NYC refuse trucks to test hydraulic hybrid technology
Bosch Rexroth reports that it has been selected, along with Crane Carrier Company and ISE Corporation, by Calstart’s Hybrid Truck Users Forum (HTUF) Refuse Working Group to examine and test the use of hybrid vehicle technology in refuse trucks. The companies expect the hybrid trucks to demonstrate between 30% and 50% reductions in fuel and emissions use during testing.
Rochester Hills, MI — Bosch Rexroth reports that it has been selected by Calstart’s Hybrid Truck Users Forum (HTUF) Refuse Working Group to examine and test the use of hybrid vehicle technology in refuse trucks. Rexroth will contribute its Hydrostatic Regenerative Brake (HRB) parallel hydraulic hybrid system to the project, which will be deployed and tested in the city of New York.
Bosch Rexroth, Crane Carrier Company and ISE Corp. make up the supplier team for the HTUF project. The companies expect the hybrid trucks to demonstrate between 30% and 50% reductions in fuel and emissions use during testing. The field tests are designed to authenticate both the technical and economical characteristics of the HRB system. The team expects test results to demonstrate HRB’s potential, eventually leading to large scale deployment of in-service and new vehicles.
Bosch Rexroth says the HRB system will power the Crane Carrier LET2 chassis in the trucks, and will be integrated with the Heil refuse body hydraulic system for weight savings and 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 drivewheels. It then uses the absorbed energy to pump hydraulic fluid into a nitrogen-pressurized accumulator. The accumulator is a tank containing inert gas that is compressed by the incoming fluid. During acceleration the pressurized gas pushes fluid out of the accumulator and the pump/motor then acts as a hydraulic motor, assisting the engine and reducing the fuel required to launch the vehicle. The overall process is referred to as regenerative braking.
Hydraulic hybrids are better equipped to cope with the extremely high power-handling requirements of regenerative braking, and they require fewer energy conversion steps that reduce efficiency. In this way, hybrid systems have the potential to capture a larger portion of the braking energy and make use of it more effectively.
Bosch Rexroth’s HRB system includes a hydrostatic hybrid drive which uses the considerably higher performance of hydraulics compared with available batteries to substantially reduce fuel consumption even in heavy commercial vehicles.
When the driver presses the brake pedal, a hydraulic unit integrated in the drivetrain presses the hydraulic fluid into a high-pressure reservoir. The resulting resistance makes the vehicle decelerate. When accelerating, the hydraulic pressure reservoir is controlled electronically to release the pressure and it relieves the load on the diesel engine. As a result, the engine consumes less fuel, generates less exhaust gases, and functions more quietly.
The compact Rexroth HRB is ideal for use in various commercial vehicles. The HRB can be integrated and even retrofitted in the chassis as an add-on system, without major modifications.
The system reduces fuel consumption by up to 25% in vehicles used for very short distances such as urban buses, garbage trucks, fork lift trucks, or delivery vehicles driven in city traffic. Fuel consumption can also be reduced considerably in other commercial vehicles and trucks used for intercity service.
Each time a driver brakes, the HRB system stores energy which would otherwise be lost. The hydrostatic hybrid drive functions almost maintenance-free and wear-free compared with electric hybrid drives. For example, it is not necessary to regularly change the battery. In addition, the HRB also improves the acceleration of the vehicle. The additional drive energy allows vehicles to be equipped with smaller diesel engines and therefore further reduce fuel consumption and emissions.
All Rexroth HRB components are based on standard components from the manufacturer’s current product portfolio. Prototypes of the Rexroth hydrostatic hybrid drive are currently being tested in on-road vehicles.
— Edited by C.G. Masi , senior editor
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