DE102020100087A1 - Throwing accelerator of a woodworking machine - Google Patents

Abstract

The invention relates to a throwing accelerator (1) for conveying wood chips with a rotor (10) which has several throwing blades (11) distributed in its circumferential direction, which are prepared for a feed stream directed transversely to the direction of rotation (R) of the rotor (10) (7) to convert wood chips into a discharge flow (8) of wood chips directed tangentially to the direction of rotation (R) of the rotor (10). The rotor (10) is accommodated in a housing (12) which has a supply passage (13) which enables the supply flow (7) and which has a discharge passage (14) which enables the discharge flow (8). According to one aspect, the housing (12) has a radial projection (15) or a radial step (15) on its radial inner surfaces facing the free ends of the throwing vanes, which has a radial gap (17) between the rotor (10) and the housing (12) narrowed in sections. According to another aspect, the radial gap (17) widens in the area in front of the discharge passage (14).

Description

The present invention relates to a throw accelerator, also called throw blower or wood chip blower, a wood processing machine for the production of wood chips / wood chips with a rotor and a housing according to the preamble of claim 1. Preferably, a throw accelerator according to the invention is used in a mobile wood chopper.

Background of the invention

Generic throw accelerators are arranged between a chopping unit and a throwing tower in order to convey chopped / chopped / carved / chipped material, so-called wood chips, to a filling store / wagon.

Using the chopping unit, wood chips can be produced from a wide variety of materials, e.g. plastic chips for recycling plastic / plastic material or metal chips for recycling scrap metal. The preferred application, however, is the use of wood chips as wood chips, which are used, for example, as fuel for heating systems or as a base material for pressboard. In order to transport the freshly chopped wood chips from the chopping unit to a central collection point, such as a filling truck, in a short time, a generic accelerator is required. Freshly chopped wood chips are fed to this, for example by one or more screw conveyors, which in turn is accelerated by a rotor of the throwing accelerator in such a way that it is conveyed into the filling truck along a throwing path, the course of which is determined, among other things, by the throwing tower. The kinetic energy that has to be fed to the wood chips so that it can be transported along the corresponding throwing path is transferred to the wood chips via throwing blades / driving shovels of a rotor.

In generic applications, the wood chips are fed to the accelerator essentially transversely, mostly perpendicularly, to the direction of rotation of the rotor and leave it essentially along the tangential direction of the rotor. In addition to the resulting change in direction of the wood chips, the speed between the supplied wood chips and the removed wood chips also has a high gradient. Accordingly, a high relative movement and thus relative friction between the wood chips itself and the throw accelerator occurs in the throw accelerator, which places high demands on an efficient design of the throw accelerator.

State of the art

Accelerators / blowers for wood chips, in particular wood chips, are known from the prior art. This is how the German utility model reveals DE 9419877 U1 a chipping mill in which a blower is arranged to transport wood chips from the chopping unit to a collection point.

Based on this utility model, the state of the art has been further developed, for example in order to provide more powerful and space-optimized chopping units and throwing accelerators. The wood chips are supplied to the throwing accelerators commonly used today from a direction that runs transversely to the direction of rotation of the rotor of the throwing accelerator.

Rotors are usually in the form of paddle wheels with throwing vanes. During operation of the throwing accelerator of the generic type, a dust and particle wedge of sawdust and fine wood splinters forms in the area of the free ends of these throwing blades between the radial end edges of the throwing blades and a radial inner surface of the throwing accelerator housing. This is due to the fact that the wood particles produced when chopping / chopping the wood chips condense into a wedge in the radial end area of the shovel. This dust and particle wedge is dragged along by the rotating rotor and creates friction on the radial inner surface of the housing. In the case of the throw accelerators known in the prior art, the radial housing section heats up shortly before the ejection opening (the transition area at which the housing of the throw accelerator deviates from its circular cylinder shape and extends further in the tangential direction of the rotor) to temperatures of up to 250 ° C.

An important design parameter when designing the throwing blades of the rotor of a throwing accelerator is the setting angle of the blade surface with respect to the radial direction of the rotor. In particular, sluggish angles are used here in order to generate higher centrifugal forces, ie the blade surfaces are generally positioned starting from the radial direction against the direction of rotation of the rotor. The more sluggish the blade surfaces are designed (the larger the angle of attack is selected with respect to the radial direction), the greater the centrifugal forces that arise in the throwing accelerator. On the one hand, this results in an improvement in the ejection behavior, but on the other hand, it generates higher frictional forces due to the dust and particle wedge and, as a result, greater wear and tear on the housing. Very sluggishly designed throwing blades also favor due to the more acute angle, that is trapped between the blade and the housing, the formation of a particle wedge.

Disadvantages of the prior art against this background are the high level of wear and tear and the high maintenance outlay in the radial transition area / housing section in front of the ejection opening and the limitation of practicable drag angles when designing the rotor.

Brief description of the invention

In view of these disadvantages in the prior art, the present invention is based on the object of minimizing the wear on the fan and in particular the formation of a dust wedge between the rotor and the housing.

