Bosch, PSA developing alternative powertrain concept
Following the successful introduction of the Bosch electric axle-split hybrid in PSA Peugeot Citroën diesel vehicles, Bosch and PSA Peugeot Citroën are planning to jointly develop a hydraulic hybrid powertrain for passenger cars.
The hydraulic system basically comprises two hydraulic units and their pressure accumulators. The power-split concept allows the vehicle to be driven in three ways: the conventional mechanical way, hydraulically, or by a combination of the two. At low loads, therefore, the internal combustion engine can be run at a more economical operating status.
When braking, moreover, the kinetic energy that would otherwise be lost as heat is converted into hydraulic energy and stored in a pressure accumulator. This energy can then be used to drive the car. In addition, driving off can be done purely hydraulically, and short distances driven without any emissions. The result is a potential average CO2 reduction of 30 percent in the new European driving cycle, and as much as 45 percent in a purely urban driving cycle.
Cost-effective hybrid powertrain for compact cars
In principle, this technology can be combined with any conventional engine. In an initial phase, it is to be used in the compact car segment, but it is also suitable for other passenger-car segments and light delivery trucks in urban traffic. According to the companies, this hydraulic-mechanical powertrain system results in a hybrid powertrain that is more cost-effective, robust, and service friendly. In addition, it does not require any special infrastructure, and can be deployed anywhere in the world.
The technology works on the same hydraulic powertrain principles as those used worldwide on a wide scale by the Bosch Rexroth. Bosch and PSA see great potential for adapting this technology to passenger cars. The collaboration between PSA Peugeot Citroën and Bosch dates back to an engineering alliance set up in 2008. In the context of this strategic partnership, Peugeot launched the 3008 HYbrid4 in 2011, the world’s first series-produced diesel hybrid passenger car with an axle-split powertrain.
In close collaboration with Bosch, PSA Peugoet Citroën developed the electrical components (electric motor, power electronics, and high-voltage generator) as well as the special technical design of the ESP® electronic stability program required for hybrid vehicles. This powertrain concept now also features in PSA’s Peugeot 508 (both the RXH station wagon and the HYbrid4 sedan) and Citroen DS5 HYbrid4 models. For these models as well, Bosch supplies the components for the electrical powertrain.
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