GB2062091A

GB2062091A - Water/Fuel Emulsion Carburettor Systems

Info

Publication number: GB2062091A
Application number: GB7938532A
Authority: GB
Original assignee: Dynatrol Consultants UK Ltd
Current assignee: Dynatrol Consultants UK Ltd
Priority date: 1979-11-07
Filing date: 1979-11-07
Publication date: 1981-05-20
Also published as: GB2062091B

Abstract

A method of supplying fuel to an internal combustion engine comprising adding water via line 122 to the fuel and continuously circulating the contents of the float bowl (111), the circulation involving subjecting the mixture to mixing for example in an emulsifier (120). <IMAGE>

Description

SPECIFICATION Carburettor Systems The present invention relates to carburettor systems for petrol fuelled spark ignition internal combustion engines.

In our published German OLS No. 2,655,901, we have described the use of an emulsifier forming the subject of that specification to feed a mixture of petrol and water to a bowl and float carburettor.

The engine worked very satisfactorily with reduced fumes and noise.

We have now discovered that by continuously recirculating the contents of the bowl of a bowl and float carburettor substantial fuel savings may be achieved over a range of water to petrol ratios at a variety of engine speeds and loads, moreover this can be achieved without significant loss of engine power within certain ranges of water to petrol ratio and that reductions in exhaust emissions of oxides of nitrogen can also be achieved without significant change in carbon monoxide, hydrocarbon or smoke emissions with variation in water to petrol ratios.

Thus according to the present invention a method of supplying fuel to an internal combustion engine comprises continuously circulating the contents of the bowl of a bowl and float carburettor, and adding water thereto in the absence of any surfactant, the circulation involving subjecting the mixture to mixing, whereby the water petrol mixture is maintained as a dispersion in the bowl of the carburettor and is aspirated as a dispersion into the engine.

Preferably the mixing produces an intimate mixture and this may be achieved by intensive mixing e.g. using a high speed rotor e.g. rotating at 2500 to 5000 rpm.

The mixing is preferably carried out at a location remote from the bowl.

The recirculation flow rate through the mixing zone is preferably at least 5%, e.g. at least 10% or, at least 20% especially at least 50% of the flow rate of the mixture out of the carburettor.

The water is preferably added to the mixture whilst the mixture is being subjected to the mixing.

In a preferred form of the invention, petrol is fed to the carburettor through the inlet needle valve, the fuel is circulated from the lower, preferably the lowest, region of the bowl to a mixing region where water is metered into the fuel and the mixture mixed and circulated back to the bowl, preferably to a location below the normal fuel level in the bowl.

Preferably the mixing involves a pumping action sufficient to maintain the continuous recirculation without any additional pumping action being applied to the mixture.

The invention extends to a fuel supply system including a bowl and float carburettor having an outlet and an inlet in the bowl, the outlet being connected to the inlet to a mixing device and the inlet being connected to the outlet of the mixing device, a water inlet connected to the feed line from the bowl to the mixing device or directly to the inlet side of the mixing device, the mixing device being such as to achieve continuous recirculation of the mixed fuel through the bowl of the carburettor.

A preferred form of mixing device consists of the emulsifier shown in our above German OLS modified so as to increase its pumping action to significant levels, e.g., by widening the throat in the ducts through the rotor.

Thus in a preferred form of the invention the mixing device consists of apparatus for mixing fluids comprising a housing affording a substantially annular mixing chamber, an annular rotor mounted for rotation in the mixing chamber, outwardly extending individual enclosed passages being located in the rotor, the inlet orifices to the passages in the rotor being disposed at or adjacent its axis of rotation, the enclosed passages in the rotor leading from the said inlet orifices to the periphery of the rotor and emerging therethrough, an inlet chamber communicating with the inlet orifices in the rotor and disposed at or adjacent the axis of rotation of the rotor, the inlet chamber being provided with inlet means for the fluids to be mixed, the mixing chamber having a circular outer wall extending around a major proportion of its circumference with a small clearance between the said circular wall and the periphery of the rotor, the circular outer wall extending outwardly into a spiral shape so as to define a generally crescent shaped outlet region between the spiral shaped wall of the mixing chamber and the periphery of the rotor, the outlet region communicating with an outlet passage and drive means arranged to enable the rotor to be rotated in the mixing chamber.