The invention achieves a solution to the above-mentioned objects by means of a throwing accelerator which has the features of claim 1 or the features of claim 2. Advantageous embodiments of the accelerator are the subject of the respective subclaims.

• - Die Lebensdauer sowie die Leistungseffizienz des Wurfbeschleunigers sind erhöht, da das Entstehen eines komprimierten Keils von Neben- bzw. Abfallprodukten wie Sägemehl oder Holzsplitter, vermindert wird. Dies verringert deutlich die Reibungsverluste und damit auch die Temperatur des Wurfbeschleunigers im Betrieb.
• - Auch die Ausfallwahrscheinlichkeit wird minimiert, da das Einklemmen eines solchen Staubkeils verhindert wird.

For example, the following advantages can be derived from the configuration according to the invention:

• - The service life and the performance efficiency of the throwing accelerator are increased, since the creation of a compressed wedge of by-products or waste products such as sawdust or wood splinters is reduced. This significantly reduces the friction losses and thus also the temperature of the accelerator during operation.
• - The probability of failure is also minimized, since such a dust wedge is prevented from being trapped.

The subject of the invention is accordingly a throwing accelerator for transporting wood chips, which is preferably used in a mobile wood chopper. The throwing accelerator has the rotor mentioned at the outset, which has a plurality of throwing vanes / driving vanes distributed in its circumferential direction for conveying wood chips. The rotor according to the invention converts a supply flow of wood chips directed transversely to the direction of rotation of the rotor into a discharge flow of wood chips directed tangentially to the direction of rotation of the rotor during its transport of wood chips. The rate of the discharge flow exceeds the feed flow. Thus, in addition to the change in direction, the rotor also has an accelerating effect on the wood chips. The ejector accelerator also has a housing accommodating the rotor, which has a supply passage enabling the supply flow, i.e. a first, lateral (axial) opening, and which has a discharge passage enabling the discharge flow, i.e. a second, upper (radial / tangential) opening , having.

According to the invention, the housing or the housing inner surface is at least partially in the form of a circular cylinder jacket and preferably essentially concentric to the rotor. A radial gap is formed between the radial housing inner surface of this circular cylinder jacket-shaped section and the rotor or its envelope curve. In other words, the accelerator forms a radial gap, air gap or freewheel between the radially outer end regions (radial outer edges) of the throwing vanes and the radial inner surface of the housing facing them.

According to a first aspect of the invention, the radial gap is in or immediately (in the circumferential / rotational direction) in front of the transition area upstream of the discharge passage, at which the radial inner surface of the housing deviates from its circular cylindrical surface shape in order to enable the wood chips to be ejected in the tangential direction of the rotor , widened / expanded / enlarged. This means that, viewed in the direction of rotation of the rotor, the radial gap initially has a certain gap width and this gap width then (approx. 1 cm to 30 cm) in front of the (gently) shaped (bent) transition area into the discharge passage / throwing tower continuously or abruptly (i.e. ramp or step-like) widens. This is a deliberate widening / enlargement of the radial gap independent of the usual free space occurring in the transition area, which results from the transition from the accelerator to the discharge passage / throwing tower.

A widening / widening of the radial gap according to the invention has the effect that in the radial housing section in front of the transition area or in front of the discharge passage, the centrifugal force-related friction is abruptly removed. The area that experienced the greatest wear in the throwing accelerators known in the prior art and reached the highest temperatures during operation is thus relieved and the heat development is distributed more in the sections of the housing upstream against the direction of rotation of the rotor.

According to a second aspect, the radial inner surface of the housing has at least one step (or a projection / ledge / edge) which narrows the radial gap (viewed in the direction of rotation of the rotor), in particular suddenly (for example only along a narrow circumferential section).

A step according to the invention which suddenly narrows the radial gap (or a projection of the same type, which in the direction of rotation is in front of the Transition area) has the effect that the dust and particle wedge described at the beginning sticks to it (scraper effect) and is thus removed or at least loosened by the corresponding throwing blade when passing the step. This results in a drastic reduction in the friction on the radial inner surface when the accelerator is in operation.

A synergistic effect with particularly low wear results when the radial gap (seen in the direction of rotation of the rotor) initially narrows suddenly in order to inhibit the formation of dust wedges, and then widens again in the section (directly) in front of the transition area in order to reduce the friction in the transition area minimize.

According to a preferred embodiment of the invention, the at least radial step, viewed in the circumferential direction of the housing, can be arranged between the supply passage and the discharge passage. The area between the supply passage and the discharge passage is usually heated / worn the most by friction effects, since the largest quantities of wood chips are conveyed in this housing section (the carpet of wood chips is suddenly reduced behind the discharge passage). A radial step is therefore particularly advantageous in this area.

