US2299959A - Control system - Google Patents

Description

ct. 27, 1942. H, w, BRENTZ 2,299,959

CONTROL SYSTEM BYWMW Oct. 27, 1942. H, w, BRENTZ 9 2,299,959

CONTROL SYSTEM H. W. BRENTZ CONTROL SYSTEM Filed April 8, 1941 3 Sheets-Sheet 3 Patented Oct. 27, 1942 UNITED STATES PATENT OFFICE 21 Claims.

This invention relates to control systems and devices in general, and is particularly concerned with but is not limited to a control device for governing the operation of a separator. The invention may be considered in the nature of an improvement on the control device disclosed in my U. S. Patent No. 2,270,696, issued January 20, 1942.

A brief review of the prior art and of the system and device disclosed in the above noted copending application is rendered below, so as to support the understanding of the description of the present case which is to follow. This review and the disclosure of the invention refer for illustrative and explanatory purposes to certain types of separators wherein comminuted material, for example, coal, is separated in a gravity separation process so as to free the coal from admixtures and impurities usually found in the coal as it comes from the mine. This reference to specific types of separators, however, is not intended to indicate any particular limitation, pointing either to the use of the invention or to a specific type of apparatus or operation which it may control.

The customary gravity separator comprises a chamber for receiving the material for separation, suitable pneumatic or hydraulic means, used either alone or in conjunction with mechanical means, for agitating the material, whereby the material bed is moved and its different components are caused to stratify according to the different specic gravities of the particles. In a coal separator or washer of this kind the cleanv coal, due to this agitation, seeks the highest level, particles of intermediate specic gravities, termed middlings, such as bony coal and the like, collect in a layer underneath the coal, and the heaviest particles, such as rock, slate, pyrite, etc., seek the lowest level in the separating chamber. These materials may be withdrawn by way of separate discharge chutes.

Such a separator or jig is usually equipped with suitable supply and discharge gates or valves; a pawl and ratchet operated discharge valve or gate may be employed for removing the heavy material. This gate or valve may be made in the form of a star wheel or the like which is rotated through the medium of a reciprocating pawl actuating a ratchet attached to its shaft The pawl may be constantly reciprocated at a substantially uniform rate while the separator is in operation, thus tending to rotate the discharge valve at a uniform speed to remove or discharge the heavy material from the separating chamber at a correspondingly substantially uniform rate.

The operation so far described is well known. It does not meet modern operating requirements because it is basedon the assumption that the separation or stratification of the material progresses uniformly, yielding uniform amounts of material in the several strata, and particularly in the lower strata forming in the separating chamber. Such uniform separation does not occur in practice.

Attempts have been made to remedy this situation by providing a variable control for the discharge gate. Among these attempts may be mentioned the patent to Elmore, No. 1,132,464, showing a structure wherein the pawl for rotating the ratchet of the discharge wheel is made in the form of an armature placed so that it may be attracted by an electromagnet. The energization of this magnet is controlled by relays, and these in turn are governed by a oat operated switching device in such a manner that the electromagnet energizes and withdraws the pawl from the ratchet to prevent rotation of the discharge wheel so as to allow material to accumulate in the separating chamber at the time when the material level is low. Other suggestions along these lines `are contained in Attwood Patent 2,132,380 which discloses a float controlled, Wholly mechanical, arrangement for governing the operation of the pawl with reference to the ratchet of the discharge wheel, and in the patent to Burnell et al., No. 2,106,204, which uses for the same general purpose electrical and mechanical oat controlled equipment, including photoelectric cells responsive to variations in the material level.

In my previously mentioned patent I provide in the separating chamber a freely movable iloat and alongside the float stem a plurality of lever arms adapted to be actuated by trip means on the stem in accordance with the position of the float indicating the depth of the material layer, which serves as a criterion for the operation of the control. The lever arms in turn govern the circuits of two electromagnets, one adapted to control the engagement and disengagement of the pawl with regard to the ratchet of the discharge wheel, and the other adapted to control the effective operative throw of the pawl. The system shown in my said patent thus provides a simple combination of electrical and mechanical means for causing the pawl to rotate the ratchet and thereby the discharge gate or wheel or to prevent its rotation, and to accelerate or slow up the rotation by increasing or decreasing the throw of the pawl, all in accordance with the needs of the separator as indicated by the level of a material layer in the separating chamber.

The present invention proceeds from the same basic observations, but provides a variable automatic control which is believed to be more sensitive, more accurate, more reliable, and at the same time simpler than any previously devised control equipment of this type. This new control can be used with any of the known separators and will improve its operation.

