machine housing, and wherein the first and second drive chambers are arranged such that they include during operation the driving medium under pressure, and wherein the machine housing further includes channels that open out into the cylinder bore and are arranged such that the channels include the driving medium during operation, and that with the aid of the piston, during said reciprocating motion in the cylinder bore, the channels open onto and close from one of the first and second drive chambers such that said one of said first and second drive chambers acquires a periodically alternating pressure for maintaining the reciprocating motion of the piston, and that positions for the opening of the channels axially in the cylinder bore and for opening and closing of the channels along parts of the piston are adapted to maintain said one of said first and second drive chambers closed for the supply or drainage of the driving medium that is present in the one of said first and second drive chambers along a distance between an opening of a first said channel associated with a first turning point of the piston and an opening of a second said channel associated with a second turning point of the piston, and that the motion of the piston along said distance continues during the compression or expansion of the volume of said one of said first and second drive chambers, wherein said volume has been further adapted in order to achieve a predetermined change in pressure along the said distance, wherein the total volume V of the first and second drive chambers, including volumes that are in continuous connection with one and the same drive chamber during a complete cycle of a stroke, has been dimensioned to be inversely proportional to the square of the impact mechanism pressure p, and further proportional, with a constant of proportionality k, that has a value in the interval 5.3-21.0, to the product of the energy E of the piston in the impact against the tool and the modulus of compressibility β of the driving medium, according to the equation V=k*β*E/p 2 .