Electromagnetic valve for controlling fuel vapour flow in a fuel supply device

Abstract: A valve substantially comprising a body (1) having a first cylindrical lateral wall (7) housing an electromagnet and in turn presenting an annular projection (8) extending radially from its outer surface, and a second cylindrical wall (10) smaller in diameter than the first wall (7) and housing a plunger (5) for controlling vapour passage through an orifice (6) formed in a bottom wall (11) of the body (1); the cylindrical walls (7, 10) of the body (1) being inserted inside respective seats (13, 14) formed in a member (15) of the supply device; and the annular projection (8) being designed to rest on a surface (19) of the member (15), for securing the valve to the same.

Description: The present invention relates to a supply device containing an electromagnetic valve for controlling gas, vapour, or gas-vapour mixture flow, in particular, for controlling fuel vapour flow in a fuel supply device. The valve contained in the supply device according to the present invention is particularly suitable for use on the circuit connecting the fuel tank to the intake manifold, and which features an additional tank filled with porous material for retaining the fuel vapours from the fuel tank. The valve, operated electromagnetically, is installed between the additional tank and the manifold, and is controlled by the central control system of the supply device so as to open when the engine is started up and so transfer to the supply manifold a controlled quantity of the fuel vapours accumulated in the porous material in the additional tank. The state of the art in this field is well defined in US-A-3548797 which describes a fuel evaporating preventing device including a fuel absorbtion tank in communication with a fuel bowl of a carburator through a pressure regulating valve incorporated in the carburator. It is also comprised in the state of the art, pursuant Article 54(3) and (4) EPC, EP-A-0534464 which refers to a valve apt to be fitted between a fuel vapour container connected to a fuel tank and a device for controlling the flow of air supplied to an engine of a autovehicle. Known valves of the aforementioned type substantially comprise a body, normally made of plastic material, housing an electromagnet, a core, and a movable anchor which is attracted by the core when the electromagnet is energized, and to which is connected a plunger for controlling passage of the vapours through an orifice connecting the inlet and outlet conduits on the valve. The valve is normally fitted by means of brackets and appropriate fasteners to the vehicle body, and is connected to the intake manifold and the additional tank by means of conduits made of deformable material and the ends of which are connected to respective fittings on the valve, manifold and additional tank. Valves of the aforementioned type present several drawbacks. Firstly, installation of the valve requires additional components, such as the connecting conduits, brackets and various types of fasteners. Secondly, reliability of the circuit portion to which the valve is fitted is impaired both by possible leakage, due to the numerous connections involved, and by the hydraulic resistance of the circuit portion. Thirdly, installation of the valve involves numerous operations, and requires adequate space and access to certain parts of the supply device. Fourthly, by virtue of their design, known valves are invariably noisy and heavy. And lastly, additional work is required at times on the circuit portion to which the valve is fitted, for eliminating defects which can only be detected when the overall supply device of which the valve forms part is actually tested. It is an object of the present invention to provide a supply device containing a valve of the above type designed to overcome the aforementioned drawbacks. According to the present invention, there is provided a supply device containing an electromagnetic valve for controlling gas, vapour, or gas-vapour mixture flow, in particular, fuel vapour flow; the valve substantially comprising a vapour inlet orifice and a vapour outlet orifice communicating with a member of said device, a body housing an annular electromagnet, the inner hole of which houses a core, and a plunger movable between a closed position wherein it closes said outlet orifice, and an open position wherein said orifice is opened; said body comprises a first cylindrical lateral wall housing said electromagnet; characterized by the fact that: said lateral wall has an annular projection projecting from its outer surface; and a second cylindrical lateral wall smaller in diameter than said first wall and housing part of said plunger; said second wall being closed at the bottom by a wall in which said orifice is formed, and being connected to said first wall by an annular wall; said first and second cylindrical lateral walls being inserted inside respective seats formed in said member of said supply device; and said annular projection resting on a surface of said member, for securing the valve to said member. The valve contained in the present invention will be described by way of example with reference to the accompanying drawings, in which: Fig.1 shows a vertical section of the valve according to the present invention; Fig.2 shows an exploded view in perspective of the main components of the valve; Fig.3 shows a view in perspective of the body of a fuel supply device fitted with the valve according to the present invention; Fig.4 shows a section of part of the Fig.3 body. With reference to Fig.1, the valve contained in the present invention substantially comprises a body 1 housing an annular electromagnet 2, the inner hole 3 of which houses a substantially cylindrical core 4, and a plunger 5 movable between a closed position (Fig.1) wherein it closes a vapour outlet orifice 6, and an open position wherein orifice 6 is opened. According to the present invention, body 1 substantially comprises a first substantially cylindrical lateral wall 7 housing electromagnet 2 and having an annular projection 8 projecting from its outer surface 9; and a second cylindrical lateral wall 10 housing the bottom end of plunger 5. Wall 10 is closed at the bottom by a substantially flat