EP2708650B1 - Self-propelled construction machine and method for controlling a height-adjustable sealing element. - Google Patents

Description

The invention relates to a self-propelled construction machine according to the preamble of claim 1 and to a method for driving a height-adjustable sealing element according to the preamble of claim 18.

With the well-known road milling machines, the road surface can be contoured and just milled. The known road milling machines have a milling device which has a milling drum for milling the material. In a rear-loading road milling machine, the milled material is fed to the following truck via the rear of the milling machine.

Of the road milling machines, the so-called stabilizers or recycler are to be distinguished, which produce by the addition of binders from a non-load bearing ground, such as a loose ground (stabilizer) or a damaged roadway (recycler) a load-bearing substructure, which for later overbuilding with a roadway suitable is.

Road milling machines and stabilizers or recyclers have in common that the working device has a work roll and a roller housing enclosing the work roll, which is closed by at least one working direction downstream of the work roll arranged sealing member, which is also referred to as stripping. In addition to the rear sealing element, road milling machines also have a sealing element arranged in front of the milling drum in the working direction, which is also referred to as a hold-down device. In addition to the hold-down device and the scraper, the road milling machines have a right and left edge protection extending in the working direction, which laterally close the roller housing.

In practice, the problem arises in the case of all sealing elements that the sealing element can hit obstacles in the event of unevenness. Therefore, the sealing element must be adjustable in height. This problem arises in particular in the transverse to the working direction extending front and rear sealing element. The problem of jamming arises in particular in the case of the rear sealing element, since the rear sealing element is set in the working direction and is generally equipped at the lower edge with divorced hard metal elements. This problem is further increased in the rear sealing element in that this sealing element is generally subjected to a pressing force.

A road milling machine with a front hold-down and a rear stripping element is for example from the EP 2 050 875 A2 known. To adjust the height of the hold-down, the road milling machine has a tracking element, with which the hold-down is connected by a control lever so articulated that is lifted when striking the Nachführorgans to an obstacle of hold-down.

The U.S. 4,723,867A describes a road milling machine whose Fräswalzengehäuse has a front and rear sealing element. Both sealing elements can be adjusted in height, so that the milling drum is accessible.

The CN 102 168 401 A describes a self-propelled construction machine, in particular road milling machine, which has a machine frame and a work roll and a roll housing enclosing the work roll, which is closed by at least one sealing element to the ground. In addition, the road milling machine has a device for raising and lowering the sealing element, which has a piston / cylinder arrangement with which the sealing element can be raised or lowered. A control unit regulates the hydraulic pressure in the cylinder of the piston / cylinder arrangement such that the sealing element rests on the ground with a predetermined contact force. For the regulation, the force acting on the sealing element detected vertical force component with a measuring unit that measures the hydraulic pressure in the cylinder. The sealing member is raised when a vertical force acts on the sealing member, so that the hydraulic pressure increases. Thus, the sealing element can be pulled with a certain contact force on the ground lying over the ground (floating position). Although the regulation of the sealing element can react sufficiently, for example, to the change in the milling depth, which leads to a change in the measured hydraulic pressure (vertical force component). The disadvantage, however, is that the control can not respond to obstacles that exert a horizontal force component on the sealing element. When the sealing member abuts an obstacle, its Aufstandskraft with which the sealing member rests on the ground, remains virtually unchanged, since when striking an obstacle only a substantially horizontal force component acts on the sealing member. Consequently, the sealing member is not raised.

From the EP 1 522 634 A2 is a road milling machine with a trained in the manner of a skid seal, which is slidably pulled over the ground, known. The sealing element is pivotally mounted about an axis which lies in the working direction in front of the milling drum. The sealing element can be raised or lowered with a piston / cylinder arrangement. The hydraulic pressure is adjusted so that the sealing member is pivoted against the pavement at a predetermined pressure. If the predetermined pressure between the sealing element and the road surface is exceeded, which is due, for example, to irregularities in the road surface or an increase in the cutting depth, the hydraulic pressure should be designed such that a pivoting back of the sealing element about the axis is made possible. This is to prevent the piston / cylinder arrangement blocking the sealing element.

The invention is based on the object to provide a self-propelled construction machine, in which the roller housing is sealed in the working direction to the front and / or rear and / or side without the risk of blockage by abutting an obstacle sealing element.

The solution of this object is achieved according to the invention with the features of claim 1 and claim 18. The subclaims relate to preferred embodiments of the invention.

The invention relates to a self-propelled construction machine, in particular a road milling machine, a stabilizer or recycler, which has at least one front and / or at least one rear sealing element and / or at least one lateral sealing element.

A sealing element is to be understood as meaning any element with which the roller housing is closed towards the bottom. However, this does not mean that the roll housing is sealed. The respective sealing element or the respective sealing elements is associated with a device for raising and lowering, which is designed such that the sealing element or the sealing elements rest with a predetermined contact force on the ground or pressed onto the ground. In a construction machine with a front and a rear sealing element, for example, two means for raising and lowering are provided.

