Method for operating a hydraulic system of a working machine

Abstract

The invention relates to a method for operating a hydraulic system of a working machine with a hydraulic fluid supply system (2) and one or more hydraulic consumers (4) which are connected to the hydraulic fluid supply system via a control valve arrangement (6) in order to be supplied with hydraulic fluid. The hydraulic fluid supply system and / or the control valve arrangement are controlled by means of a control algorithm (20) based on specifications (22) for desired movements of the one or more consumers. The control algorithm is parameterized by one or more parameters which can be changed during operation of the hydraulic system, wherein several sets of parameter values ​​are given for the one or more parameters.When a toggle command (41) is received indicating that the parameter values ​​of a new set of multiple sets of parameter values, which is different from a current set, are to be used, while in the control algorithm the parameter values ​​of the current set of multiple sets of parameter values ​​are being used, a toggle operation is performed in which the parameter values ​​used in the control algorithm are changed to the parameter values ​​of the new set.

Description

[0001] The present invention relates to a method for operating a hydraulic system of a working machine as well as a computing unit and a computer program for carrying out the method. Background of the invention

[0002] Construction machines, such as excavators or wheel loaders, can be equipped with a hydraulic drive system that powers the movement of machine components, such as boom elements, via hydraulic actuators (e.g., hydraulic cylinders and / or hydraulic motors). These actuators are supplied with hydraulic fluid by a hydraulic pump via a control valve assembly, which allows for the control of the flow rate to the actuators. The hydraulic pump and / or the control valve assembly are controlled, in particular, by a control algorithm based on specifications for the desired movements of the actuators. In the case of manual control by a machine operator, these specifications for desired movements can be determined based on control signals generated by a user interface (e.g., a joystick).Similarly, within the framework of an automatic control system, e.g. for the implementation of an assistance function, the specifications for desired movements of consumers can be determined by an automatic control function. Disclosure of the invention

[0003] According to the invention, a method for operating a hydraulic system of a working machine, as well as a computing unit and a computer program for carrying out the method, are proposed, comprising the features of the independent claims. Advantageous embodiments are the subject of the dependent claims and the following description.

[0004] The invention relates to a hydraulic system of a working machine, comprising a hydraulic fluid supply system and one or more hydraulic consumers connected to the hydraulic fluid supply system via a control valve arrangement to receive hydraulic fluid. The hydraulic fluid supply system and / or the control valve arrangement are controlled by a control algorithm based on specifications for desired movements of the one or more consumers. The control algorithm is parameterized by one or more parameters that can be changed during operation of the hydraulic system, and several sets of parameter values ​​are predefined or available for the one or more parameters. The invention utilizes the measure of switching between different parameter sets during operation of the hydraulic system according to a switching command (e.g., a signal or a message).

[0005] This measure enables the use of different parameter values ​​for different operating modes, whereby the sets of parameter values ​​can be adapted to the corresponding operating modes.

[0006] The switching command is generated, for example, by a user interface or an automatic control function. It can also be generated based on a signal or message from the user interface or the automatic control function. In the first case (user interface), the parameter switching occurs in response to a corresponding request from the operator of the machine. In the second case (automatic control function), the automatic control function triggers the parameter switching, for example, to set parameter values ​​that are advantageous for its operation.The automatic control function itself can be triggered by the operator via a user interface or can be triggered automatically, for example, when it is recognized, based on the specifications (which are initially based on operator input), that a specific section, the execution of which is implemented by the automatic control function, has been reached in a repeated work process.

[0007] After triggering the automatic control function, it generates the specifications for the desired movement for at least one or even all of the consumers.

[0008] The switch command contains, in particular (e.g., in the case of more than two sentences), information about which sentence to switch to (e.g., an identifier of the sentence).

[0009] For example, the control algorithm includes a filter and / or processing function for each of the specifications for desired movements of one or more consumers, each of which has at least one filter and / or processing parameter that is included in the one or more parameters. For example, a filter and / or processing parameter can be a cutoff frequency of a frequency filter (e.g., high-pass, low-pass, or band-pass).

[0010] For example, the control algorithm includes a control mechanism, where one or more parameters of the control mechanism are included within the one or more parameters. For example, the parameters include a proportional parameter (e.g., gain factor) and / or an integral parameter (e.g., reset time) and / or a differential parameter (e.g., lead time).

