EP2698475B1 - Self-propelled construction machine and method for operating the same - Google Patents

Description

The invention relates to a self-propelled construction machine, in particular road milling machine or surface miner, which has a machine frame and a chassis that has upstanding drives on the ground. Moreover, the invention relates to a method for operating such a construction machine.

Self-propelled construction machines of the above-mentioned type have a working device arranged on the machine frame, which has a working roller to be brought into contact with the ground for processing the soil material. The work roll can be a milling or cutting roll with which, for example, damaged road layers can be removed or minerals can be mined.

In the known road milling machines and surface miners, the work roll is located in a roll housing which is open at the bottom and is closed by a downholder arranged in the working direction in front of the work roll and a scraper arranged behind the roll in the working direction. On at least one side of the roller housing is closed by a extending in the direction of the plate, which is referred to as edge protection.

The machine frame of the known construction machines can be adjusted in height relative to the ground surface, when the machine stands up with the drives on the ground. For this purpose, the known construction machines have a device for adjusting the height of the machine frame, which is controlled by a control unit. Since the working device is arranged on the machine frame, the height of the machine frame and the height of the work roll is adjusted with the height of the machine frame. The working device can additionally be height-adjustable relative to the machine frame.

The height of the machine frame is adjusted during operation of the construction machine such that the milling drum of the working device penetrates into the ground. In this case, if necessary, the hold-down and the scraper and the edge protection in height relative to the machine frame are adjustable. In general, a floating storage of hold-down, scraper or edge protection is provided on the machine frame, so that the height can adjust itself. This ensures that hold-down, scraper and edge protection can follow the terrain surface and the roller housing is always closed down.

To adjust the working depth of the working device, there is the problem that when lowering the machine frame, the work roll does not penetrate quickly enough into the ground. The speed with which the work roll penetrates into the ground depends on the nature of the work roll, the nature of the soil material and the weight of the construction machine. If the work roll does not penetrate the ground fast enough and the machine frame still continues to lower, there is a risk of the work roll penetrating too deeply into the ground. This problem is referred to in practice as "attachment hole".

It can also happen during operation of the construction machine, that the edge protection, scrapers or hold-down, which are suspended in height adjustable mounted on the machine frame or jammed within the respective guide. Lowering the machine frame with jammed edge protectors, scrapers or hold-downs can cause the construction machine to fall jerkily onto the drives or the work roll when the jamming suddenly loosens. This can cause damage, for example, to the work roll or drive train.

From the DE 40 17 107 A1 is a self-propelled construction machine known for open pit mining, which has a working device for the removal of material. The machine frame of the construction machine is supported by caterpillars that are height-adjustable with respect to the machine frame. The position of the caterpillars is detected by sensors. An off Value and control unit adjusts the height of the caterpillars in such a way that a predetermined load distribution is established for the individual caterpillars.

The DE 10 2010 15 173 A1 suggests for a road milling machine, a control or regulation of the lowering speed of the penetrating into the soil material milling drum to protect the drive motor of the milling drum from overuse. With the control or regulation too fast lowering of the milling drum should be prevented.

The invention is based on the object to provide a self-propelled construction machine, in which an uncontrolled lowering of the machine when setting the working depth of the working device is prevented. An object of the invention is also to provide a method for operating a construction machine, with which an uncontrolled lowering of the machine is avoided.

The solution of this object is achieved according to the invention with the features of the independent claims. The subject matters of the dependent claims relate to preferred embodiments of the invention.

The construction machine according to the invention provides an operating mode for adjusting the working depth of the working device, in which the machine frame is lowered. This operating mode is characterized in that although the working device is operated, but the machine is stationary. In this respect, this operating mode is to be distinguished from the operating mode in which the working device is operated for processing the soil material during the advancement of the machine.

The basic principle of the invention is to measure the impact force exerted on the drives by the construction machine to avoid uncontrolled lowering of the construction machine in the operating mode specified above, assuming that the uncontrolled lowering of the construction machine occurs when the drives when lowering do not stand up on the floor.

The machine frame of the construction machine is lowered by moving the drives and the machine frame relative to each other. If the machine frame should be lowered at a speed greater than the speed at which the work roll penetrates the floor, the drives lift off the floor so that the foot force is less than a predetermined limit value based on the foot force the construction machine gets up with the drives on the ground. In practice, as soon as the drives lift off the ground, the impact force immediately drops to zero and control over the lowering process is immediately lost.

