Methanol direct-injection achieves direct injection of diesel and methanol in the cylinder by using two independent fuel injection systems. This yields an extremely high methanol substitution rate and extremely low pollutant emissions. Due to these advantages, three injection strategies are proposed to investigate this injection method: D/M mode and M/D mode are where methanol injection occurs later and earlier than diesel injection respectively while M/D/M mode is where methanol is injected once before and once after the diesel injection. In this paper, these strategies are investigated, and the optimal settings of each are obtained and compared at low load and high load. The results show that in D/M mode, fuel economy is optimized and knock intensity increases with advancement of fuel injection and decreased injection dwell. This mode also effectively prevents knock but is not conducive to fuel economy. The most suitable methanol injection timings are obtained in M/D mode, namely 20°CA before the top dead center (BTDC) at low load and 30°CA BTDC at high load. Moreover, at low load the higher the first methanol injection ratio is, the better the fuel economy becomes, while at high load continued increases in the first ratio are limited by knock. Ultimately, M/D/M mode is found to be the best injection strategy at low load and high load.

甲醇直接喷射通过使用两个独立的燃料喷射系统实现了气缸中柴油和甲醇的直接喷射。这产生了极高的甲醇替代率和极低的污染物排放。由于这些优点，提出了三种喷射策略来研究这种喷射方法：D / M模式和M / D模式是甲醇喷射分别比柴油喷射晚和提前的情况，而M / D / M模式是甲醇喷射一次的机理。柴油喷射之前和之后。在本文中，对这些策略进行了研究，并获得了每种策略的最佳设置，并在低负载和高负载下进行了比较。结果表明，在D / M模式下，燃油经济性得到优化，并且爆震强度随着燃油喷射的推进和喷射停留时间的减少而增加。该模式还可以有效地防止爆震，但不利于燃油经济性。最合适的甲醇喷射时间是在M / D模式下获得的，即在低负载下上死点（BTDC）之前20°CA，在高负载下30°CA BTDC。而且，在低负荷下，第一甲醇喷射比越高，燃料经济性越好，而在高负荷下，第一比率的持续增加受到爆震的限制。最终，发现M / D / M模式是在低负载和高负载下的最佳喷射策略。在高负载下，第一比率的持续增加受到爆震的限制。最终，发现M / D / M模式是在低负载和高负载下的最佳喷射策略。在高负载下，第一比率的持续增加受到爆震的限制。最终，发现M / D / M模式是在低负载和高负载下的最佳喷射策略。