The present invention relates to a valve of the type set forth in detail in the preamble of claim 1.

In case such a valve is mounted in a pipe line circuit with a flow of water or air, the pressure on the inlet side of the valve being higher than on the outlet side of it , a driving power of the fluid is obtained, a flow through the valve resulting. The flow amount is dependent on the size of the driving force, which shows itself in the differential pressure across the valve, and the size of the opening area between the valve body and the valve seat.

The ratio of the maximum adjustable flow and the minimum adjustable flow for a constant differential pressure across the valve is called the adjustment area of the valve or the adjustment ratio. The size of the adjustment area is a function of the ratio between the largest and the smal¬ lest opening area between the adjustment body and the valve seat. In a construction of the above-described type the ad¬ justment area, due to manufacturing technical reasons, will be limited to 100:1 - 200:1.

In e.g. plants for hot tap water in central heating sys¬ tems, in which the decrease in pressure of the regulated valve is relative low, e.g. about 100 KPa in summer, and the feeding temperature is about 65 C, a valve having a certain capacity value is selected. In winter the decrease in pressure of the feeding is substantially higher, e.g. as high as 1000 KPa, and the feeding temperature is higher than in summer. Thus, the selected valve will have a too large capacity in winter. A circulation pump is used in multiple-family houses, which circulates the hot water in the pipes, when no tapping takes place, in the night¬ time as well as in the daytime. The hot water circulation is designed to compensate for the heat losses in the hot water system. With a view to having the valve regulate

from the largest required flow down to the smallest re¬ quired flow the regulation area preferably will be larger than 300:1. This is not possible to achieve, according to experience, using just one valve or regulation body.

In order to obtain a larger regulation area having a more precise regulation of a fine area the use of so called split range valves is already known, two regulation valve bodies being connected to obtain a sequential control or two comp¬ lete valves being mounted in a pipe circuit for the same purpose. SE-B-414 960 and SE-B-456 689 show such already known valves.

The already known valves also mainly function in the de¬ sired way, but partly they do not produce a sufficiently exact and even fine regulation, and partly they do not have a satisfactory regulation characteristic in the transition area from a fine to a coarse regulation.

DE-C-152 868 and SE-B-357422 show additional known tech¬ nique. DE-C-152 868 relates to a steam valve with double cones on a common spindle and is designed to avoid steam leakage, which in course of time tends to increase. Accor¬ ding to Fig. 1 the cones are mounted on a common spindle. The lower cone is connected to the valve spindle. The upper cone is axially movable on the valve spindle. By means of a spring the upper cone is prestressed in order to obtain a satisfactory sealing of the two cones. Figs. 4 and 5 show other variants of the design shown in Fig. 1. An elastic element according to Fig. 5 is designed to avoid that only the one cone bears on the valve seat and a leakage occurs at the other cone. The patent claims relate to a cone valve, which is self-sealing against steam. The inventive concept is that the steam will enter the cavity between the two cones, in which cavity the steam will be transformed from the steam phase to the liquid phase. When the cavity has been filled with a condensate, a satisfactory steam sea¬ ling has been obtained. This construction is designed to

achieve a leakproof valve and not a construction, designed to allow a regulation of the valve.

SE-B-357 422 relates to a steam regulation valve having two coaxially disposed valve cones, each one being cont¬ rolled by its regulation element, which regulation ele¬ ments are operated individually. The advantage of such a valve is supposed to be that two valves are mounted in one valve body, which is advantageous if there is a lack of space. Also, this valve construction is supposed to allow a simpler pipe connection than when two valves are used. The object of this invention is not enhance the cont¬ rollability of a valve by means of the two coaxially dis¬ posed cones.

The object of the present invention is to, as regards the above-mentioned considerations, improve the already known valves and also in additional respects to develop the state of the art in this field, through a construction, which is more expedient as regards e.g. its manufacturing and/or mounting and/or its maintenance and life as well as ex¬ penses.

This object is achieved according to the present invention by designing a valve of the type described above mainly in the way set forth in the characterizing clause of patent claim 1.

