US2964359A

US2964359A - Feed adjusting means for hammer mills, pneumatic conveyors and the like suction-operated means

Info

Publication number: US2964359A
Application number: US538499A
Authority: US
Inventors: Abonnenc Jean
Original assignee: Individual
Current assignee: Individual
Priority date: 1954-10-15
Filing date: 1955-10-04
Publication date: 1960-12-13
Anticipated expiration: 1977-12-13
Also published as: DE1060227B

Description

"`n. 13, 1960 J, ABONENC 2,964,359

FEED ADJUSTING MEANS FOR HA MER MILLS, PNEUMATIC CONVEYORS AND THE LIKE SUCTION-OPERATED MEANS Filed Oct. 4, 1955 3 Sheets-Sheet 2 L a W57?? g ATTORNEY 5 Dec. 13, 1960 J. ABoNNr-:Nc 2,964,359 4 FEED ADJUSTING MEANS FOR HAMMER MILLS PNEUMATIC l coNvEYoRs-AND THE LIKE sucTIoN-OPERATEDMEANS Filed oct. 4. 1955 s sheets-sheet s ATTORNEY Si United States PatentfO FEED ADJUSTING MEANS FOR HAMMER MILLS,

PNEUMATIC CONVEYQRS AN D THE LIKE SUC- 'rIoN-orEnATED MEANS Jean Ahonnenc, Luc-en-Diois, France Filed oct. 4,1f955,ser.fNo. 538,499 Claims priority, application France Oct. 15, -`1954 7 claims. (ci. soz-+36) ,Percussion Crushers and hammer mills require for the removal of lthe material crushed therein a`powerful -suction adapted 'to empty theV crushing chamber and to convey the crushed material further on. `The capacity of production of such machines is highly variable. `It depends on the size of the openingsin the grids and on ythe nature of the materials to be crushed, thel said v4materials differing as to their specific weight, hardness and `contents of cellulose or the like fibres.

The maximum efli'ciency of a`crusher is reached at the thresholdof c logging. This clogging occurs when the suction is no longer `suflioient `for ,the removal and the .'co'nveyanceof the 4crushed material. When one operates beyond this threshold, in the case of an excess amount of material entering the apparatus, the suction is out oli entirely or nearly so. This ,leads to a very 4'large demand fordriving power which, in the case of a crusher controlled byan electric motor, may produce overload operation of the circuit-breaker controlling the circuit feeding the motor. It is then necessary to unclog the'crusher by hand together the suction means, before resuming operation. In practice, the attendants or lthe automatic means controlling the input of material into the Crusher operate with a high margin of safety so as to avoid Va clogging, but the yield obtained is then lower than that actually obtainable using the full efiiciency of the machine. i

` My invention hasfor its object feed-adjusting means applicable to machines operating under suction and chiey to hammer mills and pneumatic conveyors, and adapted to feed themachine in .a uniform and `constant manner at the `limit of its capacity before clogging, whatever r'may be the material to be crushed, provided it is of a pulverulent nature and capable of being conveyed pneumatically.

To this end, the material to be crushed or conveyed is fed into a rectangular opening located in a horizontal plane inside a casing out of which the said material cannot ow Y through gravity while it is sucked out of Athe saidv casing through another rectangular opening located at the same level or at a level above that of the first mentioned opening, the said two openings being 'separated from one another by a partition, so that the suction acts along a curvilinear path assuming the shape of a syphon and the lowermost point of which regis ters vertically with the said partition at the level of a line parallel to' and in proximity with the lower ridge of the said wall or partition, said line detining the llimit beyond which -the machine becomes clogged and corresponding to the maximum possible yield of the machine.

To obtain this automatic regulation of the feed of the machine for continuous operation at maximum yield, lthe ridge of the partition separating the two openings serving for the `feeding 4and the suction respectively, 4farms the control member operating through the agency of one or more level detectors. The said detectors, which may be advantageously of an electronic type,

hold the lowermost point of the suction 'curve near the threshold of Aclogging by acting on the feed of the machine, the driving motor of which remains continuously operative.

The feed of the machine may be adjusted gradually through a modification of the `cross-section lof Ithe A-passage provided for the' material vor else through a`modi- -cation of the speed of ow of said material.

