US3888389A

US3888389A - Flow controller for flowing products, more particularly, bulk materials

Info

Publication number: US3888389A
Application number: US388783A
Authority: US
Inventors: Hans Oetiker
Original assignee: Buehler AG
Current assignee: Buehler AG
Priority date: 1972-08-23
Filing date: 1973-08-16
Publication date: 1975-06-10
Anticipated expiration: 1992-06-10
Also published as: JPS5317419B2; ES418109A1; CA994727A; IT991324B; SE386291B; NL7309880A; DE2342668C2; FR2197479A5; DE2342668A1; JPS4965860A

Abstract

The flow controller has a closure member of adjustable throughflow cross-section arranged on a storage bin or a gravity discharge pipe, and a regulating drive for regulating the through-flow cross-section. An inclined impact plate is secured on a first lever arm of a balance beam, in downwardly spaced relation to the closure member, so that the impact force on the plate, due to deflection thereby of the product falling through a given distance, is proportional to the actual value of the flow rate as expressed as quantity by weight per unit of time. The balance beam is pivotally connected intermediate its ends to a fixed frame and has at least one counter weight on a second lever arm, and an ajustable force-producing device acts on the balance beam in opposition to the impact force to regulate the throughflow cross-section. The deviation between the desired and actual values of the flow rate of the product, resulting from the interaction between the impact force and the force-producing device, is converted into a corresponding positive or negative pressure signal serving as a regulating signal for the regulating drive. An auxiliary beam is pivotally connected separately to the fixed frame, and the adjustable force-producing device loads the auxiliary beam. A supporting edge is mounted on the auxiliary beam for adjustment longitudinally thereof in engagement with the second lever arm of the balance beam to transmit to the latter a precisely balanced proportion of the load produced by the adjustable force-producing means, indicative of the desired value of flow rate of the product, and acting in opposition to the impact force. The adjustable force-producing device may comprise a weight movable longitudinally of the auxiliary beam in cooperation with a percentage scale, or a pressure responsive diaphragm element acting on the auxiliary beam through a lever arm extending therefrom, and the diaphragm element may be adjustable longitudinally of the auxiliary beam. Several such flow controllers may be individually adjustable with respect to different products and controlled from a central station.

Description

United States Patent 1 Oetiker 1 1 FLOW CONTROLLER FOR FLOWING PRODUCTS, MORE PARTICULARLY, BULK MATERIALS [75] Inventor: Hans Oetil-ter, St. Gallen,

Switzerland [73] Assignee: Gebruder Buhler AG, Switzerland [22] Filed: Aug. 16, 1973 [21] Appl. No.: 388,783

[30] Foreign Application Priority Data Aug. 23, 1972 Switzerland 12498/72 Apr. 27, 1973 Switzerland 6092/73 [52] U.S. Cl 222/23; 222/55 [51] Int. Cl. GOld 11/08 [58] Field of Search 222/55, 56,23; 177/251, 177/261; 198/37, 39

[56] References Cited UNITED STATES PATENTS 932,944 8/1909 Baker 222/55 1,558,668 10/1925 Carter 222/55 2,047,203 7/1936 Hensonm. 222/55 X 2,872,073 2/1959 Harper... 222/55 3,187,944 6/1965 Stock........... 222/55 X 3,308,898 3/1967 Allen et a1. 222/55 X 3,468,457 9/1969 Martin 222/55 FOREIGN PATENTS OR APPLICATIONS 747,928 4/1956 United Kingdom 222/55 [5 7] ABSTRACT The flow controller has a closure member of adjustable through-flow cross-section arranged on a storage 1 June 10, 1975 bin or a gravity discharge pipe, and a regulating drive for regulating the through-flow cross-section. An inclined impact plate is secured on a first lever arm of a balance beam, in downwardly spaced relation to the closure member, so that the impact force on the plate, due to deflection thereby of the product falling through a given distance, is proportional to the actual value of the flow rate as expressed as quantity by weight per unit of time. The balance beam is pivotally connected intermediate its ends to a fixed frame and has at least one counter weight on a second lever arm, and an ajustable force-producing device acts on the balance beam in opposition to the impact force to regulate the through-flow cross-section. The deviation between the desired and actual values of the flow rate of the product, resulting from the interaction between the impact force and the force-producing device, is converted into a corresponding positive or negative pressure signal serving as a regulating signal for the regulating drive. An auxiliary beam is pivotally connected separately to the fixed frame, and the adjustable force-producing device loads the auxiliary beam. A supporting edge is mounted on the auxiliary beam for adjustment longitudinally thereof in engagement with the second lever arm of the balance beam to transmit to the latter a precisely balanced proportion of the load produced by the adjustable forceproducing means, indicative of the desired value of flow rate of the product, and acting in opposition to the impact force. The adjustable force-producing device may comprise a weight movable longitudinally of the auxiliary beam in cooperation with a percentage scale, or a pressure responsive diaphragm element acting on the auxiliary beam through a lever arm extending therefrom, and the diaphragm element may be adjustable longitudinally of the auxiliary beam. Several such flow controllers may be individually adjustable with respect to different products and controlled from a central station.

PATENTEUJUN 10 ms Fig. 6

SHEET FLOW CONTROLLER FOR FLOWING PRODUCTS, MORE PARTICULARLY, BULK MATERIALS FIELD AND BACKGROUND OF THE INVENTION The invention relates to a flow or quantity controller for substances that can flow herein generally referred to as flowable product, particularly but not exclusively for bulk materials.

Such flow controllers commonly have a closure device of adjustable throughflow cross-section for the product arranged at a storage bin or silo, or a down pipe of some other installation. and an inclined impact plate disposed at a distance below the closure device. The impact plate is secured on a balance beam and receives the impact force or momentum due to deflection of the product falling a specific constant distance. The impact force is indicative of the outflow quantity of product per unit of time. The balance beam is pivotably connected to a fixed frame and supports a counterweight on its lever arm remote from the impact plate. The desired value of the outflow quantity can be set and compared with the actual value as indicated by the impact force. The result of the comparison is then utilized to adjust the closure device by way of a regulating drive to regulate the flow.

In order to make the discharge of product from storage compartments or processing machines in precisely regulated quantities continuous and rational, various forms of mechanical lever or spring balances for carrying out that comparison have been used.

