DE1523496A1 - Electropneumatic converter - Google Patents

Description

The invention relates to an electropneumatic device Converter. The invention particularly relates to electropneumatics Converter for use in electrical control loops in which the last control element is pneumatic is operated.

The invention is based on the object of creating an improved electropneumatic converter that is simple can be attached to a control valve or a similar pneumatically operated control element. Such a The transducer is fed with a direct current on the order of milliamps and generates a pneumatic pressure, which is directly proportional to the supply current.

The invention is characterized by a housing in which a switching motor assembly is located, the one

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Permanent magnets and pole pieces associated therewith, by an armature and a coil arrangement which has an electrical Has coil-carrying bracket and rotatably supports an armature which is between the pole pieces as a function is movable by the excitation of the coils, through an outlet nozzle arranged on the housing and functionally connected to the armature, wherein the armature is biased towards the outlet nozzle to limit the amount of air escaping from the nozzle is, through a return part, which efficaciously with the armature and acts on the armature to increase the amount of air discharged from the discharge nozzle and by means for feeding a direct current signal into the coils their excitation and generation of a magnetic field with a strength proportional to the DC signal changes, the magnetic attraction between the armature and the pole pieces causing the armature to move, to change the position of the armature in relation to the nozzle opening to control the amount of air discharged from the nozzle, and wherein the return member is in a force balance relationship with the nozzle cooperates.

The electro-pneumatic converter according to the invention contains a switching motor and a relay which is connected directly to a common housing. The switch gate includes an adjustable coil and device to adjust the anchor. The shift motor of the

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electropneumatic converter according to the invention is bo designed and arranged that it interchangeably accommodate several Rüokführungsbälge (one for each exit area) can. The shift motor used in the invention is also provided with a relatively simple temperature compensation device Mistake. The converter according to the invention has a high loop gain, a high output torque and a torsion bar tension, which together result in a high static effect of the transducer.

The invention is to be explained in more detail below with reference to the drawing.

Pig. 1 is a perspective view of a

electropneumatic converter designed according to the invention and on a Control valve is attached,

Fig. 2 is a plan view of the electropneumatic Converter, with the cover of the housing removed, to the shift motor assembly to show,

Fig. 3 is a section through the electropneumatic

Converter and shows the switch motor and relay,

4 is an end view of the shift motor assembly;

Figure 5 is a section 5-5 of the torsion motor assembly according to Fig. 6,

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Pig. 6 is a section 6-6 through the Schaltino door arrangement according to Fig. 5 »

7 is a perspective view of the armature and the coil holder;

Fig. 8 is a rear view of the transducer housing and relay;

Fig. 9 is a view 9-9 through Figs shows the connection of the relay with the housing for the converter, and

Fig. 10 is a schematic representation of the transducer of the invention.

In Fig. 1, an electropneumatic converter 10 is shown, which is designed according to the teaching of the invention and has a housing 11 which is fastened on a support 12 which is attached to the housing of a control valve 14 is appropriate to regulate it. The electropneumatic converter 10 can also be on a standpipe by means of a submarine connection.

If desired, an air set 16 and a pressure gauge 18 can also be attached to the electropneumatic converter 10 be.

The pneumatic output signal from the transducer 10 is the actuator of the control valve 14 or another device to be controlled pneumatically via a

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Line 20 supplied. The actuator for the control valve can contain a membrane or a piston.

From the Pig. 2 and 3 it can be seen that the converter is essentially a shift motor 22 within the housing 11 contains, which is formed from a tub 24 and a cover 26 which is screwed onto the tub 24. aside from that there is a relay 28 in the housing 11, which is directly connected to the tub 24 without additional pipelines would be required. The converter 10 is used in electrical control loops in which the am The end of the control element is pneumatically operated. The converter comes with a DC input signal in the Of the order of milliamps and generates a pneumatic output pressure that is directly proportional to the Input signal is.

The shift motor 22 sets the first stage in the conversion path from the electrical input signal to the The second stage in the conversion path is formed by the relay 28.

The switching motor essentially consists of a nozzle flap amplifier and the associated electromechanical Elements. Like from the Pig. 2 to 6 can be seen, the switching motor 22 has an upper pole arrangement with an upper one Pole plate 30 and upper pole pieces 31, as well as a permanent magnet 32 and a lower pole arrangement with a lower pole plate 34 and pole pieces 35. The arrangement,

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consisting of the upper pole plate 30, the pole pieces 31 and 35 and the permanent magnet 32 and the lower pole plate 34, is secured by appropriate fastening devices which are formed from four round screws 36 in the illustrated embodiment.