Thus, in a preferred embodiment, the detector or detectors carried by the partition separating the two openings in 4the machine control the operation of an electric motor which produces, through `the agency of a worm and of a lever system, the opening or the closing of a gate inserted in the feed pipe.

Although the adjusting means, according to my invention, may include only a maximum or a minimum detector, it is preferable to provide .it with both types of detector.

'In a preferred embodiment, I may utilize to a maximum and minimum detector comprising two light beams extending 'across the syphon-shaped curve andV produced by ftwo sources of light arranged laterally atone side of the `syphon so as to impinge on corresponding photocells on the opposite `sideA of the said ysyphon, the vvertical spacing between the two sources' of light being adjustable, so as .to allow` for modification of the ditle'r ence between the maximum and the minimum permissiblelevels ofthe material. I

'ln a further embodiment, the maximum and minimum detectormaybe constituted byadetector' of the lpresence of the `material associated with a beam' produced -by `a source of light and limpinging on'a photocell, theV said detector .and saidb'eam being vertically ydim'ensioned to define, respectively the maximum limits and the minimum, or conversely.

According to a still further feature of my invention, the adjusting means includeat least one Vadditional air intake formed at a point of the flow path feeding the material'to be crushed into the input of the crusher so as to allow a suction to be exerted onthe material in the case of a temporary fortuitous clogging of the actual adjusting means. This air intake is constituted preferably by an opening formed in one or in both of the two side walls ot' the adjusting means at a level such that its center is located substantially in register with the line defining the threshold of clogging.

The additional air intake may also be formed by an elongated slot in the wall of the adjusting means on the downstream side of the syphon or else, by a channel opening ahead of and 'underneath the partition separating the two openings corresponding respectively to the admission and to the suction of the material through the adjusting means while a ap engaging the said channel allows adjusting not only the flow rate of the additional air but also the average ow rate through the machine.

Such additional air 4intakes may be used either alone .or in combination with a further additional air intake 'formed in the wall of the adjusting means on the downstream side of the suction opening.

This latter air intake may extend throughout the breadth 'of the adjusting means and may preferably take the form ofi an auxiliary syphon provided with a ap which allows adjusting the input of air while the material which may drop out fortuitously during the suction stage into the air intake, collects at the bottom `of the said auxiliary syphon.

1 have illustrated diagrammatically by way of example in accompanying drawings various embodiments of my improved arrangement. In said drawings:

Figs. 1 and 2 are respectively front and side elevational partly sectional views of a crusher provided with a lateral input and with the above referred to adjusting means;

Fig. 3 is a longitudinal sectional view of a pneumatic conveyor provided with similar adjusting means;

Fig. 4 is a perspective view of the simplest embodiment after removal of one of the side walls of the spyhon;

Fig. 5 shows on an enlarged scale the same embodiment in longitudinal cross-sectional view;

Fig. 6 is a general perspective view of the means for adjusting the fiow rate;

Fig. 7 is a diagram showing the possible modifications of the curve defining the air passage;

Figs. 8 and 9 show two detectors for sensing the presence ofthe material in the syphon;

Figs. 10 and 11 show two maximum or minimum detectors utilizing a photocell;

Figs. l2, 13, 14 show three different forms of maximum and minimum detectors;

Figs. 15 and 16 are longitudinal sectional views of two alternative improved embodiments of the adjusting means.

Figs. l and 2 illustrate a crusher having a lateral input of a conventional type and with which the adjusting means according to my invention have been incorporated.

In said gnres, 70 designates the body of the crusher, 71 the crushing chamber inside which the hammers 72 rotate, said hammers being carried by a shaft 73 adapted to revolve at a high speed.

74 designates the grate closing the crushing chamber at its lower end, and through which the crushed material drops onto a sloping surface 75 ofi' which it is sucked through a suction opening 76 into a shell 77 under the action of the bladed rotor 78 of a suction device, while 79 designates an additional air intake through which it is possible to sweep the material ot the grate of the crusher.