A deviation from the position of equilibrium is detected either mechanically directly or by conversion into a proportional pressure or voltage signal, sometimes by a combined use thereof, with the correct preceding sign, and fed as a regulating signal to the regulating drive.

The energy necessary for operating the latter is usually in the same form as that used for transmitting signals. The controller can operate continuously (analog type) or noncontinuously (digital type, switching controller).

In view of the present tendency towards automation of production and distribution, it is becoming increasingly more desirable that such a controller should be able to deal with the discharge of a product with the same precision over its entire output range. In the case of parallel operation, it should also be capable of operating with exactly the same precision as others of the same type.

In the known apparatus, the force of a sliding weight or a spring, opposing the impact force on the impact plate, acts directly, in accordance with the setting thereof, as set on a weight scale, on the corresponding lever arm of the balance beam. Thus, the desired value setting of the product outflow is valid for a specific weight quantity per unit of time, to which there corresponds a volume flow which is variable in the opposite sense to the bulk weight of the product. It will be clear that the control precision decreases as the throughput decreases.

With parallel operation of several apparatuses of the known type, as a mixing battery for various products, the weight quantities supplied, for an identical desired value setting, are not identical due to tolerance variations resulting from manufacture.

SUMMARY OF THE INVENTION The objective of the present invention is to provide an apparatus of the mentioned kind and which is capable of a precisely regulatable and, if necessary, remotecontrollable, discharge of a product adapted rapidly to particular output requirements.

In accordance with the invention, the apparatus, which is based on the lever principle, attains this objective by including an auxiliary beam pivotally connected to the fixed frame of the apparatus separately from the balance beam. This auxiliary beam is loaded by a regulatable force-producing device, and a longitudinally adjustable supporting edge is secured to the auxiliary beam for precisely balanced transmission of the load, emanating from the regulatable force-producing device, to the balance beam.

Simple constructional features, such as the arrangement of the regulatable force-producing device for displacement along a percentage scale on the auxiliary beam, and the possibility of balancing the load, ema nating from the regulatable force-producing device, by means of the supporting edge which is adjustable longitudinally of the auxiliary beam, make it possible to attain increased control precision as well as independence from tolerance fluctuations. The supporting edge can be arranged in the plane including the pivots of the balance beam and the auxiliary beam. Such an arrangement makes it possible to have only a small amount of rolling friction during the movement of the supporting edge on the balance beam, as well as hysteresis-free operation of the apparatus.

To provide increased reliability and control precision, it is desirable to have linearization of the functions. With a specific product outflow, there can be allowed only small amplitudes for the mutual deflection of the balance beam and the auxiliary beam from the position of equilibrium. For this purpose, the invention includes a control nozzle which is connected to a source of pressure medium and, through a pressure conduit, to the regulating drive, and which nozzle is directed in the direction of movement of the balance beam on the fixed frame. The nozzle cross-section, starting from the nozzle entrance, initially merges into a throttle element which is followed by an abrupt widening of the cross-section, after which the nozzle crosssection does not substantially decrease up to the nozzle discharge mouth. The nozzle has associated therewith a connection for the pressure conduit leading to the regulating drive and which connection is very close to the cross-section widening, preferably immediately thereafter.

In addition to the fact that the balance beam is to fluctuate with only slight amounts of deflection with a fixedly set throughput, for linearity, it is also necessary that the lines of action of the forces acting at the balance beam should not be displaced even with load changes, so that the lever arm lengths remain constant, and also that the impact force resulting from the impact on the impact plate should be proportional to these load changes. Furthermore, to avoid falsifying the actual throughput quantity, it is absolutely necessary to control the friction occurring in the impact process.

In known apparatus of this kind, the measures for assuring non-displaceable lines of action and a proportional behavior of forces, and for controlling the friction at impact of the product on the impact plate, either cannot be determined or can be determined only to a modest extent, so that their precision leaves much to be desired.

In a likewise known apparatus, which is based on the spring balance principle, more particularly, the precision is, in fact, not influenced by the moving line of action of the impact force, but the proportionality of the spring force is adversely effected by the preload at load adjustment. More especially, here again there are no measures for meeting the other aforesaid conditions for control precision.

It is also expedient to provide a safety function for disturbances in operation.

In an advantageous development of the invention, local constancy of the lines of action and proportionality of forces can be attained, with the friction at impact reduced to a minimum, if the regulating drive comprises a cylinder-diaphragm system of considerable volume acting without friction and loaded by an opposing force, the closure device having a rotationally symmetrical geometry with axes directed in the direction of the balance beam, and the impact plate having a variable inclination and a surface quality which has an advantageous effect on friction conditions. An emergency closing device, connected between the control nozzle and the regulating driive, can provide the safety function.

The choice of a force-producing device with remote operation permits discharge of the product by remote control from a central control desk, and with a degree of automation which varies in accordance with the kind of force-producing device. For this purpose, control devices, each consisting of a pressure medium operated proportional controller which is operatively connected at the output side by its own control line to the forceproducing device of the associated flow controller, and respective desired value setting devices controlling the proportional controller, with a force-producing device for converting the given variable pressure into a force and with elements for receiving the force-producing device and for displacement thereof along a scale with percentage graduation, and with the force-producing device loading a lever of the proportional controller at a point of action which is displaceable along this lever, are arranged at a central control station. The central control station also includes a control device determining the entire product discharge of the mixing battery and which, for presetting a pressure which is variable in accordance with an increase or decrease in the calibrated total discharge output, is connected through control lines to the respective force-producing devices of the desired value setting devices of the control devices associated with the flow controllers.

The percentage proportion of a mixing component, to be supplied by a flow controller, in the total product discharge can be adjusted, in each case, at the control device associated with the flow controller. The subordination of all the control devices associated with the individual flow controllers to a further control device determining the entire product discharge of the mixing battery has the advantage that the total discharge output of the installation, once fixed by calibration, can be increased or reduced by a desired percentage to adapt to the fluctuating operating requirements. The mixing ratio of the components, once set, remains unaltered.

Further details of the arrangement will be made clear from the following detailed description of the appara- An object of the invention is to provide an improved flow controller for flowable products.

