Method for controlling the movement of a boom, and work machine

Abstract

A method controls the movement of a boom, wherein the boom is moved by a plurality of hydraulic drives. Each hydraulic drive is fed with a hydraulic medium, the pressure and/or volume flow of which is adjustable. The method predefines a desired direction of movement and a desired speed of a boom tip; predictively calculates a pressure and/or a volume flow required for each of the hydraulic drives that are required for the desired direction of movement and desired speed; subsequently generates a supply pressure depending on the predictively calculated pressures and/or subsequently generating a supply volume flow as a function of the predictively calculated volume flows; and subsequently feeds the hydraulic drives required for the desired direction of movement and desired speed with the hydraulic medium having a respective feed pressure and/or a respective feed volume flow such that the boom tip moves in the desired direction of movement at the desired speed.

Claims

1. A method for controlling movement of a boom, the boom being moved by way of a plurality of hydraulic drives, a respective hydraulic drive being fed with a hydraulic medium, a pressure of which and/or a volumetric flow of which is settable, the method comprising the steps of: specifying a desired movement direction and a desired speed of a boom tip; predictively calculating a respective required pressure and/or a respective required volumetric flow for one or more hydraulic drives which are required for the desired movement direction and the desired speed based on measured values of sensors which detect an instantaneous load of the boom and based on a boom model; subsequently generating a supply pressure in a manner which is dependent on the predictively calculated pressures and/or subsequently generating a supply volumetric flow in a manner which is dependent on the predictively calculated volumetric flows; and subsequently feeding the one or more hydraulic drives which are required for the desired movement direction and the desired speed with the hydraulic medium at a respective feed pressure and/or a respective feed volumetric flow such that the boom tip moves in the desired movement direction at the desired speed.

2. The method as claimed in claim 1, wherein a supply line is loaded with the supply pressure and/or the supply volumetric flow is conducted in the supply line, and a respective feed pressure is derived from the supply pressure and/or a respective feed volumetric flow is derived from the supply volumetric flow.

3. The method as claimed in claim 1, wherein the generating of the supply pressure comprises the steps of: determining a highest load pressure under the respective predictively calculated pressures, and generating the supply pressure in a manner which is dependent on the determined highest load pressure.

4. The method as claimed in claim 1, wherein at least part of the hydraulic drives are hydraulic cylinders.

5. The method as claimed in claim 1, wherein the supply pressure and/or the supply volumetric flow are generated by a single hydraulic pump.

6. A work machine, comprising: a boom; a plurality of hydraulic drives which are configured to move the boom, a respective hydraulic drive being fed with a hydraulic medium, the pressure of which and/or the volumetric flow of which is settable; a setting device, by which a desired movement direction and a desired speed of a boom tip is specified, a computing unit which is configured to predictively calculate a respective required pressure and/or a respective required volumetric flow for one or more hydraulic drives which are required for the desired movement direction and the desired speed based on measured values of sensors which detect an instantaneous load of the boom and based on a boom model; a pressure generating device and/or a volumetric flow generating device configured, following the predictive calculating, to generate a supply pressure in a manner dependent on the predictively calculated pressures and/or a supply volumetric flow in a manner dependent on the predictively calculated volumetric flows; and a feed device configured to bring about subsequent feeding of the one or more hydraulic drives which are required for the desired movement direction and the desired speed with the hydraulic medium at a respective feed pressure and/or a respective feed volumetric flow such that the boom tip moves in the desired movement direction at the desired speed.

7. The work machine as claimed in claim 6, wherein the work machine is a mobile crane or an aerial work platform.

8. The work machine as claimed in claim 6, wherein the work machine is an auto concrete pump.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following text, the invention will be described in detail with reference to the drawings, in which, diagrammatically:

(2) FIG. 1 shows a side view of a work machine in the form of an auto concrete pump with an articulated boom in a working position, and

(3) FIG. 2 shows a block circuit diagram of a controller, and a hydraulic circuit of the work machine which is shown in FIG. 1.

DETAILED DESCRIPTION OF THE DRAWINGS

(4) FIG. 1 shows a diagrammatic side view of a work machine 100 in the form of an auto concrete pump with an (articulated) boom 1 in a working position. The boom 1 conventionally forms a distributor boom for liquid concrete.

(5) In a manner which is known per se, the boom 1 has five boom segments or boom arms which are connected to one another in an articulated manner and can be pivoted about axes which run parallel to one another and at a right angle with respect to a vertical axis of the boom 1. The boom 1 can be unfurled or folded up by means of hydraulic drives 2 to 6 in the form of hydraulic cylinders. Reference is also made to this extent to the relevant specialist literature.