In the construction machine according to the invention and the method according to the invention, the lifting of the drives is detected in that the contact force is measured, depending on the contact force on a controlled lowering or a Uncontrolled lowering of the construction machine is closed. In an uncontrolled lowering appropriate action must be taken.

Basically, the raid force can only be measured on one of the drives, on some of the drives or on all height-adjustable drives. Preferably, the contact force is measured on all height-adjustable drives, wherein it is preferably closed on an uncontrolled lowering depending on the contact force when at least one of the drives lifts off the ground.

In the context of the invention, a drive is understood to mean all means with which the construction machine upright rests on the ground. The drives may be wheels or crawlers, for example.

The construction machine according to the invention is characterized by a measuring device which has means for measuring the contact force exerted by the construction machine on at least one of the drives or a correlated physical force with the contact force. The detection of a variable which correlates with the contact force makes it possible in practice to easily acquire the measured values using the means known from the prior art.

In addition, the construction machine according to the invention has an evaluation unit, which generates a signal, hereinafter referred to as control signal, depending on the measured Aufstandskraft or correlating with the Aufstandskraft physical variable in the operating mode of lowering the construction machine, which is an improper, uncontrolled lowering the construction machine signals when the contact force assumes or falls below a predetermined threshold, and / or generates a control signal that signals a controlled lowering of the construction machine when the contact force exceeds a predetermined limit.

In this context, a control signal is understood to be any quantity with which the information of a controlled or uncontrolled lowering can be represented. In a preferred embodiment, electrical signals are used for information transmission, while under an electrical signal both digital and analog signals are understood.

A preferred embodiment of the invention provides that the control unit for height adjustment of the machine frame with the evaluation cooperates such that in the operating mode of lowering the construction machine further lowering of the construction machine is prevented when the control unit receives a control signal of the evaluation unit, which is an uncontrolled lowering the construction machine signals. Alternatively, it is also possible to release the height adjustment only when the control unit receives a control signal of the evaluation unit, which signals a controlled lowering of the construction machine.

A further preferred embodiment provides a signal unit which has an acoustic and / or optical and / or tactile signal generator, wherein the signal unit gives an acoustic and / or optical and / or tactile signal when the signal unit receives a control signal of the evaluation unit Uncontrolled lowering of the construction machine signals. Alternatively, a controlled lowering can be signaled.

The automatic interruption or release of the height adjustment and the signaling of an uncontrolled or controlled lowering can also be combined with each other, so that the machine operator is signaled the intervention in the machine control.

For the invention is irrelevant which parts of the construction machine can be brought in the height adjustment of the machine frame with the ground in contact. In practice, there is a particular danger that the construction machine is parked with the work roll on the ground when the work roll does not penetrate quickly enough when lowering the machine frame in the ground.

But when the work roll is arranged in a downwardly open roll housing, which is closed on at least one side by a height-adjustable edge protection and / or on the front side in the working direction of a height-adjustable hold-down and / or on the rear side in the working direction of a height-adjustable scraper is closed, is also effectively avoided by the method and apparatus of the invention that the construction machine falls on the drives or the work roll when these parts of the working device jam and should solve when lowering the machine frame again.

In the following, embodiments of the invention will be described in more detail with reference to the figures.

Fig. 1

eine Straßenfräsmaschine in der Seitenansicht,

Fig. 2

ein Blockschaltbild der Steuereinheit, Messeinrichtung, Auswerteinheit und Signaleinheit der Straßenfräsmaschine,

Fig. 3

eine stark vereinfachte schematische Darstellung einer Hubsäule und eines Laufwerks der Straßenfräsmaschine, wobei das Laufwerk auf dem Boden aufsteht und

Fig. 4

eine stark vereinfachte schematische Darstellung einer Hubsäule und eines Laufwerks der Straßenfräsmaschine, wobei das Laufwerk von dem Boden abgehoben ist.

Show it:

Fig. 1

a road milling machine in side view,

Fig. 2

a block diagram of the control unit, measuring device, evaluation unit and signal unit of the road milling machine,

Fig. 3

a highly simplified schematic representation of a lifting column and a drive of the road milling machine, the drive stands up on the floor and

Fig. 4

a highly simplified schematic representation of a lifting column and a drive of the road milling machine, the drive is lifted from the ground.

Fig. 1 shows in side view an embodiment of a road milling machine, which is a small milling machine. The road milling machine has a machine frame 1, which is supported by a chassis 2. The chassis 2 has drives 3 comprising a front wheel 3A and two rear wheels 3B. In Fig. 1 Only the right rear wheel 3B can be seen in working direction A. In the case of the known construction machines, the chassis can also have, for example, chain drives instead of wheels.

