WO2004030862A1

WO2004030862A1 - Device for egalising floors

Info

Publication number: WO2004030862A1
Application number: PCT/BE2002/000153
Authority: WO
Inventors: Hans Voet
Original assignee: Hans Voet
Priority date: 2002-10-04
Filing date: 2002-10-04
Publication date: 2004-04-15
Also published as: DE60234478D1; EP1549462A1; AU2002349187A1; ATE448906T1; EP1549462B1

Abstract

The present invention relates to a mobile floor levelling vehicle (1) for levelling an undulating floor surface, whereby the floor levelling vehicle comprises a vehicle body (2) with a front side (20), a back side (21 ), a left side (23) and a right side (24); frontside and backside (12, 13) displacement means for moving the vehicle (1); at least one grinding or polishing tool (3) supported by the vehicle body (2), whereby the at least one grinding or polishing tool (3) comprises a driving (5) for rotating the grinding or polishing tool in a direction substantially parallel to the floor surface. The floor levelling vehicle (1) further comprises bulk part removing means (4) for removing at least a bulk part of the undulation, whereby the bulk part removing means (4) are positioned at a position in front of the at least one grinding or polishing tool (3) in longitudinal direction of the levelling vehicle (1 ), whereby the bulk part removing means (4) extend in transversal direction of the vehicle body (2) and are provided to work the undulations in height direction thereof and to break down and remove at least a bulk part of the undulations, and whereby the at least one grinding or polishing tool (3) is provided for smoothening a surface area part after it has been worked by the bulk part removing means (4).

Description

Device for egalisinq floors.

The present invention relates to a movable floor levelling vehicle according to the preamble of the first claim.

The flatness of floors is particularly important in warehouses, where forklift trucks have to pass through small corridors between racks. When the floor of the corridor is not flat in transversal direction of the forklift truck, there is a risk to sideways tilting of the forklift truck such that its upper part may touch the rack or pallet, or any other obstacle, leading to a possible damage to the rack or pallet, or to the goods stacked thereon. Furthermore, undulations extending in longitudinal direction of the corridor involve up and down bouncing of the forklift truck and an unstable movement thereof. It is clear that, in reality, both type of undulations always occur together and adversely affect the displacement of a forklift truck.

Movable floor levelling vehicles with which floors with an uneven surface may be levelled exist in the art. From EP-B-0541657 a movable floor levelling vehicle is known to which a pair of grinding or polishing tools is mounted on opposite sides of the longitudinal axis of the body, the distance between the grinding or polishing tools being variable. Each grinding or polishing tool comprises a grinding head, which is rotatable in a direction parallel to the floor. The floor levelling vehicle disclosed in EP-B-0541657 further comprises a control system for controlling the grinding depth of each grinding or polishing tool with respect to the floor. The control system operates in response to data received in it, which represent the contours of the floor as it is and the desired final contours of the floor and its degree of flatness. The disadvantage of this known movable floor levelling vehicle is that before any floor levelling action can be started, the floor profile must be determined, or in other words, the undulations need to be measured. This is time consuming.

The present invention now meets the needs of providing a floor levelling device with an improved efficiency, in particular a floor levelling device with which the levelling of an undulating floor may be carried out in a faster manner.

This is achieved according to the present invention with the technical features of the characterising part of the first claim. With the floor levelling vehicle of this invention, the time needed for levelling a floor may be reduced from a few days to a few hours. This effect is attributed to the combined action of the bulk part removing means and the at least one grinding or polishing tool. The bulk part removing means first remove the bulk part of the undulation in the moving direction of the vehicle. Due to the nature of this bulk removing action, this may be done within a shortened period of time, for example, by splintering the material forming the undulation into smaller parts. However, the floor surface remaining after having been worked by the bulk part removing means still shows small-scale roughness. This small-sale roughness is then smoothened by the action of the at least one grinding or polishing tool.

In the present invention the basic function of the grinding or polishing tool comprises smoothening of the floor surface worked by the bulk part removing means. By the combined use of the bulk part removing means and the at least one grinding or polishing tool, only a minor part of the material forming the undulation needs to be ground by the at least one grinding or polishing tool and moulded to powder, which is time saving. An analysis of the problems occurring with the prior art device showed the grinding operation to be the time consuming one.

The grinding action of the prior art device comprises rotating the diamond grinding discs in a direction parallel to the floor surface. The removed material is ground into powder, the removed material serving to further grind the remaining part of the undulation from the floor. This way of removing undulations is laborious and time consuming, the action of moulding the removed material to powder requiring a lot of energy. In the device of this invention, the bulk part removing means extend in transversal direction of the vehicle to allow a simultaneous levelling of a floor surface in a transversal and longitudinal direction, or in other words in the moving direction of the levelling vehicle as well as in a direction perpendicular to this moving direction. The device of this invention is suitable for levelling a wide variety of floors which may either be a new floor or an already existing floor.