Another object of the invention is to provide such a flow controller which permits a precisely regulatable discharge of the product rapidly to particular output requirements.

A further object of the invention is to provide such a flow controller which is capable of remote control of the discharge of the product.

Another object of the invention is to provide such a flow controller which is free of disadvantages of prior art flow controllers of the same general type.

For an understanding of the principles of the invention, reference is made to the following description of a typical embodiment thereof as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a diagrammatic view of a flow controller embodying the invention as seen in the direction of the Arrow I of FIG. 2;

FIG. 2 is a side view of the flow controller as seen in longitudinal section through the regulating drive along II II of FIG. 1;

FIG. 3 shows the construction of the control nozzle;

FIG. 4 illustrates a first constructional variant for remote control;

FIG. 5 illustrates a second example for remote control operation; and

FIG. 6 shows a remote control arrangement intended for the construction shown in FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The flow controller of FIG. 1 has a balance beam 6 and an auxiliary beam 1 both pivotally connected to a fixed frame (not shown) by respective pivots 7 and 8 in the form of cross-spring bands. Auxiliary beam 1 carries a regulating weight 2 which can be displaced along a percentage scale 3 secured thereon. Also arranged on auxiliary beam 1 is a supporting edge 4 which can be finely adjusted longitudinally of auxiliary beam 1 by a threaded spindle or guide screw 5 disposed below the sliding path of adjustable weight 2 and parallel thereto. Supporting edge 4 bears on that lever arm of the balance beam 6 which is not subjected to loading by the outflow of product. This lever arm is provided with an adjustable counterweight 61, and its end remote from the load is formed as a baffle surface in front of the mouth 93 of a control nozzle 9 mounted below the lever arm on the fixed frame. Nozzle 9 comprises a connection 10 from a pressure medium source (not shown) for the supply, in this case, of pressure fiuid in the form of compressed air, and the nozzle also has a connection for an outgoing pressure conduit 11.

The construction of control nozzle 9 greatly influences the control precision of the flow controller. FIG. 3 shows the nozzle in cross-section. The nozzle entrance 91 is followed by a throttle portion 92 followed by a sudden widening 94 extending to nozzle mouth 93. For this sudden widening, a ratio of l:4 has been found suitable as the ratio between the cross-sectional area of throttle portion 92 and that of widening 94. It has also been found that pressure conduit 11 advantageously is connected directly to widened section 94.

In FIG. 1 and FIG. 2, an impact plate 14 is shown secured to the lever arm of the balance beam 6 at the load side. The shaping and the surface quality of impact plate 14 contribute to achieving the desired precision in control. By suitable selection of inclination, the nonlinearity, which occurs when there are load variations owing to different heights of fall for the individual product flow streams, can be eliminated, and the friction during impact can be coped with by suitable surface formation.

It has been found that the angle of inclination a of impact plate 14 relative to the horizontal is advantageously between 50 and 70, whereas the discharge portion 141 of that plate is inclined at an angle [3 45 relatively to the plane of the plate. An anti-friction coating 16 of polytetrafluoroethylene applied to the stainless steel plate largely overcomes disturbance due to friction. This combination results in a constant coefficient of friction both during and after the wearing down of the covering.

A closure member 13 is arranged on the fixed frame, spaced above impact plate 14, with an axis of rotation 133 extending in the same direction as balance beam 6. It comprises an outlet whose through-flow aperture 131 is situated on the generated surface of an imaginary cylinder described about axis of rotation 133, and narrows trapezoidally towards the impact plate 14, and a cylindrical rotary valve member 132 which passes below the through-flow aperture 131 by rotation about axis 133. The orientation of axis of rotation 133, because it is substantially parallel to the balance beam 6, results in leverage for the impact or impulse force which is constant with any loading.

FIG. 2 shows a cylinder-diaphragm system, of comparatively large volume, as a regulating drive 12 mounted on the fixed frame and having a large-surface diaphragm 121, with a return spring 122 secured to it and to the cylinder housing, and having a connecting rod 123 by means of which regulating drive 12 is coupled with closure member 13. Pressure conduit 11 leads from control nozzle 9 to regulating drive 12 by way of a hand-operated emergency closing valve 15 (see FIG. 1).

The apparatus described above operates as follows. Before starting operation, a single initial calibration is carried out, since the desired value of the product outflow is expressed as a percentage and is set by adjusting adjustable weight 2 along scale 3 on auxiliary beam 1. For a desired quantity (within the output range of the flow controller) expressed in terms of weight per unit of time, adjustable weight 2 is set to the percent mark. The counter-loading to the product outflow, which is thus obtained, is then balanced by adjusting the position of supporting edge 4 by means of guide screw 5 until the required weight quantity per unit of time is reached as measured on a calibrating balance arranged downstream of the apparatus.

If the product discharge during operation is only to amount to a fraction of the calibrated lOO percent weight quantity, adjustable weight 2 is displaced to the appropriate mark on the percentage scale 3. In the event of a plurality of such apparatuses used as parallel units in a mixing battery, each unit is calibrated in the manner described above for the 100 percent discharge quantity. Each unit then can be set to deliver the desired percentage of the mixture component controlled 6 by it, simply by displacement of its respective adjustable weight 2.

This method is particularly useful in grain mills, since these are designed to operate with a constant throughput. Calibration of the units is necessary only once. Of course, an apparatus of this kind can also be used for other bulk materials and liquids.

In addition to this correlation of desired quantities by weight with percentagewise desired-value setting, this apparatus permits extending the adjustment range, with small throughput quantities, by a factor of 10, thus achieving a substantially higher control precision.

Calibration of the apparatus eliminates the effect of variations in manufacture of the components of the controller, due to unavoidable tolerances, so that the production thereof is simplified and made less expen sive.

Means are also provided for ensuring substantially friction-free cooperation of the relevant parts, that is to say, hysteresis-free operation of the flow controller.

A first means is the arrangement of the supporting edge 4 in the horizontal plane through the respective pivots 7 and 8 of the balance beam 6 and auxiliary beam 1.