According to a further preferred aspect of the invention, the radial step narrowing the radial gap can be arranged upstream of the discharge passage by a distance of 10 to 50 cm, viewed in the circumferential direction of the housing, counter to the direction of rotation of the rotor. The radial inner surface of the housing in the area in front of the discharge passage is usually exposed to the highest frictional loads and heats up the most during operation, since the highest centrifugal forces act on the wood chips in this area. It is not uncommon for this housing section upstream of the discharge passage to heat up to well over 200 ° C. in the case of throwing accelerators known in the prior art. In this area of the accelerator, which is particularly maintenance-intensive in the prior art, the radial step according to the invention has proven to be particularly advantageous.

According to a further preferred exemplary embodiment of the invention, the radial step (or the projection) can run essentially transversely to the direction of rotation (parallel to the axial direction of the rotor) in order to be able to effectively remove the dust and particle wedge. For this purpose, the radial step / the projection can preferably extend over the entire width of the interior of the housing.

According to a further preferred aspect of the invention that may be claimed independently, the radial step (or the radial projection) can be formed by a hard metal insert. In other words, a hard metal insert or bar / strip can preferably be arranged on the radial inner surface of the housing, which insert protrudes into the radial gap or narrows it. Since the flow of wood chips constantly breaks at the radial step and this is therefore exposed to high wear, the design as a hard metal insert increases the service life of the same.

According to a preferred development of the aforementioned aspect, the hard metal insert forming the radial step or the projection can be arranged on an exchangeable or releasably fastened wear plate, which lines the radial inner surface of the housing in an area upstream of the discharge passage. As already mentioned, the radial inner surface of the housing is subject to high wear. Lining this area with replaceable wear plates makes it possible to renew worn areas with little effort. More preferably, wear plates can have a hard coating on their surface facing the inside of the housing in order to further increase the wear resistance. Alternatively, a wear plate per se (without a hard metal insert) can also form the radial step that narrows the radial gap with its side edge facing away from the discharge passage.

According to a further preferred exemplary embodiment of the invention, the hard metal insert can be materially connected to the wear plate, in particular soldered in.

According to a further preferred aspect of the invention, a plurality of radial steps or projections spaced apart from one another, preferably by 10 to 50 cm, particularly preferably 15 to 30 cm, can be formed in the circumferential direction of the housing. Tests by the applicant have shown that such an arrangement can bring about a temperature reduction of the radial inner surface in the transition area in front of the discharge passage of up to 20 ° C. per radial step.

According to a preferred development, several wear plates can be arranged one after the other in the circumferential direction, each of which has a hard metal insert that forms a radial step. These wear plates preferably line the radial inner surface of the housing in the area between the supply passage and the discharge passage (at least partially). Particularly preferred is the area upstream of the transition area or the area which extends to the discharge passage counter to the direction of rotation of the rotor by approx. 5 to 30 cm is upstream, not lined with wear plates, so that the radial gap in this area (according to the first aspect of the invention) is significantly wider than in the area lined with wear plates.

According to a further preferred aspect of the invention, the at least one radial step or the projection can protrude by a distance between 0.5 to 10 mm with respect to the adjoining radial inner surface of the housing in order to narrow the radial gap.

According to a further preferred exemplary embodiment of the invention, the throwing blades of the rotor can be arranged at a dragging angle. They can particularly preferably be set at an angle of 5 ° to 30 ° against the direction of rotation of the rotor relative to the radial direction.

A further preferred aspect of the present invention, which is optionally to be claimed independently, relates to a throwing accelerator according to the preamble of claim 1, which has an upper separating blade in the area of the discharge passage. The upper separating blade is arranged in the area of the housing tongue, i. H. in the area of the rear edge of the discharge passage viewed in the direction of rotation of the rotor. The separating blade extends essentially against the direction of rotation of the rotor and is structurally coordinated with the rotor in such a way that the freewheel between the upper separating blade and the radial end edges of the throwing blades is less than 10 mm, preferably less than 4 mm. The upper separating blade is passed by the respective throwing shovels after the wood chips have been ejected through the discharge passage and has the effect that the shovel is cleaned after ejection. In this way, material residues can be prevented from solidifying to form a wedge while the distance between the discharge passage and the supply passage is covered. This feature per se lowers the wear and tear of an accelerator, but it can optionally and synergistically be combined with one of the aforementioned aspects.

• 1: einen Wurfbeschleuniger, der an ein Hackaggregat angeschlossen ist;
• 2: den Wurfbeschleuniger in einer vom Hackaggregat getrennten Ansicht;
• 3: den Wurfbeschleuniger in einer Ansicht mit einem Pfeil, der die Drehrichtung des Rotors angibt;
• 4: den Wurfbeschleuniger in einer weiteren Ansicht;
• 5 den Wurfbeschleuniger gemäß einem bevorzugten Ausführungsbeispiel in einer perspektivischen Ansicht mit einer ausgeklappten Außenwand;
• 6 den Wurfbeschleuniger gemäß dem bevorzugten Ausführungsbeispiel in einer Schnittdarstellung mit zugeklappter Außenwand;
• 7A eine Detailansicht zur Veranschaulichung eines Radialspaltes zwischen Rotor und Gehäuse sowie der radialen Stufe im Bereich vor dem Abfuhrdurchgang;
• 7B eine Detailansicht zur Veranschaulichung der radialen Stufe im Bereich vor dem Zufuhrdurchgang;
• 8 eine perspektivische Ansicht des Rotors gemäß dem bevorzugten Ausführungsbeispiel;
• 9 eine Draufsicht auf den Rotor gemäß dem bevorzugten Ausführungsbeispiel
• 10 eine perspektivische Ansicht auf eine Verschleißplatte gemäß einem bevorzugten Ausführungsbeispiel;
• 11 eine Schnittdarstellung durch die Verschleißplatte gemäß dem bevorzugten Ausführungsbeispiel; und
• 12 eine Schnittansicht durch den Wurfbeschleuniger mit angeschlossenem Hackaggregat.

