宝马X5系列轿车中的V8汽油发动机多功能护盖有着很高的技术含量

宝马X5系列轿车的动力系统采用了豪华轿车的配置。在动力方面，采用了在宝马5系列和7系列轿车中已经使用的V8 4.8L发动机，可满足欧Ⅳ和美国ULEVⅡ的尾气排放标准。在原来设计车型中副变速器中用于转换曲轴旋转运动的变速器，已经被采埃孚公司生产的6挡变速器和四轮驱动的X-Drive所取代。

对于宝马X5系列轿车的动力，宝马公司使用了在宝马 5系列和7系列轿车中已经使用的V8 4.8L发动机，不同的是X5系列轿车的V8发动机的压缩比略小，从而满足了欧Ⅳ和美国ULEVⅡ的尾气排放标准。因此，该发动机的油耗标准也下降到了12.5L/100km。这一顶尖技术的发动机采用了Vanos进排气门变量控制凸轮轴、Valvetronic无级可调电子气门控制技术和两级控制的可变长度进气管。

Vanos和Valvetronic

Vanos进排气门变量控制凸轮轴和Valvetronic无级可调电子气门控制技术同样可以在普通的3L直列6缸汽油发动机中使用。它可以产生200kW的功率和315N/m的输出扭矩。它的最大特色是由铝合金和锰合金制造的轻合金材料的缸体。嵌铸的铝合金材料包裹着缸套，提供了足够的强度。在这种嵌铸的铝合金周围，宝马公司使用了锰合金材料，铸成了整个缸体。这种缸体结构比全部采用铝合金材料制造的缸体重量还要轻24% ，比灰铸铁材料的缸体要轻43%。整个6缸缸体的重量只有161kg，比原来设计的同类型缸体的重量又减少了10kg。

为了进一步节约燃油，X5轿车的发动机配备了电子驱动的、能够按照工作需求驱动的冷却水泵，为冷却系统提供冷却水。与原来设计的发动机相比，这种X5轿车的新型发动机又可减少14%的高牌号燃油的燃油消耗量，同时又可将发动机的输出功率提高18%。惟一美中不足的是：由于宝马公司SUV的主要市场是美国，因此在X5 3.0i型轿车中必须放弃2007年款新型3系列轿车中所使用的直接喷射系统，因为在美国还没有直喷系统所需的无硫燃油。

更大的功率和输出扭矩

在发动机换型之后，X5系列轿车的6缸柴油发动机也可提供更大的功率和输出扭矩。发动机性能的改进首先取决于反应速度极快的新型可调节涡轮增压器。

更重要的是稀混合气点火向压电喷射的共轨喷射技术的转换。在压电喷射技术中，燃油喷射量更精确、快速，可以在高达160MPa的压力下将燃油喷射到6个气缸中，从而可以更加有效地利用能源，进一步降低发动机有害成分的排放。这种新型的燃油喷射方式可以将功率提高6%，但是柴油的消耗却增加不多（由原来的8.6L增加到了8.7L）。

在经过金属和陶瓷两级三元催化器之后，发动机排出的尾气中绝大部分是无害气体。Boysen公司将这两种带有镀铂层的催化器紧凑地安装在椭圆型的催化器壳中，在催化器和尾气颗粒过滤器之间的间距仅10mm，并且还有足够的空间用于安装温度传感器。与靠近发动机的三元催化器结合单独的颗粒过滤器尾气净化系统相比，Boysen公司的这种技术方案所占用的空间更少，重量更轻，成本更低。

为了达到所需的尾气净化效果，Boysen公司必须最合理地利用现有的可用空间。不仅进气歧管，而且排气歧管都必须非常扁平，同时在过滤器附近和排气歧管附近的管道进行了隔热处理。通常，温度敏感的零部件和发动机的尾气处理系统受到尾气颗粒过滤器的影响，而隔热板和隔热材料排除了这一现象的发生。

在消音器的设计中，Boysen公司的研发人员也考虑了3L发动机的重量和成本问题。他们研发的中置消音器也集成了后置消音器的功能。据Boysen公司介绍，中置消音器和排气歧管，以及靠近发动机的三元催化器等将在宝马公司美国斯巴达堡市生产厂中进行生产。

阿文美驰公司与宝马公司共同研发了宝马X5系列轿车的排气系统

整体方案

X5系列轿车排气系统的整体方案是由宝马公司与阿文美驰公司共同研发的。由于采用了贴近发动机配置的V8发动机排气歧管、三元催化器和带有空气隔离的进气歧管等措施，有害物质排放显著较少，背压明显降低的良好效果。其紧凑的和模块式的结构设计也降低了零部件的生产成本。同样，阿文美驰公司也为X5轿车V8发动机生产最后一级的消音器。所有的单通道和双通道配置方案以及排气系统的内部构件都可以在1套生产设备上生产。

