Peugeot's 2011 diesel hybrid pioneers GKN electric drive, clutch technology

  • 26-Aug-2010 12:43 EDT

Side view of GKN Driveline's gearbox for the Peugeot 3008 HYbrid4 shows the electric connectors for the disconnect actuation and position status. GKN Driveline's Bruneck, Italy, facility will assemble the entire electric rear drive module.

A 2011 model year Peugeot crossover vehicle debuts the automaker's HYbrid4 technology that uses a two-stage gearbox with integrated differential and an electromagnetic disconnect clutch from GKN Driveline.

The Peugeot 3008 HYbrid4 is expected to be the first diesel hybrid passenger vehicle to enter production. It was designed to give all-wheel-drive capability to the previously front-drive-only 3008, with the benefit of ultralow emissions. Its 99 to 109 g/km CO2 output (the difference is due to tire options) is the same as that of Peugeot's tiny 107 city car.

The 3008 HYbrid4 features a "through-the-road" type parallel-hybrid architecture. A 2.0-L HDi diesel engine, fitted with an 8-kW high-voltage stop-start system and connected to a 6-speed automated manual gearbox, drives the front wheels. The diesel is rated at 164 hp (121 kW) and 221 lb·ft (300 N·m).

Providing supplemental drive torque to the rear wheels is GKN's electric-drive module capable of producing 36 hp (27 kW) and 147 lb·ft (200 N·m). The car's front IC and rear electric power modules are not connected mechanically. Four driver-selected modes enable the IC engine and electric drive to operate independently or in unison (as a parallel hybrid), providing FWD, AWD, or all-electric RWD and offering a total 200 hp and 368 lb·ft (148 kW and 500 N·m, respectively).

All-electric drive to the rear wheels is available up to 30 mph (48 km/h), with a range of approximately 2.5 mi (4 km) per charge.  

Through-the-road hybrid designs potentially suffer from rear axle parasitic drag when the vehicle is operating in front drive only. GKN Driveline developed its electromagnetic disconnect technology to eliminate the rear-axle drag in the Peugeot application, explained Robert Genway-Haden, the company's Product Technology Director-Americas.

The HYbrid4's changeover from diesel engine power to the Bosch-supplied permanent magnet synchronous drive motor is handled automatically by the stop-start system. Its alternator-starter puts the IC engine on standby and then restarts it when needed.

"Between FWD mode and electric-only mode, the HYbrid4's powertrain management unit utilizes the electric axle for parallel hybrid operation, providing additional torque on acceleration and recapturing energy on deceleration to convert the vehicle's kinetic energy into electrical energy for recharging the NiMH batteries," said Genway-Haden.

The rear drive module's disconnect apparatus is based on dog-clutch technology evolved from GKN Driveline's portfolio of electronic-locking differential products, like the devices used in the current Jeep Wrangler Rubicon and the Ford F-150.

"Although an initial burst of power is required to engage the clutch, a much lower current is required to keep it engaged, and that's an important factor in electric drive-only mode when running on batteries," noted Genway-Haden.

An upper limit of 74.5 mph (120 km/h) is needed to remain engaged or to reconnect on deceleration from higher road speeds. According to Genway-Haden, this threshold is the maximum permitted by the electric motor's operating rpm and the fixed gearbox ratio.

"The HYbrid4 control system can synchronize the electric motor to road speed and then seamlessly engage the electric drive when required," he added. "Reconnection occurs in less than 500 milliseconds."

GKN Driveline engineers worked through issues related to the engagement status of the disconnect dog clutch.

"Hall-effect sensors are typically used in position sensing, but unfortunately those sensors are susceptible to the magnetic field produced by the actuation coil," Genway-Haden explained. "The solution involved a combination of magnetic field modeling and iterative experimentation to develop the sensor layout, coil characteristics, and how the current is applied to yield reliable status detection."

The disconnect actuator in the 3008 HYbrid4 application is an adaptation of GKN Driveline's electromagnetically controlled AWD coupling.

"Our first application in 2002 was a pure launch assist system that disconnects at comparatively low speeds," Genway-Haden said of the system still being used on select Mazda and Nissan vehicles. That system has an electric motor rating of 3 to 5 kW, a high ratio reduction, and a wet-plate clutch disconnect.

Compared with the earlier application, the HYbrid4 disconnect technology has a higher power rating of 27 kW and a lower reduction ratio to facilitate higher speed operation. It is these features that give the new Peugeot its high fuel efficiency, FWD/AWD and electric-only drive modes, and enhanced vehicle dynamics.

Production of the 3008 HYbrid4 begins in early 2011, according to Martin Alloiteau, director of Peugeot marketing and communication. The France-assembled vehicle will be sold in European markets.

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