Liberty cockpit via Johnson Controls

At $1.7 billion, the 2002 Jeep Liberty four-door program went from concept to volume launch in 29 months.

Automakers are expected to outsource more than 80% of vehicle cockpits in North America by 2008, doubling the amount of supplier contributions in 1996, according to some industry experts. Marking its first time for engineering and integrating a complete cockpit module, Johnson Controls Inc. is the "inside face" of the all-new 2002 Jeep Liberty, the successor to the Jeep Cherokee.

The SUV's cockpit, defined in this case as the instrument panel module assembly and several subsystems, involved 35 suppliers, including Dow Automotive, Akzo Nobel, Hella, Valeo, TRW, Alpine, Lear, Alps, Lucas Body Systems, and Siemens. The 53-kg (117-lb) cockpit is composed of instrument panel trim, cluster, junction block (fuse panel), steering column, structural duct, pedal system, instrument panel wire harness, body wire harness, airbag system, HVAC system, and audio system. A mass reduction of 10% was achieved as compared to the same systems in the Jeep Cherokee.

Johnson Controls is the systems integrator for the Jeep Liberty cockpit.

"This is DaimlerChrysler's most exported vehicle," said Jeffrey Gras, Chief Engineer-Interiors for Johnson Controls Inc. Automotive Systems Group in Holland, MI. Both left- and right-hand 2.4- and 3.7-L gasoline, as well as the 2.5-L diesel, versions of the Liberty are expected to be sold in more than 90 countries. Seventy percent of the cockpit parts are common to left- and right-hand drive versions. Of the remaining 30%, 60% of the components are symmetrically opposite.

A molded-in glove box hinge and a molded-in wire channel represent unique attributes on the 406-mm (16-in) wide polycarbonate/ABS material, vibration-welded instrument panel. "The Liberty is the first structural IP system to carry full cockpit content," Gras said. "An advancement we made in cockpit architecture is a three-piece injection-molded cross-car beam. This eliminates the need for steel or magnesium structures. The structural duct becomes the reaction surface during a crash situation. No second surface steel is required. The duct also carries the weight of the cockpit, including the steering column, HVAC system, and airbag module."

A worker completes a task during assembly of the cockpit for the Jeep Liberty.

From receipt of order at the Johnson Controls Northwood, OH, manufacturing facility to installation at the Daimler-Chrysler Toledo North Assembly Plant, the process unfolds in a 204-min timetable. "There is no pre-assembly done in anticipation of the order," said Bruce MacLachlan, Plant Manager-Interiors for Johnson Controls. Cockpits are built, tested, loaded, and delivered on a just-in-time basis to the Jeep Liberty plant, the newest assembly plant in the DaimlerChrysler portfolio.

Johnson Controls also supplies Jeep Liberty front and rear seats, reading lamps, rear cargo lamps, and an overhead console that features a trip computer, temperature gauge, PathPoint digital compass, and HomeLink Universal Transceiver.

- Kami Buchholz

Eaton adds variability to Displacement on Demand

Eaton's variable-valve actuation for GM's Displacement on Demand included research in a rocker-arm-based cylinder deactivation concept,

Eaton Corp. has received a $500 million contract from General Motors to provide variable-valve-actuation (VVA) technology and components for the OEM's new advanced powertrain technology called Displacement on Demand. It is being developed for use on GM's Generation IV V8 engine, which will be introduced in 2004 on the company's trucks and SUVs.

Eaton will supply deactivating lifters for the Displacement-on-Demand system, enabling the engine to run on only four cylinders during cruise conditions, improving fuel economy. In addition to this device, Eaton will provide GM with the hydraulic actuation mechanism from its Actuator and Sensors Division.

...pushrod and overhead valvetrain deactivation,

VVA technology is based on the lifter, which is a hydraulic lash adjustment device riding on a roller. Typically, the roller rides on the cam and pushes up the pushrod, which works on the rocker arm and activates the valve. "We have incorporated a hydraulically actuated lashing device that either lashes the inner of the lifter to the outer body or detaches the body from the internals of the lifter, thereby not translating the motion from the cam onto the pushrod," said Nandu Srinivasan, Manager of Advanced Engineering for Engine Air Management Operations at Eaton Corp. "When it gets hydraulic pressure on the lash pin, it detaches the body. It is not locked together and it basically rides up and down on the cam lobe like a telescope as opposed to pushing the rod up."

This system differs from the one pioneered on a Cadillac V8 engine in 1981 in that the detachment of the cam profile and cam input from the valve on the Cadillac occurred at the fulcrum of the rocker arm. Also, the mechanism on the Cadillac was a rotational solenoid.

...a variable-ratio rocker system for lift/timing control,

According to Srinivasan, although the device operated properly, Cadillac discontinued its use because the change from eight- to four-cylinder operation was very noticeable to drivers. "The system was a little bit before its time," said Srinivasan. "Electronics technology had not come as far as it has today. Things such as the ECU, ECM, controllers, memory capacity, and algorithm development were not quite there yet." Another contributor to the system's difficulties was that electronic-throttle-control technology was also not available.

Operation of today's GM system is quite imperceptible, said Srinivasan. The actuation is hydraulic and occurs within one cam revolution after the ECM sends the actuation command. This all occurs in about 120 ms at 1000 rpm or 40 ms at 3000 rpm.

In developing its VVA technology for Displacement on Demand, system serviceability was also taken into account. The actuation system is actually placed in the "V" of the engine for accessibility. Half the cylinders contain normal lifters while the other half have deactivating lifters. However, the dimensional envelopes of the lifters are very close, enabling them to fit within the same bore. In addition, the devices will be supplied in modules within a plastic container that prevents rotation. This essentially makes the system a plug-and-play device.

...and a rocker-arm-based dual-lift system concept.

The VVA technology has already been demonstrated on test-drives from Detroit to the eastern U.S. About 8.5-9.4 km/L (20-22 mpg) was achieved in a full-size truck—a 10-15% fuel economy benefit.

Eaton is also developing variable-lift and -timing devices with several other global customers. These will be either rocker-arm- or lash-adjuster-based.

"We are also working on variable-ratio rocker systems that allow the rocker arm geometry to be changed on the fly," said Srinivasan. "Instantaneously changing the geometry enables the engine to achieve variable lift and timing simultaneously. At the concept level, we are currently developing a totally variable mechanical-valve-actuation system that uses a cam, but has more sophisticated and complex geometry changes that allow for timing, lift, and duration flexibility." The company is currently introducing this concept to its customers.

"We are also in the concept development stage of a camless actuation device that will be packaged with a cylinder head module that includes valvetrain components," said Srinivasan. The entire actuation mechanism will be housed within either the cylinder head or a portion of the head.

- Frank Bokulich