WO2010145733A1

WO2010145733A1 - Mobile working machine comprising a device for damping vibrations of a working arm, and method for damping the vibrations

Info

Publication number: WO2010145733A1
Application number: PCT/EP2010/002774
Authority: WO
Inventors: Joachim Rustler
Original assignee: Robert Bosch Gmbh
Priority date: 2009-06-20
Filing date: 2010-05-06
Publication date: 2010-12-23
Also published as: DE102009025683A1

Abstract

The invention relates to a mobile working machine (1) comprising a device (2) for damping vibrations of a working arm (3), wherein a first end (4) of the working arm (3) of the working machine (1) is connected in an articulated manner to a revolving superstructure (5). At least one hydraulic cylinder (6) is disposed between the revolving superstructure (5) and the working arm (3) and defines an angle of inclination (a) between the revolving superstructure (5) and the working arm (3). At least one load sensor (7) is connected to the hydraulic cylinder (6) by means of a pressure line (8). The load sensor (7) senses changes in pressure due to pitch vibrations of the working arm (3). To this end, a signal line (9) is disposed between the load sensor (7) and a control device (10), said signal line (9) transmitting pressure signals to the control device (10). A hydraulic valve (11) is disposed in a supply line and a discharge line (12, 13) of the hydraulic cylinder (6), wherein the hydraulic valve (11) and the hydraulic pump (14) are connected to the control device (10) by means of control lines (15, 16). The hydraulic pump (14) and the hydraulic valve (11) use a regulator (20) in the control device (10) to control the hydraulic flow when pitch vibrations occur so as to counteract changes in pressure and dampen the pitch vibrations.

Description

Mobile work machine with damping device of vibrations of a working arm and method for damping the vibrations

description

The invention relates to a mobile machine with damping device of vibrations of a working arm, wherein the working arm of the working machine is articulated with a first end to a superstructure. At least one hydraulic cylinder is arranged between the uppercarriage and the working arm and defines a tilt angle between the uppercarriage and the working arm.

From the document DE 10 2005 025 536 A1 a mobile working machine, in particular a hydraulically driven earth-moving machine and a method for earth and bulk material movement is known. For this purpose, the mobile work machine is equipped with a complete or at least proportionate automation of the work cycles in earth and bulk material movements, taking into account the vibrations and / or contact forces occurring. This automation is based on a trajectory follow-up control with an active anti-vibration damping and / or a subordinate contact force control, wherein a maximum contact force is defined for the contact force control and, if this threshold value is exceeded, the relevant work cycle is interrupted.

In such automated or semi-automated mobile working machines, unforeseen oscillations of the working arm, which can not be regulated by the automatic mechanism, occur during lowering and lifting under load, which are also known as pitching forces. Called vibrations. These pitching vibrations are particularly dangerous because they can swing open during automatic operation and can stimulate natural vibrations of the entire system of the mobile working machine, so that an automatic operation is no longer guaranteed.

Such pitch oscillations were noticeable and measurable in particular during the testing of a highly dynamic EFM excavator (electronic flow matching) when the working arm or boom was actuated. By simple, known from the prior art control measures, however, no significant improvement or damping of such pitch oscillations could be achieved. The danger of pitching vibrations is not limited to excavators, but can occur in a variety of hydraulic construction machinery, agricultural and forestry machinery and truck loading cranes.

The object of the invention is to provide a mobile machine with damping device of vibrations of a working arm and a method for damping vibrations, so that an improvement in controllability, safety at work, the energy efficiency and the comfort of such mobile work machines is achieved by a reduced vibration excitation.

This object is achieved with the subject matter of the independent claims. Advantageous developments of the invention will become apparent from the dependent claims.

According to the invention a mobile machine with damping device of vibrations of a working arm and a method for damping the vibrations is provided, wherein the working of the working machine is arranged with a first end articulated to a superstructure. At least one hydraulic cylinder is arranged between the uppercarriage and the working arm and defines a tilt angle between the uppercarriage and the working arm. At least one load detection sensor is connected to the hydraulic cylinder via a pressure line connected. The load detection sensor detects pressure changes due to pitch oscillations of the working arm.