[0011] According to one embodiment, the multiple sets of parameter values ​​include at least one first set, which is to be used when the specifications for desired movements of one or more consumers are generated by an automatic control function, and include at least one second set, which is to be used when the specifications for desired movements of one or more consumers are generated by a user interface, wherein the control algorithm includes a control element that includes a control element with proportional gain (e.g., P, PI, PID element, etc.), wherein a gain factor of the control element is a parameter of one or more parameters, and wherein the gain factor in the at least one first set is larger in absolute value than in the at least one second set.A higher amplification factor results in a more rigid and / or immediate behavior of the machine, which is typically desirable for automatic control functions, while human operators typically prefer a less rigid behavior.

[0012] According to one embodiment, the parameters are changed in respective transitions during the switching process. These transitions are selected from an instantaneous (or immediate) transition, in which the respective parameter is changed to the parameter value of the new set without taking on an intermediate value, and a non-instantaneous transition, in which the respective parameter is changed to the parameter value of the new set over a certain period of time, taking on one or more intermediate values ​​within that period. Whether an instantaneous or non-instantaneous transition is used for a parameter can be predetermined or determined during operation, for example, depending on certain conditions. A non-instantaneous transition can, for example, be a stepwise or continuous change in the parameter value. The time period can be, for example,in the range of 1 s to 20 s, especially in the range of 5 s to 20 s, or from 1 s to 10 s, especially in the range of 5 s to 10 s.

[0013] According to one embodiment, the transitions between different parameters are independent of each other. For example, at least one parameter can have an instantaneous transition, while at least one other parameter can have a non-instantaneous transition. In particular, the transitions (i.e., their timing or start time) can have independent time delays from the time the switching command is received, and these delays can differ for different parameters.

[0014] According to one embodiment, parameter transitions occur instantaneously when the switching command is generated by an automatic control function. This ensures that the new parameters are used when the automatic control function is active. For example, the automatic control function can generate the switching command as soon as the execution of the functionality it implements begins, such as a specific operation of the machine (e.g., leveling a surface with a wheel loader or bulldozer) or a segment thereof. The start of this execution can be triggered by the automatic control function itself or by an operator input captured via a user input device.

[0015] According to one embodiment, during the switching process, at least one parameter is checked to see if a respective condition is met, and the transition of that parameter is carried out in response to the condition being met. This can, for example, prevent unexpected behavior of the consumers from the operator's perspective.

[0016] If the condition is not met, according to one embodiment, the transition for at least one parameter either does not occur until the condition is met, or it occurs as a non-instantaneous transition. The first option can prevent unexpected behavior of the consumers from the operator's perspective. This is advantageous, for example, if the switching command was generated automatically by an automatic control function. The second option can achieve a gradual change in the behavior of the consumers from the operator's perspective. This is advantageous, for example, if the switching command was generated by the operator using a user interface.

[0017] According to one embodiment, the condition includes the requirement that at least one of the specifications for desired movements of one or more consumers is a speed specification and is equal to zero or less than a threshold value. This embodiment allows the parameter transitions to occur while the respective consumers are at rest, so that no unexpected change in the consumer's behavior occurs during a consumer movement, such as an unexpected increase in speed.

[0018] According to one embodiment, the condition check for at least one parameter is omitted during the switching process, and the parameter transitions occur instantaneously, particularly if the switching command was generated by an automatic control function or based on a signal or message from the automatic control function. Whether the switching command was generated by an automatic control function can be indicated, for example, in the switching command itself or by a separate signal or message.

[0019] A computing unit according to the invention, e.g. a control unit of a mobile working machine or of a hydraulic system of a mobile working machine, is, in particular in terms of programming, equipped to carry out a method according to the invention.

[0020] Implementing a method according to the invention in the form of a computer program or computer program product with program code for carrying out all method steps is also advantageous, as this incurs particularly low costs, especially if an executing control unit is already available for other tasks. Suitable data carriers for providing the computer program are, in particular, magnetic, optical, and electrical storage media, such as hard drives, flash memory, EEPROMs, DVDs, etc. Downloading a program via computer networks (Internet, intranet, etc.) is also possible.

[0021] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawing.

[0022] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or on their own, without leaving the scope of the present invention.

[0023] The invention is schematically illustrated in the drawing using exemplary embodiments and is described in detail below with reference to the drawing. Character description Fig. Figure 1 shows a flowchart of a process according to an embodiment of the invention. Fig. Figure 2 shows an exemplary control and regulation structure according to an embodiment of the invention. Detailed description of the drawing

[0024] Fig. Figure 1 shows a flowchart of a process according to an embodiment of the invention.

