CA1056791A - Rotary assembly - Google Patents

Abstract

ROTARY ASSEMBLY

Abstract of the Disclosure A rotary assembly having a stationary body, a rotary element disposed adjacent the body, and a shaft rotatably mounted in the body and extending into a first bore in the rotary element. A second bore in the rotary element inter-sects the first bore. The shaft has an outer surface comprising a cylindrical main portion interrupted by a flat in register with the second bore. A cylindrical torque transmission member is disposed in the second bore and has a flat circular end face compressively urged into abuttment with the flat on the shaft.
The flat has circumferentially spaced side edges and axially spaced end edges and is continuous with the cylindrical main portion of the outer surface at the side edges and spaced inwardly from the cylindrical main portion at the end edges.
The diameter of the end face of the torque transmission member extends laterally beyond the side edges but lies between the end edges of the flat.

Description

~ac};~round of the ~nvention 1 Ii~ld of the Invcntion _ __ _ The present invention pertains to rotar~ assemblies ~herein a rotatable member is affixed to a shaft or the like which in turn is rotatably mounted in a housing or body. In particular, the invention pertains to valvcs having rotary valve el~ments mounted on shaft members or trunnions which are jour-naled in a valve body.
While the invention is particularly suited to disc-type valves, it may also he used with other types of rotaryvalves ~uch as ball valves as well as with numerous other rotary assemblies. In valve assemblies for example, the valve element usually has a pair of coaxial bores extending radially therein and opposite each other on the valve element. Shaft members or trunnions extend into each of these bores and are rotatably mounted in the valve body. Conveniently, one of the shaft members is usually longer than the other so that it can extend outwardly through the valve body to provide a valve stem portion which can be op2rated by a handle or valve actuator.
~0 It is necessary to fix the valve element with respect to the shaft members so that they will rotate as a unit when the stem is turned.
The performance of such valves is, to a great extent, determined by the quality and integrity OL the connections be~ween the shaft members and the valve element. These connections should be capable of transmitting torque loads of high magnitude in either direction with minimum rotative and axial play between the shaft members and valve element. Ideally the connections should provide for such torque transmission while minimizing the conse-0 quent reduction in torque carrying capacity of the shaft-members.

It is also desirable that the connections be designed so that the ~haft members, valve element, and associated parts can be easil~
ard inexpensively manufactured with conventional equipment ~nd so that the apparatus can be easily assembled and disassembled.

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? __ Descr_pt_on_of_the Prior ~rt In conventional trunnion mounted valve elements, the trunnions or shaft members are usually fixed to the valve element either by pins or by some type of key. In the pinlled type of connection, the pin extends throuc3h bores in the shaft member and valve element respectively. It is necessary not only that these bores be perfectly aligned but also that there be an extremely tiyht fit between the pin and the bores. Thus very close tolerances and/or machining of the parts during assembly are required resulting in high cost and inconvenience in the use of the pinned type of connection.
In the keyed type of connection, on the other hand, the shaft member must be machined to receive the key. This may involve altering the circular cross-sectio~al configura-tion of one section of the shaft to make it square, hexagonal, double D, or the like.
Alternative, a slot may be cut in the shaft member to receive the key. In either case, a substantial amount of metal is removed from the shaft member in the machined section diminishing its cross-sectional area. This in turn drastically reduces the torsional ~0 strengih or torque carrying capacity of the shaft member. ~or example, by machining a shaft section from circular to square cross-sectional configuration, its torsional strength is reduced by over sixty percent, Furthermore, as in the case of the pinned type of connection, the keyed connection requires close tolerances for satisfactory performance. This in turn necessitates complex manufacturing processes resulting in high manufacturing costs.
Furthermore, conventional keyed connections only prevent relative rotation between the shaft members and valve element and do not provide axial restraint. Consequently, additional means must be provided for fixing the shaft members axially with respect to the valve element thus further raising the cost of manufacture.

105~7~1 An~ther disadvantage of both pinned and keyed connections is that, even when the necessary tight fits are provided, wear o~
the parts during use of the valve eventaully begins to allow the undesirable play which the tight fits prevented.
Thus, in the past, there has been no simple and in-expensive manner of securing the valve element or other ro-tary element to the shafts or trunnions on which it is mounted so that undesirable play is prevented. Furthermore, there has been no satisfactory manner for easily eliminating such play as it 0 de~elops due to wearing of ihe engaged parts~
Summary of the Invention The present invention provides a simple means for securing a rotary element to one or more shaft members for joint rotation. The invention makes use of a torque transmission member compressively urged against a flat on the shaft member and eliminates much of the need for machining of various parts to close tolerances. Yet the assembly of the invention prevents undesirable play between the valve element and shafts. As the parts of the assembly wear,, any undesirab-e play which develops can be eliminated by a simple adjustment of the torque trans-mission member.
In accord with the present invention, the rotary element has a first shaft-receiving bore and a second bore transverse to and intersecting the first bore. The outer surface of the shaft in turn has a cylindrical main portion interrupted by a flat in register with this second bore. The flat has circumferentially spaced side edges and is continuous with the remaining cylindrical portion of the shaft's outer surface at these edges. The flat also has axially spaced end edges at which the flat is spaced inwardly or recessed from the remaining cylindrical portion of the outer surface.