Preferably, the bulk part removing means and the at least one grinding tool are positioned at a position between the front- and backside displacement means. As such, the length of the levelling vehicle can be kept limited, since the distance taken in longitudinal of the levelling vehicle between the front- and backside displacement means is used to position the bulk part removing means and the grinding or polishing tool.

The bulk part removing means preferably have a width, which is equal to or larger than the distance d₃ in transverse direction of the levelling vehicle between the centres of the backside displacement means in transverse direction of the levelling vehicle. With this feature it is ensured that the backside displacement means, in the preferred embodiment where the bulk part removing means and the at least one grinding tool are positioned between the frontside and backside displacement means, are moved over the surface area part or trace that has been worked by the bulk part removing means and the at least one grinding or polishing tool. This has the advantage that the risk that the backside displacement means would have to take an undulation that had not been worked by the bulk part removing means and the grinding or polishing tool in the course of the levelling operation, may be minimised. In that way, the levelling operation is improved.

The bulk part removing means are preferably positioned at a first distance d-i from the centre of the frontside displacement means and at a second distance d₂ from the centre of backside displacement means, d₁ > d₂. This means that the bulk part removing means and the at least one grinding or polishing tool are positioned shifted towards the rear part of the vehicle. In contrast to the backside displacement means, which are moved over the levelled surface, the frontside displacement means are moved over the original surface that still needs to be treated and which still contains the undulations. The positioning of the bulk part removing means shifted towards the backside of the floor levelling device in the vicinity of the backside displacement means, has the effect that the extent to which the magnitude of the up- and downward movement of the front side of the vehicle is sensed at the height of the bulk part removing means and the at least one grinding or polishing tool may be reduced. As a result, when the frontside displacement means take an undulation, the bulk part removing means and the at least one grinding or polishing tool are at that moment lifted over a distance in height direction which is smaller than the distance over which they would have been lifted in the case the bulk part removing means would have been positioned closer to the front side. Thus, the influence of undulations met by the frontside displacement means to the levelling operation may be minimised, or in other words, the extent to which the undulations are sensed by the bulk part removing means is levelled out. Consequently, the height over which undulations are removed by the bulk part removing means at the time the frontside displacement means take an undulation, is larger than in the case where the bulk part removing means would have been positioned closer to the front side. Or in other words, the amplitude of the undulation arising in the part of the floor worked by the at least one grinding or polishing tool and bulk part removing means at the time the frontside displacement means take an undulation, is not as high as in the case where the at least one grinding or polishing tool/bulk part removing means would be positioned closer to the front of the vehicle. The result is an improved removal of occurring undulations, according to which undulations with a small and middle large wavelength are removed. The undulations with a larger wavelength are however not completely removed: the amplitude or height of these large- wavelength undulations is only levelled out to some extent. Such undulations with a larger wavelength however do not adversely affect the movement of a forklift. This contributes to the faster operation of the floor-levelling device of this invention.

An analysis of the problems associated with driving forklifts over the floor of long, small corridors extending between high side walls such as in warehouses, has revealed that there is no need for the floor to be completely horizontal and levelled out. To prevent unwanted movements of a forklift it is sufficient that the floor is levelled out to the extent it is sensed by the forklift. To minimise tilting of the forklift in cross direction, the height difference between left and right side of the corridors should be minimised. Pitching of a forklift in longitudinal direction of a corridor appears to take place only with floor undulations having short and medium long wavelengths, i.e. undulations having a length of between approximately 1 cm to 4 m in the moving direction of a forklift, i.e. in longitudinal direction of a corridor. Undulations with a longer length do not adversely affect the movement of a forklift, neither do the very small undulations.

The ratio between the first and the second distance d^ may vary within wide ranges, and is preferably between 1 :1 and 40:1. Undulations occurring in a direction perpendicular to the moving direction of a forklift, i.e. in transversal direction of a corridor and of the vehicle, may be removed by the presence of

(a) a sensor for sensing a height difference between the right and left side of the vehicle body, which is positioned in the vicinity of the bulk part removing means;

(b) left and/or right backside displacement means, the position of which is adjustable in height direction of the vehicle in response to a signal received from the sensor, or in other words, the distance of the displacement means with respect to the vehicle body may be adjusted in response to a signal received from the sensor.

