BUTTERFLY VALVE

Abstract

A butterfly valve comprises a seat ring (1), a centered valve disc (3) and a valve axis (16). The seat ring (1) and the valve disc (3) are constructed to co-operate as first and second elements of a seal for sealing a volume in which the valve axis (16) is located from internal volume of the valve. The seal is substantially a radial-force-type seal with respect to the valve axis (16). The torque for opening or closing the valve is not more than 160 Nm. The invention relates further to an actuator for a butterfly valve comprising either a voltage detection and/or a temperature and/or humidity controller and/or a safety subsystem to prevent fire in the case of fault conditions. The invention relates further to a hand crank detection system for a butterfly valve, a position indicator for a butterfly valve and an adapter between a butterfly valve and its actuator.

Claims

1. A butterfly valve comprising a seat ring, a centered valve disc and a valve axis, wherein a) the seat ring and the valve disc are constructed to co-operate as first and second elements of a seal for sealing a volume in which the valve axis is located from internal volume of the valve, b) the seal is substantially a radial-force-type seal with respect to the valve axis, characterized in that c) the torque for opening or closing the valve is not more than 160 Nm.

2. A butterfly valve comprising a seat ring, a centered valve disc and a valve axis, wherein a) the seat ring and the valve disc are constructed to co-operate as first and second elements of a seal for sealing a volume in which the valve axis is located from an internal volume of the valve, b) the seal is substantially a radial-force-type seal with respect to the valve axis, characterized in that c) the elements are constructed to limit a sealing pressure to a slim line.

3. A butterfly valve according to claim 1, characterized in that a) a first contacting surface associated with the first element is convex-shaped and rounded in a radial cross-section with respect to the valve axis and b) a second contacting surface associated with the second element is cone-shaped in a radial cross-section with respect to the valve axis.

4. A butterfly valve according to claim 2, characterized in that a) a first contacting surface associated with the first element is convex-shaped and rounded in a radial cross-section with respect to the valve axis and b) a second contacting surface associated with the second element is cone-shaped in a radial cross-section with respect to the valve axis.

5. A butterfly valve according to claim 1, characterized in that a) the contacting surfaces of both elements are rounded in a radial cross-section with respect to the valve axis.

6. A butterfly valve according to claim 2, characterized in that a) the contacting surfaces of both elements are rounded in a radial cross-section with respect to the valve axis.

7. A butterfly valve according to claim 3, characterized in that of the first and/or the second contacting surface is rounded in a radial cross-section with respect to the valve axis and encircles the valve axis completely at a predetermined axial position with respect to the valve axis.

8. A butterfly valve according to claim 5, characterized in that of the first and/or the second contacting surface is rounded in a radial cross-section with respect to the valve axis and encircles the valve axis completely at a predetermined axial position with respect to the valve axis.

9. A butterfly valve according to claim 4, characterized in that of the first and/or the second contacting surface is rounded in a radial cross-section with respect to the valve axis and encircles the valve axis completely at a predetermined axial position with respect to the valve axis.

10. A butterfly valve according to claim 6, characterized in that of the first and/or the second contacting surface is rounded in a radial cross-section with respect to the valve axis and encircles the valve axis completely at a predetermined axial position with respect to the valve axis.

11. A butterfly valve according to claim 3, characterized in that a cone-shaped contacting surface is formed such that the contacting surface comes closer to the co-operating element with increasing radial distance with respect to the valve axis.

12. A butterfly valve according to claim 4, characterized in that a cone-shaped contacting surface is formed such that the contacting surface comes closer to the co-operating element with increasing radial distance with respect to the valve axis.

13. A butterfly valve according to claim 3, characterized in that the cone-shaped contacting surface is associated with the valve disc and the convex-shaped and rounded contacting surface is associated with the seat ring.

14. A butterfly valve according to claim 4, characterized in that the cone-shaped contacting surface is associated with the valve disc and the convex-shaped and rounded contacting surface is associated with the seat ring.

15. A butterfly valve according to claim 3, characterized in that the rounded contacting surface of at least one element is part of a protrusion of said element towards the co-operating element, preferably the protrusion is a protrusion of the seat ring which protrudes towards the valve disc.