The milling machine has a working device 4, which is arranged on the machine frame 1. The working device 4 has a work roll, which is a milling drum. In the Fig. 1 Unrecognizable milling drum is arranged in a milling drum housing 6 of the working device. At the left and right in the working direction A, the milling drum housing 6 is closed by an edge guard 7. In Fig. 1 only the right in the direction of A edge protection 7 can be seen. At the front in the working direction A, the milling drum housing 6 is closed by a holding-down device 8 and at the rear side in the working direction A by a scraper 9. Above the Fräswalzengehäuses 6 is the control station 10 of the milling machine with the driver's seat 11 and the control panel 12th

The machine frame 1 of the milling machine is adjustable relative to the surface 13 of the bottom 14 in height. The device 15 for adjusting the height of the machine frame has a left rear working column in the working direction A and right rear lifting column, which carry the machine frame. The left-hand lifting column is attached to the left-hand drive 3 and the right-hand lifting column is attached to the right-hand drive 3. Fig. 1 shows only the right lifting column 16. When the drives 3 get up on the floor 14, the machine frame 1 is raised by retracting and extending the lifting columns 16, which are controlled by a control unit 17. Since the working device 4 is arranged on the machine frame 1, with the height adjustment of the machine frame, the height of the milling drum can be adjusted over the terrain surface. With the height adjustment of the machine frame and the height of the edge protector 7, the blank holder 8 and the scraper 9 is adjusted, which are also arranged on the machine frame. The edge protection, hold-down and scrapers are also in turn adjustable in height relative to the machine frame. The devices for height adjustment of the edge protection, hold - down and scraper, which are in Fig. 1 are not shown, sees a floating position for the edge protection, Downholder and scraper in front, in the edge protection, hold down and scraper float on the floor.

The control unit 17 provides an operating mode in which the machine frame 1 of the milling machine is lowered to set the milling depth. This process is also referred to as "scheduling". The operator can specify this mode of operation, for example by actuating an actuator on the control panel 12, such as a button or switch.

In addition to the control unit 17 for controlling the device 4 for height adjustment of the machine frame with the left and right lifting column 16, the milling machine has a measuring device 18, evaluation unit 22 and signal unit 30 which in Fig. 2 are shown together with the lifting columns 16 in a block diagram. All units can form separate assemblies or be part of the central control of the construction machine.

The lifting columns 16 are hydraulically actuated. The hydraulics are in Fig. 2 not shown. With the control unit 17, the hydraulic lifting columns 16 can be actuated such that the lifting columns are extended and retracted, whereby the machine frame 1 is raised or lowered when the drives 3 stand up on the ground.

The measuring device 18 has means 19 for measuring the contact force exerted by the milling machine on the drives. The rider force measuring means comprises a first left rear drive upright sensor 19A and a right rear drive ridge upright measuring sensor 19B, which will be described below with reference to FIGS FIGS. 3 and 4 will be described in detail.

The measuring device 18 is connected via a data line 20 to the evaluation unit 22, which in turn is connected to a data line 21 to the control unit. The transducers 19A, 19B generate signals depending on the contact force. In the simplest case, the transducers generate a signal when the drive is standing on the floor and no signal when the drive is not standing on the floor or vice versa. However, the transducers can also generate a signal proportional to the magnitude of the impact force, for example an alternating voltage whose amplitude increases with the contact force. The evaluation unit 22 compares the output signals of the first and second transducers 19A, 19B in each case with a limit, which in the simplest case is zero. If the output signal of the first transmitter is zero and / or the output signal of the second transmitter is zero, the evaluation unit 22 generates a control signal, which signals an uncontrolled lowering of the construction machine in which at least one of the two rear drives does not stand on the ground. On the other hand, the evaluation unit 22 does not generate the control signal if the output signal of the first and second transducers is greater than zero, ie both drives stand up on the ground. In this case, the evaluation unit 22 can also generate a second control signal that signals a controlled lowering of the construction machine. However, such a signal evaluation should only be understood as one of several possible embodiments, since the generation of corresponding signals and their evaluation as such belongs to the prior art.

The signal unit 30 has an acoustic and / or optical and / or tactile signal transmitter 20A, 20B, 20C. When the signal unit 30 receives the control signal of the evaluation unit 22 signaling an uncontrolled lowering of the construction machine in the milling depth adjustment mode specified by the operator, the signal unit gives the operator an acoustic and / or optical and / or tactile signal, so that the operator takes appropriate action can initiate to bring the machine back to a controlled state.

