Machine for paving concrete paths

A machine for paving concrete paths, of the type in which a concrete mix, in a plastic condition, is spread over a certain width, and is then levelled to a certain height. The machine includes a tractor and a levelling section connected to it, wherein the working width of the tractor and levelling section are adjustable and wherein the adjustment of the working width of the tractor is independent of the adjustment of the working width of the levelling section. The tractor is provided with an element whose width is adjustable and which distributes the concrete mix over a certain width and to a certain height.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a machine for paving concrete paths of the type in which a concrete mix, in a plastic condition, is spread over a certain width and is then levelled to a certain height, the machine consisting of a tractor section and a levelling section connected thereto.

2. State of the Prior Art

Such a device is known from WO-A-95/28525.

In this machine of the prior art the tractor section and the levelling section form one whole, the width of which can be adjusted to the width of the concrete path to be paved.

This machine of the prior art has in itself given great satisfaction and is still used to a large extent. Nevertheless there are some problems associated with the use of this machine. A first problem arises because it is always necessary to have space along the concrete path to be paved. This space is not always available due, for example, to the presence of buildings or plants immediately adjacent to the concrete path to be paved. Another difficulty arises when paving larger surfaces such as squares or wider paths. Here the work must always be carried out in such a manner that after a first strip is paved, the second adjacent strip must be temporarily omitted, but the third strip must be started. The second strip cannot then be paved until the first and second strips have sufficiently hardened. This often results in a loss of time due to the hardening time and may make it impossible for the side edge drop-off to be removed. Finally, the machine is difficult to control and drive when paving curves.

SUMMARY OF THE INVENTION

The object of the invention is to provide a machine of the above-mentioned type in which the above drawbacks are avoided.

This object is achieved according to the invention in that the adjustment of the working width of the tractor is independent of the adjustment of the working width of the levelling section.

Because the working width of both sections is made independent of each other, it is possible to make the working width of the tractor smaller than the working width of the levelling section, or vice versa, thus enabling the above-mentioned problems to be avoided or considerably reduced.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown inFIG. 1, the machine according to the invention consists of two sections, tractor section1and levelling section2. Tractor section1is a section that is displaceable by means of two caterpillar mechanisms3,4, whilst levelling section2is a section coupled to the track section that does not have its own driving means but is propelled together with the tractor section. In the following description reference is made to horizontal and vertical directions, horizontal coinciding with the plane of the tread of caterpillar mechanisms3,4, and the vertical plane referring to the plane that is perpendicular to it.

Each caterpillar mechanism3is mounted on two frame plates which lie on both sides of caterpillar mechanism3and are incorporated inside caterpillar track6.FIG. 1only shows frame plate5, the frame plates being mounted on the axles of driving wheel7and tensioning wheel8of caterpillar track6, whilst gauge wheels9are mounted against the underside of frame plates5.

Two vertical columns10,11and12,13respectively are mounted above each caterpillar mechanism3,4. Vertical columns10,11,12,13are identical and only the structure of vertical column10will be described in more detail below.

A bracket (only bracket15is shown inFIG. 1) is fitted to the top of each of the frame plates belonging to caterpillar track3level with column10, each of which brackets supports an axle journal projecting from the caterpillar track (only axle journal16is visible inFIG. 1). A largely U-shaped profile17is mounted on these axle journals16in a downward direction, two flange plates18,19of which profile17extend along both sides of caterpillar track3. In this case flange plate18, which is located on the outside of the machine, is much shorter than the flange plate19. Flange plate18therefore extends to a point just above the level of the axles of driving wheel7and tensioning wheel8of caterpillar mechanism3, whilst flange plate19extends to a point just above the level of the supporting face of caterpillar track6.

A tube end25, which extends vertically upwards, is mounted on web20of profile17. Over tube end25is pushed a tube end26whose inner circumference almost coincides with the outer circumference of tube end25so that the two tube ends are able to slide over each other telescopically.