For the operation principle of the invention is irrelevant how the device is designed to raise and lower the at least one sealing element, as long as the sealing member rests with a predetermined bearing force on the ground when the sealing member is not raised. The bearing force of the sealing element may be the weight of the sealing element. However, the sealing element can be pressed with a bearing force on the ground, which is greater than the weight of the sealing element.

The fiction, contemporary construction machine is characterized in that the means for raising and lowering the sealing member comprises a measuring unit, which is designed such that the measuring unit measures a force acting on the sealing element when abutting the sealing member on an obstacle. In addition, the means for raising and lowering, a control unit, which is designed such that the control unit generates a control signal for lifting the sealing member, when the force component measured with the measuring unit is greater than a predetermined limit, so that the sealing member is raised.

The force measured with the measuring unit is the substantially horizontal component of force acting on the sealing member when striking an obstacle.

The power does not have to be determined absolutely. Rather, it is sufficient if the force is determined quantitatively. Also, the force does not have to be measured directly in its actual physical unit, but can be measured across any physical principles in another physical unit, such as pressure, displacement, or the like, if these physical quantities were easier to detect.

The advantage of the sealing element according to the invention is that obstacles in the working direction of the construction machine can be recognized by the fact that the force acting on the sealing element exceeds a limit value. If this is the case, the sealing element is raised automatically. The sealing element is raised only until the measured force is below the limit again. In this case, it is assumed that the obstacle has been overcome and can be changed back to the original operating mode or a preselected other operating mode. The limit value for the measured force should be such that the sealing element is not raised even at very small forces. When the sealing member is raised, the sealing member may remain in the raised position. For example, the sealing member remains in the raised position when the obstacle is a step. However, the sealing element can also lower again when the obstacle is not a step. When the device for raising and lowering the sealing element has been in the operating mode of the so-called floating position prior to lifting, in which the sealing element is supported on the ground with a predetermined bearing force, the means for raising and lowering the sealing element can, for example, be returned to the Return floating position when the measured force falls below the specified limit again. Then, the sealing element can move automatically down when the height of the terrain decreases, ie the sealing element can then follow the contour of the terrain again. The means for raising and lowering the sealing member may also switch to a preselected other operating mode when the measured force falls below the predetermined limit again, z. B. in an operating mode in which the sealing member is supported by a restoring force is lowered.

In a preferred embodiment, the control unit generates a second control signal when the force is less than the predetermined limit, such that the raising and lowering means switches to an operating mode in which the sealing member can maintain or lower its position. The lowering of the sealing element can be done solely under the action of gravity or be supported by the means for raising and lowering the sealing member with an additional restoring force. The only decisive factor is that the sealing element rests again on the ground with the given contact force.

In a preferred embodiment, the means for raising and lowering the sealing member comprises one or more piston / cylinder assemblies, the cylinder articulated to the machine frame and the piston articulated to the sealing member or its cylinder hinged to the sealing member and the piston articulated to the machine frame are connected. The piston / cylinder arrangement can be operated hydraulically or pneumatically. But it is also an electric motor drive possible. The assemblies required for this purpose belong to the state of the art.

The automatic lifting or lowering of the sealing element relieves the machine operator of the construction machine. Furthermore, the stability of the machine is improved and a constant feed ensured, since there is no risk that the machine breaks loose from obstacles. In addition, the wear of the sealing member is reduced. The control of the sealing element according to the invention can always be in operation during operation of the construction machine or can also be switched off by the operator, so that the raising and lowering of the sealing element can be controlled manually.

A further preferred embodiment of the invention provides a stop element, in particular on the front or rear sealing element, which extends beyond the lower edge of the sealing member downwards. The stop element is preferably a plate-shaped element which extends across the width of the sealing element extends. But it is also possible that the stop element extends only over part of the width of the sealing element.

In a particularly preferred embodiment, in particular of the front or rear sealing member, an upper portion of the stopper member is fixed to the sealing member under a resilient bias, so that the stopper member when striking an obstacle from a first position in which the upper portion of the stopper member to the sealing member is applied, is moved against the resilient bias in a second position in which the upper portion of the stop member projects from the sealing element. The stop element can be guided either linearly guided or pivotally mounted on the sealing element. It is crucial that the stop element changes its position, so that the impact with an obstacle can be detected.

In a further particularly preferred embodiment, the upper portion of the stop element is displaceably guided on an axis which is perpendicular to the plane of the sealing element. However, the stop element can also be guided on an axis extending obliquely to the plane of the sealing element.

The guide of the stop element on the sealing element may comprise at least one guide pin which extends through a bore in the stop element. Preferably, a plurality of guide pins distributed over the width of the sealing element are provided. The guide pin preferably has a screw thread, and the stop element is preferably screwed with a screw, wherein a spring is arranged between the screw and the stop element, so that the stop element is resiliently biased against the sealing element. By turning and loosening the screw, the resilient bias can be adjusted.