Additional characterizing features and advantages of the invention are stated in the following description, refe¬ rence being made to the accompanying drawings, which illustrate a few preferred but not limiting embodiments. The drawings show in detail:

Fig. 1 a valve according to the invention in its comple¬ tely closed position in a mainly diametrical section; Fig. 2 a and b an enlarged partial view of the valve ac¬ cording to Fig. 1 with a partially open fine regulation

and an at least partially open coarse regulation; Fig. 3 a modified valve design according to the invention in a view corresponding to a portion of Fig. 1 and in a sec¬ tional view along line A-A in the same figure respectively, and with a flow diagram respectively;

Fig. 4 an additional modified valve design according to the invention in a view corresponding to Fig. 3, and a matching flow diagram;

Fig. 5 a valve design according to a portion of Fig. 1, the small valve being at a maximum and the large valve still being closed, and the matching diagram; and Fig. 6 a diagram showing the ratio between the stroke and the opening area of a small valve according to Figs. 1, 2 and 5.

The valve according to the present invention is suited for use in two-way as well as multiple-way constructions. Also, several valves according to the invention can be connected in series, the valve bodies being opened and closed respec¬ tively in the same direction or in the opposite direction, i.e. the valve bodies being oriented in the same direction or with a mirror-symmetrical orientation.

In Fig. 1 a manual, electromagnetic, electrohydraulic, pneu¬ matic or magnetic adjusting element 1 is shown, which is attached to a valve shoulder 2, which in its turn, bymeans of threaded bolts 3 and nuts 4 is attached to a valve body 5, the two portions of the shoulder and the body respec¬ tively facing each other and being designed as flanges 6 and 7 respectively with an intermediate seal 8.

Adjusting element 1 comprises a spindle 9, which extends along the center line of valve body 5 and which within the valve shoulder is surrounded by a packing box 10, which is locked by a safety ring 11, inserted in a groove 12 in a central bore 13 in the shoulder.

Valve body 5 is in the shown embodiment a two-way construc¬ tion having an inlet 14 and an outlet 15, which are sepa¬ rated by a partition wall 16, in the central part of which in an opening 17 a sleeve 18 is inserted, which forms a valv seat 19 at its end which faces the outlet. This seat is de¬ signed to allow large flows and consequently also a coarse regulation. Sleeve 18 suitably has a reduced diameter with¬ in the seat area, e.g. by combining a mainly radial sur¬ face 20 and in a connection inwards a bevel 21 around the sleeve. In this way irregularities, an adherence of foreign particles and leakage caused thereby are avoided more re¬ liably.

The free end of spindle 9 extends all the way into the cent¬ ral part of sleeve 18 and supports within the area of seat 19 a valve body 22, which can also be called a coarse re¬ gulation body. The latter bears at the outlet area on seat 19 with a flange 23 and is provided inside the flange with a cone 24, the sides of which are parabola-shaped in an ax¬ ial section, whereas its free end is designed as a radial end surface 25. The diameter of the cone is at the shoulder or at the surface of flange 23, which faces the cone, rough¬ ly the same as the inner diameter of passage 26, which ex¬ tends through body 18. The parabola-shaped or possibly straight conical outer surface of the cone is designed/di¬ mensioned according to the desired regulation characteris¬ tic.

Regulation body 22 is axially displaceably mounted on spindle 9 and is for this purpose provided with a central axial through bore 27 having roughly the same inner diame¬ ter as the outer diameter of the spindle. The spindle pro¬ jects with its free end out of this bore and is outside body 22 provided with a stop 28, which is designed to act on and lift the regulation body, when the spindle is re¬ tracted/lifted (see Fig. 2b) but allow a spindle movement downwards beyond the closing position for regulation body

22 (see Figs . 1 and 2a) .

On top of flange 23 a helicoidal compressive spring 29 is mounted, which with its one end concentricly surrounds the spindle, whereas the other end of the spring is pressed against a stopping disc 30, which is fastened to the spindle by fastening means 31 and 32, which are inserted in grooves 33 and 34 respectively in the spindle in the direction of packing box 10. Spring 29 is designed to push regulation body 22 into a sealing contact against seat 19. In order to secure the spring against a transverse displacementdisc 30 and flange 23 can be provided with annular recesses 35 and 36 respectively in their opposite surfaces. When regu¬ lation body 22 is lifted from its seat 19, spring 29 will push it into contact with stop 28.