The lower pole plate 34 is firmly attached to the tub 24 by machine screws 38 (Pig. 2) so as to Shift motor 22 to keep within the tub 24.

The switching motor 22 has a holder 42 for electrical coils 44 and 45 and for an armature 46 which is rotatable is stored within the housing. One end 46a of the armature 46 cooperates with an opening 50a of a nozzle 50, which is inserted into a conical opening in the lower pole plate 34. The end 46a more or less covers the opening 50a and thereby controls the amount of air flowing out.

The armature 46 rotates about a centrally located pivot pin 52 when the input signal changes and covers so more or less the nozzle 50. The direction of the current flow through the coils 44 and 45 determines the direction of rotation of the armature 46. Interchanging the feed lines of the coils therefore leads to the opposite effect. Of the Armature and the pole pieces are preferably made of magnetic material that has low hysteresis losses and has good magnetic properties.

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A stop 62 (Fig. 3) at the end 46a of the armature 46 is adjustable in its distance from the armature so that it is ensured that the opening 50a of the nozzle is covered by the armature 46 mounted between the pole pieces and the air flow is restricted in the desired manner. The exterior of the peg-shaped portion of the stop 62 is threaded into a threaded bore in end 46a of the armature. A lock nut 63 holds the stop 62 in the adjusted position.

To bias the end 46a of the armature in the direction of the nozzle, i.e. in the closing direction, a spring 66 is provided, which acts between the armature 46 and a contact part 68 into which an adjusting screw 70 is screwed, with the help of which the preload on the anchor can be adjusted. A pin 71 of the adjusting screw 70 is used for adjustment, which is rotatably mounted in the pole plate 30, outer threads which engage in a threaded hole in the contact part 68. The adjustment by changing the preload of the spring 66 is referred to as the zero adjustment. The zero setting is used to set the initial outlet pressure for a desired value of the input signal.

In addition, return means 75 are provided which move the armature 46 back against the bias of the spring 66. The return means 75 include return bellows 76 which have their ends on a base 77 and on a Attack cap 78. The return means 75 are exchangeable

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between one end 46b of the armature and the upper pole plate 30 attached; the replacement of the return means 75 is very easy. This is therefore necessary in order to achieve various To be able to use return bellows for different exit areas.

The return means 75 can be replaced very easily by first loosening the nut 79, which holds a pin 80 on the end of the base 77 which protrudes through an opening in the armature 46. After removing a fastening screw 82 which extends through an opening in the upper pole plate 30 and is screwed into the cap 78, the return means can be pulled out of their position with the bellows. From Fig. 5 it can be seen that the end 46b of the armature 46 is provided with a slot 46c through which it is possible to easily move the pin 80 laterally pull out the anchor. A seal 84 is provided between the upper pole plate 30 and the cap 78, which seals the Is intended to prevent recirculation air from flowing out of the bellows arrangement.

Another essential feature of the invention is the use of an adjustment of the range whereby a Means is provided to achieve a full change in the output pressure with a full change in the input signal. To adjust the range, a rod 90 made of magnetic material (FIGS. 5 and 6) is moved towards the magnet 32 or moved away from it, so a more or less large one

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to create magnetic shunt for the working air gap. The result is a change in the torque generated. The rod 90 made of magnetizable material is on one end of the pole plate 34 held by a spring support 91, which at one end of the rod 90 by screws 92 and is also attached to the pole plate 34 by screws 93. The spring support 91 is compliant and acts normally so that it biases the upper end of the rod 90 towards the permanent magnet 32. An adjusting screw 94, which rests with its end on the pole piece 31, can be rotated so as to the position of the rod 90 with respect to to adjust the permanent magnet 32. In the set position, the screw 94 is "locked" by a lock nut 96 tightened.

The bracket 42 for the armature 46 and the coils 44 and 45 (Fig. 7) have a pair of plates 54 and 56, the are interconnected by the ends of the pivot pin 52. Each plate has an inwardly extending one Arm 54a and 56a provided, in which there are elongated recesses 54b and 56b are located. In addition, the plates 54 and 56 have downwardly directed legs 54c and 56c. In each of the holes 54c and 56c are elongated holes 54d and 56d. The elongated holes 54d and 56d serve to adjust the position of the holder 42 in relation to the lower pole plate 34 and thus to adjust the position of the armature 46 between the

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Pole pieces, 31 and 35, as will be explained in more detail below.

