DE102020125036B3 - working machine - Google Patents

Abstract

A working machine (1) is described with a working device (2) or a mount (10) for a working device, precisely one main vehicle axle (3), with wheels (4) arranged on both sides of the main vehicle axle (3). Drive units (9) are assigned to the wheels (4). Furthermore, the work machine (1) comprises at least one auxiliary wheel (6), the auxiliary wheel (6) comprising at least one device for load detection. The work machine (1) also includes a displaceable weight (5), a position of the displaceable weight being able to be regulated via a controller such that the load on the auxiliary wheel (6) lies within a lower and upper limit value. Furthermore, the working machine (1) comprises at least one controller, the controller comprising at least one control loop which, when the value falls below the lower limit value, controls the drive units in such a way that the applied drive torque is changed in such a way that the vehicle is prevented from tipping over.

Description

technical field

The invention relates to a work machine according to the preamble of claim 1.

State of the art

Working machines are known from the prior art in which the center of gravity of the vehicle can be shifted using a shiftable weight.

So will on the EP 0 383 279 A2 pointed out, which also discloses a working machine that achieves a shift in the center of gravity with at least partial shifting of a drive unit.

Next will be on the U.S. 5,685,563 A and the WO 89/06117 A1 referenced, both of which disclose a work machine in which tipping over by adjusting components is to be prevented.

In the DE 10 2017 100 963 B4 describes a working machine that can change its center of gravity with a weight that can be displaced along a longitudinal axis of the vehicle. Work machines that have an implement at the front end, such as wheel loaders, can be built lighter and operate more agilely through the use of a sliding weight than comparable vehicles with a counterweight fixedly mounted at the rear end. The larger the displacement range, the better the load-empty weight ratio and thus the energy efficiency of the machines. The load distribution on vehicles with two or more axles can be adjusted between these axles by means of the displaceable weight. the DE 10 2017 100 963 B4 also describes a vehicle with a displaceable weight, which comprises only one main vehicle axle. Such a work machine with only one main vehicle axle can use its work implement to perform the same tasks as machines with two or more axles can do. The aim of these work machines is to accomplish these tasks in the same amount of time, but with the work machines being built comparatively smaller and lighter. In addition, they can perform the steering function using different speeds or directions of rotation of the two wheels in such a way that they are significantly more manoeuvrable than machines with four or more wheels. These work machines can balance themselves around the main vehicle axis. An auxiliary wheel is used for driving situations that involve dynamic changes in the forces on the implement, or that require rapid braking maneuvers and which therefore place excessive demands on the control circuit for self-balancing. The load on the auxiliary wheel is controlled by a second control loop. However, the auxiliary wheel should not be heavily loaded, otherwise the wheels of the main vehicle axle have less load and therefore have less traction.

Since the vehicle is only steered via the different speeds and directions of rotation of the wheels on the main vehicle axle and the auxiliary wheel is also steered passively, the steerability and thus the agility of the vehicle is restricted by the fact that the auxiliary wheel is heavily loaded.

The disadvantage here, however, is that when the load on the auxiliary wheel is low, the vehicle can tip over forwards if the vehicle's center of gravity is quickly shifted by dynamic forces in the direction that places even less stress on the auxiliary wheel and lifts the auxiliary wheel off the ground leads. The vehicle then loses stability and threatens to tip over. For this reason, in the work machines from the prior art, the lower limit value to which the load on the auxiliary wheel is regulated by the position control of the displaceable weight cannot fall below a specific minimum value, which limits the agility of the vehicle.

object of the invention

The object of the present invention is to overcome the disadvantages of the prior art. In particular, the object of the invention is to provide a working machine or a vehicle that is suitable for processing the work tasks that are common today for working machines and has a high degree of maneuverability and flexibility. Furthermore, it is the object of the invention to provide a work machine or a vehicle which has a lower weight with the same level of performance as well as greater agility and a lower density of parts. Furthermore, it is the object of the invention to provide a working machine or a vehicle which should be usable as a base carrier vehicle for various working devices. In addition, the object of the invention is to provide a work machine or a vehicle that is intended to enable an increase in productivity and that also meets modern ecological requirements.

solution of the task

The features according to claim 1 lead to the solution of the problem.

Advantageous configurations are described in the dependent claims. A working machine according to the invention comprises a working device or a receptacle for a working device. Furthermore, the work machine according to the invention comprises precisely one main vehicle axle, with wheels being arranged on both sides of the main vehicle axle. A separate drive unit is assigned to each of the wheels arranged on both sides of the main vehicle axle. Furthermore, the working machine according to the invention comprises at least one auxiliary wheel, the auxiliary wheel comprising at least one device for load detection.

