WO2001045846A1

WO2001045846A1 - Rotor with guide with inclined feed edge

Info

Publication number: WO2001045846A1
Application number: PCT/NL2000/000939
Authority: WO
Inventors: Johannes Petrus Andreas Josephus Van Der Zanden
Original assignee: Van Der Zanden, Rosemarie, Johanna
Priority date: 1999-12-20
Filing date: 2000-12-19
Publication date: 2001-06-28
Also published as: AU3244501A; NL1013895C1

Abstract

The invention described here relates to a rotor (1) which rotates about a vertical axis of rotation and can be arranged in a comminution device, for example a breaker or a mill, but can also be arranged in a distribution or spreader device. The rotor is provided with a central section (3) and at least one guide member (8) that is arranged on the bearing surface of said rotor and is provided with a guide surface (11) that extends from the feed edge (12) of said guide member towards the outer edge (16) of the rotor. The feed edge (12), which is some distance away from said axis of rotation (0) and forms the front edge of the guide surface (11) of the guide member, does not run parallel to said axis of rotation (0) and is oriented obliquely downwards, such that the top point (19) of said feed edge (12), where the feed edge (12) and the bottom edge (17) of the guide member intersect one another, is located a greater radial distance away from said axis of rotation (0) than is the top point (19) where said feed edge and said top edge of said guide member intersect one another. What is achieved by this means is that the metered material is better picked up by the guide member, as a result of which the capacity of the rotor increases.

Description

ROTOR WITH GUIDE WITH INCLINED FEED EDGE

FIELD OF THE INVENTION

The invention relates to the field of the acceleration of a stream of granular or particulate mateπal. with the aid of centrifugal force, with, in particular, the aim of causing the grains or particles to collide at such a speed that they break

According to a known technique the movement of a stream of material can be accelerated with the aid of centrifugal force With this technique the material is metered onto the central section of a rotor and is then picked up, from the edge of said central section, by one or more guide members which are arranged around said central section and are supported by said rotor The material is accelerated along the guide members, under the influence of centrifugal forces, and propelled outwards at high speed and at a certain angle of flight Viewed from the stationary position and when the influence of air resistance and air movements are disregarded, the mateπal moves at \ irtually constant absolute speed along a virtually straight stream after it has left the guide member, which stream is directed forwards, viewed in the direction of rotation Viewed from a standpoint moving with the rotor, the material moves in a spiral stream after it leaves the guide member, which spiral stream is oriented backwards, viewed in the direction of rotation, the relative speed increasing as the mateπal moves further away from the axis of rotation The material can be propelled outwards in this way, with the aim of distributing or spreading it evenly, for example salt on a road or seed over agπcultural land

The material can also be collected by a stationary impact member that is arranged m the straight stream which the material describes, with the aim of causing the material to break during impact The stationary impact member can be formed, for example, by an armoured ring which is arranged around the rotor It is also possible to allow material to impinge on a bed of the same mateπal

Instead of allowing the material to impinge directly on a stationary impact member, or before distributing or spreading the material, it is also possible first to allov\ the matenal to collide with an impact member that is rotating with the guide member and is rotating at the same speed, in the same direction and around the same axis of rotation, but at a greater radial distance from said axis of rotation than said guide member, and is arranged transverseh in the spiral stream which the material descπbes, with the aim of comminuting the grains

BACKGROUND TO THE INVENTION

The invention described here relates to a rotor which rotates about a vertical and can be arranged in a comminution device, for example a breaker or a mill, but can also be arranged in a distπbutor or spreader device The rotor is provided with a central section and at least one guide member that is arranged around said central section and is provided with a guide surface which extends, from the edge of said central section, towards the outer edge of the rotor, which guide surface is of essentially straight construction in the vertical direction and in the hoπzontal direction is divided into, successively, a feed edge, a feed surface, a guide surface, a dispensmg surface and a discharge edge, viewed from said axis of rotation, for, respectively, distributing, feeding (picking up), guiding, accelerating and dispensing mateπal that is metered onto the central section with the aid of a metenng member The mateπal has to pass over the feed edge in order to be picked up by the guide surface and has to pass over the discharge edge in order to leave said surface The top edge of the guide member is usually horizontal, whilst the bottom edge adjoins the rotor blade The rotor can be open, the guide and impact members being arranged on the rotor blade A rotor of this type is disclosed in US 3 955 767 The guide members can also be arranged between two rotor blades, the top edge adjoining the top rotor blade A rotor of this type is disclosed in US 4 166 585 The rotor can also be equipped with co-rotating impact members which are arranged behind the guide members, \ lewed m the direction of rotation and at a greater radial distance from the axis of rotation than the guide members A rotor of this type is disclosed in US 5 860 605 which has been drawn up in the name of the Applicant

