Manifold, for instance intake manifold for motorcycle engines

Abstract: The manifold (1) comprises a flange (2) and a tube-like elastic part (4) made of elastomeric material, which are connected to one another without using adhesives. The function of mechanical connection of the two components (2, 4) is separate from the function of gas and liquid tightness. The flange (2) and the tube-like elastic part (4) are provided with complementary formations (5, 6) defining a first step-like part (7a, 7b) which ensures stable connection between the two components (2, 4) in conditions of mutual clamping. The same complementary formations then define together a second step-like part (8a, 8b) which confers the necessary preloading on a seal lip (10) of the tube-like part (4) of the manifold. A further step (11) ensures connection of the two components (2, 4) during storage and handing of the manifold.

Description: The present invention relates to intake manifolds according to the preamble of Claim 1. Intake manifolds of this type are currently used as intake manifolds in internal-combustion engines for motorcycles, whether two-stroke engines or four-stroke engines. The said intake manifolds may, on the other hand, be used, for example, also in engines for ultralight aircraft, snowmobiles and water scooters, motors for chain saws, industrial and agricultural engines and motors of various nature, and motors for do-it-yourself and hobby activities. In general, these are single-cylinder motors or ones equipped, in the case of motors with more than one cylinder, with a series of individual intake manifolds. The flange of the manifold, i.e., the rigid part of the manifold, is in general equipped with a series of holes which are used for installing the manifold on the motor or engine, fixing thereto a first end of the tube-like elastic part. The fixing of the intake manifold on the motor or engine is in general obtained using screws. The other end of tube-like elastic part is fixed to the carburettor or to the throttle body. This takes place in general with a connector of the male/female type secured externally with clamps. In some cases, however, a second flange is used equipped with holes for fixing the carburettor or the throttle body to the tube-like elastic part of the intake manifold. Fluid (i.e., liquid and gas) tightness and mechanical resistance to the applied loads are ensured by an adhesive deposited on the flange or flanges that have the function of rendering the flange or flanges completely integral and fluid-tight with the vulcanized elastomer that normally constitutes the tube-like elastic part of the intake manifold. In order to ensure a good adhesion with the elastomer, the surfaces of the flange must therefore be carefully prepared (typically, with a treatment of sand-blasting and degreasing) before application of the adhesive. The types of adhesives used vary according to the materials that make up the flanges and to the type of elastomer. In some cases, two different types of adhesive are used applied on the flanges at different times and after each layer applied has been dried in an oven. The most commonly used elastomers for making the tube-like elastic part of the manifold are the ones based on mixes such as NBR, FPM, ECO, and NBR+PCV and mixtures of the same, as well as in general types of elastomers capable of withstanding the phenomena of ageing in the presence of fuels and lubricants and the variable loads that are applied, namely the weight of the carburettor or of the throttle body and the mechanical vibrations transmitted by the engine or by the movement of the vehicle. At the same time, it must be taken into account that the tube-like elastic part of the manifold made of elastomer must preferably present visco-elastic characteristics such as may be able to dampen the mechanical vibrations transmitted by the engine to the carburettor / throttle body, likewise providing a good thermal insulation between the engine and the carburettor / throttle body . In addition to this, the fact of resorting to an elastomer to obtain the tube-like elastic part of the manifold proves advantageous also as regards the process of manufacture: in this way, it is in fact possible to produce with relative ease the undercut areas present in the elastomer part of the manifold. As regards the flange, instead, the traditional choice is to resort to a metal support made of steel, aluminium alloy, Zn+Al+Mg alloy or brass alloy. An intimate and durable adhesive connection between the flange and the tube-like elastic part of the manifold made of elastomer has up to the present been considered an essential requisite in order to establish and maintain over time the necessary characteristics of gas and liquid tightness and mechanical resistance (also as regards the stresses of a vibrational and/or thermal nature), this considering also the fact that the metal material used to make the flange and the elastomer used to make the tube-like elastic part of the manifold are intrinsically dissimilar from one another from various points of view. This choice is not, however, optimal for the purposes of the process of fabrication of the manifold. In view of the numerous intermediate and preparatory steps (sand-blasting, degreasing, application of adhesive in one or more layers and drying of said layers in the oven, loading of the flanges in the mould for vulcanizing the elastomer) which prove necessary, the process ends up, in