(6) The drawings show the hydraulic cylinders 2 to 6 as single-action hydraulic cylinders for the sake of simplicity. In practice, however, double-action hydraulic cylinders are typically used for the actuation of the boom arms.

(7) In addition to the hydraulic drives 2 to 6, furthermore, a hydraulic rotary drive 17 is provided, by means of which the boom 1 can conventionally be rotated about a vertical axis.

(8) The hydraulic drives 2 to 6 and 17 are conventionally fed with a hydraulic medium, the pressure of which and/or the volumetric flow of which can be set.

(9) The boom 1 has a boom tip 7, on which an end hose 16 is arranged, from which liquid concrete can be discharged during operation. Reference is also made to this extent to the relevant specialist literature.

(10) FIG. 2 diagrammatically shows a block circuit diagram of a controller, and a hydraulic circuit of the work machine 100 which is shown in FIG. 1.

(11) For reasons of simpler illustration, merely the hydraulic drives 2 and 3 from FIG. 1 are shown as consumers by way of example in the hydraulic circuit. It goes without saying that the hydraulic drives 3 to 6 and 17 can be fed or are fed in a corresponding way.

(12) Furthermore, there can be further components, for example consumer valves, pressure relief valves, etc. which, however, are not essential for the description of the principle of the invention. Reference is also made to this extent to the relevant specialist literature or prior art, for example in the form of DE 10 2005 035 981 A1.

(13) The hydraulic circuit has a single pressure generating device or volumetric flow generating device 9 in the form of a motor-operated hydraulic pump 9 which conveys hydraulic oil from a tank 19 into a feed line or supply line 8. A pivotable adjusting member 18 is provided to set a volumetric flow which is conveyed into the supply line 8 by means of the hydraulic pump 9.

(14) The supply line 8 branches into two feed lines to the hydraulic drives 2 and 3, a valve 12 and an actuable proportional valve 13 being arranged in the path between the hydraulic consumer 2 and the supply line 8, and a valve 14 and an actuable proportional valve 15 being arranged correspondingly in the path between the hydraulic consumer 3 and the supply line 8.

(15) The valves 12 and 14 bring about that a pressure which drops at the proportional valves 13 and 15 is approximately constant, with the result that a volumetric flow through the proportional valves 13 and 15 is substantially dependent on the opening cross section of the proportional valves 13 and 15. The elements 12 to 15 form a feed device.

(16) Pressure sensors 20 and 21 detect a hydraulic pressure in the hydraulic drives 2 and 3.

(17) Furthermore, an optional pressure sensor 22 is provided which measures a supply pressure pV which is generated by means of the hydraulic pump 9.

(18) The controller of the work machine has a computing unit 11. The computing unit 11 is connected to the pressure sensors 20, 21 and 22, and evaluates the sensor signals which are supplied by the pressure sensors 20, 21 and 22. The computing unit 11 actuates the proportional valves 13 and 15 and the adjusting member 18.

(19) Furthermore, the controller of the work machine 100 has a setting device 10 which is operatively connected to the computing unit 11. The setting device 10 can be configured, for example, as a control lever which can be adjusted, for example, in three main actuating directions with the output of control signals to the computing unit 11. A desired movement direction R and a desired speed v of the boom tip 7 can be specified by means of the setting device 10.

(20) According to the invention, the computing unit 11 is configured to predictively calculate a respective required pressure or pressure gradient and/or a respective required volumetric flow or volumetric flow gradient for those hydraulic drives 2 to 6 which are required for the desired movement direction R and the desired speed v.

(21) After the predictive calculating of the pressure and/or the volumetric flow, the computing unit 11 actuates the adjusting member 18 in such a way that a supply pressure pV is generated suitably in a manner which is dependent on the predictively calculated pressures, and/or a supply volumetric flow QV is generated suitably in a manner which is dependent on the predictively calculated volumetric flows.

(22) Subsequently, the computing unit actuates the proportional valves 13 and 15 in such a way that the hydraulic drives (here, 2 and 3 by way of example) which are required for the desired movement direction R and the desired speed v are supplied with the hydraulic medium at a respective feed pressure pS1 and pS2, respectively, and/or a respective feed volumetric flow QS1 and QS2, respectively, in such a way that the boom tip 7 moves in the desired movement direction R at the desired speed v.

(23) In the case of the determining of the necessary supply pressure pV in the computing unit 11, a highest load pressure under the respective predictively calculated pressures can be determined, the supply pressure pV being generated in a manner which is dependent on the determined highest load pressure.