In accordance with another important feature of the pre¬ sent invention the free end of spindle 9 is designed as a valve body 37, which also can be called a fine regulation body. The spindle is for this purpose designed with prefe¬ rably one recess, in its entirety designated 38, which mainly is located inside bore 27. Recess 38 may be divi¬ ded into several different sections. In the area of flange

23 and possibly the shoulder area of cone 22 the recess suitably is designed as a cut parabola-shaped surface 39, which extends towards the free end of the spindle, oblique¬ ly and inwardly and to which an axial surface 40 is connec¬ ted, which according to Figs. 1, 2 and 5 is connected to a cylinder surface 41, having a reduced diameter, up to the free end surface of the spindle, an annual gap 42 being formed jointly with the lower part of bore 27 in the area of this cylinder surface, said gap being open downwards. The recess in this way can be made easily, quickly and simply and an additional simplification is possible in case, according to Figs. 3 and 4, axial surface 40 extends all the way to the free end of the spindle. Surface 39 is very important, since its parabola-shape allows a point-

shaped opening up of this small valve, an extremely exact fine regulation being possible. The seat for this small valve is the upper end or the end close to the outlet of bore 27, with which the spindle can interfere somewhat with a not reduced diameter or in which there is a cylinder- shaped recess 43 in the end surface of coarse regulation body 22, connected to the outlet, against bottom 44 of which recess is pressed a substantially cylinder-shaped sealing body 45, which encases the spindle, end surface 47 of which, which is reduced by a bevel surface 46 around the spindle, sealingly is pressed against said bottom. In this case the parabola-top of surface 39 can also be loca¬ ted within roughly the same plane as bottom 44 and end surface 47, when the small valve is fully closed. Surf c- ces 44 and 47 suitably are finely ground in order to im¬ prove the efficiency of the additional sealing surface, which is produced in this way. Sealing body 47 is retained by an upper stop ring 48 and is sealed against the spindel by an 0-ring 50, which is inserted inside the body in an annular groove 49 in the spindle. Mutually opposite sur¬ faces 19, 23 and 24 are also finely ground.

Such a valve works in the following way: According to Fig. 1 the two valve bodies 22 and 37 (45) are pressed against their respective seats and no flow occurs between the inlet and the outlet. According to Fig. 2a spindle 9 has been lifted slightly and via seat 51 of the small valve and point to sector-shaped opening 52, lo¬ cated inside said seat, a fluid can flow from the inlet to the outlet. The opening area of the small valve is shown in Fig. 6. The flow is shown in Figs.3-5. The diagram shows the substantial evenness of the opening area along the entire stroke of e.g. 4 mm of valve body 9, 37, the area of opening 52 increasing continuously from 0 to e.g. 4 mm 2. When the small valve is open fully according to Fig.

5, stop 28 bears on end surface 25 of body 22 and lifts, when the valve spindle movement continues, the coarse re-

gulation body from its seat and uncovers a coarse regula¬ tion opening 53, which continuously grows. See Fig. 2b and the right-hand side of the diagram in Fig. 5. However, it must be interposed in this connection , that the central part of said diagram, which part forms an even and imper- cetible transition between the small and the large valve or between the fine and the coarse regulation, is the re¬ sult of an additional important feature of the invention, which feature is illustrated as an embodiment in the upper part of Fig. 5, showing from below the central part. It is shown that stop 28 is designed as a restriction element, which covers three quarters of gap 42 in the contact posi¬ tion. The restriction element is an open flat ring and con¬ sequently it is C-shaped and is retained by e.g. lugs 54, pressed from spindle 9. Since gap 42 extends around the en¬ tire spindle, the location of opening 55 of restriction element 28 is not critical, i.e. this element can be rota¬ ted to another position than the one shown in Fig. 5 with¬ out influencing the diagram according to Fig. 5. The cross- sectional area of gap 42 is in a practical embodiment about

2

18 mm and three quarters of it is covered, when restric¬ tion element 28 bears on the spindle end, thus only about

2

4.25 mm being opened for the free flow, i.e. a third valve is obtained, which chokes in the opening end phase of small valve 37,51 in such a way, that the opening areas of the two last-mentioned valves increasingly will have the same size and finally will have roughly the same size. In this way a temporary flow increase, which otherwise in praxis is unavoidable and is shown in the central part of the diagram according to Fig. 3, can be avoided. As is shown, a temporary levelling-off of the flow curve follows this flow increase, before the flow again increases in a con¬ tinuous and even way. Thus, thanks to the described fea¬ tures according to the invention it is possible to avoid temporary flow irregularities. The result is much better than expected, since it is not evident from the curve in Fig. 5, that two and three different valves respectively

are used successively and are responsible for the curve in its entirety.