A second such means is constituted by the constructional arrangement of the control nozzle 9. The form of nozzle shown in FIG. 3, more particularly by bringing the control connection for regulating drive 12 to point 94 where the greatest pressure differences occur, provides the necessary conditions for allowing the pressure medium to flow out of the nozzle mouth 93 without any back pressure when its clearance from the balance beam 6 is quite small. This produces a powerful suction, through pressure conduit 11, in regulating drive 12, assisting the returning force of tension spring 122.

The digital-like behavior resulting from this pushpull" effect limits the amplitudes of the operational balance beam fluctuations in such a manner that the entire control path of balance beam 6 amounts to only a few tenths of a millimeter. The movement of supporting edge 4 on balance beam 6, swinging with only slight amounts of deflection, is then purely a rolling movement with negligible friction.

The digital operation also leads to further advantages. On the one hand, any fluctuations in the system pressure at nozzle entrance 9! are circumvented and thus have no influence on the precision with which control is effected. On the other hand, direct operation of regulating drive 12 is possible in this way without intermediate amplification.

The large-surface diaphragm 121 operates without friction as regulating drive 12. With its great volume, drive 12 also acts as a digital-analog converter, so that closure member 13 exhibits an analog control behavior when acting as a regulating unit.

Emergency closing valve 15, arranged in pressure conduit 11 between control nozzle 9 and regulating drive 12, is provided for immediate stopping of the control apparatus in the event of a fault. If an emergency closing operation is initiated, pressure conduit ll is blocked, but the pressure in regulating drive 12 is vented to atmosphere and closure member 13 closed by return spring 122. Since the product output thus falls off, the counter-loading due to adjustable weight 2 closes control nozzle 9.

After the emergency closing operation is discontinued, the pressure signal which builds up in pressure conduit 11 acts as an opening command at regulating drive 12 until balance beam 6 tilts under the impact of the rapidly increasing product output, and the movement about the position of equilibrium is once again resumed.

The arrangement of closure system 13, with its cylindrical rotary valve 132 and cylindrical-trapezoidal through flow aperture 13] disposed about the axis of rotation 133 which is substantially parallel to balance beam 6, insures that the distance of the linear center of gravity of all the product flow streams from pivot 7, and also the distance of the line of action of the impulse force resulting from the impact, both remain constant for any desired load setting.

The shaping of impact plate 14 with the angles of inclination given in the description of FIG. 2 contributes to an important extent to obtaining a behavior of the impulse or impact force which is proportional to load variations. FIG. 2 shows that the path lengths, along which the flow streams of falling product are again acceierated between the first and second impacts, decrease with increasing throughput. The differences in the height of fall of the flow streams are thereby compensated.

A further contribution to linearization is supplied by antifriction coating 16 of plastics material, which reduces friction.

A rational use of the apparatus as a unit in parallel operation as, for example, in a mixing battery with several units for several products is in practice conceivable only when operated by remote control from a central Control station.

FIGS. 4 and show two constructional forms for such applications. Regulating drive 12, closure member 13, impact plate 14 and pressure conduit 11 with emer' gency closing valve have been omitted here. The same reference numerals designate components identical or equivalent to those described with reference to FIG. 1 to FIG. 3.

In FIG. 4, the action of adjustable weight 2 is either reinforced, reduced, or completely replaced by a diaphragm drive arranged on the fixed frame. In the case of complete replacement, adjustable weight 2 must be set to a zero position. The remote-controlled pressure force, which can act on diaphragm 20 both in a positive sense and in a negative sense, is transmitted by means of a pivot 21 to an additional lever 22 of auxiliary beam 1.

FIG. 5 shows a construction involving an advanced degree of automation. Here, the diaphragm 200, pro vided in place of adjustable weight 2, is supported by a guide bar 17 mounted on the fixed frame and extending substantially parallel to auxiliary beam 1 above percentage scale 3. its adjustment along scale 3 is effected by means of a spindle 18 and a remote-controlled electric motor 19 both of which are also arranged on the fixed frame.

For the constructional forms shown in FIGS. 4 and 5, an emergency closing valve 150 (see FIG. 1) with remote operation is provided.

FIG. 6 shows the operating diagram of the two principal parts of an arrangement for the remote control of a multiproduct mixing battery with flow controllers according to FIG. 4. These are two

control devices

40, 40, which are arranged in a central control station LS and which have similar features as regards their apparatus layout. The first control device 40, allocated to one of the flow controllers, is itself controlled, together with those of the other flow controllers of the mixing battery, by the control device 40' for determining the currently desired adjusted total output of the installation. For simplicity, the other identical control devices 40 associated with the other flow controllers have not been illustrated.

Connected to the compressed-air conduit 23 in FIG. 6 is a control nozzle 24 which is constructed as shown in FIG. 3 and is incorporated in central control station LS. The control output 25 of nozzle 24 communicates by way of a conduit 26 with a force-producing device which is constructed as a diaphragm 27 and is incorporated in central control station LS. A lever 28, which is pivotally connected thereto and which is associated as a baffle plate with control nozzle 24, is coupled with diaphragm 27. A further lever 30, which is pivotally connected to a supporting plate 31, bears on lever 28 in such a manner that it can slide on the latter. A diaphragm 33, arranged on supporting plate 31 as a forceproducing device, presses on lever 30. Supporting plate 31 is mounted on a guide screw 34 by way of a spring loaded split nut 35, so that it can be displaced axially in either direction without play by rotating the guide screw 34. Guide screw 34 is carried by two bearings 36 mounted on central control station LS and is rotatable by a hand wheel 37. Also forming part of central control station L5 is a scale 38, with a percentage graduation from 0 to lOO percent, along which a pointer 32 carried by supporting plate 31 can move.

Apparatus elements 23 to 28 form a pneumatic regulator with proportional behavior and elements 30 to 38 provide a desired value setting means. The combination of this pneumatic regulator with such desired value setting means provides control device 40 which is operativcly connected, by way of a control line 29 starting from conduit 26 and from diaphragm 27, with the force'producing device constituted by diaphragm drive 20 of the associated flow controller according to FIG. 4.

Control device 40 is of a construction which corresponds to that of control device 40 already described, apart from the following features which will be described.

in the case of the proportional controller 23' to 28', which is otherwise constructed in a known manner, a tension spring 33" is additionally provided. This tension spring 33" is secured at one end to central control station LS and its other end is operatively connected to lever 28'. On supporting plate 31 of the desired-value setting means 30' to 38', which is otherwise also constructed in the manner hereinbefore indicated, another spring 33 is anchored, which acts as a pressure device and bears on lever 30'. Scale 38' of the desired value setting means 30' to 38' has a percentage graduation 2': 25 percent.