The invention is explained in more detail below on the basis of preferred exemplary embodiments with reference to the accompanying figures. Show it:

• 1 : a throwing accelerator connected to a chopping unit;
• 2 : the accelerator in a separate view from the chopping unit;
• 3 : the accelerator in a view with an arrow indicating the direction of rotation of the rotor;
• 4th : the accelerator in a further view;
• 5 the accelerator according to a preferred embodiment in a perspective view with an unfolded outer wall;
• 6th the accelerator according to the preferred embodiment in a sectional view with the outer wall closed;
• 7A a detailed view to illustrate a radial gap between the rotor and the housing and the radial step in the area in front of the discharge passage;
• 7B a detailed view to illustrate the radial step in the area in front of the feed passage;
• 8th a perspective view of the rotor according to the preferred embodiment;
• 9 a plan view of the rotor according to the preferred embodiment
• 10 a perspective view of a wear plate according to a preferred embodiment;
• 11 a sectional view through the wear plate according to the preferred embodiment; and
• 12th a sectional view through the accelerator with attached chopping unit.

The figures are merely of a schematic nature and are used exclusively for understanding the invention. The same elements are provided with the same reference symbols.

In 1 is a throw accelerator / blower 1 shown, the / that to a chopping unit 2 connected / flanged / tied up. Together are the throw accelerator 1 and the chopping unit 2 preferably arranged on a mobile wood chopper in order to produce wood chips from already felled tree trunks. About a feed table 3 , on which various, not shown / not visible from this perspective rollers for raw material guidance, preferably for tree trunk guidance, are arranged, the medium to be shredded, preferably wood, is in the chopping unit 2 drawn in and shredded by a cutting tool / chopping rotor. The chopping unit 2 has a maintenance cover 4th which covers it safely and robustly and which can only be opened in the event of maintenance. The wood chips reduced by the cutting tool are preferably fed via an in 1 screw conveyor, not shown in detail, to the throwing accelerator 1 in a feed stream 7th related to 2 again is treated, supplied. The throwing accelerator according to the invention 1 is designed in such a way that it moves the wood chips along a throwing tower, not shown, in a discharge stream 8th , which is also related to 2 is treated again, promoted further.

2 provides the throw accelerator 1 for a better understanding of the material flows from the chopping unit 2 detached. Along an inlet stream 6th the medium to be shredded becomes on the infeed table 3 into the chopping unit 2 promoted. After the chopping / chopping / shredding into wood chips, this is along the feed stream 7th from a feed chute on the chopping unit side 5 the throwing accelerator 1 fed. For moving the wood chips out of the feed shaft 5 out in this are preferably screw conveyors ( 44 in 12th ) arranged.

The feed stream 7th runs orthogonally to a rotor housing side surface 9 . So is one especially related to that 3 and 8th rotor described in more detail 10 designed so that it can control the feed stream 7th , which runs along the direction of its axis of rotation, but offset from it radially outwards, in its direction and in its speed in a discharge flow 8th transforms. The discharge stream 8th lies in a plane to which the feed stream 7th stands vertically.

It should also be noted that the arrows 7th and 8th are to be understood as a kind of resultant from the stream of wood chips composed of countless wood chips. It is immediately obvious to a person skilled in the art that with a corresponding flow of wood chips related to the individual wood chips, velocity or movement vectors can occur along any spatial direction. So give the feed stream shown 7th and the discharge flow 8th only the direction of the resulting motion vector of all wood chips.

With reference to 3 is the functionality of the accelerator described above 1 easy to understand. The throwing accelerator 1 is made up of a rotor 10 and one the rotor 10 housing housing 12th together. The case 12th is fixed in space in its environment, such as the wood chopper, while the rotor 10 , is driven in rotation, for example by a toothed belt pulley on the rotor side, which is in engagement with a belt drive.

The previously in 2 Chopping unit-side feed chute shown 5 stands with one of the housing 12th in the rotor housing side surface 9 formed feed passage 13th so in contact that the wood chips from the chopping unit 2 into the throwing accelerator 1 got. The shape and dimension of the cross section of the feed chute 5 and the feed passage 13th are therefore in a geometric dependency, without necessarily having the same shape. The feed passage 13th is defined by housing edges 13a, 13b and 13c, as in FIG 3 is easy to see.

