The invention has been developed in its application to fluid valves of the butterfly type and of the gate type in which the movable member whose position has to be detected and remotely indicated is, respectively, a rotatable valve member and a slidable valve member, but is applicable to the detection and the remote indication of the position of any movable member which is adapted to angularly or linearly move between two end-of-travel positions.

The optical transducers according to the preamble of claim 1, also called optical encoders, are known from many years.

One of their advantages is that they are not sensitive to electromagnetic fields, temperature and humidity.

In these known transducers each pair of diodes facing each other is a separate unit which is provided with its own support on which the diodes are first affixed in an approximate position, after which they are repositioned for calibration purposes.

The calibration must be carried out individually for each pair of diodes, with a complicated task which requires auxiliary equipment and specialized personnel.

The object of the invention is to provide an optical transducer of the type considered, which is adapted to supply at a distance a continuous indication of all the positions taken by a movable member along its angular or linear path, without having the disadvantages of the known transducers, and which moreover is adapted to be installed on a valve or other device even by a not very skilled person, without special equipment, and which can be calibrated by a very simple operation.

According to the invention this object is attained by means of an optical transducer as claimed.

Some characteristics which are claimed are contained in Italian patent application TO 2001 A 000958 and in corresponding international patent application WO 02/097313 Al, both in the name of the same Applicants, which were published after the priority date of the present application.

As will be better understood from the description which follows, made with reference to the drawings, the main advantage of the invention consists of the fact that the rows of diodes are preinstalled in predetermined fixed positions on respective fixed supports, and it is possible to continuously detect and remotely indicate the various positions taken by the movable member, for example the various positions taken by the valve member of a valve between its complete closure and its complete opening.

The invention also relates to fluid valves of the butterfly type and of the gate type, having a movable member, a rotary shaft or a sliding stem, respectively, equipped with a transducer according to the invention.

The invention will be better understood from the reading of the detailed description which follows, made with reference to the attached drawings, given by way of non-limiting example and in which: Figure 1 is an elevational view of an optical transducer according to a first embodiment of the invention, of the angular type, associated to a movable member constituted by the rotating shaft, partially shown, of a butterfly valve or the like, Figure 2 is an exploded perspective view of the transducer of Figure 1, in which the rotating shaft is partially shown as well, Figures 3a, 3b and 3c are cross sections taken in the transverse plane indicated III- III in Figure 1, which show the transducer of Figures 1 and 2 in three different conditions of detection which correspond, respectively, to the angular positions of complete closure, half opening and complete opening of the butterfly valve member of the valve, Figure 4 is a diagram of an electric/electronic circuit used in both the rotating and linear embodiments shown, Figure 5 is a perspective of an optical transducer according to another embodiment of the invention, of the linear type for a movable member constituted by the sliding stem of a gate valve or the like, and Figures 6a, 6b and 6c are sections taken in the longitudinal plane indicated VI-VI in Figure 5, which show the transducer of Figures 4 and 5 in three various conditions of detection which correspond, respectively, to the linear positions of complete closure, half opening and complete opening of the gate valve member of the valve.

Referring to Figures 1, and 2, a movable member constituted by the rotary shaft of a butterfly valve (not shown) is indicated 10.

A transducer of the angular type according to the invention, generally indicated 12, which surrounds the shaft 10, is secured on an upper flange of the valve.

The transducer 12 comprises a pair of fixed, rigid annular discs, a lower one 14 and an upper one 16, which freely and concentrically surround the shaft 10 and are supported from an upper flange (not shown) of the valve.

The two discs 14,16 are fixed so as to be parallel to each other as well as to be parallel to an intermediate dimming plane, whose trace is indicated P in Figure 1.

The dimming plane P is normal to the axis of rotation of the shaft 10 of the valve.

A printed circuit 18 is incorporated in the lower disc 14 and carries a row of light- receiving diodes PR arranged according to an arc of a circle concentric to the axis of the shaft 10.

