Patent Publication Number: US-2023160178-A1

Title: Method for Damping a Movably Mounted Attachment Part of a Machine and the Machine

Description:
This application claims priority under 35 U.S.C. § 119 to patent application no. DE 10 2021 213 085.2, filed on Nov. 22, 2021 in Germany, the disclosure of which is incorporated herein by reference in its entirety. 
     The present disclosure relates to a method for damping a movably mounted attachment part of a machine, wherein the attachment part can be moved by means of a hydraulic cylinder, wherein the hydraulic cylinder is actuated via a hydraulic pump, and to a processing unit and a computer program for the implementation of same, as well as such a machine having an attachment part. 
     BACKGROUND 
     Machines, in particular work machines or other movable or drivable machines, in particular vehicles, can have movable attachment parts which can be moved by means of a hydraulic cylinder. Such attachment parts can be, for example, an excavator arm of an excavator, a front loader of a tractor or the like. 
     When the attachment part moves relative to the rest of the machine, or also for example during the driving of the machine, vibrations of the attachment part can occur which are transferred to the rest of the machine. Compensating for such vibrations is sometimes complex and optionally requires complex torque management or additional components. 
     It is therefore desirable to specify a simple and cost-effective possibility for damping a movably mounted attachment part of a machine. 
     SUMMARY 
     The disclosure relates to a method for damping a movably mounted attachment part of a machine, to a processing unit and to a computer program for implementing same, as well as to such a machine having the features disclosed herein. Advantageous embodiments are the subject matter of the disclosure and the following description. 
     The disclosure relates to machines having a movable attachment part (or add-on device) which can be moved by means of a hydraulic cylinder. The attachment part can be a component of the machine itself, which, however, can be moved relative to the rest of the machine. Examples thereof include an excavator arm of an excavator or a front loader (with a bucket scoop or the like) of a tractor or wheel loader. The hydraulic cylinder is actuated via a hydraulic pump, in particular an electrohydraulic pump, for example in the form of an axial piston pump. In addition, a hydraulic valve, in particular a so-called control valve, can be provided in order to conduct the flow of hydraulic fluid from the hydraulic pump into the load-side (e. g., the bottom) chamber of the hydraulic cylinder to move the attachment part in a direction, counter to a load, e.g., for raising an excavator arm, or into the other, e.g., rod-side chamber of the hydraulic cylinder for moving the attachment part in the other direction, e.g., for lowering the digger arm. The relevant other chamber should then be connected to a tank. 
     To damp the movably mounted attachment part or movements of the attachment part and vibrations caused thereby, a (current) value of a pressure in the load-side chamber of the hydraulic cylinder is recorded or measured, specifically during a measurement phase. This value is then fed as a measured value, for example, to an executing processing unit where it is received. In addition, current position information of the attachment part, from, for example, location sensors and/or position sensors, can be taken into account. In the measurement phase, it must be ensured that precisely no vibration is present, for example when the machine and the attachment part are at a standstill. 
     Then, the hydraulic pump is controlled to adjust the pressure in the load-side chamber of the hydraulic cylinder to the measured value as setpoint value, and during operation of the machine. This serves to damp the movably mounted attachment part. In particular, the hydraulic pump should be set up in both directions, that is to say for conveying into the load-side chamber and out of the chamber; it should therefore be a so-called two-quadrant pump. 
     In other words, a pressure regulator of the hydraulic pump is thus adjusted to the static load pressure in the load-side, e.g. bottom, chamber (or bottom) of the hydraulic cylinder. The hydraulic pump will then keep the pressure in the load-side chamber constant. In this case, any dynamic changes in the pressure, such as those caused by a movement of the attachment part, in particular relative to the rest of the machine, for example as a result of driving the machine, are adjusted by the hydraulic pump. 
     The location or position sensors also make it possible to adapt the pressure setting of the hydraulic pump such that the attachment part can be held in a safe position. In other words, position information of the attachment part, in particular from one or more location or position sensors, is obtained and the setpoint value is adapted as a function of the position information and a predetermined or desired position of the attachment part. 