~OS~7~1 ~ cylindrical torque translnis.iollTnembcr is disposed in the second bore of the valve element. The torque transmission member has a substantially flat, circular end surface which lies parallel to and abuts the flat. The diameter of the end face is greater than the distance between the side edges of the fla-t but less than or substantially equal to the distance between the end ed~es so that the end face extends laterally beyond the side edges of the flat but lies between its end edges. The torque transmission member is retained in the second bore as by threading so that it is compressively urged toward the flat.
Relative ro~ation of the valve element and shafL is prevented by the finm engagement of the flat and the end face, effected by the compressive forces on the torque transmission member~ Thus there is no need for a keyway, pin receiving bore, or generally radially extending torque transmission surfaces on the shaft, and the flat and end face do not extend radially with respect to the shaft. This in turn eliminates the need for the close tolerances which are required in prior art ~alves. Yet rotative play between the flat and the end face is prevented.
Because the flat is continuous with cylindrical portion of thè shaft's outer surface at the side edges, the end face of the key member can still abut the flat regardless of variations in the lateral dimensions of the two. Accordingly, close tolerances are not required in the lateral direction.
Since axial posiLioning is not especially critical, the distance between the end edges of the flat may be made larger than the maximum diameter of the end face whereby close tolerances in the axial direction are eliminated, and the parts of the valve-are easier to align and assemble.

105679i Ilo~evcr, a~;ial play, li~e rotative play, is prcventedby the compressive force5 ulying the end surface of the to~que transmission member a<Jainst the flat.
Additionally the machining of the flat on the shaft reduces the cross section of this section of the shaft much less than wou]d machining a conventional keyway or the like so that the reduction in the torque carrying capacity of the shaft is minimized.
The fact that the end face of the key member extends I0 laterally beyond the side edges of the flat provides a large area on which the side edges can bear when transmitting torque to the key member and prevents the edge of the end face of the key member from bi~ing into the flat. The end face is preferably circular and the flat rectangular with the end face sized so that the side edges of the flat intersect the end face in chords of substantial length with respect to the end face diameter.
The contact area of the flat and the end face of the torque transmission member is preferably relatively large.
F~r example, the arc of the cylindrical portion of the outer surface of the shaft subtended by the flat may be approximately 90.
If, due to wearing of the parts during use, some play should develop between the shaft and the rotary element, this can be easily and quickly corrected by urging ihe torque transmission member into tighter engagement with the flat. In the preferred embodiment this is accomplished by having the tor~ue-transmission member threaded intO the second bore permitting easy adjustment of the compressive force between the flat and the end face of the key member.
It is thus a principal object of the invention to provide a rotary assembly having improved means for securing a shaft to the rotary element for joint rotation.

lt~S6791 it is ano~her object o~ the invention to proyide a me~ans for mounting a rotary element on a rotary shaft ernploying a torque transmission m~mber compressively urged agaillst a flat on the shaft.
Another object of the invention is to provide a means for preventing rotative and/or axial play between a rotary element and shaft without the need for close tolerances between the shaft and a torque transmission member.
Still another object of the invention is to provide a simple means for eliminating play which may develop in a rotary assembly due to wearing of the interengaged parts.
A further object of the present invention is to provide an improved valve ass~mbly having a rotatable valve element.
Still further objects, features, and advantages of the present invention will be made apparent by the following description of the preferred embodiments, the drawings, ana the claims.

Brief Description of the Drawings Fig. 1 is an elevational view of a valve assembly in accord with the present invention.
Fig. 2 is a cross-sectional view of the assembly of Fig. 1 taken on lines 1-1 thereof.
Fig. 3 is an enlarged fragmentary sectional ~iew of the torque transmission member and shaft taken on lines 3-3 of Fig. 1.
Fig. 4 is an enlarged fragmentary sectional view of the-torque transmission member and shaft taken on lines 4-4 of Fig. 1.
Fig. 5 is a fragmentary vie~ taken on lines 5-5 of Fig. 4.

