Rising gas prices have generated a wave of public interest and publicity about gas-saving hybrid electric vehicles (HEVs), and for good reason: Hybrids make good sense. Hybrid vehicles use “two or more energy conversion technologies.”
Often, an internal combustion or “heat” engine (ICE) using gasoline or diesel fuel develops primary power for traction and driving the on-board generator. Other fuels used include natural gas, propane, ethanol, methanol and dimethyl ether, and other engine types include natural gas and propane powered micro turbines, and hydrogen fuel cells. Hybrid EVs also use a source of stored secondary backup power, such as advanced batteries, ultracapacitors, or even flywheels, to augment the primary power source. Under prescribed driving conditions, the secondary source will assist or even take over propulsion of the vehicle. In some hybrid designs, secondary power is used exclusively at low speeds or in urban traffic environments to reduce pollution and save fuel. While a variety of primary and secondary power sources may be employed (including plug-in power), the ultimate focus of R&D seems to be on developing zero emission hydrogen fuel cells for hybrid EVs. Besides the basic series and parallel hybrid powertrain systems described earlier, hybrids are often configured to operate in a variety of cross configurations.
To give you an idea of the extent of HEV activity going on, listed below are U.S. market-released hybrid automobiles, and some of those (hopefully) becoming available soon. Note that specifications are drawn from a variety of data sources; because the HEV landscape changes almost daily, the information included is subject to change. For the most current data, it’s best to check with the OEs (See the sidebar listing online resources.)
U.S. Sold ICE Hybrid EVs
Honda: The Insight is a gasoline/electric 2-seater parallel HEV sports coupe featuring a 12 valve, 3 cylinder, 1 liter gasoline “VTECtm - E lean burn” engine. Insight’s engine provides 67 hp / 66 lb. ft. of torque, has variable valve timing, and a 10.8:1 compression ratio. The engine runs whenever the vehicle is underway, but shuts off under “idle-stop” situations.
Power assist comes from a 10 KW PM motor. The 5 speed manual trans and NiMH batteries help the Insight get 70 EPA test mpg and over 600 miles of driving range. A lightweight aluminum chassis and special low rolling resistance tires help to achieve this goal. The Insight demonstrates the fuel economy gains possible using hybrid technology. Insight’s Integrated Motor Assist (IMA) powertrain will be in the 2002 Civic, and will likely spread to other Honda models. A continuously variable automatic transmission will also be offered.
Toyota’s Prius is a 4-5 passenger sedan touted as the “vehicle for the millennium.” The gasoline/electric HEV features a 1.5 liter, 16 valve, 4 cylinder “low-rev” engine with reduced pumping losses and maximized thermal efficiency and fuel economy. A “high expansion ratio cycle” Atkinson cycle engine with variable delayed intake valve closing and 13:1 CR provide 70 HP / 82 lb. ft. of torque. The gasoline engine only runs when needed. Power also comes from a 33 KW / 258 lb. ft. PM electric motor. The planetary type “power-split” electronically controlled variable transmission (ECVT), regenerative braking, and NiMH batteries help current U.S. models get around 50–56 mpg and a driving range of 550-600 miles. (Images of the Insight and Prius appeared in the Summer 2001 ASE TechNews)
ICE Hybrid EV Automobiles under Development for the U.S. Market
Most industry experts recognize the heat-engine (ICE) powered hybrid EV will be an interim step towards achieving near pollutionfree (hydrogen powered) transportation and cargo handling.
Projections indicate that hybrid-powered vehicles will take market share from conventional vehicles over the next 10–20 years. Purchase prices will depend on economy-of-scale, and government and OE subsidies. While some hybrids offer modest fuel economy improvements; others meet or exceed the stringent 80-mpg Partnership for a New Generation of Vehicles (PNGV) benchmark. Heat engine hybrids coming in the next couple of years might include:
Ford: Escape (pictured left) is Ford’s hybrid SUV. Ford cites the Escape as getting “nearly 40 mpg under city driving conditions.” Prodigy is Ford’s family PNGV hybrid entry. It uses the energy efficient DIATA 1.2 liter, 4 cylinder diesel engine (which shuts off at vehicle standstill), a combination manual/automatic trans, and aerodynamic features to get nearly 80 mpg. The prodigy utilises Ford’s LSR (low storage requirement) powertrain technology to help reduce vehicle weight and meet PNGV objectives. Ford also has announced a HEV Explorer for 2004 using Volvo’s hybrid design system.
DaimlerChrysler: Durango hybrid SUV uses the “through the road” system for a modest 15% mpg gain and reduced tailpipe emissions. A 3.9 liter engine powers the rear wheels, and a 3 phase AC motor the front. Combined city/highway mileage of 18.6 mpg is reported.
The Dodge RAM hybridelectric pickup features a 15% mpg improvement, but can supply up to 20 kilowatts of electrical energy for auxiliary power use. Dodge’s ESX3 is an exciting PNGV 5 passenger family sedan entry which gets 72 mpg and features an all aluminum 1.5 liter diesel (6 gallon tank of zero-sulfur fuel) and lithium-ion batteries; its range is 400 miles.
DaimlerChrysler also will offer its 8 passenger Powerbox SUV with a 2.7 liter V-6 CNG fueled ICE, and a 70 hp electric motor to get 25 mpg GGE (gasoline gallon equivalent), and a 350 mile range. Rated SULEV, the Powerbox’s top speed is reportedly 125 mph, doing 0-60 in seven seconds.