By way of example, it is assumed that in the operating mode for adjusting the milling depth, the machine operator lowers the machine frame faster than the milling drum can penetrate the ground. Consequently, at least one of the two drives loses ground contact, so that the evaluation unit 22 generates the control signal, which signals an uncontrolled lowering of the construction machine. This is signaled to the machine operator immediately with the signal unit 30. The machine operator can then enter Re-establish controlled lowering by immediately interrupting the lowering of the machine frame, whereby it can raise the machine frame again, if necessary.

A further embodiment of the invention provides that not only the evaluation unit 22 but also the control unit 17 for adjusting the height of the machine frame 1 receives the control signal signaling an uncontrolled lowering. The control unit 17 is configured such that it prevents or interrupts a height adjustment by the lifting columns 16 after receiving the control signal. Additionally, the signal unit 30 may alert the operator to the automatic correction. After receiving the control signal, the control unit 17 can also undertake further interventions in the machine control in order to bring the machine back into a controlled state, for example lower the drives 3 that have already been lifted for a short distance until the evaluation unit receives a control signal. which signals a controlled lowering. These corrections can be made by the control unit according to a fixed program sequence. This ensures that an uncontrolled lowering is corrected immediately even if the operator does not make a correction manually.

The FIGS. 3 and 4 show in a simplified schematic representation of one of the two rear lifting columns 16 and the associated drive 3, which is a wheel to get up on the floor. The lifting column 16 has a piston / cylinder arrangement 23, which is arranged in an upper and lower guide tube 24, 32 concentrically enclosing the piston / cylinder arrangement 23. The upper guide tube 24 is connected in the region of the lower portion of the machine frame 1, which is shown only hinted. At the top, the upper guide tube 24 is closed by a lid 25 having a bore 26. The piston 23 B of the piston / cylinder assembly 23 has at the top a guide piece 28 which is guided longitudinally displaceably in the bore 26 of the lid 25. With the top of the guide piece 28, a plate 29 is connected, whose diameter is larger than the bore in the lid. Consequently, the cylinder 23A can move up and down in the guide tubes 24, 32 within the predetermined clearance, the size of the Slit 31 between the bottom of the plate 29 and the top of the lid 25 increases or decreases. When the drive 3 rests on the floor 14, the cylinder 23A is supported with its upper side on the underside of the lid 25. Fig. 3 shows the lifting column 16, when the drive 3 rests on the floor 14, while Fig. 4 The lifting column shows when the drive has lost contact with the ground.

In the present embodiment, the transmitter 19 is an example inductive or capacitive proximity switch, which measures the distance between the bottom of the plate 29 and the top of the lid 25. Instead of a proximity switch but also an electrical switching contact may be provided which is closed or opened when a Aufstandskraft is exerted by the construction machine on the drive. The non-play-free mounting of the piston / cylinder arrangement 23 thus allows, together with a distance sensor, a simple and reliable detection of an uncontrolled lowering of the machine.

Claims (12)

