GB2125942A - Switch valve - Google Patents

Abstract

An inflow duct 11 is connected with two outflow ducts 12, 12' and two valve-holding bores 14, 14' in which two valve bodies 13, 13' are slidably and rotatably inserted. When either one of the bodies (13) closes the entrance (31) of a corresponding outflow duct (12), an inner end portion of the body (13) extends through the entrance (31) and into the inflow duct 11, the end surface 13a of the end portion being concave and constituting part of a passage connecting the inflow duct 11 to the other outflow duct (12'). In this way stagnant regions can be avoided between the inflow duct and the outflow ducts. The relative positions of the ducts 12, 12' and bores 14, 14' may be reversed. <IMAGE>

Description

SPECIFICATION Switch valve The present invention relates to a switch valve, particularly (but not solely) for use in pipelines for supplying polymers and other viscous liquids having high viscosity and high temperature.

In the production of plastics products, synthetic fibres, etc., it has been usual to adopt the number of operation according to which a pair of similar apparatuses are operated in turn and the starting materials are supplied to each operating apparatus with the use of a switch valve. In this case, however, a part of the starting material is accumulated in the inside of the switch valve, the accumulated material is carbonized with an elevated temperature, and the resulting carbonized material is as such sent into the apparatus. Accordingly the product obtained is not uniform in its quality, and particularly in case of producing synthetic fibres, the incorporation of such carbonized fine powders thereinto can not afford the production of fibres having good quality because the resulting fibres are to be cut off at the portion where the carbonized powders are incorporated.

Under these circumstances, the present inventor has made various investigations on how the above-mentioned problems occurred and has made various proposals for removing the causes thereof.

Thus, how the carbonization as mentioned above occurs is explained, in reference with the prior art, as follows.

Figure 1 shows a conventional switch valve 1 which is installed in a plant for producing plastics products, synthetic fibres, etc. In the switch valve 1, are provided a single inflow pipe 2 for introducing the starting material having high viscosity and two outflow pipes 3, 3' for sending out the starting material. Inside the switch valve, the inflow pipe 2 and the outflow pipes 3, 3' intersect at one point to branch away into three directions. Close to the turning point where the inflow pipe and the outflow pipes branch away, valve-holding pipes 4, 4' are provided and are united with the inflow pipe and the outflow pipes.

Inside the valve-holding pipes 4, 4', respective bodies 6, 6' are inserted and slide freely so as to open and close the outflow pipes 3, 3'. The valve bodies 6, 6' each have vertical surfaces at their inner end surfaces. Outside the valve housing 5 which contains the inflow pipe, the outflow pipes, and the valve-holding pipes, there is a jacket 8 which covers the valve housing at a regular spacing and is completely shut off from open air.

In the jacket 8 an oil as a heat medium for maintaining high temperatures passes through.

The oil is usually at 300 to 3200 C.

In the practical use of such conventional switch valve, the valve body 6' approaches the inflow pipe 2 so as to close the outflow pipe 3', while the valve body 6 goes away from the inflow pipe 2, whereby a passage from the inflow pipe 2 to the outflow pipe 3 is formed. In this state, when the starting material is sent out from the inflow pipes ~ to the outflow pipe 3, it completely fills the whole space in the passage. When the starting material flows in the passage practically, however, it flows mainly in the space where the flowing resistance is the least, that is, the portion shown by the chain line in Figure 1. As a result, at approximately triangular corners 7, 7' which are formed by the end surfaces of the valve bodies 6, 6' and the valve-holding pipes 4, 4', flowing of the starting material is hardly seen.Starting material which has stagnated in the corners 7, 7' for a long period of time is hardened by carbonization.

The resulting carbonized starting material blocks the valve body 6, and then, by switching action for opening the valve body 6', the carbonized material is forced out in the state of particles or masses in the middle of the passage from the inflow pipe 2 to the outflow pipe 3. Thus, starting material containing such carbonized substances is as such sent into the apparatus for producing plastics products, synthetic fibres, etc.