General Motors: Precept (pictured right) –a highly technologically advanced PNGV 5 passenger mid-size 4WD car- is reported to achieve around 80 mpg, and over 90 on the highway using a 3 cylinder, 1.3 liter CIDI Isuzu diesel engine paired with two electric motors. One electric motor powers the front wheels and the other adds motive power as required or serves as a generator to recharge the batteries.
Power reaches the wheels through an automatically shifted manual trans, and the sleek Precept uses a 3 camera rear-vision system to eliminate drag associated with exterior rear-view mirrors.
GM is also working on its ParadiGM hybrid system, featuring a 3.6 liter V-6 powered hybrid SUV with 2 electric motors for a 20% mpg improvement. GM claims it will also offer a full sized Silverado/Sierra style HEV pickup with a 15% mpg improvement over the conventional ICE designs.
Pininfarina: Metrocubo is a mini 5 passenger sedan with a 505 cc, 2 cylinder Lombardini Motori MPFI engine, and a Siemens 35 KW liquid cooled motor which runs up to 10,000 rpm. Metrocubo has regenerative braking and a single-speed fixed ratio transmission.
Medium and H-D Hybrid EVs under Development for the U.S. Market
Medium and HD applications are also rapidly moving to HEV technology, and promise to provide an even greater return on HEV research investment.
Trucks and buses typically rack up highway mileage with its associated emissions, and stop-and-go urban vehicles operate where tailpipe emissions must be curtailed.
Both driving situations lend themselves to hybrid technology. Engine manufacturers like Cummins, GM and others, along with truck & coach and drive system manufacturers are working together to produce HEVs, often co-partnering with state and federal agencies. Along with clean fuel diesel ICEs, natural gas or propane fueled microturbines are being used for electro-motive power.
The military is testing a hybrid version of its HMMWV, powered by a 1.9 liter diesel and two 125 hp brushless DC motors—one for each axle. Using one-half the fuel normally needed, it gets around 15 mpg, can travel at 70 mph and climb a grade of 60% while fully loaded at 10 mph. It can operate in a battery-only “stealth mode,” or can serve as a 55 KW field generator.
Partial offering from other countries:
In Japan, Toyota’s Prius (supposedly achieving 80+ mpg) and Honda’s Insight are sold with somewhat different configurations and reconfigured software.
This summer Toyota will also sell the hybrid Estima van.
Nissan is offering the frugal compact 5 passenger Tino HEV minivan featuring a 1.7 liter gasoline engine, 17 KW motor, lithium-ion batteries and a continuously variable transmission (CVT). Hino is developing a hybrid bus for mountainous roads and extended highway travel. The HEV bus features a small supercharged diesel engine and a high degree of regenerative braking (used on downslopes) to save brake lining wear and provide almost complete battery recovery.
Hyundai is reportedly developing a 30 KW microturbine powered SUV called the Sante Fe.
In France, Renault has two new hybrid vans, the Modus and Operandi, which use only battery-electric power in the city, then switch to hybrid mode once outside city limits. Renault’s Koleos is an allterrain hybrid 4WD, 2 liter turbocharged SUV with lithium ion batteries powering a 30 KW motor driving the rear wheels.
In Italy, Fiat’s Multipla hybrid sedan can be plugged in overnight, and can be run in three different modes—including battery-only for ZEV compliance.
In Germany, BMW, Opel, DaimlerChrysler, Mercedes Benz, et al. are involved in hybrid EV research—check the web for further details.
To further shave weight, improve economy, and lower emissions of hybrid (and other) vehicles, you’ll see “ultracapacitors” being used not only for traction power reserve, but also at accessory locations (power door/trunk locks and window lift motors) to store up to 10X electrical energy reserve until it is needed. Flywheel “batteries” are still under development but look promising. Increasingly, the use of bi-directional multiplexing (Prius) and fiber optics communications between components is being used to save power and weight, and vehicles will soon switch to badly needed 42 volt charging / 36 volt battery systems.
The higher voltage system allows for the ultimate elimination of engine drive belts, and the addition of components/features like electronically controlled variable valve timing(no camshaft), electric steering and AC. Drive-by-wire and brake-by-wire systems will become commonplace as will navigation, communication, and collision avoidance systems.
If you think these hybrid electric vehicles with their futuristic designs and systems are way down the road, think again.
Some are already here, with more just around the corner. Technologies only dreamed of a few years ago are becoming reality.
Stick around—it’s an exciting time to be an automotive technician!
Want more Info on Hybrids?… Online Resources
Hybrid-electric vehicle (HEV) R&D is going on in many countries. To find out where and by which OEs, do an on-line data search using key words like “hybrid electric vehicle.” Listed below are some websites to get you started.
Hybrid Electric Vehicle Information
Vehicle-Specific HEV Sites
OE technician training — American Honda; Toyota Motor Sales USA
|U.S. Hydro-Electric Trucks and Buses On The Road (or soon to be)*
|Advanced Vehicle Systems||AVS-22 shuttle bus; CNG, LNG AVS-30,35, and 40 (microturbine), transit bus diesel|
|APS||22 to 40 foot transit bus|
|DUETS project||urban transit bus (3 types) NG|
|ISE Research-Thundervolt||TB-30H bus and NG & propane 801H truck (microturbine)|
|New Flyer||transit bus diesel|
|Novabus||urban transit bus diesel|
|Orion||urban transit bus diesel|
|TransTeq||45 foot (specialty) CNG transit bus|
|Van Hool N.V.||A308H (low floor) CNG shuttle bus|
|* This list is for information only and is not to be considered all-offered inclusive.|
Source: Rob Rodriguez (ASE)