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Description of the Preferred Embodiments P~eferring no~ to tlle drawings, the invention is illustrated as incorporated in a disc or butterfly type valve assembly 10 although it will be ~nderstood that the invention could also be applied to ba~l valve assemblies and numerous other types of rotary assemblies in which a rotary element is secured to a shaEt rotatably moun~ed in or on a stationary body.
The assembly 10 comprises a stationary valve body 12 having a cylindrical bore 14 ~herethrough. A generally cylindrical elastomeric valve seat 16 is disposed in the bore 14 and defines a cylindrical flo~ay 18 through the valve body 12. Seat 16 includes a metal reinforcing ring 17 embedded in the elastomer. A disc-type valve element 20 is disposed in the flo~ay 18. Seat 16 seals against valve element 20 when the latter is in its closed position as shown.
Valve body 12 includes flanges 22 having bores 24 therethrough for mounting the valve between a pair of flange fittings in a pipe line or the like in a manner well known in the art.
The valve body 12 further comprises upper and lower bosses 26 and 28 respectively extending radially outwardly with respect to the axis of the flowway 18. Upper boss 26 has a bore 30 therethrough, also extending radially with respect to the axis of flowway 18 and registering ~ith an aperture 32 through the valve seat 16. Valve element 20 has a first bore 34 therein registering with aperture 32 and bore 30. A first shaft or trunnion 35 extends through bore 30 and aperture 32 and into bore 34. As used herein, terms such as "radial", "axial", "circumferential", etc. will be construed with respect to the shaft 36 unless otherwise noted.

Sh~t 36 has a valve stem portion 36a extending axially outwardly through the upper hoss 2~ and including wrench surfaces 36b by which the shaft 36 may be engaged and rotated by an actuator, valve handle, or the like. Upper boss 26 has an annular radially extending flange 38 at its outer end to which such actuator, handle, or the like can be attached. A
bushing ring 40 is disposed in the outer end of bore 30 to ro-tatably mount shaft 36 in bore 30. O-rings 42 and 44 disposed in respective inner and outer grooves in the bushing 40 form seals between shaft 36 and boss 26 respectively Disc 20 has a second bore 46 therein transverse to and intersecting bore 34. A torque transmission member 48 (to be described more fùlly below) is disposed in bore 46 and abuts a flat 50 on the shaft 36 registering with bore 46.
Lower boss 28 has a longitudinal bore 52 there-th~ough coaxial with bore 30. Bore 52 re~isters: with an aperture 54 through seat 16 and a third bore 56 in disc 20 opposite bore 34. A shaft 58 extends through bore 52 and aperture 54 and into bore 56. Shaft 58 is sealed with respect to boss 28 by an O-ring 60 and is journaled in a bearing 62 of Teflon or the like. The outer end of shaft 58 is flush with the outer end of boss 28 by screws 66 to retain shaft 58 in place.
Disc 20 has a fourth bore 68 therein transverse to and intersecting bore 56. A torque transmission member 70, disposed in bore 68 abuts a flat 72 on shaft 58. Each of the torque transmission members 48 and 70 is in the form of a generally cylindrical screw threaded into its respective bore 46 or 68. The torque transmission members 48 and 70 have respective sockets 74 and 76 by which they can be advanced or retracted in their respective bores by a wrench or the like.

