ADJUSTABLE TORQUE LIMITING VALVE HANDLE

Abstract: Torque-limiting valve handle (10) having one or more independently adjustable spring loaded balls (48) urged into contact with cavities (60) formed in the inside surface of a housing (24) adapted for external manual engagement. The adjustment of the torque limit of the valve handle by set screw (52) is protected from tampering or inadvertent modification by unauthorized personnel by a back plate (34) which may only be removed when the entire valve handle is disassembled.

Description: ADJUSTABLE TORQUE LIMITING VALVE HANDLE Field of the Invention This invention relates generally to valve handles and more particularly to torque limiting valve handles. Background of the Invention Torque limiting valve handles are in wide use in petrochemical or other industries wherein hazardous and/or combustable materials are involved. The valve handles are equipped with means for limiting the torque that can be manually applied through the valve stem to prevent damage to the valve and possible accidents involving the hazar¬ dous materials. U.S. Patent No. 3,441,115, which issued to Gunther, shows such a torque limiting valve handle having a handle housing threadedly engaged with a cap portion. A ball retainer is adapted for mounting on a valve stem and is constrained between the housing and cap portion. A plurality of balls are carried within longitudinal openings in the ball retainer and urged by a stack of Belleville washers into engagement with multiple depressions in an inner surface of the handle housing. The valve handle will rotate as a unit when a torque is applied below a predetermined level. When a torque is applied above the predetermined level, such as when the valve is in a fully open or closed position, the force of the Belleville washers is overcome and the balls are SUBSTITUTE SHEET forced out of engagement with the openings. This allows the handle housing and cap portion to rotate independently of the ball retainer and valve stem and prevents excessive torque from being applied to the valve. Adjustment of the force exerted by the Belleville washers is provided by relative rotation of the handle housing with respect to the cap portion, and secured by two externally accessible set screws. However, Gunther and similar conventional designs suffer from several limitations. First, since the adjustment means is externally accessible, unauthorized personnel are able to change the level of force exerted by the Belleville washers to a level which may allow damage to occur to the valve. This may occur intentionally or unintentionally, but in either case, it is undesirable. Secondly, the use of common Belleville washers in contact with all of the ball elements prevents independent adjust¬ ment of the force acting on each of the balls. Therefore, it is a principal feature and advantage of this invention to provide an improved torque limiting valve handle in which adjustment of the torque limit is not possible while the handle is mounted on a valve stem. It is another feature and advantage of this invention to provide an improved torque limiting valve handle in which the force exerted on each of the balls is independently adjustable. Therefore, this and other features and advantages of the invention will become more clearly evident upon a closer examination of the appended specification, drawings, and claims. Brief Description of the Drawings Figure 1A is a side elevational view of the adaptor of the valve handle of this invention; SUBSTITUTE SHEET Figure IB is a top view of the adaptor of the" valve handle of this invention; Figure 1C is a bottom view of the adaptor of the valve handle of this invention; Figure 2A is a top view of the housing of the valve handle of this invention; Figure 2B is an upright cross sectional view of the housing of the valve handle of this invention; Figure 2C is a bottom view of the housing of the valve handle of this invention; Figure 3 is an upright vertical cross-sectional view of the valve handle of this invention; Figure 4 is a horizontal cross-sectional view of the valve handle of this invention along plane 4-4 of Fig. 3; Figure 5 is a bottom view of the valve handle of this invention; Detailed Description of the Invention Referring to Figure 3, the reference numeral 10 generally indicates the valve handle of this invention, which includes adaptor 12, shown in more detail in Figures 1A, IB and 1C and housing 24 shown in more detail in Figs. 2A, 2B and 2C. Adaptor 12 includes concentric opening 14 for insertion of a valve stem (not shown) of a valve and comprises first section 18 nearest the valve (not shown) and cylindrical second section 22 of larger diameter forming both flat end surface 32 facing away from the valve stem and shoulder 23 at the juncture with first section 18. Set screw 20 is engaged within threaded opening 16 formed in first section 18 so as to secure the adaptor to the valve stem when inserted within opening 14. Housing 24 includes a plurality of external longitudinal ribs 26. Alternatively, this surface may be knurled or otherwise suitably adapted for manual engage¬ ment. Housing 24 also includes cup shaped cavity 28 S U B STITUTE SHEET centered around the axis of rotation of the housing, for receiving adaptor 12 so that flat end surface 32 is adjacent surface 30 of the cavity. As is also shown in Fig. 5, back plate 34 is adjacent shoulder 23 of the adaptor and includes rectangular opening 36 in surrounding relation to first portion 18 of the adaptor. Snap ring 28 is positioned within groove 40 of the housing to secure the back plate and the adaptor within cavity 28. Slot 42 is provided in the housing to permit external access to set screw 20 in order to tighten or loosen the set screw and secure or remove the valve handle to the valve -stem. Adaptor 12 includes longitudinal openings 44, only one of which is shown, extending from surface 32 through second section 22. The openings are parallel to the longitudinal axis of rotation of the adaptor in valve stem but are radially offset therefrom. Ball element 48 is carried within the longitudinal opening and is urged along direction 62 towards depressions 60 in surface 30 by a spring or like member 50 which contacts the ball at one end and a set screw 52 engaged within threaded portion 46 of opening 44, at the other end. Adjustment of the force exerted by the spring is enabled by movement of set screw 52 within the opening. If more than one longitudinal opening, spring and ball is provided with the valve handle, the force exerted on each ball is independently adjustable to enable greater control over the composite torque required to disengage the housing from the adaptor. Adaptor 12 also includes one or more openings 54 extending from surface 30 but only partially through second section 22. Within the opening 54 is carried a similar ball element 56 urged outwardly along direction 62 by a spring 58 contacting the ball and the end of the opening. The force exerted by the spring 54 is not adjustable in this case. As shown in Figure 4, the illustrated embodiment of the invention includes one or more ratcheting members 64 slidingly carried within chambers 66 formed in the adaptor transverse to the axis of rotation but offset " therefrom. Spring 68 contained within chamber 66 urges the latching member 64 outwardly along direction 63 towards the interior surface of the cavity 28 of the housing, which includes a plurality of longitudinal grooves 70. Latching member 64 includes a first surface 72 obliquly inclined with respect to direction 63 and a second surface 74 parallel thereto. Torque limited valve handles are frequently used in environments including hazardous or co bustable mater¬ ials which frequently are also corrosive. Accordingly, in the preferred embodiment of this invention, the housing is constructed of a material such as fiberglass and the adaptor and the remainder of the components are constructed of stainless steel, which are unaffected by corrosive substances. In operation, the positions of the various set screws within the openings 44 are positioned in accordance with the spring constants of each spring to establish a predetermined level of torque necessary to disengage the housing from the adaptor. The components of the valve handle are assembled as shown in Fig 3-5. The valve stem (not shown) is inserted into opening 14 of the assembled handle, whereupon set screw 20 is tightened by a suitable tool (not shown) to secure the handle to the valve. The force exerted as the valve handle is rotated in direction 76, little resistance is met, therefore, the housing and adaptor will move in unison because of the engagement of the ball elements 48 and 56 with the depression 60. Because of the presence of the back plate 34, it would not be possible to change the position of set screw 52 without removing the valve handle from the valve stem and disas¬ sembling the handle. During rotation, the sliding contact between the oblique surface 72 and the interior surface of the cavity 28 forces the latching member back into the chamber 66 against the force of the spring 68. As soon as the valve stem reaches either its fully open or closed SUBSTITUTE SHEET position as a result of rotation in direction 76, the ' resistance and the torque required to rotate the valve handle will increase to the point where the ball elements 48 and 56 are forced back into openings 44 and 54 respec¬ tively and out of engagement with depressions 60 so that the housing will rotate independently of the adaptor, preventing further movement of the valve stem. During rotation in direction 78, the housing and adaptor will again move in unison until the valve has reached the opposite point, either fully opened or fully closed, at which point additional resistance will be met. In this case, however, the interaction between the second surface 74 and the groove 70 will prevent the housing from rotating independently of the adaptor even when a torque is applied sufficient to disengage the ball elements from the depressions. Of course, it is within the scope and content of this invention to provide a valve handle without the ratcheting members thereby providing adjustable torque limiting action in both rotational directions. In addition, certain of the springs may be provided with different spring constants to provide greater control over the composite torque necessary to disengage the housing from the adaptor. From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the apparatus and structure. It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims. Because many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense. SUBSTITUTE SHEET

