GB2081377A

GB2081377A - Supplying steam to I.C. engines

Info

Publication number: GB2081377A
Application number: GB8024673A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-07-28
Filing date: 1980-07-28
Publication date: 1982-02-17
Also published as: GB2081377B

Abstract

A water boiler 1 around an exhaust pipe 2 is supplied by a vertically adjustable float chamber 17 for maintaining a predetermined water level in the boiler and the space in the boiler above the water level is connected via a pipe 10 to an air intake of the engine downstream of an air cleaner element so that wet steam passes along the pipe to join the air entering the air intake. Air is drawn through holes 14 to mix with the steam. <IMAGE>

Description

SPECIFICATION Internal combustion engine and device for supplying water vapour thereto This invention relates to internal combustion engines including compression ignition engines and rotary engines, and a device for fitting to said engines for supplying water vapour to the air intake.

A device of this type has been described in UK Patent No. 1400072 and what is said in that patent about the general nature and uses of devices of this type will not be repeated here. However, there is still a need for improvements in devices for supplying water vapour to the air intake of an internal combustion engine with a view to reducing fuel consumption, reducing pollutant emission and, in the case of petrol engines, permitting use of fuel of a lower octane rating.

It has now been found to be desirable to make provision for altering the volume of the water in the stream generator or boiler as this affects the fuel/ water ratio taken in by the engine. The fuel/water ratio is the ratio of the volume of fuel to the volume of water (in the form of wet vapour) fed to the engine over a period of use. The optimum ratio has been found to be about 5:1 for diesel (compression ignition) engines running on fuel oil and about 8:1 for petrol engines. On the other hand, in contrast to PatentNo. 1400072, it has not now been found necessary to supply heat to the boiler only below the water level. It has also been found to be desirable to use a boiler of low volume so that steam is generated quickly after start-up.However, provision has still to be made for maintaining a predetermined water level in the boiler (bearing in mind that the water surface will be turbulent).

According to one aspect of the invention, there is provided an internal combustion engine having at least one combustion chamber, means for supplying fuel and air to the chamber, and an exhaust system to exhaust combustion gases from the chamber, which comprises a water boiler in heat-exchange relation with the exhaust system, a vertically adjustable float valve for automatically maintaining a predetermined water level in the boiler, the space in the boiler above the water level being connected via a pipe to an air intake of the engine downstream of an air cleaner element but upstream of a butterfly valve if any, and also to the atmosphere by means of a scavenging hole, and the arrangement being such that in use the water in the boiler is boiled by the heat transferred from the exhaust system and wet steam passes along the pipe to join the air entering the air intake.

According to another aspect of the invention, there is provided an internal combustion engine having at least one combustion chamber, means for supplying fuel and air to the chamber, and an exhaust system to exhaust combustion gases from the chamber, which comprises a water boiler in heat-exchange relation with the exhaust system, means for automatically maintaining a predetermined water level in the boiler including a water inlet reservoir beside the water boiler and connected thereto by a plurality of horizontal tubes above one another, the space in the boiler above the water level being connected via a pipe to an air intake of the engine downstream of an air cleaner element, but upstream of a butterfly valve if any, and also to the atmosphere by means of a scavenging hole, and the arrangement being such that in use the water in the boiler is boiled by the heat transferred from the exhaust system and wet steam passes along the pipe to join the air entering the air intake. Preferably the space in the boiler above the water level is connected by a tube to the upper part of the reservoir so that steam is withdrawn through the upper part of the reversoir, the pipe being connected to the reservoir. In this preferred arrangement, the scavenging hole or holes can be in the upper part of the reservoir.

The invention also extends to devices for fitting to internal combustion engines so that the engines are as defined in the preceding two paragraphs.

An embodiment of the device according to the invention will now be described by way of example with reference to the accompanying drawings in which the device is shown diagrammatically in cross section, Figure 1B being a continuation upwards from Figure 1A.

The device shown in the drawing is intended for an agricultural tractor with a vertical exhaust or stack pipe. As shown the annular boiler or steam generator 1 is integral with the stack pipe 2 but for a conversion unit an annular boiler 1 may be used which has an inner cylindrical wall through which the stack pipe 2 may be passed in close fitting relation.