[0025] The method concerns a control algorithm for the hydraulic system of a machine. The control algorithm is executed, for example, by a control unit of the machine or the hydraulic system. The control algorithm is parameterized by one or more parameters (i.e., the parameters have specific parameter values) that can be changed during operation of the hydraulic system, for example, by writing or programming new values ​​into respective memory locations or registers, which are then read and used by the control algorithm. Several sets of parameter values ​​are provided for each parameter. For example, a separate set may be provided for different operating modes of the machine. The parameter values ​​of two different sets may be the same for one or more, but not all, parameters.It is therefore assumed that two sentences each have a different parameter value for at least one parameter.

[0026] The hydraulic system, or drive system, comprises a hydraulic fluid supply system, for example, with a hydraulic pump and a motor that drives it, one or more hydraulic consumers (e.g., hydraulic cylinders and / or hydraulic motors), and a control valve assembly. The one or more hydraulic consumers (also referred to simply as consumers) are connected to the hydraulic fluid supply system via the control valve assembly to receive hydraulic fluid (i.e., hydraulic fluid, especially hydraulic oil). The control valve assembly regulates the flow rate of hydraulic fluid to and from the consumers. The hydraulic fluid supply system provides an appropriate flow rate of hydraulic fluid to the control valve assembly and, via this, to the consumers. The hydraulic fluid supply system and / or the control valve assembly is, respectively,are controlled by means of the control algorithm based on specifications for desired movements of one or more consumers.

[0027] It is assumed that the control algorithm uses the parameter values ​​of one set (referred to as the current set) of the multiple sets of parameter values, or in other words, that the hydraulic system is operated while the control algorithm uses the parameter values ​​of the current set of the multiple sets of parameter values.

[0028] In an optional step 100, a switch command is generated, particularly through a user interface or an automatic control function, indicating that the parameter values ​​of a new set of parameters, different from the current set, are to be used. A switch command could, for example, be a specific voltage signal or a message sent via a fieldbus that connects various elements of the machine for data communication.

[0029] In step 110, the switching command is received. This occurs while the parameter values ​​of the current set are being used in the control algorithm.

[0030] In step 120, a switching operation is triggered or performed in response to the switching command, in which the parameter values ​​used in the control algorithm are changed to the parameter values ​​of the new set. During the switching operation, the parameters are changed, particularly in the respective transitions. The transitions are selected (e.g., predefined for each parameter) or are selected (e.g.,depending on the existence of certain conditions and / or depending on which sets the switching process takes place) from an instantaneous transition in which the respective parameter is changed to the parameter value of the new set without taking on an intermediate value (between the parameter value of the current set and the parameter value of the new set), and a non-instantaneous transition in which the respective parameter is changed to the parameter value of the new set over a certain period of time, whereby the parameter takes on one or more intermediate values ​​(successively in time) within the period of time.

[0031] In an optional step 130 (which may be part of the switching process), it is checked whether the switching command was generated by an automatic control function. If so (i.e., if the switching command was generated by an automatic control function), the parameter values ​​are changed as an instantaneous transition in step 135.

[0032] If the switching command was not generated by an automatic control function, or if step 130 is not performed, an optional step 140 (which may be part of the switching operation) checks whether a respective condition is met for at least one parameter (of the one or more parameters). If this is the case (i.e., if the condition is met), the transition of the at least one parameter takes place in step 143, in particular as an instantaneous transition. If the at least one parameter includes several parameters, the conditions for different parameters can be different, and the corresponding steps can be independent of each other. That is, steps 140, 143, and 145 are performed independently for each of the at least one parameter.For example, at one point in time the condition may be met for one parameter, so that step 143 is carried out immediately, and for another parameter the condition may not be met, so that for this step 143 is carried out later or step 147 is carried out.

[0033] If the condition is not met for at least one parameter, the transition can be delayed until the condition is met (i.e., the condition is checked repeatedly until it is met), or the transition for the at least one parameter can be performed as a non-instantaneous transition in step 147.

[0034] Other configurations of the switching process (step 120) are also possible. For example, the transitions of the parameter values ​​can be predetermined (without further checks). Furthermore, the transitions of the parameter values ​​can be predetermined for each ordered pair of sentences.