The feed passage 13th is in a height direction of the accelerator 1 below the feed chute 5 arranged. That is, the lower feed passage housing edge 13b is below the lower edge of the feed chute 5 runs. This has the effect that wood chips from the chopping unit are removed 2 to the throw accelerator 1 is promoted when transitioning to the accelerator 1 does not build up as it falls off easily. So there is a radial step between the lower edge of the feed chute 5 and the bottom of the case 12th educated.

As in 3 clearly visible are on the rotor 10 several throwing shovels 11 for take-away / shoveling of wood chips arranged to remove wood chips from the area of the feed passage 13th through a discharge passage 14th to convey and eject from this. To the throwing shovels 11 There are high requirements in terms of strength. The rotor rotates during operation 10 in a preferred embodiment in the range between 300 to 800, preferably 600, revolutions per minute. In the in 3 direction of rotation shown 23 of the rotor 10 is the resulting speed of the wood chip flow when it is fed through the feed shaft 13th about zero on average. That means the throwing shovels 11 with a rotor diameter 29 of preferably over a meter (1230 mm in the preferred embodiment shown) hit the wood chips with high force due to the high relative speed. On the one hand, to ensure that the wood chips are reliably taken along in the direction of the discharge passage 14th to enable and on the other hand to prevent excessive wear, are the throwing blades 11 robustly shaped. This is what the throwing shovels are for 11 according to the invention along one of its side surfaces with a for 8th rotor wall disk described in more detail 21 connected.

It is in 3 also perpendicular to the direction of rotation 23 standing transverse direction 24 illustrates along which the feed stream 7th mentioned above in connection with 2 has been explained. Tangential to the direction of rotation 23 stands the tangential direction 25th , along which the discharge flow 8th , which is also related to 2 has been explained.

It will be in the 3 and 4th clearly that the case 12th is shaped essentially as a circular cylinder. In addition to the already mentioned side surface 9 the rotor housing therefore has a circular cylindrical jacket surface 9a. The jacket surface 9a of the circular cylinder shape is in the area in front of the discharge passage 14th interrupted and instead extends in the tangential direction 25th further. In other words, the case has 12th the already mentioned rotor housing side surface 9 as well as a circumferential surface 9a in its circumferential direction. However, the jacket surface 9a does not even run around completely, but the circular shape (viewed in cross section) is in the area of the discharge passage 14th interrupted and the jacket surface is here as tangential to the direction of rotation of the rotor 23 extending or tangential lateral surface 9b essentially straight in the tangential direction 25th away. This has the consequence that from the rotor 10 Accelerated and carried wood chips in this transition area 32 of the housing 12th from the circular cylindrical jacket surface 9a into the tangential jacket surface 9b under the action of centrifugal force (or due to its mass inertia) the throwing accelerator 1 in the tangential direction 25th through the discharge passage 14th leaves.

In 4th is the case 12th shown in a different view. The tangential section of the lateral surface 9b can be clearly seen in this view. The Indian 4th circled area of the throwing accelerator 1 that is the transition area 32 from the circular cylindrical jacket surface 9a to the tangential jacket surface 9b is exposed to particularly high loads during operation, since here the largest material flow with the highest relative speed or the highest centrifugal force ensures high friction with the radial inner surface of the jacket surface 9a, 9b. In the case of throwing accelerators known from the prior art, this transition area occurred 32 therefore case temperatures of up to 250 ° C during operation. The result was a high material load and high wear in this housing section.

The applicant has surprisingly found that a main factor contributing to the high frictional loads in the transition area 32 the radial inner surface of the housing 12th in the area in front of the discharge passage 14th leads, is a dust and particle wedge between the free ends (seen in the radial direction) of the throwing vanes 11 and the radially inner surface of the housing 12th or the inside of the lateral surface 9a, 9b forms. Said dust and particle wedge is created by the fact that sawdust and sawdust are compressed into a solid wedge under the action of centrifugal force in an area upstream of the throwing blade tip. This then jams in the radial gap 17th between the free ends of the throwing blades 11 and the radially inner surface of the housing 12th and ensures high levels of friction.

5 shows a throw accelerator 1 according to a preferred embodiment of the invention, which provides a remedy for the problem described above. In the illustration shown is the housing 12th opened and gives a view of the radial inner surface 16 or the inside of the lateral surface 9a of the housing 12th in the area in front of the discharge passage 14th free. This area is in the illustrated preferred embodiment of the invention with a number of wear plates 20th lined, which are arranged one after the other in the circumferential direction. The circular cylindrical jacket surface 9a of the housing 12th is concentric with the rotor 10 arranged and there is a predetermined radial gap 17th provided between these two components.

6th shows the radial gap for better illustration 17th the throw accelerator 1 according to the preferred embodiment in a folded state in cross section. A case inside diameter 28 represents the inside diameter of the circular cylindrical housing part. The housing inside diameter 28 exceeds an outer rotor diameter in its amount 29 by a certain amount so that the radial gap 17th or a defined air gap / freewheel between the rotor 10 and housing 12th is trained.

