WO1999040348A1

WO1999040348A1 - Shutter for ball valves

Info

Publication number: WO1999040348A1
Application number: PCT/EP1999/000681
Authority: WO
Inventors: Antonio Frezzella
Original assignee: Hydraulic Engineering S.A.
Priority date: 1998-02-06
Filing date: 1999-02-02
Publication date: 1999-08-12

Abstract

Shutter for ball valves, in which shutter at right angle to the flattenings (4, 5) defined by the inlet and outlet ports (4A, 5A) of the through hole (3) are provided two opposite dead shutoff flattenings (8, 9). An upper flattening (13) which has a seat (7) housing the operating rod, and/or a lower flattening (16) are further advantageously provided. In the flattenings (8, 9 and 13, 16) are advantageously provided lightening recesses (10, 11; 18, 21, 22; 19, 23, 24). The body (2) of the shutter (1) made of metal or plastics has an essentially cube-like configuration with rounded edges and corners laying in the imaginary sphere enveloping the shutter body (2).

Description

'Shutter for ball valves'

Description

The invention relates to a shutter for ball valves according to the preamble of claim 1.

Prior art

Ball shutters are known which are constructed from preforms made of metal, for example brass, having a solid or a hollow body and are produced by hot-pressing. The solid preforms are more rigid and allow the machining of an advantageous cylindrical through hole which does not create turbulences in the liquid flowing therethrough. On the other hand said shutters require a high metal expenditure and are, therefore, expensive.

A lightening of said shutters by means of an internal turning allows indeed, on one hand, to reclaim costly metal, but on the other hand said turning also represents an additional cost factor.

The hollow ball shutters are produced starting from a hollow small cylinder by multiphase pressing and are, therefore, rather expensive as to dies and manufacturing times. In said hollow ball shutters also the through hole has internally a spheric configuration which causes turbulences in the liquid flowing therethrough. During the chip- forming machining of the external surface of said hollow shutters, the jaws clamping the shutter exert a necessarily high fastening force which, in turn, produces a certain expansion of the spheroidal body. Due to its inherent elasticity the spheric body after the machining thereof tends to assume its initial form again. This causes a shifting of the external shutter surface from the spheric surface obtained by machining. Nevertheless, in order to reach the necessary sealing action between the ball shutter and the two opposite sealing rings co-operating therewith and which are housed into the valve body, it will, therefore, be necessary to tighten the shutter between said sealing rings what may causes a rather "hard" opening/closing rotary movement of the shutter. Said phenomenon increases when the diameter of the ball shutter increases.

The known ball shutters constructed both from solid balls as well as from hollow balls have two opposite flattenings defining the diameter of the inlet port and outlet port of the through hole, whereas the remaining shutter body has a spheric configuration.

For accomplishing the opening/closing rotational movements of the ball shutters, in the upper part of the latter is provided a known seat housing the internal end of an operating shaft whose external end is connected with an operating member, for example a lever, handle, handwheel or the like.

The known ball shutters move from the open position to the closed position by means of a 90° rotation of the shutter. This results in that during said 90° rotation each sealing ring engages the external surface of a respective ball or sphere segment which, when the shutter is in the closed position, engages the associated sealing rings and is located inside the latter. Therefore, the sliding friction action between ball shutter and sealing ring during the opening/closing movement of the shutter takes place on the outer surface of both said sphere segments which, when the shutter is in the closed position, will be in contact with the liquid in the duct housing the ball valve. In the case of liquids causing incrustations, as for example calcareous deposits in the case of water, said incrustations practically increase the outside diameter of the shutter ball or sphere on both the mentioned sphere segments in contact with the liquid, so that the following opening movement of the valve will become considerably hard and could cause permanent deformations of the shutter as well as abrasions of the sealing rings, what may jeopardize the unobjectionable sealing action thereof. In some cases such incrustations were formed that it was no more possible to rotate the shutter for opening the valve. Ball shutters made of plastics are also known which are produced by injection molding. As to the friction with the sealing rings and the incrustation deposits said plastics ball shutters present the same drawbacks like those of the above discussed ball shutters made of metal. Summary of the invention

The object of the present invention is to provide shutters for ball valves of the type indicated in the preamble of claim 1 which do not present the shortcomings of the prior art shutters .

