GB2185071A - An air intake for an i.c. engine - Google Patents

Abstract

An air intake comprises a plastics hollow body 1 having a continuous outer wall defining an inner cavity 2 for the air, the wall having an inlet 3 for air coming from an air filter and an outlet 4 for air to a mixture-forming device 6, e.g. a carburettor. Pins 31 captive in the body 1 by abutment between resilient sleeves 38 gripping the pins and pin shoulders 40 provide connecting means to the device 6 which cannot be accidentally separated from the body. A flame trap grille 25 is arranged downstream of the inlet 3 and a silencing chamber 20 communicates through a tube 21 with the cavity 2. A plate 41 fixed to the body 1 around the outlet 4 has holes (42, Figure 4) which locate over screws projecting from the device 6 and threaded bores (34, Figure 5) in the pins 31 are engaged with the projecting screws to secure the body to the device. <IMAGE>

Description

SPECIFICATION An air intake for a fuel-and-air mixture-forming device of an internal combustion engine, in particular for a carburettor The present invention relates to an air intake for a fuel-and-air mixture-forming device for an internal combustion engine, in particular for a carburettor, which is interposed between an air induction opening of the said device and a filtered air outlet duct of an airfilter.

Filters utilised in association with an air intake of the type such as that to which that of the present invention relates normally comprise a casing in which is disposed a filtering element provided with an air inlet aperture and an airductableto connectthiscasing with the air intake which is fixed directly to a plate of the mixture-forming device.

Air intakes of the type indicated substantially comprise a body of approximately cylindrical form which has an aperture in its lowerwall for outlet of the air towards the mixture-forming device and another aperture in its upperwall closed by a cover; the lateral wall is shaped in such a way as to give rise to a sleeve which can be connected to the said filtered air outletductfrom the airfilter.

At its edgethe air outlet aperture is formed with a plurality ofholeswhich allowthefixing ofthe air intake to the plate ofthe mixture-forming device; the connection between the air intake and the plate is achieved by means of screws inserted in such holes and screwed into corresponding threaded holes in the plate itself. To perform such operations, which take place on the motorvehicle assembly line, it is necessaryto separate the coverfromthebody,to dispose this in the correct position overthe plate of the mixture-forming device and, subsequently, to introduce into the cavity of the body itself, passing through the aperture formed in the upperwall thereof, fixing screws which must be subsequently screwed by utilising special tools.

Air intakes of the type briefly described have var ious disadvantages.

First of all,they are constructionally rathercom- plex and therefore expensive: in fact, they include, as well as the first defined body, the cover which is able to close the upper aperture thereof, as well as a sealing element interposed between the cover and the body and suitable threaded connection members, for example, bolts. Moreover, the operations necessaryfor assembly of the air intake onto the mixtureforming device in assembly lines are long, require particular ability and the utilisation of special tools; it is in fact necessary, as has been indicated above, to dismantle the cover from the body to gain access to the cavity of the body itself and to the interiorthereof to introduce and manoeuvre the screws for fixing the air intake to the plate of the mixture-forming device.

The object of the present invention is that of providing an air intakefor a fuel-and-air mixture-forming device for an internal combustion engine of the type first indicated, which will be free from the disadvantages which have been described and, therefore, will be constructionally very simple and of low cost, and which can be mounted on the mixture-forming device in a simple and rapid mannerwithout dismantling any parts ofthe air intake itself and without the use of tools of special type.

This and other objects are achieued by means of an air intake for a fuel-and-air mixture-forming device of an internal combustion engine, in particularfora carburettor, which is interposed between an air induction opening of the said device panda filtered airout let duct from an airfilter, characterised by the fact that it comprises a hollow body provided with a continuous external wall defining an inner cavity forthe air, the said wall having only two individual apertures one of which isforthe inlet of air coming from the said duct and the otherforthe outlet of air, which is in communication with the said air induction opening ofthe said device, and connection means for connecting the said hollow body to the said mixtureforming device which can be actuatedfrom the outside of the body and are not accidentally separabie from the body.

For a better understanding of the present invention there is now given, byway of example, a more detailed description of a particular embodiment thereof shown in the Figures of the attached drawings, in which: Figure lisa plan view of the air intake of the invention; Figure2 shows a longitudinal section thereof taken on the line ll-ll; Figure3 is another section ofthq air intake of Figure 1 taken on the linelll-lll; Figure 4 is a plan view from above of one ofthe half-shells which constitute the body of the air intake of the invention; Figure 5is a partially sectioned side view of a threaded pin which forms of the means for connect- ing the air intake to thefuel-and-air mixture-forming device.