wall 11 in which orifice 6 is formed, and is connected to wall 7 by a substantially flat, annular wall 12. Body 1 is conveniently made of suitably thick sheet metal, and is formed, as shown in Fig.1, by means of a series of permanent deformation, in particular drawing, operations. Cylindrical lateral walls 10 and 7 are inserted inside respective cylindrical seats 13 and 14 (Fig.4) formed in a body 15 forming part of the supply device to which the valve is fitted. Body 15 conveniently forms part of a known type of fuel metering and atomizing device, and, in particular, presents a conduit 16 for the air and atomized fuel supplied to the intake manifold on the engine. Seats 13 and 14 communicate with conduit 16 via hole 17. A sealing ring 18 is conveniently provided between seat 13 and the outer surface of lateral wall 10 of valve body 1. Annular projection 8 of valve body 1 rests on surface 19 of body 15, to which it is secured by means of an annular plate 20. The valve contained in the present invention also comprises a disk 24 to which core 4 is fitted (e.g. by means of a rivet) and which rests on electromagnet 2; and a cover 25 resting on disk 24 via the interposition of a sealing ring 26. The top edge 27 of wall 7 of body 1 is permanently deformed on to cover 25 (Fig.1) so as to secure cover 25, ring 26, disk 24 and electromagnet 2 inside body 1. A sleeve 28 projects from cover 25, and presents a vapour inlet hole 29 coaxial with the valve. Cover 25 also comprises a block 30 in which is formed a seat 31 for rheophores 32 connected to electromagnet 2. Sleeve 28 and block 30 are formed in one piece with cover 25 from suitable thermoplastic material. The outer surface 33 of core 4 contacts the inner surface of hole 3 of electromagnet 2, while the outer surface 34 of plunger 5 mates in sliding manner with the inner surface of hole 3, so that plunger 5 is guided by hole 3 of electromagnet 2. The surface of hole 3 presents a number of axial grooves 35 enabling passage of the vapour and communicating with inlet hole 29 in sleeve 28, for which purpose disk 24 presents holes 36, electromagnet 2 presents an annular cavity 37 communicating with grooves 35, and hole 29 presents a flared portion 38 by which it communicates with holes 36. The diameter of inner surface 42 of wall 10 is larger than the diameter of outer surface 34 of plunger 5, so as to form an annular vapour passage 43 between surfaces 42 and 34; and the axis of each groove 35 formed in electromagnet 2 falls within annular passage 43, as shown clearly in Fig.1. For the reasons explained later on, the ratio between the axial length L (Fig.1) and the section of passage 43 ranges between 0.10 and 0.17. Plunger 5 comprises a tubular metal element 44, the inner hole of which houses a core 45 of deformable elastomeric material. Core 45 presents a first head 46 projecting from the bottom surface of element 44 and designed to close vapour orifice 6; and a second head 47 projecting from the top surface of element 44 and designed to contact core 4. The height of head 47 is substantially equal to the size of the gap required between plunger 5 and core 4 when plunger 5 is in the top limit position. Electromagnet 2 conveniently comprises a spool 48 on which is formed a winding 49; and a covering 50 defining a cylindrical lateral surface 51, and a flat top surface 52. From surface 52, there extends a projection 53 to which rheophores 32 are fitted, and which is housed inside an opening 54 in disk 24. Plunger 5 is maintained in the closed position by a coil spring 55. The valve described operates as follows. The valve is fitted to the fuel metering and atomizing device by inserting wall 10 and a portion of wall 7 inside respective seats 13 and 14 in body 15 of the device, as shown in Fig.4; and the valve is locked in the above position by fitting annular plate 20 against annular projection 8 and locking the plate by means of any type of connecting member. Vapour outlet orifice 6 of the valve thus communicates with hole 17 in body 15, and sealing between orifice 6 and hole 17 is assured by sealing ring 18. Sleeve 28 is connected by a hose to the additional tank containing porous material for retaining the fuel vapours from the fuel tank. When electromagnet 2 is activated, plunger 5 is attracted by core 4, in opposition to the pressure exerted by spring 55, so that head 46 is detached from bottom wall 11 of body 1, and vapour inlet hole 29 communicates with hole 17 (Fig.4) in body 15 via flared portion 38, holes 36 in disk 24, annular cavity 37 and axial grooves 35 in electromagnet 2, and annular passage 43 between plunger 5 and wall 10. The conduit so formed inside the valve presents a large section and very little resistance to fuel vapour flow, by virtue of being substantially axial with no sharp changes in direction. When the ratio between length L and the section of annular passage 43 falls within the aforementioned range of values, this has been found to provide simultaneously for two advantages: very low resistance to the magnetic flux through the magnetic circuit portion formed in the bottom of body 1 and in plunger 5; and very little resistance to fuel vapour flow through annular passage 43. Head 47 of soft material provides for silent operation of the valve by cushioning impact between plunger 5 and core 4, as well as for achieving an air gap of the right size by preventing direct contact between the plunger and core. The valve contained in the present invention provides for several major advantages. By virtue of the valve being incorporated in body 15 of the supply device, the circuit to which the valve is fitted is greatly simplified as compared with that of known valves; the reliability of the circuit is enhanced by virtue of direct connection of the valve and body 15, and the high degree of reliability of the valve itself; the space requirement for the valve and the circuit portion to which it is fitted is considerably reduced, by virtue of the valve being fittable directly to body 15; assembly of the valve to the circuit is fast and straightforward; and operating tests may be conducted on the assembly comprising the supply device and valve. Finally, the valve is extremely straightforward in design and therefore highly reliable and cheap to produce.

