(19)
(11) EP 1 070 788 B1

(12) EUROPEAN PATENT SPECIFICATION

(45) Mention of the grant of the patent:
23.05.2007 Bulletin 2007/21

(21) Application number: 00114932.7

(22) Date of filing: 18.07.2000
(51) International Patent Classification (IPC): 
E01C 23/088(2006.01)

(54)

Road scarifier with containment chamber housing the milling drum

Fräsmaschine mit eingehauster Fräswalze

Machine de fraisage avec tambour de fraise dans une chambre de confinement


(84) Designated Contracting States:
DE FR GB IT

(30) Priority: 23.07.1999 IT VI990061 U

(43) Date of publication of application:
24.01.2001 Bulletin 2001/04

(73) Proprietor: CATERPILLAR PAVING PRODUCTS INC.
Minnesota 55445 (US)

(72) Inventor:
  • Bitelli, Romolo
    S. Lazzaro (BO) (IT)

(74) Representative: Wagner, Karl H. et al
WAGNER & GEYER Patentanwälte Gewürzmühlstrasse 5
80538 München
80538 München (DE)


(56) References cited: : 
EP-A- 0 735 193
US-A- 3 802 742
   
       
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description


    [0001] The present invention relates to road scarifiers with a containment chamber of the milling drum.

    [0002] As is known, road scarifiers are machines used for removing bitumen road surfaces, concrete road surfaces, or the like, which cover for example road sites.

    [0003] They substantially comprise a frame mounted on wheels provided with a propulsion unit, with a driving seat for the operator, and with a milling drum arranged in contact with the road surface to be removed.

    [0004] The milling drum presents a plurality of active elements, realised with different shapes according to the use requirements, which - during the rotation of the milling drum - crumble the road surface with which they come into contact.

    [0005] The milling drum is contained in a chamber laterally delimited by the frame body sides, and on the upper side, for at least a portion, by a curved wall with the concavity facing the active elements, and spaced from them.

    [0006] The material removed by the active elements is directed - by centrifugal force - towards the above curved wall, which conveys it onto a conveyor belt, which unloads it, for example, into the body of a lorry.

    [0007] Fig. 1 shows a prior art road scarifier M with a milling drum T housed in a containment chamber C, wherein it can be seen that the curved wall P is realised with a profile concentric to the milling drum T by an angle α of about 90°.

    [0008] The air gap defined between the curved wall P and the periphery of drum T is constant, and has a minimum radial width R along its entire extension, so as to guarantee an even distribution of the milled material into the air gap itself, preventing it from accumulating above all on the front side of the drum.

    [0009] Nevertheless, it has been noted that an excessive reduction of the radial width R causes a marked and fast wear of the curved wall due to the contact with the milled material and due to the significant pressure that the latter exerts on it, since it is constrained into a narrow space.

    [0010] In particular, the portion of wall which is more affected by this phenomenon is the upper central portion, the farthest from the ground, identified with W in Fig. 1, wherein the milled material collects by virtue of the transport effect due to the centrally-convergent helical arrangement of the active elements A arranged onto the milling drum T.

    [0011] This implies the need of frequently overhauling or entirely or partly replacing the curved wall P.

    [0012] A solution adopted in the attempt to reduce said disadvantage consists in realising the curved wall P with high-resistance materials, adapted to delay its wear.

    [0013] However, it is evident that the use of said materials implies an increase in the manufacturing costs, and an increase of the price of spare parts.

    [0014] Nevertheless, it has been noted that the use of said materials does not solve the problem at the root, since its reasons are not eliminated.

    [0015] US-A-3 802 742 was used as a basis for the preamble of claim 1. According to this document, wet cutting of pavement into multiple grooves to impart antiskid properties thereto produces a slurry of solid particles in water. In treatment prior to disposal of the slurry, particles of cutting material are reclaimed from the slurry for subsequent reuse, and pavement particles are recovered optionally therefrom. Mobile equipment is provided for accomplishing such multiple grooving of pavement and such reclamation or recovery of particulate material.

    [0016] The containment chamber of the cutting drum has a curved wall of constant radius, but the air gap between curved wall and drum is of variable radial width.

    [0017] The present present invention has the object of obviating said disadvantages.

    [0018] First object of the present invention is that of providing a road scarifier comprising a milling drum and a containment chamber wherein the curved wall covering the drum should be less subject to wear than known embodiments.

    [0019] Another object is that of providing the chamber of the present invention as being realised using commercial steel plates.

    [0020] Last but not least, another object is that of providing the chamber of the present invention as having manufacturing costs not exceeding those of the chambers of the known type that are equivalent to it.

