Hybrid Truck Users Forum WG Selects Electric and Hydraulic Hybrid Suppliers
31 March 2008
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| Rexroth hydrostatic regenerative braking system (HRB) reduces fuel consumption by up to 25% and can be retrofitted as an add-on system even in vehicles without hydraulics. Click to enlarge. |
The members of CALSTART’s Hybrid Truck Users Forum (HTUF) Refuse Working Group have selected the supplier team of Crane Carrier/ISE/Bosch Rexroth to negotiate with for validation and testing of Class 7 & 8 heavy-duty electric hybrid and hydraulic hybrid refuse vehicles.
The hybrid trucks are expected to yield 30% to 50% reductions in fuel use with an accompanying reduction in emissions, to be demonstrated in chassis dynamometer and field testing. The working group members taking part in the hybrid refuse truck pilot project include the Department of Sanitation, City of New York; Solid Waste Management Department, City of Houston; and the City of Chicago.
Electric hybrid. Crane Carrier Company, working in conjunction with ISE Corporation, proposed a series hybrid electric refuse vehicle (HEV) using a self-contained hybrid drive assembly that can be easily mounted between the frame rails in most truck chassis. It replaces the conventional manual or automatic transmission assembly in the Crane Carrier LET2 chassis. The proposed HEV system uses components that have already been developed by ISE for the transit market in heavy 60 ft. articulated bus applications.
The HEV will use nickel-metal hydride (NiMH) batteries or ultra-capacitor packs to store energy recovered from the high number of braking cycles experienced by refuse collection vehicles during their normal operation. The HEV will also employ an onboard GPS and Remote Diagnostic Unit (RDU) providing the capability for real time performance monitoring and remote troubleshooting. The RDU conveys location, vehicle status and offers web-based access.
Hydraulic hybrid. Crane Carrier and Bosch Rexroth Corporation have proposed using Rexroth’s Hydrostatic Regenerative Brake (HRB) parallel hydraulic hybrid system to power their LET2 chassis. The HRB system will be integrated with the Heil refuse body hydraulic system for weight savings and more efficient packaging.
The HRB system uses a hydraulic pump/motor, connected to the driveline, to capture kinetic energy during vehicle braking. When braking, the pump/motor acts as a pump, absorbing energy from the driveline and imparting a retarding force on the drive wheels. The absorbed energy pumps hydraulic fluid into a nitrogen-pressurized accumulator. During acceleration the pressurized gas pushes fluid out of the accumulator and the pump/motor now acts as a hydraulic motor, assisting the engine and reducing the fuel required to launch the vehicle.
Resources
Simon J. Baseley, Christine Ehret, Edward Greif, Markus Kliffken; Hydraulic Hybrid Systems for Commercial Vehicles (SAE 2007-01-4150)
Easily mounted, can be retrofitted...municipal buses and trucks are an obvious market. With the downturn in the economy, many state and local governments will face decreased revnues. This would alleviate some of the fuel costs and save taxpayer dollars over the longrun.
Posted by: allen_xl_z | 31 March 2008 at 10:54 AM
Only if the maintenance costs are very low.
Posted by: Reality Czech | 31 March 2008 at 12:10 PM
Hydraulic hybrid systems should be cheaper to install, but there are wear and tear issues: the hydraulic fluid is stored at pressures as high as 700 bar and, the nitrogen in the accumulators will reach high temperatures during rapid recuperative braking. It will cool down almost as quickly during acceleration events. The pressure and temperature swings place a lot of stress on the materials involved.
Using NiMH batteries for a system designed primarily for recuperative braking makes little sense. Ultracaps are the way to go for an implementation that is more expensive but also solid state (except for the motor/generator).
Posted by: Rafael Seidl | 31 March 2008 at 12:48 PM
Finally an appropriate use for a prius. Garbage hauler.
Posted by: lol | 31 March 2008 at 12:58 PM
Beijing ordered some 3000 EV grabage trucks last year. Any news on how they are doing?
Posted by: Harvey D | 31 March 2008 at 03:04 PM
I refuse to believe these trash talkers whose only output is garbage.
Posted by: John | 31 March 2008 at 03:24 PM
Retrofitting, if economical, seems like a huge market/potential benefit to me.
Posted by: Nick | 31 March 2008 at 06:51 PM
Retrofits in general sound like a good idea until you think of all the makes, models and years of vehicles that you would like to retrofit. At some point you might choose just the most popular recent models to target.
Felix Kramer on one of the business sites hinted that there would be a wave of hybrid retrofit companies. I am doubtful, but still waiting to see. If this were the case, we would see retrofits of trucks and buses first I would think. The replacement cost and fuel usage is higher there.
There was a story about independent truckers in the U.S. being affected by the high price of fuel. They wanted a "pass through" surcharge for fuel. At some point it might be better for everyone to retrofit the trucks to get better mileage.
Posted by: sjc | 02 April 2008 at 02:24 PM
Ultra capacitors do not store enough energy and are super expensive for the energy that they do store. NiMH batteries store far more energy and can move a vehicle for more than a few yards without engine power.
Any vehicle that has a home for the night should use an array of ZEBRA batteries so that a lot of the vehicles work can be done as a plug in hybrid.
Hydraulic hybrids may be the cheapest answer to non plug in hybrids. Pressure tanks are cheap and simple compared to hundreds of Ultra Capacitors with special circuits.
See PARRY PEOPLE MOVERS for a rail hydraulic flywheel hybrid.....HG....
Posted by: Henry Gibson | 25 April 2008 at 12:03 AM