The new and improved control, in common with other systems, uses a oat which is disposed in the separating chamber and is equipped with a stem provided with trip rings. The float responds to the uctuations of the material level which serves as a criterion for governing the control operations. Alongside the float stem is disposed a movably mounted switch comprising contact actuating lever arms which may be engaged by the trip means on the float stem, responsive to the rise or fall of the float. There are two such lever arms, each governing the operation of contact means provided for the operation of separate electromagnets which in turn are adapted for controlling the operation oi the discharge valve responsive to the rise or fall of the float, respectively. These electromagnets actuate ratchets for rotating a shaft in one orthe other direction, depending on the response of the oat, and the motion of the shaft is transmitted by a worm gear to another shaft carrying crank disks, one for shifting the movable switch and the other for moving a shield so as to adjust the position of the pawl with respect to the ratchet which operates the discharge gate.

rlhe operation may be briefly described as iollows: The float rises or falls with the material level in the separating chamber, actuates one of the contact means oi the movable switch, giving a. rIhe movable switch disposed alongside the iioat stem is raised or lowered in the direction of the displacement of the float;

b. The pawl which controls the discharge gate ratchet is moved with respect to the ratchet so as to dispose it for operating the gate to compensate for the changes in the separating chamber which caused the displacement of the float.

The operative response of the discharge gate is gradual and variable, slowing up when the material level drops, actually stopping the discharge in case the material level reaches a predetermined low point so as to give time for building up the proper material bed, and contrariwise, gradually increasing the operative throw of the pawl f so as to accelerate removal of material in response to a rise of the material bed. The discharge is thus approximated to and is varied with the fluctuation of the material bed in the separating chamber in a very sensitive and accurate manner in accordance with the needs of the separator that may at any time prevail.

The above brief outline touches only the principal structural and functional features of the invention. Others will be brought out in the i.

course of the detailed description which is rendered below with reference to the accompanying drawings showing, for illustrative purposes, an embodiment of the invention in conjunction with a known type of separator. Zin these drawings,

Fig. l shows a fragmentary view of a separator, with a float separating chamber and one end of the control device with its movable switch disposed adjacent the float stem;

Fig. 2 illustrates the control device from the opposite end, showing the link to the pawl operating mechanism and a fragmentary diagrammatic view of the discharge valve;

Fig. 3 indicates a top view of the salient parts of the control device;

Fig. i is a front view of the device, as seen along the lines -i in Fig. 3;

Fig. 5 represents, on an enlarged scale, the pawl and ratchet assemblage for actuating the control shaft of the device;

Fig. 6 shows, on an enlarged scale, a circuit breaker which operates in the nature of a limit stop;

Fig. 7 illustrates the Contact assemblage of the circuit breaker, as seen along line 'l-'l in Fig. 6;

Figs. 8 and 9 indicate, on an enlarged scale, the structure of the movable switch; and

Fig. l0 represents the circuit diagram for the device.

Like reference numerals indicate like parts throughout the drawings. Elements, the structure and operation of which may be assumed to be well known in the art, will be described only to the extent required for supporting the understanding of the invention.

Referring now to the drawings, particularly Fig. l, numeral i Il indicates in a diagrammatic manner part of the separating chamber of a separator. The bottom l2 of this chamber may be provided with perforations so as to admit a medium, for example, air or water for agitating material supplied to the chamber li. Mechanical agitating means may be provided if desired. The material separates and stratiiies in the chamber i! according to the specific gravities of the particles, as previously explained and as is well known, and at the same time moves toward the discharge end which is assumed to be at the right side of Fig. l. The heavy material collects at the bottom of the separating chamber and iinally moves into the discharge chute I3. The light material, which in the case of a coal separator is the clean coal, is discharged by way of the overilow it. Separate discharge means may be provided for the middlings.

The float i5 having a stem E6 which is mounted freely movable between the supporting plates Il and i8 may be disposed as shown. The oat may be of the type and may be mounted as particularly described in my previously mentioned co-pending application. However, diierent suitable structures may be used for the mounting as well as for the float. At its upper end the float stem or an extension thereon may be graduated as indicated in Fig. 1, and a stationary pointer i9 may be provided to coact with the markings so as to indicate visually the condition of stratication in the separating chamber. If it is assumed that the control is to be governed in accordance with the level of accumulated heavy material, then the float is made or is properly weighted so as to simulate the specific gravity of the lightest components of this heavy material. Accordingly, the float will tend to move with the heavy material layer, and will at any time indicate the depth of this layer in the separating chamber.

The discharge chute I3 may be provided with a gate or valve which is assumed to be a simple rotatable star wheel or the like having spokes 2l), the wheel being mounted on a shaft which carries a ratchet 22, as indicated in Fig. 2. This wheel, upon rotating, discharges the heavy material into an elevator compartment formed by the walls 2| indicated in Fig. 2 in dotted lines. On the discharge wheel shaft is also mounted a double-armed lever 23 carrying a pawl 24. This lever may be oscillated through the medium of the link 25 attached to a bearing 26 which is rotated by an eccenter 21. The latter may be constantly rotated, during the operation of the separator, by a shaft 28 actuated by suitable motor means. Assuming this to be the case, the pawl 24 will be reciprocated at a substantially constant rate, and will thus tend to rotate the discharge gate at the uniform rate to obtain a substantially uniform rate of discharge of heavy material from the chute I3 into the elevator compartment defined by the walls 2|.