fact, becoming rather complex and hence burdensome, and this latter factor has a negative effect on the cost for fabricating the manifold. FR-A-2724419 discloses a manifold according to the preamble of claim 1 including an inlet pipe connected to the IC engine cylinder by a connector which has an elastic element to ensure the link between the cylinder head of the engine and the inlet pipe. The connector is in the form of a collar of elastic material. The collar consists of a primary axial end, which is fitted against the cylinder head and retained by the locking plate and the securing bolts. The secondary end of the connector is fitted in contact with the inlet pipe and is maintained in position by the securing collar, which is produced as part of the inlet pipe. The purpose of the present invention is that of providing an intake manifold the characteristics of which enable the above drawbacks to be overcome. According to the present invention, the above object is achieved thanks to an intake manifold having the characteristics referred to specifically in the annexed claims. Basically, the solution according to the invention envisages producing the manifold as an ensemble of two components produced separately (flange and tube-like elastic part) and subsequently joined together mechanically in the absence of any adhesive connection. The expression "in the absence of any adhesive connection", as this is used in the present description and, where required, in the annexed claims, refers in general to the fact that the manifold according to the invention does not envisage the presence of adhesives designed to ensure over time the fluid-tight connection between the flange and the tube-like elastic part. The above expression thus refers to the absence of intimate and continuous adhesive connection created during the manufacture of the manifold and designed to continue in time. The existence of such an intimate and continuous connection may readily be found in solutions according to the prior art if any attempt is made to separate the flange and the tube part that are connected adhesively together: the adhesive connection is so strong that the elastomeric material of the tube-like elastic part breaks before the flange and the tube-like elastic part can be separated even only slightly. Consequently, to be understood as included in the scope of the present invention are also any solutions that might involve (for any number of reasons) the application of layers of material that are able to provide - even in an indirect way - a connection of an adhesive nature between the flange and the tube-like elastic part of the manifold, without this, however, resulting in an effective intimate and continuous adhesive connection between the aforesaid parts in such a way as to ensure fluid tightness and mechanical resistance to loads that are applied to the manifold throughout the working life of the latter. Essentially, the solution according to the invention is based upon the recognition of the fact that it is possible to achieve the same action of fluid-tight mechanical connection traditionally exercised by the adhesive by intervening on the conditions of fit between the two parts of the manifold, in particular separating and entrusting to different parts of the connecting structure: on the one hand, the function of mechanical connection between the two components (flange and tube-like elastic part), and on the other hand, the function of gas and liquid tightness. In the currently preferred embodiment of the invention, the fluid-tight connection between the flange and the tube-like elastic part of the manifold is obtained with parts having profiles of complementary shapes in which the following may in general be distinguished: a first connection region - usually hook-shaped - designed to ensure the stable mechanical connection between the two components, in particular after their installation on an engine; and a second connection region - usually consisting of a shoulder - designed to bestow the necessary preloading on the seal lips of the tube-like elastic part of the manifold that ensures gas and liquid tightness. Preferably, to improve further the stability of the mechanical connection, a preloading of the elastic part is provided, obtained by means of an increase in the thickness of the said elastic part. Even more preferably, a further formation is introduced, which is designed to ensure connection of the two components during storage and handling of the assembled manifold. The flange and the tube-like elastic part of the manifold can then be obtained with processes and distinct production equipment. This approach, which involves mechanical assembly of the tube-like elastic part on the flange, enables a reduction in cost and an improvement in the quality of the product. In particular, it is possible to carry out easily a quality control of a non-destructive type on the piece, whereas in the case of use of adhesives, tests can only be of a destructive type. The reduction in the cost of manufacture is linked to the faster moulding processes, which are carried out on machinery at a lower cost, and to the fact that it is not necessary to prepare the surfaces for the application of adhesives or, indeed, to use adhesives. Furthermore, it is not necessary to store the flanges prepared with the adhesive in a very strict condition of cleanliness in view of a connection by adhesion with the tube-like elastic part. The solution