GB1563350A - Switching valve - Google Patents

Description

(54) SWiTCHiNG VALVE (71) We, IHARA CHEMICAL INDUSTRY Co., LTD., a Japanese Company, 2-26, 1chome, Ikenohata, Taito-ku, Tokyo, Japan, 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 statement:- This invention relates to a switching valve for an apparatus for manufacturing polyurethane elastomers or the like.

To assist in understanding the present invention, the two component-one shot method, one of the well known methods for manufacturing polyurethane elastomers, will now be briefly described. This two component-one shot method consists of the steps of (a) preparing a mixture of a polyester (or a polyether) and an activator, and (b) supplying a predetermined volume of said mixture and a predetermined volume of an isocyanate from their respective containers to a mixer chamber with the aid of respective metering pumps, while carrying out continuous measurement of the supplied liquids.

and continuously discharging the final mixture through a nozzle in the mixer chamber into a moulding die. Due to the size and quantity of the required moulded products, however, the moulding operations often take place with the use of a switching valve which is operated intermittently. Once charging into the mould has been completed, the mixture starts to solidify in the mixer chamber.

To avoid the solidification in the mixer chamber, the interior of the mixer chamber is flushed with solvent every time a charging operation is completed, and then any residual material on the wall of the chamber is blown away with air. Such a flushing operation, using solvent and air, causes undesirable contamination in the working environment, a considerable loss of starting material at the start of the mixing operation, and fluctuation in the ratio of starting materials one to another.

According to the present invention, there is provided a switching valve for an apparatus for manufacturing polyurethane elastomers or the like, comprising (a) a cylindrical valve body having five openings equiangularly disposed around said body, and (b) a closure member rotatably mounted within the valve body and having two separate grooves formed therein, one groove allowing communication between two adjacent openings and the other groove allowing communication between two other adjacent openings while the remaining fifth opening is closed by the closure member.

For a better unterstanding of the invention, reference will now be made, by way of example, to the accompanying drawings in which: Figure 1 is a sectional view of a switching valve of the invention; Figure 2 is a cross-sectional view of the switching valve shown in Figure 1; and Figure 3 its a schematic view of a moulding apparatus in which switching valves according to the invention can be used.

Referring to Figures 1 and 2, a cylindrical valve body 1 forming the outer housing of a switching valve V is provided with five openings (1), (2), (3), (4) and (5) at equal angular distances around the periphery thereof.

In the interior of the valve body 1 there is a switching mcmber 2 forming a closure member, the two ends 2a and 2b, of reduced diameter, of the switching member 2 being rotatably supported by means of ball bearings 4 and 4a in a main frame 5 which is retained by sealcovers 3 and 3a. The inner surface of the valve body 1 slidably contacts the outer surface of the enlarged portion 2c of the closure member 2. The numerals 6 and 6a denote oil seals. On the closure member 2 there are provided grooves 7 and 8 the width of each of which is al most equal to the diameter of the openings (1) to (5) (compare the opening (4) with the groove 8 in Figure 1). The length of the grooves 7 and 8 is such that two adjacent openings of the five openings (1) to (5) are in communication through the groove 7 or 8.For instance, the openings (1) and (5) communicate through the groove 8 and the openings (2) and (3) communicate through the groove 7 in the case shown in Figure 2.

The residual periphery portion 2d of the closure member 2 serves to close the other opening (4). Therefore the opening (4) is not in communication with the other openings.

A typical embodiment of the switching valve according to the present invention has been described, and an application of this valve to the manufacture of elastomers of polyurethane will now be described with reference to Figure 3, in which three valves V1, V2, V3, each as shown in Figures 1 and 2, are utilized.

The numeral 41 denotes a reservoir tank for a mixture (hereinafter referred to as liquid A) of polytetramethylene ether glycol and 4,4'-diamino-2,3,2',3'-tetrachlorodiphenylmethane, and the numeral 42 denotes a reservoir tank for a mixture (hereinafter referred to as liquid B) of 80% of 2,4-toluenediisocyanate and 20% of 2,6-toluenediisocyanate. The reservoir tanks 41 and 42 are connected to inlets (1) and (1) of switching vales V1 and V2 via metering pumps 43 and 44, respectively Obviously means for connection comprises connection pipes.

Outlets (2) and (2) of switching valves Vl and V2 are connected to mixer chamber 45, and the outlet of the mixer chamber is connected to the inlet (1) of the switching valve V3. Outlet (2) (nozzle) of the switching valve V3 is connected to a mixture receptacle, for instance, a moulding die 46.

Solvent or detergent (for instance, polypropylene glycol) is stored in another reservoir tank 47, which is connected to inlet (4) of the switching valve V3 via metering pump 48. Outlet (3) of the switching valve V3 is connected to inlets (3) and (3) of switching valves V1 and V2. Further outlets (4), (4) and (5) of the switching valves V, V2 and V3 are connected to the reservoir tank 47 for detergent, while outlets (5) and (5) of the switching valves V1 and V2 are connected to the respective reservoir tanks 41 and 42.

