WO1983001980A1

WO1983001980A1 - Inlet-air conditioning for internal combustion engines

Info

Publication number: WO1983001980A1
Application number: PCT/GB1982/000338
Authority: WO
Inventors: Louis Reginald Skeels
Original assignee: Louis Reginald Skeels
Priority date: 1981-11-30
Filing date: 1982-11-30
Publication date: 1983-06-09
Also published as: EP0096697A1; GB2120726A; JPS58502014A; GB8318229D0

Abstract

A method of and apparatus for operating an internal combustion engine so as to condition the inlet air by mixing a main and a subsidiary stream of air, respectively at temperatures which differ by at least 20o C. This causes the formation of water droplets which are carried by the air into the engine with beneficial effects, inter alia reduced fuel consumption and pollutant emission and the ability to run on lower octane fuel. The subsidiary air stream is heated by exchange of heat with the exhause gases and is introduced into the air cleaner of the engine in opposition to the radially inward flow therein of main intake air so ensuring thorough mixing.

Description

INLET-AIR CONDITIONING FOR INTERNAL COMBUSTION ENGINES

FIELD OF THE INVENTION

The invention relates to internal combustion engines including compression ignition engines and rotary engines

and more particularly, to a method and apparatus for

conditioning the inlet air thereof.

BRIEF DISCUSSION OF THE PRIOR ART

The prior art contains a vast number of proposals

for conditioning the inlet air of internal combustion

engines the the object of improving their efficiency and

operation. '

British Patent Specification No. 773115, for example,

describes admitting hot air and/or water vapour to the

fuel/air mixture downstream of the carburettor to form a

tubular- curtain in the fuel-intake opening of an internal

combustion engine, capable to taking up the fuel condensate particles on their way from the carburettor to the working

cylinder, evaporating the particles and then returning the

evaporated condensate to the fuel air mixture. It is said,

that this ensures practically complete combustion of the

fuel, reduces the fuel compensation and improves the

working conditions for the engine yielding a longer engine . life.

British Patent Specification No. 766303, on the other

hand proposes mixing with the cold inlet air, a

controlled amount of hot air tapped from a heating system for the interior of the vehicle in response to the temperatur of air upstream of the carburettor. The objection of this proposal is to p ent the formation of ice in the carburettor.

Other specifications such as British Patent Specification No. 1525021 and British Patent Specification Nos. 1400072 and 2081377A propose adding steam to the

inlet air of internal combustion engines to permit the use of fuel of a lower octant rating, to reduce fuel consumption and pollutant emission.

One disadvantage of previous proposals is that, often complex, modifications are required to existing engines and substantial redesign would be necessary in order to build engines incorporating the necessary

features , which is one reason why most previous proposals have not become widely used. SUMMARY OF THE PRESENT INVENTION

I have now found that good results may be achieved without the need to inject or otherwise add water or steam

to the inlet air since it is possible so to condition the

air at inlet that the water vapour present in the ambient

air at inlet to the engine is condensed to form water

droplets.

What I propose, in accordance with one aspect of the present invention is to condition the inlet air fed to

the engine by mixing streams of air at different temperature to form water droplets which are carried by the air into

the engine. A subsidiary stream of air is preferably

drawn through a heat exchanger for the exchange of heat with the exhaust gases or indeed with the engine coolant

or any other convenient source of heat, prior to mixing with the main intake air. Mixing preferably takes

place upstream of the venture of the carburettor (in the case of the petrol engine) and preferably such that a cross-flow of the main and subsidiary air stream is obtained to produce turbulance and hence ensure thorough mixing.

According to another aspect of the invention I propose an internal combustion engine having means for supplying fuel and air to the combustion chamber or

_* chambers and an exhaust system for the combustion gases,

and comprising a main air intake and a subsidiary air intake including a heat exchanger for heating the subsidiary air by exchange of heat with, for example, the

exhaust gases and through which a subsidiary stream of

air is drawn, the subsidiary air intake being connected to the main air intake, whereby, upon mixing of the main and

subsidiary air streams at different temperatures, water droplets form and are carried by the air into the engine.

Preferably, mixing takes place downstream of an air cleaner element of the engine and disposed in the main

air intake thereof. Normally, the air cleaner element is annular and it is preferred to connect the subsidiary

air intake to the main air intake by a pipe disposed within, preferably, centrally within, the air cleaner

element and to provide, in an end portion of the pipe, transverse openings, that is to say openings in the wall

of the pipe, such that subsidiary air is directed against the radially inward flow of main intake air through the

air cleaner element.

