Hammer protection system and method

A hydraulic hammer comprising:

• a housing;
• a piston arranged for reciprocating motion within the housing when the hydraulic hammer is run;
• a fluid inlet configured to receive pressurized fluid for running the hydraulic hammer;
• a fluid outlet for discharging hydraulic fluid from the hydraulic hammer;
• a bypass passage fluidly connecting the fluid inlet and the fluid outlet, the bypass passage having a bypass inlet fluidly connected to the fluid inlet and a bypass outlet fluidly connected to the fluid outlet;
• and
• an automatic shut-off valve disposed in the bypass passage between the bypass inlet and the bypass outlet and configured to open or close the bypass passage, the automatic shut-off valve including:
• a cavity,
• a first chamber fluidly connecting the bypass inlet to the bypass outlet,
• a spool provided in the cavity, the spool being movable within the cavity between an open position to fluidly connect the bypass inlet to the bypass outlet and a closed position to fluidly disconnect the bypass inlet from the bypass outlet, an intermediate cavity and a first orifice being defined in the spool, the first orifice extending from the intermediate cavity to a second chamber, and
• a second chamber to hold a volume of fluid against the spool to restrict movement of the spool from the closed position towards the open position based on a flow of the volume of fluid from the second chamber,
• wherein the first orifice is configured to allow the flow of the volume fluid from the second chamber at a restricted rate to delay movement of the spool from the closed position towards the open position by a set time.

A method of protecting a hydraulic hammer, the hydraulic hammer having a fluid inlet for receiving a pressurized fluid for running the hammer and a fluid outlet to discharge fluid from the hydraulic hammer, a bypass passage fluidly connecting the fluid inlet to the fluid outlet, and an automatic shut-off valve positioned in the bypass passage and configured to open or close the bypass passage, the automatic shut-off valve comprising a spool provided in a cavity and movable in the cavity between a closed position to close the bypass passage and an open position to open the bypass passage, the automatic shut-off valve being biased towards the closed position, an intermediate cavity and a first orifice being defined in the spool, the first orifice extending from the intermediate cavity to a second chamber, and the first orifice being configured to allow flow of the volume of fluid through the first orifice from the second chamber at a restricted rate and thereby delay movement of the spool from the closed position to the open position under pressure of the pressurized fluid by the set time, the method comprising:

• operating the hammer by providing the pressurized fluid through a passage connected to the fluid inlet and simultaneously moving the automatic shut-off valve from the closed position towards the open position under pressure of the pressurized fluid during a predetermined amount of continuous run time;
• delaying movement of the automatic shut-off valve from the closed position to the open position for the predetermined amount of time by restricting movement of the spool by allowing fluid positioned between the spool and a check valve to pass through the first orifice defined in the spool at a restricted rate of flow;
• and
• stopping the hydraulic hammer when the spool reaches the open position by opening the bypass passage.