#Cadillac & the 2-mode #Hybrid: #Green #Luxury

The Cadillac Escalade uses a 6L V8 engine with a 2-mode Hybrid power train.  With Cadillac thinking of releasing a 2-mode hybrid + 3.6L DI V6 in the upcoming XTS Platinum, let’s review how the 2-mode Hybrid system works.

2010 Cadillac Escalade Hybrid

Operation:  In a 2-mode hybrid, compact and powerful electric motors are integrated into the transmission and work with traditional transmission gears and electronic controls to provide two modes or ranges of infinitely variable gear ratios. The input split mode is used for launching the vehicle from a stop, driving at low speeds and providing superior performance and moderate load trailer towing. The compound split mode is used primarily when the vehicle is at higher speeds to provide efficient cruising.

The drive modes alternate seamlessly between the input split mode and a compound split mode. In the input split mode the vehicle can operate on electric, mechanical or a combination of the two. The vehicle operates as a full hybrid when the engine is shut off at low speed and light loads, as leaving the engine off for extended periods of time and moving under electric power is key to reducing fuel consumption in stop and go traffic.

So, in other words, the vehicle can operate in electric-only mode at low speeds, or with light loads, or gasoline only mode for cruising, often with cylinder deactivation and other complementary technologies.  The hybrid powerplant uses regenerative braking and other techniques to recharge on the go.  A plug-in 2-mode hybrid can also recharge using standard wall current when available.

Under the hood shot of hybrid powerpack

A key contributor to the Escalade Hybrid’s fuel economy is the gasoline engine’s Auto Stop mode. Once the vehicle reaches 0 mph, the gasoline engine is automatically shut down. By leaving the engine off and allowing the vehicle to move only under electric power, such as during heavy stop-and-go traffic, fuel consumption is greatly reduced.

However, when extra power is required, such as for wide-open-throttle acceleration from a standing stop, the Vortec 6.0L V-8 is seamlessly restarted so it can deliver the necessary power and torque. In this case, the engine is restarted effortlessly from the Auto Stop mode using the EVT’s powerful internal electric motors; there is no traditional starter motor.

A 2-mode hybrid has a smaller powerpack than an extended range electric vehicle such as the upcoming Chevrolet Volt or Cadillac Converj.  Press conjecture is that the Hybrid XTS concept may have enough powerplant to drive for 10 miles between recharges; the Volt or Converj should be able to go 40 miles between charges.  My daily commute of around 1 mile would be gas-free with a 2-mode hybrid XTS.

The mild-hybrid system in the Chevrolet Malibu offers a 4 mpg improvement over the non-hybrid Malibu.  So although Cadillac has not released any projections, the Cadillac XTS perhaps will get over 30 mpg on the highway EPA cycle — quite an achievement for a fullsize performance luxury sedan.

A plug-in hybrid-electric vehicle differs from non-plug-in hybrid-electric vehicles by offering extended electric-only propulsion, additional battery capacity and the ability to be recharged from an external electrical outlet.

When ready for production, the Lithium Ion energy storage system will be replenished when the battery charge is depleted to a specified level by utilizing the 2-mode hybrid system’s electric motors and regenerative braking systems. When the vehicle is parked, the battery can be recharged using a common household exterior 110-volt plug-in outlet.

2010 Cadillac XTS Platinum Concept with Plug-in Hybrid and DI 3.6L V6

The 2-mode hybrid system will be altered for use with plug-in technology. It maintains two driving modes — one for city driving, the other for highway driving. In addition, special controls will be utilized to enable higher speeds during electric-only propulsion and maintain electric- only propulsion for longer periods of time.

GM has also stated the desire to produce a 2-mode hybrid or extended range electric version of the SRX.