Furthermore, the work machine according to the invention comprises a displaceable weight, with the position of the displaceable weight being able to be regulated via a controller in such a way that the load on the auxiliary wheel lies within a lower and upper limit value. Furthermore, the working machine according to the invention comprises at least one controller, the controller comprising at least one control loop which, when the value falls below the lower limit value, controls the drive units in such a way that the applied drive torque is changed in such a way that the vehicle is prevented from tipping over. For this purpose, vehicles with a movable weight and a movable working device are to be used.

A preferred exemplary embodiment of the working machine according to the invention thus has two driving modes. In the self-balancing driving mode, the auxiliary wheel is not on the ground. The vehicle balances around the main vehicle axis with the help of inclination sensors and is controlled via the amount of torque and speed of the wheels on the main vehicle axis and via the position shift of the movable weight. In the auxiliary wheel driving mode, on the other hand, the auxiliary wheel is on the ground and takes on a load that is determined by load sensors and that can be regulated by shifting the position of the movable weight within an upper and lower limit value.

The work machine according to the invention thus has the option of always placing the main load on the main vehicle axle and keeping the load on the auxiliary wheel within a range that can be predetermined by the limit values. Due to the low load on the auxiliary wheel, the maneuverability of the work machine in this driving mode remains just as good as in the self-balancing driving mode. However, the demands on the control and the controllability are higher, especially in difficult terrain when self-balancing. In this case, the control speed that the vehicle has available for driving on two wheels may be too slow. The rapidly changing forces that the implement can have on the working machine, or forces that can suddenly act on the wheels due to a very uneven road surface, are easier to control if the auxiliary wheel takes on a portion of the load, even if this portion is significant is less than that of the wheels of the main vehicle axle.

Furthermore, the vehicle requires more energy for the drive units when balancing in difficult terrain or when standing on two wheels. Optimum use of energy is an essential requirement for a modern ecological working machine. The self-balancing driving mode is therefore suitable for driving on level roads and at higher driving speeds. The advantage is that in the self-balancing driving mode, the vehicle does not experience any pitching accelerations or pitching movements due to bumps in the road. The additional energy consumption of the drive units, which is required for balancing, is low at higher driving speeds. The auxiliary wheel driving mode, on the other hand, is suitable for driving on uneven roads, with rapidly changing forces that can be exerted on the working machine by the implement, for example, when driving slowly and when standing still.

In order to keep the load on the auxiliary wheel small and thus keep the maneuverability and agility of the work machine similar to driving in the self-balancing driving mode, a control circuit in the control system of the work machine according to the invention detects the load on the auxiliary wheel. This can be done by load sensors that are arranged on the auxiliary wheel or on a mount for the auxiliary wheel. This load changes with the shifting of the shiftable weight. By moving the shiftable weight further away from the main vehicle axis, the load on the auxiliary wheel increases. If, on the other hand, it is brought closer to the main vehicle axis, this load decreases. Thus, the control circuit is able to change the load on the auxiliary wheel so that it is within a range that is characterized by a lower and an upper limit.

However, the speed of this control circuit is mainly limited by the fact that the shiftable weight needs time for the shift. For this, frictional forces have to be overcome, as well as the inertial force of the weight, which counteracts the displacement force. drives the For example, the working machine is on an uneven road and sudden forces act on the wheels of the main vehicle axle, then the load on the auxiliary wheel can also decrease suddenly. If this load reaches the value zero, the vehicle is in danger of tipping over before this load can be increased by shifting the shiftable weight. This can be counteracted by setting the lower limit for the load high. The height of the lower limit value thus also represents security against the vehicle tipping over.

In the work machine according to the invention, in contrast to the work machines from the prior art, the lower limit value can be chosen to be very low, since the drive units of the wheels of the main vehicle axle are used to help prevent the vehicle from tipping over if the lower limit value is quickly undershot. Because drive units are selected for this that can change their torque very quickly, as is the case with electric motors, for example, an additional, fast-acting control loop can be created. Similar to the control loop that uses the displacement of the shiftable weight to adjust the load on the auxiliary wheel, the second control loop uses the variation in torque of the drive units to either prevent tipping when the auxiliary wheel is already in the air or the load on the auxiliary wheel suddenly moves downwards so quickly that the movement of the movable weight, which is too slow for this, cannot prevent the load from falling below the lower limit value.