The measuring unit has at least one sensor which detects the position of the stop element and which is preferably a distance sensor, with which the deflection or displacement of the stop element when striking an obstacle is detected can. In the simplest case, the distance sensor may be a contact switch, which is actuated by the stop element.

The roller housing is closed in a further preferred embodiment of the invention by two in the working direction of the construction machine behind the work roll rear sealing elements, wherein two means are provided for raising and lowering of the sealing member, so that the two sealing elements are lifted when hitting an obstacle independently can. In this embodiment, the sealing elements may each extend over half the working width of the work roll. Each sealing element is again associated with a stop element which detects the impact force on an obstacle.

The embodiment with two sealing and stop elements has the advantage that when an obstacle occurs, only one of the two sealing elements is lifted, so that the roll housing remains closed on the other side. This is particularly advantageous when cornering the construction machine, in which the risk of striking the outside or inside the curve stop element is at an obstacle.

Hereinafter, an embodiment of the invention will be explained in more detail with reference to the drawings.

Fig. 1

eine erfindungsgemäße selbstfahrende Baumaschine in perspektivischer Darstellung,

Fig.2

eine vereinfachte schematische Darstellung des die Arbeitswalze umschließenden Walzengehäuses der Baumaschine zusammen mit dem Maschinenrahmen, wobei sich ein das Walzengehäuse in Arbeitsrichtung vor der Arbeitswalze verschließendes Abdichtelement in einer ersten Arbeitsposition befindet,

Fig. 3

das Walzengehäuse, wobei sich das vordere Abdichtelement in einer zweiten Arbeitsposition befindet,

Fig. 4

das Walzengehäuse, wobei sich das vordere Abdichtelement in einer dritten Arbeitsposition befindet,

Fig. 5

eine schematische Darstellung des Walzengehäuses zusammen mit der Arbeitswalze, wobei sich das vordere Abdichtelement in einer angehobenen Position befindet,

Fig. 6

eine schematische Darstellung des Walzengehäuses zusammen mit der Arbeitswalze, wobei sich das Abdichtelement in einer abgesenkten Position befindet,

Fig. 7

einen Schnitt durch ein Führungselement und ein Aufnahmeelement der Führung des vorderen Abdichtelements,

Fig. 8

die Vorrichtung zum Anheben und Absenken des vorderen Abdichtelements in schematischer Darstellung,

Fig. 9A

eine schematische Darstellung eines das Walzengehäuse in Arbeitsrichtung hinter der Arbeitswalze verschließenden Abdichtelements und einer Vorrichtung zum Anheben und Absenken des hinteren Abdichtelements, wobei das Abdichtelement auf dem Boden aufliegt,

Fig. 9B

eine schematische Darstellung des hinteren Abdichtelements, wobei das Abdichtelement an einem Hindernis anschlägt,

Fig. 9C

eine schematische Darstellung des hinteren Abdichtelements, wobei das Abdichtelement angehoben ist,

Fig. 10A

eine schematische Darstellung eines das Walzengehäuse seitlich verschließenden Abdichtelements, wobei das Abdichtelement auf dem Boden aufliegt,

Fig. 10B

eine schematische Darstellung des seitlichen Abdichtelements, wobei das Abdichtelement an einem Hindernis anschlägt,

Fig. 11

einen vereinfachten Hydraulikschaltplan, der den Hydraulikzylinder des vorderen oder seitlichen Abdichtelements zeigt,

Fig. 12

einen vereinfachten Hydraulikschaltplan, der den Hydraulikzylinder des hinteren Abdichtelements zeigt,

Fig. 13

die Steuerung für die Einrichtungen zum Anheben und Absenken des vorderen und hinteren Abdichtelements sowie der seitlichen Abdichtelemente in stark vereinfachter Darstellung.

Show it:

Fig. 1

a self-propelled construction machine according to the invention in a perspective view,

Fig.2

a simplified schematic representation of the work roll enclosing roller housing of the construction machine together with the machine frame, wherein a sealing the roller housing in the working direction in front of the work roll sealing element in a first Working position,

Fig. 3

the roller housing, wherein the front sealing element is in a second working position,

Fig. 4

the roller housing, wherein the front sealing element is in a third working position,

Fig. 5

a schematic representation of the roller housing together with the work roll, wherein the front sealing member is in a raised position,

Fig. 6

a schematic representation of the roller housing together with the work roll, wherein the sealing member is in a lowered position,

Fig. 7

a section through a guide element and a receiving element of the guide of the front sealing element,

Fig. 8

the device for raising and lowering the front sealing element in a schematic representation,

Fig. 9A

a schematic representation of the roll housing in the working direction behind the work roll closing sealing element and a device for raising and lowering the rear sealing element, wherein the sealing element rests on the ground,

Fig. 9B

a schematic representation of the rear sealing element, wherein the sealing member abuts an obstacle,

Fig. 9C

a schematic representation of the rear sealing element, wherein the sealing member is raised,

Fig. 10A

a schematic representation of the roller housing laterally sealing element, wherein the sealing element rests on the ground,

Fig. 10B

a schematic representation of the lateral sealing element, wherein the sealing member abuts an obstacle,

Fig. 11

a simplified hydraulic circuit diagram showing the hydraulic cylinder of the front or side sealing element,

Fig. 12

a simplified hydraulic circuit diagram showing the hydraulic cylinder of the rear sealing element,

Fig. 13

the control for the means for raising and lowering the front and rear sealing element and the lateral sealing elements in a greatly simplified representation.