It is the object of the invention to control the separator through the medium of the discharge gate in such a manner that the discharge is at any time a function of the actual stratification conditions within the separating chamber. Upon starting the operation, and assuming that the separating chamber is empty, there should be no discharge until a material layer of desired depth has accumulated. At this moment the operation of the discharge gate should be started, and should be maintained at such a variable rate as to keep up with or conform to the varying stratification conditions..

The new control device which accomplishes this object comprises a shaft 30 (Figs. 2, 3, 4) mounted in suitable bearings 3| on a bed plate 32 which may be part of the separator structure or may be attached thereto. The shaft 30 is flexibly coupled at 33 with a shaft 34. At the end of shaft 30 is attached a crank disk 35, and the shaft 34 carries at its end a crank disk 36. The shaft 34 is rotatably mounted in a bearing 31 carried on a standard 38 which may be adjustably attached at 3S to the bed plate I1.

The crank disk 36 is connected with the switch 40 through the medium of the link 4| (Figs. l, 3 and 4). The crank disk 35 is coupled with the rotatable pawl control shield 42 through the medium of the link 43 (Figs. 2 and 4). The shield 42 is rotatably mounted on the shaft carrying the rotary discharge valve and is provided with an extension 44 adapted to slide under the pawl 24 and to lift this pawl entirely out of engagement with the ratchet 22, or if properly moved in counter-clockwise direction as seen in Fig. 2, to permit the engagement of the pawl 24 with the ratchet 22. Thus, by manipulating the shield 42/44 the engagement of the pawl 24 can be entirely prevented and rotation of the discharge valve can be stopped, or it can be permitted to any desired extent, within certain limits. In other words, the extension 44 of the shield .42 controls the positioning of the pawl 24 with respect to the ratchet 22 in such a manner as to govern its engagement or disengagement, and also to govern its operative throw. As shown in Fig. 2, the crank disk 35 is provided with a number of radially disposed apertures for the attachment of the link 43 so as to adjust the angular displacement of the link 43,

and the disk 36 (Fig. 1) is likewise provided with a number of radially disposed apertures for the adjustable attachment of the link 4 I.

The device thus permits a manipulation of the shield 42/44 for governing the positioning of the pawl 24 to control the operation of the discharge wheel ratchet 22 shown in Fig. 2, and also permits simultaneous shifting or vertical displacement of the switch 4|) shown in Fig. 1. Before continuing the description of the control device, we will point out the structure of the switch 4|), particularly with reference to Figs. 1, 8 and 9.

The switch is shown in these figures in a more cr less diagrammatic manner. It may comprise the mounting plate 4D provided with a bracket 50 which furnishes bearings for the angularly shaped lever arms 5| and 52. The first noted lever arm carries a roller 53, and the other arm carries a roller 54 for engagement with the trip rings 55 and 56, respectively, on the float stem I6. The lever arm 5I carries or is equipped with a contact spring 51, and the lever arm 52 is similarly provided with or operates a contact spring 53. It is, of course, understood that these contact springs 51 and 58 are in insulated relation to the lever arms. The electrical conditions will be discussed later on in connection with explanations to be furnished for Fig. 10. A bracket 6U carries contacts 6| and 62 for cooperation with contacts 63 and 64 on the springs 51 and 58, respectively. The bracket is mounted in insulated relation to the switch plate 40 by means of a member 65. The weight of the roller 53 keeps the lever arm 5| in the position shown in Fig. 8 with a contact 63 normally out of engagement with contact 6|. A counterweight 61 is attached to the lever arm 52 so as to keep this lever in such a position that the contacts 64 and 62 are normally out of engagement. Grooved or V- shaped rollers 10, 1|, 12 and I3 are rotatably secured to the other side of the plate 40, as shown in Fig. 9. The entire switch is movably mounted between two suitably shaped guides 15 and 16 (Figs. 1 and 8), which in turn are mounted between the bed plate |1 and the top mounting plate I8. The link 4I (Fig, 1) is suitably attached to the base plate 40 of the switch. Therefore, responsive to rotation of the shaft 34 (coupled at 33 with shaft 30) and consequent rotation of the crank disk 36, the link 4| will move the entire switch with its contacts and contact operating levers up or down, depending on the direction in which the shaft is rotated.