The operative connection between control device 40' and control devices 40 is constituted by

control lines

29', 29, 29" which start from line 26' and from diaphragm 27' of the proportional controller 23' to 28' and extend to the respective diaphragms 33 of desiredvalue setting means 30 to 38 of the respective control devices 40.

The arrangement described operates as follows. The pressure signal, acting by way of the associated control line 29 on the force-producing device constituted by diaphragm membrane 20 of a flow controller of the type shown in FIG. 4, is the basis for the desired value of a specific weight quantity per unit of time to be delivered by the flow controller. This pressure signal is formed by proportional controller 23 to 28 from the two active components, namely, pressure force and leverage. The pressure force is produced by diaphragm 33 in accordance with a pressure signal of proportional controller 23' to 28' supplied by way of the associated control line 29.

The leverage of the particular pressure force which lever 30 of desired value setting means 30 to 38 transmits to lever 28 of proportional controller 23 to 28 at the point of action of the two

levers

28, 30, can be determined by displacement of the point of action on lever 28. The displacement of the point of action is effected by positioning of supporting plate 31, together with lever 30 and diaphragm 33, by rotating guide screw 34 along scale 38 so that pointer 32 of supporting plate 31 is set to the percentage mark corresponding to the desired value. The pressure force coming from diaphragm 33 is transmitted, with the lever arm adjusted in this way, to lever 28 in such a transmission ratio that it maintains an equilibrium with the opposing force of diaphragm 27 exactly at that intensity, of the analog pressure signal going to each diaphragm drive 20, which is necessary for the intended desired value.

The analog pressure signal of proportional controller 23' to 28' of the overriding control device 40' for diaphragms 33 is produced in a similar manner to that for the diaphragm drives 20 of the associated flow controllers in the respective proportional controllers 23 to 28. The force component for the purpose, however, is suplied by the two springs 33' and 33". For 75 percent of the calibrated total output of the mixing battery, lever 28 of proportional controller 23' to 28' is preloaded by spring 33". The additional loading of lever 28', caused by the constant pressure force of spring 33', can be varied by displacement of supporting plate 31 together with lever 30' and spring 33', by rotating guide screw 34 corresponding to a variation of from to 50 percent of the calibrated total output. Pointer 32' of supporting plate 31' passes along scale 38' from 25 percent through 100 percent to 25 percent.

While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied other wise without departing from such principles.

What is claimed is:

1. In a flow controller for flowable products, particularly bulk materials, of the type having a closure member, of adjustable through-flow cross-section, arranged on a storage bin or a gravity discharge pipe, a regulating drive for regulating the through-flow cross-section, an inclined impact plate secured on a first lever arm of a balance beam in downwardly spaced relation to the closure member so that the impact force on the plate, due to deflection thereby of the product falling through a given distance, is proportional to the actual value of the flow rate of the product, expressed as quantity by weight per unit of time, the balance beam being pivotally connected intermediate its ends to a fixed frame and having at least one counterweight on a second lever arm remote from the impact plate, and an adjustable force-producing device acting on the balance beam in opposition to the impact force to regulate the through-flow cross-section with the deviation between desired value and actual value of flow rate of the product, resulting from the interaction between the impact force and the force-producing device being converted into a corresponding positive or negative pressure signal serving as a regulating signal for the regulating drive: the improvement comprising, in combination, an auxiliary beam pivotally connected separately to said fixed frame; the adjustable force-producing device loading said auxiliary beam; and a supporting edge mounted on said auxiliary beam for adjustment longitudinally thereof, and engaging said second lever arm of said balance beam to transmit, to said second lever arm, a precisely balanced proportion of the load produced by said adjustable force-producing means, indicative of the desired value of flow rate of the product, acting in opposition to said impact force.

2. In a flow controller, the improvement claimed in claim 1, in which said adjustable force-producing device is an adjustable weight displaceable longitudinally of said auxiliary beam; and a linear percentage scale extending longitudinally of said auxiliary beam and cooperable with said adjustable weight.

3. In a flow controller, the improvement claimed in claim 2, including a threaded spindle rotatably mounted on said auxiliary beam and extending parallel to said scale; said threaded spindle being threadedly engaged with said supporting edge to adjust said supporting edge longitudinally of said auxiliary beam.

4. [n a flow controller, the improvement claimed in claim 3, in which said supporting edge engages said second lever arm of said balance beam in substantially the plane including the respective pivots of the balance beam and the auxiliary beam.

5. In a flow controller, the improvement claimed in claim 1, in which said adjustable force-producing device includes a fluid pressure device for transmitting a remote-controlled fluid pressure force.

6. In a flow controller, the improvement claimed in claim 5, including a support secured to said fixed frame and extending substantially parallel to said auxiliary beam; said fluid pressure device being mounted on said support for adjustment therealong; a linear percentage scale extending longitudinally of said auxiliary beam and cooperable with said fluid pressure device; a threaded spindle rotatably mounted on said support and threadedly engaged with said fluid pressure device; and a motor connected to said spindle to rotate said spindle to adjust said fluid pressure device longitudinally of said support with respect to said percentage scale.

7. In a flow controller, the improvement claimed in claim 5, in which a plurality of said flow controllers, each controlling flow of a respective product, are arranged in parallel to provide a product mixture; a central control station for remote control of said flow controllers; respective first control devices for said flow controllers at said central control station; each first control device including a pressure medium operated proportional controller operatively connected, at an output side, through a respective control line with the adjustable force-producing device of a respective flow controller; a respective desired value setting means controlling each proportional controller; each desired value setting means including a subsidiary forceproducing device for converting a predetermined variable pressure into a force, and including elements to which such force is applied and arranged for displacement along a scale provided with a percentage graduation; each subsidiary force-producing device loading a lever of the associated proportional controller at a point of action along said last-named lever determined by such displacement; a second control device at said central control station for determining the total product output of all of said flow controllers; respective control lines connecting said second control device with respective subsidiary force-producing devices of the respective desired value setting means of the respective first control devices; said second control device, through said control lines, presetting a pressure which is variable to increase or decrease the total output of said flow controllers with respect to a predeter mined output rate.