[0035] With the possible exception of step 100, the procedure is computer-implemented and is carried out, for example, by a computing unit, such as a control unit of the machine or the hydraulic system. The computing unit can also execute the control algorithm and / or the automatic control function.

[0036] Fig. Figure 2 shows an exemplary control and regulation structure according to an embodiment of the invention.

[0037] The previously described hydraulic system is depicted, comprising a hydraulic fluid supply system 2 (illustrated as a hydraulic pump), one or more hydraulic consumers 4 (e.g., a hydraulic cylinder), and a control valve assembly 6 (e.g., a valve block). Arrows indicate the flow of hydraulic fluid from the hydraulic fluid supply system 2 to the control valve assembly 6 and to the hydraulic consumer 4.

[0038] Furthermore, functional modules or modules are shown which implement the control of the pressure medium supply system 2 and the control valve arrangement 6, as well as a method according to the invention. Different symbols are used in the figure for modules that are present once and multiple times; a first symbol 8 is used for modules that are present multiple times, e.g., once for each consumer, and a second symbol 10 is used for modules that are present only once.

[0039] Various user interfaces or input elements of a user interface are also shown. These include a mode selection element 12, a joystick 14, and an activation button 16. The mode selection element 12 and / or the activation button 16 can, for example, be implemented as individual switches on a touchscreen. The mode selection element allows the operator to choose one of several modes, such as performance mode, eco mode, standard mode, etc.

[0040] The pressure medium supply system 2 and the control valve arrangement 6 are controlled by a control algorithm 20 based on specifications 22 for desired movements, in particular movement speeds, of the consumers. These specifications 22 for desired movements of the consumers are determined either by an automatic control function 24 (e.g., an assistance function) or from operating signals of the joystick 14. In the latter case, the automatic control function 24 forwards the operating signals for the consumers and stores them only briefly in case the automatic control function is manually activated, so that it knows the current operating signals to ensure a continuous transition.It is also conceivable that the automatic control function evaluates the operating signals to recognize specific work processes or sections thereof, for which the automatic control function triggers its own activation. Manual activation is carried out by the operator of the machine using the activation button 16, which, for example when pressed, generates an activation signal.

[0041] Regarding the control valve arrangement 6, the control algorithm 20 in module 25 determines a corresponding control signal for the control valve arrangement 6 for each consumer based on its input, e.g., for a control valve that influences the flow rate of hydraulic fluid to the respective consumer. Module 25 determines a control signal based on input such as a desired movement speed of a hydraulic cylinder, the amplitude of which corresponds, for example, to the deflection of a control piston of the control valve connected to the respective consumer. The control valve arrangement 6 is actuated by the control signal determined by module 25.

[0042] Regarding the pressure medium supply system 2, the control algorithm 20 determines a corresponding maximum pressure for each consumer in module 26 based on its specifications, and a corresponding volume flow rate for each consumer in module 28. In module 30, the maximum pressure is selected from the maximum pressures of the consumers, which, for example, represents a setpoint pressure. In module 32, the sum of the volume flow rates of the consumers is calculated, with this sum volume flow rate representing, for example, a setpoint volume flow rate. In module 34, a control signal for the pressure medium supply system 2 is determined from the values ​​specified in modules 30 and 32, for example, a swivel angle for a variable displacement pump. The pressure medium supply system 2 is controlled by the control signal determined by module 34.

[0043] A mode management module 40 receives a requested mode from the operator, detected by the mode selection element 12 and / or by the automatic control function 24, and translates the input for the downstream parameter management modules 42 into a switching command 42. This can be a copy of the requested mode or a value from a table that specifies a mapping between the requested mode and the sets of parameter values.

[0044] The parameter management modules 42 (two parameter management modules are shown as examples, but it could just as easily be only one that manages all sets of parameter values) set parameters of modules 26 and 28. For example, the parameter management modules 42 store several sets of parameter values ​​for the respective set parameters. In response to the switch command 42, which includes information about the new set of parameter values ​​to be applied, according to the requested mode, the parameter management modules 42 change the parameter values ​​of modules 26 and 28 in a switch operation, which is described above, e.g., in connection with Fig. 1, was described.

[0045] The parameter management modules 42 can continue to receive the control signals generated by the joystick 14, for example to determine whether a setting for a consumer is equal to zero or close to zero, in order to perform the aforementioned, e.g. in connection with Fig. 1. to be able to check the conditions mentioned. It may also be provided that the parameter management modules 42 receive a suppression signal 44 from the automatic control function 24, which indicates that, if necessary, the checking of the conditions should be suppressed and the parameters should be changed immediately.