The lining of the radially inner surface of the housing 12th with the wear plates 20th narrows the radial gap 17th in the example shown to approx. 3 mm. In the transition area 32 or in the section of the housing 12th , the discharge passage 14th approx. 15 to 30 cm against the direction of rotation of the rotor 23 is upstream, the radial inner surface is no longer with a wear plate 20th lined. As a result, the radial gap widens 17th in the illustrated embodiment in the transition area or immediately in front of the transition area suddenly to about 15 mm. This step-like expansion or broadening of the radial gap 17th through the discharge passage 14th facing edge of the transition area 32 adjacent wear plate 20th is best in the detailed display of the 7A to recognize. This has the advantageous effect that the area that is most stressed by friction in conventional throwing accelerators can be relieved.

As best in the 7B can be seen, arises from the lining of the radial inner surface 16 of the housing 12th with wear plates on the discharge passage 14th opposite to the direction of rotation of the rotor most distant wear plate 20 'a radial step 15th showing the radial gap 17th narrowed. At this radial step 15th , the dust and particle wedge gets stuck during operation because the radial gap is located 17th in the direction of rotation of the rotor 10 seen suddenly narrowed.

In the throwing accelerator 1 according to the preferred embodiment is at the from the discharge passage 14th remote side edge of each wear plate 20th a hard metal insert 18th arranged. In the illustrated embodiment, the hard metal inserts 18th soldered to the wear plates. The hard metal inserts 18th each extend in the axial direction of the rotor, ie transversely to the direction of rotation 23 . In addition, the hard metal inserts extend 18th essentially over the entire width of the housing 12th or the jacket surface 9a. Because the carbide inserts 18th each have a greater radial extent (or thickness) than the wear plates 20th on which they are arranged, each forms hard metal insert 18th one the radial gap 17th narrowing stage 15th or the radial gap 17th narrowing lead. In the preferred embodiment, the hard metal insert jumps 18th by 1 mm in the radial direction compared to the wear plate 20th in front of which it is arranged. This has the consequence that every time a throwing shovel is used 11 a hard metal insert 18th During the rotation, the dust and particle wedge passes from the tip of the throwing shovel 11 removed or at least loosened. At the one from the discharge passage 14th The wear plate 20 'furthest away from the direction of rotation of the rotor, consequently, its hard metal insert 18' forms the radial step 15th which narrows the radial gap from approx. 15 mm to approx. 1 to 2 mm.

Another preferred aspect of the present invention, which is also described in 6th is clearly visible, concerns the separating blade 22nd , which is arranged in the area of the housing tongue. The housing tongue is the one in the direction of rotation of the rotor 23 viewed the rear edge of the discharge passage 14th due to the discharge passage 14th interrupted circular cylindrical shape of the housing 12th forms an acute angle in the side view. The separating blade 22nd extends essentially against the direction of rotation of the rotor 23 and is structurally coordinated with the rotor in such a way that the freewheel between the upper separating blade 22nd and the radial end edges of the throwing vanes between 1 and 5 mm, preferably about 3 mm. The upper separating blade 22nd is from the respective throwing shovels 11 after ejecting the wood chips through the discharge passage 14th happens and has the effect that the throwing shovels 11 cleaned after ejection. In this way it can be prevented that material residues, such as sawdust and wood splinters, solidify to form a wedge during the section between the discharge passage 14th and feed passage 13th is covered. In this area between the discharge passage 14th and feed passage 13th (before adding new material) is also the radial gap for this purpose 17th chosen larger. Through the top separating blade 22nd can be the wear and tear of the accelerator 1 can be reduced even further, since the throwing vanes have already been cleaned or “wedge-free” at the feed passage 13th arrive.

The individual wear plates 20th (best in 10 can be seen) have in the illustrated embodiment in the circumferential direction of the accelerator 1 seen a total extension of approx. 140 mm, so that the individual radial steps / projections 15th or the hard metal inserts 18th are also spaced from one another by 140 mm in the circumferential direction. In the in 6th illustrated embodiment are four wear plates 20th provided so that each throwing shovel 11 four at each revolution thanks to carbide inserts 18th formed steps / protrusions 15th happens. The applicant was able to request such an arrangement per step / protrusion 15th a reduction in the housing temperature in the transition area 32 from the circular cylindrical jacket surface 9a to the tangential jacket surface 9b of approx. 20 ° C per step / projection 15th determine. The arrangement shown allows the temperature of the transition area 32 Lower the temperature significantly below 200 ° C during operation, which also noticeably reduces wear.