The feeding of said crusher is performed through a hopper 80 located above it and the lower end of which is provided with a distributor 81 including a gate 82 controlled by a lever 83 actuated through a nut 84 adapted to move vertically over a threaded member 85 driven into rotation bv a motor and speed reducing group 86. 87a and 87b designate two stops defining the stroke of the nut 84 and consequently that of the gate 82.

4The adjusting means forming the object of mv invention are inserted between the distributor 81 and the upper section of the casing of the crusher 70.

Said adiustinr means are constituted as illustrated in Figs. 4 and 5 bv a casing 2 formed by walls defining with one another three openings, to wit:

A first opening A of a rectangular shape located in a horizontal plane, which opening serves as an inlet for the feeding of the material into the arrangement;

A second opening B of a rectangular cross-section having the same size as the opening A and located in a horizontal plane coplanar with the first mentioned plane of the opening A or lying in proximity with the latter and separated from the said first opening A by the ridge C-D forming the lower edge of the downwardv concavely curved partition 2 defining the upper surface of the suction channel, the said opening B being the suction opening;

A third opening C of a rectangular cross-section located in a horizontal plane and separated from the second opening bv the ridge G-H forming the unper edge of the upright partition 63. the said third opening providing for the delivery of the pulverulent material down- Wardlv into the crusher or the like machine (see Figs. 1 and 2);

These three openings A, B, and C lying in horizontal planes are defined in practice and as apparent from the drawing, by the gaps between the downwardly concave partition 2, the rear wall of the casing and the front wall or partition 63 thereof.

The arrangement of the horizontal planes provided with the openings A, B and C associated with the bottom 5, with the curved wall 2 and with the vertical partition 63 terminating with the ridge G-H, defines the syphon forming the adjusting means.

When the material to be crushed enters the regulator as illustrated by the arrow 1 shown in Fig. 1, it passes through the feed opening A and drops into the bottom 5 of the casing and it is then sucked through the opening B in the direction of the arrow 6 of Fig. 1. The path followed by the upper surface of the material inside the adjusting means crosses consequently the vertical plane extending perpendicularly to the openings A and B between the latter and through the ridge C-D. The line E-F shows the intersection between the said path and the said vertical plane, said line E-F being parallel with the ridge C-D.

If the flow rate of the material conveyed is low with reference to the capacity of the machine, the line E-F sinks away from the ridge C-D. If the ow rate increases, the line E-F rises towards the said ridge C-D. If the ow rate is too high, the said line E-F coincides with the ridge C-D. This leads to a clogging of the arrangement as a consequence of the complete closing of the gap through which the material is sucked in, as defined by the four-sided polygon C--D-F-E.

It should be remarked that, when the ow rate increases, i.e. when the line E-F rises towards the ridge C-D, there is a moment at which the arrangement is on the threshold of clogging. The line E-F registers then with a limit line which is designated in Fig. 1 by X-Y. The said line defines with the ridge C-D the normal suction gap ensuring maximum efficiency of the machine.

The adjusting means described are such that the lowermost point of the curve followed by the material is permanently tangent to the said line XY, said means i11- cluding to this end a detector of levels located on the said line so as to allow adjusting accurately the flow rate through the machine by constraining the line E-F to coincide with the line XY. This provides for maximum efiiciency without any risk of clogging.

The level detector may be a detector of the photocell type or an electronic presence detector. The said detector may act, as shown in Fig. 6, on an electric motor 8 adapted to revolve in both directions and which, when started, drive a worm 9 which produces a translational shifting of a nut operatively associated with a lever 12 pivoted at 13 so as to produce, according to its direction of movement, the opening or the closing of a gate 14 located at the end of the channel 15 opening above the feed-adjusting means. Switches 16 and 17 controlled at the ends of the strokes of the unit in either direction produce a stopping of the motor in correspondence with the closing and with the opening of the gate 14 respectively and they ensure simultaneously the desired safety by showing acoustically and/or optically that the feeding silo or the like is empty while the gate remains open, or reversely, that the adjusting means are still clogged While the gate remains closed.

It should be remarked that, in order to prevent any too sudden or frequent reversal of the motor controlling the feed of the adjusting means, which would lead to a constant beating of the adjusting gate 14, it is possible to provide maximum and minimum detectors which allow stabilizing, as illustrated in Fig. 7, the fiow rate to either side of the line X--Y between two lines corresponding to the allowed maximum and minimum rates.

