Hybrid Compressed-Air and Internal-Combustion Engine

General Description

BridTech's hybrid compressed-air and internal-combustion engine (dual power cycle air hybrid engine) incorporates a novel dual power cycle involving the integration of the compressed-air power stroke and the internal combustion power stroke in the four-stroke cycle operation.

Whereas there is only one power stroke in the conventional four-stroke cycle, in the novel four-stroke dual power cycle of BridTech's air hybrid engine each down-stroke is a power stroke.

Overhead Exhaust Implementation

Cylinder-Wall Exhaust Implementation

The novel four-stroke dual power cycle is divided into six stages that include the compressed-air power stroke. This is achieved by the essentially sustained high-pressure compressed-air system.

With reciprocating piston compressors on the crankshaft, two compression cycles occur in each compressor cylinder for the charging of each power cylinder; therefore, with an equal number of compressor and power cylinders, a double charge is available to each power cylinder for a relatively high engine output even if compressed-air pressure is at the minimum. Compressor pistons/cylinders that are larger than the power pistons/cylinders may also be used for better engine performance.

BridTech's hybrid engine eliminates the conventional cooling system and replaces it with a compressed-air cooling system that recaptures the energy otherwise wasted (radiated) as heat.

BridTech's hybrid engine also readily incorporates a compressed-air regenerative braking system and a compressed-air starter system.

As illustrated in the tech specs, the primary choice is the use of a compressor mounted on the crankshaft. But the compressor need not be on the crankshaft; it can be driven by other means and mounted elsewhere; it can be in the transmission system where its regenerative braking function can be maximal.

Having the separate compressor cylinders also improves volumetric efficiency because air intake occurs in the relatively cooler compressor cylinders, as opposed to having the intake in the hot cylinders that reduces the air sucked in since the intake air quickly expands if hot cylinders are used.

These novel hybrid engine integrations result in very high engine efficiency.

The following illustration (from www.fueleconomy.gov) shows a breakdown of the energy losses incurred in the conventional internal combustion engine.

Of the total energy derived from the fuel, 62.4% is lost via engine heat radiation (i.e., via the cooling and exhaust systems), 17.2% via the idling operation, and 5.8% via the braking operation.

BridTech's hybrid engine addresses these main areas of operation where the conventional internal combustion engine incurs the highest energy losses.

An estimated 60-70% thermal efficiency is made possible by the dual power (compressed-air and internal-combustion) cycle of operation and by the regenerative braking system that together recover energy otherwise wasted.

The tech specs presented here point to the easy integration of a compressed-air-starter system or a compressed-air-assisted electric starter system. Obviously, this integration will allow reduced idling operations since the engine can be turned-off and turned-on in stop-and-go traffic.

BridTech's hybrid engine is mainly an in-cylinder fuel-injected and compression-ignition implementation. But it can obviously be implemented as a spark-ignition engine – since in-cylinder pressures can be suitably reduced by venting some of the air charge or by using appropriate compression ratios.

This hybrid engine is ideal in heavy trucks. But it can be readily used in cars.

The feasibility and viability of BridTech's hybrid compressed-air and internal-combustion engine will be obvious upon examination of the basic tech specs presented in this website.

BridTech's air hybrid engine differs from the various air hybrid engines researched or developed at UCLA, Brunel University, Lund Institute of Technology, ETH University, University of Waterloo, and the Scuderi Group. For a comparative study, see Fazeli's Development of a Novel Air Hybrid Engine.

The compressed-air hybrid engine is superior in many ways.

Air compressed using cheap electricity off the power grid and stored in compressed-air tanks, for the quick-charging of the hybrid compressed-air and internal-combustion engine vehicles, will reduce on-board fuel use. A compressed-air regenerative braking system for energy recovery is cheaper compared to an electric regenerative braking system.

The investments on the manufacturing and maintenance infrastructure for the compressed-air tanks and related systems will be minimal since most of the infra, especially the raw materials supply line, are already available. The raw materials (primarily steel) needed for the production of the compressed-air tanks and related parts are already in abundance. And air is plentiful.

In comparison, the electric hybrid technology will incur huge investments on the manufacturing and maintenance infrastructure needed. Moreover, the electric hybrid technology will likely have significant negative environmental impact because it will require increased mining activity for the raw materials needed to produce electric motors, storage batteries, and electrolytes.

In terms of recyclability, recycling steel is viable since the needed infra are already well-established – junk steel is easily recovered, stored in a yard, and loaded onto any truck; but recycling electrolytes is not viable since the needed infra are non-existent – used electrolytes need special recovery equipment and storage, and can't be loaded onto just any truck. In terms of the more general environmental impact, steel littered on the ground is generally clean, but electrolyte spilled on the ground is a dirty mess.

IP Status

[Patent Pending] – BridTech is in the process of securing the international patents for this IP.