These features ensure that the bulk part removing means and the at least one grinding or polishing tool are maintained substantially horizontal in the course of the levelling operation and that an improved levelling in cross direction of the vehicle may be achieved. This can be explained as follows. When the bulk part removing means take a transversally extending undulation, the levelling vehicle will no longer be in a horizontal position and a height difference between the left and right side of the vehicle will be sensed by the sensor positioned in the vicinity of the bulk part removing means. In response to this signal, the distance between the vehicle body and one or more of the backside displacement means will be increased or reduced to maintain the vehicle body as horizontal as possible. It is possible to increase the distance between the vehicle body and the backside displacement means at the lower side of the corridor, or alternatively, to decease the distance between the vehicle body and the backside displacement means at the elevated side of the corridor. Also, both can be done simultaneously. Due to this increasing or decreasing the distance between the vehicle body and one or more of the backside displacement means, the weight of the levelling vehicle will be displaced towards the bulk part removing means at the elevated side of the corridor, and the pressure exerted at the elevated side of the corridor will be larger as compared to the other side. Because of the higher pressure, the height over which the undulation will be removed by the bulk part removing means at this side will be larger as compared to the lower side. In that way a height difference between the left and right track of the vehicle may be minimised. The same applies when the backside displacement means take a transversally extending undulation. However, as the backside displacement means will usually ride in the levelled tracks, only minor corrections are needed to maintain the levelling vehicle substantially horizontal in the direction perpendicular to the moving direction.

Preferably, the bulk part removing means comprise at least one sawing device. However, any other suitable means for removing at least a bulk part of the undulation known to the man in the art may also be used, such as for example a diamond stone capable of splintering the material forming the undulation.

To minimise the effect of undulations sensed by the frontside displacement means to the levelling operation, the frontside displacement means are preferably positioned along the central longitudinal axis of the levelling vehicle. Preferably, also the frontside displacement means have an elongated shape and extend in longitudinal direction of the levelling vehicle.

Preferably, the movement of the levelling vehicle is operated from a position remote from the levelling vehicle. This entails the advantage that the levelling operation can be done in an easier way.

The invention also relates to a method for levelling floors using the floor levelling vehicle as described above. The method comprises breaking down and removing at least a bulk part of the undulations in height direction thereof by the bulk part removing means, and subsequently smoothening the surface area part worked by the bulk part removing means by the at least one grinding or polishing tool.

In a preferred embodiment, the method for levelling floors comprises (a) a first step in which two parallel tracks are levelled by the combined action of the bulk part removing means and the grinding tools during the movement of a levelling vehicle comprising at least one pair grinding tools, whereby the grinding or polishing tools of the at least one pair of grinding tools are positioned at a distance from each other on opposite sides of a central longitudinal axis of the vehicle body, whereby the parallel tracks are levelled by the combined action of the bulk part removing means and the at least one pair of grinding tools, and whereby the backside displacement means are displaced over the surface area part worked by the bulk part removing means and the at least one pair of grinding or polishing tools, and

(b) a second step in which the surface area part in between the two parallel tracks, levelled in the first step, is levelled during the movement of a levelling vehicle wherein the at least one grinding tool is positioned at a position between the right and left backside displacement means, whereby the surface in between the two parallel tracks is levelled by the combined action of the bulk part removing means and the at least one grinding tool, and whereby the backside displacement means are displaced in the two parallel tracks levelled in the first step.

In the latter method of levelling floors, both the frontside and backside displacement means move over substantially the same surface of the corridor in the first and second step of the levelling operation. This feature allows avoiding height differences between the two parallel tracks levelled in the first step and the track in between these two tracks levelled in the second step.

The invention and further preferred embodiments are elucidated in the figures and description of the figures.

Figure 1 shows a schematic side elevational view of a preferred embodiment of the floor levelling vehicle of the present invention.

Figure 2 shows a top view of the floor levelling vehicle of Figure 1. The floor levelling vehicle 1 shown in Figure 1 comprises a vehicle body 2 with a front side 20 and a backside 21. The vehicle body 2 is supported by frontside and backside displacement means 12, resp. 13. The floor levelling vehicle 1 further comprises a pair of grinding or polishing tools 3 mounted in the vicinity of the backside displacement means 13, and a bulk part removing means 4 positioned in front of the grinding or polishing tools 3. The bulk part removing means (4) and the pair of grinding tools (3) are positioned at a position between the frontside and backside displacement means (12, 13). Alternatively, the bulk part removing means 4 and the grinding or polishing tools 3 may be mounted in front of the frontside displacement means 12, whereby the bulk part removing means 4 are positioned in front of the grinding or polishing tools 3.