The annular boiler 1 has a drain plug 3 for draining and flushing out and is connected by seven horizontal tubes 4 of relatively small bore to a cylindrical water inlet reservoir 5. The reservoir 5 has a drain plug 6 and in this embodiment also serves as a steam chamber, a relatively large bore steam outlet pipe 7 being arranged to connect the upper part of the boiler 1 and the upper part of the reservoir 5. The pipe 7 is inclined so that any condensed steam runs back to the boiler. A pipe 10 leads via an intermediate cylindrical condenser unit 11 to an air cleaner unit 12 downstream of the element 13. The steam should be fed to the air intake upstream of the butterfly valve (not shown) if any - some compression ignition engines with injectors do not have a butterfly or other control for the air intake.The condenser unit 11 can be simply a cylindrical container which permits the stream to cool. The temperature at which steam is fed by the device should be about 30"C i.e. the steam is wet steam or water vapour.

The upper part of reservoir 5 has three air holes 14 which serve to mix atmospheric air with the steam to dilute and cool it. The size of the holes will depend on the size and nature of the engine but three 1/2 inch holes are generally suitable for diesel engines and three 3/8 inch holes are generally suitable for petrol engines.

Secured to the side of the reservoir 5 is a bracket 15 having a vertical slot through which a bolt 16 adjustably mounts a float valve assembly 17 which is fed from a water tank (not shown) through a flexible pipe 18 and maintains a constant water level in the reservoir 5 and boiler 1 via a flexible pipe 19. It is thus an easy matter to adjust this water level by moving the float valve assembly 17 up and down.

The horizontal tubes 4 maintain the water level in the boiler but reduce convection flow into the reservoir (as compared to a single large tube) and thus permit more rapid water heating in the boiler.

The air holes 14 need not be in the reservoir 5; it is sufficient that provision is made for sucking air into the air intake along with the steam. It is also not necessary that steam drawn from the boiler passes through the reservoir.

In an alternative embodiment the boiler is of half annular (semicircular) section and is provided with a clamp for clamping to an exhaust pipe.

When determining the size of the air holes 14, it is important that they be matched to the maximum suction applied by the air intake system of the engine. If they are too small, the water level in the boilerwili tend to rise when suction increases on opening the throttle. This leads to temporary cooling of the water and loss of steam production for a second or two; in other words, there will be a flat spot. On the other hand, if the air holes 14 are too large, this will lead to overdilution of the steam. In practice substantially all of the steam produced is drawn into the air intake of the engine; this is why the volume of water in the boiler and hence the rate of production of steam has been found to be important in determining the fuel/water ratio. It should be noted in this connection that the fuel/ water ratios referred to above are those for the United Kingdom. In drier climates where the relative humidity is lower, the ratio for petrol engines may, for example, be reduced from about8:1 to about6:1.

Claims

1. An internal combustion engine having at least one combustion chamber, means for supplying fuel and air to the chamber, and an exhaust system to exhaust combustion gases from the chamber, which comprises a water boiler in heat-exchange relation with the exhaust system, a vertically adjustable float valve for automatically maintaining a predetermined water level in the boiler, the space in the boiler above the water level being connected via a pipe to an air intake of the engine downstream of an air cleaner element but upstream of a butterfly valve if any, and also to the atmosphere by means of a scavenging hole, and the arrangement being such that in use water in the boiler is boiled by the heat transferred from the exhaust system and wet steam passes along the pipe to join the air entering the air intake.

2. An internal combustion engine as claimed in claim 1, which comprises a water inlet reservoir beside the water boiler and connected thereto by a plurality of substantially horizontal tubes above one another.

3. An internal combustion engine having at least one combustion chamber, means for supplying fuel and air to the chamber, and an exhaust system to exhaust combustion gases from the chamber, which comprises water boiler in heat-exchange relation with the exhaust system, means for automatically maintaining a predetermined water level in the boiler including a water inlet reservoir beside the water boiler and connected thereto by a plurality of horizontal tubes above one another, the space in the boiler above the water level being connected via a pipe to an air intake of the engine downstream of an air cleaner element, but upstream of a butterfly valve if any, and also to the atmosphere by means of a scavenging hole, and the arrangement being such that in use the water in the boiler is boiled by the heat transferred from the exhaust system and wet steam passes along the pipe to join the air entering the air intake.

4. An internal combustion engine as claimed in claim 2 or 3, wherein the space in the boiler above the water level is connected by a tube to the upper part of the reservoir so that steam is withdrawn from the upper part of the reservoir.

5. An internal combustion engine as claimed in claim 4, wherein the tube is inclined so that any condensed steam runs back to the boiler.

6. An internal combustion engine as claimed in claim 4 or 5, wherein the scavenging hole is in the upper part of the reservoir.

7. A device for fitting to an internal combustion engine, the device having the features specified in any preceding claim.

8. A device for fitting to an internal combustion engine substantially as hereinbefore described with reference to the drawing.