16. A butterfly valve according to claim 5, characterized in that the rounded contacting surface of at least one element is part of a protrusion of said element towards the co-operating element, preferably the protrusion is a protrusion of the seat ring which protrudes towards the valve disc.

17. A butterfly valve according to claim 4, characterized in that the rounded contacting surface of at least one element is part of a protrusion of said element towards the co-operating element, preferably the protrusion is a protrusion of the seat ring which protrudes towards the valve disc.

18. A butterfly valve according to claim 6, characterized in that the rounded contacting surface of at least one element is part of a protrusion of said element towards the co-operating element, preferably the protrusion is a protrusion of the seat ring which protrudes towards the valve disc.

19. A butterfly valve according to claim 16, characterized in that the protrusion including the rounded surface is the region closest to the valve disk.

20. A butterfly valve according to claim 18, characterized in that the protrusion including the rounded surface is the region closest to the valve disk.

21. A butterfly valve according to claim 16, characterized in that in at least one radial cross-section with respect to the valve axis, the distance between the seat ring and the valve disc does not decrease along a line starting from the point with the smallest distance between seat ring and valve disc on the protrusion and moving away from the valve axis in radial direction.

22. A butterfly valve according to claim 18, characterized in that in at least one radial cross-section with respect to the valve axis, the distance between the seat ring and the valve disc does not decrease along a line starting from the point with the smallest distance between seat ring and valve disc on the protrusion and moving away from the valve axis in radial direction.

23. A butterfly valve according to claim 16, characterized in that there is a second protrusion protruding in radial direction towards the valve axis, which stabilizes the position of the protrusion and which seals a first volume between the valve disc and the valve axis from a second volume between a valve body and the valve axis.

24. A butterfly valve according to claim 18, characterized in that there is a second protrusion protruding in radial direction towards the valve axis, which stabilizes the position of the protrusion and which seals a first volume between the valve disc and the valve axis from a second volume between a valve body and the valve axis.

25. A butterfly valve according to claim 23, characterized in that there is a third protrusion, protruding in radial direction towards the valve axis and which is further away from the valve disc than the second protrusion and which seals a second volume between the valve body and the valve axis from a third volume between the valve axis and an outside or a valve actuator.

26. A butterfly valve according to claim 24, characterized in that there is a third protrusion, protruding in radial direction towards the valve axis and which is further away from the valve disc than the second protrusion and which seals a second volume between the valve body and the valve axis from a third volume between the valve axis and an outside or a valve actuator.

27. A butterfly valve according to claim 25, characterized in that the third protrusion is at least partially shaped like an O-ring.

28. A butterfly valve according to claim 26, characterized in that the third protrusion is at least partially shaped like an O-ring.

29. A butterfly valve according to claim 1, characterized in that the seat ring is composed of elastomer and the valve disk is composed of a less flexible material than the seat ring, preferably of steel.

30. A butterfly valve according to claim 2, characterized in that the seat ring is composed of elastomer and the valve disk is composed of a less flexible material than the seat ring, preferably of steel.

31. Adapter for the connection of a butterfly valve axis to an actuator which comprises an actuator receiving element and an axis receiving element whereby a) The actuator receiving element is mounted to or is a part of an actuator and b) The axis receiving element is mounted to or is a part of a valve body and c) The actuator receiving element and the axis receiving element can be detachably connected to each other, preferable by having form-fitting shapes and screws to fix a position relative to each other and d) The axis receiving element comprises a. a bottom and a top part b. Whereby the bottom part surrounds the valve axis and c. Whereby the top part comprises four sections, each of approximately 90, whereby two sections, being on opposite sides of the valve axis, comprise axis-receiving-element-protrusions and the other two sections are empty. e) The actuator receiving element comprises preferably d. Two base sections which can receive the axis-receiving-element-protrusions of the axis receiving part at least partially.

32. Actuator for a butterfly valve, characterized in that it comprises voltage detection means which are coupled to a variable input resistance such that the voltage available to the circuit connected in parallel to the resistance has a given value independent of the input voltage, preferable for input voltages between 19 V and 265 V AC or DC.