The presence detectors 21 illustrated in Figs. 8 and 9 are adapted to act on the feeding of the machine accord'- ing as to whether they are covered or not by the material Ato be conveyed. The said detectors 21 are located at an adjustable height inside the syphon 22 so that the maximum or minimum defined by the said detector may be modified as desired.

In the case illustrated in Fig. 10, the maximum or minimum detector is constituted by the combination o-f the source of light 23 with the photo-cell 24; the said source and photo-cell are arranged to either side of the body 25 of the syphon and the luminous Vbeam produced by the projectors 23 impresses the cell-24 across thefs'aid t syphon, the two walls of which Vare provided with openings 26 facing each other.` According as to whether the beam of light 28 from the projector'23 is cut ofi or not by the material 29 inside the syphon,` and consequently, according as to whether the cell 24 is illuminated or' not, the said cell will act on the feeding of material into the syphon so as to reduce the throughput if the detector is a maximum detector or to increase the flow rate if the detector is a minimumdetector.

When adjusting the maximum or the minimum, it is suiiicient to shift the projector 23 in the direction of the arrow 311 of Fig. lO, the transparent plates 27 allowing a slight shifting of the luminous beam.

In the case of the modification illustrated in Fig. l1, the adjustment of the maximum or of the minimum is obtained through a modification of the angular position of the projector 23 and consequently through a modification of the angular setting of the beam of light.

A maximum and minimum detector may be constituted, as illustrated in Fig. Vl2, by two sets of projectors and photo-cells. The two projectors 32a and 32h are located above each other at different levels on the right hand side and on the left hand side of the syphon respectively, so

as to produce luminous beams 33a and 33b adapted to impress the two cells 34a and 34b registering with the said projectors and also located at different levels. The cell 34a controls the reduction in the ow rate at the input end whenever the beam 33a is cut off by the material inside the syphon 35. The cell 34h controls, in contradistinction, the increase of the flow rate `at said input end whenever the beam 34h is no longer cut off by the said material. The level of the material 36 inside kthe syphon is thus constrained to move within narrow limits to either side of the dot-and-dash line x-y.

The adjustment of the average fiow rate to either side of the said line x-y may be obtained by modifying the location of the projectors 32a, 3-2b the level of which may be adjusted with reference to that of the corresponding photo-cells 34a, 34h.

In the case where the products to be sucked out form a very irregular sheet or in the case of a machine having a very large cross-section, it is possible to reso-rt to the maximum and minimum detector system illustrated in Fig. 13. The two projectors 37a and 37b are located in the central part of the syphon, above each other, while the beams produced by them as shown at 38a and 38b are adapted to impinge on the corresponding photo-cells 39a and 3911 located to either side of the syphon 41, the cell 39a defining the maximum flow rate, the cell 39b defining the minimum flow rate.

The adjustment is performed as precedingly through a shifting of the projectors 37a and 37b which are both housed inside a common casing'42.

Obviously, only one of the projectors may be located at the center of the syphon, the other being located laterally as illustrated in dotted lines in Fig. 10, or else the two projectors may be located on the outside of the syphon and the two cells inside the central casing 42.

As to the maximum and minimum detector illustrated in Fig. 14, it is constituted by a member 43 subjected to modifications in capacity and deiining the maximum flow rate, the said member being associated with a projector Obviously, the reverse solution is possible, in other Words,

agees-5,@

d the. minimum may be deteotedby the member subjected to modilications in capacity ywhile' the maximum is detected'by the luminous beam.

As illustrated in the drawings, the lateral openings 26 of the syphon are not closed, although they may be closed by transparent plates. These openings serve, as a' matter of fact, not only for the passage of the luminous beams adapted to detect the maximum and the minimum, but also They allow cleaning the lenses of the projector, which prevents any dust deposit from forming and thus giving erroneous results in the detection, since the suction produced in the syphon does not allow the material to escape through the openings 26 and the stream of air produced in the vicinity of the said openings ensures a permanent cleaning of the lenses;

The said openings form additional intakes which allow, in `the case of a fortuitous clogging of the syphon, an automatic release of the said clogging; to this end, the centers of the two openings 26 which are coaxial, lie substantially at the level of the line x-y corresponding to the limit of clogging.

