Computer simulations and literature survey of continuously variable transmissions for use in buses. Final report, June-December 1981

Technical Report · Mon Nov 30 23:00:00 EST 1981

OSTI ID:5155529

Barrows, T

Numerous studies have been conducted on the concept of flywheel energy storage for buses. Flywheel systems require a continuously variable transmission (CVT) of some type to transmit power between the flywheel and the drive wheels. However, a CVT can provide some fuel economy benefit with or without an energy-storing flywheel, which is the focus of this report. This computer study and literature review is intended to provide insight into the potential applicability of CVTs to buses. It has been suggested that such transmissions may be of interest for two reasons: (1) simple substitution of a CVT in the place of a conventional transmission may offer fuel savings by allowing the engine to operate at its most efficient speed and (2) the combination of a CVT and a flywheel allows regenerative braking, in which the vehicle kinetic energy during deceleration is captured for later re-use. This computer study and literature survey considers several examples of CVTs in buses, both with and without flywheel energy storage, and finds a predicted energy savings of 10 to 32 percent. The analysis focuses on the use of a CVT alone, without regenerative braking. Computer simulations are made to compute the fuel use of a bus with two different CVTs - one with a ratio range of 6, and the other of an infinite ratio range. For the former, assuming an efficiency of 85 percent, a fuel savings of 12 to 22 percent is predicted, depending upon the driving cycle. It is shown that a substantial part of this saving arises from the simple fact that the accessories operate at a lower speed. For this reason, a separate study of accessory speed control has been conducted, yielding a predicted fuel saving of as high as 17 percent. The report concludes that such accessory speed control may represent an attractive way to reduce fuel consumption. In comparison with the CVT, the concept is more compatible with present bus technology.

• Research Organization: Department of Transportation, Cambridge, MA (USA). Transportation Systems Center
• OSTI ID: 5155529
• Report Number(s): PB-82-156795; DOT-TSC-UMTA-81-54
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
330500* -- Advanced Propulsion Systems-- Flywheel Propulsion
330602 -- Vehicle Design Factors-- Engine-Transmission Matching
BUSES
COMPUTERIZED SIMULATION
DOCUMENT TYPES
ENERGY CONSUMPTION
ENERGY STORAGE
FLYWHEEL-POWERED VEHICLES
FLYWHEELS
FUEL CONSUMPTION
FUEL ECONOMY
MACHINE PARTS
MECHANICAL ENERGY STORAGE EQUIPMENT
MECHANICAL TRANSMISSIONS
REVIEWS
SIMULATION
STORAGE
TRANSPORTATION SYSTEMS
VEHICLES