In a shutter for ball valve comprising a shutter body including a spherical outer surface, two opposite flattenings defining the inlet and outlet ports of the through hole of said shutter, as well as a seat for housing an operating rod, the above stated object is achieved according to the present invention by providing in said shutter two further lateral opposite shutoff flattenings which are at right angle with respect to said known flattenings defining said inlet and outlet ports of the shuttle through hole.

Further conformations and developments of the shutters according to the invention are inferable from the dependent claims . With the shutters according to the invention it is possible to achieve important manufactural , structural and functional advantages.

Firstly, with equal shutter diameters, the sliding friction between the sealing rings and the shutter during the opening/closing movements of the valve is considerably reduced, and said sliding friction reduction is prominent indeed, as it may be observed for example with valves having shutter diameters between 1 and 4 inches (2,54 - 10, 16 cm) .

The through hole may be advantageously provided cylindrical, so that in the flowing liquid are avoided turbulence phenomena. The elimination or removal of both opposite shutter segments which, when the shutter is the closed position, in the known shutters were located inside the sealing rings, allows the provision of two opposite shutoff flattenings, on which can freely deposit the known calcareous incrustations and the like without causing any functional problems at all. In fact, during the opening rotation possible incrustations on said lateral dead shutoff flattenings will not be in contact with both sealing rings, so that the latter will not undergo any abrasion and will have a long durability.

At the same time will be wholly eliminated the known clampings which are due to the incrustations onto the shutters after the latter have been for a long period in their closed position.

These and further advantages which will be apparent from the following description are achievable with ball shutters consisting both of metal and plastics.

With the feature set forth in claim 2 it is possible to achieve a further remarkable lightening of the shutter according to the invention.

Claim 3 suggests a further possibility for lightening the shutter and efficiently counteracting possible damages due to the formation of incrustations.

Further possibilities for lightening the shutter according to the invention are also stated in claim 4.

A simplification of the dies for the manufacturing of the shutter according to the present invention can be achieved adopting the features according to claim 5.

The feature set forth in claim 6 enables to avoid the known drawbacks caused by a possible freezing of the liquid present between the valve body and the outer surface of the shutter in the closed position.

With the feature stated in claim 7 it is also possible to use the shutter according to the present invention for additional functions besides the opening/closing movement, for example for a drain function. Claim 8 suggests an extremely advantageous manufacturing of shutter preforms, which manufacturing requires only a moderate chip-forming machining which, in turn, can be advantageously accomplished with automatic machine tools.

The present invention also relates to said preforms for producing ball shutters according to the present invention, as well as to ball shutters made of plastics, and to ball valves comprising a shutter according to the present invention.

Brief Description of the Drawings

Further features, advantages and details of the ball shutters according to the present invention will be further apparent from the following description of some preferred embodiments of a ball shutter according to the present invention, shown in the accompanying drawings, in which:

Figure 1 is a perspective view of a shutter according to the present invention;

Figure 2 is a middle section view taken along line II-II of Figure 3 ;

Figure 3 is a top plan view of the shutter of Figure 1 ;

Figure 4 is a plan view of the shutter of Figure 1, looking from the bottom thereof;

Figure 5 is a side elevation view, looking according to the arrow A of Figure 3 , and 8

Figure 6 is a side elevation view, looking according to the arrow B of Figure 3.

Description of the preferred embodiments

The shutter 1 has a one-piece shutter body 2 which, in the shown example, is produced by hot-pressing as discussed hereinafter. In the shutter body 2 is provided a through hole 3 which at the external spherical surface of the shutter 1 defines the inlet and outlet ports 4A and 5A which, in turn, define two opposite flattenings 4, 5 of the shutter body 2, like the known shutters. Like the known ball shutters, the shutter 1 has further a seat 7 for housing the internal, not shown, end of an operating shaft or rod which is not shown and is associated with an operating member like a lever, handle, handwheel or the like. The configuration of the seat 7 can be chosen at will.

According to the present invention the shutter 1 is provided with two further lateral opposite dead flattenings 8, 9 which act ad shutoff flattenings and are provided at right angle with respect to the flattenings 4, 5 defined by the inlet and outlet ports 4A and 5A of the through hole 3.