With the second control circuit, the low control speed of the first control circuit can thus be compensated and a vehicle can be created which can be operated in driving mode auxiliary wheel and is therefore still very agile and manoeuvrable on uneven roads. If, for example, the work machine according to the invention drives forwards on an uneven roadway, i.e. in the direction of the side of the vehicle opposite the auxiliary wheel, and if a substantially constant drive torque is applied to the drive units of the wheels of the main vehicle axle, then the displaceable weight is in a constant position, which is so adjusted so that the load on the auxiliary wheel is slightly above the lower limit. If this working machine drives through a pothole or a trough in the road, for example, the load on the auxiliary wheel drops abruptly. The load reduction is recorded by the load sensors on the auxiliary wheel and reported to the controller. The sliding weight is immediately accelerated and moves backwards.

Specifications such as front, rear, top and bottom are based on the correctly used work machine, which stands on the ground below and, for example, lifts the work implement off the ground and drives forwards and drives backwards backwards.

However, the auxiliary wheel can still lift off the ground. The second control circuit then superimposes an additional drive torque on the drive torques of the drive units that are already present, the level of which depends on the preceding driving resistances. Due to the higher drive torque, the working machine is accelerated forward. This creates a reaction torque on the drive units, which acts on the working machine in the direction in which the working machine would like to tip backwards, or in which the auxiliary wheel is pressed down. Thus, the working machine can be prevented from tipping over forward.

In addition to the load sensors for the load on the auxiliary wheel, the inclination sensors provided for the self-balancing control circuit can also be used for this second control loop. These recognize the tilting movement of the vehicle when the auxiliary wheel has already lifted off the ground. You can also see whether the vehicle is righting itself again as a result of the higher drive torque, or whether the superimposed torque has to be increased even further. Inclination sensors, together with the drive units, are therefore part of the control loop in the auxiliary wheel driving mode.

If the vehicle according to the invention drives backwards, i.e. in the direction of the auxiliary wheel, and there is a torque in this direction, which depends on the driving resistance, then this drive torque must also be changed when driving through a pothole in order to avoid tipping over. In this case, however, the existing drive torque is reduced in order to obtain the same effect as when driving forward.

In a preferred exemplary embodiment of the work machine according to the invention, this superimposed torque, which prevents the vehicle from tipping over, is only applied until the load on the auxiliary wheel is again above the lower limit value. Since the displaceable weight also shifts backwards at the same time when it is detected that this limit value has not been reached, the duration of the superimposed torque can be kept short. Thus, excessive acceleration of the vehicle speed is avoided. It is also possible to determine the point in time at which the superimposed torque is reversed again the position sensors can be used, which can indicate that the vehicle has righted itself so far that the auxiliary wheel is on the ground again. So if the auxiliary wheel lifts off the ground or up, it is guided back to the ground by the superimposed torque. The vehicle therefore only drives on two wheels for a short time and is immediately returned to the auxiliary wheel driving mode, in which the auxiliary wheel rests on the ground with a low load. The constantly recurring return of the auxiliary wheel to the ground is carried out as long as the controller has a signal which is to keep the vehicle in the auxiliary wheel mode with a low load, which has therefore selected the auxiliary wheel driving mode.

If the corresponding signal is different, namely that a change to the self-balancing driving mode is to take place, the load on the auxiliary wheel is reduced by shifting the displaceable weight until it has reached zero. At the same time, the control circuit that is required for self-balancing using the inclination sensors is switched on.

In a further preferred exemplary embodiment of the work machine according to the invention, the lower and upper limit values can be changed. These can be selected differently, for example, depending on the road surface or the application. The limit values can be defined either by an operator, who does this either via a control element on the vehicle or via a remote control. Or the limit values can also be changed by automatic functions that are designed to optimize the respective driving situation.

In a further preferred exemplary embodiment, the driving speed is used for the automatic optimization of the limit values. In a further embodiment, the auxiliary wheel is arranged on the displaceable weight. This has the advantage that the load on the auxiliary wheel does not increase significantly when the movable weight is extended far to the rear. However, it can also be arranged on the rear part of the vehicle frame.

character list

• 1 eine schematische Darstellung eines Ausführungsbeispiels einer erfindungsgemäßen Arbeitsmaschine.

Further advantages, features and details of the invention result from the following description of preferred exemplary embodiments and from the drawings; these show in:

• 1 a schematic representation of an embodiment of a working machine according to the invention.

example

In 1 a preferred working machine 1 according to the invention is shown, which eliminates or at least minimizes the disadvantages of working machines from the prior art. The working machine 1 according to the invention comprises a working device 2 which is connected to the vehicle via the mount 10 . The implement 2 can be raised for transport via the receptacle 10 . The working device 2 shown is a shovel 11 as used in wheel loaders. However, all implements that are used in construction and/or in agriculture and that require a carrier vehicle are conceivable as implements that are arranged on the receptacle 10 . In addition, the working machine 1 comprises at least one main vehicle axle 3 with wheels 4 arranged on both sides.

