|The hybrid powertrain in the Volvo L220F Hybrid. Click to enlarge.
Volvo Construction Equipment (Volvo CE) unveiled a pre-production prototype of its L220F Hybrid wheel loader at the CONEXPO-CON/AGG exhibition, 11-15 March 2008 in Las Vegas. The L220F Hybrid offers more power, better performance and a 10% reduction in fuel consumption, according to Volvo.
Leveraging its position as the world’s largest manufacturer of heavy-duty diesel engines in the 9 to 18-liter class, the Volvo L220F Hybrid’s parallel mild-hybrid technology has been developed within the Volvo Group and uses the D12 engine as its platform.
|The L220F Hybrid.
While much of the technology remains confidential, subject to patents pending, the heart of the hybrid system is an ISG—Integrated Starter Generator. Fitted between the engine and the transmission, the ISG is coupled to an advanced battery.
Up to 40% of a wheel loader’s time can be spent with the engine idling. The ISG allows the diesel engine to be turned off when stationary and then almost instantly restarted by rapidly spinning the engine up to optimum working speed using the high power battery.
The ISG can also overcome the problem of low torque at low engine speeds by automatically offering a massive electric torque boost—the ISG’s 50 kW electric motor offers torque of up to 700 Nm (516 lb-ft) from standstill.
The combination of these two attributes of the ISG mean that the diesel engine will remain off for long periods when it would otherwise be idling and that the operator does not need to over-rev the engine in order to get sufficient torque to work, as peak torque will be offered at almost tick-over engine speeds. The battery is then replenished automatically without reducing productivity, with the ISG acting as a dynamo/alternator.
While the ISG is the heart of the system, there are other energy saving innovations in the L220F Hybrid, such an electrically powered climate control system (rather than being powered directly by the engine).
The Volvo L220F Hybrid will be Volvo’s—and probably the industry’s—first commercially available wheel loader when deliveries begin in late 2009.
In late 2007, Volvo Technology Transfer AB became a part-owner in El-forest AB, based in Örnsköldsvik, Sweden, and is thereby investing in the development of energy efficient and environmentally sound forestry machinery. The El-forest forwarder is the world’s first forestry machine that uses hybrid-electric technology. The hybrid forwarder uses a series hybrid architecture, with the genset powered by a small diesel. The forwarder is moved by 23 kW traction motors in each wheel. Fuel consumption can be cut by up to 50% compared to conventional forwarders. (Earlier post.)