The feed edges of the guide members of the known rotors, which form the front edge over which the material is fed to the guide member, are normally straight and arranged verticalh US 315 716, US 1 608 717 and US 3 174 697 disclose rotors which are constructed with guide members which have a front edge oriented obliquely downwards BS 376760 and Patentschπft 688169 (Reichs Patentamt) disclose rotors which are equipped with guide members that are arranged at an incline on the rotor and are constructed with a feed edge that bends inwards What is striking is that the majoπty of known rotors are equipped with a central section in the form of an upright cone

The known rotors have the advantage that the material is effectively accelerated and propelled outwards when it has been picked up by the guide members, it being possible accurately to control the speed with the aid of the speed of revolution Furthermore, the construction is simple and both small and relatively large quantities of granular matenal having dimensions which range from less than 1 mm to more than 100 mm can be accelerated

In addition to these and other advantages, the known rotors also ha\ e disadvantages For instance, the movement of some of the grains on the rotor can be disturbed, which takes place m particular when the grains are metered onto the central section of the rotor and when the grains are fed to the guide member from said central section The gram movement is translated from the vertical to the horizontal direction durmg metenng onto the central section of the rotor The movement of the material is decelerated as a result, as a consequence of which the material is able to infiltrate less far into the space between the guide members before it is picked up b\ the feed surface of a passing guide member In order to be able to be picked up from the central section by the guide members, the grains must pass the rapidh rotating feed edges of the guide members The rapidh rotating feed edges, which constitute the front edges of the guide members, form, as it were, a "rotaπ metering screen" around the central section that becomes denser - and therefore more difficult to pass through or more difficult to infiltrate - the greater the speed at which the rotor rotates and the more guide members are arranged around the central section When the rotational velocity is increased the metering screen finally becomes so dense that all grains are repulsed and therefore are no longer able to move outwards The rotor then becomes completely blocked or clogged The functioning of the rotor is thus detennined by the rotational velocity on the one hand and by the number of guide members on the other hand

However, even if the rotational \ elocity and the number of guide members are restπcted. so that the metenng screen is sufficienth open to allow the stream to pass through, it is unavoidable that some of the grains come into contact w ith the feed edges while passing through said metering screen, as a result of which the movement can be disturbed During this disturbed movement the grains can be repulsed towards the central section but can also be repulsed in an outward direction, which grains are able to move outwards between the guide members without coming into contact with said guide members and consequently leave the rotor at a different (lower) speed and along a different path compared with the grains that are picked up by the guide members Furthermore, coarser grains have to travel over a longer path than finer grains in order to pass through the distribution screen, coarser granular material is therefore more susceptible to disturbance Moreover, disturbed grains can disrupt the movement of the grams ahead} guided towards the outside

The degree to which the moλ ement of the grains is disturbed during the collision with the feed edges is determined by, on the one hand, the speed (of rotation) of the feed edges, with the consequence that said feed edges have to be arranged not too far from the axis of rotation because otherwise the speed at which the feed edges rotate becomes too high to enable the grains to be picked up, the movement of these grains is then disturbed The speed at which problems can occur increases with the grain size and is also dependent on the elasticity of the granular material, however, usually feed edge speeds higher than 10 - 20 m/s must be avoided The maximum diameter of the central section is limited as a result, this maximum diameter is determined by the angular speed of the rotor For example, at a speed of revolution of 1,000 rpm the speed of the feed edges (or the distnbution screen) is 10 m/ s a radial distance of 100 mm

from the axis of rotation On the other hand, the movement of the grains is influenced by the distance between the successn e feed edges, or the time interval at which the feed edges pass a specific point on the circle that thev describe (metering screen), viewed from a stationary standpomt An mcrease in the (angular) rotational \ elocity therefore restricts not only the diameter of the central section but also the number of guide members that can be arranged around the central section Coarser granular material also restricts the number of guide members because, as has been stated, more guide members restπct the permeability of the metering screen However, the consequence of fewer guide members is that these wear more rapidly, as a result of which the life of the rotor is limited

