DE102019214391A1 - Method and control device for a construction machine - Google Patents

Abstract

A method and a control device are provided for a construction machine (1) which has a shovel (5) mounted on a lifting frame (6) for picking up cargo, wheels (3) for moving the construction machine (1) and a drive device (2) for Drive the wheels (3) is provided. The method comprises a heap entry detection step for detecting entry of the shovel (5) of the construction machine (1) into a load heap, at least on the basis of an acceleration gradient which represents a gradient of an acceleration in the direction of travel of the construction machine (1), and a speed gradient which is a gradient a speed of an element of the drive device (2) reproduces. After the entry into the load pile has been detected, a standstill determination step is carried out to detect a standstill of the construction machine (1) with continued wheel movement and, if necessary, the operation of the drive device (2) is intervened.

Description

Technical area

The present invention relates to a method for controlling a construction machine and a control device which is set up to carry out the method. The present invention also relates to a construction machine which is provided with such a control device. In particular, the invention relates to a method for controlling a construction machine, in which special requirements are taken into account when the construction machine enters a load pile.

State of the art

Construction machinery is used regularly with a dynamic mode of operation. In particular in the case of a construction machine that is used for a loading operation, such as a wheel loader, it is customary to drive continuously into a load pile in order to pick up the load with a shovel mounted on the wheel loader and to transport it away. When the construction machine equipped with a shovel is driven into a load pile, special driving dynamics requirements arise during operation of the construction machine.

In particular, when the construction machine enters the load pile, situations occur in which, due to the resistance when driving into the load pile when filling the bucket provided on the construction machine, excessive slip occurs on one or more wheels of the construction machine. If the slip on the wheel or wheels of the construction machine remains undetected for a long period of time, the construction machine and its wheels can dig into the ground. This can cause problems when backing up the construction machine, such as losing the load that was picked up by the construction machine's bucket.

In the prior art according to US 9 555 706 B1 describes a method for controlling a construction machine designed as a wheel loader, in which the wheel slip that occurs when the construction machine enters a load pile is addressed. In the method according to this prior art, various sensor signals are used in order to optimize the operation of the construction machine in the situation mentioned.

Presentation of the invention

The invention addresses the above problem and provides a method for controlling a construction machine. The method can be applied to a construction machine with a shovel mounted on a lifting frame for picking up cargo, wheels for moving the construction machine and a drive device for driving the wheels. The method can have the following steps: a heap entry detection step for detecting an entry of the bucket of the construction machine into a load heap at least on the basis of an acceleration gradient, which represents a gradient of an acceleration in the direction of travel of the construction machine, and a speed gradient, which a gradient of a speed of an element reproduces the drive device; a standstill determination step for detecting a standstill of the construction machine with continued wheel movement, the speed of the construction machine in the direction of movement falling below a predetermined limit value and the wheels of the construction machine continuing to rotate, namely on the basis of a detected acceleration value that reflects an acceleration of the construction machine in the direction of movement, and a Speed value which represents a speed of the element of the drive device; and a state determination step for determining a critical operating state of the construction machine, the critical operating state of the construction machine being determined if the standstill of the construction machine determined in the standstill determination step continues with continued wheel movement for a predetermined period of time after the bucket of the construction machine has entered the load pile in the pile entry recognition step was recognized.

The construction machine can be designed as a wheel loader, which has the lifting frame and the shovel mounted on it. The bucket of the construction machine is mounted on the front side of the construction machine for picking up cargo in such a way that the bucket can assume different positions in relation to the construction machine. The wheels are used to move the construction machine on the ground on which the construction machine is moved. The drive device, which is provided for driving the wheels, can have a drive motor and a transmission with which the drive force generated by the drive motor is transmitted to the wheels.

For the acceleration gradient used in the heap entry detection step, it applies that when the construction machine decelerates, the underlying value of an acceleration of the construction machine is negative. The gradient of the acceleration indicates the slope of the time course with which the acceleration changes. In the present case, it is taken into account that the construction machine is very heavily decelerated when entering a load pile. Since in such a case the acceleration assumes negative values, the gradient of the acceleration also assumes negative values as the deceleration increases.

In the standstill determination step, a standstill of the construction machine with continued wheel movement is detected, whereby the standstill does not have to mean a complete standstill of the construction machine. In the present context, the construction machine can come to a standstill when the speed of the construction machine in the direction of movement falls below a predetermined limit value, that is, if it is still moving slightly. Furthermore, the state of standstill with continued wheel movement means that the construction machine does not move or moves only slightly while one or more of the wheels are still turning. In this situation, one or more wheels can be assumed to be slipping.

