2017年美国工程机械展（Conexpo2017）上，英国工程机械与农业设备制造专业公司JCB表示，公司的入门级产品3.0L DieselMax柴油发动机将在2017年晚些时候搭载在一款工程机械上进入美国市场。

JCB公司发动机部主管AlanTolley表示，这款DieselMax柴油发动机可以按照行业标准输出74-hp (55-kW)功率并同时满足美国EPA的Tier 4排放标准，整个工作过程无需采用SCR选择性催化还原系统，可以有效降低设备的运营成本和维护保养难度。

此前，JCB公司的4.4LEcoMax柴油发动机是公司排量最小的四阶段（Tier 4）发动机，而Dieselmax 4缸柴油发动机的尺寸比EcoMax还小25%。在展会期间的采访中，Tolley告诉《卡车与非公路工程》杂志（Truck & Off-Highway Engineering），这款新型3L发动机的重量也比4.4L发动机大约轻30%，燃料经济性也要高8%左右。此外，尽管DieselMax的尺寸比EcoMax发动机小很多，但一样可以输出295 lb·ft (400 N·m)的扭矩。

“我们在这款发动机的设计中认真考虑了一些重型设备的需求。”Tolley向记者介绍了这款发动机在耐用性和维护保养方面的设计优势。DieselMax的换油间隔可以延长至1,000小时，具体可配合燃料过滤器的更换周期；而发动机采用的液压挺杆设计也意味着用户无需周期性的进行阀门调节。此外，发动机还配备了一个电控涡轮增压废气门和多个预热塞，可协助发动机快速达到理想工作温度，确保流畅、安静的运行性能。

“DieselMax的燃耗更低、工作噪声更小且保养间隔更长，能够真正造福终端用户。”Tolley表示，DieselMax发动机非常适合各类铲斗机、装载机、挖掘机等建筑设备。

高科技的“甜点”

Tolley表示，受到最新美国和欧洲排放要求的限制，目前市面上的发动机大多以最大功率55 kW的产品为主。

“55-kW发动机开始变得很受欢迎，”Tolley表示，“然而，你必须采用SCR系梳才能满足美国的Tier 4或欧洲的Stage IIIB规定。”Tolley表示，一些地区和公司对SCR型发动机的态度有所退缩。他表示，不同地区对SCR系统的接受程度有所不同。此外，设备类型及工作占空比需求不同也会影响大家对这种系统的容忍度。比如，一些设备租赁公司就很反对氧化还原剂的使用，因为这会增加公司的维护成本。

此外，DieselMax还同时采用了冷却废气循环（EGR）和共轨加油系统，能够满足设备的启停需求。Tolley表示，DieselMax发动机还可升级采用一款可变几何形状涡轮增压器，但这对于这款发动机55 kW的输出功率并没有必要。Tolley表示，这款发动机还可以通过调整输出更高功率，但这样一来就必须借助加载SCR设备才能满足相关规定，因此单纯升级涡轮增压器并没有太大意义。

Tolley补充说，DieselMax完全可以为绝大多数目标设备提供足够的功率。目前，这款发动机可以在1,200-1,250转时取得最大功率，几乎在完整操作区间内均能实现峰值扭矩。

按照计划，新款DieselMax将由JCB公司位于英国的Darby装配厂负责生产。

Off-highway powertrain and driveline specialist JCB said at Conexpo 2017 the company is starting production of its new entry-level engine, the 3.0-L DieselMax, with its first applications in OEM machines coming in the U.S. market later in 2017.

Alan Tolley, group director—engines at JCB Power Systems, said DieselMax’s key design feature is that it produces the industry-standard 74-hp (55-kW) rating while complying with U.S. EPA Tier 4 emissions standards without selective catalytic reduction (SCR) exhaust aftertreatment, a boon for reducing operating cost and maintenance complexity.

The Dieselmax 4-cylinder also is 25% smaller than JCB’s 4.4-L EcoMax diesel, until now the company’s smallest-displacement Tier 4-compliant engine. The new 3L also is roughly 30% lighter than the 4.4-L engine—and as much as 8% more fuel-efficient, Tolley told Truck & Off-Highway Engineering during an interview an Conexpo. And the DieselMax may be significantly smaller than the 4.4-L, but generates the same torque rating of 295 lb·ft (400 N·m).

“We’ve very much taken the (JCB) heavy-duty architecture into this design,” Tolley said in noting the new engine’s design priorities of durability and low service requirements. The oil-change interval can extend to 1000 hours, matching the fuel-filter change schedule and hydraulic tappets mean no periodic valve adjustments. There also is an electronically-controlled turbocharger wastegate and glowplugs for quickly achieving a temperature conducive to smooth operation, quiet operation.

“What the end user gets is less fuel consumption, low noise and longer service intervals,” Tolley said of the Dieselmax, which will be suitable for OEMs to specify for all manner of backhoes, loaders, excavators and other construction equipment.

High tech for the sweet spot

Tolley said engines with a maximum output of 55 kW now play a significant role in the market because of the latest emissions standards in the U.S. and Europe.

“55-kW is getting very popular,” he said. “Above that, you need SCR (for Tier 4 and Euro Stage IIIB emissions compliance).” He said there has been pushback in some regions or by some operators regarding engines that require SCR. There is a comfort level with SCR that varies by region, machine type and duty cycle, he said. Rental operations, for example, are averse to SCR because of maintenance concerns.

The DieselMax also has cooled EGR and common-rail fueling and is capable of accommodating stop-start operation. He said it would be possible to use a variable-geometry turbocharger, but it is not needed to achieve the 55 kW rating. Tolley said the engine could be tuned for more output, but since that would require fitment of SCR, there wouldn’t be much sense in using a more-sophisticated turbocharger.

He added that the engine’s operating characteristics provide more than enough power for most equipment that would use the engine. Maximum power is developed at 1200-1250 rpm and peak torque is available almost throughout the DieselMax’s operating range.

The new DieselMax is built by JCB at its assembly plant in Darby, United Kingdom.

Author: Bill Visnic
Source: SAE Truck & Off-highway Engineering Magazine