The invention provides a balancing valve.

Balancing valves are designed for adjustment and closing of the flow in central heating networks, in hot and cold utility water installations, in air conditioning and cooling installations.

An adjustment poppet valve is known that is formed of a body closed with a cover, and where a suitably shaped head on a stem cooperates with a seat of the valve.

The stem has a knob at one end and is guided in a threaded part in the cover where it is also sealed. The valve is provided with a scale that shows the positioning of the head relative to the seat. Usually, the scale shows the number of turns of the stem, from the state completely closed, and fraction(s) of one full turn.

An important issue in the construction of an adjustment valve is to obtain repeatability of a preset valve loading, so as to make the construction capable to close the valve when needed, where re-opening is possible solely to a preset value.

Known balancing valves are provided with a head made of metal. Also such elements of the valve as a body with inlet and outlet connector pipes, and a cover are made of metal. Most frequently, cast iron or non-ferrous metal alloys are used for this purpose. Components of the balancing valve made of these materials require precise mechanical shaping. Such heads are at the same time expensive in manufacturing due to both material costs, in particular non-ferrous metals costs, and treatment costs related first to casting a product and then to mechanical shaping thereof.

From the specification of the Polish patent application PL 215630 B l a balancing valve is known, with a body that has two connector pipes. In the body a seat is housed, said seat being closed with a head mounted on a stem where the stem is seated in a gland. Outside the gland there is a knob connected to the stem. The valve is characterized in that the head is made of plastic and is connected to an adjustment ring which is made of plastics. The other elements of the valve, among others the body and a cover, are made of metal.

From the Polish utility model specification PL 66251 Y a head assembly of a balancing valve is known said valve being provided with a body which has an inlet connector pipe and an outlet connector pipe wherein in the body a closing seat is housed and the head is mounted on a stem where the stem is seated in a gland outside of which there is a knob connected to the stem. The head is made of plastics and the remaining elements of the valve, among others the body and a cover, are made of metal.

The valves which are made of metal are very susceptible to precision of manufacture and in the case of even minor dimensioning defects they may cause leakages at the contact area with the seat, and this is why in valves of this kind, equipped with metallic heads, it is necessary to use additional solutions to enhance sealing between the seat and the valve, involving for example resilient head suspension.

The balancing valve according to the invention is provided with a body that has two connector pipes, i.e. an inlet connector pipe and an outlet connector pipe, said valve being closed with a cover. In the body a seat is housed and closed with a head mounted on a stem. The stem is seated in a gland arranged in the cover, outside of which there is a knob connected to a stem with a bolt, and the valve is provided with sealing elements wherein the head is connected to an adjusting ring. The body and the cover are made of plastics, preferably of polysulfone or poli(phenylene sulfone) or poly(vinylidene fluoride) or polyetherimide.

Preferably, the head and the adjusting ring connected thereto are made of plastics, preferably of polysulfone or poly(phenylene sulfone) or poly(vinylidene fluoride) or polyetherimide or poly(phenylene sulphide).

Preferably, the head and the adjusting ring are connected by means of a threaded connection, and between the head and the adjusting ring a sealing of the head is arranged, preferably made of ethylene-propylene-diene rubber or butadiene-acrylonitrile rubber or fluorocarbon rubber or polytetrafluoroethylene.

Preferably, the thread of the threaded connection is formed both on the head and on the adjusting ring.

Preferably, the threaded connection between the head and the adjusting ring is secured with a self-tapping screw.

Preferably, the body, the cover head and the adjusting ring are made by injection method.

Preferably, the stem and an aperture stop are made of plastics, preferably of polysufone or poly(phenylene sulfone) or poly(vinylidene fluoride) or polyetherimide or poly(phenylene sulphide).

Preferably the knob has a scale of full turns and tenth of turns and is made of plastics, preferably poly amide or acrylonitrile-butadiene-styrene copolymer.

Preferably, the knob is screwed to the stem with a bolt made of plastics, preferably of polysulfone or poly(phenylene sulfone) or poly(phenylene sulphide) or poly(vinylidene fluoride) or polyetherimide. Preferably, the body is provided with a Venturi tube.

Preferably, the Venturi tube is made of plastics, preferably of polysulfone or poly(phenylene sulfone) or poly(phenylene sulphide) or poly(vinylidene fluoride) or polyetherimide.

Preferably, the body is provided with measuring connector pipes and measuring valves arranged at the inlet side and an additional connector pipe arranged at the outlet side.

Preferably, the valves are made of plastics, preferably of polysulfone or poly(phenylene sulfone) or poly(phenylene sulphide) or poly(vinylidene fluoride) or polyetherimide.

Preferably, the axis of the additional connector pipe and the axes of the measuring connector pipes are arranged on the same surface.

Preferably, sealing elements constitute sealing rings of an O-ring type.

Preferably, sealing elements are made of ethylene-propylene-diene rubber or butadiene-acrylonitrile rubber or fluorocarbon rubber.

Preferably, the stem, the aperture stop, the knob and the bolt are made by injection method.

The object of the invention is shown in its embodiments in the drawing, where Fig. 1 presents a valve in an axial section.

As shown in Fig. 1 a balancing valve 1 has a body 2 that has two connector pipes, namely an inlet connector pipe 3 and an outlet connector pipe 4. The body is closed with a cover 12 connected to the body 2 of the valve 1 by means of a threaded connection. In the body 2 a seat 5 is housed which is closed with a head 6 mounted on a stem 7. An adjusting ring 13 is mounted to the head 6 via a seal 14. The body 2 of the valve 1 is made of structural plastics which in this embodiment is polysulfone being a polymer containing an -SO2- group and an aromatic ring in the main chain. Both the body 2 and the cover 12 are made by injection method and solely some of the surfaces are subject to mechanical shaping, for example the ones where the seals are arranged or where a thread is necessary to provide a threaded connection. Unexpectedly, it turns out that plastics, including polysulfone, exhibit good technical properties for making both the body 2 and the cover 12, because if these elements are made by injection method they easily undergo mechanical shaping and maintain dimensional parameters ensuring tightness and durability of the valve. Especially significant in this case is forming in the body 2 of a seat 5 with which a head 6 cooperates and an adjusting ring 13 connected to it through a seal 14.

