GB2259326A

GB2259326A - Water injection in supercharged intercooled engines

Info

Publication number: GB2259326A
Application number: GB9118191A
Authority: GB
Inventors: Robert Joel English
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-08-23
Filing date: 1991-08-23
Publication date: 1993-03-10
Anticipated expiration: 2011-08-23
Also published as: GB9118191D0; GB2259326B

Abstract

Water or aqueous alcohol solution 6 in a pressure vessel 5 is pressurised when the engine is in operation by being connected upstream of the intercooler 3 and is injected via a nozzle 8 downstream of the intercooler. <IMAGE>

Description

WATER INJECTION SYSTEM FOR SUPERCHARGED ENGINES HAVING CHARGE Ii?EPCOOLERS The reported benefits of water, or aqueous alcohol,injection for internal combustion engines is well known and up to the present the process has been employed on a range of power units extending from automobiles to aircraft. It is known that the injection of water or a mixture of water and a soluble alcohol to the intake charge of an engine at the opti:ninn time and in the optimum amount can suppress pre-ignition or detonation and thereby power output is increased.This effect is particularly true of engines where the charge pressure has been increased beyond that of atmospheric by the use of turbo- or superchargers. Unfortunately the act of increasing the charge pressure also increases the charge tenperam---e and the kinetics of this is to increase the tendancy of the fuel mixture to detonate. It is inpcrtant therefore that a system be in operation in a supe-ciurbed power unit which can control detonation thereby governing and optimizing the power output from any given octane rated fuel.In the past many methods of control have been derived and the literature teaches that in 1962 Oldsmobile Limited introduced a water injection system on their Oldsmobile F. 85.Jet Fire which employed a mixture of water and methanol wheras in the late 1970's Saab Limited marketed a retrofit kit for water injection on their model 99Turbo with a claim that the increased boost was another 30 Tip over standard.

When a power unit is intercooled it is necessary to inject the liquid after the intercooler and into the pressurised tract of the intake manifold. Equilibrium is then established between the increase in cylinder pressure and the decrease in intake charge temperature due to the change of state of the injected liquid phase on one hand and the opposite effects of pressure and temperature reductions due to the presence of the intercooler. There is a resultant pressure decrease across the intercooler when such injection is carried out and it wi1l vary depending upon the temperature at the intercooler inlet, the ambient temperature and the efficiency of the intercooler. It can be appreciated therefore that there will be a pressure drop which is proportional to the temperature decrease across the intercooler.

The higher pressure end of the pressure drop is at the inlet of the intercooler and it can be used to force liquid from a sealed reservoir to the lower pressure end of the intercooler or to the intake manifold of the engine power unit. It is therefore possible to devise 2 water, or water-alcohol,injection system which will inject fluid w:2en it is most required i.e. when the compressor outlet temperature is at its highest maximum boost conditions and which will vary the quantity of fluid injected depending upon the pressure drop across the intercooler. The pressure regime across the intercooler ranges from about zero at around no boost to high pressure at a high boost.The present invention provides a simple system to accomplish these beneficial effects and accordingly there is provided a sealed fluid container,or reserv oir,which is pressurised by the high boost pressures at the inlet of the intercooler so that the gas space in the vessel responds to the inlet pressure variations and transmitts this to the liquid and hence to an outlet jet in a manner analogous to the Bramah Press.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which: Figure 1 shows in diagramatic perspective a sectional elevation of the reservoir and jet as they are fitted across the intercooler of the turbo-charged engine.

Referring to the draing the air compressor 1 forces its outlet charge to the inlet 2 of the intercooler 3 and in doing so the charged is partly cooled by the radiating effect of its surface. At the point 4 in the pipeline the inlet pressure of the intercooler 3 is conducted to the ton eas space of the fluid reservoir 5 and in doing so the fluid 6 is forced Up the tmibe 7 an hence into the gas o -let of the intercooler where it discharges via the jet 8. In root power units there will be a carburettor or a throttle flap and ths is designated 9 in this engine 10.

This system is simple to fabricate and is cheap and easy to fit and involves only 2 pressure take-off point, some pipirt,a suitably strong licuid container and an injection nozzle. In experimental tests the described device has been very successfully used on two turbocharged intercooled car engines one of which was carburetted and the other fuel injected. The Figure 1 has no inherent design implications and is simply presented to illustrate that the jet 8 of selected constant orifice area will deliver ejected fluid in a volw^ne pronortional to the varying pressure generated at 4 when the power unit is in operation.

Claims

CLARS

1. A fluid injection system for supercharged engines having charge intercoolers comprising a sealed fluid reservoir which is pressurised by the high boost pressures at the inlet of the intercooler so that the gas space in the reservoir responds to the inlet pressure variations at the intercooler and transmlitts these to the fluid and hence to an outlet jet at the intercooler.

2. A fluid injection system according to Claim 1 wherein the supercharged. engine is of the carburatted fuel feed type.

3. A fluid injection system according to Claim 1 wherein the supercharged engine is of the fuel-injection type.

4. A fluid injection system according to any of the Claims 1 to 3 wherein the fluid tc be injected is either water or an aqueous alcohol sol'ticn.

5. A fluid injection system for supercharged engines having charge irtercoolers substantially as described herein with reference to Figure 1 of the accompanying drawing.