according to the invention is, however, also suited to being adopted for overmoulding of the tube-like elastic part on the previously moulded or pressed flange, using a different process. The solution according to the invention is also suited to being adopted for co-moulding of the tube-like elastic part with the flange made of plastic material; i.e., the two components are moulded, using a single particular piece of production equipment, by means of two successive injections of the two materials making up the flange and the tube-like elastic part, thereby avoiding recourse to an adhesive-bonding connection, and resorting instead to a connection of a purely mechanical nature, obtained by separating the function of gas and liquid tightness from the function of connection aimed at ensuring mechanical resistance to the applied loads. In order to make the flange, it is possible to use a die-cast metal material or (in a particularly advantageous embodiment from the production-cost standpoint) a blanked and/or drawn metal material. As an alternative, it is possible to use for the flange a plastic material, such as a thermoplastic material or else a thermosetting material containing a reinforcement material as filler; for example, this may be a polyamide (e.g., PA66) or a phenolic resin with the addition of reinforcement material, such as glass fibre (e.g., with 30% glass-fibre filler). The tube-like elastic part of the manifold according to the invention can be produced using an elastomer of the type cited previously, or in general using any elastomeric material of the type so far used for making the manifolds in question, or yet again- according to a particularly advantageous alternative from the point of view of reduction in production costs - using a thermoplastic elastomer. The present invention is highly advantageous as regards the use of thermoplastic elastomeric materials, in so far as this type of material presents major and serious problems of adhesion to flanges made of metal materials or plastic materials. In actual fact, so far it has not been possible, nor is it known, to use thermoplastic materials for making the tube-like elastic part of the manifold, basically because there do not exist adhesives capable of ensuring the necessary adhesion between the rigid flange and the tube-like elastic part. The advantages in terms of cost in the use of thermoplastic materials derive above all from very short processing times as compared to thermosetting elastomers (typically, rubber) used prior to the present invention. The invention will now be described purely by way of non-limiting example, with reference to the attached drawings in which: Figure 1 is a view of a manifold according to the invention; Figure 2 is another view of a manifold according to the invention, taken from a viewing point approximately diametrically opposite to the viewing point of Figure 1; Figure 3 is a cross-sectional view taken according to the plane indicated by III-III in Figure 2; Figure 4 reproduces, at an enlarged scale, the part illustrated in Figure 3 indicated by the arrow IV; and Figure 5 is a cross section taken according to the plane indicated by V-V in Figure 1. In the figures of the attached drawings, the reference number 1 designates, as a whole, a manifold, such as an intake manifold, of the type currently used in engines for two-wheeled vehicles, or, in general, in engines of the types listed (purely by way of example) in the introductory part of the present description. The characteristics and modalities of use of manifolds of this type are to be deemed, as a whole, known to the prior art, and hence such as not to require a detailed description herein, also because they are in themselves not relevant for the purposes of understanding and implementing the present invention. In this connection, it will be appreciated that the solution according to the invention may be applied advantageously also to manifolds having characteristics of size, shape and structure that are altogether different from those of the manifold 1 illustrated here purely by way of non-limiting example. Basically, in the case of a manifold such as the manifold 1, two essential parts may be distinguished. The first part consists of a flange-shaped support 2, which has an overall annular development. Normally provided in the flange 2 are openings 3; in the example illustrated here, two openings 3 are present, which are located in positions that are diametrically opposite to one another with respect to the annular development of the flange 2. The openings 3 enable fixing of the flange 2, and of the manifold 1 as a whole, to the body of an engine or motor M (marginally illustrated only in Figure 4) to which the manifold 1 is associated. This is done by means of screws (not illustrated) which pass through the openings 3. The foregoing is according to known criteria, in particular as regards the fact that the flange 2 is located in such a way that it surrounds a corresponding intake opening provided in the body of the engine M. The second part of the manifold 1 consists of a tube-like elastic part 4 (the tube-like conformation is more evident in Figure 5) designed to establish a path of flow of an aeriform substance, typically the air-fuel mixture, to the intake opening made on the engine around which the flange 2 is mounted. The tube-like elastic part 4 has in general a proximal end 4b (the one connected to the flange 2) and a distal end 4a (see