Obviously, both the body 2 and the cover 12 can be made of some other plastics that meet requirements with regard to strength, stability of dimensional parameters and durability.

In other embodiments, for making both the body 2 and the cover 12 poly(phenylene sulfone), poly(vinylidene fluoride) and polyetherimide have been used. These materials exhibit appropriate mechanical properties.

Inside the stem 7 an aperture stop 8 is arranged which stops opening movement of the head 6. The stem is seated in a gland 9 and terminates at the opposite side of the head 6 in a knob 10 used to open and close the valve 1. The head 6 together with the stem 7 and the gland are seated in a cover 12 that closes the hole above the seat 5 in the body 2 of the valve 1.

The head 6 and the adjusting ring 13 are made of structural plastics.

In this embodiment, the plastics for the head 6 and the adjusting rings 13 is polysulfone which is a polymer containing an -SO2- group and an aromatic ring in the main chain. Both the head 6 and the adjusting ring 13 are made by injection method and basically the surfaces where a seal is seated are subject to mechanical shaping, for example a seal where the head 6 cooperates with the seat 5 or where a thread is necessary for providing a threaded connection.

Similarly as in the case of the body 2 and the cover 12, the head 6 and the adjusting ring 13 can be made in other embodiments of some other plastics such as: poly(phenylene sulfone), poly(vinylidene fluoride), polyetherimide and poly(phenylene sulphide). These materials exhibit appropriate mechanical properties.

The head 6 is connected to the adjusting ring 13 at the side of the seat 5 of the valve 1. The connection of the head 6 with the adjusting ring 13 is a threaded connection wherein an external thread is formed on the head 6, and an internal thread is formed in the adjusting ring 13. Between the head 6 and the adjusting ring 13 a seal 14 for the head 6 is arranged with a flat cross-section and seated on one side on the surface of the adjusting ring 13, and on the other side on the front surface of the head 6. During making the connection of the head 6 to the adjusting ring 13, position of the seal 14 of the head 6 becomes fixed on the threaded connection. Upon connecting the head 6 to the adjusting ring 13 the threaded connection is locked by screwing a self-tapping screw (not shown) in.

The seal 13 of the head 6 in this embodiment is made of ethylene- propylene-diene rubber, however in other embodiments such materials as butadiene-acrylonitrile rubber, fluorocarbon rubber or polytetrafluoroethylene can be used.

The stem 7 and the aperture stop 8 arranged therein are also made of plastics. In this embodiment the material for both the stem 7 and the aperture stop 8 is polysulfone. However, also in this case other materials with similar properties can be used, such as poly(phenylene sulfone), poly(vinylidene fluoride), polyetherimide or polyphenylene sulfides. The knob 10 has a scale of full turns and tenths of turns and is made of plastics, and in this embodiment the material is polyamide, however in other embodiments other materials, such as acrylonitrile-butadiene-styrene copolymer, can be used.

The bolt 1 1 with which the knob 10 is screwed to the stem 7 is made of plastics, which in this embodiment is polysulfone. Other plastics materials for the bolt 1 1 can be poly(phenylene sulfone), poly(phenylene sulfide), poly(vinylidene fluoride) or polyetherimide.

The body 2 of the valve 1 on the side of the connector pipe 3 is provided with a Venturi tube 15 intended for measuring pressure at selected points of the valve 1 and determining instantaneous flow of the agent inside the valve 1.

The Venturi tube 15 is made of plastics which in this embodiment is polysulfone. In other embodiments, the Venturi tube 15 can be made of poly(phenylene sulfone), poly(phenylene sulphide), poly(vinylidene fluoride) or polyetherimide.

The body 2 of the valve 1 on the side of the inlet connector pipe 3 is also provided with measuring connector pipes 16 in which measuring valves 17 are seated cooperating with the Venturi tube 15. The body 2 of the valve 1 on the side of the outlet connector pipe 4 is provided with an additional connector pipe 18.

The measuring valves 17 are made of plastics. In this embodiment the measuring valves 17 are made of polysulfone, however in other embodiments they can be made of poly(phenylene sulfone), poly(phenylene sulphide), poly(vinylidene fluoride) or polyetherimide.

The valve 1 , where needed specifically, and in particular at connections or contact areas of individual elements, is equipped with sealing elements 19 which in this embodiment constitute sealing rings of an O-ring type. The sealing elements 19 in this embodiment are made of ethylene-propylene-diene rubber, however in other embodiments other materials, such as butadiene-acrylonitrile rubber or fluorocarbon rubber can be used.

It is obvious that the invention can be executed in many different embodiments without departing from its relevant subject-matter, and therefore also in such arrangement when the body 2 and the cover 12 are made of plastics and the other elements or some selected elements are made of metal.

Embodiment of the balancing valve 1 according to the invention allows to achieve several goals simultaneously. It contributes to reduction of production costs and improves corrosion resistance of the components of the valve 1, while, due to the properties of the material used to make the head 6 and the adjusting ring 13, it allows for self-adjustment of matching of the head 6 with the adjusting ring 13 to the seat 5 of the valve resulting from the flexibility of the plastics. At the same time, it allows smooth and highly accurate adjustment of the flow parameters.