The two additional air intakes thus formed are advantageously completed by a further air intake formed by a slot S4 provided in the wall 50 of the syphon (Fig. l5).

However, in order to prevent on the one hand any introduction of foreign material inside the regulator through the channel 53 and on the other hand any passage of the material undergoing treatment through the said additional air intake or slot 54, which passage may occur fortuitously either because the material subjected to suction follows the curved wall 50 or else, because in a hammer m-ill, the crushed material may be projected in the direction of the arrow 55, I resort preferably to the arrangement illustrated in Fig. 16.

The wall 52 of the channel 53 lying ahead of the in curved wall 50 has in this case at its upper end an incurved section 56 forming a reversed syphon associated with a plate 57 the position of which may be adjusted through the levers 58 so as to modify the amount ofair entering through said additional air intake.

Furthermore, at the level of the slot or additional air intake 54a, the wall 50 of the adjusting means carries downwardly curved plate 59 extending above a trough 61 inside which may collect any material projecting outside the main syphon underneath the Wall S0. This trough 6l may be adjusted as to position through a lever 62 so as to allow regulating the amount of additional air entering the adjusting means.

A further additional air intake may be constituted, as illustrated in Figs. 15 and 16, by a transverse partition 52 arranged vertically and the lower ridge of which extends downwardly into the opening A defining the input of material and is located at a level lower than that of the lower ridge of the wall 50. The two Walls 52 and Si) form together a vertical channel '53 extending transversely throughout the breadth of the arrangement so as to form this further additional air intake.

It is apparent that when the level of material inside the adjusting device reaches the lower ridge of the wall 52 and the machine is clogged, the air sucked in through the lchannel 53 allows a speedy` release of the said clogging.

The adjustment of these different additional air intakes allows modifying simultaneously the average throughput of the arrangement. As a matter of fact, if, during nor'- mal operation, the average level of the material lies on the line defined by the cross shown in Fig. 16, and, if the additional air intake is throttled without any reduction in the amount of material fed into the arrangement, the level vof the material inside lthe latter drops. For restoring the level, it is, consequently, necessary to increase the ow rate.

ape-gasa Reversely, if the additional air intake is opened to a wider extent without any modification of the feed, the level of the material inside the arrangement rises. It is, therefore, necessary to reduce the flow rate of material so as to restore the level to the desired value.

The closing and the opening of the additional air intake may be controlled from a distance by an auxiliary motor and by a worm or else, through any other suitable mechanical means.

The arrangement described may also show the following auxiliary features:

It includes at least in one of its side walls an inspection gate 18 (Figs. 4 and 7),V wherethrough it is possible to inspect the level of the material and also to make sure that no foreign body shown at 19 and collecting at the bottom of the syphon formed by the ridge C-D reaches a level corresponding to the clogging area. The removable bottom of the casing allows also emptying the latter from time to time so as to remove such foreign bodies at 19;

The wall 63 the upper edge of which forms the ridge G-H separating the two openings B and C, may be adjustable and the same is the case for the upper incurved wall 2 guiding the material through the syphon. As a matter of fact, as illustrated in Figs. 4 and 5, the said wall 63 may be vertically slidable inside the regulator and the upper wall 2 may be pivotally secured along a horizontal line 64. It is thus possible to shift the ridges C-D and G-H. These adjustments allow modifying the curve followed by the material entering the feedadjusting means. By lowering the wall 63 with the ridge G-H or by raising the Wall 2 with the ridge C-D, the entrance of heavy material inside the regulator is made easier. Obviously, however, the input curve for the material should not be such as might allow the latter to enter through mere gravity, since the syphon would no longer act as a clogging-limiting member and as a member preventing the entrance of foreign bodies;

To allow the material entering the adjusting means to be subjected to suction while it assumes the shape of a uniform layer, it is of advantage to provide in proximity with the bottom of the adjusting means and underneath the admission opening A a rotary member which ensures a suitable distribution of the material. Thus, the material reaches the adjusting means and consequently the crusher, as a layer of a uniform thickness and of a breadth corresponding to that of the input end of the crusher. Such a distribution is, furthermore, of considerable advantage for ensuring maximum eiciency for the crusher.