[0046] For example, in the figure, parameter values ​​of parameters in modules 26 and 28 are changed. Alternatively or additionally, parameter values ​​of parameters in at least one of modules 25, 30, 32, or 34 could of course be changed.

Claims

[1] Method for operating a hydraulic system of a working machine comprising a pressure medium supply system (2) and one or more hydraulic consumers (4) which are connected to the pressure medium supply system (2) via a control valve arrangement (6) in order to be supplied with pressure medium, wherein the pressure medium supply system (2) and / or the control valve arrangement (6) are controlled by means of a control algorithm (20) based on specifications (22) for desired movements of one or more consumers (4), wherein the control algorithm (20) is parameterized by one or more parameters which are changeable during the operation of the hydraulic system, wherein several sets of parameter values ​​are given for the one or more parameters, the procedure comprehensively: Operating the hydraulic system, wherein the control algorithm (20) uses the parameter values ​​of a current set of the multiple sets of parameter values; Receiving (110) a toggle command (41) indicating that the parameter values ​​of a new set of several sets of parameter values, which is different from the current set, are to be used; Performing (120) a switching operation in response to the switching command (41), in which the parameter values ​​used in the control algorithm are changed to the parameter values ​​of the new set; Operating the hydraulic system, wherein the parameter values ​​of the new set of multiple sets of parameter values ​​are used in the control algorithm (20). [2] Method according to claim 1, wherein the switching command (41) is generated by a user interface (12) or based on a signal or message from the user interface (12). [3] Method according to one of the preceding claims, wherein the switching command (41) is generated by an automatic control function (24) or based on a signal or message from the automatic control function (24). [4] A method according to any of the preceding claims, wherein the multiple sets of parameter values ​​include at least one first set to be used when the specifications (24) for desired movements of one or more consumers (4) are generated by an automatic control function (24), and include at least one second set to be used when the specifications (24) for desired movements of one or more consumers are generated by a user interface (12); wherein the control algorithm (20) includes a control that includes a proportional element, wherein a gain factor of the proportional element is a parameter of one or more parameters, and wherein the gain factor in the at least one first set is larger in absolute value than in the at least one second set. [5] Method according to one of the preceding claims, wherein during the switching process (120) the parameters are changed in respective transitions; wherein the transitions are selected or are selected from an instantaneous transition in which the respective parameter is changed to the parameter value of the new set without taking on an intermediate value in the meantime, and a non-instantaneous transition in which the respective parameter is changed to the parameter value of the new set over a certain period of time, wherein the parameter takes on one or more intermediate values ​​within the period of time. [6] Method according to claim 5, wherein the transitions of different parameters are independent of each other. [7] Method according to one of claims 5 or 6, wherein, when the switching command (41) was generated by an automatic control function (24), the parameter transitions take place as instantaneous transitions. [8] Method according to one of claims 5 or 6, wherein during the switching process (120) it is checked (140) for at least one parameter whether a respective condition is met; and wherein in response to the fact that the condition is met, the transition of the at least one parameter is carried out (143). [9] Method according to claim 8, where, if the condition is not met, the transition for at least one parameter does not occur until the condition is met; or where, if the condition is not met, the transition for at least one parameter is non-instantaneous (147). [10] Method according to claim 8 or 9, wherein the condition includes that at least one of the specifications (22) for desired movements of the one or more consumers (4) is equal to zero or is less than a threshold value in magnitude; wherein the at least one of the specifications for desired movements is a speed specification. [11] Method according to one of claims 8 to 10, wherein, when the switching command (41) was generated by an automatic control function (24) or was generated based on a signal or message of the automatic control function (24), the checking (140) of the condition for the at least one parameter is prevented in the switching process (120) and the transitions of the parameters are in particular instantaneous. [12] Method according to one of the preceding claims, wherein the control algorithm (20) for each of the specifications (22) for desired movements of the one or more consumers includes a filter and / or processing function, each of which has at least one filter and / or processing parameter included in the one or more parameters. [13] Computing unit comprising a processor configured to perform the method according to any of the preceding claims. [14] Computer program comprising instructions which, when the program is executed by a computer, cause it to execute the method according to claims 1 to 12. [15] Computer-readable data carrier on which the computer program according to claim 14 is stored.

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