     Preferably, at least one further component of the machine, in particular a drive, is actuated via the hydraulic pump. In this case, pressure and/or torque changes arising during the adjustment of the pressure in the load-side chamber of the hydraulic cylinder can be taken into account, in particular compensated, during operation of the at least one further component. Thus, the torques introduced by the hydraulic pump, for example into the drive train, do not affect the driving dynamics. They are compensated by appropriate machine management. This applies correspondingly to power output and power consumption. 
     A processing unit according to the disclosure, e.g., a control unit of a work machine or vehicle, is configured, in particular programmatically, to carry out a method according to the disclosure. 
     The disclosure also relates to a machine, in particular a vehicle, having a movably mounted attachment part, which is movable by means of a hydraulic cylinder, wherein the hydraulic cylinder can be actuated via a hydraulic pump, and further having a processing unit according to the disclosure. 
     The implementation of a method according to the disclosure in the form of a computer program or computer program product with program code for carrying out all method steps is also advantageous since this results in particularly low costs, in particular if an executing control unit is also used for further tasks and is therefore present in any event. Suitable data carriers for providing the computer program are, in particular, magnetic, optical, and electric storage media, such as hard disks, flash memory, EEPROMs, DVDs, and others. It is also possible to download a program via computer networks (Internet, Intranet, etc.). 
     Further advantages and embodiments of the disclosure can be found in the description and the accompanying drawing. 
     Of course, the features mentioned above and those still to be explained below can be used not only in the respectively specified combinations, but also in other combinations or alone, without departing from the scope of the present disclosure. 
     The disclosure is illustrated schematically in the drawing on the basis of an exemplary embodiment and is described in detail below with reference to the drawing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG.  1    schematically shows a machine according to the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1    schematically shows a machine  100  according to the disclosure in a preferred embodiment, on the basis of which a method according to the disclosure is also to be explained below in a preferred embodiment. 
     The machine  100 , for example, has a movable attachment part  110  designed as an excavator arm, which is movable by means of a hydraulic cylinder  122 . The hydraulic cylinder in turn is actuated via a hydraulic pump  130 , in particular an electrohydraulic pump. For this purpose, the hydraulic pump  130 , here an axial piston pump, is connected to a load-side, here the bottom, chamber  121  of the hydraulic cylinder via a hydraulic valve  140  designed as a control valve. The rod-side chamber  122  is then connected to the tank  150 . Although the connections can also be connected differently by the control valve, the situation mentioned is to be used for the following method. For this purpose, the hydraulic valve is to be moved to the right from the position shown. 
     Furthermore, a location or position sensor  112  for detecting position information of the attachment part  110  is provided, a further location or position sensor  114  on a bearing (or frame), likewise a pressure sensor  124  for detecting a pressure P in the bottom chamber  121  and a pivot angle sensor  132  for detecting a pivot angle of the hydraulic pump. Likewise, a rotational speed sensor for detecting the rotational speed can be integrated there. The sensors are all connected to a processing unit  160  designed as a control unit, so that the corresponding measured values can be received there. For example, the location or position sensors allow particularly good control of the location and of the load pressure. 
     For example, a current value of the pressure p in the bottom chamber  121  is recorded during a measurement phase and stored as a measured value in the processing unit  160 . This measured value results from a weight force F G  which is exerted on the hydraulic cylinder by the attachment part  110 . 
     The hydraulic pump  130  is then controlled to adjust the pressure in the bottom chamber  121  to the measured value as the setpoint value, specifically during operation of the machine  100 . This ensures that the force F Z  exerted on the attachment part by the pressure in the bottom chamber  121  and the hydraulic cylinder, which force counteracts the weight force F G , remains constant, in any case as much as possible. As a result, when the weight force F G  is reduced briefly due to a movement of the attachment part, as a result of which the pressure in the bottom chamber  121  is reduced, for example, this pressure is increased by the hydraulic pump. This prevents a vibration of the attachment part, since the hydraulic cylinder or the rod is tracked. The same applies conversely.