Inside tube ends25,26pushed over each other is mounted a hydraulic cylinder piston system consisting of a cylinder27whose closed end is articulated to a plate28which seals the top of tube end26, and a piston which is connected by a piston rod29to web20. On plate28a vertical rod30is mounted on the top, a detection system31of which is fitted by means of which the height of system31can be adjusted to external reference systems. Such systems are generally known in this type of machine and will not be described in further detail here. By means of the piston cylinder system27,29it is possible to adjust the height of tube end26relative to tube end25and hence relative to the ground level, wherein this height adjustment can be controlled by means of detection system31.

As already stated, the four columns10,11,12and13are identical and each of the four columns is therefore also provided with a piston cylinder system and means for detecting the height.

As shown inFIG. 2, columns10,11,12and13have a square cross-section. In principle they may assume a different cross-sectional shape, but because a square cross-section is used, where the diagonals of the square are perpendicular and parallel to the direction of movement of the machine, greater stability is obtained during the movement of the machine.

Plates32and33respectively are secured to the sides facing each other on the inner sides of columns10,11and12,13respectively. Plates32and33are in this case welded directly to the diagonals of columns10,11,12and13. Plates34and35respectively are also secured to the sides of columns10,11and12,13respectively, these sides facing away from each other, by welding to the diagonals of columns10,11,12and13. Plates32,33,34and35are rectangular in shape, two edges of each plate lying in a horizontal plane and the other two edges being vertically directed. In this case the upper edges of plates32,34and33,35respectively are connected by means of plates36,37and38,39respectively, both level with columns10,11and12,13respectively. The vertical dimension of plates32and33is greater than that of plates34,35, the lower edge of plates32,33lying approximately at the same height of the as the axles of driving wheels7and running wheels8, whilst the lower edge of plates34and35lies at a certain height above the level of flange plate20. The lower edge of plates34,35is connected by means of horizontal plates40,41to plates32,33, which are therefore parallel to plates36,37,38and39.FIG. 3shows only plates40and41, but similar plates are located level with columns11and13.

Plates36,37,38,39,40and41are all provided with a rectangular recess through which extend columns10,11,12and13, and are in this case connected by welding to tube ends26belonging to these columns so that all plates32,33,34and35follow the movements of tube ends26.

Between plate32and flange plate19is fitted a plate42which is fixedly connected to flange plate19and which extends from the top of caterpillar mechanism3almost to the level of the bottom over which caterpillar track6is displaced. This plate42serves as a lateral limit for the concrete which is poured in front of the machine and is to be processed by the machine into concrete paths so that the machine does not end up directly below caterpillar track6. Plate42extends over the entire length of the tractor section and is also connected to the innermost flanged section of the U-profile which column11supports. Similarly such a plate43is mounted on the side of columns12,13so that on the side of caterpillar mechanism4the concrete is also kept to the side inside the machine.

A U-shaped profile44,45is mounted on each of the inner sides of plates32,33facing towards each other close to the lower edge thereof. U-shaped profiles44,45are secured to plates32with a head end46,47, and the other ends48,49of these profiles, located at a certain distance from each other, the function of which will be explained later. The U-shaped profiles consist of a web44,45, which is horizontally directed, and two flange plates, only the leading flange plates46,47being visible inFIG. 3.

Inside U-shaped profiles44,45is placed a tray60in the shape of a parallelepiped which rests with its bottom plate on flange plates52,53of U-shaped profiles44,45. Two parallel side walls (only side wall62is shown inFIG. 3) bear against the flange plates of U-shaped profiles44,45so that tray60is laterally displaceable relative to the U-shaped profiles which at the same form a guide for tray60.

Flange plates52,53of the U-shaped profiles have horizontal upper edges which lie level with plates40,41and corresponding plates of columns11and13. Parallel side walls62of tray60, on the other hand, have horizontal upper edges which lie at the level of plates36,37,38and39. This means that the tray projects above the U-shaped profiles.

The two other side walls63and64of tray60therefore extend in the direction of movement of the machine. In the tray thus formed is incorporated the hydraulic drive for caterpillar mechanisms3and4, as are the operating and control means59for operating the machine. This will not be described in greater detail because it is clear to the person skilled in the art, without further explanation, how this can be achieved.