Fig. 1 shows in perspective view as an example of a construction machine, a road milling machine, which is a rear-loading road milling machine. The road milling machine has a machine frame 1, which is supported by a chassis 2. The chassis 2 has a front wheel 2A in the working direction and two rear wheels 2B in the working direction. In the rear area of the machine frame is the driver's station 3. Below the driver's station 3 is the milling device 4 of the road milling machine.

The milling device 4 has a milling drum 5, which is equipped with circumferentially distributed arranged milling chisels 5A. The milling drum 5 is arranged around a transverse axis to the working direction of the milling machine axis of rotation 6 in a Fräswalzengehäuse 7A. The milling drum 5 rotates in the milling drum housing 7A in one predetermined direction of rotation D. In the present embodiment, the milling drum 5 rotates counterclockwise. The housing 7A enclosing the milling drum 5 has an ejection opening on the rear side in the working direction. On the longitudinal sides of the Fräswalzengehäuse is closed by side plates 8. On the milling drum housing 7A is a transport device 9 with a conveyor belt 10 for conveying the milled material, which can be picked up by a truck traveling behind the milling machine.

Hereinafter, the milling drum 5 receiving Fräswalzengehäuse 7 A in detail with reference to the FIGS. 2 to 8 described.

The Fräswalzengehäuse 7 A is a fixed housing part 7 A, which is fixedly connected to the machine frame 1. The fastening elements for the Fräswalzengehäuse 7A are not shown in the figures. In the figures, the milling drum 5 is schematically represented by a cylinder body which encloses the tips of the chisel 5A of the milling drum 5. The milling drum housing 7A extends on both sides beyond the width of the milling drum 5. It surrounds the milling drum 5 except for an opening 11A in the working direction in front of the milling drum and an opening 11B in the working direction behind the milling drum (FIG. Fig. 5 ). The working direction front opening 11A is closed by a sealing element, which is referred to below as hold-down 7B. The rear opening 11 B is closed by a working direction behind the milling drum rear sealing element, which in the FIGS. 1 to 8 but not shown. This sealing element is also referred to as a scraper. In the FIGS. 1 to 8 also the lateral sealing elements are not shown, which are known as edge protection.

Depending on the milling depth of the hold-7B can be adjusted in height. The FIGS. 2 to 4 show how the milling drum dips in the material to be cut in the vertical direction. While the milling drum is immersed in the material, the hold-down of an in Fig. 2 shown in a first position in which the hold-down 7B is fully lowered, moved to a second position in which the hold-down is fully raised ( Fig. 4 ). In this position the maximum depth of cut has been reached.

Fig. 3 shows a middle position of the blank holder 7B at a lower depth of cut. In the present embodiment, the closed Fräswalzengehäuse 7A encloses together with the blank holder 7B, the milling drum 5 over a circumferential angle of about 180 °.

A sectional view show the Figures 5 and 6 wherein the hold-down 7B is in the raised position (FIG. Fig. 5 ) and in the lowered position ( Fig. 6 ) is located. The hold-down 7B closes the working-facing opening between the lower edge 27 of the hold-down 7B and the surface of the pavement 13 to be scoured.

The hold-down 7B has on the outside on both sides of a circumferentially upwardly extending guide rail 15A, 15B. The guide rails 15A and 15B are guided in receiving members 16A and 16B fixed to the machine frame 1. The attachment of the receiving elements is in Fig. 5 or Fig. 6 not shown.

Fig. 7 shows a section through the guide rails 15A, 15B and receiving elements 16A, 16B. The receiving elements 16A, 16B have a U-shaped cross section, in which the guide rails 15A, 15B are guided longitudinally displaceable. Since the receiving elements 16A, 16B engage around the guide rails 15A, 15B, the guide rails are secured in the axial and radial directions. When the hold-down 7B is in the lowered position, the upwardly extending portions of the guide rails 15A, 15B are supported on the milling drum housing 7A. As a result, larger forces can be absorbed.

At the lower edge 27, the hold-down 7B has a sliding member 18 extending along the lower edge, which may be a slide bar. With the sliding member 18 of the hold-7 slides on the surface of the road surface 13. Here, the hold-7B is due solely to its weight on the pavement. When the milling drum 5 is immersed in the road surface in the vertical direction, the hold-down 7B slides upward in the guide.