As can best be seen from FIGS. 4 and 5, two identical coils 44 and 45 are on the holder 42 by means of Screws 102 fastened. The armature 46 is inserted through the two coils 44 and 45 and with the bracket connected by screws 60, which preferably have hexagonal heads.

The bracket 42 is adjustable because of the elongated holes 54d and 56d in the plates 54 and 56. The bracket 42 is attached to the lower pole plate 34 by means of screws 104, which preferably have hexagonal heads. Before the four screws 104 are tightened, the armature 46 is centered between the two pole pieces 31 and 35. This setting will made possible by the elongated holes 54d and 56d in the plates 54 and 56.

4, 5 and 6 it can be seen that a terminal block 105 is attached directly to the shift motor. the Terminal block consists of a connection strip 106 and a holder 107, which is made of a material whose temperature curve runs in the opposite sense as the the pole pieces 31 and 35 and the armature 46. The bracket 107 is attached to the pole plates 30 and 34 by screws 107a. The holder 107 is arranged with respect to the permanent magnet 32 in such a way that a part of the of the permanent magnet generated magnetic flux through the

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Bracket flows. Such an arrangement of the individual parts temperature compensation is achieved through terminal block 105.

From the Pig. 3, 8 and 9 it follows that the relay is connected directly by screws 25, which are preferably clamping screws are attached to the tub 24 without the need for piping. An inlet port 108 in tub 24, which is connected to a suitable source of compressed air, is in communication with a chamber 109, which see between the Trough 24 and the housing of the relay 28 is located. The chamber 109 is sealed by a seal 110 which is between the tub 24 and a housing part 112 of the relay 28 is located.

From the interior of the housing 11, which is formed by the cover 26 and the tub 24, air flows through a Outlet opening 114 in the tub 24, which directly with a Outlet port 116 in relay 28 via passage 118 in Connection. A seal 119 extends around the channel 118 between the trough 24 and the relay 28 and which prevents the escape of air from the channel 118. In the same way, an opening 120 in the relay 28 communicates directly with a channel 122 in the tub 24, which is connected to the nozzle 50. A seal 124 runs around the opening 120, which has an undesirable effect Avoids pressure loss.

It should be noted that in the air ducts between the tray 24 and the relay 28 air locks 126 and 128 from

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porous stainless steel are arranged. The usage this flame barriers in connection with the encapsulation the housing results in an explosion-proof housing. One filter

129 lies in the outlet opening 116 and prevents penetration dirt in the relay 28.

Looking at the construction of the relay 28, it can be seen that the relay housing is made up of separate parts 112,

130 and 132, which are interconnected and attached to the tub 24 are connected. Inside the relay 28 are a pair of diaphragms 134 and 136 attached to their periphery are attached to the relay housing so that their central parts are longitudinally within the housing of the Relay 28 can move. A ring 140 is fixedly attached to the diaphragms 134 and 136 and moves with them this. The diaphragm together with the relay housing form chambers 141, 142 and 143.

Two cooperating valves, namely an inlet valve 150 and an outlet valve 152, are within the Relays 28 are provided and control the flow of air through the relay. The inlet valve 150 is in the closed position a spring 151 biased between the valve 15O and a plate 149 is inserted, which is fixed in the chamber 109. A spring 153 pushes the ring 140 off the Exhaust valve 152 away to let air out of chamber 141 through the exhaust passage and through ring 140, like that will be explained in more detail later.

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Compressed air from a suitable source of compressed air flows through inlet port 108 into chamber 109, which is between the relay 28 and / Öer tub 24 is located. From the Chamber 109, the air flows through a fixed constriction 144 and through a channel 145 to the chamber 143 so that the ring is pressurized against the tension of the peder 153 will. Part of the air flows from the constriction 144 through the opening 120 and channel 122 to the nozzle 50 and from there. The sealing ring, not designated, on the end of a pin 144 in which the constriction is located, seals the chamber 109 opposite the opening 120.