6挡变速器

在原来设计车型中副变速器中用于转换曲轴旋转运动的变速器，已经被采埃孚公司生产的6挡变速器和四轮驱动的X-Drive所取代。与原来的配置方案比较，新的液压控制系统可以将离合反应时间缩短高达50%。另外，这种变速器可以快速地跳过1个或几个变速挡直接进入更高的或更低的变速挡中。

这种6挡变速器还有一种电子选挡控制开关，而这一电子挡位控制开关并不位于方向盘上，相反是按照传统的配置方式安装在正副驾驶员之间的中控台处。经变速器传递出去的驱动力矩按照40：60的比例分配给前后轮。

在交替变化的行驶状态中，或者在负载较低的情况下，分动器在电子控制的片式离合器的作用下将动力动态地分配给车轴。在极端的条件下，X-Drive控制系统会将全部牵引力输送给前轴或者后轴，明显地提高了汽车的动力性能。

Drive Alliance for BMW X5Dynamic and efficient V8 performance

It goes without saying that a premium segment SAV requires and deserves a choice of powerplants which provide impressive torque and power combined with outstanding running refinement. For the U.S. there will be two models, one six cylinder and one V8.

The V8 in the BMW X5 4.8i offers a high level of performance at all times. Upgraded and renewed in virtually every respect, this top-of-the-line engine develops a maximum output of 350 hp from an engine capacity of 4,799 cubic centimeters. In addition to double-VANOS variable camshaft adjustment and VALVETRONIC fully variable valve drive, the V8 now comes with even more sophisticated and efficient engine management.

The V8 in the new BMW X5 4.8i develops maximum torque of 350 lb-ft from 3,400 to 3,800 rpm, offering efficient dynamics of the highest standard. Accelerating from a standstill to 60 mph in 6.4 seconds, this top-end model will not disappoint the true driving enthusiast.

Last but not least, the new V8 in the BMW X5 4.8i fulfils the exhaust emission regulations of both the Euro 4 standard and the ULEV II classification in the US.

Responsive and light: the magnesium/aluminum inline six

The inline-six in the new BMW X5 3.0si likewise reflects the latest state of the art in engine design. This 3.0-liter engine combines smooth, linear response with superior refinement and harmony. Maximum output is 260 hp, peak torque of 225 lb-ft comes at 2,750 rpm. The BMW X5 3.0si accelerates to 60 mph in 7.8 seconds.

Double-VANOS and VALVETRONIC also help to give this engine optimum output and efficiency. Engine weight has been reduced at the same time thanks to the magnesium/ aluminum crankcase. It reduces the overall weight of the new six-cylinder by 22 lbs to just 355 lbs – an advantage which helps to achieve near-perfect weight balance and reduce vehicle weight.

The water pump in the cooling system now operates electrically only on demand which also makes an additional contribution to all-round economy.

New six-speed steptronic automatic transmission with even faster shifting and enhanced shift comfort

The new BMW X5 comes standard with a six-speed STEPTRONIC automatic transmission enhanced to an even higher level than before. The new six-speed automatic shifts with unparalleled speed, for outstanding precision and efficiency. It provides not only driving comfort but, above all, the dynamic performance expected of a BMW X5. And the transmission helps the engine to achieve a high standard of all-round fuel economy.

The new automatic transmission comes in two versions tailored specifically to the torque of the six-cylinder engine, on the one hand and the V8, on the other. Both versions feature new converter technology and particularly efficient, high-performance software which reduces reaction and shift times versus a conventional automatic transmission by up to 50 percent. And direct detection of the target gear required allows the driver to skip one or even several gears when shifting down, without taking any additional time.

With its unusually dynamic gearshift and extremely direct connection to the engine, the new six-speed STEPTRONIC automatic transmission is a rewarding partner for either engine. And at the same time it helps to ensure smooth, relaxed and fuel-efficient cruising at low engine speeds.

New electronic gear selector

The automatic transmission is controlled by a new electronic gear selector featured for the first time on the new BMW X5. The new electronic gearshift selector lever moves back to its starting position after each use.

Transmission management is now no longer mechanical, but is effected through electrical signals. The parking position, for example, is activated by pressing the P button on the upper side of the selector lever. Then, to select a drive gear manually, all the driver has to do is press the selector lever to the left and is now able to shift gears sequentially by hand. To shift up, pull the selector lever back and to shift down, push the selector lever forwards. A display in the selector lever itself and in the instrument cluster shows which gear is currently engaged.

Apart from short and ergonomically convenient gearshift travel ensuring a high standard of comfortable use, the new gearshift lever offers the further advantage of providing enough space on the center console for additional storage areas and two generous cupholders.

两套电子控制的轿车发动机控制系统：新的变速器和i-Drive监控装置