Abstract:
A poppet valve assembly having a spring for holding the valve in a closed position and permitting opening of the valve in response to air pressure including valve stem alignment provided by a sleeve in engagement with the spring and having a cross pin supporting surface for engagement with the pin in shear to avoid bending.

Description:
This Utility Patent Application claims priority from Provisional Patent Application Serial No. 60/146,868 filed Aug. 3, 1999. 
    
    
     FIELD OF INVENTION 
     This invention relates to poppet valves and more specifically to poppet valves utilized for communicating air pressure into a mold to eject the molded articles after molding. 
     DESCRIPTION OF THE RELATED ART 
     A poppet valve such as that shown in the prior art drawing FIG. 1 has been utilized in the ejecting of molded articles by communicating air pressure to the valve as the mold opens. Difficulties have been encountered, such as axial angular displacement when the valve opens because of the lack of guidance for the poppet valve stem. Also, the cross pin which limits the movement of the poppet valve out of the valve seat is subjected by the spring to a cantilevered load which may bend the pin. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention is directed to a poppet valve construction which prevents axial angular displacement as the valve opens and controls the axial linear displacement. The cross pin is also positioned to eliminate the cantilevered load on the pin by the spring. 
     In accordance with one aspect of the invention there is provided a poppet valve assembly comprising a valve body member having a valve seat, a poppet valve member for seating in the valve seat, orifices in the valve seat in communication with a source of air pressure, the poppet valve member having a valve stem extending through a cylindrical opening in the valve body member characterized by a cylindrical sleeve member having an outer diameter substantially the same as the diameter of the cylindrical opening in the valve body member with a length of reduced diameter providing a shoulder for engaging a spring and an inner diameter substantially the same as the diameter of the valve stem, the valve body having slots for receiving a cross pin extending through the valve stem and the sleeve member, and a coil spring interposed between the sleeve and the body member with the spring engageable with the shoulder for closing the poppet valve whereby the sleeve guides the valve stem and prevents axial angular displacement of the valve stem and the sleeve through its sliding fit over the valve stem provides a shear plane for forces applied to the cross pin. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     FIG. 1 is a fragmentary sectional view of a mold illustrating the prior art and showing poppet valve of a type used heretofore. 
     FIG. 2 is a sectional view like FIG. 1 showing a poppet valve embodying the present invention. 
     FIG. 3 is an end view of the poppet valve body with the poppet valve removed taken along the plane of line  3 — 3  in FIG.  2 . 
     FIG. 4 is a sectional view of the valve body shown in FIG. 3 taken along the plane of line  4 — 4  in FIG.  3 . 
     FIG. 5 is a plan view of the poppet valve member with the valve stem as shown in FIG.  2 . 
     FIG. 6 is a plan view of the sleeve as shown in FIG.  2 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIG. 1, a fragmentary sectional view of a poppet valve assembly  10  of the type used in the prior art is shown mounted in a mold face  12  of a first mold half  14  spaced from a second mold half  16  between which a molded object  18  is contained upon injection from a suitable source (not shown). After injection of the mold material forming the molded object  18 , the second mold half  16  is moved away from the first mold half  14 . At this time compressed air is supplied to the poppet valve assembly  10  opening the valve and communicating compressed air to the molded object  18  which separates it from the first mold  14 . The molded object  18  is carried away from the first mold half  14  to a position where it can be removed from the second mold half  16 . In accordance with the prior art poppet valve assembly  10  has poppet valve member  20  which is moved away from a valve seat  22  by compressed air communicated to the valve seat  22  through a passage  24  in the first mold half  14  and air vents  26  in the valve seat. The compressed air moves the poppet valve member  20  away from the valve seat  22  and compresses a coiled spring  28  which is disposed between a flange on the valve body member  22  and a cross pin  30  extending through a valve stem  32  of the poppet valve member  20 . After the flow of compressed air between the poppet valve member  20  and a valve seat  34 , has been discontinued the spring  28  will return the poppet valve member  20  to the seated position. Although this prior art poppet valve assembly  10  has operated satisfactorily in many applications, it has been found that in some cases the bottom of the valve stem  32  is not guided which causes wear on the sealing surface of the poppet valve member  20 . This has caused the poppet valve assembly  10  to fail. Also the poppet valve member  20  may not seat in the valve seat  34  after being used because the valve stem  32  is not guided for a concentric return by the spring  28 . This is not desirable because the poppet valve member  20  needs to be flush with the mold surface  12  so as not to cause irregularities or flaws in the molded object  18 . 