8. In a flow controller, the improvement claimed in claim 1, in which said impact plate has a baffle surface which is substantially parallel to said balance beam and having a lower discharge portion extending at an angle toward the path of product flow along said baffle surface.

9. ln a flow controller, the improvement claimed in claim 8, in which the angle of inclination of the impact surface of said impact plate, relatively to the horizontal, is 60 1 and its discharge portion is inclined at an angle of substantially 45 to the impact surface.

10. In a flow controller for flowable products, particularly bulk materials, of the type having a closure member, of adjustable through-flow cross-section, arranged on a storage bin or a gravity discharge pipe, a regulating drive for regulating the through-flow cross-section, an inclined impact plate secured on a first lever arm of a balance beam in downwardly spaced relation to the closure member so that the impact force on the plate, due to deflection thereby of the product falling through a given distance, is proportional to the actual value of the fiow rate of the product, expressed as quantity by weight per unit of time, the balance beam being pivotally connected intermediate its ends to a fixed frame and having at least one counterweight on a second lever arm remote from the impact plate, and an adjust able force-producing device acting on the balance beam in opposition to the impact force to regulate the through-flow cross-section with the deviation between desired value and actual value of flow rate of the product, resulting from the interaction between the impact force and the force-producing device being converted into a corresponding positive or negative pressure signal serving as a regulating signal for the regulating drive: the improvement comprising, in combination, an auxiliary beam pivotally connected separately to said fixed frame; the adjustable force-producing device loading said auxiliary beam; a supporting edge mounted on said auxiliary beam for adjustment longitudinally thereof, and engaging said second lever arm of said balance beam, to transmit, to said second lever are, a precisely balanced proportion of the load produced by said adjustable force-producing means, indicative of the desired value of flow rate of the product, acting in opposition to said impact force; a plurality of said flow controllers, each controlling flow of a respective product, being arranged in parallel to provide a product mixture; a central control station for remote control of said flow controllers; respective first control devices for said flow controllers at said central control station; each first control device including a pressure medium operated proportional controller operatively connected, at an output side, through a respective control line with the adjustable force-producing device of a respective flow controller; a respective desired value setting means controlling each proportional controller; each desired value setting means including a subsidiary force-producing device for converting a predetermined variable pressure into a force, and including elements to which such force is applied and arranged for displacement along a scale provided with a percentage graduation; each subsidiary force-producing device loading a lever of the associated proportional controller at a point of action along said last-named lever determined by such displacement; a second control device at said central control station for determining the total product output of all of said flow controllers; respective control lines connecting said second control device with respective subsidiary force-producing devices of the respective desired value setting means of the respective first control devices; said second control device, through said control lines, pre-setting a pressure which is variable to increase or decrease the total output of said flow controllers with respect to a predetermined output rate; a control nozzle connected to a source of pressure fluid; said control nozzle being directed against said second lever arm of said balance beam in substantially the plane of movement of said balance beam; and a pressure conduit connecting said control nozzle to said regulating drive; said control nozzle, starting from its inlet end, merging into a throttle element and then abruptly winding into a widened portion followed by a portion extending to the nozzle dis charge mouth without substantial decrease in crosssectional area; said pressure conduit being connected to said nozzle at said widened portion closely adjacent said throttle element.

11. In a flow controller, the improvement claimed in claim 10, in which said nozzle has a constant crosssection flow area extending from said widened portion to the nozzle discharge mouth.

12. In a flow controller, the improvement claimed in claim 10, in which said regulating drive comprises a large volume cylinder having one end closed by a flexible diaphragm and having its opposite end formed with an inlet communicating with said pressure conduit; means biasing said diaphragm inwardly against the pressure exerted thereon from said pressure conduit; and a transmission rod connecting said diaphragm to said closure member.

13. In a flow controller, the improvement claimed in claim 12, including a manually controlled closing valve interposed in said pressure conduit between said control nozzle and said regulating drive; whereby, when said closing valve is closed, the supply of pressure fluid to said regulating drive is interrupted and said biasing force, acting on said diaphragm, effects closure of said closure member.

14. In a flow controller, the improvement claimed in claim 13, wherein said closing valve is a remotecontrolled electromagnetic valve.

15. in a flow controller, the improvement claimed in claim 12, in which said closure member includes a valve member in the form of a segment of a cylindrical casing and arranged to regulate an outlet flow aperture located on the generated surface of an imaginary cylinder concentric with said valve member and narrowing trapezoidally toward said impact plate.

16. in a flow controller, the improvement claimed in claim 15, in which said valve member is mounted for angular displacement about anaxis of rotation extending substantially parallel to said balance beam.

17. in a flow controller, the improvement claimed in claim 16, in which said impact plate is formed of stainless steel and has, on its baffle surface, an anti-friction coating of polytetrafluoroethylene.

18. The improvement claimed in claim 7, in which the subsidiary force-producing device of each desired value setting means comprises a diaphragm device 19. The improvement claimed in claim 7, in which the elements provided for receiving and displacement of said force-producing devices of the respective desired value setting means comprise, for each element, a supporting plate having a pointer mounting the associated force-producing device, in the form of a diaphragm device, a lever pivotally connected to the diaphragm device and bearing on the lever of the respective proportional controller; and a respective threaded spindle rotatably mounted at said central control station and threadedly engaged with the associated supporting plate to displace the associated supporting plate, without play, longitudinally of the associated percentage scale.

20. The improvement claimed in claim 19, wherein the associated scale of each desired value setting means has a percentage graduation from to 100 percent; the displacement of the point of action of each diaphragm device on the associated lever of the respective proportional controller being limited by two end settings corresponding, respectively, to the 0 and the 100 percent graduations.

21. The improvement claimed in claim 7, wherein said second control device for determining the total product output of the plurality of flow controllers includes a proportional controller and a desired value setting means identical to the corresponding elements of said first control devices.

22. The improvement claimed in claim 21, in which the proportional controller of said second control device includes biasing means connected between said central control station and the lever acting on the lever of the proportional controller, for static preloading.

