The correct operation of a Rexroth piston pump

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In a hydraulic system, the hydraulic pump serves as the power element, and it goes through several processes during operation. Let’s first take a look at the working process of the Rexroth piston pump during operation. 　　During operation, a Rexroth plunger pump goes through roughly three processes: oil intake, oil supply, and oil return. Oil intake process: When the protrusion of the cam rotates a certain amount, the plunger moves downward under the force of the spring; this creates a vacuum in the space above the plunger (referred to as the pumping chamber). Once the upper surface of the plunger opens the oil inlet hole in the plunger sleeve, diesel fuel contained in the oil passages of the pump’s upper part enters the pumping chamber through this hole. When the plunger reaches its lower dead center, the oil intake is complete. 　　Fuel supply process: When the cam shaft rotates to the point where the protrusion of the cam lifts the roller body, the plunger spring is compressed, causing the plunger to move upward. As a result, the fuel is under pressure, and some of it flows back through the fuel holes into the oil chamber in the upper part of the fuel injection pump. When the top surface of the plunger covers the upper edge of the oil passage in the sleeve, the small clearance between the plunger and the sleeve turns the pumping chamber at the top of the plunger into a sealed oil chamber. As the plunger continues to rise, the oil pressure in this pumping chamber increases. When this pumping pressure exceeds the force of the outlet valve spring plus the remaining pressure in the high-pressure oil pipe, the outlet valve is pushed open, and high-pressure diesel enters the high-pressure oil pipe through this valve, where it is then injected into the combustion chamber via the injectors. 　　Oil return process: The plunger supplies oil upward; when it moves up to the inclined groove on the plunger (the point where oil supply stops) and aligns with the oil return hole on the sleeve, the low-pressure oil circuit in the pumping chamber comes into communication with the central hole, the radial holes, and the inclined groove on the plunger head. As a result, the oil pressure drops sharply, and the outlet valve closes automatically due to the force of the spring, thereby preventing further oil supply. Thereafter, the plunger moves upward again; once the protrusion of the cam has rotated a bit, the plunger moves downward under the action of the spring. At this point, the next cycle begins. 　　In operation, the Rexroth plunger pump relies on the cams on the fuel injection pump’s camshaft, along with the action of the pump spring, to cause the plungers within the pump to move up and down back and forth. This movement facilitates the intake, supply, and discharge of oil – and this is the working principle of the Rexroth plunger pump.