The air intake of the invention can be fitted between an air induction opening of a fuel-and-air mixture-forming device of an internal combustion engine, such as a carburettor or a device of this type provided with a fuel injector, and the filtered air output duct of an air filter oftype comprising a casing in which is disposed a filtering element traversed by the air flow.

The air intake of the invention substantiallycomprises a hollow body, generally indicated 1, which is provided with a continuous outerwall defining an in ner cavity forthe air; the said outer wal I has only two individual apertures, one of which is indicated 3 forthe ingress of aircoming from the fiitered airout- let duct and the other, indicated 4, which can be put into communication with an air induction opening 5 of the fuel-and-air mixtu re-formi ng device ofwhich onlythe attachment plate 6 is visible in Figure 1 ;;the body 1 substantially comprises a substantially flat upperwall portion 7, and a lower wall portion 8 which is also substantially flat, and in which is formedtheairoutletaperture4,anda lateralwall portion 9 which connects the other two wall portions and which is shaped in the form of a sleeve 10 the mouth of which constitutes the air inlet aperture 3.

Conveniently, the upper wall portion 7 has a spher ical region 15 disposed substantially over the air outlet aperture 4formed in the lowerwall portion 8.

The body 1 is conveniently constituted by two half shells,namelya lower half-shell 16and an upper half-shell 17, made of plastics material and joined together along a junction plane which cuts the side wall portion 9 and which is substantially parallel to the upperand lowerwalls7and 8; the connection of these half-shells can be effected in any convenient manner, for example by means of hot knife welding processes.

The body 1 can be provided with a substantially cylindrical wall 19 able to define a second cavity 20 within the interior of the body itself, in communication with the preceding cavity by means of a sleeve 21 projecting from the wall itself.

Conveniently, on the lower wall portion 8 in cor respondence with the aperture 4there is provided an annular ring 22 which can rest on the attachment plate 6. Moreover, this body can include a pair oftongues 23 and guides 24ableto support a flame tramp grille 25. The body itself can then be provided with an elbowoutlet30 in communication with thesleevelO and provided for the collection of oil vapours.

The air intake of the invention includes connection means able to connect the intake itself to the plate 6 ofthe mixture-forming device. Such means substantially comprise a plurality, for example three, threaded pins 31, each of which is provided with an actuating head 32 and can be introduced into a corresponding hole33formed in the upperwail portion 7, and screwed onto a corresponding threaded part rigidly connected to the plate 6 ofthe mixtureforming device; the end part of each pin 31 can be provided with a threaded hole 34 which can receive the threaded shank of a captive screw in the plate 6 (not shown).

The head 32 of each pin 31 is housed in a corresponding cylindrical seat 35 formed in the upper wall portion 7, and within this seat, there is disposed an annular seal 36 and between this and the head there is interposed a washer 37. Beneath the seat 35 there is formed a resilient sleeve 38, the inner surface of which can exert a pre-determined pressure on the outer surface of the pin 31; to this end, to increase the resilience ofthesleeve itself, this can be provided with one or more longitudinal slots 39.

The pin 31 is provided with a step 40 arranged to constitute an abutment shoulder againstthe end of the corresponding sleeve 38.

The length of each of the pins 31 is such that it allows the end of each of these to rest substantially on the lowerwall portion 8 close to the edge of the air outletaperture4. Between each end and this wall portion there is interposed an annular plate 41, provided with holes 42 in which the captive screws carried by the plate 6 become inserted. This plate is con venientlyfixed to the lower wall portion 8 by means ofthe material oftongues43 bent, by plastic deformation, over the plate itself.

Assembly and use of the air intake of the invention is as follows.

First of all, an assembly is prepared comprising the hollow body 1 and the threaded pins 31 mounted on it in the manner indicated in Figure 3, in which each of these pins is located within a cavity 2 of the body and the associated head 32 is lodged in the corresponding seat 35 over the seal 36 and the washer 37. In this configuration each of the pins is retained in position by friction which each sleeve 38 exerts on the side surface thereof; accidental dismantling of a pin from the body is prevented by the action of the shoulder 40 which, by interfering with the end ofthe sleeve 38 constitutes an abutment stop against movement of the pin itself.

The assembly thus obtained can be stored and utilised directly on the assembly line of the motor vehicle on which they are to be mounted; to perform such operations it is sufficientto bring the air intake into the correct position with respect to the plate 6, interposing a sealing ring 44 (Figure 2) between this and the annular ring 22 of the body itself; since this plate is already provided with captive screws, these are inserted into the holes 42 of the plate 41 causing a slight raising of the pins 31 with respect to the hollow body 1. Subsequently, by acting with a suitable key on the pins 31 these are screwed onto the corresponding captive screws; at the end of this screwing the end surface of each pin 31 exerts on the plate 41 a sufficiently high force to lock the air intake stably with respect to the plate 6.The plate 41 has the purpose oftransmitting substantially uniform locking pressures to the annular ring 22. Atthe end of this locking operation the heads 32, by compressing the associated seals 36, generate an effective sealing action abieto prevent the escape of air from the cavity2 in the hollow body 1. It is therefore, evident that with the air intake ofthe invention the assembly operation ofthis onto the fuel-and-air mixture-forming device can be effected in a simple and rapid mannerwithout the use of special tools; moreover the air intake can be constructed and stored with associated fixing means and these latter cannot be accidentally separated from the air intake itself.

