Tank filler neck with a negative and positive pressure relief valve

The invention relates to a tank nozzle which has an outer wall and an inner wall and forms a space in its interior which is closed to the environment during operation and opened for refueling, with a vacuum-overpressure valve being provided for pressure equalization when the space is closed. The filler neck can either be closed by means of a screw cap or a bayonet cap, or it can be of the capless design.

In the first case, it can be designed without any internal flaps because the space is closed by the screw or bayonet cover. In the second case, it is equipped with a flap at its upper end that can be pushed open inwards by the filling pipe of a filling nozzle. Another flap - a so-called lead-free flap - can be arranged further inside. The closed space formed in the tank nozzle merges into the interior of the tank, so there is the same pressure in it as in the tank. This pressure fluctuates. When the tank is heated, an overpressure is created in it and thus in the room. When the tank contents cool down and when fuel is withdrawn, a negative pressure forms in the tank, which is also undesirable.

It is therefore known, in conventional tank systems, to install an underpressure-overpressure valve in the cover (for example screw cover) that closes off the tank neck towards the outside. Such tank caps are described in AT PS 403 144 and DE 102 16 811 A1. They make the fuel cap (which is easily lost) expensive and, moreover, bulky. Such valves cannot be implemented in the case of tank nozzles without a cover, because the filling pipe of a fuel nozzle must be guaranteed to pass through. In the case of tank filler necks without a lid, an inwardly opening flap is provided. However, if there is overpressure in the tank, this is pressed even more tightly to its seat and cannot compensate for a negative pressure in the tank because of the considerable force of its closing spring. Because the flap is pushed open by the filling pipe of the filling nozzle, it is forbidden to install a valve in the flap.

It is therefore the object of the invention to enable pressure equalization in both directions with a solution that is as simple and space-saving as possible. The fuel cap should be as simple and cheap as possible or even superfluous. The pressure equalization should therefore also be guaranteed in the case of tank nozzles without a lid.

According to the invention, the negative pressure - positive pressure valve is arranged in the annular space formed between the outer wall and the inner wall, which valve communicates on the one hand with the space and on the other hand with the atmosphere and to reduce a pressure difference between the space and the atmosphere in one way or the other Direction opens. Regardless of the structural design and the choice of material, there is practically always a free annular space between the inner wall and the outer wall. This space is used to accommodate the vacuum - overpressure valve without the outside diameter of the tank nozzle becoming larger. As a result, either the tank lid can be very simple or, in the case of a design without a lid, the insertion of the filling pipe and the function of a flap are not hindered.

In an advantageous embodiment, the negative-positive pressure valve consists of a dividing wall lying in a plane normal to the axis with axial openings distributed over the circumference, which divide the annular space between the outer wall and inner wall into a first upper annular space in communication with the atmosphere and into a second divides the lower annulus communicating with the interior, furthermore from a first valve ring in the first annulus, which is loaded by a first valve spring against the partition, and still further a second valve ring in the second annular space, which is loaded by a second valve spring against the other side of the partition (claim 2). The axial openings in the partition are distributed over the circumference, preferably circular holes, on each of which a valve ring is arranged. Regardless of their design, the valve rings are simple and structurally identical parts, regardless of their design, and there is also enough space in the two spaces for an all-round spiral spring, or several cylinder springs, disc springs or a wave spring.

AT 009 752 U1

A particularly elegant development is that the two valve rings each have alternating first and second zones in the circumferential direction, with the first zone resting on the partition wall under load from the spring and the second zone being offset in the axial direction so that it does not rest on the partition wall , and that a first zone of the first valve ring on one side of the partition is opposite to a second zone of the second valve ring on the other side of the partition (claim 3). Because an adjacent first zone of the valve ring on one side of the partition wall is always faced with a recessed second zone (which does not close the holes because of the smaller axial height of the valve ring there), adjacent zones are alternately available for one or the other flow direction . In order to ensure this assignment of the zones, it is easiest to guide the valve rings to secure against rotation in the axial direction (claim 4).

The arrangement of the negative-positive pressure valve in the annular space gives the freedom to choose its height, so that no flow channels are required. The first annular space is advantageously connected to the atmosphere via first openings in the outer wall of the tank nozzle and the second annular space to the interior via second openings in the inner wall of the tank nozzle.

If there is a flap inside the filler neck, a preferred embodiment of the invention consists in that the negative pressure-overpressure valve is arranged in the annular space higher than the flap (claim 6). This ensures that no fuel gets to the outside even if you refuel very quickly.

The invention is described and explained below with reference to illustrations of a possible embodiment. They represent:

- Fig. 1: A tank nozzle according to the invention in longitudinal section,

- Fig. 2: Details A (Fig. 2a) and B (Fig. 2b) in Fig. 1, enlarged,

- Fig. 3: Section according to III-III in Fig. 2a,

FIG. 4: a rolled-up section according to IV-IV in FIG. 3.