23. The improvement claimed in claim 21, in which the desired value setting means of said second control device includes biasing means operative between its supporting plate and its movable lever for producing a constant pressure on its movable lever.

24. The improvement claimed in claim 23, in which the scale of desired value setting means of said second control device has a percentage graduation ranging from 75 to 125 percent, and the displacement of the point of action at which the biasing means of the movable lever bears on the lever associated with the proportional controller is limited by two end settings corresponding, respectively, to the 75 percent graduation and the 125 percent graduation representing the cali brated total output of the flow controllers.

25. In a flow controller for flowavle products, particularly bulk materials, of the type having a closure member, of adjustable through-flow cross-section, arranged on a storage bin or a gravity discharge pope, a regulating drive for regulating the through-flow cross-section, an inclined impace plate secured on a first lever arm of a balance beam in downwardly spaced relation to the closure member so that the impact force on the plate,

due to deflection thereby of the product falling through a given distance, is proportional to the actual value of the flow rate of the product, expressed as quantity by weight per unit of time, the balance beam being pivotally connected intermediate its ends to a fixed frame and having at least one counterweight on a second lever arm remote from the impact plate, and an adjustable force'producing device acting on the balance beam in opposition to the impact force to regulate the through-flow cross-section with the deviation between desired value and actual value of flow rate of the product, resulting from the interaction between the impact force and the force-producing device being converted into a corresponding positive or negative pressure signal serving as a frgulating signal for the regulating drive: the improvement comprising, in combination, an auxiliary beam pivotally connected separately to said fixed frame: the adjustable force-producing device loading said auxiliary beam; a supporting edge mounted on said auxiliary beam for adjustment longitudinally thereof, and engaging said second lever arm of said balance beam to transmit, to said second lever are, a precisely balanced proportion of the load produced by said adjustable force-producing means, indicative of the desired value of flow rate of the product, acting in opposition to said impact force; in a flow controller, including a fluid pressure device for transmitting a remote-controlled fluid pressure source; a plurality of said flow controllers, each controlling flow of a respective product, being arranged in parallel to provide a product micture; a central control station for remote control of said flow controllers; respective first control devices for said flow controllers at said central control station; each first control device including a pressure medium operated proportional controller operatively connected, at an output side, through a respective control line with the adjustable force-producing device of a respective flow controller; a respective desired value setting means controlling each proportional controller; each desired value setting means including a subsidiary force-producing device for converting a predetermined variable pressure into a force, and including elements to which such force is applied and arranged for displacement along a scale provided with a percentage graduation; each subsidiary force-producing device loading a lever of the associated proportional controller at a point of action along said last-named lever determined by such displacement; a second control device at said central control station for determining the total product output of all of said flow controllers; respective control lines connecting said second control device with respective subsidiary force-producing devices of the respective desired value setting means of the respective first control devices; said second control device, through said control lines, presetting a pressure which is variable to increase or decrease the total output of said flow controllers with respect to a predetermined output of rate; each said proportional controller including a respective control nozzle connected to a source of pressure fluid, and a flexible diaphragm device having a return force, the control nozzle and diaphragm device of each proportional controller being arranged at the central control station; a respective lever pivotally mounted at said control station and each connected to a respective diaphragm device for movement thereby as a baffle before the associated control nozzle; a respective control conduit connecting the control output of each nozzle with the associated dia decrease in cross-sectional area, the associated control conduit being connected to the widened portion of each nozzle immediately following the throttle element thereof.

Claims

4. In a flow controller, the improvement claimed in claim 3, in which said supporting edge engages said second lever arm of said balance beam in substantially the plane including the respective pivots of the balance beam and the auxiliary beam.

7. In a flow controller, the improvement claimed in claim 5, in which a plurality of said flow controllers, each controlling flow of a respective product, are arranged in parallel to provide a product mixture; a central control station for remote control of said flow controllers; respective first control devices for said flow controllers at said central control station; each first control device including a pressure medium operated proportional controller operatively connected, at an output side, through a respective control line with the adjustable force-producing device of a respective flow controller; a respective desired value setting means controlling each proportional controller; each desired value setting means including a subsidiary force-producing device for converting a predetermined variable pressure into a force, and including elements to which such force is applied and arranged for displacement along a scale provided with a percentage graduation; each subsidiary force-producing device loading a lever of the associated proportional controller at a point of action along said last-named lever determined by such displacement; a second control device at said central control station for determining the total product output of all of said flow controllers; respective control lines connecting said second control device with respective subsidiary force-producing devices of the respective desired value setting means of the respective first control devices; said second control device, through said control lines, presetting a pressure which is variable to increase or decrease the total output of said flow controllers with respect to a predetermined output rate.

9. In a flow controller, the improvement claimed in claim 8, in which the angle of inclination of the impact surface of said impact plate, relatively to the horizontal, is 60* + or - 10* and its discharge portion is inclined at an angle of substantially 45* to the impact surface.

