GB2184522A

GB2184522A - Valve

Info

Publication number: GB2184522A
Application number: GB08628038A
Authority: GB
Inventors: Pierre Debrus; Pierre Bouron
Original assignee: Compagnie des Gaz de Petrole Primagaz SA
Current assignee: Compagnie des Gaz de Petrole Primagaz SA
Priority date: 1985-11-29
Filing date: 1986-11-24
Publication date: 1987-06-24
Also published as: NL8603025A; FR2590938A1; FR2590938B1; LU86690A1; ES2003160A6; GB8628038D0; BE905779A; GB2184522B

Abstract

A valve comprises first and second plates, each plate being provided with a port (19) (Fig. 4), 12, the plates being applied together in a face to face relationship, there being means for displacing the plates. relative to each other, to vary the coincidence of the ports (19), 12 with each other; wherein the width, as measured across the port 12 and perpendicularly to the intended direction of displacement, of a section of the port 12 provided in the second plate is less than the width, as measured in the same manner, of both of the two sections adjacent to that section of that port 12. The variation in width of the port in the second plate allows fuel gas to be fed in an optimal manner to an internal combustion engine. The relative displacement between the plates may be rotational or translational. <IMAGE>

Description

SPECIFICATION Avalve This invention relates to a valve and, more particularly but not exclusively, to a valve intended for use in a feed system for a fuel gas, namely liquefied petroleum gas, in the carburettor of an internal combustion engine which usually functions on petrol.

In French Patent No. 8216257 there is disclosed a feed system for a fuel gas of an internal combustion engine, comprising a valve controlied by the accelerator pedal and intended to control the throughputofgas passing from an inletto an outlet opening intothecarburettororunderthe carburettor. The valve essentially comprises a fixed disc equipped with a port, and a rotatable disc applied face-to-face with respect to the fixed disc and equipped with an elongate port with a width which varies along the length ofthe port. By turning the rotatable disc in relation to the fixed disc, the ports are made to coincide to a greater or lesser degree.

The port of the rotatable disc of the known valve has the shape of a tear; its width increases progressively from one end to the other, in such a way that, in use, the degree of coincidence of the ports increases linearly as the rotatable disc is rotated by depressing the accelerator pedal.

It has now been discovered that this linear growth ofthe degree of coincidence of the two ports does not correspond to optimal feed conditions.

Surprisingly, the degree of coincidence must increase sometimes in a non-linearway, depending on the low pressure which exists downstream of the valve.

According to one aspect of the present invention, there is provided a valve comprising first and second plates, each plate being provided with a port, the plates being applied together in a face to face relationship, there being means for displacing the plates, relative to each other, to vary the coincidence of the ports with each other; wherein the width, as measured across the port and perpendicularly to the intended direction of displacement, of a section of the port provided in the second plate is less than the width, as measured in the same manner, of both of the two sections adjacent to that section of that port.

The valve ofthe present invention can allow an internal combustion engine to be fed in an optimal way with fuel gas.

Preferably one of the first and second plates is fixed.

Preferably the first plate is fixed.

The contour of the port of the second plate depends on each type of engine. Preferably the contourissuch thatthewidths of morethan one section ofthe port provided in the second plate are less than those of the sections which are adjacentto them respectively.

For certain engines, it has been proved to be preferable that the widths ofthe two end sections of the port provided in the second plate are both less than the width of any other section of that port.

From the point of view of the flow of the fluids, it is preferable that an imaginary line, parallel to the intended direction of displacement, divides the port provided in the second plate into two parts having areaswhicharenoticeablyequal,orsimilar,orof mirror-imageform.

The theoretical contours of the port of the second plate, such as they are taken from the testing bench, would lead to sections, expressed as ridges and hollows, of a length, as measured generally along the intended direction of displacement, less than 1 mm and having a ratio of the height to the length of more than approximately 10:1. Besides the fact that the cutting ofthe portwould become difficultforthis reason, or even impossible, these narrow peaks are not compatible with good flow ofthe fluid, as they create losses in load which are too great.A length, as measured generally along the intended direction of displacement, is therefore adopted which is preferably greater than 1 mm and a ratio of heightto length which is preferably less than 10:1,whilst smoothing out the contour in such a way asto compensate progressivelyfora reduction or increase in height of adjoining sections.