The light-receiving diodes PR are turned towards the upper disc 16.

In the upper disc 16 a printed circuit 20 is incorporated, which carries a row of light-emitting diodes PE arranged according to an arc of a circle as well, which is concentric to the axis of the shaft 10 and is exactly a mirror image of the row of light-receiving diodes.

Therefore, the two rows of diodes extend along respective arched paths which are parallel to each other and located on respective opposite sides of the dimming plane P.

The light-emitting diodes PE are turned towards the lower disc and each of them emits a light beam which is directed towards an homologous light-receiving diode PR. These light beams lay on an arched virtual surface S which is oriented so as to be normal to the dimming plane P.

Preferably, the light-emitting diodes PE are of the infrared light type and in any case they emit the light continuously or by impulses.

The light-emitter diode of the preferred type emits a beam of infrared light with a wavelength of 950 nanometers. Advantageously, the light beams of the light-emitting diodes PE have such an amplitude to at least illuminate at the same time at least in part two adjacent light- receiving diodes PR.

Still advantageously, in each of the two rows the light-emitting diodes P, on the one hand, and the light-receiving diodes PR, on the other hand, are arranged without any hiatus between the adjacent diodes.

Referring to Figures 1, 2,3a, 3b and 3c, in the embodiment shown, in an intermediate position between the two discs 14,16 a ring 22 is fastened on the shaft and has a radially projecting arched wing 24 of an opaque material, acting as a dimmer, which lays in the aforesaid dimming plane P.

When the dimmer 24 is interposed between the light-emitting diodes PE and the light-receiving diodes PR, it intercepts the corresponding light beams.

Referring to Figures 3a, 3b, 3c, the dimmer 22 has, in the dimming plane P, an edge 26 which extends at least in part according to a curved line which intersects the aforesaid virtual surface S in such a manner that on one side of the intersection the light-receiving diodes are masked and on the other side of the intersection the light-receiving diodes are illuminated by the light beams.

The aforesaid intersection is indicated X in Figure 3b.

As can be seen in Figures 3a, 3b and 3c, the edge 26 of the dimmer comprises a large section 28 in the form of an arc of a circle, centred on the axis of the shaft 10, and, in the location of the diode rows PR and PE, a deviated section 30 with a radius which decreases with respect to the axis of the shaft 10, for example a segment of an arc of a spiral, where the aforesaid intersection X is located.

At its end opposite to the deviated section 30, the edge 26 of the dimmer 24 terminates with a neatly radial section 32 whose function will be clarified more below.

In Figures 3a, 3b and 3c and in their description the case has been considered in which the diode rows PE, PR have an outline like an arc of a circle and the edge 26 of the dimmer has an outline which decreases with respect to the axis of the shaft 10, but these outlines could be exchanged for each other.

Before passing to a description of the operation of the transducer of Figures 1 and 2 in a closing sequence of a butterfly valve and an operation of manual calibration of the said transducer, the electric/electronic circuit diagrammatically shown in Figure 4 will be described.

Referring to Figure 4, the circuit shown is subdivided into two parts: one part, enclosed in a dash-and-dot box RP, is in a remote location, for example in a control room; another part, enclosed in a dash-and-dot box TR, is incorporated in the transducer of Figures 1 and 2.

The two parts RP and TR are electrically connected through a multiple connector, one part of which is indicated 36 in Figure 2 and is carried by the upper disc 16.

The part RP comprises a local direct current power source DC, for example of 24V, a light indicator LZ (for example a LED) to indicate the complete closure of the valve, a light indicator LF (for example a LED) to indicate the complete opening of the valve, and an alphanumeric visual display unit ND (for example a liquid crystal display) to indicate the percentage or the degrees of opening of the valve.

The visual display unit ND can be replaced or supplemented by a computer.

