The first application of Cummins Valvetrain Technologies’ engine brake will be on Cummins’ X10TM engine for medium-duty vehicles, serving vocational and regional transit bus fleet customers.
The X10 engine is part of Cummins’ fuel-agnostic engine lineup, replacing both the L9 and X12 engines. Cummins’ Stroke HPD engine brake, designed for the X10, offers small and medium displacement engines the retarding power typically found in larger engines. It generates up to 40 per cent higher levels of supplemental braking force than traditional compression release braking at high engine speeds, and improvements of up to 100 per cent at lower RPM cruising speeds. This advancement supports the commercial vehicle industry’s pursuit of better fuel economy and a lower total cost of ownership.
A conventional internal combustion engine has one compression release (CR) and one brake gas recirculation (BGR) event for each engine rotation. With 1.5-Stroke HPD, cylinder deactivation (CDA) mechanisms are used to manage the engine’s main exhaust valve events, allowing for two CR events per cam rotation.
A standard intake charge event is used to power the first CR event; however, for the second CR event, the power is achieved through the recirculation of exhaust manifold gases, without drawing air from the intake.
Two HPD engine brakes, a 3-cylinder and 6-cylinder version, will be offered on the X10 to provide coverage for customers formerly specifying Cummins L9 (medium-duty) and X12 (heavy-duty) engines, respectively. The advanced brake offers up to 320 hp at 2300 rpm for the 3-cylinder option, and up to 475 hp at 2300 rpm for the 6-cylinder option.
RaNae Isaak, Programme Leader of the X10 at Cummins, said: ‘The ‘PD engine brake’ is a unique and ideal braking solution for the wide displacement coverage of the new X10 engine, accommodating various duty cycles. Feedback from both OEM and end-user customers who have test-driven the new X10 with the HPD engine brake highlights its capability to deliver braking power comparable to that of a 13-litre truck, despite using a 10-litre displacement engine. Many users have commented that the HPD engine brake provides the most powerful braking solution they have ever experienced in a vehicle.
‘HPD is part of Cummins Valvetrain Technologies’ modular design framework, allowing for the integration of other valvetrain technologies according to local market requirements. It is currently being developed in six other engine programmes.
Punching above its weight class, the HPD engine brake presents an attractive and differentiating proposition for both engine and vehicle designers. It is a perfect match for the Cummins X10 engine due to its diverse applications that require high braking performance. With the exhaust side of Cummins’ Cylinder Deactivation (CDA) already integrated into the HPD, future applications will allow Cummins to build engines tailored to specifications for full CDA in customer markets that demand fuel-saving and emissions-reducing technologies. To achieve this, only additional control solenoids and collapsing intake mechanisms need to be added to an already protected framework.