10. In a flow controller for flowable products, particularly bulk materials, of the type having a closure member, of adjustable through-flow cross-section, arranged on a storage bin or a gravity discharge pipe, a regulating drive for regulating the through-flow cross-section, an inclined impact plate secured on a first lever arm of a balance beam in downwardly spaced relation to the closure member so that the impact force on the plate, due to deflection thereby of the product falling through a given distance, is proportional to the actual value of the flow rate of the product, expressed as quantity by weight per unit of time, the balance beam being pivotally connected intermediate its ends to a fixed frame and having at least one counterweight on a second lever arm remote from the impact plate, and an adjustable force-producing device acting on the balance beam in opposition to the impact force to regulate the through-flow cross-section with the deviation between desired value and actual value of flow rate of the product, resulting from the interaction between the impact force and the force-producing device being converted into a corresponding positive or negative pressure signal serving as a regulating signal for the regulating drive: the improvement comprising, in combination, an auxiliary beam pivotally connected separately to said fixed frame; the adjustable force-producing device loading said auxiliary beam; a supporting edge mounted on said auxiliary beam for adjustment longitudinally thereof, and engaging said second lever arm of said balance beam, to transmit, to said second lever are, a precisely balanced proportion of the load produced by said adjustable force-producing means, indicative oF the desired value of flow rate of the product, acting in opposition to said impact force; a plurality of said flow controllers, each controlling flow of a respective product, being arranged in parallel to provide a product mixture; a central control station for remote control of said flow controllers; respective first control devices for said flow controllers at said central control station; each first control device including a pressure medium operated proportional controller operatively connected, at an output side, through a respective control line with the adjustable force-producing device of a respective flow controller; a respective desired value setting means controlling each proportional controller; each desired value setting means including a subsidiary force-producing device for converting a predetermined variable pressure into a force, and including elements to which such force is applied and arranged for displacement along a scale provided with a percentage graduation; each subsidiary force-producing device loading a lever of the associated proportional controller at a point of action along said last-named lever determined by such displacement; a second control device at said central control station for determining the total product output of all of said flow controllers; respective control lines connecting said second control device with respective subsidiary force-producing devices of the respective desired value setting means of the respective first control devices; said second control device, through said control lines, pre-setting a pressure which is variable to increase or decrease the total output of said flow controllers with respect to a predetermined output rate; a control nozzle connected to a source of pressure fluid; said control nozzle being directed against said second lever arm of said balance beam in substantially the plane of movement of said balance beam; and a pressure conduit connecting said control nozzle to said regulating drive; said control nozzle, starting from its inlet end, merging into a throttle element and then abruptly winding into a widened portion followed by a portion extending to the nozzle discharge mouth without substantial decrease in cross-sectional area; said pressure conduit being connected to said nozzle at said widened portion closely adjacent said throttle element.

11. In a flow controller, the improvement claimed in claim 10, in which said nozzle has a constant cross-section flow area extending from said widened portion to the nozzle discharge mouth.

14. In a flow controller, the improvement claimed in claim 13, wherein said closing valve is a remote-controlled electromagnetic valve.

16. In a flow controller, the improvement claimed in claim 15, in which said valve member is mounted for angular displacement about an aXis of rotation extending substantially parallel to said balance beam.

18. The improvement claimed in claim 7, in which the subsidiary force-producing device of each desired value setting means comprises a diaphragm device.

19. The improvement claimed in claim 7, in which the elements provided for receiving and displacement of said force-producing devices of the respective desired value setting means comprise, for each element, a supporting plate having a pointer mounting the associated force-producing device, in the form of a diaphragm device, a lever pivotally connected to the diaphragm device and bearing on the lever of the respective proportional controller; and a respective threaded spindle rotatably mounted at said central control station and threadedly engaged with the associated supporting plate to displace the associated supporting plate, without play, longitudinally of the associated percentage scale.

20. The improvement claimed in claim 19, wherein the associated scale of each desired value setting means has a percentage graduation from 0 to 100 percent; the displacement of the point of action of each diaphragm device on the associated lever of the respective proportional controller being limited by two end settings corresponding, respectively, to the 0 and the 100 percent graduations.

24. The improvement claimed in claim 23, in which the scale of desired value setting means of said second control device has a percentage graduation ranging from 75 to 125 percent, and the displacement of the point of action at which the biasing means of the movable lever bears on the lever associated with the proportional controller is limited by two end settings corresponding, respectively, to the 75 percent graduation and the 125 percent graduation representing the calibrated total output of the flow controllers.

25. In a flow controller for flowavle products, particularly bulk materials, of the type having a closure member, of adjustable through-flow cross-section, arranged on a storage bin or a gravity discharge pope, a regulating drive for regulating the through-flow cross-section, an inclined impace plate secured on a first lever arm of a balance beam in downwardly spaced relation to the closure member so that the impact force on the plate, due to deflection thereby of the product falling through a given distance, is proportional to the actual value of the flow rate of the product, expressed as quantity by weight per unit of time, the balance beam being pivotally connected intermediate its ends to a fixed frame and having at least one counterweight on a second lever arm remote from the impact plate, and an adjustable force-producing device acting on the balance beam in opposition to the impact force to regulate the through-flow cross-section with the deviation between desired value and actual value of flow rate of the product, resulting from the interaction between the impact force and the foRce-producing device being converted into a corresponding positive or negative pressure signal serving as a frgulating signal for the regulating drive: the improvement comprising, in combination, an auxiliary beam pivotally connected separately to said fixed frame: the adjustable force-producing device loading said auxiliary beam; a supporting edge mounted on said auxiliary beam for adjustment longitudinally thereof, and engaging said second lever arm of said balance beam to transmit, to said second lever are, a precisely balanced proportion of the load produced by said adjustable force-producing means, indicative of the desired value of flow rate of the product, acting in opposition to said impact force; in a flow controller, including a fluid pressure device for transmitting a remote-controlled fluid pressure source; a plurality of said flow controllers, each controlling flow of a respective product, being arranged in parallel to provide a product micture; a central control station for remote control of said flow controllers; respective first control devices for said flow controllers at said central control station; each first control device including a pressure medium operated proportional controller operatively connected, at an output side, through a respective control line with the adjustable force-producing device of a respective flow controller; a respective desired value setting means controlling each proportional controller; each desired value setting means including a subsidiary force-producing device for converting a predetermined variable pressure into a force, and including elements to which such force is applied and arranged for displacement along a scale provided with a percentage graduation; each subsidiary force-producing device loading a lever of the associated proportional controller at a point of action along said last-named lever determined by such displacement; a second control device at said central control station for determining the total product output of all of said flow controllers; respective control lines connecting said second control device with respective subsidiary force-producing devices of the respective desired value setting means of the respective first control devices; said second control device, through said control lines, presetting a pressure which is variable to increase or decrease the total output of said flow controllers with respect to a predetermined output of rate; each said proportional controller including a respective control nozzle connected to a source of pressure fluid, and a flexible diaphragm device having a return force, the control nozzle and diaphragm device of each proportional controller being arranged at the central control station; a respective lever pivotally mounted at said control station and each connected to a respective diaphragm device for movement thereby as a baffle before the associated control nozzle; a respective control conduit connecting the control output of each nozzle with the associated diaphragm device; the cross-section of each further control nozzle, starting from the nozzle inlet, merging into a throttle element followed by an abrupt widening to provide a widened portion connected to the discharge mouth of the nozzle by a portion without substantial decrease in cross-sectional area, the associated control conduit being connected to the widened portion of each nozzle immediately following the throttle element thereof.