DRAIN VALVE

Abstract

A drain valve for a compressed air brake system of a vehicle comprises a valve housing defining a valve chamber open at one end and a drain aperture at the opposite end. A poppet has a poppet body at least partially received in the valve chamber and provided with a seal. The poppet is slidable between a closed position in which the poppet and the seal contact the inner wall of the valve housing around the drain aperture thereby closing the drain aperture, and an open position moved away from the drain aperture. A spring urges the poppet to the closed position. The poppet and the seal are incorporated in a single multi-component injection molded plastic part comprising at least two components. The poppet body is formed of a first plastic component and the seal is formed of a second plastic component partially embedded in the first plastic component.

Claims

1. A drain valve for a compressed air brake system of a vehicle, the drain valve comprising: a valve housing (2) defining a valve chamber open at one end and having a drain aperture (6) at the opposite end of the valve housing, a poppet (12) having a poppet body at least partially received in the valve chamber and being provided with a seal (20), the poppet being slidable between a closed position in which the seal contacts the inner wall of the valve housing around the drain aperture (6) thereby closing the drain aperture, and an open position moved away from the drain aperture, and a spring (28) acting between the valve housing and the poppet urging the poppet to the closed position, the poppet (12) and the seal (20) being incorporated in a single multi-component injection molded plastic part comprising at least two components, the poppet body being formed of a first plastic component and the seal formed of a second plastic component partially embedded in the first plastic component, in that the poppet (12) comprises a disc (18) disposed in the valve chamber and a stem (16) extending from the disc and through the drain aperture (6), the first plastic component of the single multi-component injection molded plastic part forming the disc (18) and the stem (16), the disc comprising an annular groove coaxial with the stem and extending partly through the disc, the second plastic component filling the annular groove and projects beyond the disc surface to form an annular sealing ring embedded in the first plastic component of the disc of the poppet body, and in that the stem comprises an end region remote from the disc with the end region defining a through hole (14) for receiving a ring, wherein a slot (15) of smaller width than the diameter of the through hole connects the hole to the exterior surface of the stem such that a ring can be pressed into the slot and can, under elastic deformation of the stem around the slot, be pushed through the slot and into the hole such that the stem snaps into place once the ring reached the hole.

2. The drain valve according to claim 1, wherein the first and second plastic components of the single multi-component injection molded plastic part include interlaced structures (19) of the first and second components to provide for a secure interconnection and a high stability of the composite multi-component injection molded plastic part.

3. The drain valve according to claim 1, wherein channels extend through the disc of the poppet body which connect the annular groove to the opposite surface of the disc and the channels being filled with the second plastic component.

4. The drain valve according to claim 1, wherein the first plastic component has a Shore hardness D in the range between 65 and 85.

5. The drain valve according to claim 1, wherein the second plastic component has a Shore hardness A in the range between 50 and 70.

6. The drain valve according to claim 1, wherein the second plastic component comprises a thermoplastic elastomer.

7. The drain valve according to claim 1, wherein the first plastic component comprises a polyamide.

8. The drain valve according to claim 1, wherein the first plastic component comprises a fibre reinforced polyamide.

9. The drain valve according to claim 7, wherein the polyamide is a polyamide 12.

10. The drain valve according to claim 7, wherein the second plastic component consists of a fibre reinforced polyamide including 30-50 vol. % fibres.

11. The drain valve according to claim 2, wherein the first plastic component has a Shore hardness D in the range between 65 and 85.

12. The drain valve according to claim 2, wherein the second plastic component has a Shore hardness A in the range between 50 and 70.

13. The drain valve according to claim 2, wherein the second plastic component comprises a thermoplastic elastomer.

14. The drain valve according to claim 2, wherein the first plastic component comprises a polyamide.

15. The drain valve according to claim 2, wherein the first plastic component comprises a fibre reinforced polyamide.

16. The drain valve according to claim 8 wherein the polyamide is a polyamide 12.

17. The drain valve according to claim 8, wherein the second plastic component consists of a fibre reinforced polyamide including 30-50 vol. % fibres.

18. The drain valve according to claim 3, wherein the first plastic component has a Shore hardness D in the range between 65 and 85.

19. The drain valve according to claim 3, wherein the second plastic component has a Shore hardness A in the range between 50 and 70.

20. The drain valve according to claim 3, wherein the second plastic component comprises a thermoplastic elastomer.

21. The drain valve according to claim 3, wherein the first plastic component comprises a polyamide.

22. The drain valve according to claim 3, wherein the first plastic component comprises a fibre reinforced polyamide.

23. The drain valve according to claim 9, wherein the second plastic component consists of a fibre reinforced polyamide including 30-50 vol. % fibres.

24. The drain valve according to claim 4, wherein the second plastic component has a Shore hardness A in the range between 50 and 70.

25. The drain valve according to claim 4, wherein the second plastic component comprises a thermoplastic elastomer.

Description

[0023] The invention will be described in the following in connection with the preferred embodiment referring to the drawings in which:

[0024] FIG. 1 shows a cross-sectional view of a drain valve according to the present invention;

[0025] FIG. 2 shows a bottom view of a poppet of a drain valve according to the present invention;

[0026] FIG. 3 shows a perspective view of a poppet for a drain valve according to the present invention cut in the middle; and

[0027] FIG. 4 shows a further cut view as in FIG. 3, wherein it is further cut in a plane perpendicular to the longitudinal axis of the poppet stem.