The part TR incorporated in the transducer 12 comprises for example a flat electronic board with printed circuits (not shown), which can be affixed to the upper disc 16 of Figures 1 and 2. This board comprises and/or carries in its turn the following electric/electronic components: a voltage regulator/reducer fed by the power source DC and which delivers a stabilized d. c. voltage, of 5V for example; a microprocessor uP fed by the regulator/reducer VR; a digital/analogue converter D/A interposed between the microprocessor uP and the visual display unit ND and which is adapted to feed an analogue signal, which varies with continuity between 4 and 20 mA, to the visual display unit ND; a group 01 of opto-insulators for digital signals, interposed between the microprocessor uP and the light indicators LZ and LF.

A light indicator LC, directly fed by the microprocessor u. P, is disposed on the upper face of the upper disc 20 of Figures 1 and 2 and is clearly visible to the installer during the calibration step of the transducer, which will be described more below.

Also electrically connected to the microprocessor tP are, among the other things, the printed circuits 18,20 (Figure 1) which carry the light-receiving diodes PR and the light-emitting diodes PE, respectively.

Referring now to Figures 3a, 3b and 3c, a closure sequence of a butterfly valve will be described.

It will be assumed that the manoeuvre for closing the valve takes place in a clockwise direction (in the Figures) and that it involves a rotation of the valve member by little more than 90°, in order to take account of a desirable angular overtravel of closure.

It will also be assumed, as shown, that each row of light-emitting diodes PE and light-receiving diodes PR comprises ten diodes arranged without any hiatus between the adjacent diodes, all being dimensioned in such a manner as to cover the aforesaid angle of little more than 90°.

The ten light-receiving diodes PR are indicated PR1, PR2, PR3, PR4, PR5, PR6, PR7, PR8, PR9 and PR10 in Figures 3a, 3b and 3c.

In the condition of Figure 3a, which corresponds to the complete closure of the valve, the nine light-receiving diodes PR1, PR2, PR3, PR4, PR5, PR6, PR7, PR8 and PR9 are fully illuminated and their row delivers a maximum analogue position signal; the radial section 32 masks by one half, at least approximately, the last light-receiving diode PR10, for the purpose which will be clarified more below.

The microprocessor u. P sends, through the converter D/A, to the visual display unit ND a signal to which a readable indication corresponds, such as for example "0°","0. 00","0%","OFF","VALVE CLOSED", etc.

In the condition of Figure 3b, which corresponds to a partial opening of the valve (to approximately 45°), the first five light-receiving diodes PR1, PR2, PR3, PR4 and PR5 are totally darkened; the three following diodes PR6, PR7 and PR8 are partially and progressively illuminated; the two last diodes PR9 and PR10 are still totally illuminated. In this condition, the row of light-receiving. diodes supplies to the microprocessor liP a position signal which corresponds to the 45°- position of the butterfly valve member, with all the"nuances" (fractions of degree) of the signal given by the partially masked diodes PR6, PR7 and PR8.

The microprocessor uP calculates these fractions and, through the converter D/A, applies to the visual display unit ND a signal such that the latter displays the corresponding indication, such as for example"50% OPEN","45°","50%"or "0. 50".

In the condition of Figure 3c, which corresponds to the total opening of the valve (a little more than 90°), all the ten light-receiving diodes PR1, PR2, PR3, PR4, PR5, PR6, PR7, PR8, PR9 and PR10 are darkened. In this condition, the row of light-receiving diodes supplies to the microprocessor uP a zero or low position signal which corresponds to the full opening of the valve.

The microprocessor uP, through the converter D/A, then applies to the visual display unit ND a signal such that the latter displays the corresponding indication, such as for example"100% OPEN","90°","100%"or"1. 00".

A specific function of the last light-emitting diode PR10 of the row will be now clarified.

The light indicator LC, which is on the upper face of the upper disc 16 (Figures 1 and 2) is clearly visible to the installer during the calibration step which will be discussed more below.