The contour of the port of the second plate depends on the leading edge of the port ofthefirst plate. The contour is simplified, and the possibility is thus presented of cutting the port of the second plate so asto have an actual contour corresponding more exactly to the theoretical contour, with less smoothing-out, when the port ofthe first plate is partially defined by one edge, and preferablytwo opposite edges, substantially perpendicular to the intended direction of displacement. This is why circular ports are less favoured for the first plate than ports shaped as a rectangle or as part orall of a sector of a circle.

Preferably the portofthefirst plate is partially defined by two edges substantially parallel to the intended direction of displacement, which, by introducing greater symmetry, also simplify the contour of the port of the second plate. The flow of the fluid is better when an imaginary line, which is parallel to the intended direction of displacement, also divides the port ofthe first plate into two parts having areas which are noticeably equal, or similar, or of mirror-image form.

Avalve according to the present invention which is particularly convenient and is precise for control by an accelerattor pedal, is one in which, preferably, the relative displacement between the plates is rotational. However, the valve ofthe present invention is not limited to that having relative rotational displacement between the first and second plates: the relative displacement could, alternatively, be translational, or even a combination of rotational andtranslational.

According to afurtheraspectofthe present invention, there is provided a combination of a valve in accordance with the first-mentioned aspect of the present invention and, in communication therewith, a feed collar having an outlet opening into a passage passing through the collar.

According to a yet further aspect of the present invention, the combination referred to in the immediately,preceding paragraph also includes a carburettor, with the feed collar opening into a duct either in the carburettor or below the carburettor.

Preferablythe feed collar opens into a duct above a manifold.

For a better understanding of the present invention and to show howthe same may be carried into effect, reference will now be made, by way of example,totheaccompanying drawings, in which: Figure lisa perspective view from above of a part of a gas feed system which includesone embodiment of a valve, shown partially cut away, in accordance with thepresentinvention; Figure2shows, on a reduced scale, more ofthe gas feed system of Figure 1; Figure 3 is a view of part of the second plate ofthe valve, looking in a direction perpendiculartothe plane of the plate; Figure 4is a view of the first plate ofthe valve, looking in a direction perpendicularto the plane of the plate; and Figure 5is a view, like that of Figure 3, of a variant ofthe second plate of the valve.

That partofthefeed system represented in Figure 1 comprises a valve having a housing in the form of a closed cylindrical body 1. A conduit 2 for gas leads from a pressure-reducing valve (not shown) to the body 1 where it opens, via a port in a circumferential wall portion, into the body 1. An eccentric outlet stub 4 leaves from one ofthe planar end walls 3 ofthe body 1. The end of a conduit 5 connects with the outlet stub 4. At the other end of the conduit there is a feed collar 6 with a venturi 7 which is preferably annularand is preferably interchangeable.

Asecond plate 11 equipped with a port 12, is integral with a bearing shaft 13 with a return spring 18 and can rotate in the interior of the body 1 whilst being applied face to face to theinnerwall ofthefirst plate 3 constituted by the aforementioned one planar end wall of the body 1. During the rotation ofthe second plate 1 1,the port 12 variably coincides with a first port 19 arranged in the first plate 3 and circumscribed in the circumference of the outlet stub 4.The bearing shaft 13 passes through the other planar end wall 1 4which is opposite the first plate 3, and, outside the body 1 ,the bearing shaft 13 is fixed for rotation with one ofthe ends of a first connecting rod 15, the other end ofwhich carries a pivotally mounted coupling socket 16which is attached to one ofthe ends ofa cable 17.

When the accelerator pedal is depressed, the second plate 11 rotates by means ofthe linkage 1 stro 17 and 21 to 23 (shown in Figure 2) and the coincidence ofthe second port 12 and the first port 19 is thus varied. When the pedal is released, the return spring 18 moves the second plate back to its original position.

The device represented in Figure 2 shows howthe collar6 is secured between the shoulder 8 ofthe carburettor9andtheinletmanifold 10 ofthe engine, and howthe cable 17 is mounted on the carburettor control mechanism 21 by means of a second connecting rod 22 and a pivot 23. The second connecting rod 22 is moved by a cable linked to the accelerator pedal (not shown).