For this purpose, a signal line is arranged between the load detection sensor and a control device, which transmits pressure signals to the control unit. A hydraulic valve is arranged in an inlet and a discharge of the hydraulic cylinder, wherein the hydraulic valve and the hydraulic pump are connected to the control unit via control lines. The hydraulic pump and the hydraulic valve regulate by means of a controller in the control unit at the occurrence of pitching oscillations for damping the same Hydraulikzu- or outflow against the occurrence of pressure fluctuations.

An advantage of such a work machine is that vibration excitations by the work arm and the equipment when operating the work arm, for example by acceleration and deceleration of the equipment, are avoided. The load of the consumer is e.g. detected by the load detection sensor and with the help of an electronic control setpoint values for the hydraulic valve and the hydraulic pump are changed so that the acceleration forces counteract the pressure changes and thus the vibration excitation for pitching oscillations with actuated working arm.

In this case, a combination with a passive or an active vibration damping for the non-actuated state of the working arm, e.g. when driving, increase the safety of the mobile work machine. Finally, it is possible to achieve a further improvement of the mobile working machine by detecting the hydraulic cylinders or the alignment positions of the same and / or by a combination with a position control.

The invention can be used particularly effectively for the system with an EFM regulation (electronic flow matching) for mobile machines, which is characterized by the high possible dynamics while avoiding pitch oscillations. is wrong. Another advantage is that with existing electrohydraulic only an additional load detection sensor must be fitted, which can be used eg for a weighing device, so that only the control unit must be supplemented by a control unit in the software equipment. No additional position sensors are required for damping the pitch oscillations, so that a cost-effective implementation for mobile machines while avoiding additional maintenance is possible.

In a preferred embodiment of the invention, the load detection sensor has a sensor element, which communicates with the hydraulic cylinder via a hydraulic line and forwards the pressure signals in the hydraulic cylinder via a signal line to a control unit as electrical signals.

In addition, in a preferred embodiment of the invention, the work machine having a manual control, which sets a target value for a change in the stroke of the hydraulic cylinder, and the inclination speed of the working arm, and thus a lowering or raising the working arm triggers.

Such manual control transmitters are particularly advantageous if a mobile work machine is to operate only semi-automatically and is not provided, as in the publication DE 10 2005 025 536 A1, for fully automatic operation for earthmoving and grading or excavation tasks.

In addition, it is provided that pressure control signals are superimposed on the nominal value of the manual control transmitter in the control unit, wherein the pressure control signals generate setpoints for the hydraulic valve position and setpoints for the hydraulic flow of the hydraulic pump and the hydraulic valve, and the setpoints counteract the measured pressure fluctuations due to pitch oscillations. These setpoints of both the manual control transmitter and the hydraulic pump and the hydraulic valve relate to hydraulic flows and are specified in quantity per unit of time. The controller includes, in addition to the above-mentioned pitch damping damper, a low-pass filter that filters out slow pressure changes due to the lifting and lowering of the working arm from the pressure fluctuations transmitted to the controller by the load detection sensor. For this purpose, the control unit or the controller in the control unit has a subtraction node for subtracting the filtered-out slow pressure fluctuations in the hydraulic cylinder from the total pressure fluctuations while detecting the pitching oscillations of the working arm. In principle, the combination of low-pass filter and subtraction node provides a high-pass filter that transmits only higher-frequency pressure fluctuations due to pitching vibrations and does not take into account the normal hydraulic supply and discharge changes by raising and lowering the working arm for the pressure control signals.

A method for damping vibrations of a working arm has the following method steps. First, hydraulic flow rate setpoints are set in liters per minute for a hydraulic cylinder, which is used to raise and lower a working arm. During operation of the working arm, hydraulic pressure fluctuations in the hydraulic cylinder due to pitching oscillations of the working arm are then detected. Then, the target value of a hydraulic flow of a hydraulic pump and the target value for hydraulic flow are changed by a hydraulic valve for supplying the hydraulic cylinder such that acceleration forces occur on the hydraulic piston of the hydraulic cylinder, which counteract the hydraulic pressure fluctuations. This method has the advantage that the pitching vibrations of the working arm are damped and a uniform lifting and lowering of the working arm is ensured even with high dynamics of the mobile machine.