During operation the air which enters through the inlet aperture 3 flows towards the air outlet aperture 4to the interior of the mixture-forming device, whilst the second cavity 20 performs, in a known way, a silencing action on the movement of the air which flows within the intake.

It is evident that the air intake of the present invention can have modifications and variations, both as to form and to arrangement of the various parts, introduced thereto without departing from the ambit ofthe invention itself. In particular, the closed body 1 can have a different form from that which has been indicated and may, for example, not be provided with the second, silencing cavity 20. Moreover, the number and position of the threaded pins 31 can also be different; similarly, this air intake can be provided with other accessory parts and some of those which have been indicated may be omitted.

Claims (12)

1. An air intake for a fuel-and-air mixture-forming device of an internal combustion engine, in part icularfor a carburettor, which is interposed between an air induction opening ofthe said device and a filtered air outlet of an airfilter, characterised in that it comprises a hollow body having a continuous outer wall defining an innercavityforthe air, the said wall having onlytwo individual apertures, one forthe inlet of air coming from the said duct and the other forthe outlet of air, which is in communication with the said air induction opening ofthe said device, and connection meansforconnecting the said hollow body to the said m ixtu re-form ing device, which can be actuated from the outside of the body and not ac cidentallyseparablefromthe body.

2. An air intake according to Claim 1,characterized in that the said hollow body includes a sub stantiallyflatupperwall portion and a substantially flatlowerwall portion, parallel tothe preceding wall portion, and in which the said air outlet aperture is formed, and a side wall portion which connects the othertwowall portions and which is shaped to form a sleeve the mouth of which constitutes the said air inlet aperture.

3. An air intake according to Claim 2, characterised by the fact that the said upper wall portion has a spherical region disposed above the said air outlet aperture formed in the said upperwall portion.

4. An air intake according to one of Claims from 1 to 3, characterised by the fact that the said hollow body is constituted by two half-shells made of plastics material and joined together along a junction plane which cuts through the said side wall portion and which is parallel to the said upper and lower wall portions.

5. An air intake according to any preceding Claim, characterised in that the said connection means include threaded pins each of which is provided with an actuating head and can be inserted into a corresponding holeformed in the said upperwall portion and screwed into a corresponding threaded part fixed to the said m ixtu re-forming device, the said head being ableto rest on the said upperwall portion and the said pin being provided with a shoulderwhich can exert predetermined pressures on the said lowerwall portion after it has been screwed onto the said threaded part for locking it to the said mixture-forming device.

6. An air intake accordipg to Claim 5, characterised in that the said connection means further include a small plate of annularform which can be positioned over the edge region of the said air outlet aperture of the said lowerwall portion, the said shoulder resting on the said annular plate.

7. An air intake according to Claim 6, characterised in that each of the said threaded pins has a threaded end hole and the said threaded part fixed to the said mixture-forming device is constituted buy a screw threaded shank on a plate of the said device, the said annular plate being provided with holes on the edges of which the ends of a corresponding threaded pin rest.

8. An air intake according to Claim 7, char acterised in thatthe said annular plate isfixed tothe said lowerwall portion by plastically deforming over it the material of at least one tongue of the said lower wall portion.

9. An air intake according to any ofthe preceding Claims, characterised in that it includes seal means interposed between each ofthe said threaded pins and the said upperwall portionforsealing aircontained in the said cavity, the said sealing means including a cylindrical seatforthesaid head ofthesaid threadedpinformedonthesaid upperwall portion, an annular seal fitted in the said seat and a washer interposed between the seal and the head.

10. An air intake according to any preceding Claim, characterised in that it includes means for preventing the accidental separation of the said threa- ded pins from the said body, the said means including radially deformable sleeves each of which is formed beneath one of the said seats, capable of exerting radial pressure on a corresponding threaded pin, and annular shoulders formed on the said pins each of which is ableto cooperate with an associated sleeve to stop axial displacement of the pin.

11. An air intake according to Claim 10, characterised by the fact that each of the said sleeves has at least one axial slot for making it resiliently deformable.

12. An air intakefor a fuel-and-air mixtureforming device of an internal combustion engine, substantially as described and illustrated in the attached drawings.