This state can be made by detecting the speed of an element of the drive device. An output element of the drive device can serve as an element of the drive device. For example, an output shaft can serve as an element of the drive device in this context, from which a drive force is transmitted directly or indirectly to the wheels of the construction machine.

The critical operating state of the construction machine determined in the state determination step can include the standstill of the construction machine with continued wheel movement, which continues over a predetermined period of time. The predetermined time period can be preset or made variable. The critical operating state of the construction machine can therefore include a state in which one or more wheels of the construction machine are rotated further without the construction machine moving significantly. This condition is to be understood as a critical operating condition of the construction machine, since in this situation the construction machine can dig into the ground with the slipping wheels.

In the pile entry recognition step, a drive torque gradient of the drive device can also be taken into account. The drive torque gradient of the drive device relates to a change in a drive torque of the drive device over time. In the event that the drive torque of the drive device decreases over time, the drive torque gradient is negative. The drive torque can be detected on the element of the drive device on which the speed value is also detected. However, the drive torque can also be detected on another element of the drive device.

The heap entry recognition step can be carried out in a recognition phase which is determined on the basis of temporal gradients of the values taken into account in the heap entry recognition step. The values taken into account in the heap entry recognition step include the acceleration gradient, which is derived from a recorded acceleration measurement value, and the speed gradient, which is derived from a recorded speed value. In addition, the drive torque gradient of the drive device can be used as the value taken into account in the pile entry recognition step in the recognition phase. The recognition phase is a period of time in which the dynamic courses of the values taken into account in the heap entry recognition step are evaluated. The recorded values taken into account in the heap entry detection step and their temporal progressions can be compared with a predetermined characteristic diagram which contains temporal progressions of the corresponding values which are characteristic of a pile entrance of the construction machine. The map can be prepared in advance on the basis of empirical studies. In the characteristics map, predetermined bandwidths can be provided for the temporal progressions of the values, within which the recorded values are expected when entering a pile. The recognition phase is ended when it is determined in the heap entrance recognition step that a heap entrance is present.

In the heap entry detection step, it can be recognized that the bucket of the construction machine has entered the load heap if, due to the deceleration of the construction machine, the acceleration gradient is less than a predetermined acceleration gradient limit value and the speed gradient is less than a predetermined speed gradient limit value. The more the deceleration of the construction machine increases, the lower the acceleration gradient, since it assumes negative values with increasing deceleration. The same applies to the speed gradient, which is lower the more the speed of an element of the drive device is decelerated, since the speed gradient assumes a negative value when decelerated.

In the heap entry detection step, a bucket position value, which is a Indicates orientation of the bucket in relation to the construction machine. It can be provided that the heap entry detection step is only carried out when it is detected that the shovel position value is suitable for entering a load heap. The shovel position of the shovel is only suitable for entering the load pile if the shovel can pierce the load pile when the construction machine moves forward. Thus, on the basis of the shovel position value, it can be taken into account that the orientation of the shovel in relation to the construction machine is such that the shovel can be pierced into the load pile. A mast position value can be taken into account, which takes into account a position of the mast in relation to the construction machine. Since the bucket is mounted on the lifting frame of the construction machine, a lifting frame position value can thus additionally or alternatively be recorded, with which conclusions can be drawn about the orientation of the bucket in relation to the construction machine.

In the standstill determination step it can be determined whether a relation between the detected acceleration value, which represents an acceleration of the construction machine in the direction of movement, and the speed value, which represents a speed of an element of the drive device, is plausible. It can be determined that there is a standstill with continued wheel movement if it is determined that the relation is not plausible. A plausible relationship can be assumed if the movement of the construction machine can be used to infer the movement of the wheel and the movement of the wheel is thus in harmony with the actual movement of the construction machine. If the speed of the element of the drive device, at which the speed of the drive device is detected, has a certain value that would have to lead to a calculable movement of the construction machine in the direction of movement, but this movement is not present, it can be assumed that the relation is not is plausible.