Figure 2) for connection of a carburettor or throttle body (not illustrated). Connection of the distal end 4a of the tube-like elastic part 4 to the aforesaid carburettor or throttle body is by means of a connector of the male/female type secured with clamps (not illustrated). As has already been said, it is also possible to associate to the end 4a another flange provided with openings for fixing the carburettor or throttle body onto the manifold 1 by means of screws. The same solution according to the invention adopted for connecting the proximal end 4b of the tube-like elastic part 4 to the flange 2 can therefore be used also for connection between the distal part 4a of the tube-like elastic part 4 and the possible further flange used for fixing the carburettor or throttle body. In the solution according to the invention, the connection between the proximal end 4b of the tube-like elastic part 4 and the flange 2 (and possibly the connection between the distal end 4a of the tube-like elastic part 4 and the second flange used for fixing the carburettor, the latter flange not being indicated in the drawings) is made exclusively by means of a connection of a mechanical type, thus avoiding the need for the adhesive connection which so far has been considered practically imperative for ensuring the necessary characteristics of a gas and liquid tightness and mechanical resistance to the applied loads. As regards the meaning to be attributed to the fact that, in the solution according to the invention, the connection between the parts 2 and 4 is made in the absence of adhesive connection, the reader is referred to the terminological clarification made previously. In the example of embodiment of the invention illustrated in the next drawings, the aforesaid mechanical connection between the flange 2 and the tube-like elastic part 4 is obtained by providing along the rim of the orifice of the flange 2 a formation 5 having a roughly beak-like profile (with the characteristics better illustrated in what follows) and being designed to co-operate in a relationship of shape fitting with a corresponding groove-like formation 6 provided along the rim of the proximal end 4b of the tube-like elastic part 4. The exemplary embodiment illustrated (which corresponds to a currently preferred embodiment of the invention) envisages that the beak-like formation 5 projects towards the inside of the orifice of the flange 2 starting from the rim of the orifice itself so as to engage the corresponding cavity or groove 6 provided along the rim of the proximal end 4b of the tube-like elastic part 4 in a position corresponding to the outer surface of said elastic part. The possibility of a mechanical fit between the flange 2 and the tube-like elastic part 4 is ensured by the elasticity of the tube-like elastic part 4. Persons skilled in the sector will appreciate the fact that, without prejudice to the modalities of interaction of the complementary formations 5 and 6, the respective locations thereof could be modified without altering the final result achieved. In particular (and without this example necessarily being considered in any way exhaustive of the possible variants of embodiment), it is possible to provide the beak-like formation 5 on the tube-like elastic part 4 and the groove 6 on the flange 2, or else, instead of projecting from the flange 2 towards the inside of the orifice of the said flange 2, the beak-like formation 5 can be provided on a collar-like appendage which surrounds the edge of the aforesaid orifice, with the beak-like formation protruding towards the outside of the said collar, so as to be able to receive, bearing upon it, the proximal end 4b of the tube-like elastic part 4 provided with the groove-like formation 6 on its inner surface. In any case, it is the flange 2 that presses with an appropriate value of preloading (the surface of the tube-like elastic part 4 is slightly projecting with respect to the homologous surface of the flange 2) the surface 7b of the tube-like elastic part 4 against the surface for fixing the manifold on the engine, thus ensuring stable clamping of the manifold. With particular reference to Figure 4, it will be noted that the beak-like formation 5 and the groove-like formation 6 jointly define - with a surface 7a - provided on the formation 5 and a surface 7b provided in the formation 6 - a first connecting region having a general hook-like conformation. In other words, the beak-like formation part 5, which extends from the surface 7a and is distal with respect thereto, forms a sort of hook that is inserted into the groove-like formation 6 so as to embrace, by hooking it, the surface 7b. In a symmetrical way, the apical portion of the proximal end 4b of the tube-like elastic part 4 starting from the surface 7b may be viewed as a sort of hook that embraces, by hooking it, the surface 7a. The overall arrangement is therefore such that any load exerted on the manifold 1 in the direction such as to bring about a possible relative recession (hence a separation) between the flange 2 and the tube-like elastic part 4 results - precisely on account of the hooking action described - in a re-tightening and re-consolidation of the connection between the formation 5 and the formation 6. It will be appreciated that the surfaces 7a and 7b can be brought easily into a position of mutual engagement (hence into a condition of mutual hooking), exploiting the characteristics of elastic compliance