The road milling machine has a device 19 for raising and lowering the hold-down 7B, which has a piston / cylinder arrangement 20. The piston / cylinder arrangement 20 is operated with a hydraulic unit 21, which is shown only schematically, which supplies the cylinder 20A of the piston / cylinder arrangement 20 with a hydraulic fluid ( Fig. 8 ).

The cylinder 20A of the piston / cylinder assembly 20 is pivotally connected to the machine frame 1 and the piston 20B is pivotally connected to the upper end of a U-shaped profile member 22 fixed to the hold-down 7B. By pressurizing the cylinder 20A with hydraulic fluid, the hold-down 7B can be raised and lowered.

The device 19 for raising and lowering the hold-down 7B further has a control unit 23 and an evaluation unit 24, which are connected to one another via a data line 25. The control unit 23, which is connected to the hydraulic unit 21 via a control line 26, controls the hydraulic unit in such a way that the piston / cylinder arrangement 20 keeps the hold-down 7B pressed onto the ground with a predetermined contact force. For example, the hydraulic unit 21 can release the piston in the cylinder, so that the hold-down 7B rests with its weight on the ground when the hold-down 7B is not lifted when hitting an obstacle.

Moreover, the means 19 for raising and lowering the hold-down 7B has a measuring unit 26 for measuring the force acting on the hold-down 7B when hitting an obstacle. With the measuring unit 26, only the horizontal force component of the force acting on the hold-down force is measured. The evaluation unit 24 compares the measured with the measuring unit 26 stop force with a predetermined limit. When the impact force is larger than the limit value, the control unit 23 generates a first control signal for the hydraulic unit 21 for lifting the hold-down 7B so that the hydraulic unit 21 operates the piston 20B of the piston-cylinder unit 20. The hold down 7B comes with the piston / cylinder unit 20 is raised until the measured impact force is again smaller than the predetermined limit. If the impact force is less than the limit value, the control unit 23 generates a second control signal for the hydraulic unit 21, with which the piston / cylinder assembly 20 is actuated again to lower the hold-down 7B again until the lower edge 27 of the hold-down 7B rests again with the predetermined contact force on the ground, or the hold-down retains its current position, for example when the obstacle is a step. Alternatively, the piston / cylinder assembly 20 also release the hold-down 7B so that the hold-down moves downwardly in the guide due to its weight force or rests on the step with its weight. Since the force acting on the hold-down force is compared with a predetermined limit value, it is precluded that the hold-down height is adjusted even for smaller stops on the material to be cut.

For measuring the impact force, the measuring unit 26 has two sensors 26A, 26B disposed between the receiving members 16A, 16B and the guide rails 15A, 15B in the area where the guide rails extend upwardly beyond the downholder 7B. The sensors 26A, 26B are connected to the evaluation unit 24 via signal lines 26A 'and 26B'. When a substantially horizontal force acts on the hold-down, the ends of the guide rails exert a pressing force on the ends of the receiving elements or within the existing play a slight tilting movement, which is measured by the two sensors 26A, 26B. The evaluation unit 24 evaluates the measurement signals of both sensors. Either only one or the other measuring signal or both measuring signals can be evaluated. For example, an average value of both measurement signals can take place. Suitable pressure measuring sensors and the evaluation of the measuring signals belong to the state of the art. But it is also possible that the sensors are not arranged between receiving elements 16A, 16B and guide rails 15A, 15B, but on the outside of the receiving elements 16A, 16B, to detect the tilting movement of the receiving elements 16A, 16B.

To support the upward movement and to initiate the force when hitting an obstacle, a sliding skid 34 may be provided on the hold-down device, which pushes the hold-down in a stop against an obstacle.

In addition to the above-described means 19 for raising and lowering the front sealing element, the milling machine can also have a device for raising and lowering the in the FIGS. 1 to 8 have not shown rear sealing element or the lateral sealing elements, which has the same structure.

Hereinafter, an alternative embodiment of the means 19 for raising and lowering a sealing member with reference to the FIGS. 9A to 9C described. The sealing element 7A 'can be a stripping element of a milling machine which closes the milling drum housing in the working direction behind the milling drum. However, the sealing element may also be a stripping element of a stabilizer or recycler, which closes the mixing roller housing in the working direction behind the mixing roller. A stabilizer is for example from the EP 1 012 396 B1 known.

When referring to the FIGS. 9A to 9C described embodiment, the parts that the embodiment of the FIGS. 1 to 8 correspond, provided with the same reference numerals.

The sealing member 7A ', which is hereinafter referred to as stripping element is in the FIGS. 9A to 9C shown together with the piston / cylinder assembly 20 only greatly simplified. The device 19 for raising and lowering the stripping element 7A 'comprises the control unit 23, the evaluation unit 24 and the measuring unit 26' and the hydraulic unit 21, which are connected to one another via data and control lines 25, 26.

