Background of the Invention

A stem of a rotatable valve member, such as a butterfly valve, is weakened in certain areas such as, for example, the areas where pins secure the butterfly valve member to the stem. If an unusually high torque is placed on the stem, shear failure of the stem may occur and fluid pres¬ sure in the valve body under certain conditions may tend to urge or blow the sheared stem out of the bore resulting in possible injury to an operator of the valve. It is highly desirable that any device to prevent the blow¬ out of a sheared stem be easi ly assembled within the bore of the valve body. Summary of the Invention

The present invention is directed general ly to a butterfly valve hav¬ ing a body with a bore therein receiving a stem secured to a butterfly valve member. More specifical ly, the invention relates to means mounted within the bore to restrain outward movement of the stem from the body in the event of a shearing or breaking of the stem . The retaining means comprises a stop member on the stem which extends outwardly from the outer periphery of the stem, and a tapered support ring mounted in a groove in the bore adjacent the stem member to engage the stop member and restrain any out¬ ward movement of the stem . The tapered support ring is held in the groove by a split retainer ring which is easily inserted within the groove between a tapered outer periphery of the support ring and an opposed tapered groove surface. The split retainer ring expands outwardly to hold the support ring in position against the tapered groove surface thereby to prevent any outward movement of the stem. Description of the Invention

Fig. 1 is a sectional view of a butterfly valve structure which incor¬ porates the stem retention device comprising the present invention;

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Fig. 2 is an enlarged fragment of Fig. 1 illustrating the stem retentio device within the stem bore;

Fig. 3 is an enlarged section of the stem retention device of Figs. 1- showing the split retainer ring prior to insertion;

Fig. 4 is an enlarged section of the groove in the bore of the valve body with the retainer ring and support ring of the retention device shown in section removed from the groove;

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Fig. 5 is ^" α top plan of the split retainer ring; and Fig. 6 is a top plan taken generally along line 6-6 of Fig. 1 . Referring now to the drawings for a better understanding of the in¬ vention, and more particularly to . Fig. 1 , the butterfly valve structure generally indicated at 10 comprises a body 12 having a flow passage 14 therethrough. A butterfly valve disc indicated generally at 16 is mounted within the flow passage for movement between open and closed positions and comprises a front face 1 8, a rear face 20, and an outer peripheral sealing surface 22 extending about the outer periphery of valve disc 16 to form a generally spherical sealing surface. Rear face 20 has an integral sleeve 24 and a shaft or stem 26 fitting within sleeve 24 is secured thereto by suitable pins 28 to connect valve disc 16 for rotation with stem 26. A handle 30 is secured to the outer end of stem 26 for manual gripping and rotation of stem 26. A seat assembly generally indicated at 32 has a resilient seal element

34 which is adapted to engage in seal ing relation the adjacent sealing sur¬ face 22 of butterfly valve disc 16. A retainer plate 36 is secured to body 12 to hold seat assembly 34 in position . Body 12 has a bore 38 receiving stem 26, A sleeve bearing 40 is positioned within bore 38 at the upper and lower ends of valve disc 16. Bore 38 has an enlarged intermediate bore portion 42. Retainer pins 44 are driven within blind openings 46 in stem 26 and the ends of pins 44 extend outwardly from the outer periphery of stem 26 within chamber 48 formed by intermediate bore portion 42. A large diameter end bore portion 49 receives a plurality of packing rings 51 therein which are supported on a metall ic end ring 50. A gland ring 52 fits around stem 26 against packing rings 51 and extends upwardly into a cutout portion of body 12 indicated at 12A. A gland retainer plate 53 fits over ring 52 and is retained by nuts 54 on studs 55 which are mounted in body 12. Plate 53 may be adjusted by nuts 54 to control the compressϊve forces exerted against packing rings 51 by gland ring 52.

As shown particularly in Fig. 4, an annular groove indicated generally at 56 is provided at the juncture of large diameter bore portion 49 and intermediate bore portion 42. Groove 56 defines a lower shoulder or abutment 58, an outer peripheral wall surface 60 and an upper inclined or tapered shoulder defining surface 62 of a frusto- conical shape. A wedge

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support ring indicated generally at 64 fits about stem 26 and has an outer peripheral surface 66 with a frusto- conical or tapered end surface 68. The inner peripheral surface of ring 64 is indicated at 69. Surface 68 is ar¬ ranged at around a thirty degree angle with respect to the longitudinal axis of stem 26 and surface 66. Tapered surface 62 defining groove 56 is ar¬ ranged at around a forty-five degree angle with respect to the cylindrical surface defining the adjacent bore 49. A split retainer ring 70 is of a circular cross section and is positioned between tapered surfaces 62 and 68 de fining groove 56 and wedge ring 64. Pin 44, wedge ring 64, and spl it retainer ring 70 in combination with groove 56 define the retaining means for holding stem 26 within bore 38. In the event of any shearing of stem 26 below pin 44, fluid pressure from flow passage 14 tends to urge the upper sheared portion of the stem from bor 38, the ends of pin 44 wil l contact the lower surface of wedge ring 64 and urge wedge ring 64 upwardly against split ring 70. As shown in Fig. 3, split retainer ring 70 is easily inserted between inclined surfaces 62 and 68. Since surface 68 diverges from the longitudinal axis of stem 26 less than the divergence of surface 62, upward movement of support ring 64 tightly urges split ring 70 against surface 62 thereby to limit upward movement of ring 64. Thus, pin 44 is restrained from outward movement by wedge ring 64 to preven stem 26 from being blown out of valve body 12 upon any malfunctioning or shearing of valve stem 26.

The stem retaining device may be easily assembled within the bore of the valve body as wedge ring 64 can be inserted from the upper end of the body and be seated on shoulder 58. Then, split ring 70 may be inserted between surfaces 62 and 68 to hold wedge ring 64 in position. End packing ring 50 separates packing rings 51 from wedge ring 64 and may be inserted within the bore along with packing rings 51 . Then, gland ring 52 and re¬ tainer plate 53 are added to hold packing rings 51 and the retaining means within the bore. Nuts 54 are threaded on studs 55 to provide a predeter¬ mined compressϊve loading of packing rings 51 .

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Tapered surfaces 62 and 68 may be formed, if desired, of different angles with respect to the longitudinal axis of stem 26 and function in a satisfactory manner so long as surface 62 is disposed at an angle greater than the inclination of surface 68 wit respect to the longitudinal axis of stem 26 to insure that ring 70 is wedged tightly between surfaces 62 and 68. For ex¬ ample, surface 62 could be positioned between around thirty-five degrees (35°) and ninety degrees (90°) with respect to the longitudinal axis of stem 26 and function in a satisfactory manner.

It is to be understood that means other than pins 44 could be provided on stem 26 to engage ring 64 such as an annular shoulder, or separate snap ring in an annular groove in stem 26, for example.