In Figure 3 sections ofthe second port 12 are arbitrarily defined by discontinuous radial lines on the plate. Section 24, defined by the radial lines 25 and 26, has a minimum width, as measured across the port in the radial direction, which is less than that of an adjacent section 27 defined by the radial lines 25 and 28, and that ofthe other adjacent section 29, defined by the radial lines 26 and 30. Similarly a section 31, defined by the radial lines 32 and 33, has a minimum width less than that of an adjacent section 34, defined by the radial lines 33 and 35, and also less than that ofthe other adjacent 36, defined bythe radial lines 32 and 27.

The two end sections 38,39 are each of a width which is less than that of any other section of the port 12.

An imaginary arc of a circle 40 divides the port 12 intotwo parts namely an outer part41 and an inner part 42, having noticeably equal areas.

The port 19 cut out ofthe first plate 3 represented in Figure 4 is shaped as part of a sector of a circle being defined by two opposite edges 45,46 extending along radial directions and two opposite edges 43,44 shaped as arcs of a circle, concentricto the circumference of the plate 3. An imaginary arc of a circle 40 divides the port 19 into two parts 47,48 of noticeably equal areas.

Figure 5 illustrates a variant of a second plate 11 equipped with a port 12 adapted for use in conjunction with a carburettor with two bodies.

Figure 5 shows two sections 49,50 which are of less width than their respective pairs of adjacent sections, namely 51,52 and 52,53.

Claims

1. Avalve comprising first and second plates, each plate being provided with a port, the plates being applied together in a face to face relationship, there being meansfor displacing the plates, relative to each other,tovarythecoincidenceoftheports with each other; wherein the width, as measured across the port and perpendicularly to the intended direction of displacement, of a section of the port provided in the second plate is less than the width, as measured in the same manner, of both ofthetwo sections adjacent to that section of that port.

2. A valve according to Claim 1,wherein one of the first and second plates is fixed.

3. Avalve according to Claim 2, wherein thefirst plate is fixed.

4. Avalve according to Claim 1,2 or 3, wherein the widths of more than one section of the port provided in the second plate are less than those of the sections which are adjacenttothem respectively.

5. Avalve according to any preceding claim, whereinthewidthsofthetwo end sections ofthe port provided in the second plate are both less than the width of any other section of that port.

6. A valve according to any preceding claim, wherein an imaginary line, parallel to the intended direction of displacement, divides the port provided in the second plate into two parts having areas which are noticeably equal, or similar, orof mirror-image form.

7. Avalve according to any preceding claim, wherein each ridge or hollow ofthe contour defining the port of the second plate has a length, as measured generally along the intended direction of displacement, which is greaterthan 1 mm.

8. Avalve according to any preceding claim, wherein the ratio of height two length of each ridge or hollow of the contour defining the port provided in thesecond plate is less than 10:1.

9. Avalveaccordingtoanyprecedingclaim, wherein the port provided in the first plate is partially defined by one edge which is substantially perpendicularto the intended direction of displacement.

10. Avalve according to Claim 9, wherein the port provided in the first plate is partially defined by two opposite edges substantially perpendicularto the intended direction of displacement.

11. Avalve according to Claim 9 or 10, wherein the port provided in the first plate is also partially defined by two edges substantially parallel to the intended direction of displacement.

12. Avalve according to any preceding claim, wherein an imaginary line, parallel to the direction of intended displacement, divides the port provided in the first plate into two parts having areas which are noticeably equal, similar or of mirror-imageform.

13. Avalve according to any preceding claim, wherein the relative displacement between the plates is rotational.

14. A valve according to any preceding claim, wherein the relative displacement between the plates is translational.

15. A valve according to Claim 1, of which the first or second plate is substantially as hereinbefore described with reference to, and as shown in, Figure 3 or Figure 5 ofthe accompanying drawings.

16. The combination of a valve according to any preceding claim and, in communication therewith, a feed collar having an outlet opening into a passage passing through the collar.

17. The combination according to Claim 16, substantially as hereinbeforedescribedwith reference to, and as shown in, Figure 1 ofthe accompanying drawings.

18. The combination according to Claim 16, which also includes a carburettor, with the feed collar opening into a duct either in the carburettor or below the carburettor.

19. The combination according to Claim 18, wherein the feed collar opens into a duct above a manifold.

20. The combination according to Claim 19, substantially as herein before described with reference to, and as shown in, Figure 2 ofthe accompanying drawings.