     Problems have also been had with the cross pin  30  in that the spring  28  bears directly on the pin and exerts a cantilevered force which has caused the pin and spring to wear resulting in a malfunction of the poppet valve assembly  10  of the prior art. 
     With reference to FIG. 2, a poppet valve assembly  40  embodying the invention is shown mounted in the same position as the prior art poppet valve assembly  10  in FIG.  1 . Where the parts shown in FIG. 2, are the same as the parts shown in FIG. 1 they are designated by the same numerals as in FIG. 1, but with an prime symbol. The poppet valve assembly  40  is mounted in the mold face  12 ′ of a first mold half  14 ′ spaced from a second mold half  16 ′ providing a space for a molded object  18 ′. The poppet valve assembly  40  is mounted in a cylindrical recess  42  in the mold face  12 ′ and includes a valve body member  22 ′ as shown in FIGS. 2 and 4. The valve body member  22 ′ has a valve seat  34 ′ for receiving a poppet valve member  20 ′ having a valve stem  32 ′ extending through a sleeve member  44  as shown in FIG.  6 . The sleeve member  44  has a spring supporting surface  46  of a diameter D- 1  and a pin supporting surface  47  of a diameter D- 2  which is greater than the diameter D- 1  of the spring supporting surface providing a shoulder  48  against which the spring  28 ′ abuts. A cross pin  30 ′ extends through an opening  50  in the sleeve member  44  and through an opening  52  in the valve stem  32 ′. Compressed air is supplied through air passage  24 ′ and air vents  26 ′ in the valve seat  34 ′. The valve body member  22 ′ may have threads  54  in flange  56  for receiving threads of a bolt  58  extending through the first mold half  14 ′ and engaging the valve body threads  54 . 
     As shown in FIG. 5, the valve stem hole  52  is drilled through the stem receiving the cross pin  30 ′ which also extends through a hole  59  in the sleeve member  44 . 
     As shown in FIG. 3, the valve body member  22 ′ may have four air vents  26 ′ positioned radially inward of the outer diameter of the poppet valve seat  34 ′. A bearing surface may be provided in a cylindrical opening  62  of the valve body member  22 ′ for receiving the valve stem  32 ′. 
     Preferably the material for the sleeve member  44  is  420  stainless steel. With reference to FIG. 6, the sleeve member of this embodiment has the following dimensions: a diameter D- 1  of 0.099 inches (0.25 cm) and a diameter D- 2  of 0.141 inches (0.35 cm). The length L- 1  of the spring supporting surface  46  is 0.085 inches (0.21 cm) and the total length of the sleeve member  44  is 0.155 inches (0.39 cm). The diameter of the hole  49  for the pin  50  is 0.039 inches (0.09 cm). 
     Referring to FIG. 4, the valve body member  22 ′ has a cylindrical opening  62  for receiving the sleeve member  44  and the spring  28 ′. This opening  62  has a diameter of 0.145 inches (0.36 cm). Opposing slots  64  in the flange  56  provide access to the air passage  24  and permit movement of the cross pin  30 ′. 
     In operation the poppet valve assembly  40  is held in the closed position shown in FIG. 2 by the spring  28 ′ engaging the shoulder  48  of the sleeve member  44 . Movement of the sleeve member  44  on the valve stem  32 ′ is prevented by cross pin  30 ′ extending through the hole  52  in the valve stem  32 ′ and the hole  50  in the sleeve member. The molded object  18 ′ is formed between the first mold half  14 ′ and second mold half  16 ′ by injection or other means well known to those skilled in the art. The second mold half  16 ′ is then moved away from the first mold half  14 ′ and compressed air communicated through the air passage  24 ′ and the air vents  26 ′ to the poppet valve member  20 ′ urging the poppet valve member against the molded object  18 ′ and separating the object from the mold face  12 ′ by injecting air between the object and the mold face. The spring  28 ′ is compressed between the shoulder  48  and the valve body member  22 ′ by the valve stem  32 ′ urging the cross pin  30 ′ towards the poppet valve member  20 ′. During this operation the valve stem  32 ′ is maintained in a coaxial relationship by the sleeve member  44  so that after ejecting the molded object  18 ′ the poppet valve member  20 ′ will be seated coaxially in the valve seat  34 ′. Also with this construction the forces resulting from compression of the spring  28 ′ are transferred to the cross pin  30 ′ in shear by the sleeve member  44  and damage to the pin by bending is avoided. 
     While a certain representative embodiment and details have been shown for the purpose of illustrating the invention, it will be apparent to those skilled in the art that various changes and modifications may be made therein with out departing from the spirit or scope of the invention.