Active-passive dual mode switchable vehicle suspension system and switching method therefor

An active-passive dual mode switchable vehicle suspension system, comprising

• a filter, a hydraulic pump, a one-way valve, a power take-off, a servo valve, a suspension cylinder, an overflow valve, an energy accumulator, a reversing valve, a first pressure sensor, a second pressure sensor, a controller, an oil tank and a displacement sensor;
• wherein
• the filter has an oil inlet communicated with the oil tank through an oil pipe, and has an oil outlet communicated with an oil inlet of the hydraulic pump through an oil pipe;
• the hydraulic pump has an oil outlet communicated with an oil inlet of the one-way valve through an oil pipe, the one-way valve has an oil outlet communicated with an oil inlet of the servo valve through an oil pipe, and the servo valve has a return port communicated with the oil tank through an oil pipe;
• the hydraulic pump has a drive shaft connected to the power take-off, and the power take-off is connected to a power output shaft of a vehicle engine;
• the servo valve is a three-position four-way electro-hydraulic servo valve, comprising three states of a left position, a middle position and a right position;
• the servo valve has a first working oil port communicated with a rodless cavity of the suspension cylinder, and a second working oil port communicated with a rod cavity of the suspension cylinder;
• when the servo valve is at the middle position, all passages between the oil inlet and return ports of the servo valve and the first working oil port and second working oil port of the servo valve are turned off, when the servo valve is at the left position, a passage between the oil inlet port of the servo valve and the first working oil port of the servo valve is turned on, and a passage between the return port of the servo valve and the second working oil port of the servo valve is turned on;
• when the servo valve is at the right position, a passage between the oil inlet port of the servo valve and the second working oil port of the servo valve is turned on, and a passage between the return port of the servo valve and the first working oil port of the servo valve is turned on;
• the suspension cylinder is hinged to the vehicle body, and the suspension cylinder is provided with the displacement sensor;
• the overflow valve has an oil inlet communicated with an oil outlet of the one-way valve through an oil pipe, and an oil outlet communicated with the oil tank through an oil pipe;
• an opening pressure of the overflow valve is adjusted in such manner that a control signal is given by the controller to a control end of the overflow valve;
• the reversing valve and the servo valve are arranged in parallel, the reversing valve has an oil inlet communicated with the oil tank through an oil pipe, and a return port communicated with the oil inlet of the overflow valve through an oil pipe;
• the first working oil port of the reversing valve is communicated with the rod cavity of the suspension cylinder through an oil pipe, and the second working oil port of the reversing valve is communicated with the rodless cavity of the suspension cylinder through an oil pipe;
• the energy accumulator is arranged in an oil path between the return port of the reversing valve and the oil inlet of the overflow valve;
• the first pressure sensor is provided in an oil path between the energy accumulator and the return port of the reversing valve, and the second pressure sensor is provided in an oil path between the rodless cavity of the suspension cylinder and the first working oil port of the servo valve;
• and
• a control signal output end of the controller is respectively connected with a control end of the power take-off, a control end of the servo valve, a control end of the overflow valve and a control end of the reversing valve.