Preferably, the bulk part removing means 4 extend over a length which is equal to or larger than the distance d₃ in transverse direction of the levelling vehicle 1 between the centres 16 of the backside displacement means 13 positioned on opposite sides of the vehicle body 2. Alternatively, the bulk part removing means 4 may extend over a length smaller than the distance d₃. When, in the latter case, it is desired to level a path having a width equal to or larger than the width of the vehicle body 2, the levelling operation has to be performed in subsequent steps (see below).

Preferably, the bulk part removing means 4 comprise at least one sawing device 4 as is shown in Figure 1. However, any other suitable means for removing at least a bulk part of the undulation known to the man in the art may also be used. The sawing device 4 is preferably located at a first distance di from the centre 22 of the frontside displacement means 12 and at a second distance d₂ from the centre 23 of backside displacement means 13, d-i ≥ d₂. The first distance di between the centre 22 of the frontside displacement means 12 of the vehicle and the sawing device 4 is substantially larger than the second distance d₂ between the centre 23 of the backside displacement means 13 of the vehicle and the sawing device 4. Preferably the ratio of d-i with respect to d₂ varies from 1 :1 to 40:1.

The sawing device 4 used in the device of this invention may be any sawing device known to the man skilled in the art. A preferred sawing device comprises a plurality of substantially circular sawing heads 7, mounted parallel to each other, onto a rotation axis 8. The rotation axis 8 extends in transversal direction of the vehicle body 2. The length of the rotation axis 8 may be smaller, equal or larger than the width of the vehicle body 2. The outer circumference of these sawing heads 7 comprises for instance teeth, or alternatively, small pins. However any other sawing device known to the man skilled in the art may be used with the vehicle of the present invention. It may for instance also be possible to perform the bulk part removing action by a type of grinding stone. It is possible to mount the sawing heads 7 over the entire length of the rotation axis 8, if it is desired to ground one single path smaller, equal or larger than the width of the vehicle body 2. If it is desired to level two narrower parallel tracks, at the left and right side of the vehicle body a number of sawing heads 7 are mounted each time over a length of the rotation axis 8 equal to the desired width of the track. In the latter case, the central part of the rotation axis 8 remains free of sawing heads 7 over a length equal to the desired distance between the two parallel tracks in transverse direction of the vehicle. In an alternative embodiment of the levelling vehicle for levelling two parallel tracks, two transversally extending rotation axes are provided, one on the left and one at right side of the vehicle body 2. Each axis extends over a part of the width of the vehicle body 2. A plurality of circular sawing heads 7 is mounted to both axes. It is evident that any other arrangement of the circular sawing heads 7 on the rotation axis 8 is also possible. It is also possible to add or remove sawing heads 7. In that way it is possible to adjust the width of the path or track to be levelled, and in the case two parallel tracks are levelled, to adjust the distance in between the two parallel tracks. From the above it is clear that the position and the length over which the sawing heads 7 are mounted with respect to the vehicle body 2, will determine the width of the track or tracks that are levelled. The sawing device 4 is provided to remove the bulk of the undulations sensed by it from the floor surface. As the sawing heads 7 are rotated around their axis 8, the material forming the undulation is splintered and in that way removed from the floor surface. The removed material is received in a collector mounted on the vehicle. The floor surface remaining after it has been worked by the sawing heads 7 is uneven, somewhat toothed and needs to be further smoothened. This is done by the pair of grinding or polishing tools 3, which pas over the part of the floor surface that has been previously worked by the sawing heads 7. However if so desired and if the roughness of the floor so requires, two or more sawing devices 4 may be mounted one behind the other in longitudinal direction of the levelling vehicle 2.

The pair of grinding or polishing tools 3 is positioned further to the backside 21 of the vehicle body 2 as compared to the sawing device 4, rearward of the sawing device. As such, they can smoothen the small-scale roughness in the surface remaining from the bulk removing action of the sawing device. The grinding or polishing tool 3 comprises at least one substantially circular grinding head 9 the surface of which extends in a direction substantially parallel to the floor surface to be worked. This grinding head 9 may be a diamond grinding disc. However any other grinding or polishing tool known to the man skilled in the art may be used with the vehicle of the present invention. The grinding or polishing tool 3 may for instance also comprise a type of grinding stone.

As shown in Figure 1 , a grinding or polishing tool 3 is positioned on each side of the vehicle 2, i.e. on the right as well as on the left side of the vehicle, each grinding or polishing tool 3 comprising one grinding head 9. It may however also be possible to have more than one pair of grinding or polishing tools 3 positioned behind each other. The grinding heads 9 of each grinding or polishing tool 3 are mounted to a rotation axis, which extends in height direction of the vehicle 2. The grinding heads 9 are rotated around the rotation axis by a driving (not shown). The diameter of the grinding heads 9 is selected such that at least the width of the floor surface area part worked by the sawing device 4 is smoothened by the grinding heads 9.