In the embodiment of the FIGS. 9A to 9C is attached to the plate-shaped stripping element 7A 'a plate-shaped stopper member 28 which may be a metal plate, which preferably extends over the entire width of the stripping element.

The stop element 28 has in the upper region a plurality of mutually spaced holes 29 through which extending at the same intervals guide bolts 30 extend having an external thread 31. The stop element 28 is screwed to the stripping element 7A 'with nuts 33, wherein compression springs 32 are arranged between the stop element 28 and the nuts 33, so that the stop element 28 is resiliently biased against the stripping element 7A'. The guide pins 30 form with the nuts 33 and the springs 32 a linear guide for the stop element 28, so that the stop element 28 from the in Fig. 9A shown position when hitting an obstacle in a working direction A opposite direction can escape.

Fig. 9B shows the moment in which the stopper member 28 abuts an obstacle. When striking the obstacle, the stop element 28 is displaced against the force of the compression springs 31, so that a gap 35 between the stripping and stop element is formed.

The measuring unit 26 'has one or more sensors 26A' spaced apart from each other. The sensors 26A 'are distance sensors that detect when the stopper member 28 is displaced against the direction of travel A to the rear. In this case, the force of the compression springs 32 determines the limit value of the force which must act on an obstacle when the stop element strikes in order to generate a control signal for lifting the stripping element 7A '. The control unit 23 generates a first control signal for the hydraulic unit 21 which actuates the piston / cylinder arrangement 20 at the instant of striking, so that the stripping element 7A 'is raised immediately.

Fig. 9C shows the position in which the lower edge of the stripping element 7A 'is located exactly at the height of the obstacle. At this moment, the compression springs 32 can push the stop element 28 against the stripping element 7A 'again.

When the sensor or sensors 26A 'again recognize that the stop element 28 abuts against the stripping element 7A' ( Fig. 9A ), the control unit 22 generates a second one Control signal for the hydraulic unit 21, so that the piston / cylinder assembly 20 presses the stripping element 7A 'with a predetermined bearing force on the ground.

Over the entire width of the work roll, which may be a milling or mixing roller, can also several, preferably two of the in the FIGS. 9A to 9C be described assemblies arranged side by side. A division of the scraper element into several segments offers advantages, in particular when entering curves, when only one of the two segments has to be lifted.

The automatically height-adjustable sealing element can also be one or both of the lateral sealing elements, which are referred to as edge protection. The Figures 10A and 10B show in a very simplified representation of the left or right edge protection, which extends in the working direction. The edge protector 36 is a plate-shaped element, which is guided easily oscillating in height between lateral stops 37. In the Figures 10A and 10B are the lateral stops 37, which abut on lateral guides 38 of the machine frame, shown only hinted.

The device for raising and lowering the edge protector has a piston / cylinder arrangement 39, which is operated by the hydraulic unit, not shown in the figures, in order to pressurize the cylinder 39A of the piston / cylinder arrangement 39 with a hydraulic fluid. The cylinder 39A of the piston / cylinder assembly 39 is pivotally connected to the machine frame, not shown, and the piston 39B is pivotally connected to the edge protector 36. By applying hydraulic fluid to the cylinder 39A, the edge protector can be raised and lowered.

The edge protector 36 is resiliently biased with a biasing device 40 in the working direction A. The pretensioning device 40 has a guide 41 provided on the edge protection 36 and an element 42 provided on the machine frame, wherein the element 42 provided on the machine frame is guided longitudinally displaceably with the guide 41 in or counter to the working direction A. The edge protector 36 is provided with a Compression spring biased in the working direction, which is supported at one end to the edge protector 36 and the other end to the provided on the machine frame 42 element.

Fig. 10A shows the edge protector 36 in the preloaded initial position before hitting an obstacle. When striking an obstacle, a substantially horizontal force F, which may have a frontal or lateral force component, is exerted on the edge protector. The spring-biased edge protection 36 then deviates counter to the working direction A, so that the compression spring 43 is compressed ( Fig. 10B ). In this case, the edge protector 36 shifts by a certain distance. The displacement by the predetermined distance is detected by a sensor 44, so that a control signal for the hydraulic unit is generated, which actuates the hydraulic cylinder 39 for raising the edge protector. The edge guard 36 is raised until the obstacle is overcome. If the obstacle is overcome, the edge protection pushes back to the starting position due to the restoring force of the compression spring 43, wherein the edge protection is lowered again. In this case, the restoring force of the compression spring 43 determines the impact force at which the edge protection is automatically raised.