33. Actuator for a butterfly valve, characterized in that it comprises a temperature and/or humidity controller which comprises a) One or more sensors for temperature and/or humidity and b) One or more heaters c) Whereby the heaters are controlled depending on the sensor measurements in order to avoid condensation of humidity in or on the actuator and/or in order to prevent frost in or on the actuator or movable parts close to it.

34. Actuator for a butterfly valve, characterized in that it comprises a safety subsystem which protects the actuator from risk of fire in fault conditions and which comprises electronic hardware and software running on and controlling the electronic hardware, whereby the software comprises three parts: a bootstrapper, a boot-loader allowing software updates in boot mode and the actual safety firmware.

35. Hand crank detector for a butterfly valve, characterized in that there is an IR light barrier inside a socket for a hand crank which gives out a signal which prevents the operation of an actuator for a butterfly valve if the IR barrier is disturbed.

36. Indicator for the position of a butterfly valve disc, characterized in that it comprises a flexible stick which can be coupled to a valve axis of the butterfly valve and which is oriented in the same way as the valve disk in every position the valve disc can be in.

37. A flow regulating device comprising a) a butterfly valve comprising a valve disc which is rotatable, and b) an actuator, and c) an actuator control unit designed to control the actuator for bringing the butterfly valve into a closed state, whereby, when closing the valve, the actuator rotates the valve disc inside a defined interval of rotation angles until either a predefined fixed maximum value of torque is reached or the end point of the defined interval of rotation angles is reached.

38. A flow regulating device according to claim 37, wherein the butterfly valve comprises a seat ring, a centered valve disc and a valve axis, wherein a) the seat ring and the valve disc are constructed to co-operate as first and second elements of a seal for sealing a volume in which the valve axis is located from internal volume of the valve, b) the seal is substantially a radial-force-type seal with respect to the valve axis, characterized in that c) the torque for opening or closing the valve is not more than 160 Nm.

39. An actuator control unit designed to control an actuator of a butterfly valve a) whereby the actuator is capable of rotating a valve disc of the butterfly valve b) and whereby the actuator control unit, when closing the valve, makes the actuator rotate the valve disc inside a defined interval of rotation angles until either a predefined fixed maximum value of torque is reached or an end point of the defined interval of rotation angles is reached.

40. An actuator control unit according to claim 39 whereby the butterfly valve comprises a seat ring, a centered valve disc and a valve axis, wherein a) the seat ring and the valve disc are constructed to co-operate as first and second elements of a seal for sealing a volume in which the valve axis is located from internal volume of the valve, b) the seal is substantially a radial-force-type seal with respect to the valve axis, characterized in that c) the torque for opening or closing the valve is not more than 160 Nm.

41. An actuator control unit according to claim 39 whereby the butterfly valve comprises a seat ring, a centered valve disc and a valve axis, wherein a) the seat ring and the valve disc are constructed to co-operate as first and second elements of a seal for sealing a volume in which the valve axis is located from an internal volume of the valve, b) the seal is substantially a radial-force-type seal with respect to the valve axis, characterized in that c) the elements are constructed to limit a sealing pressure to a slim line.

42. Method for controlling the closing of a butterfly valve comprising a valve disc which is rotatable by an actuator, whereby, for closing the butterfly valve, the actuator rotates the valve disc until a predefined fixed maximum value of torque is reached and if this predefined fixed maximum value of torque is not reached before the valve disc has turned to an end point of a defined interval of rotation angles, the rotation is stopped at this end point.

43. Method for controlling the closing of a butterfly valve according to claim 42, comprising the steps of: a) Determining if the torque applied by the actuator is smaller than a predefined fixed maximum value of torque b) If this is the case, determining if the position of the valve disc is smaller than a maximum position c) If this is the case, increasing the torque and repeating steps a), b) and c).

44. A method according to claim 42 for closing a butterfly valve comprises a seat ring, a centered valve disc and a valve axis, wherein a) the seat ring and the valve disc are constructed to co-operate as first and second elements of a seal for sealing a volume in which the valve axis is located from internal volume of the valve, b) the seal is substantially a radial-force-type seal with respect to the valve axis, characterized in that c) the torque for opening or closing the valve is not more than 160 Nm.