Above flange plates44,45and between plates32,33are fitted eight rectangular tubes extend in the horizontal direction and are perpendicular to the plates32,33. One set of tubes has an inside diameter in which the other tubes have a sliding fit. One end of the one set of tubes is connected to plate32, whilst one end of the other tubes is connected to plate33. A system of four tubes that are telescopically displaceable into each other is formed which therefore interconnects plates32and33, the plates nevertheless being free to move in parallel with each other.

A piston cylinder system is installed inside each pair of the telescopic tubes connected between plates32,33, the piston sections of two systems being connected to plate32, whilst the piston sections of two systems being connected to plate33. The cylinder sections of the first two systems, on the other hand, are connected to plate34and the other two cylinder sections are connected to plate35. The piston cylinder systems are double acting, i.e. a hydraulic pressure can be generated on both sides of the piston in order to displace the piston to one or the other side relative to the associated cylinder.

At the height of columns11and13is fitted a second system of tubes81,82which interact telescopically with tubes83and84. Piston cylinder systems are fitted inside tube systems81,83and82,84, these systems consisting of cylinders85and86respectively, and pistons with piston rods87and88respectively. Tubes81,82are also provided with closing plates89and90respectively. The arrangement of the tube systems is such that in one pair of tubes positioned one above the other the piston cylinder system of the uppermost tube system acts on plates32,34, and in the other pair of tubes positioned one above the other the piston cylinder system of the bottommost tube acts on plates33,35and vice versa.

Due to a suitable application of a hydraulic pressure in the piston cylinder systems in the tubes plates32,34and33,35can be moved away from each other and hence also can caterpillar mechanisms3and4, so that tractor section1becomes wider or plates32,34and33,35can be displaced towards each other so that tractor section1becomes narrower. The tractor section can therefore be set in a continuous way to any desired width. During this movement tray60may be displaced inside U-shaped profiles44and45, the bottom face and the leading face being formed by flange plates44,45and side wall62continuing to form an almost closed surface.

Recesses through which tubes72,73and83,84can pass freely movably are installed in side walls63and64of tray60, whilst these side walls can serve as a closing plate for tubes70,71and81,82. Tubes70,71and81,82therefore form one whole.

To provide adequate rigidity, rods90,94are fitted which connect the upper wall of tube70to the upper wall of tube81. A second pair of rods96,97connects the upper wall of tube81to the upper edge of vertical plate98, which forms a rear wall of tray60. Because of this construction spaces are freely maintained between plate98, whose lower edge connects to bottom plate61and side walls62and63, as a result of which the hydraulic pipes from the tray to the various hydraulic units can be guided outside the tray.

Close to the upper end and on the outside of tray60, two piston cylinder systems100,101can be mounted on rear wall98with a vertical action. The piston is in this case located near the upper edge of plate98, whilst the downwardly projecting end of the piston rod is connected to a plate103which is parallel with plate98and can be displaced along the plate by means of the piston cylinder systems100,101.

Plate103has a rectangular shape and is located opposite the bottommost part of plate98. Plate103can be displaced vertically up and down by means of piston cylinder systems100and101, as a result of which the height of plate103can be adjusted and hence also the quantity of concrete which is admitted to the levelling section. U-shaped brackets107are fitted to the outwardly and rearwardly directed wall of the tube ends of columns11and13, which tube end corresponds to tube end16of column10, in which brackets are placed vertically directed rotary shafts108,109, which are connected to one end of a cylinder of a piston cylinder systems110,111having ends of piston rods112,113connected by means of brackets114,115with vertical rotary shafts116,117to a sub-frame118.

Sub-frame118is also connected by means a second pair of piston cylinder systems120,121to the rear ends of plates32,37and33,39respectively. For this purpose a support plate122is secured to the rear ends of plates32,37, and a support plate123is supported to the rear ends of plates33,39, to which support plates are fitted a bracket124and125respectively with horizontal rotary shafts126,127as the fastening point of one of the ends of piston cylinder systems120,121. Support plates122and123may possibly also be secured to plate98.