The direction of rotation of the shaft 34 (and with it shaft 30 flexibly coupled therewith) is governed by the rotation of the control shaft in response to the actuation of one or the other of the electromagnets 8| and 82. These electromagnets are controlled by the actuation of the contacts 51 and 58 which in turn are governed through the medium of the lever arms 5I and 52. The latter are displaced, as mentioned above, by the trip means 55 and 56, respectively, when the float I5 rises or falls in accordance with the accumulation or the decrease of material in the separating chamber. In order to limit the extent of rotation of the switch operating levers 5| and 52, these levers are provided with apertures and IDI, respectively, and through these apertures project the pins |02 and |63 which are fixedly mounted on the plate 40. These pins are therefore in the nature of limit stops controlling the angular displacements of the lever arms 5| and 52.

The control shaft 80 is rotatably mounted in bearings 83, 84 and 85 (Figs. 2, 3 and 4). It

carries a worm gear 86 (Fig. 4) which meshes with a worm gear 8l lkeyed to the shaft t. The shaft S@ also carries a ratchet 88 which is rotated by a pawl 89 operated by the electromagnet 8i, and anotherr ratchet 9) adapted to be actuated by a pawl 9E which is operated by the electromagnet B2. These pawls are in each instance rotatably mounted in a yoke, the yoke for the pawl 8S being indicated at 93 in Figs. 2 and 3, and the yoke for the pawl 9i being indicated at 94. The yoke may contain or may operate as a detent.

One assembly cf the yoke and pawl for cooperation withthe magnet 8l is indicated on an enlarged scale in Fig. 5. The ratchet 88 is keyed to the shaft 33, and the yoke 93 rotatably embraces this ratchet'as shown. The pawl 89 is rotatably mounted in this yoke 93 at 5, and carries an extension 96 to which may be attached the link 9i'. This link connects with the magnet El. The attachment may be, made at various points by means of the apertures provided in the extension 96 so as to adjust the desirable leverage in accordance with any particular working conditions. and pawl mechanism 94 and 9i controlled by the magnet 82 is similar to and includes thc pawl extension Q8, as shown particularly in Fig. 4. The mounting plate 32 shown in Fig. 5 is also provided with screws d, one for each of the yokes B3 and. The electromagnets 8i and S2 may be solenoids, and each may be mounted on a separate bracket such as indicated in the drawings.

When the oat i rises in response to accumulation of material, it will reach a position where the trip member 55 contacts the roller 53 to tilt the lever arm El in clockwise direction, thereby closing the switch contact points 53 and 6l. This results in energization of the electromagnet or solenoid 8| which attracts its armature and rotates the arm 95 and thereby the pawl 89 in counter-clockwise direction (Fig. 5). The pawl engages the ratchet S8 and rotates it and therewith the shaft-853 (Figs. 2, 3, 4) in counter-clockwise direction. The worm @6 on the shaft 8i) consequently transmits the rotary motion through the worm gear 8l to the shaft 3D and through the flexible coupling 33 to the shaft 34. Both the crank disk 35 and the crank disk 35 are rotated by an amount determined by the rotation of shaft 8@ as transmitted by the ratio of the gear /S'l. The amount of rotation will be relatively small as it corresponds only to onestep rotation of the ratchet 88.

The rotation of these crank disks in turn causes a shifting of the switch 40 upwardly along the guides l5 and', and simultaneously a motion of the link it (Fig. 2) downwardly, to effect a counter-clockwise displacement of the shield 44 with respect to pawl 24. The shield d4 is thus withdrawn a certain relatively small amount from under the pawl Z4, conditioning or disposing the pawl toward engagement of the ratchet 22 by a corresponding amount. This is the proper response because it was assumed that the material in the separating chamber accumulated and lifted the float; therefore, the response must be a control that provides for actuation of the discharge gate.

Contrariwise, when the material level in the separator chamber drops, a point is finally reached when the trip member 5S trips the roller 54 to rotate the switch arm 52 in counter-clockwise direction. Thisv closes the contacts 62 and The assemblage of the other yoke 64 to give an impulse to the electromagnet or solenoid 22. Upon energizing, the magnet 82 attracts its armature and actuates the pawl SI through the medium of the extension 93 (Figs. 3, 4 and l0). The pawl 9i now rotates the shaft in reverse direction. This rotary motion is transmitted through the worm gear 86/37 to the shafts 30 and 34. Now, since the shafts rotate in reverse direction, the crank disk 35 lowers the switch 46 (Fig. 1) a corresponding amount, and the crank disk 35 (Fig. 2) lifts the link 34 to rotate the shield 44 in clockwise direction so as to dispose the pawl 24 in a direction toward inhibiting the operative engagement of the pawl 24 by a corresponding amount. rIhis latter operation again constitutes a proper response to the conditions in the separating chamber, since it was assumed that the material lever was lowered, and if such is the case, the removal of material by the discharge gate must be decelerated or, if the material level continues to drop, it must be finally inhibited. A complete operating cycle will be presently described, after completing the explanations with respect to the structural and electrical features of the apparatus.