    [0021] Said objects are attained by providing a road scarifier as set forth in claim 1. Preferred embodiments of the present invention may be gathered from the dependent claim.

    [0022] According to a preferred embodiment, the radial width of the air gap is minimum at the horizontal radial direction which substantially corresponds to the inlet point of the removed material, and it is maximum at the vertical radial direction rotated by 90° with respect to the former one, which substantially corresponds to the outlet point of the removed material.

    [0023] According to the present invention, the curved wall presents a profile which is transversal to the axis of the drum, consisting of an arch of ellipse.

    [0024] According to another arrangement not in accordance with the present invention, the curved wall presents a profile which is transversal to the axis of the drum, consisting of an arch of circumference.

    [0025] Advantageously, the chamber of the present invention allows a better conveyance of the milled material than with the prior art.

    [0026] Still advantageously, as the chamber of the present invention has a greater width in the portion wherein the milled material concentrates, it presents a lower wear.

    [0027] Advantageously, the increase of volume of the air gap at the unload or discharge side decreases the pressure of the material against the curved wall, and makes the expulsion from the chamber faster.

    [0028] Said purposes and advantages shall be illustrated more dearly in the description of a preferred embodiment of the present invention, which is illustrated as a non-limitative indication with reference to the attached drawings, wherein:
    Fig. 1
    shows the cross section of a road scanfier and of the relevant milling drum and containment chamber, according to the prior art;
    Fig. 2
    shows a road scarifier having a containment chamber in accordance with the present invention;
    Fig. 3
    shows an embodiment of the chamber of the present invention in cross section;
    Fig. 4
    shows another chamber in cross section, not in accordance with the present invention.


    [0029] As it can be seen in Fig. 2 and more in detail in Fig. 3, the containment chamber of the present invention, referred to in its entirety with reference numeral 1, houses the milling drum 2 of a road scarifier, referred to in its entirety with M, which comprises a frame 3 mounted on wheels 4, provided with a propulsion unit 5 and a driving seat 6 for the operator.

    [0030] Also, the milling machine 2 is supported by frame 3, and it presents active elements 2a that, during the rotation of the milling drum, come into contact with the surface to be removed which, for example, can be the bitumen road surface 7 which covers a road site.

    [0031] In particular in Fig. 3 it can be noted that chamber 1 is delimited, on its sides, by the side walls of frame 3 of the road scarifier, and on the upper side by a curved wall 8 with its concavity 8a facing the drum 2 and spaced from it's the active elements 2a.

    [0032] According to the present invention, an air gap 9 defined between the curved wall 8 and the active elements 2a of the milling drum 2 presents a variable radial width I for at least a portion of its extension.

    [0033] Thus, in Fig. 3 it can be seen that the radial width I changes from the minimum value a at the horizontal radial direction determined by an axis x, to the maximum value b at the vertical radial direction determined by an axis y, where axes x and y represent a Cartesian reference system having the origin coinciding with the centre O of the milling drum 2.

    [0034] According to the embodiment shown in Fig. 3, the curved surface 8, with reference to the drawn system of axes x, y, presents an ellipse arch profile whose equation, having indicated with a and b the thickness of air gap 9 along the above axes x and y, and with r the radius of the milling drum 2, results as follows:



    [0035] By mathematically defining the ellipse using the thickness increment i =b-a of the air gap 9 along its circumferential extension corresponding to an angle α, the former equation takes on the following form:



    [0036] A variant of the chamber, not in accordance with the present invention, referred to in its entirety with reference numeral 10, is represented in Fig. 4, where it can be seen that it differs from the previous one in that the curved wall 11 which delimits it in its upper side presents a profile shaped as arch of circumference, having radius:


    where:
    • r is the radius of the circle of the milling drum 2;
    • s is the value of the width of air gap 12 at the horizontal radial direction determined by axis x;
    • i represents the value of the displacement along the axis x of centre O' of the circumference with radius R which defines the profile of the curved wall 11, with respect to centre O of the milling drum 2. In this case, the profile of the curved wall 11 with respect to the same reference system of axes x, y is expressed by the equation of the circumference which takes on the following form:



    [0037] The curved wall of the present invention, realised according to the described elliptical profiles, attains the set purposes.


