GB1599380A - Pneumatic regulating device - Google Patents

Description

(54) PNEUMATIC REGULATING DEVICE (71) We, OBSA SPA, an Italian joint stock Company, of 9 Via Verdi, Lomagna (Como), Italy, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to a pneumatic regulating unit particularly intended for checking a variable magnitude in an operational process. More particularly, the invention relates to a pneumatic regulator which is suitable for permitting the checking of a variable during a programmed control operation.

It is known that for checking a variable in an operational process by means of a pneumatic regulator it is frequently necessary to effect variations of pressure of the control fluid in the same direction or in the opposite direction compared with the variation of the magnitude control (respectively known as direct action or inverted action).

It is frequently required that the action of a pneumatic regulator may be varied by direct action, which means to say the output signal increases as the variable under control increases, or inverted action, that is to say the output signal increases when the variable under control decreases. Hitherto this variation has been obtained by means of manual or mechanical intervention on the regulator, or again by means of using a pneumatic inverter.

This latter method using a pneumatic inverter is the only one which lends itself to a programmed or completely automated control.

Nevertheless, as compared with the use of a pneumatic inverter for the desired variation in the action of the pneumatic regulator, there is a disadvantage which has not been overcome, and lies in the fact that at the time of inversion there is inevitably a persistent delay in reaching the exact value of the output signal, a delay which implies an unchecked period of operation during which the regulating unit may act, and very often does act, in a way which is completely opposed to the function for which it was preselected.

The problem underlying the present invention is that of providing a pneumatic regulating unit which has constructional characteristics so that the abovementioned variation from direct action to inverted action may be carried out on the basis of a predetermined programme and without incurring the drawback mentioned above.

The present invention provides a pneumatic regulating unit incorporating a pneumatic relay, characterised by the fact that it comprises two parallel nozzles which are identical and which communicate pneumatically with the said relay, two shutter plates one for each nozzle, held in a shut position of the relevant nozzle by elastically deformable units and an element supported by the said regulating unit so as to oscillate around an axis parallel to the axis of the said nozzles and acting on one or other of the said plates so as to move them away from their respective nozzles against the said elastically sprung units, the said element being angularly displaced in one direction or in the opposite direction around the said spindle by an actuator which operates on the basis of the displacement between the effective value of the process and the desired and variable value according to a predetermined programme.

The principal object of the invention lies in overcoming the necessity of providing a pneumatic inverter of the signal and the elimination of the delay in reaching the exact value of the output signal at the moment of such inversion.

One embodiment of a pneumatic regulating unit in accordance with the invention, will now be described by way of example and with reference to the accompanying drawings in which: Figure 1 shows in perspective a pneumatic regulating unit in accordance with the invention and Figures 2 and 3 show a plan view and a front elevation respectively of a constructional detail of the said unit.

With reference to the above-mentioned Figures, 1 indicates generally a pneumatic control unit (pneumatic regulator) in accordance with the invention, used for controlling a variable in operational processes. The regulating unit is conventionally equipped with a pneumatic relay having a body 2 with a rear wall 2a extended upwards to support a plate 3 essentially of the bracket type on top of the body 2 and in a predetermined position and distance from it. Adjacent the front wall of the said regulating unit 1, there is fixed to the said plate 3 by conventional removable means, for example screws 4, 5, a plateshaped support 6 essentially shaped like a bridge. This support 6 rigidly supports in its central position two nozzles 7, 8 of conventional type, which nozzles extend parallel to one another and spaced from one another, towards the said rear wall 2a.

Each of the said nozzles 7, 8, is equipped with its own union 7a, 8a, for pneumatic connection in a conventional manner with the said pneumatic relay 2.

On to the plate-shaped support 6 and at the side of the nozzles 7, 8, there are fixed two identical riders 9, 10, of U shape with wings 9a, 9b, and 10a, 10b, parallel to the axes of the said nozzles 7, 8.

Between the wings 9a, 9b of the rider 9 there is rotatably supported a spindle 11 with its axis perpendicular to the axis of the relevant nozzle 7. On the spindle 11 there is fixed centrally a square plate 12. The said spindle 11 is subjected to the resilient action of a spiral spring 13. The action of this spring is such that the arm 12a of the square plate 12 tends to close the nozzle 7. At the free end of the other arm 12b of the said square plate 12 there is fixed a threaded stem 14, perpendicular to the arm 12b carrying a stop 15 essentially of the disc type.

The spaced distance of the said disc type stop from the arm 12b is adjustable by screwing the threaded stem 14 which supports it.

In a manner which is completely analogous to that described with reference to the rider 9, the rider 10 supports a spindle 111 which is subjected to the action of a spiral spring 113 and on which there is mounted a square plate 112. The arm 112a of the said square plate is normally maintained in a shut position for the nozzle 8 by the action of the said spiral spring 113, whilst the arm 112b supports, via a threaded stem 114, a disc type stop 115.

A U-shaped element 16 with parallel wings 16a, 16b, is mounted on a support 17 of the regulating unit. The spindle around which the said element 16 may be displaced angularly in two opposite directions, in the manner described above, extends parallel to the axes of the nozzles 7, 8, in a position intermediate the said nozzles. To the front wing 16b of the element 16 there is fixed an overhanging pin 18, the free end 19 of which is spherical in shape, and positioned between the disc stops 15, 115. Angular displacements in one direction or the other of the said element 16 around its relevant spindle result in corresponding displacements of the said spherical end 19, in one direction or the other, along an arc of circle which is concentric with the said spindle.