Referring back to Figures 1 and 2, the ring 22 is fastened to the shaft 10 in a loosenable manner. Preferably, as shown in Figures 1, 2,3a, 3b and 3c, the fastening is obtained by means of a setscrew 34: by loosening screw 34 with a simple wrench, the installer can rotate the ring 22, along with its dimmer 24, with respect to the shaft 10, to carry out an accurate calibration of the transducer.

The calibration is manually carried out by the installer by placing the butterfly valve member of the valve in the end-of-travel angular position of complete closure, which corresponds to the situation of Figure 3a.

In this situation the radial section 32 of the edge of the dimmer 24 is in the position of the last light-receiving diode PR10.

In the circuit of Figure 4 the microprocessor u. P is so arranged as to deliver a lighting signal to the light indicator LC which is in front of the installer who is carrying out the calibration, when the radial section 32 of the dimmer 24 is, as in Figure 3a, exactly halfway on the diode PR10 and masks the lighting of the latter by 50%. In other words, the microprocessor uP is so arranged as to deliver the aforesaid lighting signal when it receives, from the row of the ten light-receiving diodes PR, a signal equal to 95% of the signal that it would receive if all the ten light-receiving diodes were completely illuminated (which never takes place, because the last diode PR10 is never uncovered completely).

Let us assume that the light indicator LC is not lit when the installer who carries out the calibration has brought the butterfly valve member of the valve to the angular end-of-travel position of complete closure (neither the remote indicator LZ has lit, but the installer cannot see it).

After he has made sure that he actually has closed the valve to a full stop, the installer then loosens the screw 34 (Figures 1,2, 3a, 3b, 3c) and moves the dimmer 24 to and fro, that is clockwise and anticlockwise, until the radial section 32 of the edge of the dimmer exactly masks the half of the last light-receiving diode PR10 : at this very instant the indicator lights up and the installer is assured that the calibration of the closure position of the valve has been executed correctly.

After that, the installer blocks the dimmer 24 again by tightening the screw 34.

Once the screw 34 has been blocked, the operator proceeds to the calibration of the opening position of the valve.

In order to carry out this calibration, the operator opens the valve completely and connects to the connector 36 of Figure 2 a keyboard or a computer, not shown, by which he applies to the microprocessor uP of Figure 4 a calibration signal to calibrate the opening position of the valve.

The calibration is thus terminated.

Reference to Figures 5, 6a, 6b, 6c will be made to describe a linear embodiment of the optical transducer according to the invention.

In this description the light-emitting diodes are still indicated PE and the light- receiving diodes are still indicated PR (PR1, PR2, PR3, PR4, PR5, PR6, PR7, PR8, PR9, PR10 in Figures 6a, 6b, 6c).

In Figures 5 and 6a, 6b, 6c the parts analogous to those of the angular embodiment of Figures I and 2 will be indicated as far as possible by the same reference numerals increased by 100.

Referring to Figure 5, 110 indicates a movable member constituted by the sliding stem of a gate valve (not shown). A transducer of the linear type according to the invention, generally indicated 112, is secured on a upper flange of the valve and is located beside the stem 110.

The transducer 112 has an annular flange (not shown) which, in the installed condition, is bolted to the upper flange of the valve.

The annular flange supports a pair of fixed, rigid plates 114,116 facing each other, which advantageously may be in the form of flat electronic printed circuit boards.

The two plates 114, 116 are fixed in such a manner as to be parallel to each other as well as parallel to the axis of the stem 110 and to an intermediate dimming plane, analogous to the plane P of Figure 2.

On the face of the plate 116 which is turned towards the plate 114 there is affixed a linear row of light-emitting diodes PE which emit respective light beams towards the plate 114.

On the face of plate 114 which is turned towards the plate 116 there is affixed a corresponding linear row of light-receiving diodes PR (indicated PR1, PR2, PR3, PR4, PR5, PR6, PR7, PR8, PR9, PR10 in Figures 6a, 6b, 6c), which exactly face the respective light-emitting diodes PE and receive the light beams from the latter, all in a manner analogous to what has been described above in connection with the embodiment of Figures 1 and 2.

