Patent ID: 8875853

Claim:
A hydraulic brake device comprising: a main body, a brake lever, a hydraulic rod, a connecting rod, a sleeve member and an elastic member; the main body having a hydraulic room and an assembling room, where the assembling room adjoins the hydraulic room structurally, is disposed at one end of the main body and adjoins an outside structurally, at which the hydraulic rod is inserted in the main body; one end of the brake lever pivotally assembled to the main body, the brake lever corresponding to the outside of the assembling room; the hydraulic rod movably assembled in the hydraulic room and the assembling room, the hydraulic rod having an operating head, an assembling head, a first sealing segment and a second sealing segment, the operating head being positioned in the hydraulic room, the assembling head being positioned at the outside of the assembling room, one end of the first sealing segment connected to the assembling head, another end of the first sealing segment connected to one end of the second sealing segment, another end of the second sealing segment connected to the operating head, the first sealing segment being positioned in the assembling room and having at least one sealing ring sleeved thereon, the second sealing segment being positioned in the hydraulic room and having at least one elastic ring sleeved thereon, the elastic ring contacting a wall of the hydraulic room; two ends of the connecting rod connecting to the brake lever and the assembling head of the hydraulic rod respectively; the sleeve member slidably assembled in the assembling room and sleeving onto the first sealing segment, the sealing ring contacting an inner wall of the sleeve member; and the elastic member having an assembling portion, a driving portion and a deformation portion, the elastic member being defined on the operating head, the deformation portion connecting the assembling portion and the driving portion; wherein when a user actuates the brake lever to brake a bicycle, the brake lever pushes the hydraulic rod via the connecting rod to move toward another end of the main body, so that the elastic member presses a volume of hydraulic oil into the hydraulic room; when the pressure of the hydraulic oil exceeds a threshold pressure, said pressure of the hydraulic oil pushes the driving portion of the elastic member so as to indirectly force the deformation portion to deform and bend, so that the deformation portion and the driving portion slightly move toward the assembling portion, where the deformation portion deforms to stably and smoothly brake the bicycle; when the user releases the brake lever, the pressure of the hydraulic oil decreases so that the deformation portion of the elastic member recovers elastically and the driving portion returns to its position.