45. A method according to claim 42 for closing a butterfly valve comprises a seat ring, a centered valve disc and a valve axis, wherein a) the seat ring and the valve disc are constructed to co-operate as first and second elements of a seal for sealing a volume in which the valve axis is located from an internal volume of the valve, b) the seal is substantially a radial-force-type seal with respect to the valve axis, characterized in that c) the elements are constructed to limit a sealing pressure to a slim line.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0128] The drawings used to explain the embodiments show:

[0129] FIG. 1a-d Cross-sections of a seat ring.

[0130] FIG. 2 A cross-section of a valve disc.

[0131] FIG. 3 A cross-section of a seat ring, a valve disc and a valve axis in the mounted arrangement.

[0132] FIG. 4 A butterfly valve with an adapter and a position indicator in the open position.

[0133] FIG. 5 A butterfly valve with adapter, position indicator and actuator in the closed position.

[0134] FIG. 5b An actuator receiving element of an adapter.

[0135] FIG. 6 Voltage detection and correction means.

[0136] FIG. 7 A hand crank detector for a butterfly valve.

[0137] FIG. 8 Safety subsystem of an actuator for a butterfly valve.

[0138] FIG. 9 The complete butterfly valve assembly.

[0139] FIG. 10 Flow chart of the control algorithm for closing the valve.

[0140] In the figures, the same components are given the same reference symbols.

PREFERRED EMBODIMENTS

[0141] FIG. 1a shows a cross-section of a seat ring 1 for a butterfly valve. The plane of the cross-section passes through the middle of one of the two holes 39 for the valve axis 16. The flow direction 40 (FIG. 4) of the fluid and the rotation axis 14 of the valve disc 3 also lie in the plane of the cross-section. The orientation of the cross-sectional plane is indicated in FIG. 1d, which shows the seat ring 1. The orientation of the cross-sectional plane shown in FIG. 1a is labelled A.

[0142] The seat ring 1 shows three protrusions: One of them, the protrusion 9, extends into the main volume of the valve while a second protrusion 10 extends in radial direction 38.2 (FIG. 2) in the hole 39 for the valve axis. A third protrusion 11 extends also in radial direction 38.2 (FIG. 2) in the hole 39 for the valve axis.

[0143] Apart from the protrusion 9 and outside of the hole 39 for the valve axis, the surface of the seat ring 1 has in this cross-section approximately a U-shape which is wider than high. On the highest ends 1.4 of the U, there are fixing protrusions 1.1, 1.2 and 1.3, one to the inside (1.3) and two to the outside (1.1 and 1.2) of the U-shape. The fixing protrusions 1.1, 1.2, 1.3 are used to fix the seat ring 1 to the valve body 2.

[0144] When the cross-sectional plane is rotated around the flow direction of the liquid 40 (FIG. 4) the shape of the seat ring 1 in these new cross-sections changes. This is shown in FIGS. 1b and 1c. The orientations of the cross-sectional plane is shown in FIG. 1d and it is labelled B. Outside the holes 39 for the valve axis and the surrounding protrusion 9, the shape of the lower part of the U becomes more pentagon-like 1.5. The corner points 1.51 and 1.52 of this pentagon are the two points on the baseline of the U (base points). The third point 1.53, the forth point 1.54a and the fifth point 1.54b are placed further inside the main volume of the valve. The distance between one of the base points 1.51 or 1.52 and the third point 1.53 changes. The location of the third point is shown in FIG. 1a, b by a slightly curved line approximately in the middle of the seat ring 1.

[0145] FIG. 1c shows the complete cross-section B as indicated in FIG. 1d. In this view, it becomes clear how the position of the third 1.53, forth 1.54a and fifth 1.54b corner point of the pentagon changes along the seat ring 1.

[0146] FIG. 1b shows a detail of FIG. 1c and therefore the description of FIG. 1b applies for FIG. 1c, too. FIG. 1c shows further the hole 39 for the valve axis: it is the round hole in the center. The distance between the two corner points 1.51 and 1.52 is constant along the seat ring. With increasing distance from the center, the third point 1.53 of the pentagon-like shape comes closer to one of the corner points 1.51 or 1.52 and therefore away from the other corner point 1.52 or 1.51.