Moreover, air movements are generated by the rotation of the rotor, as a result of which a co- rotating bed of air forms along and around the rotor, which bed of air has a reduced pressure at the location of the central section and an excess pressure around the rotor, which initiates further circulation of air Bnnging the air into motion - the rotor essentially acts as an air pump - demands a great deal of energy, the energy consumption is deteπmned by the number, the length and m particular the height of the guide surfaces A sort of vortex is produced at the location of the central section of the rotor, as a result of which the grains are sucked inwards if they are metered from above onto the central section with the aid of a metenng member However, when they are metered, grains can come into contact with said rotating bed of air or with the feed edges, as a result of which the movement of the grains can be disturbed in such a way that the are sucked outwards agam in order then to "float" outwards (under the influence of the centrifugal force) over said rotating bed of air, that is to say over the top of the rotor Especially grains which are located along the edge (outside) of the metered stream of mateπal can have their movement disturbed in this way The maximum quantity of grains which can be picked up from the central section by a guide member at a certain rotational velocity is determined by the height of the guide member, or, to put it more accurately, the length of the feed edge However, not only the capacity but also the quantity of air that has to be displaced increases with the height of the guide members, which can lead to further disturbance of the movement of the grains, whilst much more energy' is consumed

AIM OF THE INVENTION

The aim of the mvention is. therefore, to provide a rotor which does not have these disadvantages or at least displays these disadvantages to a lesser extent, in particular a rotor with which the matenal is metered onto the central section freer from disturbance and is then picked up from the central section by the guide members freer from disturbance, whilst the quantity of air that has to be displaced is limited In addition to acceleration of the material that is freer from disturbance, the rotor of the mvention enables a larger capacity, while energy is saved

SUMMARY OF THE INVENTION -

According to the invention said aim is achieved by constructing the guide members with a feed edge that is oriented obliquely downwards, such that the bottom point of said feed edge, v\here the feed edge and the bottom edge of the guide member meet, is a greater radial distance away from said axis of rotation than is the top point of said feed edge where said feed edge and the top edge of said guide member meet The radial distance from the axis of rotation to the bottom point of the feed edge is preferably approximately 25 - 50% (depending on the height of the guide surface) greater than the corresponding radial distance to the top point of the feed edge, so that the diameter of the central section is approximately twice as large as the diameter at the top of the rotor As a result the metenng screen assumes the shape of a "bowl" that widens toyvards the bottom (which is clearly discernible when the rotor rotates rapidly), in yvhich the mateπal is better picked up, the closed shape prevents grains from being able to escape towards the top (upyy ards) if they collide yvith the feed edge Guide members which have feed edges arranged perpendicularly do not offer this protection In the case of feed edges oriented towards the rear, an open system is produced from which grains can very' easih be ejected to the outside The feed edge onented obliquely downwards can be straight but can also be curved inwards or outwards, in which case said feed edge is curved such that on every hoπzontal plane between the top edge and the bottom edge of the guide member every point on said feed edge is located a radial distance from said axis of rotation that is at least as great as the corresponding radial distance to the pomt where the line between said bottom point and said top point of said feed edge intersects said hoπzontal plane Grains must be prevented from being able to become stuck between the feed edge and the rotor blade At the point where the feed edge ad|oms the rotor blade the feed edge must therefore make an angle of at least 90°, I e a πght angle or obtuse angle, viewed from the axis of rotation, with said rotor blade

