Motor vehicle bumper system

A motor vehicle bumper system installed in a motor vehicle and using the flow rate of an oil circulating through an oil tank of the motor vehicle to control pressure and an accumulator to absorb energy upon a bump, comprising:

• a bumper unit, said bumper unit comprising a bumper, and parallel hydraulic cylinders controlled to move said bumper between an extended position and a retracted position;
• control switch means;
• a pump controlled by said control switch means to puimp the oil from the oil tank to said hydraulic cylinders, causing said hydraulic cylinders to move said bumper between said extended position and said retracted position;
• a pressure-setup pipe unit connected between said hydraulic cylinders, said pump and the oil tank of the motor vehicle, said pressure-set up pipe unit comprising an upper oil chamber connecting pipe connected between upper oil chambers of said hydraulic cylinders for guiding the oil into said hydraulic cylinders to retract said bumper, a lower oil chamber connecting pipe connected between lower oil chambers of said hydraulic cylinders for guiding the oil into said hydraulic cylinders to extend out said bumper, a direction control valve adapted to control the connection of said upper oil chamber connecting pipe and said lower oil chamber connecting pipe to said pump and the oil tank of the motor vehicle, a branch pipe extended from said lower oil chamber connecting pipe to the oil tank of the motor vehicle, a decompression valve installed in said branch pipe;
• and
• a pressure-relief pipe unit, said pressure-relief pipe unit comprising an accumulator, a hydraulic oil pressure sensor, a pipe having one end connected to said lower oil chamber connecting pipe and an opposite end connected to said hydraulic oil pressure sensor through said accumulator, and a relief valve installed in the pipe between said lower oil chamber connecting pipe and said accumulator;
• and
• wherein when switched on said control switch means, said decompression valve and said relief valve are closed, said direction control valve is in action, and said pump is started to pump the oil to said hydraulic cylinders to extend out said bumper, and then said decompression valve and said relief valve are opened after said bumper had been extended out;
• when switched off said control switch means, said decompression valve and said relief valve are closed, said direction control valve is reversed, enabling said hydraulic cylinders to retract said bumper.