[0147] In FIG. 1a, the hub-area can be seen in detail: The protrusion 9 extends a certain height H into the inner part of the valve. In the cross-section, it has a shape which is a combination of a circle segment 9.2 and maybe also a rectangle 9.1. If one rotates the cross-section around the rotation axis 14 of the valve axis, this shape is in every one of these cross-sections very similar. Differences exist only in the region where the protrusion 9 goes over to the seat ring 1 outside the protrusion 9. The circle segment can have a radius R different from the height H, preferably a radius R is larger than the height H. The protrusion 9 is a contacting surface.

[0148] The second protrusion 10 extends towards the valve axis 16 at the position of the protrusion 9. Here the second protrusion 10 is shown to be approximately rectangular in the cross-section. The second protrusion 10 surrounds the valve axis 16.

[0149] The third protrusion 11 is O-ring like. It has an essentially semi-circular shape in the cross-section. The third protrusion 11 is located on the surface of the seat ring 1, oriented towards the valve axis 16. It is further away from the main volume of the valve than the second protrusion 10.

[0150] FIG. 2 shows a valve disc 3 which can form a seal together with the seat ring 1 shown in FIG. 1. In the cross-section shown, the valve disc 3 has an essentially circular shape. FIG. 2 shows only the upper part of the valve disc 3. Along the rotation axis 14 of the butterfly valve, there is an opening 12 for the valve axis. This opening 12 is essentially of cylindrical shape, however, it is not everywhere a circular cylinder but at least in part a not-circular cylinder. In the exit region of the opening for the valve axis 12, there is a cone-shaped indentation 13. The cone-shaped indentation 13 is not a complete cone, but only part of the surface of a cone. This cone has a half opening angle 15 and is centered along the rotation axis of the valve 14. The cone-shaped indentation 13 is a contacting surface.

[0151] FIG. 3 shows the seat ring 1, the valve disc 3, the valve body 2 and the valve axis 16 in the mounted state. Note that the seat ring 1 shown in FIG. 3 is not exactly the same embodiment as the one shown in FIG. 1. The seat ring 1 in FIG. 3 does not have a second and a third protrusion 10, 11. Instead, the opening for the valve axis is designed such that it forms a seal together with the valve axis 16. There is a region close to the valve axis 16 where the protrusion 9 of the seat ring 1 and the cone-shaped indentation 13 of the valve disc 3 overlap. In reality, this overlap is not possible but results in a high pressure between seat ring 1 and valve disc 3 and a deformation of the seat ring 1. This high pressure contact secures the function of a seal.

[0152] FIG. 4 shows the assembled butterfly valve without actuator. The valve body 2 has essentially the shape of a short tube. There are connecting elements for the connection with pipes on the input and output of the valve. There are further cylinders extending from the top 2.1 and the bottom 2.2 of the valve body 2 which can receive at least parts of the valve axis 16. The seat ring 1 is located inside the valve body 2. Inside the seat ring 1 there is the valve disc 3. The valve disc 3 is kept in its position by the valve axis 16. The valve axis 16 extends through the cylinder 2.1 extending to the top. On this cylinder 2.1, an axis receiving element 4 of an adapter, consisting of the axis receiving element 4 and the actuator receiving element 5, is mounted. Preferably, there is a standard ISO flange on the cylinder 2.1 onto which the axis receiving element 4 can be mounted, e.g. with screws. This axis receiving element 4 has two parts: There is a bottom part 4a which is of circular shape and which is mounted to the cylinder 2.1 extending to the top. And there is a top part 4b comprising two axis-receiving-element-protruding sections 4b.1 and 4b.2 which hold screws 4c. The valve axis 16 passes through the adapter and is covered by a coupling device 7. Onto this coupling device 7, a position indicator 6 may be mounted.