It is desirable to provide for some limiting means so as to control the operation in the extreme positions that may be reached in practice.

- I have provided for this purpose circuit breakers such as indicated in general in Figs. 3 and 10 and shown in detail in Figs. 6 and 7. The circuit breaker (Figs. 6 and 7) comprises a member H0 secured to the shaft 30 so as to be rotatable with it. Contact springs lll and I l2 are mounted on the insulating member l I3 attached to the base 32 by means of a suitable standard H4. The lower contact spring H2 is provided with an extension H5 for engagement with the arm HS projecting from the insulating member IEE). The contacts on the springs HI and H2 are normally in engagement and closed. Assuming now that the shaft 39 shown in Fig. 6 rotates in counter-clockwise direction, it will finally reach a point when the member H6 contacts the spring extension H5 and depresses the lower spring H2 so as to open the contacts and thereby a certain control circuit. This limit point is reached when the material level in the separating compartment has reached the highest possible or desired and predetermined operating level. In-gradually rising to this level, the material level has lifted the float and has produced successive impulses effective to the solenoid 8l which in turn produced a gradual rotation ofthe shaft 80 and thereby gradual geared rotation of the shafts 3E) and 34 so as to compensate for the rise in the material level by accelerated operation of the discharge Valve through the medium of pawl 24. The pawl now is so positioned that it has the greatest throw and the discharge valve or gate is therefore rotated at the maximum speed to remove the maximum volume of material. When this limit condition is reached the Contact springs Ill and H2 (Fig. 6) open as a control means for the proper operation of the system in reverse direction. The material level in the separating compartment will be gradually reduced, due to the accelerated rapid discharge action, and therefore the trip member 5t will successively contact the roller 54 and produce successive operative actuation of the solenoid 82 which will cause a reverse rotation of the shafts 3i? and 34 to gradually slow down the effective operation of the discharge valve. During this reverse operation the shaft 3U (Fig.

6) rotates in clockwise direction, and after a time restores the normal closed position of the contact springs and ||2 (Figs. 3 and 6).

Another such circuit breaker is indicated in Fig. 3 at |20 and |2|. It comprises parts substantially like those shown in Figs. 6 and 7 eX- cept that the lever arm |23 is mounted so as to operate contact springs of which one is shown at l2| when a limit position is reached responsive to a clockwise rotation of the shaft 38. This latter limit position is reached when the material level is at the lowest possiible or desired and predetermined operating level.

A cycle of operation is explained below with reference to the various drawings and also taking into consideration the circuit diagram shown in Fig. 10.

Let us assume that the separating compartment is empty or practically empty when the operation of the separator is started. The float then is at or near the lowermost limit position. The switch assemblage 43 is also at or near its lowermost limit position, having been lowered along the guides 15 and 1S by the rotation of shaft 34 and crank disk 36 in response to the gradual emptying of the separating chamber and coincident gradual lowering of the float. The shield 44 (Fig. 2) is positioned underneath the pawl 24, somewhat as shown in the drawing, having disposed the pawl so as to inhibit eifective operation of the ratchet 22 and therefore of the discharge Wheel. The shaft 28 operating the eccenter 21 so as to oscillate the arm 23 to reciprocate the pawl 24 may be rotated upon starting the machine, but such reciprocation will be without effect. The limit circuit breaker comprising the arm |23 and contact spring |2| is in its operative limit position keeping the circuit to the solenoid 82 open at Contact point |25 (Fig. l0).

As the material builds up in the separating chamber the iioat l5 rises until finally a depth or level of the material is reached at which the control operation should be initiated so as to start the discharge. At this moment the trip ring 55 on the float stem l5 engages the roller 53 and rotates the Contact lever 5| in clockwise direction to close the circuit at contacts 53 and 6| (Fig. 10) from the positive pole of the current source by way of conductors |25, |21, closed limit switch contacts |l2 and |28, conductor |29, electromagnet 8|, conductor |38, back to the negative pole of the current source. It may be assumed, of course, that a suitable control switch is positioned in the main conductors of the system so as to switch the current on and olf as desired. This control switch may also connect the motor means for rotating the shaft 28 (Fig. 2) to reciprocate the pawl 24. The solenoid 8| receives an impulse responsive to the closure of contacts (i3-GI and actuates the ratchet 88 through the medium of the pawl 89 to rotate the shaft 80. This rotation is transmitted through the positive worm gear drive 86 and 81 to the shaft 30 and through the flexible coupling 33 to the shaft 34. These shafts now rotate in a direction so as to lift the switch assemblage 40 to compensate for the raising of the float and so as to condition or to prepare the effective operative engagement of the pawl 24 with the discharge gate operating ratchet 22.