The mvention further provides a possibility for a splash member to be arranged behind each guide member, viewed in the direction of rotation, yvhich splash member is provided with a splash surface with a start edge and an end edge, which splash surface extends from said start edge towards said outer edge of said rotor, which start edge is in a location in the region behind said feed edge, viewed m the direction of rotation, and, in each hoπzontal plane bety een the highest and the lowest point of said feed edge, at a radial distance from said axis of rotation that is at least as great as the corresponding radial distance to said feed edge, which end edge is located behind the radial line which has the point where said start edge is located thereon, viewed in the direction of rotation, the top edge of which splash member is located in the same plane as the top edge of said guide member, whilst the bottom edge adjoins said rotor blade, which splash surface is so shaped and positioned that m every honzontal plane between the bottom edge and the top edge essentially every lme along said splash surface between the start edge and oriented transversely to said horizontal plane, the end edge at every point describes an angle (α') that is greater than 90° with the radial line thatjoins said pomt to the axis of rotation, viewed from said axis of rotation The splash member is preferably so arranged that the start edge is essentially coincident y ith, or adjoins, the feed edge The splash surface can be either straight or curved in the horizontal direction It is also preferable that at the location yvhere the feed edge adjoins the rotor blade said feed edge, just like the feed edge, makes an angle (γ) of at least 90°, viewed from said axis of rotation, yvith said rotor blade

The central section is preferably constructed with a horizontal central surface, which central surface extends all round towards said outer edge of said rotor, at least as far as a radial distance from said axis of rotation that is equal to the corresponding radial distance to said discharge edge The invention also provides a possibility for the rotor to be of symmetncal construction, or with guide members by means of which it is possible to guide the material outwards along both sides, or at least two sides, so that the rotor is operational in both rotational directions This is achieved, for example, by arranging the guide members tvyo-by-two and back-to-back with the discharge edges agamst each other, a splash member being arranged between the feed edges, the ends of which splash member are preferably coincident with the respective feed edges The splash member can be equipped with a splash surface that is essentially straight m the horizontal direction, but also with a splash surface that is symmetπcally curved in the direction of the coincident discharge edges An essentially equilateral triangle is thus produced as a whole If one of the feed edges is arranged along the edge of the central section, the other feed edge is a greater distance from the axis of rotation than the edge of the central section By constructing the symmetrical guide member such that it can hinge, with the hinge point located within the equilateral tπ angle at a point on the radial line from the axis of rotation which has the point where the back edges of the discharge edges touch one another located thereon, the symmetncal guide member can easily be reversed when the rotor is rotating in the opposite direction, the splash screen functioning in essentially the same way in both rotational directions Finally, the invention provides a possibility for a cover cap to be fitted on top over the guides, which cover cap extends from a distance from the axis of rotation in the region of the start pomts of the top edges of the guides towards the outer edge of the rotor

The rotor according to the invention has a number of advantages The material is metered from above with the aid of a metenng member, usually in the form of a pipe or chute, onto the central section of the rotor If the metering is studied in slow motion (3,000 images per second) with the aid of a high speed video camera a sort of pillar-shaped stream of granular material is detected, which, as it were, "stands" on the central section and "sloyy ly" slumps, this pillar widening towards the bottom - forming a sort of upright cone - and penetrating into the space between the guide members The movement of the grains (or the pillar) is essentially not affected by the rapidly rotating central surface on which the column "stands" Widening of the pillar therefore takes place all round virtually entirely in the radial direction This behay lour does not change substantially if the central surface is constructed in the form of an upright cone instead of flat (horizontal) In the case of a flat central section the centre (middle) of the pillar acts as a sort of natural cone It is therefore preferable to make the central section flat, or with a horizontal central surface, said central surface extending to at least the discharge edges of the guide members A cone-shaped central section does not contribute substantially to spreading of the material but substantially restricts the size of the passage, is the cause of additional yyear and energy consumption, whilst material can easily become stuck between the cone-shaped central section and the feed edge, yvhich impedes the flow through the device If fine or sticky' matenal is metered, it can be effective to arrange a pointed cone on the central section, which cone has a height approximately equal to that of the feed edge, the sides running essentially parallel with those of the metermg screen