As stated hereinabove, the feed adjusting means according to my invention are adapted for use not only on hammer actuated crushers but with all suction means such as chiey pneumatic conveyors.

Such feed adjusting means are, in fact, shown in the case of the -application illustrated in Fig. 3, where 89 designates such a pneumatic conveyor pipe, in which the suction is exerted in the direction of the arrow 91. 92 designates a gate closing normally the conveyor pipe 89 ahead 4of the lateral opening 93 to the periphery of which are secured the adjusting means. 94 designates a cover which normally leaves the opening 93 uncovered but allows if required closing the latter if the pipe 89 is to convey a product fed from a supply ahead of the gate 92.

What I claim is:

1. An adjustable syphon controlling the flow of granular material, comprising a channel having an upper arcuate downwardly facing concave wall, means for feeding the granular material into one end of the channel longitudinally of the latter along lines extending in vertical planes round the lower edge of the corresponding end of said upper wall to urge said material through the channel, suction means adapted to draw the granular material out of the other end of said channel, the suction line defined by the upper surface of the material flowing through the channel following an incurved path the concavity of which is directed downwardly and the lowermost point of which at the first-mentioned end of the channel registers vertically with .the lower edge of the upper wall of the channel at said first-mentioned end of the channel, at least one detector sensitive to the level of said lowermost point of the suction line with reference to a transverse horizontal line passing along said lower edge of the upper wall of the channel and means wherethrough said detector controls the flow of material through the material-feeding means to return the level of said lowermost point of the suction line into substantial coincidence with a predetermined position with reference to said transverse line.

2. An adjustable syphon controlling the ow of granular material, comprising a channel having an upper arcuate downwardly facing concave wall, means for feeding the granular material into one end of the channel longitudinally of the latter along lines extending in vertical planes round the lower edge of the corresponding end of said upper wall to urge said material through the channel, suction means adapted to draw the granular material out of the other end of said channel, the suction line defined by the upper surface of the material flowing through the channel following an incurved path the concavity of which is directed downwardly and the lowermost point of which at the first-mentioned end of the channel registers vertically with the lower edge of the upper wall of the channel at said first-mentioned end of the channel, at least one detector sensitive to the level of said lowermost point of the suction line with reference to a transverse horizontal line passing along said lower edge of the upper wall of the channel, an electric motor controlled by said detector and a gate controlled by said motor and controlling the flow of material into the material feeding means in accordance with the shifting of said level of the lowermost point of the suction line with reference to said transverse line.

3. An adjustable syphon controlling the flow of granular material, comprising a channel having an upper arcuate downwardly facing concave wall, means for feeding the granular material into one end of the channel longitudinally of the latter along lines extending in vertical planes round the lower edge of the corresponding end of said upper wall to urge said material through the channel, suction means adapted to draw the granular material out of the other end of said channel, the suction line defined by the upper surface of the material flowing through the channel following an incurved path the concavity of which is directed downwardly and the lowermost point of which at the first-mentioned end of the channel registers vertically with the lower edge of the upper wall of the channel at said first-mentioned end of the channel, two sources of light arranged to either side of the path followed by the material near the said lowermost point of the suction line, photo-cells located to either side of said path and subjected to the impact of the luminous beams produced by the sources of light, means for adjusting the relative position of the associated photo-cell and source systems, means whereby the photocells detect the rising and lowering respectively of the lowermost point of the suction line with reference to a predetermined line parallel with a horizontal transverse line passing along said lower edge of the upper wall of the channel, and means controlled by the photo-cells to control the ow of material through the material-feeding means and to return thereby the said lowermost point of the suction line towards the said predetermined line.