In this case, the hydraulic pressure fluctuations are preferably determined by a load sensing sensor which has a sensor element which transmits the pressure signals to voltage changes and to a control unit in the control unit supplying a signal line. With the aid of a manual control transmitter, the desired value for the hydraulic flow in the hydraulic cylinder for changing the inclination angle of the working arm is preferably predetermined for the working machine, whereby a lowering or lifting of the working arm is triggered.

This setpoint of the manual control transmitter is superimposed in the control unit pressure control signals of a controller, the setpoint values for the hydraulic valve position and setpoints for the hydraulic flow generated by the hydraulic valve and setpoints for the hydraulic flow of the hydraulic pump. The setpoint values for the manual control transmitter and for the hydraulic pump and for the hydraulic valve are specified in quantity per unit of time (l / min) for a hydraulic flow.

The invention will now be explained in more detail with reference to the accompanying figures.

Figure 1 shows a schematic representation of a mobile machine in the form of a shovel with load;

Figure 2 shows a schematic representation of a working arm of a mobile

Working machine with damping device against pitching vibrations;

FIG. 3 shows a schematic functional diagram of a desired value setting of a control device for a mobile work machine.

Figure 1 shows a schematic representation of a mobile machine 1 in the form of a shovel 25 with a load 22. The load 22 is received by a bucket 23 on a working arm 3 of the excavator 25, wherein the working arm 3 of the working machine 1 with a first end 4 at a superstructure 5 of the excavator 25 is articulated. At least one hydraulic cylinder 6 is arranged between the superstructure 5 and the working arm 3 and defines an angle of inclination a between the superstructure 5 and the working arm 3. Raulikzylinder 6 is connected via a pressure line, not shown here, a load detection sensor. This load detection sensor detects pressure fluctuations due to pitch oscillations of the working arm 3.

These pitching vibrations occur when the working arm 3 is lifted and / or lowered with high dynamics. During the pitching oscillations, the inclination angle α varies by ± Δα, and a second end 24 of the working arm 3 carrying the bucket 23 with the load 22 may vary at a distance a from the ground surface 26 by ± Δa during the pitching oscillations. These pitching vibrations, caused by the rapid lifting or lowering of the bucket 23 with the load 22, cause pressure fluctuations in the hydraulic cylinder 6.

Since the piston rod 27, which is extended in this position by the stroke h between an end 30 of the hydraulic cylinder 6 and a pivot point 28 on the working arm 3, the stroke h would vary by the value ± Δh, unless the hydraulic medium is practically incompressible , Due to the elasticity of the hydraulic medium, the equipment, the vehicle structure and possibly the tire and the ground, pitching oscillations occur, which occur at the second end of the working arm with ± Δa and can be detected as pressure fluctuations in the hydraulic cylinder 6. These pressure fluctuations can be absorbed by the load detection sensor and compensated as far as possible by the damping device according to the invention, as shown in FIG.

FIG. 2 shows a schematic representation of a working arm 3 of a mobile working machine. The working arm 3 is articulated at its first end 4 and moves at its second end 24 a load upwards or downwards, pitch oscillations in directions of arrows A, B may occur, which are shown in dashed lines on a time axis t schematically in Figure 2. Such pitch oscillations, which can occur when lifting and lowering the working arm 3, cause pressure fluctuations in the hydraulic cylinder 6. Variations are fed via a pressure line 8 to a load detection sensor 7 and supplied from the latter via a signal line 9 as voltage fluctuations to a controller 20 in the control unit 10.

The pressure fluctuations in a supply line 12 to the hydraulic cylinder 6 are measured or detected. This hydraulic cylinder 6 is articulated with a first end 29, while protruding from its second end 30, a piston rod 27 which cooperates with a piston 21 in the hydraulic cylinder. This piston rod 27 is connected via a hinge point 28 to the working arm 3. Thus, if a pitching oscillation occurs in the direction of arrow B, as occurs initially on the time axis t during a first half period, the pressure in the supply line 12 to the hydraulic cylinder 6 is increased.

