Hydraulic Hammer

Abstract

A piston cylinder is formed inside a ram and is fitted with a piston attached to a stationary hollow piston rod, creating a upper piston chamber for receiving pressurized hydraulic fluid, which causes the ram to rise as the volume of the upper piston chamber is expanded due to the hydraulic pressure and increasing volume of hydraulic fluid. When the ram reaches predetermined desired height, hydraulic pressure is released by opening a directional valve, allowing the ram to drop. A lower piston chamber is sealed and filled with gas. A moveable shuttle member that reciprocates up and down inside a hollow piston rod in response to the changing volume of the lower piston cylinder, facilitating the evacuation of hydraulic fluid from the upper piston chamber. An alternative embodiment uses a single fluid and has no shuttle member.

We claim: 
     
         1 . A hydraulic hammer comprising a ram and a piston cylinder formed inside said ram, a piston seated in said cylinder, with said piston fixed to a lower end of a connecting rod with an upper end of said connecting rod fixed to a support member above said ram, hydraulic means operatively connected to said ram for moving said ram between a first position and a second position and a shuttle member seated within said hollow piston rod, said hollow piston rod having an upper end fixed to a supporting member and wherein said shuttle member is free to reciprocate within said hollow piston rod. 
     
     
         2 . A hydraulic hammer in accordance with  claim 1  wherein said hydraulic means further comprises a source of pressurized hydraulic fluid operatively connected to an upper piston chamber created by a piston inserted into said cylinder and a cylinder head above said piston for creating hydraulic pressure inside said upper piston chamber and wherein said piston is fixed to a lower end of a piston rod and means for selectively relieving hydraulic fluid pressure inside said upper piston chamber. 
     
     
         3 . A hydraulic hammer in accordance with  claim 3  wherein said pressure relieving means further comprises a pressure relief tank connected to said hollow pistons rod by a pressure relief line. 
     
     
         4 . A hydraulic hammer in accordance with  claim 3  wherein said pressure relieving means further comprises a valve in a pressurized hydraulic fluid source that can be opened to allow pressurized hydraulic fluid to flow into said pressure relief line. 
     
     
         5 . A hydraulic hammer in accordance with  claim 4  wherein said pressure relief line further comprises a passageway to an upper surface of said shuttle member inside said hollow piston rod. 
     
     
         6 . A hydraulic hammer in accordance with  claim 3  wherein said source of pressurized hydraulic fluid operatively connected to said upper piston chamber further comprises a hydraulic fluid conduit tube larger in diameter than said hollow piston rod and concentric with said hollow piston rod. 
     
     
         7 . A hydraulic hammer in accordance with  claim 5  further comprising a lower piston chamber and a cavity of said hollow piston rod below a lower surface of said shuttle member that further comprises a sealed cavity that is filled with a substantially inert gas under pressure. 
     
     
         8 . A hydraulic hammer in accordance with  claim 7  wherein the volume of said lower piston chamber and said cavity of said hollow piston rod below a lower surface of said shuttle member form a variable volume cavity that varies in volume as said ram moves between said first and second positions. 
     
     
         9 . A hydraulic hammer in accordance with  claim 2  further comprising upper and lower stop members seated inside said hollow piston rod for constraining the reciprocal movements of said shuttle member. 
     
     
         10 . A hydraulic hammer in accordance with  claim 2  wherein said cylinder further comprises a sleeve having a bottom wall inserted into said cylinder with its bottom wall in contact with a bottom wall of said cylinder. 
     
     
         11 . A hydraulic hammer comprising;
 a. a ram;   b. a cylinder formed inside said ram and sealed at its lower end by a bottom wall and sealed at its upper end by a cylinder head;   c. a piston seated in said cylinder and dividing said cylinder into an upper piston chamber and a lower piston chamber;   d. a hollow piston rod having an upper end fixed to a supporting member and a lower end fixed to said piston; and   e. a shuttle member seated within said hollow piston rod, said hollow piston rod having an upper end fixed to a supporting member said shuttle member reciprocates freely within said hollow piston rod, moving up and down in response to changes in fluid pressure above and below said shuttle member.   
     
     
         12 . A hydraulic hammer in accordance with  claim 11  further comprising means for supplying hydraulic fluid under pressure to said upper piston chamber. 
     
     
         13 . A hydraulic hammer in accordance with  claim 11  further comprising a directional valve for releasing hydraulic pressure from said upper piston chamber. 
     
     
         14 . A hydraulic hammer in accordance with  claim 13  further comprising means for applying a force to a lower surface of said piston for accelerating the relief of pressure from the hydraulic fluid in said upper piston chamber and thereby accelerating the fall of said ram. 
     
     
         15 . A hydraulic hammer in accordance with  claim 14  wherein said force applying means further comprises said shuttle member. 
     
     
         16 . A hydraulic hammer in accordance with  claim 15  further comprising a sealed chamber filled with gas under pressure, with said sealed chamber comprising said lower piston chamber and a cavity in said hollow piston rod up to a lower surface of said shuttle member, with said lower piston chamber and said cavity in said hollow piston rod being in fluid communication with each other. 
     
     
         17 . A hydraulic hammer in accordance with  claim 16  wherein said gas under pressure when acted upon by a varying volume of said variable volume cavity during movements of said ram and said shuttle member provides a spring action expansion force to said lower surface of said piston to accelerate the emptying of hydraulic fluid from said upper piston chamber. 
     
     
         18 . A hydraulic hammer comprising;
 a. a ram;   b. a cylinder formed inside said ram and sealed at its lower end and at its upper end;   c. a piston seated in said cylinder and dividing said cylinder into an upper piston chamber and a lower piston chamber;   d. a hollow piston rod having an upper end fixed to a supporting member and a lower end fixed to said piston;   e. a shuttle member seated within said hollow piston rod, said hollow piston rod having an upper end fixed to a supporting member said shuttle member reciprocates freely within said hollow piston rod, moving up and down in response to changes in fluid pressure above and below said shuttle member; and   f. means for applying hydraulic fluid pressure to said upper piston chamber for raising said ram and means for relieving said hydraulic fluid pressure in said upper piston cylinder for allowing said ram to fall and means for introducing hydraulic fluid into a lower piston chamber as said ram falls for accelerating the falling of said ram.   
     
     
         19 . A hydraulic hammer in accordance with  claim 18  further comprising a receptacle attached to a lower surface of said piston and depending therefrom and a well beneath said receptacle formed in said ram whereby the volume of hydraulic fluid to be pumped is reduced. 
     
     
         20 . A hydraulic hammer in accordance with  claim 19  further comprising means for supplying hydraulic fluid under pressure to said upper piston cylinder and means for relieving the pressure on the hydraulic fluid and for emptying the hydraulic fluid from said upper piston chamber and means for applying a downward acceleration force on said ram, said accelerating means further comprising means for controlling the magnitude of said downward acceleration force.