1. Self-propelled building machine, in particular a road cutting machine, or a road miner, with
   a machine frame (1) and a chassis (2), comprising running gears (3) resting on the ground,
   at least one working device (4) arranged on the machine frame (1), having a working roller, which is brought into contact with the ground ,
   a device (15) for adjusting the height of the machine frame (1) in relation to the running gears (3) resting on the ground, and
   a control device (17) to control the device (15) for adjusting the height of the machine frame (1),
   whereby the control unit (17) is so constructed that the control unit has an operating mode to adjust the working depth of the working device, in which the device (15) for adjusting the height of the machine frame (1) is so controlled that the machine frame (1) is lowered, whereby the machine is at a standstill although the working device is driven, whereby a measuring device (18) is provided, that comprises means (19) for measuring the weight imposed by the building machine on at least one of the running gears or a physical value correlated to the imposed weight, characterised in that
   an evaluation unit (22) activated by the control unit (17) in the operating mode for lowering the building machine (1), which according to the measured imposed force or to the physical value correlating to the measured imposed force generates a signal indicating an uncontrolled lowering of the building machine, if the imposed force reaches or falls short of a predetermined threshold value and/or generates a signal indicating a controlled lowering of the building machine, if the imposed weight exceeds a predetermined theoretical load.
2. Device according to Claim 1 above, characterised in that the control device (17) in the operating mode for lowering the building machine works in conjunction with the evaluation unit (22) in such a way that when the control unit (17) receives a signal from the evaluation unit (22), indicating an uncontrolled lowering of the building machine, the device (15) for adjusting the height is then activated, thus preventing any further lowering of the machine frame (1).
3. Device according to Claim 1 or 2 above, characterised in that, in the operating mode, the control device (17) works in conjunction with the evaluation unit (22) in such a way that, if the control unit (17) receives a signal from the evaluation unit (22) indicating an uncontrolled lowering of the building machine, the device (15) for adjusting the height is so activated that the machine frame (1) is raised until the control unit (17) received a signal indicating that the lowering is controlled.
4. Device according to any of the preceding claims 1 to 3, characterised in that a signalling unit (30) is provided, which comprises an acoustic, a visual or a tactile signal transmitter (30A, 30B, 30C), whereby the signalling unit (30) receives an acoustic and/or a visual and/or a tactile signal from the evaluation unit (22), indicating an uncontrolled lowering of the building machine.
5. Device according to any of the preceding claims 1 to 4, characterised in that the working roller of the working device (4) is arranged in a roller housing (6) open at the bottom, that is closed on at least one side of a height-adjustable edge protection (7) and/or at the front side in the direction of working (A) by a height-adjustable pressure element (8) and/or at the rear side in the direction of working by a height-adjustable wiper device (9).
6. Device according to any one of the preceding claims 1 to 5, characterised in that the device (15) for adjusting the height of the machine (1) comprises at least one hydraulic lifting column (16), which is attached to a running gear (3) and supports the machine frame (1).
7. Device according to Claim 6 above, characterised in that the lifting column (16) comprises a piston/cylinder arrangement (23), which is arranged in such a way that the piston/cylinder arrangement adopts a first position in which it is supported against a fixed component (25) if the running gear (3) is subjected to an imposed weight and adopts a second position in which the piston/cylinder arrangement (23) is not supported against a fixed component (25) if the running gear is not supported against a fixed component (25) if the running gear is not subjected to an imposed weight, and that the measuring device (18) comprises means (19, 19A, 19B) for measuring a distance between the fixed component and the piston/cylinder arrangement and the piston/cylinder arrangement that is movable within the predetermined amount of play as a value correlated to the imposed weight.
8. Method for operating a self-propelled building machine, especially a road cutting machine or a surface miner, having a machine frame (1) and a chassis (2) that comprises running gears (3) resting on the ground (14) and having at least one working device (4) arranged on the machine frame (1), which is brought into contact with the ground (14), and a control unit, which has an operating mode, in which the machine frame is lowered, to adjust the working depth of the working device, whereby the machine is at a standstill although the working device is driven, whereby in the working mode for lowering the building machine, the weight imposed by the building machine on at least one of the running gears (3) or the physical value correlating to the imposed weight, is measured by a measuring device (18), and characterised in that if the height of the machine frame (1) is adjusted by an evaluation unit (22) connected to the control unit (17), an uncontrolled operating state of the machine frame (1) is indicated if the imposed weight reaches or falls below a predetermined threshold value and/or a controlled operating state is indicated if the imposed weight exceeds a predetermined threshold value.
9. Method according to Claim 8 above, characterised in that in the operating mode for lowering the building machine, if an indication of an uncontrolled operating state is given, any further lowering of the machine frame (1) is prevented.
10. Method according to Claim 9 above, characterised in that in the operating mode for lowering the building machine, if an indication of an uncontrolled operating state, the machine frame (1) is raised until a controlled operating state is indicated.
11. Method according to any of the preceding Claims 8 to 10, characterised in that in the operating mode for lowering the building machine an acoustic and/or a visual and/or a tactile signal is given if an uncontrolled operating state is indicated.
12. Method according to any of the preceding Claims 8 to 11, characterised in that at least one hydraulic column (16) is provided in order to adjust the height of the machine frame, which is attached to a running gear and supports the machine frame, whereby the one piston/cylinder arrangement (23) is arranged in such a way that the piston/cylinder arrangement adopts a first position, in which the piston/cylinder arrangement is supported against a fixed component (25), when the running gear (3) is subjected to an imposed weight and adopts a second position, in which the piston/cylinder arrangement is not supported against a fixed component (25), when the running gear is not subjected to an imposed weight, and that a distance is measured between the fixed component (25) and the piston/cylinder arrangement (23) that is movable within a predetermined play as a value correlating to imposed weight.

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