The apparatus as used above is usually provided with filters or nozzles having various sizes depending on the products. Particularly in case of production of synthetic fibres, the filter or nozzle becomes clogged with the carbonized substances.

Fine powders of the carbonized substances passing through the filter are mixed into the product, which gives fatal disadvantages to its quality.

Thus, the conventional switch valve has the following disadvantages; a part of the starting material is stagnated without flowing on, followed by carbonization, and the carbonized substances are mixed into the product, which results in lowering of extension properties in case of fibres, and deteriorating the quality of the product obtained.

The present invention provides an improved switch valve in which the valve body going forward and backward (e.g. by turning a handle) has an inner end surface having an inclined surface, whereby there can be removed the unnecessary portion in which the starting material is stagnated in the middle of the passage.

Accordingly, the invention provides a switch valve which comprises a valve housing consisting of a inflow pipe connected with two outflow pipes and two valve-holding pipes, and a valve body being inserted in the valve-holding pipe in said valve housing to slide and rotate therein, in which the inner end portion of the valve body is extended from the opening of said outflow pipe, under the condition that the opening of the outflow pipe is closed with said valve body, and the surface of said inner end portion of the valve body has a shape of hollow, curved surface, said hollow, curved surface constituting a part of a passage connecting said inflow pipe with said outflow pipes.

The invention will be described further, by way of example, with reference to Figures 2 to 7 of the accompanying drawings, in which: Figure 1 is a fragmentary vertical sectional view of a conventional switch valve; Figure 2 is a fragmentary vertical sectional view of a switch valve according to the present invention; Figure 3 is a plan view showing the whole of the switch valve of Figure 2; Figure 4 is a section on line XX in Figure 3; Figure 5 is a fragmentary vertical sectional view of part of the switch valve, in another embodiment, wherein the shape of the end surface of each valve body is changed; Figure 6 is a fragmentary sectional view of part of the switch valve, in another embodiment, wherein the position of the valve body and the outflow ducts are changed; and Figure 7 is a fragmentary sectional view of part of the switch valve in Figure 6, in another embodiment, wherein the shape of each valveholding bore is slightly changed.

The following description is of a switch valve 9 by which the flow of a starting material can be changed into either of two directions.

In a valve housing 10 (Figure 2) there are two valve-holding bores 14, 14' which are cylindrical and are connected, meeting at right angles, with an inflow duct 11. Inside the bores 14, 14' are inserted respective valve bodies 13, 13' which are able to slide forward and backward therein.

Through a part of the bores 14, 14', two outflow ducts 12, 12' are connected with the inflow duct 1 The valve bodies 13, 13' each have an inner end surface which is one of the characteristic features of the present invention. In connection with this matter, more detailed explanation will be made below.

When the valve body 1 3 advances toward the inflow duct 11, the valve body 13 bears against a valve seat 31 to close the outflow duct 12. In this case, a spherically concave, inclined surface 1 3a of the valve body 13 faces obliquely upwards. On the other hand, the valve body 13' is moved back away from the inflow duct 11, and the corresponding spherically concave, inclined surface 1 3a' of the valve body 1 3' faces obliquely downwards. Thus, a passage between the inflow duct 11 and the outflow duct 12' is defined between the inclined surfaces 1 3a, 1 3a'.

The connection is changed in the following manner. The valve body 13 is moved back away from the inflow duct 11 and is positioned with its inclined surface 1 3a facing obliquely downwards; the valve body 13' is advanced to a valve seat 31' and is positioned with its inclined surface 1 3a' facing obliquely upwards. As a result, a passage is defined from the inflow duct 11 to the outflow duct 12, while the passage from the inflow duct 11 to the outflow duct 12' is b!ocked.

As to the operation mechanisms Z, Z' of the valve body 13, 13', the valve bodies 13, 13' are inserted in the valve-holding bores 14, 14' so as to be capable of moving forward and backward.

The valve bodies 13, 13' are combined with respective valve rods 21,21' which are provided with screw-threading on the outer circumference.

