Hydraulic percussion device and construction apparatus having the same

A percussion device that breaks an object, the device comprising:

• a cylinder for housing a piston;
• a piston for reciprocating in the cylinder;
• a backward port for connecting a front chamber being located at a front side of the cylinder to a hydraulic source;
• a forward port being formed in a rear chamber being located at a rear side of the cylinder;
• a forward-backward valve for controlling forward motion and backward motion of the piston by being positioned at one of a forward position for connecting the forward port to the hydraulic source and inducing the piston to move forward and a backward position for connecting the forward port to a hydraulic discharge line and inducing the piston to move backward;
• a control line for moving the forward-backward valve to the forward position when being connected to the hydraulic source;
• a long-stroke port for connecting the hydraulic source to the control line through the front chamber when the piston is moved backward to a first position, the long-stroke port being formed between the backward port and the forward fort and being connected to the control line;
• a short-stroke port being connected to the hydraulic source through the front chamber when the piston is moved to a second position which is closer to the front side of the cylinder than the first position, the short-stroke port being formed between the backward port and the long-stroke port and being connected to the control line;
• a transmission valve being positioned between the short-stroke port and the control line and being positioned at one of a long-stroke position for disconnecting the short-stroke port to the control line and a short-stroke position for connecting the short-stroke port to the control line;
• a proximity sensor for detecting a bottom dead point of the piston when the target is broken;
• and
• a controller configured to:
• determine a breaking condition based on the detected bottom dead point and transmit a control signal to the transmission valve based on the determined breaking condition,
• wherein when the transmission valve is positioned at the long-stroke position, the piston receives a forward force from a time point when the piston is retreated back to the first position and operates as a long-stroke, and when the transmission valve is positioned at the short-stroke position, the piston receives a forward force from a time point when the piston is retreated to the second position where the piston is located before being retreated to the first position and operates as a short-stroke being shorter than the long-stroke.