In the standstill determination step it can be determined that there is a standstill with continued wheel movement if the magnitude of the detected acceleration value is less than a predetermined acceleration limit value, while the detected speed value is greater than a speed limit value. In this context, the acceleration value can be taken into account as an amount, so that an assessment can also be made in the event of a fluctuating movement of the construction machine in opposite directions with continued wheel movement. The magnitude of the detected acceleration value is therefore regularly positive and can thus be compared with a positive, predetermined acceleration limit value.

After the critical state of the construction machine has been determined in the state determination step, an operation control step can be carried out in which the drive device of the construction machine is controlled in such a way that the critical state is canceled. The critical state can exist when the construction machine does not move or moves only slightly over a predetermined period of time and the wheels turn at the same time. In this critical condition, the slipping wheels can dig into the ground on which the construction machine is traveling. In order to counteract this critical state, the drive device of the construction machine can thus be controlled accordingly in order to cancel the critical state and in particular any further digging of the slipping wheels.

When the critical state of the construction machine is determined in the state determination step, an operation control step can be carried out in which an output torque of the drive device of the construction machine is reduced. As a result, the rotation of the slipping wheel or wheels in the critical state can be reduced or prevented. The output torque of the drive device can be reduced gradually at a predetermined rate of reduction until the critical state has been eliminated. The output torque of the drive device can alternatively be reduced in steps with predetermined graduated values.

The output torque of the driving device of the construction machine can be kept at the decreased value for a predetermined period of time. In this way, a state can be achieved in which the slipping wheel or wheels can be brought back into engagement with the ground. Said predetermined period of time can be preset or variable. The output torque of the driving device of the construction machine may be increased after being held at the decreased value for a predetermined period of time. The output torque of the drive device of the construction machine can be increased gradually at a predetermined rate of increase until the construction machine starts to move again.

A control device for a construction machine can have an input interface at least for receiving signals from an acceleration sensor for detecting an acceleration of the construction machine and a drive speed sensor for detecting a speed of an element of a drive device of the construction machine. Furthermore, the control device can be provided with an output interface for outputting signals for an intervention in the operation of the drive device of the construction machine. In this case, the control device can be set up to carry out the method with one or more of the features discussed above. The control device can be an independent element that performs the function of the method described above. The control device can also be integrated into a higher-level control device integrated into the construction machine, which controls other functions of the construction machine.

A construction machine can be equipped with a lifting frame, a shovel mounted on the lifting frame for picking up cargo, wheels for moving the construction machine and a drive device for driving the wheels. Furthermore, the construction machine can be equipped with a control device having the features discussed above. In this respect, the construction machine can be put in a position with the control device to carry out the method described above.

To detect a standstill in which the construction machine does not move or only moves slightly, a radar sensor can be used that can determine the speed of the construction machine over the ground. Furthermore, a drive device can be used in the construction machine, the drive force of which is generated by an internal combustion engine and transmitted to the wheels via a transmission. The drive device can additionally or alternatively have an electrical machine for generating the drive force. The drive force generated by the electric machine can be transmitted directly or indirectly to the wheels of the construction machine. The construction machine can be designed as a wheel loader, in which a shovel is attached via a lifting frame to the front side in the direction of travel. However, the construction machine can also take on other designs, such as, for example, the shape of a forklift or a telehandler with a shovel that is mounted on a lifting frame. Other types of construction of the construction machine are also conceivable, as long as they are provided for driving into a load pile and picking up the load accordingly.

Figure list

• 1 shows a schematic representation of a construction machine designed as a wheel loader in an embodiment to which the method can be applied.
• 2 shows, in a schematic view, the time courses of various variables that are characteristic of a wheel loader driving into a load pile.
• 3rd shows schematically functional elements of the method according to an embodiment.
• 4th schematically shows a flow chart of the method of an embodiment.

Detailed description of embodiments

Embodiments of the present invention will be described below with reference to the drawings. First, the structure of the construction machine to which the invention is applicable will be discussed.

In the present embodiment, the construction machine is a wheel loader 1 executed as in 1 is recognizable. The in 1 shown wheel loader 1 has a drive source at its rear portion 2 on. The drive source 2 is designed in the present embodiment as an internal combustion engine with a transmission connected to it. An output element of the transmission of the drive source 2 is with wheels 3rd the construction machine 1 coupled to drive them accordingly. In the present embodiment, all four wheels are 3rd of the wheel loader 1 driven. Corresponding longitudinal and transverse differentials are provided for this purpose. Due to the arrangement of the drive train with longitudinal and transverse differentials, the wheels 3rd rotate at different speeds, which is particularly useful when cornering.