Hand-wheels 18, 18' are screwed onto the valve rods 21,21', respectively. These hand-wheels are held in a state of free rotation by bearing elements 1 6, 1 6' which are fixed by pairs of holding rods 1 5, 1 5' (Figure 3) on flanges 33, 33' which are provided in rigid connection with the valve housing 10.

The hand-wheels 1 8, 1 8' are held by inserting them into the outer end of a respective sleeve 1 7 which is held in free rotation by the bearing elements 1 6, 1 6'. The bearing elements 16, 16' are installed on the holding rods 1 5, 1 5' by flanges 1 6a', 1 6a' projecting on the both side portions of the bearing elements. The sleeves 1 7 each have an internal screw-threaded portion 20 into which is screwed a screw portion 1 9, 1 9' of the respective valve rod 21.21'. Between the holding rods 1 5, 1 5' are bridged lateral bars 22, 22' (Figure 4) at the approximately central portion of each holding rod.In each of the respective circumferential walls of the outer end portions of the valve bodies 13, 1 3' are symmetrically engraved two screw grooves 23, each extending over a semi-circumference of the said wall. Rollers 24 set in the screw grooves 23 are installed on the lateral bars 22. The length (S) of the screw grooves 23 in the horizontal direction is equal to the distance which is required for the valve body 13 to move so as to change the passage. Thus, in accordance with the movement of the valve body 13 going forward and backward, the valve body 1 3 is half-rotated.

The space between the valve-holding bore 14, to the outer end thereof, and the valve body 1 3 is filled with packing 25 for preventing the starting material from leaking out. The packing 25 is pressed with packing glands 26, 26' set on the outer circumference of the valve body 13, 13'. The packing 25 is compressed by bolting flanges 27, 27' on the end surface of the packing glands 26, 26' with bolts 28, 28'.

On the outside of the valve housing 10 there is a uniformly spaced jacket 29 for maintaining an elevated temperature. At the end portions of the inflow duct 11 and the outflow ducts 12, 12' there are flanges 30 for connecting the said ducts to the corresponding apparatus, respectively.

Inlets 32 for a heat medium are provided in the flanges 30 and open into the jacket 29.

In the above construction, the rollers 24, 24' are each provided on the upper and lower sides (as shown in Figure 2). Alternatively, only one of the said rollers may be provided at each end, and in this case the screw groove may also be single.

Figures 5 to 7 show other embodiments of the present invention, which comprise modification of the inclination and shape of the end surface of the valve body so that the two outflow ducts 12, 12' can simultaneously be closed, which is impossible in the embodiment of Figure 2.

Figure 5 shows an embodiment wherein, the movement of the valve bodies 13, 13' being rectilineal as in the embodiment of Figure 2, the shape of the end surface 1 3a of the valve bodies is different from that of Figure 2, i.e. the end surface is partly inclined and partly at a right angle with respect to the moving direction of the valve bodies. When the valve bodies having such shape meet, a part of the end surface (of a shape of right angle) of each valve body comes in contact with the other on a straight line. On the other hand, when the valve bodies 13, 13' go backwards, the valve bodies are semi-rotated and thereby the inclined portion of the end surface of each valve body is reversed, as in the embodiment of Figure 2; this is because the mechanism of moving the valve bodies 13, 13' in Figure 5 is the same as in Figures 2 to 4.The end surface is cylindrically concave.

Figure 6 shows an embodiment in which the position of the outflow ducts 12, 12' is modified, i.e. the outflow ducts are positioned in a straight line, while the shape of the end surface of each valve body is the same as that of Figure 2, i.e. a spherically concave, inclined surface.

Figure 7 shows an embodiment wherein the position of the valve bodies is the same as in Figure 6, and simultaneous advancement of the valve bodies 1 3, 1 3' can make it possible to close both outflow ducts 12, 1 2'.

In the embodiment of Figures 5 to 7, the moving direction of the valve bodies and the shape of the end surface thereof are selected so that the two valve bodies may not be hindered each other on their meeting.