This pressure increase can counteract the vibration damping device 2 in that the hydraulic flow f is increased in liters per minute (l / min) of the hydraulic pump 14 and / or the flow through the hydraulic valve 11 in the supply line 12 to the hydraulic cylinder 6 is increased. Thus, the pitching vibration in the first half-period as shown in the time-dependent diagram is counteracted, so that a damped pitching vibration, as exemplified by the solid line on the time axis t, results.

Another possibility is that the flow through the hydraulic valve 11 for the drain line is increased in this first half period of the pitching oscillation, so that the piston 21 also experiences an acceleration in the direction of the pivot point 28 and thus a damping of the pitching oscillation in the first half period is reached. The changes in the hydraulic flows in the hydraulic supply line 12 and the hydraulic discharge line 13 are signaled by the controller 20 via corresponding control lines 15 to the hydraulic valve or 16 to the hydraulic pump in the form of desired values, which counteract the pressure fluctuations in the hydraulic cylinder. FIG. 3 shows a schematic functional circuit diagram of a setpoint setting of a control device for a mobile work machine for avoiding pitch oscillations of the working arm of the work machine. For this purpose, input variables are available at the inputs a and b, from which at output c the setpoint values for the hydraulic flow through the hydraulic valve and the hydraulic pump are output in liters per minute. At input a is the setpoint for the hydraulic flow, which is specified by a manual control transmitter 17 in l / min.

This set point can act in two directions, once to lower the working arm and once to raise the working arm, depending on the position of the hydraulic valve, which is predetermined by the signal blocks 31 and 32. For lifting the working arm, hydraulic fluid flows into the hydraulic cylinder below the hydraulic piston. To lower the working arm, hydraulic medium flows into the hydraulic cylinder above the hydraulic piston. The setpoint values of these hydraulic flows predetermined by the manual control transmitter are superimposed in the modulation blocks 33 and 34 for compensating pitching oscillations. For this purpose, in the compensation blocks 33 and 34, different setpoint values for the hydraulic flows during lowering or lifting are supplied via different signal paths 35 and 36.

For this purpose, the input b receives the load pressure in the hydraulic cylinder determined by the load detection sensor and branches off from this signal via a low-pass filter 19 the slowly increasing or decreasing hydraulic pressure and feeds it to a subtraction node 18 in which these slow processes are based on the total pressure information of the Load detection sensor are subtracted.

This thus cleaned-up signal, which only has the faster-running pitch movements as pressure fluctuations, is amplified in a multiplier 37 or a PID controller block for the signal path 35. This amplified signal is added in the signal path 35 in an addition block 41 with a reference signal of the reference block 39 and fed via the signal block 43 to the modulation block 33. In the signal path 36, the signal of the operational amplifier 38 is subtracted from a reference signal of the reference signal block 40 in a subtraction block 42 and fed to the signal block 44 for modulating to the setpoint for lifting the working arm.

Thus, at the output c there are varying setpoint values Ci for the hydraulic flow of the hydraulic pump and C ₂ and C ₃ for the hydraulic flow of the hydraulic valve in the two positions for lifting and lowering, the hydraulic flows Ci ₁ C ₂ and C ₃ in l / min Damping of the pitch oscillations are available.