4. An adjustable syphon controlling the flow of granular material, comprising a channel having an upper arcuate downwardly facing concave wall, means for feeding the granular material into one end of the channel longitudinally of the latter along lines extending in vertical planes round the lower edge of the corresponding end of said upper wall to urge sa'd material through the channel, suction means adapted to draw the granular material out of the Aother end of said channel, the suc- Q tion line defined by the upper surface of the material wing through the channel following an incurved path the concavity of which is directed downwardly and the lowermost point of which at the first-mentioned end of the channel registers vertically with the lower edge of the upper wall of the channel at said first-mentioned end of the channel, a detector of the presence of material, a

photocell, a source of light producing a beam impinging on the photo-cell, said detector and photo-cell being adapted to detect respectively one of the extreme allowed shiftings of the lowermost point of the suction line to either side of a predetermined line parallel with a horizontal transverse line passing through said lower edge of the upper wall of the channel, and means whereby said detector and photo-cell adjust the flow of material through the material feeding means to urge said lowermost point into register with the said predetermined line.

5. An adjustable syphon controlling the flow of granular material, comprising a channel having an upper arcu ate downwardly facing concave wall, means for feeding the granular material into one end of the channel longitudinally of the latter along lines extending in vertical planes round th'e lower edge of the corresponding end of said upper wall to urge said material through the channel, suction means adapted to draw the granular material out of the other end of said channel, the suction line defined by the upper surface of the material flowing through the channel following an incurved path the concavity of which is directed downwardly and the lowermost point of which at the first-mentioned end of the channel registered vertically with the lower edge of the upper wall of the channel at said first-mentioned end of the channel, at least one detector sensitive to the level of the lowermost point of the suction line with reference to a predetermined line parallel with a horizontal transverse line passing through said lower edge of the upper wall of the channel and at a short distance underneath last-mentioned edge, an auxiliary air intake opening into said channel, the center of which intake registers substantially with said predetermined line to provide for further suction on the material, and means wherethrough said detector controls the flow of material through the material feeding means to return the lever of said lowermost point of the suction line into substantial coincidence with said predetermined line.

6. An adjustable syphon controlling the ow of granular material, comprising a channel having an upper arcuate downwardly facing concave wall, means for feeding the granular material into one end of the channel longitudinally of the latter along lines extending in vertical planes round the lower edge of the corresponding end of said upper wall to urge said material through the channel, suction means adapted to draw the granular material out of the other end of said channel, the suction line dened by the upper surface of the material llowing through the channel following an incurved path the con cavity of which is directed downwardly and the lowermost point of which at the first-mentioned end of the channel registers vertically with the lower edge of the upper wall of the channel at said rstr-mentioned end of the channel, an elongated slot being provided across the upper wall of the channel just ahead of its lower edge at said other end and adapted to provide a further suction on the material ilowing through the channel, an adjustable flap controlling the amount of air passing through said elongated slot, means for collecting the material passing fortuitou-sly out through said slot, at least one detector sensitive to the level of said lowermost point of the suction line with reference to a transverse horizontal line passing along said lower edge of the upper wall of the channel, and means wherethrough said detector controls the flow of material through the material-feeding means to return the level of said lowermost point of the suction line into substantial coincidence with a predetermined position with reference to said transverse line.

7. An adjustable syphon controlling the ow of granular material, comprising a channel having an upper arcuate downwardly facing concave wall, means for feeding the granular material into one end of the channel longitudinally of the latter along lines extending in vertical planes round the lower edge of the corresponding end of said upper wall to urge said material through the channel, suction means adapted to draw the granular material out of the other end of said channel, the suction line defined by the upper surface of the material flowing through the channel following an incurved path the concavity of which is directed downwardly and the lowermost point of which at the first-mentioned end of the channel registers vertically with the lower edge of the upper wall of the channel at said first-mentioned end of the channel, an inspection gate opening into the channel, a removable bottom through which foreign material may be removed out of the channel, at least one detector sensitive to the level of said lowermost point of the suction line with reference to a transverse horizontal line passing along said lower edge of the upper wall of the channel, and means wherethrough said detector controls the flow of material through the materialfeeding means to return the level of said lowermost point of the suction line into substantial coincidence with a predetermined position with reference to said transverse line.

References Cited in the file of this patent UNITED STATES PATENTS 1,191,072 Fessenden July 11, 1916 1,755,490 Seymour Apr. 22, 1930 2,668,365. Hogin Feb. 9, 1954 2,774,637 Sylvest Dec. 18, 1956