Field of the Invention

The present invention relates to a fuel system purge method and apparatus. More particularly, the method and apparatus of the present invention are intended for use in respect of fuel systems diesel engines.

Background Art

A known problem associated with the operation of engines running on fossil fuels are the deposits of gums, lacquers, varnishes, waxes and carbon which are deposited in the fuel lines, fuel pump, fuel rail, fuel injectors, valves, pistons and cylinder walls of those engines. Further, diesel fuel is prone to the formation of water through condensation whilst in storage as it is hygroscopic. The resulting combination of water and diesel provides an environment that is ideal for the growth of fungal and bacterial populations. This can result in contamination of the fuel and the clogging of filters, injectors and resulting poor performance and production of black smoke during combustion. Further, engines running on diesel contaminated with water and fungus are typified by poor performance, poor fuel economy, difficulties in starting, rough idling and the production of excessive smoke.

Existing fuel system purge methods and apparatus utilise a single reservoir to which a mixture of fuel and purge fluid is added at some preconceived ratio. The engine is then run on this mixture of fuel and purge fluid, if possible, so as to clean the fuel system of that engine. However, if the fuel and purge fluid mixture is too rich in purge fluid the engine may not start. Also, if the content of purge fluid is too low then the fuel system will not be cleaned effectively. As such, existing fuel system purge methods and apparatus require compromise at some level in their operation.

The fuel system purge method and apparatus of the present invention have as one object thereof to overcome substantially the problems associated with the prior art noted above, or to at least provide a useful alternative thereto.

The preceding discussion of the background art is intended to facilitate an understanding of the present invention only. It should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was part of the common general knowledge in Australia or any other country or region as at the priority date of the application.

Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Disclosure of the Invention

In accordance with the present invention there is provided a fuel system purge method for a diesel engine, the method characterised by the method steps of:

(a) starting the engine with a fuel mix that is predominantly diesel fuel;

(b) introducing a purge fluid into the fuel and allowing the engine to continue running; and

(c) increasing the ratio of purge fluid to fuel whilst the engine is running so as to maximise the cleaning effect of the purge fluid.

Preferably, the ratio of purge fluid to fuel is increased in step (c) to a ratio of about 1 :1.

In accordance with the present invention there is further provided a fuel system purge apparatus comprising at least three reservoirs, each reservoir being

provided with a valve by which the content of the reservoir may be fed to a common outlet line.

Preferably, one of the reservoirs is provided with an inlet or return line feeding thereinto. The return line may have provided therein a filter means.

Preferably, the outlet line is provided with a pump means.

Still preferably, a first reservoir has provided therein diesel fuel, a second reservoir has provided therein a purge fluid, whilst a third reservoir is arranged to receive return fuel or fuel/purge fluid mixture from an engine to which the apparatus may be connected.

Preferably, the outlet line of the fuel system purge apparatus is connected to the fuel line of the engine to be purged between the fuel filter and fuel pump. The return line is preferably connected to the fuel line before the fuel tank. Still preferably, the return line is connected to the fuel line on the end of the injector rail.

Brief Description of the Drawings

The present invention will now be described, by way of example only, with reference to one embodiment thereof and the accompanying drawings, in which:-

Figure 1 is a diagrammatic representation of the fuel system purge method and apparatus of the present invention.

Best Mode(s) for Carrying Out the Invention

In Figure 1 there is shown a fuel system purge apparatus 10 connected to a fuel system 12. The fuel system purge apparatus 10 comprises a first reservoir 14, a second reservoir 16 and a third reservoir 18. Each reservoir 14, 16 and 18 feeds by way of a respective feed line 20, 22 and 24, into an outlet line 26.

The outlet line 26 has provided therein a pump means, for example a diaphragm pump 28.

The fuel system purge apparatus 10 further comprises an inlet or return line 30. The return line 30 has provided therein a filter means 32. The return line 30 feeds into the third reservoir 18.

Each of the feed lines 20, 22 and 24 are provided with respective valves 34, 36 and 38. The presence of the valves allows the flow of fluid from the reservoirs 14, 16 and 18 to be controlled into the outlet line 26 by an operator.

In use, the outlet line 26 is connected to the fuel line 40 of the fuel system 12 after a fuel tank 42, it's associated fuel filter (not shown) and before a fuel injection pump 44, as can be seen in Figure 1. The fuel line 40, from the fuel injection pump 44 passes to injection nozzles 46. From the injection nozzles 46

"overflow" fuel would typically return to the fuel tank 42 by way of return fuel line

48. However, in the present invention the return line 30 of the apparatus 10 is connected to the return fuel line 48 as shown in Figure 1.

When it is desired to clean the fuel system 12 of various deposits that may have built up therein, including gums, lacquers, varnishes, wax and carbon, the outlet line 26 and return line 30 are connected, as described above with reference to Figure 1 , to that fuel system 12. The first reservoir 14 is filled with diesel fuel whilst the second reservoir 16 is filled with a purge fluid. An appropriate purge fluid is that sold under the trade name Firepower Purge Fluid. This product is a blend of hydrocarbon based fluids that act to remove harmful deposits from fuel delivery systems.

The third reservoir 18 is arranged to receive return fuel or return fuel/purge fluid mix from the fuel system 12 by way of return line 30.

Prior to starting the engine, clean fuel is circulated through the fuel system 12 to remove any air which might otherwise prevent the engine from starting should it become trapped in the injectors 46 or the fuel pump 44 through the use of the

method and apparatus of the present invention. The engine (not shown in full) associated with the fuel system 12 is first started on fuel from the first reservoir 14 alone so as to ensure that the engine is able to start and run effectively.

When in operation, the mechanically experienced operator will typically observe the third reservoir 18 and determine when it is approximately half full of clean fuel that has been passed through the fuel system 12 and at that point shut the valve 34 feeding fuel from the first reservoir 14 into the outlet line 26, and open valve 36 feeding purge fluid from the second reservoir 16 into the outlet line 26.

The engine is then started and once at operating temperature, typically after about 10 minutes operation, purge fluid from the second reservoir 16 is gradually introduced to the outlet line 26 through operation of the valve 36 in feed line 22. The ratio of purge fluid to fuel is gradually increased to a ratio of about 1 :1. Once the ratio of 1 :1 is reflected in the fluid in the third reservoir 18 the method is operated on the fluid from the third reservoir 18 alone.

It is preferable that the operator listen to the tone of the engine so that the highest ratio of purge fluid to fuel may be utilised as possible as this will maximise the cleaning effect but ensure that the engine does not stop.

Prior art fuel system purge methods and apparatus typically utilise a single reservoir into which a predetermined mixture of purged fluid and fuel is introduced. Such an arrangement does not allow the monitoring of the fuel system purge and the maximising of the ratio of purge fluid to fuel so as to allow the potentiation or maximising of the cleaning operation.

It is understood that some purge fluid will be burnt in the injectors, that carbon will build up behind the injectors and in fuel lines, as will waxes. However, substantially all such contaminants are subsequently removed by the purge method and are "purged" from the fuel system 12. The small particulate matter is burnt and ejected through the exhaust whilst large particulate matter is largely removed by the filter means 32.

The engine is stopped and the valve 38 of the third reservoir 18 is closed. The fuel line 40 from the fuel tank 42 is reconnected and the method of the invention continued with the engine running. The return into the third reservoir 18 is monitored by the operator until that return shows clean fuel in the return fuel line 48.

Once the operator determines that the fuel system purge is complete the engine is simply stopped and the purge method is concluded.

Modifications and variations such as would be apparent to the skilled addressee are considered to fall within the scope of the present invention.