Claims: What is claimed is: • 1. An adjustable torque limiting handle for rotating the stem of a valve to open and close the valve, comprising: a) a cylindrical body adapted for mounting on the valve stem with the longitudinal axis of the body coinciding with the axis or rotation of the stem, and including a flat end facing away from the stem, said body further including at least one longitudinal opening extending from said flat surface through said body and radially spaced apart from said axis of rotation; b) a housing having a cup-shaped cavity for receiving the cylindrical body, and a plurality of depressions formed in said cavity opposite said flat end surface of said body, said detents being concen¬ trically positioned with respect to said axis of rotation and radially aligned with said openings in said body, and further including a rim adapted for manual engagement; c) a backplate mounted on said housing in surrounding relation to said valve stem and adjacent an end of said body oppo¬ site said flat end surface; d) a ball carried within each of said openings in said bodies; e) a spring mounted in each of said openings independently urging said balls outwardly into engagement with said depressions of said housing; and f) means mounted in each of said openings for independently adjusting the force exerted by each of said springs of said SUBSTITUTE SHEET balls, whereby said housing and body will rotate in unison when a torque is applied to the handle below a prede¬ termined level and said housing will rotate independently of said body when a torque above the predetermined level is applied. 2. The handle of Claim 1, wherein at least two of the springs have different spring constants. 3. The handle of Claim 1, further comprising: a plurality of longitudinal grooves formed on the inside of the circum¬ ference of said housing and at least one racheting member carried within a cavity in said cylindrical body, said cavity being aligned transverse to said axis of rotation of said cylindrical body, said racheting member being urged into contact with said grooves by a second spring mounted within said cavities, said racheting member being adapted to permit rotation of said housing with respect to said cylindrical body in one direction when a torque is applied to the handle above a predetermined level, and to prevent such relative rotation in an opposite direction. SUBSTITUTE SHEET

Inventors: PURKEY RICHARD E, WILLIAMS WILLIAM J, PURKEY, RICHARD, E., WILLIAMS, WILLIAM, J.
Applicants: PURKEY RICHARD E, WILLIAMS WILLIAM J, PURKEY, RICHARD, E., WILLIAMS, WILLIAM, J.
Application year: 1985
Main classification: F16K51
IPC codes: F16D7, F16K31