The wear plates 20th according to the preferred embodiment are in 10 and 11 shown in detail. It is easy to see here that the wear plates 20th a number of breakthroughs 30th have through which the wear plates 20th using fasteners 19th (screws in the preferred embodiment) on the radial inner surface of the housing 12th are releasably fastened. Such a releasable attachment of the radially inner surface 16 lining wear plates 20th has the advantage that these can be replaced when they are worn out accordingly. The breakthroughs 30th each have subsidence 31 to countersink the screw heads. This is due to the narrowed radial gap 17th in the area of the wear plates 20th needed to collide with the rotor 10 to avoid. The wear plate 20th is made in the preferred embodiment from a boiler plate with hard coating to increase the wear resistance.

In the side sectional view of the 11 is easy to see that the hard metal insert 18th in the installed state has a greater radial extent or protrudes further radially inward than the rest of the wear plate 20th . In the example shown, the hard metal insert jumps 1 mm radially inward relative to the wear plate 20th in front. As a result, the furthest from the discharge passage 14th removed hard metal insert 18 'a radial step 15th forms that by a greater distance (approx. 10 to 15 mm) compared to the radial inner surface 16 of the housing 12th protrudes than that through the remaining cemented carbide inserts 18th formed protrusions 15th . The hard metal insert 18th is preferably made of a tungsten carbide hard metal (90% WC 10% Co).

8th shows an isolated representation of the rotor 10 . The rotor 10 is characterized by a high degree of constructive peculiarity. The throwing shovels 11 are on one side on a rotor wall disk 21 arranged. The rotor wall disk 21 fixes the throwing blades 11 first of all on a radially inner throwing vane holder 21a to get the torque of the rotor 10 , that is, the torque applied to the rotor wall disk 21 on the throwing shovels 11 to guide so that they feed kinetic energy to the wood chips. The radially inner throwing vane holder 21 Supporting a are the throwing vanes 11 also via radially outer throwing vane receptacles 21b with the rotor wall disk 21 coupled. This coupling takes place, for example, via a welded connection and additionally or alternatively also via a non-positive connection such as a screw connection. Thus, the rotor wall disk makes it possible 21 , the throwing shovels 11 initiate force at several points of attack, which increases the robustness of the throwing blades 11 elevated.

In addition to the increased robustness, the rotor wall disc enables 21 the effect of a "moving wall". This enables the relative movement between the throwing blades to disappear, that is to say to be reduced to zero 11 and thus a drastic reduction in friction at this point.

The throwing shovels 11 each have a also in 8th easily recognizable recess 27 on. The recesses 27 are in the preferred embodiment as a substantially circular recess in the feed stream 7th (see. 2 ) facing side edge of the throwing shovel 11 educated. The recess 27 is here in a middle area of the feed stream 7th facing side edge of the throwing shovel 11 arranged, ie between and at a certain distance from the respective radial ends of the throwing blade. The recess 27 does not have to be circular, but can also assume any other geometries. Furthermore, the recesses 27 advantageously arranged so that they are in the radial direction at the level of the feed stream 7th are arranged. It can be prevented in this way that the feed stream 7th when passing through the feed passage 13th through the throwing shovels 11 backed up. That is, even if a throwing shovel appears at a given moment 11 before the feed passage 13th is located and this partially covers, the feed stream can into the recess 27 flow in until the scoop 11 the feed passage 13th releases again. Due to the centrifugal force, the wood chips are essentially transported over the radial end area of the shovel 26th to the discharge passage 14th promoted. It is beneficial if the throwing shovel 11 seen in the radially outward direction following the recess 27 widened so that they are substantially the entire width of the interior of the housing 12th fills in to maximize flow.

9 Figure 3 shows a top view of the insulated rotor 10 according to the preferred embodiment. In this view it is particularly easy to see that the throwing shovels 11 or whose active surfaces are set at a slow angle with respect to the radial direction α (opposite to the direction of rotation). In other words, the radially outer blade end region runs 26th compared to an exactly radially aligned throwing blade. The dragging design of the throwing shovels 11 significantly improves the ejection behavior, but also provides more friction on the radial inner surface due to higher centrifugal forces 16 of the housing. In the embodiment shown, the drag angle is approximately 33 °.

With reference to 12th is the throw accelerator 1 shown in a state in which he is attached to the chopping unit 2 is flanged. A screw conveyor 44 is here in the feed shaft 5 arranged to bring wood chips into the interior of the accelerator 1 to wear.

Wood chips that are attached to the rotor 10 facing end of the feed chute 5 falls along a rotor inlet slope 42 in a radially outer edge area 45 of the rotor 10 and there forms the carpet of wood chips described at the beginning. That gradient 42 is made possible by a radial step. This denotes the step that extends between the lower feed passage housing edge 13b and the radially inner surface 16 in the lower part of the housing 12th forms. This radial step or the slope 42 works synergistically with the recesses 27 in the throwing shovels 11 together, since the wood chips supplied fall down after entering the housing 12th further counteracts a material jam. It is in 12th good to see that the recess 27 begins radially outside at the level of the lower feed passage housing edge 13b. In other words, it is in the radially outer edge area 45 , which also conveys the majority of the wood chips, the full throwing shovel width is available during the recess 27 seen in the radial direction is positioned approximately in the middle of the throwing vane, so that it is in its radial position with the feed passage 13th corresponds. The woodchip carpet that is in the edge area 45 ausformt points only to the radial inner surface 16 a relative friction component. Because of the rotor wall disc 21 the woodchip carpet is transported with little friction laterally. In other words, the wood chips fall along the incline of the rotor inlet 42 is guided into the inside of the rotor, so on the carpet of wood chips, which is in the outer edge area 45 of Rotor 10 trains. Because the rotor wall disk 21 with the throwing shovel 11 with turns, wood chips have extremely low friction along the direction of rotation 23 of the rotor 10 transported.