For best results the difference in temperature between the main and subsidiary air streams should be greater than 20 C and, preferably, greater than 30 C. This can be achieved in a variety of ways, for example, by adjusting the flow through the subsidiary air intake

(i.e. by varying the size thereof) or by adjusting the extent to which the subsidiary air stream is cooled in

passing from the heat exchanger to the point of mixing.

In this connection, the length of the pipe and the material

used can be varied according to the requirements of a particular engine and/or vehicle. Alternatively, expansion chambers or condenser units may be incorporated

in the subsidiary air intake. Relatively minor

adjustments can produce marked changes in the cooling

effect, bearing in mind the flow of air through the engine compartment of a vehicle travelling at speed.

Although it might be thought that the difference in

temperature between the main and subsidiary air streams

will depend largely upon the ambient condition this is

not so. One reason being that the ambient air is cooled

as it is drawn into the main air intake. Also, on hot days the engine tends to run hotter so that a corresponding

increase in the temperature of the subsidiary air stream tends to compensate for an increase in the temperature of the main air stream.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the present invention will now be described by way of example with reference to the

accompanying drawings of which:

Figure 1 is a schematic view of an internal combustion engine fitted with apparatus according

to the present invention; and

Figure 2 is a cross-section through the air filter of the engine shown in Figure 1, illustrating how the main and subsidiary air streams are mixed.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The engine, shown schematically in Figure 1, has an

air filter 10 mounted, as is usual, above the carburettor 12, the combustion air being drawn from the filter 10 through a venture 14 at a rate controlled by a butterfly valve 16. In addition to the main air intake to the- air filter at

18, a subsidiary air intake isprovided, this including a heat exchanger 20, in the form of a collar 22 clamped to or

otherwise held in intimate contact with the exhaust manifold 24 of the engine, and connected by a pipe 26 to the air filter. The pipe 26 enters the air filter 10 in the

centre of the top thereof and passes downwardly within the annular air cleaning element 28 as shown In Figure 2. The end of the pipe 26 is closed but openings are formed in the wall thereof such that a subsidiary stream of air, which is drawn, partly by engine suction and partly by induction due to the main air intake flow , issues as

indicated by the arrows in Figure 2, radially outwardly in opposition to the flow of main intake air passing

radially inwardly through the annular air cleaning element 28.

This arrangement gives rise to turbulance and hence ensures

thorough mixing of the main and subsidiary streams of air. The pipe 26 connecting the heat exchanger 20 and

the air filter 10 may be formed of metal, typically

copper, or in part of a material having a lower thermal

conductivity, (for example, rubber) and further, may incorporate condenser or expansion chambers (not shown)

as required to cool the subsidiary stream of air, after heating, and as appropriate to the particular engine, vehicle and/or operating conditions concerned, to a

temperature higher than the temperature of the main

intake air by an amount sufficient to cause condensation

of at least some of the water vapour present in the

ambient air. In practice the difference in temperature 'of the main and subsidiary air streams will be greater than 20 C and this is largely independent of the ambient conditions.

Tests on a wide range of vehicles in which the internal combustion engine has been modified in accordance with the present invention indicate that fuel consumption can

readily be improved by 10% and in some cases by as much

as 30%.

OM

Claims

1. An internal combustion engine having means for

supplying fuel and air to the combustion chamber or chambers

and an exhaust system for the combustion gases, and

comprising a main air intake and a subsidiary air intake

including a heat exchanger for heating the subsidiary

air byexchange of heat with, for example, the exhaust gases and through which a subsidiary stream of air is

drawn, the subsidiary air intake being connected to the main air intake, whereby, upon mixing of the main and subsidiary air streams at different temperatures, water

droplets form and are carried by the air into the engine.

2. An engine according to claim 1 wherein mixing takes place downstream of an air cleaner element disposed in the main air intake of the engine, but upstream of a butterfly valve, if any.

3. An engine according to claim 1 or claim 2 wherein the subsidiary air intake is connected to the main air

intake by a pipe disposed within an annular air cleaner

element in the main air intake and terminates in an end portion having openings In the walls thereof, such that subsidiary air is directed against the radially inward flow

of the main intake air through the air cleaner element.

4. An engine according to any one of claims 1 to 3 wherein the connection between the subsidiary air intake

heat exchanger and the main air intake is adapted to

cause cooling of the heated subsidiary air issuing from

the heat exchanger to a desired mixing temperature.

5. Apparatus intended to be fitted in combination

with an internal combustion engine,to produce an internal combustion according to any one of the preceding claims.

6. A method of operating an internal combustion engine

comprising conditioning the inlet air fed to the engine

by mixing streams of air at different temperatures so as to form water droplets which are carried by the air into the engine.

7. A method according to claim 6 wherein the difference in temperature between the streams of air is greater than 20 C and, preferably, greater than 30 C.