The entire switch assemblage 4i) is thus displaced to follow the lifting motion of the float during the time when material accumulates. This switching device is lowered by the same means responsive to the downward motion of the iioat during the time when Vthe material level drops. This is a particularly advantageous feature of the invention because it permits a graduated and gradual positive control in accordance with the needs of the machine and does it with the least expenditure in equipment. A slippingback or even a tendency ofthe switch assemblage to slip back from any position to which it has been lifted and an undesirable or inadvertent displacement of the shield 44 with respect to pawl 24 that may interfere with the proper control operations are prevented by the positive action which results from the use of the worm' gear drive. This drive can be so dimensioned as to provide for any desired ratio in the'transmission of rotation from shaft Si) to shaft 30/34.

The magnet 2| deenergizes again as soon as the above noted operations (lifting of the contact assemblage and shifting of shield 44) are completed. The amount of lift of the contact assemblage is adjustable by the positioning of the link 4| on the crank disk 36 and the amount of displacement of shield 44 with respect to the pawl 24 is also adjustable by the placement of the link 43 on the'crank disk 35. Whether or not the pawl is operatively effective in response to this rst impulse given to the electromagnet 8| will depend on the predetermined adjustment which is made in accordance with the desired depth of material layer at which the machine should begin to discharge. The amount of displacement may be very small with each step and may be adjusted within certain limits given by the over-all size of the crank disks, the leverage of the shield 42 and the gear ratio provided for by the worm gears 86, 81.

The material level continues to rise until another engagement of the trip ring with the outer end of the contact lever 5| is obtained and another current impulse is transmitted to the solenoid 8|. The shaft 83, therefore, is again rotated, transmitting its rotation by means of the worm gears to the shafts 30 and 34. As a consequence the switch assemblage is again lifted by a certain amount, and the shield 44 is additionally displaced with respect to the pawl 24 in a direction so as to start or continue or to increase the operative engagement of the throw with respect to the ratchet 22.

The control operation proceeds in this manner, the rising material level in the separating compartment producing successive impulses for the solenoid 8| and the solenoid in turn rotating the operating shafts to take care of a compensating lift of the contact assemblage and a compensating displacement of the pawl shield so as to increase the e'ective operative engagement of the pawl `with the ratchet and to accelerate the operation of the discharge gate as the need arises. At a certain point of the cycle of operation, the pawl will engage only one tooth of the ratchet 22. Should the material level increase, the pawl will be so positioned by the control of the shield that it engages two or three or even more teeth, thus speeding up the discharge, in accordance with the speeding up of the accumulation of material in the separating chamber.

The limit circuit breaker controlling the contacts |2/ 28 comes into operation when the high level limit position of the material in the separating chamber is reached. Referring to Fig. 10, the arm IIE engages and depresses the spring l|2 and opens the circuit at the contact point |28. No further impulses can nowA be sent over the conductor |29 to the solenoid 3|. The circuit for the solenoid 82, however, is not affected. The limit circuit breaker for the low material level position comprising the arm |20 is now farthest away from the contact spring |2|, keeping the circuit between this spring and contact point |25 closed. The machine noW operates at maximum discharge capacity which can be provided for any material conditions to be suicient to reduce the material bed in the separating compartment to a desired normal operating level.

Responsive to lowering of the material bed and consequent dropping of the float l5, the control system is aifected so that it operates in reverse direction. The magnet 82 now receives successive impulses responsive to successive engagement of the trip ring 56 with the roller 54 which tilts the contact lever arm 52 in counter-clockwise -direction to close the circuit for the magnet 82 by way of conductors |2, |40, closed circuit breaker contacts |.2|, |25, conductor lill, solenoid 82, and back to the current source by way of conductor |30. These successive impulses cause successive operation of solenoid B2 to rotate the shafts 80 and Sil- 3i successively in the reverse direction so as to lower the contact switch assemblage 40 gradually and to displace the shield 44 gradually with respect to the pawl in a direction to gradually Icut down, or in the extreme low limit position to inhibit the effective operative engagement of the pawl with the discharge gate ratchet. In this low level limit position the limit circuit breaker controlling the contacts |2|/ |25 is operated, opening these contacts. No further impulses can `now be transmitted to the magnet 82. The circuit of magnet 8| is not affected because the high level :circuit breaker contacts ||2/|28 are closed. The material can now accumulate in the .separating chamber because the discharge is stopped. As soon as the level of the material bed is at a desired point, the discharge is started again in the previously :described manner.

The new system thus provides a very sensitive control which follows the changes in the depth of the material bed in the separating compartment very accurately and governs the discharge or release of material at any time in an amount sufficient to compensate for such changes, that is, in accordance with the needs of the machine. The system is simple in structure and accurate in operation. It can be easily 4produced at very reasonable cost and does not require any particular maintenance. The .switching Ydevice or assemblage 4|) can be put into a suitable casing so as to protect it from .dust and injury. The r mechanical control apparatus can ,also easily be put in a suitable protective housing from which protrude merely the crank disk 35 and the shaft 34 with its crank disk 36. An extension of this housing may even include the flexible coupling 33, the shaft .34 and 4also the .bearing 3l in an obvious manner. There are thus no parts exposed to injury or contamination that could cause any trouble.