LIST OF REFERENCES

1 work machine

2 damping device

3 working arm

4 first end of the working arm

5 superstructure

6 hydraulic cylinders

7 Load detection sensor

8 pressure line

9 signal line

10 control unit

11 hydraulic valve

12 hydraulic supply line

13 Hydraulic drainage

14 hydraulic pump

15 control line

16 control line

17 hand control transmitter

18 subtraction nodes

19 low-pass filter

20 controllers in the control unit

21 hydraulic pistons

22 load

23 excavator bucket

24 second end of the working arm

25 shovels

26 Earth's surface

27 piston rod

28 Hinge point of the working arm

29 first end of the hydraulic cylinder 30 second end of the hydraulic cylinder

31 signal block

32 signal block

33 Modulation block 34 Modulation block

35 signal path

36 signal path

37 multiplier

38 operational amplifier 39 reference block

40 reference block

41 addition block

42 subtraction block

43 signal block 44 signal block

Claims

claims

1. Mobile machine with damping device (2) of vibrations of a working arm (3), wherein the working arm (3) of the working machine (1) with a first end (4) on an upper carriage (5) is articulated, and wherein at least one hydraulic cylinder (6) between the superstructure (5) and working arm (3) is arranged and an inclination angle (a) defined between the uppercarriage (5) and working arm (3), and wherein at least one load detection sensor (7) with the hydraulic cylinder (6) via a pressure line (8) is connected and pressure changes due to pitching vibrations of the working arm (3) detected, and wherein a signal line (9) between the load detection sensor (7) and a control unit (10) is arranged, which transmits pressure signals to the control unit (10), and wherein a hydraulic valve (11) in a Hydraulikzu- and a hydraulic discharge (12, 13) of the hydraulic cylinder (6) is arranged, wherein the hydraulic valve (11) and a hydraulic pump (14) with the control unit (10) via control lines (15, 16) are connected, and wherein the hydraulic pump (14) and the hydraulic valve (11) at the occurrence of pitching oscillations for damping the same hydraulic inflow or outflow against the occurrence of pressure changes by means of a regulator (20) in the control unit (10).

2. Work machine according to claim 1, characterized in that the load detection sensor (7) has a sensor element that converts hydraulic pressure changes in voltage fluctuations.

3. Work machine according to claim 1 or claim 2, characterized in that the working machine (1) has a manual control transmitter (17) having a desired value for the hydraulic cylinder (6) and the inclination speed of Working arm (3) pretends, as well as a lowering or lifting the working arm (3) triggers.

4. Work machine according to claim 3, characterized in that the target value of the manual control transmitter (17) in the control unit (10) pressure control signals are superimposed, the setpoint values for the hydraulic valve position and setpoints for the hydraulic flow of the hydraulic pump and the hydraulic valve generate, wherein the setpoint values measured Counteract pressure fluctuations due to pitching vibrations.

5. Working machine according to claim 4, characterized in that the setpoints of the manual control transmitter (17) and the hydraulic pump (14) specify hydraulic flows in liters per minute.

6. Work machine according to one of the preceding claims, characterized in that; in that the control unit (10) has a low-pass filter (19) which filters out slow pressure changes from the pressure fluctuations.

7. Work machine according to one of the preceding claims, characterized in that the control unit (10) has a subtraction node (18) for subtracting the filtered out slow pressure fluctuations in the hydraulic cylinder (6) from the total pressure changes while detecting the pitch oscillations of the working arm (3).

8. A method for damping vibrations of a working arm (3), comprising the following method steps: Specification of hydraulic flow setpoints in liters per minute for a hydraulic cylinder (6), which is used to raise and lower a working arm (3); Detecting hydraulic pressure changes in the hydraulic cylinder (6) due to pitch oscillations of the working arm (3);

Changing the setpoint value of a hydraulic flow of a hydraulic pump (14) and the hydraulic flow through a hydraulic valve (11), for supplying the hydraulic cylinder (6) such that acceleration forces on a hydraulic piston (21) of the hydraulic cylinder (6) counteract the hydraulic pressure fluctuations ,

9. The method according to claim 8, characterized in that the hydraulic pressure fluctuations determined by a load detection sensor (7) and transmitted by a sensor element in voltage fluctuations and a control unit (10) via a signal line (9) are supplied.

10. The method according to claim 8 or claim 9, characterized in that the desired value for the hydraulic flow in the hydraulic cylinder (6) for changing the inclination angle (a) of the working arm (3) by a manual control transmitter (17) of the working machine (1) is predetermined , whereby a lowering or lifting of the working arm (3) is triggered.

11. The method according to claim 10, characterized in that the target value of the manual control transmitter (17) in the control unit (10) pressure control signals are superimposed, generate the setpoints for the hydraulic valve position and setpoints for the hydraulic flow of the hydraulic pump (14), wherein the setpoints counteract the measured hydraulic pressure fluctuations due to pitching oscillations.

12. Work machine according to claim 11, characterized in that the setpoint values of the manual control transmitter (17) and for the hydraulic pump

(14) are given in quantity per unit time for a hydraulic flow.