Claims: A supply device containing an electromagnetic valve for controlling gas, vapour, or gas-vapour mixture flow, in particular, fuel vapour flow; the valve substantially comprising a vapour inlet orifice and a vapour outlet orifice communicating with a member (15) of said device, a body (1) housing an annular electromagnet (2), the inner hole (3) of which houses a core (4), and a plunger (5) movable between a closed position wherein it closes said outlet orifice (6), and an open position wherein said orifice (6) is opened; said body (1) comprises a first cylindrical lateral wall (7) housing said electromagnet (2); characterized by the fact that: said lateral wall (7) has an annular projection (8) projecting from its outer surface (9); and a second cylindrical lateral wall (10) smaller in diameter than said first wall (7) and housing part of said plunger (5); said second wall (10) being closed at the bottom by a wall (11) in which said outlet orifice (6) is formed, and being connected to said first wall (7) by an annular wall (12); said first and second cylindrical lateral walls (7, 10) being inserted inside respective seats (13, 14) formed in said member (15) of said supply device; and said annular projection (8) resting on a surface (19) of said member (15), for securing the valve to said member (15). A supply device as claimed in Claim 1, characterized by the fact that it comprises a disk (24) to which said core (4) is fitted, and which rests on said electromagnet (2); and a cover (25) resting on said disk (24) via the interposition of a sealing ring (26); the top edge (27) of said first cylindrical lateral wall (7) being bent on to said cover (25), for securing said cover (25), said sealing ring (26), said disk (24) and said electromagnet (2) to said body (1). A supply device as claimed in Claim 2, characterized by the fact that said cover (25) comprises a sleeve (28) in which is formed a vapour inlet hole (29) coaxial with the valve axis; and a block (30) in which is formed a seat (31) for the rheophores (32) connected to said electromagnet (2); said sleeve (28) and said block (30) being formed in one piece with said cover (25). A supply device as claimed in one of the foregoing Claims, characterized by the fact that the outer surface (33) of said core (4) contacts the inner surface of said hole (3) of said electromagnet (2), and the outer surface (34) of said plunger (5) mates in sliding manner with the inner surface of said hole (3) of said electromagnet (2), so that said plunger (5) is guided by said electromagnet (2); the inner surface of said hole (3) presenting axial grooves (35) enabling passage of the vapour and communicating with said vapour inlet hole (29) in said sleeve (28). A supply device as claimed in Claim 4, characterized by the fact that the diameter of the inner surface (42) of said second wall (10) of said body (1) is greater than that of the outer surface (34) of said plunger (5), so as to form an annular vapour passage (43) between said two surfaces. A supply device as claimed in Claim 5, characterized by the fact that the axis of each said axial groove (35) of said electromagnet (2) falls within said annular passage (43). A supply device as claimed in Claim 5 or 6, characterized by the fact that the ratio between the axial length (L) and the section of said annular passage (43) ranges between 0.10 and 0.17. A supply device as claimed in any one of the Claims 4 to 7, characterized by the fact that said disk (24) presents holes (36), and said electromagnet (2) presents an annular cavity (37) communicating with said axial grooves (35), so that said axial grooves (35) communicate with said hole (29) of said sleeve (28) via said annular cavity (37) and said holes (36) in said disk (24). A supply device as claimed in one of the foregoing Claims, characterized by the fact that said plunger (5) comprises a tubular metal element (44) the inner hole of which houses a core (45) of deformable elastomeric material; said core (45) presenting a first head (46) projecting from the bottom surface of said tubular element (44) and designed to close said vapour orifice (6), and a second head (47) projecting from the top surface of said tubular element (44) and designed to contact said core (4). A supply device as claimed in Claim 9, characterized by the fact that the height of said second head (47) is substantially equal to the size of the gap required between the plunger (5) and core (4). A supply device as claimed in any one of the Claims 2 to 10, characterized by the fact that said electromagnet (2) comprises a spool (48) on which is formed a winding (49); and a covering (50) defining a cylindrical lateral surface (51) and a flat top surface (52); a projection (53) extending from said top surface (52) and being fitted with said rheophores (32); and said disk (24) presenting an opening (54) for housing said projection (53).

Inventors: FARGNOLI GIANNI, PASQUALI PAOLO, RISI GIUSEPPE, FARGNOLI, GIANNI, PASQUALI, PAOLO, RISI, GIUSEPPE
Applicants: MAGNETI MARELLI SPA, MAGNETI MARELLI S.p.A.
Application year: 1993
Main classification: F02M25
IPC codes: F02M25, F16K31