Sub-frame118consists of a tray in the shape of a parallelepiped, with a horizontal bottom129, a vertical rear wall130, two vertical side walls131,132, and a leading wall133. The connection between leading wall133and side walls131,132is formed by inclined wall sections to which brackets116and117are secured. The second ends of piston cylinder systems120,121are connected to horizontal rotary shafts134,135incorporated in brackets136,137, which are connected to tray118. In this manner sub-frame118is connected in a rigid manner to the caterpillar tracks of tractor section1.

A rectangular tube138is formed against the inside of side wall131, which tube extends in the vertical direction above the height of side wall131. Rectangular tube138lies with a side that is long in cross-section against the inside of side wall131. Square tubes139,140are formed inside tube138against each short side, which tubes also extend in the vertical direction and up to a certain height project above the level of side wall131. The upper ends of tubes139,140are interconnected by means of a bridge141, which supports a vertical rod142on which a system143is positioned for, detecting the height.

Square tubes144,145are incorporated in tubes139and140so that they have a sliding fit, which tubes project downwards outside tubes139,140, with their bottommost ends connected to a sub-frame146which is fitted under sub-frame118and which will be described in greater detail later. Between tubes139,140there is a vertically directed piston cylinder system whose cylinder147is connected to tube138and where the downwardly projecting end of the piston rod is connected to sub-frame146. In this manner the height of sub-frame146, guided through tubes139,140and144,145, can be displaced vertically up and down and can be adjusted to the desired height.

In a comparable manner a rectangular tube148is formed against the inside of side wall132, in which tube two tubes149and150are fitted whose upper ends can be interconnected by means of a bridge which supports a vertical rod on which is positioned a system for detecting the height. Two tubes154and155are incorporated displaceably inside tubes149,150, and are connected with their lower ends to a sub-frame which is comparable to sub-frame146. The movement of this sub-frame is controlled by means of a piston cylinder system157.

Sub-frame146is shown in greater detail inFIG. 4. In practice the other sub-frame connected to side wall132is designed identically but is mirror symmetrical to it.

Sub-frame146consists of a vertical, mainly rectangular side wall160which lies underneath side wall131. A bent plate161is secured to the vertical leading edge of the side wall and the lower wall, the angle between these two edges being rounded, which plate extends from the side wall up to a certain distance inside it. Plate161forms part of the levelling plate, as will be described below. Levelling plates161in the two sub-frames therefore lie opposite each other and together support a central levelling plate which rests on plates161.

Two rectangular tubes163and164are mounted on the central levelling plate, for example by means of welding. These tubes are horizontally directed and are perpendicular to side walls160of sub-frames146. A vertical plate165is secured to one of the vertical walls of tube163, which plate extends close to the upper edge of side wall160. A rectangular tube166is mounted near the upper edge on the other side of plate165relative to tube163, which rectangular tube is orientated in exactly the same direction as tubes163and164. In the same way a tube167is secured to a vertical side wall of tube164, a tube168being mounted near the upper edge of plate160against plate167, which tube lies on the other side of plate167relative to tube164and has the same orientation and construction. The four tubes163,164,166and168are similarly rigidly connected to the central levelling plate.

Rectangular tubes170,171,172and173are each incorporated inside the tubes so that they have a sliding fit, so that tubes170,171,172and173can be displaced horizontally inside tubes163,164,166and168and therefore form telescopic systems. The ends of tubes171and173projecting outside tubes163and168are connected to side wall160of sub-frame146, whilst the ends of tubes170and172projecting outside tubes164and166are connected to the side wall of the other sub-frame.

Two cylinders174,175of two cylinder piston systems are also connected to central levelling plate162, but this connection is not shown in greater detail. The end of piston rod176belonging to cylinder174is connected to side wall160, whilst the end of piston rod177belonging to cylinder175is connected to the side wall of the other sub-frame. It is possible, by means of the cylinder piston systems, to displace the sub-frames146laterally relative to the central section supporting levelling plate162, and the width of levelling can therefore be steplessly adjusted by plates161and the central levelling plate. In this case plates161and the central levelling plate are constructed as described in more detail in the Dutch patent application in the name of the applicant and filed on Dec. 10, 2007. This applies particularly to the trailing end of levelling plates161and the central levelling plate, which are inclined so that the levelling height of plates161and the central levelling plate is the same.