The feed edges of the guide members yvhich are rotating around the pillar as it

scrape the grains off the column The amount of granular material scraped off is the greater the more granular matenal is able to infiltrate into the space between the guides and the greater the length of the feed edge, which is achieved accordmg to the invention by constructing the guide members not with a higher, perpendicular feed edge, as is customary, but yvith a feed edge which is ananged oriented obliquely downwards, yvith the bottom point of the feed edge at a greater radial distance from the axis of rotation than the top point of the feed edge What is achieved by this means is that said pillar is now able to widen more undisturbed before it comes into contact with (is scraped off by) the guide members Because, when it "slumps", the pillar moves outyvards further at the bottom than at the top and therefore forms a sort of upπght cone of granular mateπal that widens (expands outwards) towards the bottom, scraping off yvith an inclined feed edge takes place in a (much) more natural manner than if scraping takes place yvith a feed edge arranged verticalh A feed edge oriented obliquely downwards is therefore more effective than increasing the height of a feed edge arranged vertically to a length equal to that of the inclined feed edge In contrast to a feed edge ananged vertically, y here the grains are mamly scraped off along the bottom part of the feed edge, an inclined feed edge picks up the grams over the full height and guides them over the guide surface Moreover, the diameter of the central section increases appreciably yvithout the movement of the grains being disturbed, so that the maximum capacity increases without more air having to be displaced, whilst grains of larger diameter can be processed It is important that no material can become stuck between the rotor blade, or central surface, and the feed edge under the influence of centrifugal force It is therefore preferable to avoid an acute angle here and to allow the feed edge to adjoin the rotor blade at an angle of 90° or more, vieyy ed from the axis of rotation This can be achieved, for example, by arranging the bottom part of the feed edge perpendicular to the rotor blade As has been stated, the material is not affected or is bareh affected by the rapidly spinning rotary movement of the central section yvhen it is metered in and comes into contact with the rotor and, provided it is not blocked, the granular stream moves outyy ards m a y irtually radial direction, viewed from a stationary standpoint Material that passes through the distπbution screen immediately after it has passed a feed edge is able to infiltrate further between the guide members than is material that passes said edge at a later point in time The feed edge comes into contact - directly or indirectly - with mateπal that is on or close to the distπbution screen at the point in time when the feed edge passes by and this can cause this material to be repulsed or propelled outwards By arranging a splash screen in the form of a secondary guide member, material that moves too far and too rapidly outwards and consequently is picked up by the guide surface only at the location of the dispensing surface, or is even not picked up at all, is collected, the moy ement being diverted m the direction of the feed surface of the guide surface In order to be guided effectiy eh. the material essentially only has to make contact with the dispensing surface of the guide member m such a way that it clings to and is guided over this surface over a relatively short distance Hoyvey er, it is preferable that the material is picked up by the guide member at an earlier point in time, pick-up further on can lead to disturbances because the rotational velocity at that pomt is much higher In order to function effectively, the splash member can be constructed yvith a relatively short splash surface, but can also be extended further towards the outer edge of the rotor so that the risk of disturbances is avoided completely The openings between the discharge edge and the end edge as it were form a dispensing port at this location The mateπal that is metered onto the central section is able to leave the rotor only v la these discharge ports What is achieved by this means is that the granular stream is guided m a completely deterministic manner - that is to say all grains are propelled outwards at virtually the same angle of flight and virtually the same speed of flight - in a spiral stream directed backwards viewed from a standpoint movmg with the rotor By this means it is essentially guaranteed that, if a co-rotating impact member is arranged m the spiral stream, all grains come into contact yvith this impact member, at virtually the same speed and virtually the same angle of impact This is extremely important in comminution processes

It is preferable also to make the bottom edge of the splash surface adjoin the rotor blade at an angle of 90° or more, whilst the splash surface as a whole extends towards the outer edge of the rotor m such a way that no material is able to become stuck against the splash surface or be retarded in its movement by the splash surface Material can also rebound upwards and it is therefore preferable to cover the guide members, at least around the central section, with a plate over the top

Finally, the guide members can be of symmetrical construction, in a form with the backs against one another, which doubles the life of the rotor