[0153] The position indicator 6 has in its center a ring-like part which is on its inside formed complementary to the outside of the coupling device 7. From this ring-like part two sticks extend in directions opposite to each other. The sticks themselves are well visible and/or reflective. At the end of the sticks, well visible and/or reflective end pieces are connected. Preferably, the sticks are flexible and the end pieces are soft and flexible. A collision with the position indicator will make no harm.

[0154] The position indicator 6 is mounted on the coupling device 7 by pushing the ring-like part onto the coupling device 7. Due to the form-fit connection between the valve axis 16 and the coupling device 7 and the position indicator 6, the rotation of the valve axis 16 causes the rotation of the coupling device 7 which causes the rotation of the position indicator 6. Preferably, the position indicator 6 is mounted such that the sticks extend in the plane defined by the plane of the valve disc 3. Thereby, the sticks and the end pieces of the sticks indicate the position of the valve disc 3. The axis-receiving-element-protruding sections 4b.1 and 4b.2 occupy each one less or equal to 90 of the circle surrounding the rotation axis of the valve. This allows the position indicator 6 to move to all positions which occur during nominal operations of a butterfly valve.

[0155] FIG. 5 shows the same butterfly valve as FIG. 4 including the same valve body 2, the same seat ring 1 and valve disc 3. There is also the adapter shown. The adapter comprises the axis receiving element 4 and the actuator receiving element 5. The axis receiving element 4 is connected to an actuator receiving element 5. This connection is preferably a form fit connection secured and stabilized by a connection with screws 6. The actuator receiving element 5 is connected to the actuator 8 by being a part of the actuator housing. Preferably, there are only two screws 6 needed to stabilize the connection between the actuator receiving element 5 and the axis receiving element 4.

[0156] FIG. 5b shows the actuator receiving element 5, which is in this case a part of the actuator housing. Alternatively, the actuator receiving element 5 can be fixed to the actuator housing by suitable means as e.g. screws, adhesives, clip connections, bands and similar connections. In this view, the actuator receiving element is mirror symmetric about two perpendicular axis. We describe therefore only one quarter of it, although all four quarters are shown. In the center of this view of the actuator receiving element 5, there is the connection element to the coupling device 5.6. It is an indentation which a complementary shape to the coupling device 7 so that a form-fit connection between the connection element 5.6 and the coupling device 7 can be established by simply pushing the coupling device 7 into the connection element 5.6. The connection element is surrounded by a region which is lower than the other parts shown in this figure except for the connection element 5.6. This lower region is called indentation section 5.5. On the indentation section, there are actuator-receiving-element-base sections 5.2. They are located above the indentation section 5.5 and have an approximately triangle shape. The shape of the actuator-receiving-element-base sections 5.2 surface is approximately the same as the shape of the Axis-receiving-element-protruding sections 4b.1 or 4b.2. There is a screw receiving thread 5.1 on each one of the actuator-receiving-element-base sections 5.2 which can receive the screws 6 in order to fix the actuator receiving element 5 to the axis receiving element 4. In order to establish the form fit, the actuator receiving element 5 comprises further protrusions 5.4 which protrude between the actuator-receiving-element-base sections 5.2 and the Indentation section 5.5 which surrounds the connection element 5.6. The protrusions 5.4 are formed such that they can establish a form-fit connection with the axis-receiving-element-protruding sections 4b.1 and 4b.2. There are standard threads 5.3 in the protrusions 5.4 which can receive the screws which are used in a standard ISO connection between a valve flange and an actuator 8. Therefore, an actuator 8 with a housing that comprises an actuator-receiving-element 5 can be connected to a valve with a standard ISO flange or with an axis-receiving element 4.

[0157] FIG. 6 shows a diagram of the voltage detection means for control signals. On the left side there is the input 25 for control signals carries by AC or DC voltages between 19 and 265 V (effective voltage). The first box represents an electromagnetic interference filter unit (EMI) 26. The second box represents the voltage detection unit 27. The detected value from the voltage detection unit 27 enters the control of a variable input resistance 28. A forth box represents a current control unit 29. The current control unit 29 comprises two outputs: One goes to the control of the variable input resistance 28 and the other to a galvanically isolated unit 30. The galvanically isolated unit 30 converts the input signal into a digital output 31 of predefined voltage, current and waveform.