If it is desired to level only a small track in the middle of the corridor, there may however be only one grinding or polishing tool 3 which is positioned in the middle of the vehicle body 2 in transverse direction thereof. In this case, the sawing heads 7 are accordingly mounted in the middle with respect to the vehicle body to the rotation axis 8 over a length of the rotation axis equal to the desired width of the track, such that the grinding or polishing tool 3 passes over the surface area part that has been previously worked by the sawing heads 7. Again, the diameter of the grinding head 9 is selected such that at least the width of the floor surface area part worked by the sawing device 4 is smoothened by the grinding head 9 of the grinding tool 3.

The grinding or polishing tool 3 may also comprise two grinding heads 9 supported on both ends of a support arm fixed to the vehicle chassis by means of a rotation axis which extends in height direction of the vehicle

2 (not shown). The support arm is rotationally mounted around this axis to allow a different positioning of the grinding heads in the same horizontal plane with respect to the floor. When the support arm is positioned parallel to the longitudinal axis 10, both grinding heads are in line with respect to each other. In this case, the track grinded by the grinding heads is equal to the width of one grinding head. When, however, the support arm is positioned under an angle with respect to the longitudinal axis 10, such that both grinding heads are in a staggered position with respect to each other in longitudinal direction of the levelling vehicle, a track with a larger width is ground. The angle α under which the support arm is positioned with respect to the longitudinal axis 10 is preferably such that the track that is ground by one grinding head overlaps the track that is ground by the other grinding head over a part of the width of the track.

If it is desired to ground a path equal or larger than the width of the vehicle body 2, it is possible to mount the sawing heads 7 over the entire length of the rotation axis 8 (see above). In some cases, however, when the width of the track to be levelled is too large, the levelling operation may not be done in one single step and has to be performed in two subsequent steps. In the first step of the levelling operation, at the left and right side of the vehicle body a number of sawing heads are mounted to the rotation axis, each time over a certain maximal allowed distance, e.g. 500 mm. A pair of grinding or polishing tools are mounted behind these sawing heads such that they can work the surface of the floor previously worked by the sawing heads. The backside displacement means are in this first step displaced in the tracks worked by bulk part removing means and the pair of grinding or polishing tools. In a second step, the surface area part in between the two levelled parallel tracks needs to be levelled. Thereto, a levelling vehicle is used whereby in the middle with respect to the vehicle body a number of sawing heads are mounted to the rotation axis over the required length for working the floor part in between the previously levelled tracks. Rearward of the sawing device, a grinding or polishing tool is positioned at a position between the left- and right backside displacement means. The backside displacement means are in this second step not displaced over the surface area part worked by the bulk part removing means and the grinding tool levelled in this second step. Instead, they are displaced in the parallel tracks levelled in the first step. Thus, both the frontside as well as the backside displacement means move over substantially the same surface area of the corridor in this second step of the levelling operation as they did in the first step. This feature allows to avoid height differences between the two parallel tracks levelled in the first step and the track in between these two tracks levelled in the second step. As is shown in figure 1 , the frontside displacement means 12 are positioned at the front side 20 of the vehicle body 2. The frontside displacement means 12 preferably have an elongated shape, they are mounted to the central longitudinal axis 10 of the vehicle body 2 and extend in longitudinal direction of the vehicle 2. The central mounting is preferred as this allows simplifying the device. It further allows reducing the influence of undulations occurring in transversal direction of the levelling vehicle 1 to the result of the levelling operation. This allows improving the relative flatness of the floor.

The frontside displacement means 12 are preferably independently suspended to the vehicle body 2.