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_g_ Sh~ft 58 and torquc transrnisslon member 70 are shown in greater detail in Figs. ~, 4, and 5, and it should be understood that torque transmission member 48 and the adjacent part of shaft 36 are substantially identical The torque transmission member 70 has a flat circular end face 80 of diameter D. The shaft 58 has an outer surface comprising a cylindrical main portion 78 interrupted by the flat 72.
Flat 72 is rectangular, having circumferentially spaced side edges 82 and axially spaced end edges 84. As shown in Fig. 3, the flat 72 is continuous with the cylindrical portion 78 of the outer surface of the shaft at the side edges 82. Thus, the end face 80 of the torque transmission member 70 can lie parallel to and abut the flat 72 even though its diameter D is greater than the width W of the flat, i.e. the distance between side edges 82. Accordingly, the end face 80 ex~ends laterally beyond the side edges 82 as seen in Figs. 3 and 5.
As best seen in Fig. 4, the end edges 84 of the flat 72 are spaced inwardly from the cylindrical portion 78 of the outer surface of the shaft. The length L of the flat 72, i.e. the distance between the end edges 84 must therefore be at least as great as the aiameter D of the end face 80 in order to allow the end face 80 to abut the flat 72.
However, in the preferred embodiment shown length L is greater than diameter D by an amount substantially greater than that which would be allowable by ordinary closè tolerances. ¦This eliminates the need for machining to such tolerances and also allows the threads of the torque transmission member 70 to extend all the way to its end face 80 even though member 70 is not threadedly received in the shaft 5g. -As shown in Figs. 4 and 5, the end face 80 of the torque transmission member lies between the end edges 84 of the flat 72. The lOS~;791 di~ference between len~h L and ~liari~eter D rnay allow some axial adjustment bet~een the mem~fL 70 and shaft 58 during assembly.
The spacing of end edges 84 from cylindrical portion 78 provides stop shoulders 86 engageable with the torque transmission member 70 to prevent excessive axial movement.
As the torque transmission member 70 is advanced into its bore 68, it is compressively urged toward the flat 72 This effects a firm abut~ent of the end face 80 and flat 72 so that torque will be transmitted between the shaft 58 and disc 20 via the torque transmission r,~mber 70. This firm abutment also provides axial restraint of shaft 58 with respect to disc 20. To enhance the torque transmissiOn characteristics, distribute the torgue load, and prevent damage to the shaft 58 or torque transmission member 70, the width W-of flat 72 is made quite large. In the preferred embodiment shown, the flat 72 subtends an arc of 90 on the cylindrical portion 78 of the outer surface of the shaft as indicated at e in Fig. 3. Thus a relatively large abutment area is provided on the flat. The diameter D of the end face 80 af the torgue transmission member is then made even larger than width W so that end face 80 extends laterally beyond side edges 82.
This helps to prevent member 70 from biting into flat 72.¦ Further-more the lateral extensiOn is great enough for side edges 82 to intersect end face 80 in chords of substantial length with respect to diameter D. As seen in Fig. 5, this chord length C is over half as gxeat as diameter D.¦ Thus the chords of intersection represent extended contact areas over which the major part of the torque load is distributed, and this helps to prevent flat 72 from biting into end face 80 at side edges 82.
It can thus be seen that the members 48 and 70 and respective abutting flats 50 and 72 provide for torque transmission without the need for machining of these parts to close tolerances.

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Yet the tight compressive ongagement of these members prevents rotative and a~ial play therebetween and, accordingly, between the shafts 36 and 58 and the disc 20. Furthermore, if some play should develop as the valve is used and becomes worn, this can easily be corrected by simply advancing the members 48 and 70 in their respective bores 46 and 68 toward their respective flats 50 and 72.
It will be appreciated that many modifications of the preferred embodiment shown can be made without departing from the spirit of the invention. As mentioned above, the invention can be used with types of rotary assemblies other than disc valves. The torque transmission member or members of any assembly can be in the form of other types of elements than - threaded members, and the means for compressively urging them against their flats can be other than threaded engagement with the rotary element. The configuration and dimensions of the flats could also be changed. Accordingly, it is intended that the scope of the invention be limited only by the claims which follow.

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Claims (9)

Claims

1. In a rotary assembly comprising a stationary body, a rotary element disposed adjacent said body and having a first bore therein, and a first shaft member rotatably mounted in said body and extending into said first bore in said element, the improvement comprising:
said element further having a second bore therein transverse to and intersecting said first bore;
said first shaft member having an outer surface comprising a generally cylindrical main portion interrupted by one flat, said one flat being in register with said second bore and having circumferentially spaced side edges and axially spaced end edges, said one flat being continuous with said cylindrical main portion at said side edges and spaced inwardly from said cylindrical main portion at said end edges;
one generally cylindrical torque transmission member disposed in said second bore and having a substantially flat circular end face parallel to and abutting said one flat, the diameter of said end face being greater than the distance between said side edges of said flat and less than or sub-stantially equal to the distance between said end edges of said flat whereby said end face extends laterally beyond said side edges but lies between said end edges;
and means for compressively urging said one torque transmission member toward said one flat.

2. The assembly of claim 1 wherein said one flat is generally rectangular, and the diameter of said end face is less than the distance between said end edges of said one flat.

3. The assembly of claim 2 wherein said side edges of said one flat intersect said end face along respective chords of said end face of substantial length with respect to the diameter of said end face.

4. The assembly of claim 3 wherein said one flat subtends an arc of approximately 90° on said cylindrical main portion of said outer surface of said first shaft member.

5. The assembly of claim 1 wherein said one torque transmission member is threaded into said second bore.

6. The assembly of claim 1 wherein said element further has a third bore therein coaxial with and opposite from said first bore and a fourth bore therein transverse to and intersecting said third bore, said assembly further comprising a second shaft member rotatably mounted in said body and extending into said third bore and having another said flat in register with said fourth bore, another said torque transmission member disposed in said fourth bore, and another means for compressively urging said other torque transmission member toward said other flat.

7. The assembly of claim 1 wherein said body is a valve body having a flowway therethrough and said rotary element is a valve element disposed in said flowway.

8. The assembly of claim 7 wherein said valve element is a disc-type element.

9. The assembly of claim 7 wherein said first shaft member includes a valve stem portion extending outwardly through said valve body.