When the guide member is oriented towards the back, viewed in the direction of rotation, the combmation of the feed edge onented obliquely outu ards and a splash member has the advantage that a pump action is created there can be said to be a grain pump As a result of this pump action the matenal is sucked inwards immediately under high force

infiltrates more deeply into the space between the guide members As a result the disturbance effect of the feed edges (metering screen) decreases, while the capacity increases If the maximum capacity is not utilised it is possible to increase the number of guide members Such a grain pump has proved to be particularly effective in combination with a co-rotating impact member

BRIEFDESCRIPTION OFTHE DRAWINGS

For better understanding, the aims, characteristics and advantages of the method and the device of the invention which have been discussed, and other aims, characteristics and advantages of the method and the device of the my ention, are explained in the following detailed descπption of the method and the device of the invention in relation to accompanying diagrammatic drawings

Figure 1 shows, diagrammatically, a cross-section of a first rotor accordmg to the invention along A- A

Figure 2 shows, diagrammatically, a longitudinal section of said first rotor according to the invention along B-B

Figure 3 shows, diagrammatically, a cross-section of a second rotor according to the invention where the feed edges are not straight Figure 4 shows, diagrammatically, a plan view of a third rotor according to the invention where vanous types of splash members are arranged behind the guide members

Figure 5 shows, diagrammatically, a plan view of a fourth rotor according to the invention in the form of a gram pump with curved guide members and curv ed splash members parallel thereto

Figure 6 shows, diagrammatically, a plan view of a sixth rotor according to the invention with symmetncal guide members

Figure 7 shows, diagrammatically, a cross-section of a fifth rotor accordmg to the invention along C-C, which rotor is constructed with straight backvy ard-oπented guide members and relatively short curved splash members

Figure 8 shows, diagrammatically, a longitudinal section of said fifth rotor according to the invention along D-D, which rotor is constructed with straight backward-oriented guide members and relatively short curved splash members

BEST WAY OF IMPLEMENTINGTHE METHOD AND DEVICE OFTHE INVENTION

Reference will now be made in detail to the prefened embodiments of the method and dev ice of the mvention. examples of which are illustrated in the accompanying drawings While the inv ention will be descnbed in conjunction with the preferred embodiments, it will be understood that the descπbed embodiments are not intended to limit the invention specifically to those embodiments On the contrary the mvention is intended to cover altemativ es, modifications and equivalents, which mav be included within the spirit and scope of the invention as defined by the appended claims

Figures 1 and 2 show, diagrammatically, a first rotor (1) according to the mvention which is rotatable at least in one direction about a vertical axis of rotation (O), which rotor (1) is provided at the top with a hoπzontal beanng surface (13) that extends around said axis of rotation (O) to an outer edge (64) of said rotor ( 1 ) The material is metered onto the central section (3 ) of the rotor ( 1 ) with the aid of a metenng member (2) The metering member (2) consists of a metering pipe (4) the centre of which is coincident with the axis of rotation (0) The bottom, or outlet (6) of the metenng pipe (4) is at a height that is approximately the same as that of the top edge (7) of the guide members (8) A. stationary metering ring (9) is arranged around the outlet (6), which metering ring (9) is supported bv said metenng pipe (4) and prevents mateπal being able to escape to the outside through the opemng (10) between the metenng pipe (4) and the guide members (8) during metenng The central section (3) of said beanng surface (13) which serves as a metering surface is of flat hoπzontal construction The guide members (8) are arranged around the central section (3) and are earned bv said rotor (1) and bear on said beanng surface (13), which guide member (8) is provided with at least one guide surface (11) with a feed edge (12) and a discharge edge ( 16) for accelerating said material that is metered with the aid of said metering member (2) onto the central section (3) of said bearing surface (13), after which said metered matenal is fed past said feed edge (12) to said guide surface (11) which feed edge (12) is some distance a ay from said axis of rotation (O), which guide surface (11) is onented to the direction of rotation and m the honzontal direction extends between said feed edge

(12) and said discharge edge (16) towards said outer edge (64) of said rotor (1) and in the v ertical direction extends between a top edge (7) and a bottom edge (15) which adjoins said beanng surface