If the nozzle opening is covered by the stop 62 on the armature 46, then builds up inside the chamber 143 keep pressing until it is big enough to handle the To overcome leather preload and move the inlet valve 150 away from an opening 150a so that air can flow through a Port 160 flows and the valve or other pneumatically operated device is controlled. The one through the opening 160 flowing outlet pressure continues to increase until the relay diaphragms 134 and 136 and the ring 140 by the pressure, which acts on the smaller membrane 134, in its original Position are pushed back and the inlet valve 150 is closed. The force from the pressure within the chamber 141 and the pressure acting on the diaphragm 134 is combined with the force of the spring 153, sufficient to increase the force overcome that by the inside of the chamber 143

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results in the pressure acting on the diaphragm 136, so the ring 140 moves away from the outlet valve 152, whereby air from the chamber 141 through the outlet opening in the ring HO, the chamber 142 and the outlet opening 116 can flow out. It should also be noted that air can flow out of the housing 11 through the outlet opening 114, which is connected to the outlet opening 116 in the relay 28 via channel 118.

A channel 162 allows air to flow from the chamber 109 through chamber 142 to the atmosphere at a constant rate. This enables a small clearance between the outlet valve 152 and the outlet valve seat (formed by the extension of the ring HO), whereby a dead gear is avoided.

V / andlers see the puncture method of the electropneumati according to the invention can best be based on the Pig. 10 explain. The converter 10, which is essentially the shift motor 22 and the relay 28 is used in an electrical control loop in which the last control element is pneumatic is actuated. The transducer is fed with a direct current of the order of milliamps and generates a pneumatic one Output pressure that is directly proportional to this input signal. The switching motor 22 represents the first stage in the conversion of the electrical input signal into a pneumatic one The second step in converting the electrical input signal into the pneumatic output pressure takes place in relay 28.

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Assuming that the converter is operated directly, thus an increase in the DC input to coils 44 and 45 will result in an increase in the magnetic field the spools. This increase in the magnetic field increases the magnetic flux in the armature 46 and the magnetic flux Attraction across the air gap between the armature and yokes 29 and 33. The yokes are already through the permanent magnet 32 polarized. In this case, the armature polarity may be that shown in FIG. 10, with the upper yoke 29 den North Pole and the lower yoke 33 forms the South Pole. The magnetic attraction is therefore at the nozzle-side end 46a of the Armature 46 down and on the return bellows sides End 46b directed upward, resulting in a torque that rotates armature 46 about fixed pivot pin 52, thereby covering the nozzle opening 50a.

The resulting reduction in the opening 50a of the nozzle 50 causes a pressure increase in the nozzle, in the chamber of the relay and in the return bellows 75. The return bellows 75 at-shen with nozzle 50 and channel 145 in the relay 28 via lines. 41 in connection. The relay 28 follows the increase in the nozzle pressure and increases the output pressure for the control valve. The increased pressure earth return bellows 75 creates a force which ^{acts on the armature ... 1} 46 and brings it back into its rest position. In this way, the new nozzle pressure is compared with the input flow by means of a force equilibrium.

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The nozzle pressure acts on the diaphragm 136 of the relay and pushes the ring HO, which is located between the two diaphragms 134 and 136, down against the outlet valve 152, closes the outlet port and opens the inlet port 15Oa. New compressed air then flows through inlet port 150a and port 160 from chamber 141 through line 170 to the control valve. The outlet pressure continues to rise until the heating membranes are pushed back into their original position by the force of the pressure acting on the diaphragm 134 and that Outlet valve 152 is closed again.

If the DC input signal drops, the magnetic attraction across the air gap is reduced. The anchor 46 rotates about pivot pin 52 and further exposes nozzle opening 50a, reducing the pressure in nozzle 50, in the Relay 28 and in the feedback bellows 75 drops. The diaphragm assembly moves up like that from Fig. 10 results, and the outlet port in the ring 140 is opened to bring the outlet pressure to atmospheric through lower chamber 142 and outlet port 116. The outlet pressure drops until the diaphragm assembly returns to their original position is moved back and the outlet opening is closed again. The reduced pressure in the return bellows 75 weakens the force, whereby the armature 46 returns to its rest position.

