Hybrid Electric and Hybrid Hydraulic Technology Applications in Off-Road Vehicles

Glossary

Off-road vehicle:

An off-road vehicle is a vehicle which is capable of driving on and off paved or gravel surface. Vehicles that do not travel public streets or highways are generally termed off-highway vehicles, e.g., tractors, forklifts, cranes, backhoes, bulldozers, and golf carts.

Drive cycle:

It is a relationship of either speed versus time or power versus time, for a particular vehicle which is driven in a given road profile. The road profile can be city streets, highways, steep grade, or some chosen mixed combination of these or other profiles, which will be predefined.

Internal combustion engine (ICE):

ICE is the one in which combustion of the fuel (e.g., gasoline, etc.) takes place internally inside a cylinder or other enclosed space using spark ignition or compression ignition to some combustible gas which will expand and produce high pressure which will produce mechanical power. ICE is thus a converter of chemical energy in mechanical energy.

Diesel IC engine:

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Appendices

Appendix 1: Specifications of Komatsu Mining Truck

Information given below is based on the Komatsu data sheet [3], but for an earlier version of the system. Although exact details on the systems are normally proprietary information of the manufacturers, some commonality can be noticed between these systems and some reasonable idea about the sizes of the components can be obtained, based on the information in these publicly available specification sheets.

AC current
Alternator	GTA-39
Dual impeller in-line blower	453 m3/min 16,000 cfm
Control	AC torque control system
Motorized wheels	GDY106 AC induction traction motors
Final gear ratio to wheel	32.62:1
Speed (maximum)	64.5 km/h 40 mph

Appendix 2: Accumulators

Accumulators basically consist of cylinders which have valves to let the gas in or out with appropriate safety mechanisms. Other types of accumulators [14] are the bladder or diaphragm types as shown in Fig. 20a, b. Bladder type of accumulator consists of a flexible bladder submerged in an incompressible fluid. Inside the bladder there is a gas which can be pressurized to compress or de-pressurized to expand. There are several working mechanisms for the accumulators e.g. in the hydro-pneumatic scheme the liquid pushes a piston, which then pushes a gas stored in the cylinder and compresses it, whereby energy is stored. Piston separates the liquid from the gas.

Fig. 20

(a) Diaphragm accumulator (b) Bladder accumulator

In the diaphragm accumulator a diaphragm B is pushed by some liquid from the bottom, which then changes the volume of the gas in the upper part of B i.e. between the diaphragm and the cylinder itself. In a bladder accumulator, the bladder B contains the gas which can be compressed. When the liquid enters the cylinder from the bottom, the bladder can expand or contract, thus energy can be stored in the gas when compressed and taken out from the gas when expanded. The energy is transferred through the fluid itself.