The rotor is preferably provided with a multiplicity of individual outwardly extending enclosed passages leading from the inlet orifices of the rotor to outlets in the peripheral surface of the rotor and emerging therethrough, the individual passages extending out through the peripheral surface of the rotor and being spaced from each other by solid regions of the peripheral surface, the ratio of the radial distance from the inlet to each passage to the outer surface of the rotor to the radius of the rotor being in the range of 0.4:1 to 0.9:1.

The ratio of the radius of the rotor to the clearance between the periphery of the rotor and the circular portion of the outer wall of the mixing chamber is preferably at least 200:1.

The radial passages preferably have at least one constriction intermediate their ends. In one preferred form of the invention, 6 to 20 radial passages are provided. In one form of suitable mixing device each radial passage preferably has a convergent entry portion leading to the constriction and a divergent outlet portion.

A specific embodiment of mixing device preferred for use in the invention comprises a housing affording a substantially annular mixing chamber, an annular rotor mounted for rotation in the mixing chamber, outwardly extending enclosed radial passages being located in the rotor, the enclosed radial passages each comprising a V-shaped convergent inlet end, a Vshaped divergent outlet end, and a parallel sided throat portion interconnecting the V-shaped inlet end and the V-shaped outlet end of each enclosed radial passage, the inlet orifices to the passages in the rotor being disposed at or adjacent its axis of rotation, the enclosed passages leading from the inlet orifices to the periphery of the rotor and emerging therethrough, an inlet chamber communicating with the inlet orifices in the rotor and disposed at or adjacent the axis of rotation of the rotor, the inlet chamber being provided with inlet means for the fluids to be mixed, a circular outer wall extending around a major portion of the circumference of the mixing chamber with a small clearance between the circular outer wall and the periphery of the rotor, the circular outer wall extending outwardly into a spiral shape so as to define a generally crescent shaped outlet region between the spiral shaped wall of the mixing chamber and the periphery of the rotor, an outlet passage communicating with the outlet region and, drive means connected to the rotor so as to rotate in the mixing chamber.

The radial length of each passage is preferably 0.6 times the radius of the rotor. The V-shaped inlet end preferably forms an included angle of 40 to 80 and the V-shaped outlet end forms an included angle of 10 to 40 .

The invention may be put into practice in various ways and one specific embodiment thereof will be described by way of example to illustrate the invention with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic view of a carburettor fuel system in accordance with the present invention for a spark ignition petrol engine, Figure 2 is a longitudinal cross section of a preferred embodiment of an emulsifier on a much enlarged scale compared to Figure 1 for use in the system shown in Figure 1, Figure 3 is a cross section on the line Ill-Ill of Figure 2, on a reduced scale, showing the mixing chamber and, diagrammatically, the outline of the rotor, and Figure 4 is a cross section on the line IV--IV of Figure 2, on an enlarged scale showing in detail the shape of the passages in the rotor.

Figure 1 shows diagrammatically a carburettor fuel system in accordance with the present invention for a spark ignition petrol engine.

The system has a down draft manifold 100 having an air inlet 101, a venturi 102 and a fuel inlet 103 and leads to the engine inlet manifold as indicated by the arrow 104.

The fuel inlet 103 in accordance with the invention is fed with a dispersion of water in petrol from a float carburettor 105 via the outlet pipe 106 of the carburettor.

The carburettor has a conventional petrol inlet needle valve 107 controlled by a float 108 which is mounted on a pivot 109 so that as the fuel level, indicated at 110, in the float chamber 111 drops, the valve 107 opens and vice versa. The needle valve 107 is fed by a petrol supply pipe 112.

So far the arrangement is conventional and the exact form of carburettor and fuel level control mechanism is not critical.