The frontside displacement 12 means may take different forms, and may for example be an elongated skate which extends in longitudinal direction of the vehicle body 2. The frontside displacement 12 means may also either be one single skate (Figure 1), a cascade of skates mounted the one behind the behind each other in longitudinal direction of the vehicle, two or more co-operating parallel skates, a cascade of such groups of parallel skates, the groups mounted the one behind the other in longitudinal direction of the levelling vehicle. In the latter cases, the moving mechanism may be by a step mechanism. It is also possible to have two parallel rows of skates, whereby each row is on one side of the longitudinal axis 10 of the levelling vehicle and comprises a plurality of skates mounted the one behind the other in longitudinal direction of the levelling vehicle such that the skates of one row are in a staggered position with respect to the skates in the other row. The frontside displacement means 12 may also comprise a single wheel, a cascade of independently suspended wheel pairs in length direction of the vehicle (not shown). Two wheels may be suspended to a first axis, a plurality of such first axis' being suspended to a second axis, the second axis in turn being suspended to the vehicle body 2. The wheels may be used as such or may be surrounded by a rubber track to smoothen their movement when moving over floor undulations. The elongated skate may comprise a sliding strip attached to its bottom face to smoothen its movement, or may comprise a plurality of wheels which extend through a central slit in the bottom face of the skate (Figure 1) that is moving over the floor surface. However, any other displacement means known to the man skilled in the art may be used. Undulations extending in width direction of the vehicle body and undulations in the moving direction always occur together. However, to allow explaining how each type of undulations is removed, they are treated as they would occur separately. The presence of a cascade of wheel pairs or a skate as frontside displacement means allows reducing the magnitude of the up- and downward movement of the front side of the vehicle when taking the undulations in the moving direction of the vehicle at the position of the sawing and grinding means. This has as a result that taken in the moving direction of the vehicle, an improved removal of the material forming the undulations may be achieved, or in other words that the removed height varies within small ranges. As a result a levelled track may be obtained the level of which may contain remaining undulations. The height of these undulations may however be within acceptable dimensions, which are too small to cause pitching of a fork lift truck. The presence of a skate as frontside displacement means allows removing undulations, having short wavelengths in the moving direction. Because of its length, the skate slides over the tops of the undulations and is virtually insensitive to irregularities at small distance from each other. As a result, the up- and downward movements of the front side of the vehicle will be reduced. The amount of up- and downward movements sensed by the sawing device 4 and the at least one grinding or polishing tool 3 will be reduced accordingly. This has the result that, taken in the moving direction of the vehicle, a smoothening of the levelled track is obtained.

The backside displacement means 13 may, similar to the frontside displacement means 12, take different forms. The backside displacement means 13 differ from the frontside displacement means 12 in that they are provided on opposite sides of the vehicle body 2, i.e. the left as well as on the right side of the vehicle body 2. The position and distance between opposite backside displacement means 12 is preferably adjusted such that the backside displacement means are moving in the tracks that have been previously levelled by the sawing heads 7 and the grinding or polishing tools 3. In Figure 1 , on the left and right side of the vehicle body 2 one pair of wheels mounted one behind the other in longitudinal direction of the levelling vehicle is present. Each wheel pair is suspended by a suspension leg 17 to the vehicle. To maintain the grinding area free of ground dust and other debris, clean water is fed from an external source to the sawing and grinding device. Dirty water and debris may be withdrawn from the grinding area by a vacuum pump 24. The levelling vehicle may be provided with a power pack in the form of a diesel engine coupled to a hydraulic pump which powers the hydraulics of the system through a controllable valving arrangement. To the rear of the vehicle, a diesel fuel tank and a hydraulic oil storage tank may be mounted (not shown). The floor levelling device of this invention has features which ensure that the bulk part removing means and the at least one grinding tool are maintained substantially horizontal. This will in general be done in response to a signal received from a sensor, which detects a height difference between the left and right side of the vehicle at the position of the sawing device 4 in case one of these sides takes an undulation. In response to this signal, one or more of the backside displacement means may be sunk or lifted with respect to the vehicle body to maintain the vehicle body as horizontal as possible. This may for example be achieved by means of a hydraulic or electrical mechanism for adjusting the length of the suspension device 17 by which the backside displacement means are suspended to the vehicle 1.

By the fact that the backside displacement means are constructed as a cascade of wheel pairs or a skate, the inclination of the vehicle is reduced when the backside displacement means take an undulation extending in the moving direction of the vehicle that had not been worked by the bulk part removing means and the grinding or polishing tool. As a result, the extent to which this undulation is sensed by the bulk part removing means and the at least one grinding or polishing tool is reduced. Consequently, the bulk part removing means and the at least one grinding or polishing tool are lifted over a distance in height direction that is smaller than the distance over which they would have been lifted in the case where the backside displacement wheels would comprise one single wheel. Consequently, the height over which the floor, passed by the bulk part removing means and the at least one grinding or polishing tool while the front wheels ride over the irregularity, is ground by the bulk part removing means, is larger as in the case where the sawing tools are positioned closer to the front wheels. Or in other words, the amplitude of the undulation arising, i.e. the second undulation, in that part of the floor ground by the at least one grinding or polishing tool/ bulk part removing means at the time the backside displacement means ride over the first irregularity, is not as high as it would have been the case when the backside displacement means would comprise one single wheel, and has a lower amplitude than the first irregularity. As the levelling vehicle proceeds and the rear wheels now arrive at the second undulation, the same applies, and now a third irregularity arises having a smaller amplitude than the second undulation, the latter being already smaller than the first undulation. Thus, in this way, the recurrence of the same undulation in the ground track can be avoided.