There is also shown in Figs. 2 and 3 a hand Wheel |58 which is attached to the end of the shaft 80. This hand wheel may be used for manually setting the control device to any desired point where the `discharge operation should -be maintained or is to be maintained if it should be desired or necessaryfto 4dispense with the automatic control forany reason.

Changes may be ma-de within the scope and spirit of the appended claims, wherein I -have defined what is believed to be new and is de- 75 sired to have protected by Letters Patent of the United States.

What is claimed is:

l. A control device for apparatus having a compartment wherein comminuted particulate material is separated in accordance with the specic gravities of its constituent parts and having an adjustable discharge valve for removing from said compartment separated material, comprising a float in said compartment which is sensitive to uctuations of the material level therein, switching means for coaction with said float, control means for adjusting said discharge valve, means for movably mounting said switching means, and operating means controlled by said switching means responsive to displacement of said float for actuating the control means for adjusting said discharge valve and for moving said switching means relative to said float so as to position said switching means for coaction with said float responsive to subsequent fluctuation of the material level in said compartment.

2. The device dened in claim 1, wherein said switching means comprises a pair of normally open contacts, actuating means for said contacts, a support for said contacts and said actuating means and mounting means for movably securing said support, together with means actuated `by said float for'operating said contact actuating means.

3. The device dened in claim l, wherein said operating means comprises a control shaft, ratchet means for rotating said shaft, electromagnetic means responsive to the operation of said switching means for actuating said ratchet means, and means governed by said shaft for actuating said control means for adjusting said discharge valve and for simultaneously moving said switchling means relative to said float.

4. The device defined in claim 1, wherein said operating means comprises a control shaft, electromagnetic means responsive to the operation of said switching means for rotating said control shaft, an operating shaft gear means between said shafts for transmitting the rotation of the control shaft to the operating shaft, and means actuated by said operating shaft for moving said switch and for adjusting said discharge valve.

5. The device deiined in claim l, wherein said operating means comprises a control shaft, electromagnetic means responsive to the operation of said switching means for rotating said control shaft, an voperating shaft, gear means disposed between said means actuated by said operating shaft for moving saidV switching and for adjusting said discharge valve, and switching means coacting with said control shaft for controlling the circuit of said electromagnetic means.

6. The device defined in claim 1, wherein said operating means comprises a control shaft, electromagnetic means responsive to the operation of said switching means for rotating said control shaft, an operating shaft, gear means disposed between said shafts, means actuated by said operating shaft for moving said switching means and for adjusting said discharge valve,normally closed contact means positioned in the cirvcuit of said electromagnetic means, and means -operated by said control shaft for actuating said contact means.

7. In a separator having a chamber wherein comminuted particulate material is separated according to the specic gravities of its constituent parts and having a pawl and ratchet operated valve for moving material relative to said chamber, a device for variably adjusting the operation of said valve to control the material level in said chamber, said device comprising a float in said chamber which is sensitive to fluctuations of the material level therein, trip means on the float stem, a switch disposed adjacent the trip means on said float stem and carrying contact actuating lever means for coaction with said trip means in either direction of motion said float and control means responsive to the actuation of said lever means for governing the position of the pawl with respect to the ratchet of said valve to adjust the discharge in accordance with fluctuations in the material level and for simultaneously moving said switch with respect to the noat stem in the direction of movement of the float to position said switch for subsequent coaction with said trip means responsive to subsequent fluctuations of the material level which causes additional displacement of said float.

8. A device for controlling the actuation of a pawl and ratchet operated discharge valve in 4a gravity separator of the class described in accordance with the fluctuations in the material level therein, comprising a movable shield arranged for coaction with the pawl to determine the position thereof with respect to said ratchet, a link for moving said shield and a crank disk for actuating said link, a rotatable operating shaft for actuating said crank disk, a rotatable control shaft, gear means between said shafts for transmitting motion from the control shaft to the operating shaft, step-by-step means adapted to rotate said control shaft in successive steps to obtain progressive angular displacement thereof in either direction of rotation, and electromagnetic means selectively governed by fluctuations in the material level in said separator for actuating said step-by-step means to rotate said operating shaft through the medium of said control shaft in a direction corresponding to the progressive iiuctuations of said material level.

9. rEhe device defined in claim 8, together with limit switch means operable by said control shaft for limiting the angular displacement thereof to predetermined points in both directions of operation.