[0158] The EMI 26, the voltage detection unit 27, the variable input resistance 28 and the combination of current control 29 and galvanically isolated unit 30 are connected in parallel. The current control 29 and galvanically isolated unit 30 are connected in series.

[0159] FIG. 7 shows a hand crank detector for a butter fly valve. The hand crank, shown here with the parts 19, 20 and 24, can be inserted into the housing of the actuator 18. The hand crank itself comprises a housing 19, a position indicator 20 and an axis 24. The axis 24 is inserted into the housing of the actuator 18 and blocks thereby the light path between an IR-sender 23 and an IR-receiver 22. This blockage is detected by a suitable electronic board located inside the actuator housing 18 and this electronic board gives a signal to the actuator 8 not to block the valve against the motions caused by the hand crank.

[0160] In the mounted state, the hand crank housing 19 and the housing of the actuator 18 are connected with seals in between them. Thereby, no fluid or dirt from inside the actuator housing 18 can pass through the opening and, more important, nothing from the outside like e.g. dirt or water can enter the actuator housing 19.

[0161] The position indicator of the hand crank 20 allows the user to see immediately the position of the valve. A stopper 21, being formed or being connected to the actuator housing 18, prevents the user from applying unnecessary and potentially harmful pressure to an already closed valve.

[0162] FIG. 8 shows a safety subsystem. The safety subsystem is powered by the internal power supply 32 of the actuator. The power supply 32 transfers the power to the actuator 35 via a switch 33 and three field effect transistors (FET) 34. The FETs 34 are controlled by programmable controller 37. The programmable controller 37 receives measurements of three hall sensors which measure actuator parameters. The programmable controller 37 can connect the actuator 35 to the power supply 32 by commanding the control unit IEC 60730 36 to close the switch 33. The programmable controller 37 itself is directly connected to the power supply 32. Therefore, it can work independent of the power supplied to the actuator 35.

[0163] The number of hall sensors and FETs can be different from three, but preferably it is greater than zero.

[0164] In the case of failure of the safety subsystem, the switch 33 falls in its default position and disconnects the actuator 35 from the power supply 32. Preferably, the default position of the switch 33 is its open-position. In the case of strange or undesired actuator 35 behavior, the hall sensors detects this and the programmable controller 37 can either adapt the power given to the actuator 35 by controlling the FETs 34 differently or it can disconnect the actuator 35 from the power supply 32 completely by allowing the switch 33 to return to its default position. The software loaded onto the programmable controller 37 can be updated and parameters needed by the programmable controller can be updated, too. The software determines the reaction of the programmable controller on measurements and inputs.

[0165] FIG. 9, shows the complete setup comprising the valve body 2, the seat ring 1, the valve disc 3, the valve axis 16 (not visible as it is placed inside the valve disc 3 and the cylindrical extensions 2.1 and 2.2 of the valve body). There is further the adapter shown which comprises the axis receiving element 4 and the actuator receiving element 5, the position indicator 6 and the actuator 8. The actuator includes the voltage detection unit comprising the parts 25 to 31 and the safety subsystem including the parts 32 to 37.

[0166] FIG. 10 is a flow chart of the algorithm used to close the valve. The first step is a torque measurement 41. In the torque measurement step 41, the measured torque is compared to a reference value T.sub.max, in order to find out if the torque is equal to the reference value T.sub.max (T=T.sub.max) or below it (T<T.sub.max). Preferably, T.sub.max which is the reference value, is the predefined fixed maximum value of torque. Preferably T.sub.max is the maximum value of torque producible by the actuator and therefore T cannot be larger than T.sub.max. Therefore it is also possible, that the torque measurement step 41 determines TT.sub.max. However if the actuator can produce more torque, then the comparison should either decide if the torque is larger or equal to T.sub.max (TT.sub.max) or three options should be tested: T<T.sub.max; T=T.sub.max and T>T.sub.max.

[0167] In the case of the output being T=T.sub.max or TT.sub.max, the valve is considered to be in the close state 44.