A hinge180, by means of which a finishing plate181is articulated, is mounted on the rear end of the central levelling plate. A number of reinforcing ribs182, which keep plate181very flat, are fitted to the upper side of finishing plate181. The finishing plate serves to correct minor irregularities which cannot be compensated for by the levelling plates, and extends over the maximum width of the machine. In this case finishing plate181is positioned slightly inclined with the leading edge slightly higher than the trailing edge.

In order to retain plate181further in the desired position, a chain or cord183is fitted which is on the one hand secured to the vertical rear edge of side wall160, close to the upper end thereof, and on the other hand to a point184on the finishing plate in the vicinity of the rear end of plate181. The inclination of plate181can be set by adjusting the length of the cord or chain183. On the other hand plate181can be rotated away not only for possible maintenance or cleaning, but also in the event that n unexpected obstacle should be found in the concrete mass.

In order to apply sufficient pressure to the finishing plate181a piston cylinder system185is fitted between on the one hand side wall160and on the other hand plate181. This system is positioned so that it exerts a certain pressure on plate181, but it also enables the plate to be displaced in the presence of obstacles. This is possible by making use of so-called gas springs which allow compression of the gas and therefore turning away of plate181. Instead of gas springs use can also be made of pressure-compensated hydraulic cylinders.

A number of devices are fitted in the space between plates98,103and plates133and the vertical section of plates161,162for homogenizing the concrete before it is levelled by plates161,162.

These devices consist on the one hand of two mixing screws189and190. The mixing screws consist of a shaft191and192respectively, around which a rod193and194respectively is spirally wound. Shafts191and192are on the one hand rotatably mounted against side walls131and132respectively, and on the other hand are secured in brackets against sub-frames146and156. Driving means for the rotary driving of shafts191and192are present but are not shown.

In addition vibrating bars199are fitted. The vibrating bars are bars consisting of a vertically suspended section, which extends to the rear viewed in the direction of movement of the machine. Each vibrating bar199is connected, with the upper end of the vertical section, to a resilient element that is further suspended by means of a bar, not shown, on either levelling walls161or on the central levelling plate. For this purpose collecting tubes are fitted behind the upper edge of those plates, in which tubes these bars can be suspended. At the minimum width of the machine all the vibrating bars will be suspended on levelling plates161. If the machine is made wider, additional vibrating bars can be placed on the central levelling plate. The vibration of these vibrating bars199is obtained by the movement of the machine, but it is also possible to use hydraulically or electrically driven vibrating bars.

The operation of the machine is as follows:

The width of the tractor section and of the levelling section is adjusted according to the width of the concrete path to be paved. The width of the tractor section is adjusted in a continuous way by means of piston systems77,79;78;86,88and85. The width chosen depends on the circumstances. In practice a width will often be chosen that is smaller than the concrete path to be paved since this guarantees a pavement free from obstacles. The height of tray60together with U-shaped profiles44and45is also adjusted. The adjustment is a function of the final desired thickness of the concrete path, as will be described below.

The width of levelling section2is also adjusted in a continuous way and independently from the width of the tractor section by reinforcing piston cylinder systems174,176and175,177. This is adjusted as accurately as possible to the desired width, the particular advantage of the construction according to the invention consisting in the complete symmetry of the adjustment of the width, thereby improving the stability of the machine and quality of the end product. The thickness of the concrete path is also adjusted by means of piston cylinder system147.

After these adjustments have been carried out the machine can be started. For the paving of a concrete path a quantity of concrete is poured in front of the machine, and the machine is then moves forwards and backwards over it. On the one hand plates52,53and62will together push the uppermost part of the deposited concrete mass forwards, whilst on the other hand a quantity will be admitted underneath U-shaped profiles44,45and tray60. This pushing exerts a distributing effect on the concrete mass, so that it will also be spread width-wise. The adjustment of the height of U-shaped profiles44,45and tray60is preferably chosen so that the quantity of concrete admitted is slightly higher than the quantity of concrete required to pave the concrete path. This also has a distributing effect width-wise on the concrete mass and surplus that is admitted is simply pushed forward through the mass of concrete present in front of levelling plates161the central levelling plate. Any deviations in the height of the machine relative to the wearing surface on which the concrete mass has to be spread and levelled can be compensated for by the height determinations and corrective height adjustments of U-shaped profiles44,45and tray60.