The features of the invention, described above and illust¬ rated in the drawings as embodiments, are based on the re¬ alization, that flow irregularities, in the two directions, i.e. a temporary flow increase and a subsequent flow de¬ crease are unavoidable, when a small valve is designed for a continuously increasing flow, which subsequently, when the flow is at a maximum, is added to an initial flow through the large valve. The value of the small flow, which has been forced up to a maximum, is subsequently followed by a corresponding flow decrease, as the large flow has got started, and the fall of pressure across the small valve levels off in a way which the large valve cannot make up for. Of couse, the same negative effect occurs during a flow decrease from an open large flow down to a small flow and a shut-off. In accordance with the invention it is possible to forestall and render harmless the anticipated flow increase by means of said restriction, which also is prepared for the flow decrease, which follows the flow in¬ crease, the flow decrease occurring earlier. Consequently, in the other direction, i.e. during a flow decrease through the entire valve, during the transition from the large flow to the small flow, actually a decrease of the flow restric¬ tion at the third valve 27,28,42 occurs, and a similar flow pattern is obtained in this direction.

The angle of surface 39 in relation to the longitudinal axis of the spindle can be as high as 5-45 , preferably about 14 . Instead of being directly connected to sealing body 45 this surface can also be positioned at a distance from or be slightly covered by this body, depending on the desired flow characteristic. Of course, surface 39 can have another shape than being flat or parabola-shaped. A convex and/or concave design in the circumferential direction of the spindle and/or in its axial direction is possible. Al-

so, the second and/or the third valve can be a separate part, which is attached to the spindle, if it is desirable to avoid a machining of the spindle and to take advantage of other materials having other properties, e.g. plastic materials, respectively.

It is shown in Figs.3 and 4, that the design of stop/rest¬ riction element 28 is important for the flow pattern. In Fig. 3 element 28 is designed as a pin, which is positioned right through the spindle and does not have any substantial restriction properties. The flow pattern in Fig. 3 indi¬ cates clearly a substantial temporary flow increase and a following flow decrease during the transition from the small to the large valve or more particularly during the final phase of the fine regulation and the intial phase of the coarse regulation.

In Fig. 4 stop element 28 is designed as a closed disc, which, when the small valve is opened up at a maximum, comp¬ letely shuts off the flow to it. In this case a "dip" is ob¬ tained in the opposite direction as compared to the bulge shown in Fig. 3. The two flow characteristics are of course equally objectionable during normal operations and of course difficult to overcome as regards the control aspects. However, openings in the disc can be used in order to coun¬ teract the inferior flow characteristics. The openings can be designed in an arbitrary way and be located in arbitrary places in the disc and/or in the lower part of body 22.

Also, it ought to be mentioned, that the stroke of the course regulation body in the described practical embodi¬ ment suitably is about 18 mm. The stroke of the fine regu¬ lation body suitably is 2-10 mm, preferably about 4 mm. The diameter of bore 27 suitably is 10 mm, whereas the dia¬ meter of cylinder 41 may be as high as 8.8 mm, according to a practical and not limiting embodiment. Consequently, gap width 42 suitably is 0.6 mm. The overlapping, which

exists between bore 27 and cylinder surface 41, can be as high as e.g. 2 mm, when the small valve is completely open, and e.g. 20 mm, when the small valve is completely closed. This means that the overlapping area generally will be mul¬ tiplied during the closing movement of the small valve. This large increase of the overlapping area, within which gap width 42 is comparatively small, e.g. 0.6 mm, results in an increased friction and turbulence, which produces a choking effect on the flow. Stop element 28, when located in the contact position, will also produce a choking effect due to a shielding effect. Thus, the term "choking" includes a friction or turbulence increase effect, e.g. due to an in¬ crease in the contact surface between the passages and the flowing liquid. Fine regulation opening 52 is of course comparatively compact and consequently has a small friction. Thus, it is comparatively easy to increase the flow through this opening by increasing its area but keeping its cha¬ racteristics. On the other side the gap cross-sectional area is never decreased, but the gap is lengthened, a flow stabilizing increase of the friction factor being obtained, which in the final phase for the maximum opening up of the small valve is supplemented by a shielding factor due to the preferably partial shielding of gap 42 by means of stop element 28. In this way a smooth regulation area transi¬ tion is obtained, as is shown in the diagram in Fig. 5.