[0168] In the case of the output being T>T.sub.max, there are two possibilities: either the valve is considered to be in the close state 44, too, or the torque is reduced until T=T.sub.max. Reducing the torque to the reference value safes energy and minimized material wear and is therefore preferred. However it requires more complicated control logic.

[0169] In the case of T<T.sub.max or TT.sub.max, a position measurement step 42 is entered. Here the position of the valve disc x is compared to a reference value x.sub.max. x should always be smaller or equal to x.sub.max. This can be ensured by the design of the seat ring and the disc. Therefore in one embodiment, possible outcomes of the position measurement step 42 are x=x.sub.max or x<x.sub.max. In a second embodiment, the possible outcome are x=x.sub.max or xx.sub.max. In a third embodiment, it is however also possible that the position measurement step 24 includes the determination of the states x>x.sub.max, x<x.sub.max and x=x.sub.max.

[0170] The states x<x.sub.max and xx.sub.max show that the final position is not yet reached and a torque increasing step 43 is entered.

[0171] In the state x=x.sub.max, the valve is considered to be in the close state 44.

[0172] In the state x<x.sub.max, the valve is probably broken as the disc has turned more than 90. Preferably, an error message is released and the actuator is turned off. There may be valve designs in which it is not a problem if the valve disc has turned that much, and where the actuator can be used to bring the disc in a desired position. A suitable control algorithm can be started at this point.

[0173] The torque increasing step 43 commands the actuator to increase the torque by a small amount and the algorithm enters the torque measurement step 41 again.

[0174] All comparisons can include tolerances. For example, the state T=T.sub.max can be reached for measured torques between T.sub.max.sub.1 and T.sub.max+.sub.2, whereby .sub.1 and .sub.2 can have the same or different values which are preferably small compared to T.sub.max. Preferably .sub.1 and .sub.2 are both less than 10% of T.sub.max, preferably .sub.1 and .sub.2 are both less than 1% of T.sub.max, preferably, similar considerations are true for the states TT.sub.max, T>T.sub.max, T<T.sub.max, x>x.sub.max, x<x.sub.max, x=x.sub.max and xx.sub.max. In summary, it is to be noted that the protrusion 9, the second protrusion 10 and the third protrusion 11 can have different shapes. For example the protrusion 9 and the second protrusion 10 may have a combined cross-section in the shape of a circle segment. The second protrusion 10 could have a similar cross-section as shown for the third protrusion 11 in FIG. 1. It is also possible that the protrusion 9 does not have a rounded part of the surface but that its cross-section has a triangular shape. Also the shape of the seat ring 1 outside these three protrusions can have a different shape.

[0175] Also the cone-shaped contacting surface 13 of the valve disc 3 does not need to be cone-shaped. For example, its cross-section may comprise a convex rounded part and/or circle segments. A rounded part is preferable if the protrusion 9 is not rounded in its cross-section.

[0176] The bottom part 4a of the axis receiving element 4 of the adapter does not need to have a circular cylindrical shape but it can also be a rectangular box. Its lower surface does not need to be parallel to its upper surface. The lower surface can for example, extend further downwards, surrounding the valve axis.

[0177] The valve body 2 can have a different shape. For example it can be longer or its upper and lower part can extend further along the valve axis. It is also possible that the connection elements to the pipes are designed differently.

[0178] The coupling device 7 can have a number of different shapes as long as it is not round. It can have for example a triangular cross-section, the shape of a cross or a blade or a polygon. It is also possible to use no coupling device 7 at all, but to connect the valve axis directly to the actuator 8 and possibly to the position indicator 6.

[0179] The actuator 8 can be mounted immediately to the valve axis 16 without any axis receiving element 4 or actuator receiving element 5.

[0180] The axis receiving element 4 and the actuator receiving element 5 can be connected by means other than form-fit connections and screws. For example bolts or click systems can be used or clamping straps as well as many other well-known connection systems.

[0181] The hand crank does not need to comprise a position indicator 20 and a stopper 21 or the position indicator 20 and stopper 21 can be designed in a different way. For example, a position indicator 20 can be a simple reference line drawn on the hand crank and/or on the housing which translates a hand crank position into a valve disc position.