    Claims

    1. Road scarifier (M) comprising a milling drum (2), a containment chamber (1) for the milling drum (2), a frame (3) mounted on wheels (4) and adapted to support said milling drum (2) and provided with a propulsion unit (5) and with a driving seat (6) for the operator, said containment chamber (1) being delimited laterally by body sides of said frame (3) and on the upper side, for at least a portion, by a curved wall (8) with the concavity facing said drum (2) and spaced from active elements (2a) provided on said milling drum (2) for the removal of the road surface, wherein an air gap (9) defined between said curved wall (8) and said active elements (2a) presents a variable radial width (I) for at least a portion of its extension,
    characterized in that said curved wall (8) presents a transverse profile shaped as an arch of an ellipse.
     
    2. Road scarifier (M) according to claim 1, wherein said ellipse is defined with respect to a Cartesian reference system (x, y) having the origin (O) coinciding with the centre of said milling drum (2) and said ellipse being represented by the equation


    wherein:

    a represents the radial width of said air gap (9) measured in horizontal radial direction with respect to the drum (2) according to axis x;

    b represents the radial width of said air gap (9) measured in vertical radial direction with respect to the drum (2) according to axis y; and

    r represents the radius of said drum (2).


     


    Ansprüche

    1. Straßenfräse (M), welche eine Frästrommel (2), eine Eingrenzungs- bzw. Umschließungskammer (1) für die Frästrommel (2), und einen Rahmen (3) aufweist, welcher auf Rädern (4) angebracht ist und in der Lage ist, die Frästrommel (2) zu tragen, und mit einer Antriebseinheit (5) und mit einem Fahrersitz (6) für den Bediener versehen ist, wobei die Eingrenzungskammer (1) seitlich durch Körperseiten des Rahmens (3) begrenzt ist und auf der Oberseite zumindest teilweise durch eine gekrümmte Wand (8) begrenzt ist, wobei die Wölbung bzw. konkave Seite zu der Trommel (2) weist und von aktiven Elementen (2a) beabstandet ist, welche auf der Frästrommel (2) zum Entfernen der Straßenoberfläche vorgesehen sind, wobei ein Luftspalt (9) zwischen der gekrümmten Wand (8) und den aktiven Elementen (2a) eine variable, radiale Breite (I) für mindestens einen Teil seiner Erstreckung besitzt,
    dadurch gekennzeichnet, dass die gekrümmte Wand (8) ein Querprofil besitzt, das in der Form eines Bogens einer Ellipse ausgebildet ist.
     
    2. Straßenfräse (M) gemäß Anspruch 1, wobei die Ellipse mit Bezug auf ein kartesisches Bezugssystem (x, y) definiert ist, dessen Ursprung (O) mit dem Mittelpunkt der Frästrommel (2) zusammenfällt, und wobei die Ellipse durch die folgende Gleichung repräsentiert ist:


    wobei:

    a die radiale Breite des Luftspalts (9) darstellt, und zwar gemessen in einer horizontalen, radialen Richtung bezüglich der Trommel (2) gemäß der Achse x;

    b die radiale Breite des Luftspalt (9) darstellt, und zwar gemessen in der vertikalen, radialen Richtung bezüglich der Trommel (2) gemäß der Achse y; und

    r den Radius der Trommel (2) darstellt.


     


    Revendications

    1. Scarificateur de route (M) comprenant un tambour de fraisage (2), une chambre de protection (1) pour le tambour de fraisage (2), un châssis (3) monté sur des roues (4) et adapté à porter le tambour de fraisage (2) et muni d'un organe de propulsion (5) et d'un siège de conduite (6) pour l'opérateur, la chambre de protection (1) étant délimitée latéralement par des côtés de corps (3) et, du côté supérieur, pour au moins une partie, par une paroi courbe (8) dont la cavité est tournée vers le tambour (2) et espacée des éléments actifs (2a) prévus sur le tambour de fraisage (2) pour l'enlèvement de la surface routière, dans lequel un intervalle vide (9) défini entre la paroi courbe (8) et les éléments actifs (2a) présente une largeur radiale variable (1) sur au moins une partie de son extension,
    caractérisé en ce que la paroi courbe (8) présente un profil transverse en forme d'arc d'ellipse.
     
    2. Scarificateur de route (M) selon la revendication 1, dans lequel l'ellipse est définie par rapport à un système de référence cartésien (x, y) ayant son origine (O) qui coïncide avec le centre du tambour de fraisage (2) et l'ellipse étant représentée par l'équation


    où :

    a représente la largeur radiale de l'intervalle vide (9) mesurée dans la direction radiale horizontale par rapport au tambour (2) selon l'axe x ;

    b représente la largeur radiale de l'intervalle vide (9) mesurée dans la direction radiale verticale par rapport au tambour (2) selon l'axe y ; et

    r représente le rayon du tambour (2).


     




    Drawing