The following explanation of the operation of the switch valve is made with reference to Figures 2 to 4. The starting material having high viscosity which is supplied through the inflow duct 11 is introduced into the outflow duct 12', taking the shortest way, owing to the part-spherical, inclined surfaces 1 3a, 1 3a' of the valve bodies 13, 13'.

Since there are no significant hollows in which the starting material can stagnate in the passage from the inflow duct 11 to the outflow duct 12', the starting material can smoothly move therein.

The switch valve described above can be used in connection with two apparatuses for producing plastics products, synthetic fibres, etc., while supplying the starting material into either one of them in turn. When one apparatus is stopped for inspection or for cleaning filters, the other apparatus is operable as the starting material is continuously supplied. Referring to Figure 2, the apparatus connected with the outflow duct 12' is in operation, while the apparatus connected with the outflow duct 12 is under the condition wherein inspection of the apparatus and cleaning of filters can be effected. In turn, when the apparatus connected with the outflow duct 12' is to be inspected, first the passage from the inflow pipe 11 to the outflow pipe 12' is to be closed.

The hand-wheel 18' is turned so as to advance the valve body 13' towards the central portion, whereby the valve body 13' is pushed forward while rotating by the interaction between the rollers 24 and the screw grooves 23. When the valve body 13' reaches the final position, it has been semi-rotated to turn the spherically concave, inclined surface 13a' of the valve body 13' up. At the same time, the hand-wheel 1 8 is turned to withdraw the valve body 1 3. When the valve body 1 3 reaches the final position shown by chain line in Figure 2, it has been semi-rotated by the interaction between the rollers 24 and grooves 23 to turn the inclined surface 1 3a of the valve body downwards. Thus, the inflow duct 11 is connected with the outflow duct 12.

The provision of arcuately concave, inclined surfaces 13a, 13a' on the end surface of each valve body can make it possible to avoid hollows in which the starting material is accumulated in the passage, and therefore the starting material is never carbonized, even with the introduction of a heat medium of high temperatures (300 to 3200 C) in the jacket 29. Accordingly, even when the outflow duct is changed by operating the valve bodies, carbonized fine particles or masses are never mixed into the product. Thus it is possible to supply the desired product having uniform quality, and further, the clogging of filters provided on the apparatus can be removed. Particularly in case of production of synthetic fibres, since carbonized fine powders are never mixed into the fibres, a product having high quality can be obtained without cutting of the fibres.

The embodiments of Figures 5, 6, and 7 have, in addition to the advantageous effects as above, the characteristic that two outflow pipes can simultaneously be closed, this affording wider utilization. Among them, the embodiment of Figure 7 can afford the most effective means for preventing the starting material from carbonization, in consideration of lessening any accumulation of the starting material in comparison with that of Figures 2, 5, or 6.

Claims (6)

1. A switch valve comprising a valve housing having an inflow duct connected with two outflow ducts and two valve-holding bores, and two valve bodies slidably and rotatably inserted in the respective valve-holding bores, in which, when either one of the valve bodies is in a closing position in which it closes the entrance of a corresponding one of the outflow ducts, an inner end portion of the valve body extends through the entrance of the outflow duct and into the inflow duct, the end surface of the end portion being concave and constituting part of a passage connecting the inflow duct to the other outflow duct.

2. A switch valve as claimed in claim 1, in which means are provided for rotating each valve body as it moves towards and away from the closing position.

3. A switch valve as claimed in claim 2, in which the said means comprise a screw groove cooperating with an element projecting into the groove.

4. A switch valve as claimed in any preceding claim, in which the valve-holding bores are aligned at right-angles to the inflow duct, and the end surface of each valve body has a first part defined by a plane perpendicular to the sliding direction of the body and a second part defined by a plane inclined in relation to the first-mentioned plane.

5. A switch valve as claimed in any of claims 1 to 3, in which the outflow ducts are aligned at right angles to the inflow duct, the valve-holding bores are oblique to the ducts, and the valve bodies are arranged so that the outflow ducts can be simuitaneously closed.

6. A switch valve substantially as described with reference to Figures 1 to 4, Figure 5, Figure 6, or Figure 7 of the accompanying drawings.