Device and method for preventing high back pressure of inner cavity of plunger pump shell

The invention discloses a device and method for preventing high back pressure of an inner cavity of a plunger pump shell. A hydraulic control one-way valve is installed between the inner cavity of theshell and an oil suction cavity of a valve plate, an unloading valve is installed between the valve plate and an oil tank, and the unloading valve is communicated with the oil suction cavity of the valve plate. The shell is driven to rotate, and a plunger is driven to slide in the shell. When the back pressure of the oil suction cavity is small, an unloading valve element is closed, the hydrauliccontrol one-way valve is closed, oil in the shell enters the oil suction cavity, and the pressure of the inner cavity in the shell is reduced. When the back pressure of the oil suction cavity is large, the unloading valve element is opened, the hydraulic control one-way valve is opened, oil in the shell enters the oil tank through the oil suction cavity and the unloading valve element, and the pressure of the inner cavity