In accordance with the invention the float chamber 111 has an inlet 115 and an outlet 116 located below the normal range of levels of the fuel level 110. The inlet 115 is fed via a line 117 from the output 11 8 of a mixing device 120 and the output 11 6 feeds the input 121 of the mixing device via a line 124.

The mixing device also has a preferably metered supply of water to its input side via a valved line 122 controlled by a needle valve 123.

The device 120 is driven by a motor 125, e.g., an electric motor or other drive means and is selected to both prevent the water from separating from the petrol, e.g., by producing a very fine dispersion of water in petrol, which is preferably an emulsion, and to recirculate the contents of the float chamber 111 by acting as a pump without causing the water to separate from the petrol.

Figures 2 to 4 show the preferred form of mixing device which we use in accordance with a preferred aspect of the present invention as the mixing device 120 in Figure 1.

The emulsifier is connected to the line 122 by its inlet port 51 and to the line 124 by its inlet port 52 (see Figure 2).

The output of the emulsifier is connected to the line 117 by its outlet port 65 (see Figure 3).

The emulsifier shown in Figures 2 to 4 consists of an inlet chamber housing 10 and a seal housing 11 bolted together by bolts 12 and provided with an '0' ring seal 13. The housings 10 and 11 between them provide a mixing chamber 1 5. Located in the mixing chamber for free rotation therein is a rotor 20 having radial passages 19, the rotor being supported on a shouldered drive shaft 21 which extends out through an aperture 23 to an external drive 25 (not shown).

Interposed between the rotor 20 and the aperture 23 is a mechanical seal of conventional type, the aperture 23 being part of the seal. The seal is located within a seal chamber 35 formed in the seal housing11. The seal chamber 35 is separated from the mixing chamber 1 5 by the rotor 20 except for a small clearance C, between the outer edge of the rotor and the inner peripheral wall 37 of the mixing chamber 15.

Liquids are prevented from passing directly through into the chamber 35 by the provision of a recirculation flow of the emulsion which is introduced through an orifice 40 (not shown) into the seal housing 11 and which provides a cooling effect for the seal and then recombines with the emulsion in the chamber 15. The housing 10 provides an inlet chamber 50 which is fed by a water inlet passage 51 and a fuel inlet passage 52. The inlet chamber comprises the substantially cylindrical chamber 53 at the confluence of the passages 51 and 52, plus the disc shaped chamber 49 located between the central end face 54 of the rotor 20, the inlet wall 55 of the passages 1 9 and the end face 56 of the chamber 53.

The mixing chamber 1 5 is defined as being bounded by a front wall 60, an inner wall extending from the inside edge of the front wall parallel to the longitudinal axis of the device, an outer side wall, of which part 37 is circular and part 66 is spiral, and a rear wall extending parallel to the front wall 60 from the rear of the outer side wall. The mixing chamber communicates with an outlet passage 65 disposed tangentially to the rotor (see Figure 2) and transverse to its axis.

The circular wall 37 extends around the chamber for 2400 and the spiral wall 66 extends outwardly from the point 70 to the outer edge of the outlet passage 65. The mixture chamber includes this part crescent shaped region extending from point 70 to the line 72 across the opening 65. The mixing chamber is largely occupied by the rotor 20.

The ratio of the volume of the inlet chamber to the free volume of the mixing chamber, i.e., its volume minus that of the rotor, is preferably in the range 0.8:1 to 1.4:1,e.g.,0.9:1 to 1.3:1, especially about 1.1:1.

The clearance, C, between the wall 37 and the outer space of the rotor is preferably in the range 0.001" (0.00254 cms) to 0.005" (0.0127 cms), e.g., 0.002" (0.00508 cms). The radius R, of the rotor is 2.8" (7.112 cms).

The ratio R/C is preferably at least 200:1 or preferably at least 500:1,e.g., in the range 500:1 to 3000:1, and more particularly by 1000:1 to 2000:1.

The generally crescent shaped region may have a flat outer wall as shown in Figure 2.