The level below the contact surface between the backside displacement means and the floor surface to which the bulk part removing means/grinding or polishing tools level the floor can be adjusted in function of the deepest 'hole' below a certain reference level in the floor. This is termed the 'offset' of the levelling vehicle. The offset can be adjusted by reducing or extending the length of the suspension legs of the backside displacement means, such that the levelling vehicle is situated at a smaller or larger distance to the floor surface. As the bulk part removing means are fixed at the bottom side of the levelling vehicle, the bulk part removing means are consequently pushed to a greater or lesser extent below the contact surface between the backside displacement means and the floor surface. In the case the floor is undulating in a regular way such that the depth of the holes below a certain reference level is more or less the same over the entire floor surface to be levelled, the offset is adjusted only once at the beginning of the levelling operation and kept constant during the levelling operation. When the floor is however undulating in an irregular way such that floor parts with deep holes alternate with floor parts with less deep holes, the offset may be adjusted during the levelling operation. In this way it is prevented that the sawing device grind the floor to an unnecessarily deep level below the contact surface between the backside displacement means and the floor surface at places where this is not required.

The final contour of the floor is determined by the physical relations within the levelling vehicle. This in contrast to the levelling vehicle of the prior art, where the final contour of the floor is pre-determined from the outside. As the contours of the floor to be levelled are detected and worked by the bulk part removing means in the course of the levelling operation, and as the operation of the bulk part removing means is adjusted in response to any detected undulations, there is no need to determine the contours of the floor prior to the levelling operation, which is time saving.

The movement of the levelling vehicle may be operated from a position remote from the vehicle. It may however also be done from the vehicle itself.

In warehouses, at one or both ends of the parallel corridors, a relatively small corridor perpendicular to these parallel corridors is present. The so-called transfer area allows the trucks to transfer from one corridor to another. The floor levelling vehicle as such would be too long to get turned in this space in order to move to another corridor. Thereto, the skate may be lifted from the ground and be pushed backwards in longitudinal direction of the levelling vehicle underneath the vehicle body. Alternatively, the skate is demounted from the levelling vehicle. As a result, the skate now extends away from the vehicle body over only a minor part of its length, thereby reducing the length of the levelling vehicle. At the same time, the castor wheels 19 present at the left and the right side of the skate are extended in height direction. The levelling vehicle now rests upon these castor wheels at the front side and can turn on these wheels.

Claims

1. A mobile floor levelling vehicle (1) for levelling an undulating floor surface, the floor levelling vehicle comprising

- a vehicle body (2) with a front side (20), a back side (21), a left side (23) and a right side (24);

- frontside and backside (12, 13) displacement means for moving the vehicle

(1);

- at least one grinding or polishing tool (3) supported by the vehicle body (2), the at least one grinding or polishing tool (3) comprising a driving (5) for rotating the grinding or polishing tool in a direction substantially parallel to the floor surface, characterised in that the floor levelling vehicle (1 ) further comprises bulk part removing means for removing at least a bulk part of the undulation (4), the bulk part removing means (4) being positioned at a position in front of the at least one grinding or polishing tool (3) in longitudinal direction of the levelling vehicle (1 ), the bulk part removing means (4) extending in transversal direction of the vehicle body

(2) and being provided to work the undulations in height direction thereof and to break down and remove at least a bulk part of the undulations, the at least one grinding or polishing tool (3) being provided for smoothening a surface area part after it has been worked by the bulk part removing means (4). 2. A mobile floor levelling vehicle as claimed in claim

2, characterised in that the bulk part removing means (4) and the at least one grinding tool (3) are positioned at a position between the frontside and backside displacement means (12, 13).

3. A mobile floor levelling vehicle as claimed in claim 2, characterised in that each of the backside displacement means (13) have a centre (16) in transverse direction of the levelling vehicle (1 ) and in that the bulk part removing means (4) have a length which is equal to or larger than the distance d₃ in transverse direction of the levelling vehicle (1) between the centres (16) of the backside displacement means (13) positioned on opposite sides of the vehicle body (2), such that the backside displacement means are displaced over the surface area part worked by the bulk part removing means (4) and the at least one grinding tool (3)

4. A mobile floor levelling vehicle as claimed in claim 2 or 3, characterised in that both the frontside (12) and the backside (13) displacement means (12) have a centre (22, resp. 23) in longitudinal direction of the levelling vehicle, the bulk part removing means (4) being positioned at a first distance d-i from the centre (22) of the frontside displacement means (12) and at a second distance d₂ from the centre (23) of the backside displacement means (13), c ≥ d₂.