The two rows of diodes PE and PR, in addition to being rectilinear, are parallel to the direction of sliding of the stem 110, and the light beams emitted by the light- emitting diodes PE extend along virtual plane surfaces of trace S (Figures 6a, 6b, 6c), which are normal to the aforesaid dimming plane.

Also in this linear embodiment, preferably, the light-emitting diodes PE are of the infrared light type and in any case they emit the light continuously or by impulses.

Also, the preferred type of light-emitting diode emits a beam of infrared light with a wavelength of 950 nanometers.

As shown in Figure 5, each plate 114, 116 carries on its outer face a light indicator LC. The two indicators LC, which advantageously are LEDs, are electrically in parallel and have the same function as the indicator LC of Figures 1 and 2.

Still referring to Figures 5 and 6a, 6b, 6c, in an intermediate position between the two plates 118, 120 a ring 122 is fastened to the stem 110, and a wing or flag 124 of an opaque material, having the function of a dimmer, radially extends from the ring and lies in the aforesaid dimming plane between the two rows of diodes PE, PR.

The dimmer 124 has, in the aforesaid dimming plane, a longitudinal edge 126 which intersects the aforesaid virtual surface S in such a manner that on one side of the intersection the light-receiving diodes are masked and on the other side of the intersection the light-receiving diodes are illuminated by the light beams.

The aforesaid intersection is indicated X in Figure 6b. As can be seen in Figures 6a, 6b and 6c, the edge 126 of the dimmer comprises a rectilinear section 128 which is parallel to the axis of the stem 110 and, in the position of the rows of diodes PR and PE, an oblique or deviated rectilinear section 130, which upwardly extends at a decreasing distance from stem 110, and where the aforesaid intersection X is located.

At its upper end, the edge 126 of the dimmer 24 terminates with a right-angle section 132 whose function will be clarified more below.

In Figures 6a, 6b and 6c and in the corresponding description the case has been considered in which the rows of diodes PE, PR have a rectilinear outline parallel to the axis of the stem 110 and the edge 126 of the dimmer has an oblique outline, but these outlines could be exchanged with each other.

A closure sequence of a gate valve will now be described with reference to Figures 6a, 6b and 6c.

In this description reference will also be made to the electric/electronic circuit of Figure 4 which, as already said, is applicable to a linear transducer as well.

It will be assumed that the manoeuvre for opening the valve takes place with an upward travel of the stem 110 (in the Figures).

It will also be assumed, as shown, that each row of light-emitting diodes PE and light-receiving diodes PR comprises ten diodes disposed without any hiatus between the adjacent diodes, the whole being so dimensioned as to cover little more than the length of the opening and closing travel of the gate valve.

The ten light-receiving diodes PR are indicated PR1, PR2, PR3, PR4, PR5, PR6, PR7, PR8, PR9 and PR10 in Figures 6a, 6b and 6c.

In the condition of Figure 6a, which corresponds to the complete closure of the valve, the nine light-receiving diodes PR1, PR2, PR3, PR4, PR5, PR6, PR7, PR8 and PR9 are fully illuminated and their row emits a maximum analogue position signal; the right-angle section 132 masks, at least approximately, one half of the last light-receiving diode PR10, for the purpose which will be clarified more below.

The microprocessor iP of Figure 4 sends to the visual display unit ND, through the converter D/A, a signal to which a readable indication corresponds, such as for example"0","0. 00","0%","OFF","VALVE CLOSED", etc.