The in 1 shown wheel loader 1 also has a shovel 5 on its front section. The shovel 5 is via a mast 6th with a front frame section of the wheel loader 1 connected. The mast can be pivoted by a hydraulic actuator so that the on the mast 6th mounted shovel 5 can be raised and lowered. The shovel 5 is in turn pivotable on the lifting frame via a hydraulic actuator 6th mounted so that the shovel 5 relative to the mast 6th can be swiveled. In connection with the mast 6th is a mast position sensor 8th provided, which emits a signal as the mast position value HP the lifting position of the mast 6th indicates. It is also related to the shovel 5 a bucket orientation sensor 9 provided, which is in the form of a blade position value SP emits a signal that the position or orientation of the bucket 5 regarding the mast 6th indicates.

The in 1 shown wheel loader 1 also has an acceleration sensor 7th on, which is firmly attached to the frame of the wheel loader 1 is mounted. The accelerometer 7th emits a signal in the form of an acceleration reading a those on the wheel loader 1 indicates effective acceleration. Here is the accelerometer 7th designed as a three-axis acceleration sensor so that it can detect the acceleration in all three axes. In particular, there is the acceleration sensor 7th a signal indicating the acceleration of the wheel loader 1 in the direction of movement, namely in the forward and backward direction. In addition, the in 1 shown wheel loader 1 an input speed sensor 10 intended. This drive speed sensor 10 is in the present embodiment on an output element of the drive device 2 , in particular on an output shaft of a transmission of the drive device 2 intended. The drive speed sensor 10 is mounted in such a way that by detecting the drive speed on the output element of the drive device 2 directly on the rotation of the wheels 3rd can be closed.

The in 1 shown wheel loader 1 also has a control device 4th on. The control device 4th has, in a known manner, a processing device, a memory device and input and output interfaces. Accelerometer signals 7th , the mast position sensor 8th , the bucket orientation sensor 9 and the input speed sensor 10 are via the input interface of the control device 4th fed. The output interface of the control device 4th is with control elements of the drive device 2 connected. In this way, the control device 4th on the operating state of the drive device 2 Exert influence. In particular, the control device 4th the speed, the output torque and thus the power of the drive source 2 influence.

From the accelerometer 7th becomes an acceleration reading a submitted. This acceleration reading a is in the control device 4th into an acceleration gradient there transformed. The drive speed sensor gives a speed value rpm from, which is the speed of the output element of the drive device 2 represents. The speed value rpm is in the control device 4th into a speed gradient drpm transformed.

The mast position sensor 8th generates a mast position value HP , which is the lifting position of the mast 6th and the bucket orientation sensor 9 generates a blade position value SP showing the position of the bucket in relation to the mast 6th indicates. Mast position value HP and blade position value SP indicate whether the shovel 5 of the wheel loader 1 is in a position in which the bucket 5 into one in front of the wheel loader 1 can drive in the load pile. The control device 4th evaluates the mast position value HP and blade position value SP out to determine if the shovel 5 is in a position in which it can be retracted into the cargo heap.

In the storage device of the control device 4th are an acceleration limit a (max) , a speed limit rpm (max) , an acceleration gradient limit there (max) as well as a speed gradient limit value drpm (max) saved. The above values are appropriately preset to be used for the method described below.

One embodiment of the method is explained below. First of all, the relationship between the various measured variables on the wheel loader 1 are recorded, for an exemplary retraction of the wheel loader 1 declared in a cargo heap. 2 shows an example of the course of various variables associated with the entry of the shovel 5 of the wheel loader 1 be recorded in a cargo heap.

In 2 is shown that before the exemplary entry of the wheel loader 1 in the cargo heap, the relevant values are essentially constant, while after entry into the cargo heap I. strong temporal fluctuations result. Specifically, the drive torque value increases T when entering a pile starting from the previous value and then falls due to the unloading of the drive II when the wheels slip, as in section a ) in 2 is shown. The speed value rpm is constant before entering the heap and drops sharply when entering the heap, only to rise again, as in section b) in 2 is shown. The speed value rpm increases again over the course of time as the wheels spin III . The acceleration reading a is constant in front of the pile entrance and has a small positive value, as in section c) of 2 is shown, which indicates an increase in speed in front of the pile entrance. When entering a pile, the measured acceleration value falls a strongly, which results from the strong delay when entering the load pile. The acceleration reading a then increases again to zero, since when the wheel loader is at a standstill, the acceleration accordingly assumes a value of zero. The mast position value HP and the blade position value SP take a position in front of the pile entrance for piercing the shovel 5 is suitable in the cargo piles, as in sections d) and e) of 2 is removable.