Fig. 11 shows a simplified hydraulic circuit diagram showing the hydraulic cylinder 45 for raising or lowering an unillustrated hold-down or edge protection. During the feed of the construction machine, the hold-down or edge protection is in a floating position, so that the hold-down or edge protection rests on the ground with a predetermined contact force. The hydraulic valve 46 of the hydraulic unit connects in the floating position via the cylinder connections connected to the hydraulic lines 47, 48, the upper and lower cylinder chamber 45A and 45B of the hydraulic cylinder 45 for raising and lowering the hold-down or edge protection with a hydraulic tank, not shown, so that the chambers not the system pressure to be applied. The hydraulic valve 46 is a 4/3 way valve. The hydraulic lines leading to the valve are in Fig. 11 for the sake of simplicity not shown. Since no specific hydraulic force acts on the cylinder, the piston can move in the cylinder, so that the Downholder or edge guard moved downwards due to its weight. At the same pressure in both cylinder chambers, this movement can be supported downwards with a corresponding formation of the effective contact surfaces of the hydraulic cylinder, when both chambers are acted upon in the floating position with a pressure, but preferably not equal to the system pressure. By switching the hydraulic valve 46, the one or the other hydraulic line 47 48 can be acted upon by the system pressure (pressure line) or connected to the tank (tank line), so that the piston is moved up or down.

The actuation of the hydraulic valve 46 takes place in dependence on the measured impact force with the control unit, which in Fig. 11 not shown. When hitting an obstacle, the control unit generates a first control signal for driving the hydraulic valve 46, so that the lower cylinder chamber 45B to the pressure line and the upper cylinder chamber 54A are connected to the tank line, whereby the hold-down or edge protection is raised. If the measured force is below the predetermined limit, the control unit generates a second control signal, so that the hydraulic valve 46 is switched back to the floating position, which in Fig. 11 is shown, so that the hold-down or edge protection drops again. An alternative embodiment provides that the hydraulic valve 46 connects the upper cylinder space 45A to the pressure line and the lower cylinder space 45B to the tank line, so that the hold-down or edge protection is pressed down until the hold-down or edge protection impinges on the floor. Only then does the control unit switch the hold-down back into the floating position.

Fig. 12 shows the hydraulic circuit diagram of another embodiment of the hydraulic control. This embodiment differs from the embodiment Fig. 11 in that two cylinder-piston arrangements 49 and 50 are provided for raising and lowering the sealing element, not shown. Another difference lies in an additional hydraulic unit 51 with which a defined pressure force, which is greater than the weight of the sealing element but less than the maximum working force of the respective piston-cylinder arrangement, is exerted on the sealing element. This pressure force, with which the sealing element is pressed onto the ground, proves to be particularly advantageous in a scraper, as a Scraper should remain in contact with the ground even when it is uneven. In the alternative embodiment, the upper cylinder chambers 49A, 50A of the two piston-cylinder assemblies 49, 50 are short-circuited via a first hydraulic line 51 and the lower cylinder chambers 49B, 50B of the piston-cylinder assemblies 49, 50 via a second hydraulic line 52. A third hydraulic line 53 leads from the first hydraulic line 51, and a fourth hydraulic line 54 leads from the second hydraulic line 52 to a hydraulic valve 55. The third hydraulic line 53 with a tank line (not shown) and the fourth hydraulic line 54 with one not connected pressure line connected. For this purpose, the control unit, not shown, actuates the hydraulic valve 55. During the advancement of the construction machine, the ends of the third and fourth hydraulic lines 53, 54 are closed, for which purpose the hydraulic valve in the in Fig. 12 shown position is brought. In this case, the third hydraulic line 53 is connected to the pressure line 56 and the fourth hydraulic line 54 to the tank line 57 of the additional hydraulic unit 51, so that the hold-down is pressed with the predetermined pressure force to the ground. Since the pressing force should be less than the maximum working force of the piston-cylinder assembly, the pressure in the pressure line 56 is less than the system pressure with which the piston-cylinder assemblies are actuated. In the detection of an obstacle, the control unit, not shown again generates a control signal for actuating the hydraulic valve 55 such that the hold-down is raised until the obstacle is overcome.

Fig. 13 shows in a highly simplified schematic representation of an embodiment of the control of an overload protection for a scraper 58, a hold-down 59 and an edge protection 60. The scraper, hold-down or edge protection is assigned in each case a measuring unit 58A, 59A, 60A, each via a signal line 61 with a central control and evaluation unit 65 is connected. The control and evaluation unit 65 controls, via signal lines 62 in response to the impact force measured with the respective measuring unit 58A, 59A, 60A, the hydraulic valve 58B, 59B, 60B associated with the wiper, hold-down or edge protector with which the wiper, hold-down device and edge protector assigned piston-cylinder arrangement is actuated in Fig. 13 not shown. In addition, an operating unit 63 is provided, the is connected via a data line 64 to the control and evaluation unit 65. With the operating unit 63, the operator can turn off the automatic overload protection and adjust the sealing elements 58, 59, 60 by hand in height.

