DOUBLE-ACTING BREATHER VALVE, PARTICULARLY FOR FUEL TANKS OF MOTOR VEHICLES

Abstract: A double-acting breather valve, particularly for fuel tanks of motor vehicles, comprises a valve body (1) having an internal cavity (1a) and provided with two opposite apertures (5, 6) which open into the internal cavity (1a), and valve means (4, 7, 9) for putting the two said opposite apertures (5, 6) into communication with each other when the external ambient pressures which communicate with the said aper­ tures are different. The said valve means comprise a first element (9) mounted slidably with play in the internal cavity (1a) of the valve body (1), having a through passage (12), a first spring (11) which urges the said first element (9) against an annular abutment (4a) of the valve body, a second element (8) mounted slidably with play (13) in the cavity (1a) of the valve body (1), on the side of the first element (9) opposite the said first spring (11), and provided with an obturator (7) for controlling the communication through the said passage (12) between the two zones of the internal cavity (1a) separated by the first element (9), and a second spring (10) which urges the second element (8) towards the first element (9).

Description: Double-acting breather valve, particularly for fuel tanks of motor vehicles The present invention relates to double-acting breather valves, particularly for fuei tanks of motor vehi ci er., of the type comprising: a valve body hang an internal cavity and two opposed apertures which open into the said internal cavity and valve means for putting the two said opposed apertures into communication with each other when different eternal ambient pressures communicate with the said apertures. The object of the present invention is the provisior; of valve of the type specified above made up of a reduced number of parts, of simple construction and low cost With the said object in view the invention provides a breather valve of the type specified, characterised in that the said valve means comprise: a first element mounted slidably with play in the internal cavity of the valve body and having a, through passage, a first spring which urges the said first element against an annular abutment in the valve body; a second element mounted slidably with play in the internal cavity of the valve body, on the side of the first element opposite the said first spring, and provided with an obturator for controlling communication through the said passage between the two zones of the internal cavity separated by the first element, and a second spring which urges tr¯ secona element towards the first element. 5* In a preferred embodiment, the valve body is defined by two cup-shaped pressings withfacing cavities and circumferential flanges welded together; between the said flanges there is fluid-tightly clamps an annular sealing gasket which projects into the internal cavity and defines the said annular abutment According to a further characterist:ic,the said first element and the said second element each have a cylindrical external wall mounted slidably with play in the internal cavity of the valve body. In the said preferred embodiment,the said obturator is separate from the second element and has a spherical shape In this example, moreover, the first element and the second element have two central concave parts facing each other and arranged to cooperate with the said spherical obturator. In another embodiment,the said obturator is constituted by a portion of the second element, cooperating preferably with a seal carried by the said first element. Further characteristics and advantages of the present invention will become apparent from the description which follows with reference to the appended drawings, provided. by way of non-limiting example, in which: Figures 1 to 3 illustrate a preferred embodiment of a breather valve for fuel tanks of motor vehicles according to the present invention, in three different conditions of operation, and Figures 4 and 5 illustrate two further embodimerits. Figure 1 illustrates the breather valve in a rest condition, corresponding to the condition in which the pressure within the fuel tank is equal to atmospheric pressure. Figure 2 illustrates the breather valve in a first operative condition, corresponding to the condition in which the pressure within the fuel tank is greater than atmospheric pressure. Figure 3 illustrates the breather valve in a second operative condition, corresponding to the condition in which the pressure within the fuel tank is lower than atmospheric pressure. With reference to Figure 1, the breather valve comprises a valve body 1 including two cup-shaped pressings 2, 3 having cavities facing each other and having respective circumferential flanges 2a, 3a which are welded together. Between the flanges 2a, 3a there is interposed an annular sealing gasket 4 which defines an annular abutment within the cavity la defined by the two pressings 2, 3. The breather valve is fitted in the upper wall of the fuel tank of a motor vehicle. The cup-shaped pressing 2 has a central aperture 5 through which the internal cavity of the body 1 communicates with the atmosphere. The cup-shaped pressing 3 has a central aperture 6 which puts the internal cavity la into communication with the internal cavity of the fuel tank (the fuel within the tank is always maintained in normal operating conditions - at a level lower than that of the aperture 6). Within the cavity la of the valve body 1 there is disposed first and second elements 9, 8 having respective central concave parts 9a, 8a facing each other between which there is interposed a spherical obturator 7. The first element 9 has a cylindrical external wall 9b which is mounted slidably with play within tne internal cavity Ia of the valve body 1. Between the first element 9 and the bottom of the cup-shaped pressing 3 there is interposed a spring 11 which urges the first element 9 against the annular abutment 4a defined by the annular sealing gasket 4. The second element 8 also has an external cylindrical wall 8b which is mounted slidably within the internal cavity la of the valve body, on the side of the first element 9 opposite the spring 11. A second spring 10 is interposed between the base of the cup-shaped pressing 2 and the second element 8, so as to urge the second element 8 and with it the spherical obturator 7 towards the first element 9. The latter has a central passage 12 which interconnects the two parts of the internal cavity la separated by the first element 9. The reference numerals 13, 14 indicate the respective clearance gaps or play between the cylindrical walls 9b, 8b and the corresponding cylindrical walls of the cup-shaped pressings 3, 2 respectively. With reference to Figure 1, when the pressure within the fuei tank is equal to amospheri pressure, the spring 11 holds the first element G against the annular abutment 4a defined by the annular sealing gasket 4, and the spring 10 urges the second element S, and with it the spherical obturator 7, against the central concave part 9a of the first element 9. Under these conditions the fuel tank is hermetically sealed, since the apertures 5, 6 are not in communication with each other. With reference to Figure 2, if the pressure within the fuel tank becomes greater than atmospheric pressure, the spherical obturator 7 is displaced with the second element 8, causing compression of the spring 10. In consequence, the aperture 6 is put into communication with the aperture 5 through the passage 12. the space between the two elements 8, 9 and the clearance gap 13. When the pressure within the fuel tank returns to atmospheric pressure the second element 8 returns with the spherical obturator 7 to the position illustrated in Figure 1. With reference to Figure 3, if the pressure within the fuel tank becomes lower than atmospheric pressure, the spherical obturator 7 is displaced in the direction of the first element 9, causing compression of the spring 11. In the course of this movement, the second element 8 is maintained in contact with the spherical obturator 7 by the spring 10. The element 9 thus becomes spaced from the annular abutment 4a defined by the annular sealing gasket 4, so that the aperture 6 is put into communication with the aperture 5 through the clearance gap 14, the chamber defined between the two elements 8, 9 and the clearance gap 13. When the pressure within the fuel tank returns to atmospheric pressure the spherical obturator 7 returns to the position illustrated in Figure 1. As will be evident from the preceding description, the double-acting valve illustrated in the drawings has two valve seats: a first valve seat is constituted by the central concave portion 9a of the element 9, cooperating with the spherical obturator 7; z second valve seat is constituted by the annular abutment it defined by the annular sealing gasket 4, cooperating with the element 9. Although in the example described above the obturator 7 is in the form of a spherical ball and is separated from the element 8, it is also possible to provide an obturator of different configuration and/or fabricated in one piece with the element 8. By way of example, Figure 4 illustrates an embodiment in which the obturator 7 is constituted by a spherical appendage projecting from the element 8. In this Figure, the various parts of the valve are indicated by the same reference numerals as in Figure 1. Figure 5 illustrates a further embodiment of the valve according to the invention. In Figure 5, also, those parts in common with Figure 1 are indicated by the same reference numerals. The difference with respect to the valve of Figure 1 lies in the fact that the obturator 7 is constituted by a circumRerentia ] ridge 8b projecting from the base wall 8a of the element 8 and cooperating with an annular sealing washer 16 mounted in a seat 15 of the element 9. Compared with the valve of Figure 1, the valve of Figure 5 has the advantage of having a simpler and less expensive structure The obturator has, moreover, a relatively reduced mass, so that it is not subject to undesirable displacements in response to vibrations during movement of the motor vehicle structure. Naturally, while adhering to the principle of the invention, details of construction and embodiments may be varied widely with respect to what has been described and illustrated purely by way of example, without thereby departing from the scope of the present invention.