In a further embodiment of the invention, in said shutoff flattenings 8, 9 is provides a recessed chamber 10 and 11, respectively, which contribute to the lightening of the shutter and allow to receive therein the occurring known sedimentations, calcareous incrustations or the like. In a further development of the present invention, the shutter body 2 has likewise an upper flattening 13 which defines, in the shown example, an annular crown 14 and/or a lower flattening 16 defining an annular crown 17. The short dashes line C shows the sphere enveloping the shutter 2.

From the drawings it may be seen that in the upper and lower flattenings 13 and 16 inside the annular crowns 14 and 17 is provided a profiled recess 18 and 19, respectively, which are substantially formed by two opposite depressions 21, 22 and 23, 24 which are parallel to the longitudinal axis of the through hole 3. Said recesses 18 and 19 contribute to further reduce the weight of the shutter 1.

In a further development of the invention, in the seat 7 housing the operating rod are provided one or two per se known through slots 25, 26.

According to a further embodiment of the invention, the shutter 1 has also a drain hole 27, Figure 5, which connects the through hole 3 with a lateral flattening 8 or 9, for example for drainage purposes, for example of expansion tanks in heating and warm water distribution plants . 10

The body 2 of the shutter 1 according to the present invention has essentially a cube-like configuration, whose sides are formed by the flattenings 4, 5, 8, 9, 13 and 16 and whose edges and corners are rounded and stand in the outer sphere of the shutter 1, that is they are parts of the imaginary sphere enveloping the shutter body 2. Such a shutter 1 may be manufactured in one piece of metal forming a preform which is produced as a metal casting or by hot-pressing. In the case of a production by hot- pressing the shuttle preform can be obtained starting from a small solid cylinder made of brass or the like, advantageously in one-phase hot-pressing, which allows to achieve lower manufacturing times and costs . In is stressed that the shutter preforms according to the present invention have a very high strength which allows an unobjectionable clamping of the shutter bodies in the automatic machine tools without any deformations of the shutter body, so that after the chip- forming machining for obtaining the external spherical shape of the shutter, the latter doesn't present any contraction phenomena, and therefore the external shutter spherical shape can be kept in an unobjectionable way.

For example during said chip-forming machinings the through hole is obtained in a very precise size and it is possible to form said operating seat 7, in case along with 11

said through slots 25, 26, as well as the lightening recessed chambers 10 and 11 in the opposite shutoff flattenings 8 and 9.

Notwithstanding the greater stiffness and sturdiness of the shutters according to the present invention with respect to the prior art shutters, it is stressed that the shutters according to the present invention, that is provided with said above discussed lightenings, have a lower weight in comparison with prior art shutters having equal external diameters .

In the case of shutters made of plastics, said shutters may be easily produced with the several above depicted configurations or embodiments by use of the known injection molding.

By providing molds having internal polished surfaces it is also possible to produce completely finished shutters which do not require a subsequent chip-forming machining. FUNCTION

With regard to the opening/closing rotational movements of the shutter the function is exactly like the function of the known ball shutters. With regard to the tightness and the durability it is observed the following. Due to the fact that with the high sturdiness of the metal shutters according to the present invention it is possible to surely avoid contractions of said shutters after they are 12

removed from the machine tool, the metal shutters according to the present invention keep the unobjectionable sphericity of their outer surface, and the tightness action between the sealing rings and the shutter is, therefore, assured in an unobjectionable manner and along with a smooth movement of the shutter, also after a very long rest of the valve in the closed position, and this practically apart from the shutter dimensions. This has been observed for example with valves having shutters with outer diameters ranging from 1 to 4 inches (2,54 - 10,16 cm) . Said smooth movement is also assured by the small spherical surfaces that engage the sealing rings and are smaller with respect to the correspondent great engaging surfaces of the prior art shutters . As to the achieved durability, the latter is practically the maximal one. In fact deposits of sedimentations or incrustations onto the shutter body are avoided, which deposits could cause abrasions or tearings of the sealing rings. According to the present invention said sedimentations or incrustations will take place on surfaces or chambers which are provided to this purpose and, therefore, said sedimentations or incrustations are hindered to contact the sealing rings during the opening/closing shutter rotations. 13

