GB1574216A

GB1574216A - Means for securing members to shafts in rotary assemblies

Info

Publication number: GB1574216A
Application number: GB10651/77A
Authority: GB
Original assignee: Keystone International Holdings Corp; Keystone International Inc
Current assignee: Keystone International Holdings Corp; Tyco Flow Control Inc
Priority date: 1976-03-12
Filing date: 1977-03-14
Publication date: 1980-09-03
Also published as: DE2710104A1; AU515047B2; SE420860B; JPS52135422A; FR2343947B1; SE7702689L; AU2318977A; CA1056791A; IT1077488B; MX144213A; NL7702644A; BR7701510A; FR2343947A1

Description

(54) MEANS FOR SECURING MEMBERS TO SHAFTS IN ROTARY ASSEMBLIES (71) We, KEYSTONE INTERNATIONAL INC., a corporation organized and existing undr the laws of the State of Texas, United States of America, of P.O. Box 40010, Houston, Texas 77040, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following state ment-: The present invention pertains to rotary assemblies wherein 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 valves having rotary valve elements mounted on shaft members or trunnions which are journaled in a valve body.

While the invention is particularly suited to disc-type valves, it may also be used with other types of rotary valves such 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 operated by a handle or valve actuator.

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 of the connections between 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 consequent reduction in torque-carrying capacity of the shaft members. It is also desirable that the connections be designed so that the shaft members, valve element, and associated parts can be easily and inexpensively manufactured with conventional equipment and so that the apparatus can be easily assembled and disassembled.

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 pinned type of connection, the pin extends through bores in the shaft member and valve element respectively. It is necessary not only that these bore be perfectly aligned but also that there be an extremely tight 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-sectional configuration of one section of the shaft to make it square, hexagonal, double D, or the like. Alternatively, 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 crosssectional area. This in turn drastically reduces the torsional strength or torque carrying capacity of the shaft member. For 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.

Another disadvantage of both pinned and keyed connections is that, even when the necessary tight fits are provided, wear of the parts during use of the valve eventually begins to allow the undesirable play which the tight fits prevented.

Thus, in th epast, there has been no simple and inexpensive manner of securing the valve element or other rotary 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 develops due to wearing of the engaged parts.

According to the present invention, there is provided 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 sai 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 substantially 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.

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 undesirable play which develops can be eliminated by a simple adjustment of the torque transmission member.

Relative rotation of the valve element and shaft is prvented by the firm engagement of the flat and the end ace, 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 valves. Yet rotative play between the flat and the end face is prevented.

Because the flat is continuous with the cylindrical portion of the shaft's outer surface at the side edges, the end face of the torque transmission 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 positioning 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.

However, axial play, like rotative play, is prevented by the compressive forces urging the end surface of the torque transmission member against the flat.

Additionally the machining of the flat on the shaft reduces the cross section of this section of the shaft much less than would 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 torque transmission extends 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 biting 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. For example, the arc of the cylindrical portion of the outer surface of the shaft subtended by the flat may be approximately 900.

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 the torque transmission member into tighter engagement with the flat. In the preferred embodiment this is accomplished by having the torque-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 an object of the invention to provide a rotary assembly having improved means for securing a shaft to the rotary element for joint rotation.

An embodiment of the invention will now be described by way of example, with reference to the accompanying drawing in which: Figure 1 is an elevational view of a valve assembly in accord with the present invention.

Figure 2 is a cross-sectional view of the assembly of Figure 1 taken on lines 2-2 thereof.

Figure 3 is an enlarged fragmentary sectional view of the torque transmission member and shaft taken on lines 3-3 of Figure 1.

Figure 4 is an enlarged fragmentary sectional view of the torque transmission member and shaft taken on lines 4-4 of Figure 1.

Figure 5 is a fragmentary view taken on line 5-5 of Figure 4.

Referring now to the drawings, the invention is illustrated as incorporated in a disc or butterfly type valve assembly 10 although it will be understood that the invention could also be applied to ball valve assemblies and numerous other types of rotary assemblies in which a rotary element is secured to a shaft rotatably mounted in or on a stationary body.

The assembly 10 comprises a stationary valve body 12 having a cylindrical bore 14 therethrough. A generally cylindrical elastomeric valve seat 16 is disposed in the bore 14 and defines a cylindrical flowway 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 flowway 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 with 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 36 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. Shaft 36 has a valve stem portion 36a extending axially outwardly through the upper boss 26 and including wrench surfaces 35b 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 rotatably 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 fully 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 therethrough coaxial with bore 30. Bore 52 registers 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 and a closure plate 64 extends across said outer end of boss 28 and is fixed 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 (Figure 1) by which they can be advanced or retracted in their respective bores by a wrench or the like.

Shaft 58 and torque transmission member 70 are shown in greater detail in Figures 3, 4 and 5, and it should be understood that torque transmission member 48 and the adjacent part of the 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 Figure 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 extends laterally beyond the side edges 82 as seen in Figures 3 and 5.

As best seen in Figure 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 diameter 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 close 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 58. As shown in Figures 4 and 5, the end face 80 of the torque transmission member lies between the end edges 84 of the flat 72.The difference between the length L and diameter D may allow some axial adjustment between the member 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 abutment 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 member 70. This firm abutment also provides axial restraint of the shaft 58 with respect to disc 20. To enhance the torque transmission characteristics, distribute the torque 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 0 in Figure 3. Thus a relatively large abutment area is provided on the flat.The diameter D of the end face 80 of the torque 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.

Furthermore 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 Figure 5, this chord length C is over half as great 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. Yet the tight compressive engagement of these members prevents rotative and axial 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.

WHAT WE CLAIM IS: 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

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. Shaft 58 and torque transmission member 70 are shown in greater detail in Figures 3, 4 and 5, and it should be understood that torque transmission member 48 and the adjacent part of the 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 Figure 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 extends laterally beyond the side edges 82 as seen in Figures 3 and 5. As best seen in Figure 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 diameter 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 close 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 58. As shown in Figures 4 and 5, the end face 80 of the torque transmission member lies between the end edges 84 of the flat 72.The difference between the length L and diameter D may allow some axial adjustment between the member 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 abutment 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 member 70. This firm abutment also provides axial restraint of the shaft 58 with respect to disc 20. To enhance the torque transmission characteristics, distribute the torque 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 0 in Figure 3. Thus a relatively large abutment area is provided on the flat.The diameter D of the end face 80 of the torque 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. Furthermore 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 Figure 5, this chord length C is over half as great 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. Yet the tight compressive engagement of these members prevents rotative and axial 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. WHAT WE CLAIM IS:

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 interupted 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 substantially 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. An assembly as claimed in 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. An assembly as claimed in claim 1 or 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. An assembly as claimed in claim 3 wherein said one flat subtends an arc of approximately 900 on said cylindrical main portion of said outer surface of said first shaft member.

5. An assembly as claimed in any of claims 1 to 4, wherein said one torque transmission member is threaded into said second bore.

6. An assembly as claimed in any preceding claim 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. An assembly as claimed in any of claims 1 to 6, wherein said body is a valve body having a flowway therethrough and said rotary element is a valve element disposed in said flowway.

8. An assembly as claimed in claim 7 wherein said valve element is a disc-type element.

9. An assembly as claimed in claim 7 or 8, wherein said first shaft member includes a valve stem portion extending outwardly through said valve body.

10. A rotary assembly substantially as hereinbefore described with reference to the accompanying drawing.