In the following, the relationship between the various sizes when entering the heap and their effect on the operation of the wheel laser is shown 1 explained. When entering the pile, the shovel lifts itself 5 against the load, which thus exerts a force on the shovel 5 exercises the direction of movement of the wheel loader 1 counteracts. For this reason, the drive torque value increases T briefly on. The speed value falls in the same context rpm as the wheel loader slows down significantly. This slowdown is reflected in the negative acceleration reading a . Once the wheels 3rd are no longer able to use the driving force of the drive device 2 To transfer them to the ground, these slip and turn without the wheel loader 1 moves forward. By the continued turning of the wheels 3rd without moving the wheel loader 1 dig the wheels 3rd into the ground, which has serious adverse effects on the continued operation of the wheel loader 1 Has. In particular, there is a risk that the wheel loader can no longer free itself from the depressions that have been created. On the other hand, due to the depressions created when reversing the wheel loader 1 Load from the shovel 5 get lost.

In this situation, namely when the wheels are spinning 3rd without moving the wheel loader forward 1 , becomes the drive device 2 relieved so that the drive torque value T decreases again after the increase. The speed value rpm increases again after the reduction, because the slipping wheels from the drive device 2 can be rotated freely. In this situation is the speed of movement of the wheel loader 1 practically zero, which also gives an acceleration reading a results from zero.

For the earliest possible detection of the pile entrance IV of the wheel loader 1 and to remedy a critical state in which the wheels can dig into the ground when the wheel loader is stationary, the in 4th illustrated method performed. This procedure is used when operating the wheel loader 1 carried out continuously and cyclically. The specific contents of the in 4th illustrated steps S1-S4 are in 3rd specified.

As in 4th is shown the procedure in step S1 started. As in detail in 3rd shown is in this step S1 the acceleration gradient there from the measured acceleration value a determined and with the stored acceleration gradient limit value there (max) compared. Furthermore, in step S1 that from the recorded speed value rpm certain speed gradient drpm with the speed gradient limit value drpm (max) compared. In addition, the mast position value HP and the blade position value SP recorded and assessed. In the event that the recorded acceleration gradient there due to the heavy deceleration of the wheel loader 1 less than the acceleration gradient limit there (max) and the detected speed gradient drpm less than a predetermined speed gradient limit drpm (max) is assumed that the wheel loader 1 enters a cargo port. If, in addition, the condition is met that the shovel 5 is in a suitable position for driving into a load pile, what from the mast position value HP and the blade position value SP can be determined in this situation there be closed up that a pile entrance of the wheel loader 1 he follows.

Once in step S1 it is recognized that a pile entrance of the wheel loader 1 occurs, the in 4th shown step S2 executed in order to determine a standstill. In step S2 becomes the acceleration reading a with the acceleration limit a (max) compared. Furthermore, the detected speed value is rpm of the output element of the drive device 2 with the speed limit rpm (max) compared. In the event that the amount of the detected acceleration value a less than a predetermined acceleration limit value a (max) and the detected speed value rpm greater than a speed limit rpm (max) is, the wheel loader comes to a standstill 1 closed with continued wheel movement. Here are the values of the acceleration limit a (max) and the speed limit value rp (max) set up so that a plausibility check between the speed of the output element of the drive device 2 and the actual movement of the wheel loader 1 can be made. As soon as the speed of the output element of the drive device 2 that the wheels 3rd drives, is known, an expected speed of movement of the wheel loader can be determined on this basis 1 calculate. Is due to the acquisition of the acceleration reading a such movement of the wheel loader 1 not before that in accordance with the detected speed of the output element of the drive device 2 can cause the wheel loader to come to a standstill 1 be closed with continued wheel movement.

In this context, the amount of the detected acceleration value a used to ensure minor movements of the wheel loader 1 in forward and reverse direction with slipping wheels 3rd with the acceleration limit a (max) can be compared. Because with a forward and backward rocking movement of the wheel loader 1 this only results in a positive value from the measured acceleration value a , with which a standstill or only a slight movement can be concluded.