Claims (19)

1. Self-propelled construction machine, in particular road milling machine, recycler or stabiliser, with a machine frame (1) and an operating mechanism (4), wherein the operating mechanism (4) comprises an operating drum (5) and a drum housing surrounding the operating drum (7A), that is closed off to the ground by at least one sealing element (7B; 7A', 36), and at least one mechanism (19) for raising and lowering the at least one sealing element, which is configured so that the sealing element contacts the ground with a predetermined contact force, when the sealing element is not raised,
   characterised in that
   the at least one mechanism (19) for raising and lowering the at least one sealing element (7B, 7A', 36) has a measuring unit (26, 26'), which is configured so that the measuring unit measures a force component acting on the sealing element when it encounters an obstacle, which force component being a substantially horizontal force component, and a control unit (23), which is configured so that the control unit generates a control signal for raising the sealing element when the force component measured by the measuring unit is greater than a predetermined limit value, so that the sealing element is raised.
2. Self-propelled construction machine in accordance with Claim 1, characterised in that the control unit (23) is configured so that the control unit generates a second signal when the force component is less than the predetermined limit value, so that the sealing element maintains its position or can be lowered and then rest on the ground with the predetermined contact force.
3. Self-propelled construction machine in accordance with claim 1 or 2, characterised in that the sealing element is a front sealing element (7B) positioned, when seen in the operating direction of the construction machine, in front of the operating drum (5).
4. Self-propelled construction machine in accordance with Claim 1 or 2, characterised in that the sealing element is a rear sealing element (7A') positioned, when seen in the operating direction of the construction machine, behind the operating drum (5).
5. Self-propelled construction machine in accordance with Claim 1 or 2, characterised in that the sealing element is a lateral sealing element (36) extending in the operating direction of the construction machine.
6. Self-propelled construction machine in accordance with one of the claims 1 to 5, characterised in that the mechanism (19) for raising and lowering the sealing element (7B, 7A', 36) comprises at least one piston/cylinder arrangement (20), wherein the cylinder (20A) has an articulated connection to the machine frame (1) and the piston (20B) has an articulated connection to the sealing element or the cylinder has an articulated connection to the sealing element and the piston has an articulated connection to the machine frame.
7. Self-propelled construction machine in accordance with one of the claims 1 to 6, characterised in that the sealing element (7B, 7A', 36) has at least one impact element (28), which extends downwards over the lower edge of the sealing element.
8. Self-propelled construction machine in accordance with claim 7, characterised in that the impact element (28) is a plate-like impact element.
9. Self-propelled construction machine in accordance with claim 7 or 8, characterised in that an upper part of the impact element (28) is fastened to the sealing element (7B, 7A', 36) under a spring preload, so that, on striking an obstacle, the impact element is displaced against the spring preload from a first position, in which the upper part of the impact element is in contact with the sealing element, into a second position, in which the upper part of the impact element is spaced from the sealing element.
10. Self-propelled construction machine in accordance with claim 9, characterised in that the upper part of the impact element (28) is displaceably guided in a direction opposite to the operating direction of the construction machine.
11. Self-propelled construction machine in accordance with claim 9 or 10, characterised in that the upper part of the impact element (28) is guided displaceably on an axis that is perpendicular to the plane of the sealing element (7B, 7A', 36).
12. Self-propelled construction machine in accordance with one of the claims 7 to 11, characterised in that at least one guide pin (30) is provided on the sealing element (7B, 7A'), which extends through a hole (29) in the impact element (28).
13. Self-propelled construction machine in accordance with claim 12, characterised in that the guide pin (30) has a screw thread (31) and the impact element (28) is screwed on with a screw (33), wherein the spring (32) is positioned between the screw and the impact element.
14. Self-propelled construction machine in accordance with one of the claims 1 to 13, characterised in that the measuring unit (26, 26') has at least one sensor (26A, 26B; 26A') detecting the position of the impact element (28).
15. Self-propelled construction machine in accordance with claim 14, characterised in that the sensor (26A') is a distance sensor, which measures the distance between the sealing element (7A') and the impact element (28).
16. Self-propelled construction machine in accordance with one of the claims 1 to 15, characterised in that the drum housing (7A) is closed off by two rear sealing elements (7A') positioned behind the operating drum when seen in the operating direction of the construction machine, wherein two mechanisms (19) are provided for raising and lowering the sealing element, so that the two sealing elements are raised independently of one another on impact with an obstacle.
17. Self-propelled construction machine in accordance with one of the claims 1 to 16, characterised in that the construction machine is a road milling machine, wherein the operating drum is a milling drum (5).
18. Method for control of a height-adjustable sealing element (7B, 7A', 36), that closes off a drum housing (7A) of a self-propelling construction machine, in particular road milling machine, recycler or stabiliser, from the ground, wherein the sealing element rests on the ground with a predetermined contact force,
    characterised in that
    when the sealing element encounters an obstacle, a force component acting on the sealing element is measured, which force component being a substantially horizontal force component, and the sealing element is raised when the measured force component is greater a predetermined limit value.
19. Method in accordance with claim 18, characterised in that the sealing element is put into an operating mode in which the sealing element can maintain its position or can be lowered when the force component is smaller than the predetermined limit value and then rests on the ground with the predetermined contact force.

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