[0028] The drain valve shown in FIG. 1 in cross-sectional view comprises a valve housing 2 having a valve chamber having an open end 4 at one of its ends and a drain aperture 6 at its opposite end. A poppet 12 is partially received in the valve chamber in such a manner that a disc 18 of the poppet is disposed within the valve chamber and that a poppet stem 16 extends therefrom through the drain aperture 6 to the outside. The poppet is further provided with a sealing ring 20.

[0029] A spring 28 is resting on a shoulder near the lower end of the valve chamber and abuts with its opposite end against the disc 18 of the poppet to urge the poppet to the closed position in which the sealing ring 20 is pressed against the inner wall of the valve housing 2 around the drain aperture 6 to close the valve.

[0030] The valve housing 2 is adapted to be mounted in the wall of a compressed air brake system. For this purpose the housing 2 is also provided with a circumferential groove in which a sealing ring 30 is disposed such that the valve housing 2 may be mounted in the wall of the air brake system in a sealed manner.

[0031] As can be seen in FIGS. 2 to 4 the poppet is formed as a two-component injection molded part, wherein the poppet body is formed of a first plastic component which forms the poppet stem 16 at the poppet disc 18. The poppet disc is injection molded with a circumferential groove extending concentrically around the longitudinal axis of the poppet stem. This groove is filled up in a second injection molding step with a second plastic component in such a manner that the second plastic component extends beyond the surface of the groove on the side of the poppet stem 16 to form an annular sealing ring. The groove in the poppet disc 18 is further provided with holes or channels which are going through the disc through which the second plastic component is injected in the second injection step and which are likewise filled with the second plastic component. The lower surface of the second plastic component in the holes is designated by reference numeral 21.

[0032] As can be seen for example in FIG. 3 the groove in the poppet disc is further provided with an undercut or interlocking structure 19 such that the first and second plastic component of the poppet are interlaced or interlocked such that the annular sealing ring 20 is firmly connected to the poppet body.

[0033] As can be seen in FIGS. 1, 3 and 4 the end portion of the stem remote from the disc 18 includes a though hole 14. This through hole 14 is connected by an adjoining slot 15 to the outer surface and to the exterior of the stem 12. The width of this slot 15 is smaller than the diameter of the hole 14. The purpose of this arrangement is to allow a snap-in connection of a ring. The ring is dimensioned such that a portion of the circumference of the ring fits into the through hole 14, wherein the thickness of the ring is larger than the width of the slot, but slightly smaller or equal to the diameter of the trough hole 14. In order to attach the ring to the poppet a portion of the ring is introduced in the widened upper opening of the slot 15 and pushed into the slot 15. The portions of the stem surrounding the slot are elastically deformed when the ring is pushed through the slot 15, whereafter these portions snap back into place once the ring has reached the hole 14. Such a way of attaching a ring to the poppet is much simpler than in conventional drain valves. Conventionally the poppet of such drain valve had a through hole with no connection to the outer surface of the stem. A split ring or key-ring had to be used which was first spread open, whereafter the open ends were introduced into the through hole from its opposite ends. The present invention allows to use a simple continuous ring which can be attached to the poppet by a snap-in action.

[0034] In an alternative embodiment the ring at the end of the poppet remote from the disc may be integrally formed with the stem of the poppet by injection molding. Since the ring is dimensioned such that it allows to insert a finger of the operator, it has a larger outer diameter than the diameter of the drain aperture 6 for typical drain valve dimensions. For this reason it is necessary that the ring can be folded or elastically deformed so that it can pass the drain aperture 6 when the stem 16 of the poppet 12 is advanced through the drain aperture 6 during assembly of the drain valve. This ability to deform the ring during assembly can be achieved for example by forming the ring in the injection molding procedure of a sufficiently elastic plastic component. Alternatively, the ring can be provided with hinge zones in form of solid hinges which allow folding of certain portions of the ring such that it may pass the drain aperture 6 during assembly.

[0035] For the first plastic component preferably a 30 vol. % glass fibre reinforced, heat stabilized polyamide 12 with injection molding grade is used. Such a material has the following mechanical properties:

TABLE-US-00001 Standard Unit State Tensile E- 1 mm/min ISO 527 MPa cond. 6000 Modulus Tensile 5 mm/min ISO 527 MPa cond. 105 strength at break Elongation 5 mm/min ISO 527 % cond. 8 at break Impact Charpy, ISO kJ/m.sup.2 cond. 80 strength 23° C. 179/1eU Impact Charpy, ISO kJ/m.sup.2 cond. 80 strength −30° C. 179/1eU Notched Charpy, ISO kJ/m.sup.2 cond. 20 impact 23° C. 179/1eA strength Notched Charpy, ISO kJ/m.sup.2 cond. 15 impact −30° C. 179/1eA strength Shore ISO 6 8 — cond. 77 hardness D The abbreviation cond. stands for “conditioned”.

[0036] Various modifications of the preferred embodiment shown in the drawings can be made without deviating from the teaching of the present invention as defined in the following claims. For example, the poppet and the valve chamber do not have to be circular but could also have other shapes as long as the end piece of the poppet or disc disposed in the valve chamber fits to the design of the inner walls of the valve chamber such that the poppet can slide within the valve chamber to be lifted off the valve seat to open the drain valve. In addition, the poppet and the seal can be made as a composite plastic component comprising more than two plastic components.