of the tube-like elastic part 4, which is made of elastomeric material. The above applies in particular when, according to a first possible embodiment of the manifold 1 according to the invention, the flange 2 and the tube-like elastic part 4 are made as distinct components obtained with two distinct manufacturing processes. The same considerations regarding the hooking-engagement condition between the complementary formations 5 and 6 apply, however, in an identical way also when, according to other possible embodiments of the invention, the manifold is obtained by overmoulding the tube-like elastic part 4 on the flange 2, or else when the manifold 1 is made by co-moulding the tube-like elastic part 4 together with a flange 2 made of a thermoplastic material (for example PA66 containing 30% glass-fibre filler). The first step-like element defined jointly with the surfaces 7a and 7b thus has the function of forming a stable mechanical connection between the flange 2 and the tube-like elastic part 4 primarily as regards the applied loads. This applies also to the vibrational loads and/or loads linked to phenomena of thermal dissipation. In addition to the surfaces 7a and 7b (preferably located in the distal part of the beak-like formation 5), the beak-like formation 5 and the groove-like formation 6 then have two further surfaces which face one another and co-operate together so as to define a second connection region, which also presents a general step-like conformation. The above second connection region is made up of the surfaces 8a and 8b, which are located in the vicinity of the proximal portion (hence the root region) of the beak-like formation 5. This means, in a complementary way, that the surface 8b is located in the apical portion of the proximal end of the tube-like elastic part 4. The said apical portion simply consists of a sort of lip 10 that projects radially from the proximal end 4b of the tube-like elastic part 4. When the manifold 1 is installed on the engine body (designated as a whole by M in Figure 4, where the manifold 1 is represented for reasons of clarity as being set at a slight distance away from the body of the engine M) and the flange 2 is gripped against said body by means of the screws that pass through the openings 3, the lip part 10 is compressed (in effect squeezed) between the outer surface of the body of the engine M and the surface 8a (which in effect constitutes an annular shoulder) of the beak-like formation 5. In the above conditions, the lip 10 ensures the necessary gas and liquid tightness of the connection of the manifold 1 to the body of the engine M without the use of any adhesive. In the solution according to the invention, this result is therefore achieved in a way altogether independent of the mechanical connection established between the flange 2 and the tube-like elastic part 4; the aforesaid mechanical connection is in fact obtained, mainly, at the step defined by the surfaces 7a and 7b. The fluid-tight connection (with respect to the intake opening with which the manifold is associated) is instead achieved precisely by the lip portion of the tube-like elastic part 4 of the manifold 1. The foregoing is obtained without the flange 2 performing a direct function in this direction, except, of course, the function of squeezing (by means of the shoulder surface 8a) the lip part 10 against the surface of the body of the engine M. In Figure 4, the reference number 10a indicates a surface sculpture (usually defined by one or more grooves and/or projections) made on the face of the lip part 10 that is to face towards the body of the engine M, in order to improve further the action of gas and liquid tightness. Once again for the same reason, in the currently preferred embodiment of the invention, the lip part 10 and the proximal end portion 4b of the tube-like elastic part 4 adjacent thereto are sized in such a way that, with the manifold 1 assembled, the surface at which the sculptures 10a are preferably provided is slightly protruding with respect to the homologous surface of the flange 2. In this way, it is possible to confer on the lip 10 a sort of elastic preloading, so improving the characteristics of fluid tightness when the manifold is fixed on the body of the engine M by compressing the aforesaid protruding part. Finally, the reference number 11 designates an annular projection provided along the rim of the tube-like elastic part 4 in a position corresponding to the side of the groove-like formation 6 opposite to the surface 7b that defines the first hooking step between the flange 2 and the tube-like elastic part 4. The annular projection 11, which protrudes from the outer surface of the tube-like elastic part 4, is designed to co-operate with the outer part of the beak-like formation 5 in order to prevent disengagement of the said beak-like formation 5 from the groove-like formation 6. The annular projection 11 can thus be viewed as a sort of third step that is provided to reinforce even further the connection of the flange 2 to the tube-like elastic part 4, so preventing any undesired separation during the storage or handling of the assembled manifold 1 prior to its installation on the engine M. Of course, without prejudice to the principle of the invention, the details of construction and the embodiments may vary widely with respect to what is described and illustrated herein, without thereby departing from the scope of the present invention.

