传统的定排量机油泵在大多数发动机工况下，其泵油能力高于实际需求，导致额外的能耗损失，而变排量机油泵可以调节有效排量，从而实现降低油泵驱动功率、节省燃油的目的。选取一款2.5 L排量的柴油机开展可变排量机油泵节油潜力试验研究。试验前统计了各个零部件对机油压力的需求，并进行变排量机油泵控制特性试验，根据上述两项结果制定了机油压力控制目标。在发动机性能台架上进行变排量机油泵与模拟定排量机油泵的比较测试，结果表明，变排量机油泵倒拖扭矩减小，尤其在城市工况下，倒拖扭矩减小约2.5 N·m；而发动机万有特性油耗全部降低，其中最低燃油消耗率减少4 g/(kW·h)。在整车转毂台架上进行了整车等速油耗和中国循环油耗测试，结果表明，相较于定排量机油泵，变排量机油泵在各车速下均具有明显的油耗优势，但随着车速增加优势逐渐减小。中国循环油耗测试中，在城市段变排量机油泵具有明显的油耗优势，而在城郊和高速段优势相对减小。综上所述，通过变排量机油泵精细化控制机油压力，可显著提升发动机燃油经济性，低负载和城市驾驶条件下节油效果尤为显著。

Traditional fixed displacement oil pumps often have higher pumping capacity than the actual demand in most engine operating conditions, leading to additional energy losses. A variable displacement oil pump can dynamically adjust the effective displacement to reduce pump drive power and improve fuel savings. The experiment was conducted on a 2.5 L diesel engine to test the fuel saving potential of a variable displacement oil pump. Prior to the experiment, the oil pressure demand from various components was calculated, and the control characteristics of the variable displacement oil pump were evaluated. Based on the data, optimal oil pressure control targets were established. The comparative tests between the variable displacement oil pump and simulated fixed displacement oil pump were then conducted on an engine performance test bench. The results indicated that the reverse drag torque of the variable displacement oil pump decreased and obtained a reduction of approximately 2.5 N·m particularly under urban driving conditions. Additionally, the overall fuel consumption of the engine reduced, with the lowest specific fuel consumption reduced by 4 g/(kW·h). The vehicle tests for constant speed fuel consumption and China Cycle fuel consumption were conducted on a chassis dynamometer. The results indicate that, compared to fixed displacement oil pumps, variable displacement oil pumps offer significant fuel economy benefits at all vehicle speeds, although this advantage diminishes with the increase of vehicle speed. Notably, during the China Cycle fuel consumption test, the variable displacement oil pump exhibits a clear fuel consumption advantage in the urban segment, while the benefit is less pronounced in the suburban and highway segments. In summary, the precise control of oil pressure regulation enabled by the variable displacement oil pump substantially enhances engine fuel economy, with particularly notable fuel improvements under low-load and urban driving conditions.