However, one convenient way of making this part of the housing is to mill out the cylindrical mixing chamber and drill the circular outlet opening 65 tangentially to the circular chamber down to the point 78. One can then pick out the region 1 5 with a milling machine from a line 72 down to the point 70 so as to smooth out the transition between the hole 65 and the circular wall 37 of the mixing chamber to form the curved region extending from the line 72 to the point 70. In this arrangement, the wall 66 need not be flat. The maximum clearance, C2, between the wall 66 and the periphery of the rotor at the point 78 is many times that of the clearance C between the wall 37 and the rotor and the ratio C2/C is preferably at least 10:1 and more desirably at least 50:1 or 100:1 and particularly in the range 50:1 to 200:1 or 500:1.

Referring now to Figure 3, the rotor 20 in this embodiment has twelve radial passages 19 equally spaced apart through 300 and extending from the inlet wall 55 to the outer periphery 36 of the rotor 20. The radial length of each passage 1 9 is 0.6 times the radius of the rotor.

In this form of the invention the inlet end of each passage is a V-shaped slot 172 including an angle of 600 and the outlet end is a V-shaped slot 73 including an angle of 200: these angles are such that the slots would intersect even if the passage was not broadened in this region to form a parallel sided throat portion 71. The throat portion is circular in cross section and 3/1 6" in diameter (0.10 cms). The ratio of the diameter of the throat to the width of the inlet is 0.625:1.

More broadly, the included angle of the slot 1 72 is greater than that of the slot 73 and can range from 400 to 800 whilst the included angle of the slot 73 can range from 100 to 400.

The ratio of the width of the throat to the width of the inlet may be in the range 0.5:1 to 0.9:1 e.g.

0.6:1 to 0.8:1.

The ratio of the length of the radial passage 1 9 to the radius of the rotor 20 can vary from 0.9:1 to 0.4:1.

The throat or constriction, or if there are multiple throats or constrictions, at least one is desirably located within 10 to 90% e.g., 20 to 80% of the length of the passage 1 9 from its inlet end.

When the passage is provided by a convergent divergent duct the divergent portion is preferably longer than the convergent portions. However, the inlet diameter or width is preferably much the same as the outlet diameter or width e.g., in the range of ratios of 0.8:1 to 1.2:1.

In operation, for example, water can be fed to the emulsifier in amounts ranging up to 30% by weight based on the weight of the petrol. If a pressurised fuel supply is used then the water supply should be pressurised to a similar pressure.

The rotor is driven up to 5000 r.p.m. e.g., at 2800 r.p.m. up to 5000 r.p.m. in a clockwise direction as viewed in Figure 2. The fuel and water mixture is drawn from the inlet chamber by the centrifugal force on the liquid in the passages 1 9 and thrown out radiably through the passages 1 9 and caused to hit the wall 37. The outer wall 36 of the rotor is broken up into twelve solid portions 77, each about twice the circumferential length of the outlets 73, and the solid portions 77 may be considered to act as vanes.

They thus have the function both of shearing the fuel and water mixture in the gap between the wall 37 and the wall 36 and propelling it around the circumference of the mixing chamber through the part crescent shaped region 78, where turbulent mixing may be expected to occur and then ejecting it through the outlet passage 65.

Claims

1. A method of supplying fuel to an internal combustion engine comprising adding water to the fuel and continuously circulating the contents of the bowl of a bowl and float carburettor, the circulation involving subjecting the mixture to mixing.

2. A method as claimed in Claim 1 in which the mixing comprises subjecting the mixture to cavitation and shearing whereby the water petrol mixture is maintained as a dispersion in the bowl of the carburettor and is aspirated as a dispersion into the engine.

3. A method as claimed in Claim 1 or 2 in which the mixing is carried out at a location remote from the bowl.

4. A method as claimed in Claim 1,2 or 3 in which the recirculation flow rate through the mixing zone is at least 5% of the flow rate of the mixture out of the carburettor.

5. A method as claimed in Claim 1, 2, 3 or 4 in which the recirculation flow rate through the mixing zone is at least 50% of the flow rate of the mixture out of the carburettor.

6. A method as claimed in any one of the preceding claims in which the water is added to the mixture whilst the mixture is being subjected to mixing.