In Fig. 1, the outer wall of a tank nozzle is denoted by 1, its inner wall by 2 and a pipe part adjoining both of them and leading to a fuel tank (not shown) is denoted by 3. The outer wall 1 is made of sheet metal and ends at the top in an all-round bead 4. The inner wall 2 is an injection-molded plastic part that is sealed against the outer wall 1 by means of O-rings 5, 5 'and forms an inwardly tapering guide wall 7 on one side. In the exemplary embodiment shown, this ends in a passage opening 8 for the filling pipe of a filling nozzle, not shown, which is closed by a flap 10. The flap can be pivoted inwardly about an axis 11 fastened to the inner wall 2 against the force of a leg spring 12. The longitudinal axis of the tank nozzle, which is essentially circular in cross section, is denoted by 9.

The flap 10 separates an antechamber 13 located above it from a space 19 located below it, downstream, which is connected directly to the fuel tank via the pipe part 3. The same pressure prevails in space 19 as in the fuel tank, which is dependent on various influences and is therefore variable. The anteroom 13 above the flap 10 is closed here by a flap 15 loaded by a further pressure spring 16. This further flap 15 is also pushed open by the filling pipe of the fuel nozzle when refueling. The flap has been described for the sake of completeness, but the invention is also suitable for embodiments without a flap.

The annular space 18 between the outer wall 1 and the inner wall 2 is separated by a partition wall 21 into a first annular space 22 and a second, second annular space 23 located below it. Between the two annular spaces 22, 23 there is an underpressure AT 009 752 U1 that is summarized as 20

Overpressure valve is provided, which serves to equalize pressure between the space 19 and the atmosphere outside the outer wall 1. Since the pressure in space 19 can be both greater and less than atmospheric pressure, the vacuum-overpressure valve 20 has to release the flow once in one direction and another time in the other, depending on the sign of the pressure gradient.

The vacuum-overpressure valve 20 will now be described with reference to FIGS. 2a, 3 and 4. The first annular space 22 is connected to the atmosphere via first openings 25 in the outer wall 1, the second annular space 23 via second openings 26 to the space 19. The two annular spaces 22, 23 are separated from one another by the partition 21, which over their circumference has distributed to the longitudinal axis 9 parallel holes evenly distributed over the circumference. A circular valve ring acts on both sides of these holes, namely a first valve ring 31 on the upper side and a second valve ring 32 on the lower side Art) loaded in the closing direction towards the partition wall 21. The valve springs 33, 34 are supported with their ends facing away from the valve rings 31, 32 on corresponding surfaces 35, 36 of the inner wall 2.

When looking at FIGS. 3 and 4, the special shape of the valve rings 31, 32 can be seen. These (circular) rings are flat on their side facing away from the partition 21, but are divided into alternating zones 40, 41, 42, 43 on their side facing the partition 21, the zones 41, 43 forming a setback 44 and thus when adjacent Valve ring 31, 32 do not cover the holes assigned to them, but transverse passages 45, 46 of a certain height (44 in Fig. 4) form. A plurality of holes 30 are preferably assigned to a zone. The setbacks 44 are recesses, in particular millings, over the entire radial width of the valve rings 31, 32, so that they establish the connection between the holes 30 assigned to them and the respective annular space 22 or 23. The first valve ring 31 alternately has the zones 40, 41 (see FIGS. 3 and 4) and the second valve ring 32 alternately has the zones 42, 43. The two valve rings 31, 32 are arranged in relation to one another in such a way that a recessed second zone 43 of the second valve ring 32 is assigned to a first adjacent zone 40 of the first valve ring 31 on the other side of the partition 21. So that the two valve rings 31, 32 retain their assignment, both are secured against rotation. In FIG. 3 this is shown for the first valve ring 31 as a nose 51 which engages in a vertical groove 50 in the inner wall 2.

The section lines aa and bb, to which the enlarged sections of FIGS. 2a and 2b are assigned, are shown in FIG. 4. Correspondingly, the lower transverse passage 45 formed by the offset can be seen in FIG. 2a and the transverse passage 46 formed in the first valve ring 31 in FIG. 2b. The offset 44 is also shown in FIG. 4.

The function of the vacuum-overpressure valve 20 is described with reference to FIG. 1: in the right half of FIG. 1, the valve 20 acts as an overpressure valve. The flow is shown by the line 54. The pressurized air-fuel vapor mixture from the space 19 flows through the opening (s) 26 (see FIG. 2a) into the second annular space 23 laterally past the second valve ring 32 into the transverse passages 45 and further into the holes 30 assigned to them. The pressure in the holes 30 lifts the first valve ring 31 so that it releases the flow into the first annular space 22, from which the outflowing fuel-air mixture passes through the first opening 25 into the open.

In the left half of FIG. 1, there is an underpressure in space 19. Air from the atmosphere flows through the opening 25 into the first annular space 22, through the transverse passages 46 (see FIG. 4) into the associated holes 30. The excess pressure in these presses the second valve ring 32 downwards, so that the associated holes 30 to the second annular space 23 are open. This (23) is connected to the space 19 via the second openings 26. This ensures pressure equalization in both directions.