Furthermore, the work machine 1 according to the invention comprises a displaceable weight 5 which is connected to the vehicle frame 13 via a linkage 12 . The linkage 12 is arranged in such a way that the displaceable weight 5 can be displaced over a wide range, so that it can be brought very close to the main vehicle axis 3 and that the vehicle is therefore very compact. Due to the wide range of displacement, the displaceable weight 5 can be comparatively small and still compensate for the weight of a heavy implement 2 via the leverage effect when it is lifted, without the vehicle losing its stable position.

In a preferred exemplary embodiment of the work machine 1 according to the invention, the displaceable weight 5 comprises elements such as, for example, energy converters, electric batteries or hydraulic systems for supplying the hydraulic cylinders.

Furthermore, the working machine according to the invention has 1 swivel arms 7 and working arms 8 with which the working device 2 can be moved. An auxiliary wheel 6 is arranged on the displaceable weight 5 and is rotatably mounted in such a way that it can make passive steering movements. The steering movements of the work machine 1 according to the invention are effected by the different speeds or directions of rotation of the drive units 9 which drive the wheels 4 which are arranged at the two outer ends of the main vehicle axle 3 . The work machine 1 can therefore be operated in a very manoeuvrable and agile manner. The auxiliary wheel 6 can either be in the air. Then the working machine 1 balances around the main vehicle axle 3. Or the auxiliary wheel 6 is in contact with the ground, taking up a significantly lower load than the wheels 4 of the main vehicle axle 3. The steering movements, which are specified by the drive units 9, then automatically lead to a rotation of the auxiliary wheel 6, with which this is also steered passively.

Furthermore, the support for the auxiliary wheel 6 on the displaceable weight 5 includes at least one load sensor that can measure the load, ie the force that acts between the ground and the auxiliary wheel. In a further exemplary embodiment, this force can also be measured at any point on the linkage 12, in which case the weight of the displaceable weight can then be taken into account.

In a further exemplary embodiment, the accommodation of the auxiliary wheel 6 can comprise a device with which the auxiliary wheel can be moved upwards in relation to the displaceable weight 5 or in relation to the vehicle frame 13 . This increases the distance between the roadway and the auxiliary wheel 6 when balancing about the main vehicle axis 3.

The work machine 1 according to the invention can be operated using at least two driving modes. In the self-balancing driving mode, the auxiliary wheel 6 is load-free and/or is in the air. It therefore has no contact with the road. The control of the work machine 1 includes a control loop that includes inclination sensors, which controls the drive units and the movable weight. Another driving mode, the driving mode auxiliary wheel, consists in that the control comprises a control circuit which includes inclination sensors and also load sensors on the auxiliary wheel and which controls the displaceable weight and the drive units. This control loop controls the position of the displaceable weight 5 in such a way that the load on the auxiliary wheel 6 is set above a lower limit value and below an upper limit value.

These limit values are set in such a way that the upper limit causes a significantly lower load on the auxiliary wheel than on the wheels 4 of the main vehicle axle 3. Since only these wheels have drive units, the largest proportion of the vehicle weight can be used to generate traction . In contrast to prior art work machines that include four or more driven wheels, the work machine 1 according to the invention is able to provide the same traction with only two driven wheel elements. In addition, the low load ensured by the upper limit makes the work machine 1 easy to steer. The lower limit is set so that the work machine 1 cannot tip over forward when running on a rough terrain or a rough road. It is taken into account here that the displacement of the displaceable weight 5 has a reaction time that is predetermined by the speed of the control loop and the acceleration and movement speed of the displaceable weight 5 . If the lower limit value is high, then the working machine 1 does not yet tip over when the value falls below the lower limit value. This means that more time is available for the control loop. In the working machine 1 according to the invention, however, the lower limit value is chosen to be low. In a preferred embodiment, this is essentially close to zero. The control loop controls the drive units with a significantly shorter reaction time in such a way that the working machine 1 is prevented from tipping over. This takes place, for example, when driving forwards by increasing the drive torque of the drive units 9. Since, in a preferred exemplary embodiment of the work machine according to the invention, electric motors are used as the drive units 9, which have very short reaction times for increasing their torque, the overall reaction time of this control circuit is also very short short. Due to the higher torque, the working machine can be erected quickly if it tips over, until the auxiliary wheel 6 is back on the ground. This control circuit uses not only the signals from the load sensors on the auxiliary wheel 6, but also the inclination sensors, which also deliver usable signals when the auxiliary wheel is already in the air. The aim of the control circuit in this auxiliary wheel driving mode is not driving on two wheels, but on at least three. If the auxiliary wheel lifts off the ground, the level of the superimposed torque on the drive units 9 is selected so high that the auxiliary wheel is returned to the ground again. Likewise, the time during which the drive units 9 have an increased torque is limited to such an extent that the auxiliary wheel 6 is loaded again as quickly as possible, but without hitting the ground too hard.