After thus in step S1 the entrance of the wheel loader 1 in a cargo heap IV was recognized and in this episode in step S2 the determination of the standstill of the wheel loader 1 with continued wheel movement is made in step S3 Finally, it determines whether the wheel loader is in a critical operating condition 1 is present. An evaluation of the load is sometimes carried out for this V of the drive, i.e. the drive device 2 . In step S3 it is checked whether the wheel loader has come to a standstill 1 continues with continued wheel movement for a predetermined period of time. When the wheel loader comes to a standstill 1 with continued wheel movement VI continues over the predetermined period of time in step S3 determines that the critical condition is present. The predetermined period of time is shown in step S3 takes into account only very brief situations in which the wheels 3rd spin while the loader is turning 1 not moved, disregarded. However, the period is variable and can also be set to zero if necessary.

The method of the present embodiment may detect the presence of a pile entrance of the wheel loader 1 Detect very quickly with simple means and then determine whether the vehicle is essentially stationary while one or more wheels are moving 3rd of the wheel loader 1 keep turning due to slippage. After detection of the critical condition in the step S3 can thus immediately take appropriate countermeasures VII be taken to counteract this critical condition. This is done in step S4 in the present embodiment, the drive torque value T the drive device 2 degraded. Because of this reduction in the drive torque value T can the wheels 3rd be transferred from the slip state back into the engaged state. The drive torque value is used for this purpose T in the present embodiment is gradually decreased at a predetermined rate of decrease until in step S2 it is determined that the wheel loader is at a standstill 1 no longer exists with wheel movement. Then the drive torque value becomes T held at this reduced value for a predetermined period of time and then gradually increased starting from the reduced value at a predetermined rate of increase by, if necessary, a movement of the wheel loader 1 due to the intervention of the wheels that is now present again 3rd to enable.

Incidentally, in the present embodiment, after the critical condition has been eliminated due to the execution of the step S4 the procedure at step S1 performed again to a subsequent entry of the wheel loader 1 to be recorded in a cargo heap.

In the embodiment of the method described above, the in 2 The detected or determined values shown are compared with values stored in advance, so that the shovel can enter 5 of the wheel loader 1 can be recognized in the cargo heap. In a modified embodiment, a map can be stored in the storage device of the control device 4th be provided that contains the expected curves of the corresponding variables. The recorded curves of the variables are then compared with the expected curves of the variables from the characteristics map in order to determine whether the wheel loader is entering 1 is present in the cargo heap. The courses provided in the characteristic map are determined empirically. The courses are then given appropriate bandwidths in order to take into account deviations in the actual courses.

In the embodiment described above, the magnitude of the acceleration measurement value is a with the acceleration limit a (max) compared. This has the advantage that the wheel loader moves cyclically 1 can easily be taken into account in forward and backward movement. In a modified embodiment, the acceleration value is a directly with the acceleration limit value a (max) compared. In this case it must be taken into account that the acceleration value a can assume positive and negative values and then the acceleration limit value a (max) must also be specified for the positive and negative areas. In a modified embodiment, a mean value of the measured acceleration value is used a or its amount calculated in a predetermined period of time that corresponds to the acceleration limit value a (max) is compared.

In a modified embodiment, in step S1 in addition, the recorded drive torque value T be evaluated. On the basis of this evaluation of the recorded drive torque value T can be the presence of the pile entrance by the wheel loader 1 be validated. The characteristic expected course of the drive torque value is used here T used, which is stored in a map.

List of reference symbols

1

Wheel loader

2

Drive device

3

drive wheel

4th

Control device

5

shovel

6th

Mast

7th

Accelerometer

8th

Mast position sensor

9

Bucket orientation sensor

10

Input speed sensor

S1

Heap entry detection step

S2

Standstill determination step

S3

State determination step

S4

Operation control step

a

Acceleration reading

a (max)

Acceleration limit

rpm

Speed value

rpm (max)

Speed limit

HP

Mast position value

SP

Blade position value

there

Acceleration gradient

there (max)

Acceleration gradient limit

drpm

Speed gradient

drpm (max)

Speed gradient limit

T

Drive torque value

dT

Drive torque gradient

I.

Driveway in heaps

II

Discharge drive

III

Wheel is spinning

IV

Detection of pile entrance

V.

