Hybrid Bus          

The GM Allison Hybrid Ep System features two-mode compound split parallel architecture with two paths - a pure mechanical path and a pure electrical path - to achieve the highest energy efficiency. Two electrical motors combined with a very efficient mechanical path and energy storage provide efficient stop-and-go application as well as effective highway performance. The entire system is controlled by comprehensive energy management software.

EMISSIONS REDUCED

With the GM Allison Hybrid E System, overall emissions are significantly reduced during operation compared to conventional combustion engines. Oxides of nitrogen (Nox) emissions are reduced up to 50% even with the latest 2.5 gram/hp-hr engines. The system also provides significant emission reduction when compared to alternative propulsion systems.

REGENERATIVE BRAKING

When stopping or decelerating, vehicle energy is converted to electric energy and stored. In effect, the motor becomes a generator. 40% of the energy to accelerate the bus comes from the energy saved during regenerative braking.

PROVEN DURABLITY

The advanced Nickel Metal Hydride energy storage system has a 6-year target life and no requirement for battery conditioning. In over 12 million in-service miles, the GM Allison Hybrid E System has not had a single battery cell failure. And , in summer thermal tests conducted in Death Valley, the system has not had any type of hybrid failure in all the years of testing (2002 through 2005).

ENHANCED ACCELERATION

A bus equipped with the GM Allison Hybrid E System can significantly out -accelerate a similar bus equipped with a conventional drivetrain or an alternative fuel system. And the acceleration is seamless.

IMPROVED FUEL ECONOMY

The National Renewable Energy Laboratory (NREL) conducted chassis dynamometer tests using two 60’ buses- one with the GM Allison Hybrid E System and one with a conventional powertrain. The testing showed a 75% improvement in fuel economy during a stop-and-go Manhattan duty cycle. Actual in-service fuel economy improvements range from 20-54% compared to conventional buses.

                    QUIET OPERATION

The GM Allison Hybrid E System helps reduce noise pollution compared to conventional buses. At 79 db@10 meters, buses equipped with the system approach the sound level of passenger cars.

At a standing start, acceleration is more efficiently achieved through the electric motors. As road speed increases, the electric power is blended with mechanical power. Higher road speeds are achieved through pure mechanical power.

THE SECRET IS ITS SIMPLICITY

The GM Allison Hybrid Ep System is a study in the marvels of simplicity. The system consists of just six components - Ev Drive, Dual Power Inverter Module (DPIM), Energy Storage Unit, System Controllers and Range Selector. System components are designed to fit in virtually the same space claim as a conventional drivetrain. This compact package easily install in low- and high – floor bus chassis.

DUAL POWER INVERTER MODULE (DPIM)

The DPIM’s purpose is to convert electrical energy into alternating current (AC) or direct current (DC). The Ev Drive motor/generators use and produce AC, while the Energy Storage unit can only share DC. The DPIM acts as a sort of “middleman” that converts electrical energy for easy transfer, storage and use.

ENERGY STORAGE UNIT

The Energy Storage unit supplies electrical energy to the Ev Drive’s electrical motor/generators. Energy Storage units vary in design and size per vehicle type and vocation. Stored electrical energy is created during normal motor/generator operation and during regenerative braking. Energy Storage lessens the demands on the clean diesel, thereby reducing emissions, fuel consumption and noise.

SYSTEM CONTROLLERS                      

Two System Controllers (Hybrid Control Modules) act like the “brain” of the GM Allison Hybrid E System. They process information from system components and driver inputs. The System Controllers provide system command and control for precise vehicle propulsion and energy production. They also perform diagnostic and reprogramming functions.

RANGE SELECTOR

The GM Allison Hybrid E System range selector is identical to the electronically controlled Allison Automatic range selectors. The driver simply pushes D for forward or R for reverse.

                              Ev DRIVE

The Ev Drive appears similar to the Allison Transmission’s Bus Series automatic transmission models and is equipped with the following components:

• Planetary gears and clutches
• Electronic solenoids and valves
• Two motors/generators

All components work together to create two continuously variable operating ranges. The electric motor/generators act as variable clutches to accelerate, slow or hold planetary components.

The Ev Drive is a true infinitely variable transmission with an infinite number of gear ranges. It is a vehicle designer’s dream come true.