The lower and upper limit values can be set either manually by an operator using an operating element or by remote control. However, this determination can also be made by an automatic function of the controller. For example, the driving speed can be used for this. The selection of one of the two modes can also be controlled either manually by an operator, for example by a control element or radio remote control, or by an automatic function of the controller. This can, for example, take into account the driving speed, with the self-balancing driving mode being selected at higher driving speeds and the auxiliary wheel driving mode being selected at slower driving speeds. For this festival other sizes can also be taken into account. For example, GPS data can identify the location of the work machine. If this was previously operated at the same location and the unevenness of the ground was very large at this point, the limit values and switching to the auxiliary wheel driving mode can be specified. Sensors suitable for this purpose can also be used to detect the unevenness, such as the inclination sensors or acceleration sensors.

Although only a few preferred embodiments of the invention have been described and illustrated, it is obvious that those skilled in the art can add numerous modifications without departing from the spirit and scope of the invention.

reference list

1

working machine

2

implement

3

main vehicle axis

4

wheel

5

Movable weight

6

auxiliary wheel

7

swivel arm

8th

working poor

9

drive unit

10

admission

11

shovel

12

linkage

13

vehicle frame

Claims (12)

Working machine (1) comprising: - a working device (2) or a receptacle (10) for a working device (2), - precisely only one main vehicle axle (3), - wheels (4) arranged on both sides of only one main vehicle axle (3), - drive units (9) assigned to the wheels (4), - at least one auxiliary wheel (6), the auxiliary wheel (6) comprising at least one device for detecting the load, characterized by a displaceable weight (5), a position of the displaceable weight (5 ) is regulated via a controller in such a way that the load on the auxiliary wheel (6) lies within a lower and upper limit value, with at least one controller being present and the controller comprising a control loop which, when the lower limit value is fallen below, activates the drive units in such a way that that the driving torque applied can be changed in such a way that it is suitable for preventing the vehicle from tipping over. Working machine (1) after claim 1 , characterized in that the controller activates the drive units (9) when the auxiliary wheel (6) lifts off the ground in such a way that the torque of the drive units (9) can be changed in a way that is suitable for preventing the working machine from tipping over and that the auxiliary wheel (6 ) can be traced back to the ground. Working machine (1) after claim 1 or 2 , characterized in that the controller activates the drive units (9) when the value falls below the lower limit value in such a way that the torque of the drive units (9) can be changed in a way that is suitable for preventing the vehicle from tipping over, with the change in torque required for this only being applied for as long until the load on the auxiliary wheel (6) is above the lower limit again. Working machine (1) according to one of Claims 1 until 3 , characterized in that the controller activates the drive units (9) when the lower limit value is not reached in such a way as to prevent the vehicle from tipping over and the position of the displaceable weight (5) is changed until the load on the auxiliary wheel (6) returns is at least the lower limit. Working machine (1) according to one of the preceding claims, characterized in that the controller activates the drive units (9) when the lower limit value is not reached in such a way that the vehicle switches to a driving mode of self-balancing if the control unit receives a signal that contains an instruction after switching to self-balancing driving mode. Working machine (1) according to one of the preceding claims, characterized in that the control circuit is an electronic control circuit and comprises at least inclination sensors and/or load sensors. Working machine (1) according to claim one of the preceding claims, characterized in that there are inclination sensors. Working machine (1) according to one of the preceding claims, characterized in that the drive units (9) are electric drives. Work machine (1) according to one of the preceding claims, characterized in that the lower and upper limit values can be changed. Working machine (1) after claim 9 , characterized in that the upper and lower limit values are changed automatically as a function of the driving speed. Working machine (1) according to one of the above Claims 5 until 10 , characterized in that the machine (1) above a speed automatically switches to the self-balancing driving mode, in which the machine (1) balances around the main vehicle axis and no load is applied to the auxiliary wheel (6). Working machine (1) according to one of the preceding claims, characterized in that the auxiliary wheel (6) is arranged on the displaceable weight (5).

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