Hydraulic fluid actuated percussion tool

Claim 2

A hydraulic fluid actuated percussion tool comprising a housing forming a cylinder, a hammer piston reciprocable in the cylinder between a forward percussion stroke and a rearward rebound stroke to deliver percussion energy to a work tool, a first variable volume pressure chamber in said cylinder for urging the piston forward during the percussion stroke defined between the piston and the cylinder, a second variable volume pressure chamber in said cylinder for urging the piston rearward during the rebound stroke defined between the piston and the cylinder, valve means connected to a source of pressurized hydraulic fluid and to said first chamber by first passage means and to said second chamber by second passage means for cyclically pressurizing and draining said chambers to receiprocate the hammer piston, a first accumulaTor connected to said first passage means and to said first pressure chamber for storing kinetic energy from the rearward rebound strokes of a predetermined normal percussion force of the piston and reversing it to the forward percussion strokes, a second fluid accumulator connected to said first pressure chamber at a point located rearwardly of the connection of said first passage means to the first pressure chamber, said second accumulator being normally inactive to reciprocate the piston at the motive pressure of the hydraulic fluid while being effective to reverse said piston to the forward percussion stroke at pressures higher than the motive pressure of the hydraulic fluid, produced by the hammer piston overtravelling its normal rearward reversing point so as to cover said first passage means when rebounded by a percussion stroke exceeding the normal percussion force.

Claim 3

A tool as claimed in claim 1 in which said passage for supplying fluid to said first pressure chamber and the passage to the first accumulator terminate in a common annular groove in the cylinder.

Claim 4

A hydraulic fluid actuated percussion tool comprising a housing forming a cylinder, a hammer piston reciprocable in the cylinder between a forward percussion stroke and a rearward rebound stroke to deliver percussion energy to a work tool, a first variable volume pressure chamber for urging the piston forward during the percussion stroke defined between the piston and the cylinder, a second variable volume pressure chamber for urging the piston rearward during the rebound stroke defined between the piston and the cylinder, hammer piston controlled distribution valve means connected to a source of pressurized hydraulic fluid, to the first pressure chamber by means of a first connection passage, and to the second pressure chamber by means of a second connection passage, the distribution valve means having a first position in which it pressurizes the first connection passage and drains the second and a second position in which it drains the first connection passage and pressurizes the second connection passage, the hammer piston actuating the valve means to shift from the second position to the first position while moving rearward during the rebound stroke and actuating the valve means to shift from the first to the second position when close to its impact position, a first accumulator connected to said first supply passage for storing kinetic energy from the rebound strokes of the piston of a predetermined normal percussion force and reversing it to the forward percussion strokes, a second fluid accumulator connected to said first pressure chamber at a point located rearwardly of the connection of said first supply passage to the first pressure chamber and being normally inactive at the motive pressure of the hydraulic fluid while effective to reverse said piston to its forward percussion stroke at pressures higher than the motive pressure of the hydraulic fluid, produced by the hammer piston overtravelling its normal rearward reversing point so as to cover said first passage means upon rebound from a percussion stroke exceeding the normal percussion force.

Claim 5

A hydraulic fluid actuated percussion tool comprising a housing forming a cylinder, a hammer piston reciprocable in the cylinder between a forward percussion stroke and a rearward rebound stroke to deliver percussion energy to a work tool, a first variable volume pressure chamber for urging the piston forward during the percussion stroke defined between the piston and the cylinder, a second variable volume pressure chamber for urging the piston rearward during the rebound stroke defined between the piston and the cylinder, hammer piston controlled distribution valve means connected to a source of pressurized hydraulic fluid, to the first pressure chamber by means of a first connection passage, and to the second pressure chamber by means of a second connection passage, the distribution valve means having a first position in which it pressurizes the first connection passage and drains the second and a second position in which it drains the first connection passage and pressurizes the second connection passage, the hammer piston actuating the valve means to shift from the second position to the first position while moving rearward during the rebound stroke and actuating the valve means to shift from the first to the second position when close to its impact position, a first accumulator connected to said first supply passage for storing kinetic energy from the rebound strokes of the piston of a predetermined normal percussion force and reversing it to the forward percussion strokes, a second fluid accumulator connected to said first pressure chamber at a point located rearwardly of the connection of said first supply passage to the first pressure chamber and being normally inactive at the motive pressure of the hydraulic fluid while effective to reverse said piston to its forward percussion stroke at pressures higher than the motive pressure of the hydraulic fluid, produced by the hammer piston overtravelling its normal rearward reversing point so as to cover said first passage means upon rebound from a percussion stroke exceeding the normal percussion force.

Claim 6

A tool as claimed in claim 3 in which said supply passage for supplying fluid to said first pressure chamber and the passage to the first accumulator terminate in a common annular groove in the cylinder.