The concrete mass then attains the height of plate103, which is adjusted to a height which corresponds very accurately to the quantities of concrete required to pave the concrete path. This can be achieved by continuously adjusting the height of plate103on the basis of a determination of the height of the concrete mass in the space between plate103and plate133. In this space is placed, at a certain height, a height sensor which can be actuated by the concrete mass in this space. When the concrete mass in this space becomes too great, the height of the concrete mass rises and the sensor is actuated, as a result of which plate103is allowed to drop further and the quantity of concrete supplied to the space in which the sensor is placed is reduced. As soon as the height of the concrete mass in the space has dropped below a certain level, the sensor is no longer actuated and plate103will be displaced upwards causing the concrete mass admitted to rise again. The quantity of concrete in the space between plates103and133may therefore be kept almost constant, ensuring a highly uniform layer of concrete during the subsequent levelling of the concrete by means of levelling plates161the central levelling plate. In practice plate103is adjusted to a certain height that corresponds to the expected concrete consumption, and the control system will regulate variations around the adjustment by means of the sensor.

The concrete then passes underneath the levelling section, where the concrete is levelled flat because the end edges of levelling plates161the central levelling plate lie on the same horizontal line. Height variations of the machine can be compensated for by device185, which adapts the height of the levelling plates and compensates for any local irregularities in height. By means of this machine not only is a concrete layer with a constant height applied in one operation, but the concrete mass is homogenised, spread and distributed in a highly efficient manner.

Because the entire machine is only provided with a single caterpillar mechanism, comprising two caterpillar track mechanisms, the machine can easily be additionally adjusted when the concrete path describes a curve. In the embodiment described and illustrated, an additional adjustment of the position of the levelling section can be obtained by correct actuation of piston cylinder systems110,112,120,111,113and121. This should possibly be combined with the readjustment of the position of edge plates202,203by means of piston cylinder systems174,176;175,177. This is an important advantage over the machines of prior art, all of which have a double caterpillar mechanism where such an additional adjustment in curves encounters considerable problems.

FIGS. 5 and 6illustrate the machine in a simplified manner, focusing on the piston cylinder systems110,112,120,111,113and121. As is clear from the drawing figures and the mechanical arrangement that has been described so far, these piston cylinder systems allow the levelling section to not only be moved rearwardly relative to the tractor section (which is illustrated by comparingFIG. 6withFIG. 2, for example), but also allows adjustment when a concrete path is describing a curve. That is, the levelling section can be adjusted relative to the tractor section by the piston cylinder systems110,112,120,111,113and121by, for example, extending piston113and retracting piston112. This allows the levelling section to, for example, describe an angle with respect to the tractor section. It should also be noted that the levelling section, being suspended by the two pairs of piston cylinder systems110,112and120, and111,113and121, with a pair of the piston cylinder systems being fitted on each side, each piston cylinder system forms an angle with a direction of movement of the tractor. As can also be seen fromFIG. 5, piston cylinder systems147at both ends of the paving pan enable further vertical adjustment of the paving pan independently of the tractor section. As a result, the orientation of the levelling section including the paving pan can be independently adjusted with the present invention with respect to the orientation of the tractor, not only in the vertical plane, but also in the horizontal plane.

A different design may be chosen for the additional adjustment of the levelling section in curves, the sub-frame being placed in a slewing ring which is connected, by means of a telescopic system that can be actuated by means of a piston cylinder system, to tray60. Due to the extension and retraction of the telescopic system and the rotation of the slewing ring the levelling section can be kept in the correct orientation and position at all times. This system may provide particular advantages when GPS systems are used.

It is clear that the invention is not limited to the embodiment described and illustrated but that numerous modifications can be made within the scope of the claims.