Claims: A manifold comprising a tube-like elastic part (4) made of elastomeric material carrying, associated to at least one end (4b), a flange (2) made of rigid material, said tube-like elastic part (4) and said flange (2) being connected together in conditions of gas tightness and resistance to the applied loads in the absence of adhesive connection, characterized in that said flange (2) and said tube-like elastic part (4) have complementary formations (5, 6) connected together in a relationship of shape fitting, said complementary formations (5, 6) having at least one first (7a, 7b) coupling region, designed to make a mechanical connection between said flange (2) and said tube-like elastic part (4), said first coupling region (7a, 7b) being defined by respective surfaces of said complementary formations (5, 6) fitted together according to a general hook formation, said flange (2) and said tube-like elastic part (4) having at least one second (8a, 8b) coupling region, designed to provide the gas tightness and liquid tightness of the manifold. The manifold according to Claim 1, characterized in that said tube-like elastic part (4) and said flange (2) are distinct components, connected together exploiting the elastic characteristics of said elastomeric material. The manifold according to Claim 1, characterized in that said tube-like elastic part (4) is made of elastomeric material overmoulded on said flange (2). The manifold according to Claim 1, characterized in that said tube-like elastic part (4) is co-moulded with said flange (2). The manifold according to Claim 4, characterized in that said flange (2) is made of plastic material. The manifold according to Claim 5, characterized in that said plastic part is a thermoplastic material, such as a polyamide, preferably PA66. The manifold according to Claim 5, characterized in that said plastic material is a thermosetting material, such as a phenolic resin. The manifold according to Claim 5 or Claim 6, characterized in that said plastic material contains reinforcing material. The manifold according to Claim 8, characterized in that said reinforcing material is in the form of fibres, such as glass fibre. The manifold according to Claim 1, characterized in that said flange (2) is made of a metal material. The manifold according to Claim 10, characterized in that said metal material is chosen from the group comprising: steel, aluminium alloy, Zn+Al+Mg alloy and brass alloy. The manifold according to Claim 10 or Claim 11, characterized in that said flange (2) is made of blanked and/or drawn metal material. The manifold according to Claim 1, characterized in that said first coupling region (7a, 7b) is able, after assembly on the engine, to exert on said tube-like elastic part (4) an action of squeezing to improve further the mechanical stiffness of the coupling. The manifold according to Claim 1, characterized in that said second coupling region (8a, 8b) comprises a surface (8a) which is able to exert on said tube-like elastic part (4) an action of squeezing in conditions of tightness. The manifold according to Claim 14, characterized in that said tube-like elastic part (4) has an apical portion basically shaped like a lip (10) projecting from the tube-like elastic part (4) itself, said lip-like portion (10) being subject to being forced in a relationship of squeezing by at least one surface (7a) of said second coupling region. The manifold according to Claim 15, characterized in that said lip-like portion (10) is provided, on its outer surface with respect to the tube-like elastic part (4), with a sealing surface sculpture. The manifold according to Claim 15 or Claim 16, characterized in that said lip-like portion (10) and/or the region of said tube-like elastic part (4) adjacent to it are at least marginally projecting with respect to said flange part (2). The manifold according to claim 1, characterized in that both the one (5) and the other (6) of said complementary formations consist basically of a projecting beak-like formation (5) and a groove-like formation (6) which receives, at least in part, said beak-like formation (5). The manifold according to Claim 18, characterized in that said first coupling region (7a, 7b) and said second coupling region (8a, 8b) are provided, respectively in the distal part and in the proximal part, with said beak-like formation (5). The manifold according to Claim 18 or Claim 19, characterized in that said beak-like formation (5) and said groove-like formation (6) are provided, respectively, on said flange (2) and on said tube-like elastic part (4). The manifold according to Claim 20, characterized in that said flange (2) has an annular conformation with an orifice, and in that said beak-like formation (5) projects towards the inside of the orifice of said flange part (2). The manifold according to Claim 20 or Claim 21, characterized in that said groove-like formation (6) is provided on its outer surface with said tube-like elastic part (4) at least marginally projecting with respect to said flange part (2). The manifold according to any one of Claims 1 to Claim 22, characterized in that said tube-like elastic part (4) has an annular projection (11) having a function of countering the movement of separation of said flange part (2) with respect to said tube-like elastic part (4).

Inventors: MORONE ALFIO ERSILIO, MORONE, ALFIO ERSILIO
Applicants: ADLER SPA
Application year: 2001
Main classification: F02M35
IPC codes: F02B61, F02M35, F02B75