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Reversed converters work in the same way, with the difference that when the DC voltage signal arebeigt, the output pressure from the relay decreases. Vice versa a decreasing input signal increases the output pressure. The inventive improved, electro-pneumatic Converter thus contains a switching motor, which is the first stage in converting the electrical input signal into a represents the pneumatic output pressure, as well as a relay, which represents the second stage in the conversion of the electrical input signal into the pneumatic output pressure. The two-stage Training, with each level having its own control loop, enables a uniformly high level of stability for any Output loads. A feedback loop formed over all has been avoided in the present invention because to achieve a stability that is completely independent of the initial load. With a currently preferred one Embodiment of the invention, the high capacity relay amplifies the nozzle pressure of the shift motor to the output pressure in a ratio of 3: 1. For a nozzle pressure change of 4 psi, the output pressure of the relay changes by 12 psi, this covers a standard range of 3 to 15 psi.

The high loop gain, the high torque and the three-phase stress of the armature lead to a high static Quality.

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The rear of the trough of the converter housing is designed so that the relay can be easily plugged in and so, "easily accessible at any time for maintenance without that the electrical or pneumatic connections need to be destroyed. The tub and the lid are together hermetically screwed to form an explosion-proof housing, with flame arresters made of porous, stainless steel are provided in the air ducts between the housing and the relay.

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Claims (11)

Claims 1. Electropneumatic converter, characterized by a housing in which there is a switching rotor assembly, which has a permanent magnet and pole pieces associated therewith, by an armature and a coil assembly, which has an electrical coil-carrying bracket and which rotatably supports an armature between the Pole pieces is movable in dependence on the excitation of the coils, through an outlet nozzle which is arranged on the housing and is operatively connected to the armature, the armature being biased in the direction of the outlet nozzle to limit the amount of air escaping from the nozzle, by a return part which is connected to the armature Operates and acts on the armature to increase the amount of air discharged from the discharge nozzle and by means for feeding a direct current signal to the coils to excite them and to generate a magnetic field having a strength which varies in proportion to the direct current signal , where the magnetic num The movement between the armature and the pole pieces causes the armature to move to change the position of the armature with respect to the nozzle opening to control the amount of air discharged from the nozzle, and wherein the return member cooperates with the nozzle in a force balance relationship. 909834/0551 - A 2 - 2. Converter according to claim 1, characterized in that the return part has a bellows which is exchangeable for the purpose of changing the output range. 3. Converter according to claim 1, characterized in that the armature is provided with an adjustable stop for covering the nozzle so that the air flow from the nozzle is adjustable when the armature is between the pole pieces. 4. Converter according to claim 1, characterized in that within the housing a holder for a connection strip is attached to the Schaltmotorüranordnung so that the holder forms a shunt for the permanent magnet, the holder consists of a magnetizable material whose permeability is with the Temperature changes in the opposite sense as the permeability of the pole pieces and the armature, so that the temperature variation of the permeability is compensated. 5. Converter according to claim 1, characterized in that a magnetic shunt for the permanent magnet from a piece of raagnetisbaren material is adjustably attached to the permanent magnet, so that the magnetic flux in the air gap between the armature and the pole pieces can be changed. 6. Converter according to claim 1, characterized in that the holder is adjustably attached to facilitate the centering of the armature between the pole pieces in the housing. 909834/0551 - Λ 3 - 7. Converter according to claim 1 and 2, characterized in that the nozzle is connected via a line to a pneumatic relay, and that the bellows of the return part is connected to the line. 8. A converter according to claim .1, characterized in that the holder for the coils has a pair of substantially parallel plates with inwardly bent flags for holding the coil. 9. Transducer according to claim 8, characterized in that the plates are connected to one another by a pivot pin which is inserted with its ends in the plates, the armature being fastened to the rod in the center of this. 10. Converter according to claim 9, characterized in that the plates for centering the armature between the pole pieces are adjustably held in the housing. 11. Converter according to claim 7, characterized in that the housing is provided with an outlet opening and an inlet opening for compressed air and a nozzle connection opening in a wall, that the pneumatic relay has an encapsulation with an outlet opening which is complementary to the ■ outlet opening in the Housing is that a feed air inlet 909834/0551 -A4- cooperates with the feed opening in the housing, and that an outlet opening is provided which communicates with the nozzle connection opening is in connection that a sealing ring is placed around the respective complementary interlocking openings is, and that means are provided for connecting the relay to the housing, whereby special lines between the housing and the relay are omitted. SL / Sch 90983A / 0551 -Z- Blank page