10. A variable automatic discharge control for a separator of the class described, comprising a device for variably adjusting the discharge operation to compensate for variable uctuations of the material level in said separator, a control switch which is sensitive to such fluctuations of said material level and governs the operative actuation of said device, and means operated by said device simultaneously with adjusting the discharge operation for moving and displacing said control switch in accordance with the direction of fluctuation of said material level.

1l. The control defined in claim 10, together with a pawl and ratchet operated control shaft in said device, a pair of electromagnets controlled by said control switch for actuating said shaft, and auxiliary switching means controlled by said shaft for governing the operation of said electromagnets.

12. In a separator having a separating compartment and an adjustable valve for moving material relative thereto, a float which is sensitive to iiuctuations of the material level in said compartment, trip means moved by said float responsive to displacement thereof, a switching Cil device disposed in the path of said trip means which is actuated thereby in either direction of movement thereof, control means responsive to the actuation of said switching device for adjusting the operation of said valve, and means actuated by said control means for moving said switching device relative to said float and said trip means so as to reposition said switching device for subsequent actuation by said trip means responsive to subsequent displacement of said float.

13. The combination and structure defined in claim 12, wherein said switching device comprises a movably mounted base, a pair of contact springs on said base, a lever arm for each spring, and link means connecting said base with said control means.

14. The combination and structure defined in claim 12, wherein said switching device comprises a base adapted to be moved in a plane paralleling the plane of movement of said trip means, link means connecting said base with said control means, a contact spring adapted to be actuated by said trip means in one direction of movement thereof, a contact spring adapted to be actuated by said trip means in the other direction of movement thereof, and circuit means connecting said spring means with said control means for transmitting impulses thereto responsive to actuation thereof by said trip means.

15. rihe combination and structure defined in claim 12, wherein said switching device controls two current impulse circuits leading therefrom to said control means, one circuit being eective to transmit to said control means current impulses responsive to actuation of said switching device during movement of said trip means in one direction and the other circuit being effective to transmit impulses responsive to actuation of said switching device during movement of said trip means in the other direction, together with electromagnetic means in said control means, one for each of said impulse circuits for receiving the impulses transmitted thereover.

16. The combination and structure defined in claim 12, wherein said switching device controls two current impulse circuits leading therefrom to said control means, one circuit being effective to transmit to said control means current impulses responsive to actuation of said switching device during movement of said trip means in one direction and the other circuit being effective to transmit impulses responsive to actuation of said switching device during movement of said trip means in the other direction, together with electromagnetic means in said control means, one for each of said impulse circuits for receiving the impulses transmitted thereover, control contact means in each of said circuits, and means operated by said control means after receiving a predetermined number of successive impulses over either of said circuits for actuating the control contact means thereof.

17. The combination and structure defined in claim 12, wherein said control means comprises a rotatable control shaft, a pair of ratchets, one for rotating said shaft in either direction of rotation, an electromagnet for actuating each ratchet, and an electric circuit for each electromagnet extending to said switching device for transmitting an impulse thereover in response to actuation thereof by said trip means.

18. The combination and structure defined in claim 12, wherein said control means comprises a rotatable control-shaft, a pair of ratchets, one

for rotating said shaft in either direction of rotation, an electromagnet for actuating each ratchet, and an electric circuit for each electromagnet extending to said switching device for transmitting an impulse thereover in response to actuation thereof by said trip means, together with normally closed contact spring means in each said circuit, and means effective after transmitting a predetermined number of impulses over either of said circuits for opening the contact spring means provided therefor.

19. Control apparatus for automatically varying the operation of a material valve in a separator of the class described to compensate for fluctuations of the material level occurring during operation in the separating compartment thereof, comprising an impulse producing device, control means sensitive to fluctuations of said material level and responsive to a rise or a drop thereof for actuating said device to produce an impulse signalling such rise or drop, a pair of electromagnets for receiving such rise and drop signalling impulses, respectively, and means actuated by either of said magnets for effecting adjustment of the operation of said material valve and for moving said impulse producing device relative to said control means soY as to reposition it for subsequent actuation thereby responsive to further rise or fall of said material level.

20. The structure and combination defined in claim 19, wherein a float constitutes said control means, and wherein said impulse producing device comprises a movably mounted base, a pair of contact springs on said base, one for actuation by said iioat during the rise and one for actuation by said float during the drop of said material level, and means operable by the means actuated by said magnets for moving said base relative to said float.

2l. In combination, in a separator of the class described, a float disposed in the separating compartment of said separator and adapted to follow fluctuations of the material level therein, a pair of contact springs adapted' to be actuated by said oat during the rise or drop thereof, respectively, to produce signalsindicating such rise or drop, and means responsive to either such signal for effecting a compensating adjustment of the discharge valve of said separator and to move said contact springs relative to said float so as to reposition said springs for further actuation thereby responsive to subsequent rise or drop 0f said material level.

HARRY W. BRENTZ.

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