(13) The feed edge (12) does not run parallel to said axis of rotation (O), such that the radial distance from said axis of rotation (O) to the top point (19) of said feed edge (12), which is at the point where said feed edge (12) and said top edge (7) intersect one another, is less than the corresponding radial distance to the bottom point (17) of said feed edge (12), which is at the point where said feed edge (12) and said bottom edge (15) intersect one another The inclined feed edge (12) makes an angle (α ) with the bearing surface (13), whilst the straight line (14) with said top point (19) and said bottom point (17) thereon makes an angle (α") with said axis of rotation (0) It is preferable to avoid the angle (α') being less than 90° because material can become stuck in an acute angle It is preferable that the angle (α") is equal to or greater than 15°, possibly even equal to or greater than 30° The stream of granules that is metered via the metering pipe (4) onto the central section of said beanng surface (13) forms a sort of upright cone that is scraped off in an ev en (natural) manner by the inclined feed edge (12) and guided over the full height ov er the guide surface (11) to the outside The rapidly rotating feed edges (12) form, as it were, a metering screen (44) that the material has to pass through in order to be able to be picked up by the guide members (8) Figure 3 shows, diagrammatically. a second rotor (21) essentially identical to the first rotor (1). except that the feed edges (22)(23) adjoin the rotor blade (24) perpendicularly (α' = 90°) For this purpose the first feed edge (22) is of perpendicular construction along the bottom section (45). whilst the second feed edge (23) is of curved construction The rotor (21) is equipped with an upπght πm (46) that is earned by said rotor (21) and on the inside (47) has the shape of a cone that widens towards the bottom The diameter at the bottom of the cone is no greater than the diameter which the metenng screen (77) descnbes in this plane The outlet (48) of the metering member (49) is suspended in this cone, which prevents mateπal being able to escape to the outside whilst the conical shape prevents material being able to become stuck against the rotating πm and instead propels it downwards under the influence of the centπfugal force A pointed upright cone (83) that widens towards the bottom is arranged centrally on the central section (78), with the top (84) of said cone at the same height as the top point (85) of the feed edge (22), whilst the side (86) of the cone (83) runs essentially parallel to that of the metenng screen or feed edges (22)

Figure 4 shows, diagrammatically, a third rotor (25) where splash members (27)(28)(29) are ananged behind the guide members (26). which splash members extend towards the outer edge (34) ofthe rotor (25) Each splash member has a splash surface (30) with a start edge (31) and an endedge (32) The start edge (31 ) completely adjoins the feed edge (33) ofthe guide member (26) The splash members (27)(28)(29) prevent mateπal escaping between the guide members (26) to the outside without bemg effectively guided by the guide members (26) The first splash member (27) is of short and curved construction, the second splash member (28) is extended to a radial distance from the axis of rotation (35) that is approximately equal to the corresponding radial distance to the discharge edge (36) ofthe associated guide member (26) A dispensing port (37) between the discharge edge (36) and the end edge (50) ofthe second splash member (28) is produced as a result This dispensing port (37) guarantees that all grains leave the rotor (25) in a deterministic manner The third splash member (29) is constructed with a straight splash surface (38) The angle (β) winch the splash members (27)(28)(29) make with the radial line from the axis of rotation is preferably greater than 90° at all points along the splash surface However, it is possible, by orienting the guide members outwards to a limited extent, to allow granular mateπal to become stuck against the splash surface, so that an autogenous splash surface is produced, as a result of which wear is restricted However, material that sticks in this way can impede the passage and regular distnbution ofthe mateπal over the guide members Figure 5 shows, diagrammatically a fourth rotor (39) where both the guide members (40) and the splash members (41) are of curved construction, essentially parallel alongside one another, such that guide channels (42) are produced which open into a dispensing port (43), by which means a gram pump is constructed which propels the material to the outside in a completely deterministic manner Figure 6 sho s, diagrammatically, a fifth, symmetrical rotor (51 ) equipped with a symmetncal guide member (52) that is formed by two essentially identical guide members (55)(56) which are ananged back-to-back such that the discharge edges (57)(58) are coincident, whilst a symmetrical splash member (61) is ananged between the feed edges (59)(60) The symmetrical guide member (52) is so arranged that both feed edges (59)(60) are coincident with the edge (62) of the central section (63), so that the symmetncal guide member (52) as a whole has the shape of a sort of equilateral triangle By increasing the angle (δ¹) which the two guide surfaces (55)(56) now make (δ¹ - δ), an opening (79) is produced between one ofthe feed edges (80) and the edge (62) ofthe central section (63), as a result of which a splash member (81 ) is produced as discussed above, the end edge (67) being a greater radial distance from the axis of rotation (82) than is the start edge (68) The symmetrical guide member (53)(54) can be equipped with a hmge (69). which makes it possible to adjust the symmetncal guide member (53)(54) so that it is functional in the opposite direction of rotation