5. A mobile floor levelling vehicle as claimed in any one of claims 1 -4, characterized in that the ratio between the first and the second distance d/d₂ is between 1 :1 and 40:1.

6. A mobile floor levelling vehicle as claimed in any one of claims 1 -5, characterised in that the vehicle body (2) comprises a sensor

(6) for sensing a height difference with respect to the floor surface between the right and left side of the vehicle body (2) at the position of the bulk part removing means (4), and in that the position of the left and/or right backside displacement means (13) is adjustable in height direction of the vehicle in response to a signal received from the sensor (6).

7. A mobile floor levelling vehicle as claimed in any one of claims 1 -6, characterised in that the backside displacement means (13) are suspended to the vehicle (1) through a suspension device (17) which is extendible in height direction of the vehicle.

8. A mobile floor levelling vehicle as claimed in any one of claims 1 -7, characterised in that the bulk part removing means (4) and the at least one grinding or polishing tool (3) are adjusted so as to remove an undulation to a level to somewhat below the contact surface between the backside displacement means (13) and the floor surface.

9. A mobile floor levelling vehicle as claimed in any one of claims 1 -8, characterised in that the bulk part removing means (4) comprise at least one sawing device.

10. A mobile floor levelling vehicle as claimed in claim 9, characterised in that the at least one sawing device (4) comprises a plurality of parallel circular sawing heads (7), rotationally mounted on a rotation axis (8) extending in transversal direction of the vehicle body (2).

11. A mobile floor levelling vehicle as claimed in any one of claims 2-10, characterised in that the frontside displacement means (12) are positioned on a central longitudinal axis (10) of the vehicle, have an elongated shape and extend in longitudinal direction of the vehicle.

12. A mobile floor levelling vehicle as claimed in any one of claims 2-11 , characterised in that the front (12) and/or backside (13) displacement means are selected from the group of a sliding skate, rolling wheel pairs, a caterpillar surrounding two or more wheels, a step mechanism or a combination thereof.

13. A mobile floor levelling vehicle as claimed in claim 12, characterized in that the skate comprises a plurality of wheels extending through a series of openings in the bottom face of the skate, or a sliding strip attached to the bottom face of the skate.

14. A mobile floor levelling vehicle as claimed any one of claims 1-13, characterized in that the movement of the levelling vehicle comprises a control system for operating the vehicle from a position remote from the levelling vehicle.

15. A mobile floor levelling vehicle as claimed in claims 1 -14, characterised in that the levelling vehicle comprises at least one pair of grinding or polishing tools (3) supported by the vehicle body (2), the grinding or polishing tools (3) of the pair of grinding tools (3) being positioned at a distance from each other on opposite sides of a central longitudinal axis (a) of the vehicle body (2), the at least one pair of grinding tools (3) being positioned at a position between the frontside and backside displacement means (12, 13), in that the bulk part removing means (4) are positioned at a position between the frontside displacement means and the at least one pair of grinding tools (3), in that the at least one pair of grinding or polishing tools (3) is provided for smoothening a surface area part after it has been worked by the bulk part removing means, and in that the backside displacement means (13) are positioned with respect to the at least one pair of grinding or polishing tools (3) such that they are displaced over the surface area part worked by the at least one pair of grinding or polishing tools (3) and the bulk part removing means (4).

16. A method for levelling a floor using a floor levelling vehicle according to any one of claims 1 -15, characterized in that the method comprises breaking down and removing at least a bulk part of the undulations in height direction thereof by the bulk part removing means (4), and subsequently smoothening the surface area part worked by the bulk part removing means (4) by the at least one grinding or polishing tool (3).

17. A method for levelling a floor according to claim

16, characterized in that the method comprises (c) a first step in which two parallel tracks are levelled by the combined action of the bulk part removing means (4) and the grinding tools (3) during the movement of a levelling vehicle (1 ) comprising at least one pair grinding tools

(3), the grinding or polishing tools (3) of the at least one pair of grinding tools being positioned at a distance from each other on opposite sides of a central longitudinal axis (a) of the vehicle body (2), the parallel tracks being levelled by the combined action of the bulk part removing means (4) and the at least one pair of grinding tools (3), the backside displacement means (13) being displaced over the surface area part worked by the bulk part removing means

(4) and the at least one pair of grinding or polishing tools (3), and (d) a second step in which the surface area part in between the two parallel tracks, levelled in the first step, is levelled during the movement of a levelling vehicle (1) wherein the at least one grinding tool (3) is positioned at a position between the right and left backside displacement means (13), the surface in between the two parallel tracks being levelled by the combined action of the bulk part removing means (4) and the at least one grinding tool (3), the backside displacement means (13) being displaced in the two parallel tracks levelled in the first step.