With respect to the prior art valves the present invention provides, therefore, a function having a smaller friction and a smaller stressing action onto the sealing rings, that is with a better tightness in comparison with the prior art shutters, and this with metal shutters having an unobjectionable outer sphericity and a low weight. The low weight of the metal shutters, in combination with the simplicity and quick manufacturing, for example by one- phase hot-pressing, and subsequent chip- forming machining on automatic machine tools, provide shutters which can be produced at a low cost. To achieve this result also contributes the fact that in consequence of the elimination of the shutter contraction phenomena due to the inherent elasticity after the chip- forming machining, during the manufacturing there are practically no discard shutter due to sphericity deformations of the shutters. From the above structural and functional description it is inferable that the shutter according to the present invention made of metal or plastics efficiently solve the stated objects and achieve the advantages set fort above. The lightening degree may be chosen at will. For example, the manner of producing the chambers 10 and 11 as well as the configuration of the other lightening recesses 18 and 19 can be carried out at will, that is for an amount which can be freely chosen, either singularly or in combination 14

with one another, and this in both cases of the metal or plastics shutter production.

Practically also the shape of the seat housing the operating rod may be chosen in one of the several actually known configurations.

As to the materials, in practice can be used all the materials actually used for manufacturing the different configurations of ball valves, for example metals, as brass or metal resisting to chemically corrosive liquids or plastics.

Besides the shutter, within the scope of the present invention reside also the shutter preforms and the valves comprising ball shutters according to the present invention, and this with any valve sizes and constructions .

Claims

15Claims

1. Shutter for ball valves comprising a shutter body (2) including a spherical outer surface, two opposite flattenings (4, 5) defining the inlet and outlet ports (4A, 5A) of the through hole (3) of said shutter (1), as well as a seat (7) for housing an operating rod, characterized in that it is provided with two further lateral opposite shutoff flattenings (8, 9) which are at right angle with respect to said flattenings (4, 5) defining said inlet and outlet ports (4A, 5A) of the through hole (3) .

2. Shutter for ball valves according to claim 1, characterised in that the body (2) of the shutter (1) has also an upper flattening (13) in which is provided said seat (7) for housing the operating rod and/or a lower flattening (16) so that the shutter body (2) has a substantially cube- like configuration having rounded edges and corners .

3. Shutter for ball valves according to claim 1, characterised in that in said shutoff flattenings (8, 9) is provided a recessed chamber (10, 11), respectively, for lightening purposes and for receiving thereon occurring incrustation deposits.

4. Shutter for ball valves according to claim 2, characterised in that in the upper flattening (13) and/or 16

lower flattening (16) are provided lightening recesses (18, 19) .

5. Shutter for ball valves according to one or more of the preceding claims, characterised in that the through hole

(3) has a constant diameter.

6. Ball shutter according to one or more of the preceding claims, characterised in that in said seat (7) for housing said operating rod is provided at least a trough slot (25; 26) opening into the trough hole (3) .

7. Shutter for ball valves according to one or more of the preceding claims, characterised in that in at least a lateral shutoff flattening (8, 9) is provided a drain hole

(27) which opens into the through hole (3) of the shutter

(1) .

8. Shutter for ball valves according to one or more of the preceding claims, characterised in that it has a configuration allowing the manufacturing of the shutter preform by one-step hot-pressing in a cube-like configuration starting for example from a solid small cylinder, which preform is subsequently machined by chip- forming machining for providing the necessary sphericity and for obtaining a weight lightening of the shutter body

(2) .

9. Preform having essentially a cube-like configuration according to claim 8, provided for the manufacturing of 17

ball shutters according to one or more of the claims 1 through 8.

10. Shutter for ball valves according to one or more of the claims 1 through 9, characterised in that it is produced in metal by casting or in plastics by injection moulding or the like.

11. Ball valve comprising a valve body with an operating member and opposite sealing rings for housing a ball shutter in a shutter chamber, characterised in that it houses a ball shutter (1) according to one or more of the preceding claims 1 through 8, 10 and 10.