7. A method as claimed in any one of the preceding claims in which petrol is fed to the carburettor through the inlet needle valve, the fuel is circulated from a lower or the lowest region of the bowl to a mixing region where water is metered into the fuel and the mixture mixed and circulated back to the bowl.

8. A method as claimed in Claim 7 in which the mixture is circulated back to a location below the normal fuel level in the bowl.

9. A method as claimed in any one of the preceding claims in which the mixing involves a pumping action sufficient to maintain the continuous recirculation without any additional pumping action being applied to the mixture.

10. A fuel supply system including a bowl and float carburettor having an outlet and an inlet in the bowl, the outlet being connected to the inlet to a mixing device and the inlet being connected to the outlet of the mixing device, a water inlet connected to the feed line from the bowl to the mixing device or directly to the inlet side of the mixing device, the mixing device being such as to achieve continuous recirculation of the mixed fuel through the bowl of the carburettor.

11. A fuel supply system as claimed in Claim 10 in which the mixing device consisting of apparatus for mixing fluids comprising a housing affording a substantially annular mixing chamber, an annular rotor mounted for rotation in the mixing chamber, outwardly extending individual enclosed passages being located in the rotor, the inlet orifices to the passages in the rotor being disposed at or adjacent its axis of rotation, the enclosed passages in the rotor leading from the said inlet orifices to the periphery of the rotor and emerging therethrough, an inlet chamber communicating with the inlet orifices in the rotor and disposed at or adjacent the axis of rotation of the rotor, the inlet chamber being provided with infet means for the fluids to be mixed, the mixing chamber having a circular outer wall extending around a major proportion of its circumference with a small clearance between the said circular wall and the periphery of the rotor, the circular outer wall extending outwardly into a spiral shape so as to define a generally crescent shaped outlet region between the spiral shaped wall of the mixing chamber and the periphery of the rotor, the outlet region communicating with an outlet passage and drive means arranged to enable the rotor to be rotated in the mixing chamber.

12. A fuel supply system as claimed in Claim 11 in which the rotor is provided with a multiplicity of individual outwardly extending enclosed passages leading from the inlet orifices of the rotor to outlets in the peripheral surface of the rotor and emerging therethrough, the individual passages extending out through the peripheral surface of the rotor and being spaced from each other by solid regions of the peripheral surface, the ratio of the radial distance from the inlet to each passage to the outer surface of the rotor to the radius of the rotor being in the range of 0.4:1 to 0.9:1.

13. A fuel supply system as claimed in Claim 12 in which the ratio of the radius of the rotor to the clearance between the periphery of the rotor and the circular portion of the outer wall of the mixing chamber is preferably at least 200:1.

14. A fuel supply system as claimed in Claim 11, 12 or 13 in which the radial passages have at least one constriction intermediate their ends.

1 5. A fuel supply system as claimed in any one of Claims 11 to 14 in which there are 6 to 20 radial passages.

1 6. A fuel supply system as claimed in any one of Claims 11 to 1 5 in which each radial passage has a convergent entry portion leading to the constriction and divergent outlet portion.

17. A fuel supply system as claimed in any one of Claims 11 to 1 6 consisting of an emulsifier in which the throat in the ducts through the rotor is widened to increase its pumping action to significant levels.

1 8. A fuel supply system as claimed in any one of Claims 11 to 1 7 in which the enclosed radial passages each comprise a V-shaped convergent inlet end, a V-shaped divergent outlet end, and a parallel sided throat portion interconnecting the V-shaped inlet end and the V-shaped outlet end of each enclosed radial passage.

19. A fuel supply system as claimed in Claim 18 in which the V-shaped inlet end forms an included angle of 40 to 800 and the V-shaped outlet end forms an included angle of 10 to 400.

20. A fuel supply system as claimed in any one of Claims 11 to 1 9 in which the radial length of each passage is 0.6 times the radius of the rotor.

21. A carburettor fuel system substantially as specifically described herein with reference to Figures 1 to 4 of the accompanying drawings.