List of reference symbols

1

Throwing accelerator;

2

Chopping unit;

3

Entrance table;

4th

Maintenance cover;

5

Feed chute;

6th

Feed stream;

7th

Feed stream;

8th

Discharge flow;

9

Rotor housing side surface;

10

Rotor;

11

Throwing shovel;

12th

Casing;

13th

Feed passage;

14th

Discharge passage;

15th

radial step / radial projection;

16

radial inner surface;

17th

Radial gap;

18th

Hard metal insert;

19th

Fastener / screw;

20th

Wear plate;

21

Rotor wall disk;

21a

Radially inner throwing vane holder;

21 b

Radially outer throwing vane holder;

22nd

Upper Separating Blade / Housing Tongue;

23

Direction of rotation / direction of rotor rotation;

24

Transverse direction;

25th

Tangential direction;

26th

Radial blade end area;

27

Recess;

28

Housing inside diameter;

29

Rotor outer diameter;

30th

breakthrough

31

Lowering

32

Transition area;

42

Rotor inlet gradient;

44

Auger;

45

Radial outer edge area

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 9419877 U1 [0005]

Claims (10)

Litter accelerator (1) for transporting wood chips, with a rotor (10) which has several throwing blades (11) distributed in its circumferential direction, which are prepared for a feed stream (7) directed transversely to the direction of rotation (23) of the rotor (10) to convert wood chips into a discharge flow (8) of wood chips directed tangentially to the direction of rotation (23) of the rotor (10), and with a housing (12) which houses the rotor (10) and which has a feed passage (7) that enables the feed flow (7) 13), and which has a discharge passage (14) which enables the discharge flow (8), characterized in that a radial gap (17) between the radially outer end regions (26) of the throwing blades (11) and the radial inner surface (16) of the housing is formed, viewed in the circumferential direction of the housing (12) in an area upstream of the discharge passage (14) counter to the direction of rotation (23) compared to a counter to the direction of rotation (23) benac Hated section of the radial gap (17), in particular in a stepped manner, widened. Litter accelerator (1) for transporting wood chips, with a rotor (10) which has several throwing blades (11) distributed in its circumferential direction, which are prepared for a feed stream (7) directed transversely to the direction of rotation (R) of the rotor (10) converting wood chips into a discharge flow (8) of wood chips directed tangentially to the direction of rotation (R) of the rotor (10), and with a housing (12) which houses the rotor (10) and which has a feed passage (7) enabling the feed flow (7) 13), and which has a discharge passage (14) enabling the discharge flow (8), characterized in that the housing (12) has at least one radial inner surface (16) on its radial inner surface (16) facing the radially outer end regions (26) of the throwing blades (11) radial step (15) or a radial projection which / which narrows a radial gap (17) between rotor (10) and housing (12) in sections. Throwing accelerator according to the Claims 1 and 2 , in which the radial gap (17), viewed in the direction of rotation of the rotor (23), initially narrows by a radial step (15) in the radial inner surface (16) and widens again in the transition region (32). Accelerator (1) according to Claim 2 or 3 , characterized in that the radial step (15) narrowing the radial gap (17) in the circumferential direction of the housing (12) and counter to the direction of rotation (27) of the rotor (10) by a distance of 20 to 50 cm from the discharge passage (14) is arranged upstream Throw accelerator (1) according to one of the Claims 2 to 4th , characterized in that the radial step (15) is formed by a hard metal insert (18). Accelerator (1) according to Claim 5 , characterized in that the hard metal insert (18) forming the radial step (15) is arranged on an exchangeable or releasably fastened wear plate (20) which the radial inner surface (16) of the housing (12) in one of the discharge passage (14) upstream area lines. Accelerator (1) according to Claim 6 , characterized in that the hard metal insert (18) is integrally connected to the wear plate (20), in particular soldered. Accelerator (1) according to Claim 4 , characterized in that, viewed in the circumferential direction of the housing (12), several wear plates (20) are arranged one after the other, each having a hard metal insert (18) forming a radial step (15). Throw accelerator (1) according to one of the Claims 2 to 8th , characterized in that the radial step (15) projects by 0.5 to 15 mm with respect to the radial inner surface (16) of the housing (12) in order to narrow the radial gap (17). Throw accelerator (1) according to one of the Claims 1 to 9 , characterized in that the housing (12) has a separating blade (22) in the area of the housing tongue or in the area of the rear edge of the discharge passage (14) in the direction of rotor rotation (23).

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