Claims: CLAIMS Double-acting breather valve, particularly for fuel tanks of motor vehicles, comprising: - a valve body (1) having an internal cavity (lea) and having two opposite apertures (5, 6) which open -into the internal cavity (la), and - valve means (4, 7, 9) for putting the two said opposite apertures (5##'6#into-communication with each other when these apertures are in communication with different ambient pressures, characterised in that the said valve means comprise: - a first element (9) mounted slidably with play (14) in the internal cavity (lea) of the valve body (1) and having a through passage (12), - a first spring (10) which urges the said first . element (9) against an annular abutment (4a) of the valve body (1), - a second element (8) mounted slidably with play (13) in the internal cavity of the valve body, on the side of the first element (9) opposite the said first spring (11), and provided with an obturator (7) for controlling communication through the said passage (12) between the two zones of the internal cavity (lea) separated by the first element (9), - a second spring (10) which urges the second element (8) towards the first element (9). 2 Valve according to Claim 1, characterised in that the valve body (1) is defined by two cup-shaped pressings (2, 3) having internal cavities facing each other and circumferential flanges (2a, 3a) welded together, and in that between the said flanges there is clamped an annular sealing gasket (4) which defines the said annular abutment (4a). 3. Valve according to Claim 1, characterised in that the said first element: (9)and the said second element (8) each have a cylindrical external wall (9b, 8b) mounted slidably with play (14, 13) in the jnt.rna! cavity(1a) of the valve body (1). 4. Valve according to Claim 1, characterised in that the said obturataoF (7) is separate from the said second element (8). 5. Valve according to Claim 4, characterised in that the said obtruator (7) is of spherical form. 6. Valve according to Claim 5, characterised in that the first element (9) and the second element ce, have two central concave parts (9a, 8a) which face each other and which cooperate with the spherical otlturator (7). 7. Valve according to Claim 1, characterised in that the said obturator (7) comprises a part of the said second element (8). 8. Valve according to Claim 1, characterised in that the said obturator (7) is in one piece with the said second element (8), and in that the said obturator (7) cooperates with a sealing washer (loo) carried by the said first element (9). 9. Valve according to Claim 8, characterised in that the first and the second elements (9, 8) have two central parallel walls (9a, 8a) which face each other and in that the said obturator is constituted by a circumferential ridge (7) projecting from the central wall (8a) of the second element (8), the said sealing washer (16) having an annular body lodged in a correspanding annular seat (15) in the central wall l9a) of¯the said first element (9).

Inventors: LUCCHINI, GIUSEPPE
Applicants: FIAT AUTO S.P.A.
Application year: 1984
Main classification: F16K17
IPC codes: F16K17, B60K15