The wing 16a of the U-shaped element 16 is subjected to the action of an actuator shown diagrammatically at 20, which functions on the basis of the displacement between the effective value of the process and the desired and variable value according to a predetermined programme On the basis of such a programme, laid down in accordance with the requirements of an operational process of which it is intended to control a variable, the nozzle 7 or the nozzle 8 opens with immediate variation in the action of the pneumatic regulator, in response to angular displacements in one direction or in the opposite direction of the element 16 around its own spindle.

WHAT WE CLAIM IS: 1. A pneumatic regulating unit incorporating a pneumatic relay, characterised by the fact that it comprises two parallel nozzles which are identical and which communicate pneumatically with the said relay, two shutter plates one for each nozzle, held in a shut position of the relevant nozzle by elastically deformable units and an element supported by the said regulating unit so as to oscillate around an axis parallel to the axes of the said nozzles and acting on one or other of the said plates so as to move them away from their respective nozzles against the said elastically sprung units, the said element being angularly displaced in one direction or in the opposite direction around the said spindle by an actuator which operates on the basis of the displacement between the effective value of the process and the desired and variable value according to a predetermined programme 2. A pneumatic regulating unit substantially as hereinbefore described by way of example and with reference to the accompanying drawings.

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

Claims (2)

**WARNING** start of CLMS field may overlap end of DESC **. a variable in operational processes. The regulating unit is conventionally equipped with a pneumatic relay having a body 2 with a rear wall 2a extended upwards to support a plate 3 essentially of the bracket type on top of the body 2 and in a predetermined position and distance from it. Adjacent the front wall of the said regulating unit 1, there is fixed to the said plate 3 by conventional removable means, for example screws 4, 5, a plateshaped support 6 essentially shaped like a bridge. This support 6 rigidly supports in its central position two nozzles 7, 8 of conventional type, which nozzles extend parallel to one another and spaced from one another, towards the said rear wall 2a. Each of the said nozzles 7, 8, is equipped with its own union 7a, 8a, for pneumatic connection in a conventional manner with the said pneumatic relay 2. On to the plate-shaped support 6 and at the side of the nozzles 7, 8, there are fixed two identical riders 9, 10, of U shape with wings 9a, 9b, and 10a, 10b, parallel to the axes of the said nozzles 7, 8. Between the wings 9a, 9b of the rider 9 there is rotatably supported a spindle 11 with its axis perpendicular to the axis of the relevant nozzle 7. On the spindle 11 there is fixed centrally a square plate 12. The said spindle 11 is subjected to the resilient action of a spiral spring 13. The action of this spring is such that the arm 12a of the square plate 12 tends to close the nozzle 7. At the free end of the other arm 12b of the said square plate 12 there is fixed a threaded stem 14, perpendicular to the arm 12b carrying a stop 15 essentially of the disc type. The spaced distance of the said disc type stop from the arm 12b is adjustable by screwing the threaded stem 14 which supports it. In a manner which is completely analogous to that described with reference to the rider 9, the rider 10 supports a spindle 111 which is subjected to the action of a spiral spring 113 and on which there is mounted a square plate 112. The arm 112a of the said square plate is normally maintained in a shut position for the nozzle 8 by the action of the said spiral spring 113, whilst the arm 112b supports, via a threaded stem 114, a disc type stop 115. A U-shaped element 16 with parallel wings 16a, 16b, is mounted on a support 17 of the regulating unit. The spindle around which the said element 16 may be displaced angularly in two opposite directions, in the manner described above, extends parallel to the axes of the nozzles 7, 8, in a position intermediate the said nozzles. To the front wing 16b of the element 16 there is fixed an overhanging pin 18, the free end 19 of which is spherical in shape, and positioned between the disc stops 15, 115. Angular displacements in one direction or the other of the said element 16 around its relevant spindle result in corresponding displacements of the said spherical end 19, in one direction or the other, along an arc of circle which is concentric with the said spindle. The wing 16a of the U-shaped element 16 is subjected to the action of an actuator shown diagrammatically at 20, which functions on the basis of the displacement between the effective value of the process and the desired and variable value according to a predetermined programme On the basis of such a programme, laid down in accordance with the requirements of an operational process of which it is intended to control a variable, the nozzle 7 or the nozzle 8 opens with immediate variation in the action of the pneumatic regulator, in response to angular displacements in one direction or in the opposite direction of the element 16 around its own spindle. WHAT WE CLAIM IS:

1. A pneumatic regulating unit incorporating a pneumatic relay, characterised by the fact that it comprises two parallel nozzles which are identical and which communicate pneumatically with the said relay, two shutter plates one for each nozzle, held in a shut position of the relevant nozzle by elastically deformable units and an element supported by the said regulating unit so as to oscillate around an axis parallel to the axes of the said nozzles and acting on one or other of the said plates so as to move them away from their respective nozzles against the said elastically sprung units, the said element being angularly displaced in one direction or in the opposite direction around the said spindle by an actuator which operates on the basis of the displacement between the effective value of the process and the desired and variable value according to a predetermined programme

2. A pneumatic regulating unit substantially as hereinbefore described by way of example and with reference to the accompanying drawings.