In the condition of Figure 6b, which corresponds to a partial opening of the valve (approximately halfway of the travel), the first five light-receiving diodes PR1, PR2, PR3, PR4 and PR5 are totally darkened; the three following diodes PR6, PR7 and PR8 are illuminated partially and progressively; the two last diodes PR9 and PR10 are still illuminated totally. In this condition, the row of light-receiving diodes supplies to the microprocessor uP a position signal which corresponds to the halfway point of the travel of the valve member of the gate valve, all the "nuances"of the signal (millimetres) being given by the partially masked diodes PR6, PR7 and PR8. The microprocessor u. P calculates these fractions and, through the converter D/A, applies to visual display unit ND a signal such that the latter displays the corresponding indication, for example"50% OPEN","50%"or "0. 50".

In the condition of Figure 6c, which corresponds to a complete opening of the valve, all the ten light-receiving diodes PR1, PR2, PR3, PR4, PR5, PR6, PR7, PR8, PR9 and PR10 are darkened. In this condition the row of light-receiving diodes supplies to the microprocessor uP a zero or low position signal which corresponds to the full opening of the valve.

The microprocessor uP, through the converter D/A, then applies to the visual display unit ND a signal such that the latter displays the corresponding indication, for example"100% OPEN","100%"or"1. 00".

A specific function of the last light-emitting diode PR10 of the row will be now clarified.

At least one of the two light indicators LC which are on the outer faces of the plates 114 and 116 (Figure 5) is clearly visible to the installer in the calibration step which will be discussed more below.

Referring back to Figure 5, the ring 122 is fastened to the stem 110 in a loosenable manner. Preferably, as shown in Figures 5,6a, 6b and 6c, the fastening is obtained by means of a setscrew 134: by loosening the screw 134 with a simple wrench, the installer can slide the ring 122, along with its dimmer 124, with respect to the stem 110 in order to carry out an accurate calibration of the transducer.

The calibration is manually carried out by the installer by placing the valve member of the gate valve in the end-of-travel position of complete closure, which corresponds to the situation of Figure 6a.

In this situation the right-angle section 132 of the edge of the dimmer 124 is in the position of the last light-receiving diode PR10.

In the circuit of Figure 4 the microprocessor piP is so arranged as to deliver a lighting signal to the light indicators LC which are in front of the installer who is carrying out the calibration, when the right-angle section 132 of the dimmer 124 is, as in Figure 6a, exactly halfway on the diode PR10 and masks the lighting of the latter by 50%. In other words, the microprocessor uP is so arranged as to deliver the aforesaid lighting signal when it receives, from the row of the ten light-receiving diodes PR, a signal equal to 95% of the signal that it would receive if all the ten light-receiving diodes were completely illuminated (which never takes place, because the last diode PR10 is never uncovered completely).

Let us assume that the light indicators LC are not lit when the installer who carries out the calibration has brought the gate valve member of the valve to the end-of- travel position of complete closure (neither the remote indicator LZ has lit, but the installer cannot see it).

After he has made sure that he actually has closed the valve to a full stop, the installer then loosens the screw 134 (Figures 5,6a, 6b, 6c) and moves the dimmer 124 up and down, until the right-angle section 132 of the edge of the dimmer exactly masks the half of the last light-receiving diode PR10 : at this very instant the indicators light up and the installer is assured that the calibration of the closure position of the valve has been executed correctly.

After that, the installer blocks the dimmer 124 again by tightening the screw 134.

Once the screw 134 has been blocked, the operator proceeds to the calibration of the opening position of the valve.

In order to carry out this calibration, the operator opens the valve completely and connects to a connector, analogous to the connector 36 of Figure 2, a keyboard or a computer, not shown, by which he applies to the microprocessor u. P of Figure 4 a calibration signal to calibrate the opening position of the valve.

The calibration is thus terminated.

An optical transducer according to the invention, be it angular or linear, given its compactness, lends itself very well to be enclosed in a liquid-proof and gas-proof housing (not shown), and this makes it particularly desirable for environments in which valves or other equipment risk to be submerged by water or other liquids, such as crude oil, for example in the hold of a ship, and which also in these conditions must be able to remotely indicate with accuracy all the positions taken by their valve member.