Figures 7 and 8 show a sixth rotor, which is prefened in combination with co-rotating impact members (70) and is equipped with guide members (71), the guide surface (72) of which is of straight construction and is oπented towards the rear viewed in the direction of rotation, preferably at an angle (84) of between 30° and 60°. and is equipped with relatively short splash members (73) which are of curved construction The central section (74) is of flat construction and extends to the discharge edges (75) of the guide members (71), whilst the guide members (71) are covered over the top by a cover plate (76)

The forgoing descriptions of specific embodiments of the present device ofthe invention have been presented for purposes of illustration and description They are not intended to be exhaustive of to limit the device ofthe invention ofthe precise forms disclosed, and obviously many modifications and variations are possible in light ofthe above feaching The embodiments were chosen and descπbed in order to best explain the principles of the device of the invention and its practical application, to thereby enable others skilled in the art to best utilize the device ofthe inv ention and vanous embodiments with vanous modifications as are suited to the particular use contemplated It is intended that the scope ofthe device ofthe mvention be defined by the Claims appended hereto when read and interpreted accordmg to accepted legal pnnciples such as the doctrine of equiv alents and reversal of parts

Claims

1. Device for accelerating a stream of granular or paniculate material with the aid of centrifugal force, comprising : -a rotor (1) that is rotatable at least in one direction about a vertical axis of rotation (0), which rotor (1) is provided at the top with an essentially horizontal bearing surface (13) that extends around said axis of rotation (0) to the outer edge (64) of said rotor (1);

-at least one guide member (8) that is earned by said rotor (1) and bears on said bearing surface (13), which guide member (8) is provided with at least one guide surface (11) with a feed edge (12) and a discharge edge (16) for accelerating said material that is metered with the aid of a metering member (2) onto the central section (3) of said bearing surface (13), after which said metered material is fed past said feed edge (12) to said guide surface (11), which feed edge (12) is some distance away from said axis of rotation (O), which guide surface (11) is oriented in the direction of rotation and in the horizontal direction extends between said feed edge (12) and said discharge edge (16) towards said outer edge (64) of said rotor (1) and in the vertical direction extends between a top edge (7) and a bottom edge (15) which adjoins said bearing surface (13);

-characterised in that said feed edge (12) does not run parallel to said axis of rotation (0), such that the radial distance from said axis of rotation (O) to the top point ( 19) of said feed edge (12) which is at the point where said feed edge (12) and said top edge (7) intersect one another, is less than the corresponding radial distance to the bottom point (17) of said feed edge (12) which is at the point where said feed edge (12) and said bottom edge ( 15) intersect one another.

2. Device according to Claim 1, wherein the radial distance from said axis of rotation (O) to said bottom point (17) is 25% greater than the corresponding radial distance to said top point (19).

3. Device according to Claim 1, wherein the straight line which has said bottom point (17) and said top point (19) thereon makes an angle ( ") with said axis of rotation (0) which is equal to or greater than 15°.

4. Device according to Claim 1, wherein the straight line which has said bottom point (17) and said top point (19) thereon makes an angle (α") with said axis of rotation (O) which is equal to or greater than 30°.

5. Device according to Claim 1, wherein said feed edge ( 12) is not of straight construction.

6. Device according to one ofthe preceding Claims, wherein, at the location where it adjoins said bearing surface (13), said feed edge (12) makes an angle (α') with said bearing surface (13) that is equal to or greater than 90°, viewed from said axis of rotation (O).

7. Device according to one ofthe preceding claims, wherein a top surface (5) is placed on said guide member (8), which top surface extends around said axis of rotation (O) at least as far as said discharge edge (16).