Evaluation of the load on the drive device

VI

Wheel movement despite standstill of the construction machine

VII

Initiate countermeasures

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• US 9555706 B1 [0004]

Claims (12)

Method for controlling a construction machine (1), the construction machine (1) having a shovel (5) mounted on a lifting frame (6) for picking up cargo, wheels (3) for moving the construction machine (1) and a drive device (2) is provided for driving the wheels (3), the method comprising the following steps: a heap entry detection step (S1) for detecting an entry of the shovel (5) of the construction machine (1) into a load heap at least on the basis of an acceleration gradient (da) which represents a gradient of an acceleration in the direction of travel of the construction machine (1), and a speed gradient ( drpm), which reproduces a gradient of a speed of an element of the drive device (2); a standstill determination step (S2) for detecting a standstill of the construction machine (1) with continued wheel movement, the speed of the construction machine (1) in the direction of movement falling below a predetermined limit value and the wheels (3) of the construction machine (1) continuing to turn, on the basis a detected acceleration value (a) which represents an acceleration of the construction machine (1) in the direction of movement, and a speed value (rpm) which represents a speed of an element of the drive device (2); and a state determination step (S3) for determining a critical operating state of the construction machine (1), the critical operating state of the construction machine (1) being determined if the standstill of the construction machine (1) determined in the standstill determination step (S2) with continued wheel movement exceeds a predetermined one Duration continues after the entry of the bucket (5) of the construction machine (1) into the load pile has been recognized in the pile entry recognition step (S1). Procedure according to Claim 1 , characterized in that a drive torque gradient (dT) of the drive device (2) is additionally taken into account in the pile entry recognition step (S1). Method according to one of the preceding claims, characterized in that the heap entry detection step (S1) is carried out in a detection phase in that values of temporal gradients, which are taken into account in the heap entry detection step (S1), with predetermined values of temporal gradients which occur when the construction machine ( 1) expected to be compared. Method according to one of the preceding claims, characterized in that in the pile entry recognition step (S1) it is recognized that the bucket (5) of the construction machine (1) has entered a load pile if the acceleration gradient is due to the deceleration of the construction machine (1) (da) is less than a predetermined acceleration gradient limit value (da (max)) and the speed gradient (drpm) is less than a predetermined speed gradient limit value (drpm (max)). Method according to one of the preceding claims, characterized in that in the heap entry detection step (S1) a shovel position value (SP), which indicates an orientation of the shovel (5) in relation to the construction machine (1), is additionally recorded. Method according to one of the preceding claims, characterized in that in the standstill determination step (S2) it is determined whether a relation between the detected acceleration value (a), which represents an acceleration of the construction machine (1) in the direction of movement, and the speed value (rpm), which represents a speed of an element of the drive device (2) is plausible, it being determined that a standstill is present with continued wheel movement if it is determined that the relation is not plausible over a predetermined period of time. Method according to one of the preceding claims, characterized in that it is determined in the standstill determination step (S2) that a standstill is present with continued wheel movement if the detected acceleration value (a) is less than a predetermined acceleration limit value (a (max)), while the detected The speed value (rpm) is greater than a speed limit value (rpm (max)). Method according to one of the preceding claims, characterized in that when the critical state of the construction machine (1) is determined in the state determination step (S3), an operating control step (S4) is carried out in which the drive device (2) of the construction machine (1) is controlled in this way that the critical condition is counteracted. Method according to one of the preceding claims, characterized in that when the critical state of the construction machine (1) is determined in the state determination step (S3), an operating control step (S4) is carried out in which an output torque of the drive device (2) of the construction machine (1) is reduced becomes. Procedure according to Claim 9 , characterized in that the output torque of the drive device (2) of the construction machine (1) is kept at the reduced value for a predetermined period of time and is increased after a predetermined condition has been met. Control device (4) for a construction machine (1) with an input interface at least for receiving signals from an acceleration sensor (7) for detecting an acceleration (a) of the construction machine (1) and a drive speed sensor (10) for detecting a speed (rpm) of an element a drive device (2) of the construction machine (1), as well as with an output interface for outputting signals for an intervention in the operation of the drive device (2) of the construction machine (1), wherein the control device (4) is set up to implement the method according to a of the Claims 1 - 10 to execute. Construction machine (1) with a lifting frame (6), a shovel (5) mounted on a lifting frame (6) for picking up cargo, wheels (3) for moving the construction machine (1) and a drive device (2) for driving the wheels ( 3), furthermore with a control device (4) according to Claim 11 .

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