At a steady state in the first stage, that is, before mixing the liquids A and B, the openings (1) and (5) as well as the openings (2) and (3) of the switching valves V1 and V2 are in communication, while the openings (1) and (5) as well as the openings (3) and (4) of the switching valve V3 are also in communication. Due to this arrangement, there is formed for the liquid A and B, respectively, recycle lines from the metering pump 43 or 44 through the openings (1) and (5) in the switching valve V1 or V2 to the reservoir tank 41 or 42.For the detergent S another recycle line is formed, from the metering pump 48 through the openings (4) and (3) in the switching valve V3, through the openings (3) and (2) in both switching valves V1 and V2, through the mixer chamber 45 and then through the openings (1) and (5) in the switching valve V3 to the reservoir tank 47.

Next, in the second stage, the switching valves V1 and V2 are switched over to make communication between the openings (1) and (2) as well as between the openings (3) and (4). This causes the liquids A and B to pass through the openings (1) and (2) in the switching valves V1 and V2 to be mixed in the mixer chamber 45 (initially resulting however in a detergent-containing mixture due to the fact that the mixer chamber is initially filled with the detergent S) and then to flow into the reservoir tank 47 through the openings (1) and (5). On the other hand the detergent S passes through the openings (4) and (3) in the switching valve V3 and then through the openings (3) and (4) in the switching valves V1 and V2 to flow back into the reservoir tank 47.

Moulding is commenced as soon as a mixture not containing detergent is obtained.

Thus, the switching valve V3 is switched so that the openings (1) and (2) as well as the openings (4) and (5) are in communication. As a result the mixture in the mixer chamber 45 passes through the openings (1) and (2) in the switching valve V3 into the moulding die 46 to be moulded therein. At the same time, the detergent S flows back to the reservoir tank 47 through the openings (4) and (5) in the switching valve V3.

Finally, in the third stage, the switching valve V3 is switched back to again make communication between the openings (1) and (5) as well as between the openings (3) and (4), as the mixing of the liquid A and B comes to its completion. This allows the mixture of the liquids A and B to flow out through the openings (1) and (5) in the switching valve V3 to the reservoir tank 47 for the detergent, while the detergent S passes through the openings (4) and (3) in the switch valve V3 and then through the openings (3) and (4) in the switching valves V1 and V2 and flow backs to the reservoir 47. Then as the switching valves V1 and V2 are switched over to again make com- munication between the openings (1) and (5) as well as between the openings (2) and (3), recycle lines are again formed for the liquids, A and B, respectively, in which the liquids A and B pass through the openings (1) and (5) in the switching valves V1 and V2 and flow back to the respective reservoir tanks 41 and 42. The detergent S passes through the openings (4) and (3) in the switching valve V3 and through the openings (3) and (2) in the switching valves V1 and V2, flows into the mixer chamber 45 to clean it and further passes through the openings (1) and (5) in the switching valve V3 to flow back to the reservoir tank 47.Of course the switching valves Vl and V2 may be switched over at the same time as the switching valve V3 is switched over.

As the third stage is over, the steady state in the first stage is attained. The above steps of operation is repeated by refilling the tanks 41 and 42. As is obvious from the above description, the switching valves Vl, V2 and V3 are each provided with two inlets and three outlets, one of the three outlets (openings (2) in valves Vl and V2 and opening (5) in valve V3) being a common outlet for the two inlets.

WHAT WE CLAIM IS: - 1. A switching valve for an apparatus for manufacturing polyurethane elastomers or the like, comprising (a) a cylindrical valve body having five openings equi-angularly disposed around said body, and (b) a closure member rotatably mounted within the valve body and having two separate grooves formed therein, one groove allowing communication between two adjacent openings and the other groove allowing communication between two other adjacent openings while the remaining fifth opening is closed by the closure member.

2. A switching valve substantially as hereinbefore described with reference to, and as shown in, Figures land 2 of the accompanying drawings.

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

Claims (2)

**WARNING** start of CLMS field may overlap end of DESC **. reservoir tanks 41 and 42. The detergent S passes through the openings (4) and (3) in the switching valve V3 and through the openings (3) and (2) in the switching valves V1 and V2, flows into the mixer chamber 45 to clean it and further passes through the openings (1) and (5) in the switching valve V3 to flow back to the reservoir tank 47. Of course the switching valves Vl and V2 may be switched over at the same time as the switching valve V3 is switched over. As the third stage is over, the steady state in the first stage is attained. The above steps of operation is repeated by refilling the tanks 41 and 42. As is obvious from the above description, the switching valves Vl, V2 and V3 are each provided with two inlets and three outlets, one of the three outlets (openings (2) in valves Vl and V2 and opening (5) in valve V3) being a common outlet for the two inlets. WHAT WE CLAIM IS: -

1. A switching valve for an apparatus for manufacturing polyurethane elastomers or the like, comprising (a) a cylindrical valve body having five openings equi-angularly disposed around said body, and (b) a closure member rotatably mounted within the valve body and having two separate grooves formed therein, one groove allowing communication between two adjacent openings and the other groove allowing communication between two other adjacent openings while the remaining fifth opening is closed by the closure member.

2. A switching valve substantially as hereinbefore described with reference to, and as shown in, Figures land 2 of the accompanying drawings.