Hydraulic pump for a hydrostatic drive and hydrostatic drive

Abstract

A hydraulic pump having an adjustable delivery volume for pressure medium supply to a hydrostatic load in a pressure-controlled manner is disclosed, having a trajectory planning unit by means of which a target trajectory having a flatness and a time derivative thereof can be planned from a desired pressure of the hydraulic pump and can be transmitted to a pre-control unit of the hydraulic pump, the pre-control unit comprising an inverse model of the hydraulic pump by means of which a control target value for an adjustment device of the hydraulic pump can be determined from the target trajectory and the time derivative thereof and with which the adjustment device can be controlled. Furthermore, a hydrostatic drive device having a hydraulic pump and a hydrostatic load supplied with pressure medium by the hydraulic pump is disclosed.

Description

Technical Field

[0001] The present invention relates to a hydraulic pump according to the preamble of claim 1 and a hydrostatic drive device, particularly a travel drive device, according to claim 16. Background Technology

[0002] Especially in off-highway applications of hydrostatic drive systems, traction or torque-based driving strategies have proven to be operator-friendly. Here, the operator presets traction or torque requirements using an HMI interface. The resulting traction or torque is hydraulically based on the pressure of the pressure medium supplied by a hydraulic pump. In the case of rotating loads, the traction or torque of the hydrostatic load or hydraulic motor coupled to the output device is obtained based on pressure and the absorption volume. Conversely, traction or torque-based drive can be achieved by means of pressure control or regulation.

[0003] This type of travel drive device is illustrated in the applicant's published document DE 102014224337A1. Here, control is implemented by using a preset target torque value at the output device as a control parameter. Based on the preset, a target time variation curve or target trajectory can be planned not only from the target value but also from the time derivative of that target value, which can be implemented by the drive device mechanism. The trajectory is then input into a complex inverse model of the entire hydraulic circuit, namely the hydraulic pump and hydraulic motor. Thus, the control unit plans the target trajectory of the adjustment parameter to achieve the target value. The adjustment elements of the travel drive device are then manipulated based on the target trajectory. This is a high-quality control. However, the underlying model is complex. Summary of the Invention

[0004] In contrast, the objective of this invention is to provide a hydraulic pump for a drive device that enables the pressure for the drive device to be set with reduced consumption while still being closely guided by a force or torque preset. Another objective of this invention is to provide a drive device whose force or torque can be set with reduced consumption and closely guided by a force or torque preset.

[0005] The first task is accomplished by a hydraulic pump having the features of claim 1, and the second task is accomplished by a drive device having the features of claim 16.

[0006] Advantageous modifications of the invention are described in the dependent claims.

[0007] A first hydraulic press (hereinafter referred to as a hydraulic pump), which can operate as a hydraulic pump and is coupled to a drive unit, has an adjustable delivery volume and is equipped with a pressure medium for supplying a hydrostatic load to the drive unit, especially the traveling drive unit, in a pressure-controlled manner. The hydraulic pump is particularly a primary unit of an axial piston pump constructed in a swashplate configuration. The load is particularly a hydraulic motor that can be coupled to the output device of the drive unit. The hydraulic pump has a device for trajectory planning. This device allows for the planning of a target trajectory with flatness characteristics and its time derivative for a required pressure. These target trajectories are input into a pre-control device of the hydraulic pump, which includes an inverse model of the hydraulic pump. By means of this device and the inverse model, control target values ​​for the adjustment device of the hydraulic pump can be obtained based on the target trajectory and its time derivative, and the adjustment device can be controlled thereby. According to the invention, at least one load-dependent disturbance parameter is fed into the pre-control unit. Preferably, these disturbance parameters can be detected, assessed, or learned by control.

[0008] Therefore, compared to the cited prior art, it is possible to omit modeling the entire load and integrating it into the inverse model. Thus, the inverse model has lower complexity. To achieve high-quality control despite this, i.e., to maintain a small deviation between the pressure and the required value, load disturbance parameters are instead fed into the pre-control unit. A hydraulic pump is thus implemented, by which the pressure for the drive device can be set with reduced costs while still closely guided by a force or torque preset.

[0009] In one modified embodiment, the absorption volume of the load, especially the hydraulic motor, can be controlled, detected, or determined by control, i.e., known.

[0010] The time constant of trajectory planning depends in particular on the usage, that is, on the specific application of the hydraulic pump in the specific drive unit.

[0011] As an alternative or supplementary solution, input saturation and / or state saturation can be considered in the device used for trajectory planning to calculate the corresponding trajectory.

[0012] The inverse model is based on a reduced-order model of the differential equations of the hydraulic pump, consisting of differential equations describing the regulating device and differential equations describing pressure establishment (pressure establishment equations). If the regulating device consists of a hydraulic actuator, particularly a hydraulic cylinder, and a hydraulic valve for loading the regulating pressure medium onto the actuator (as described further below), the dynamics of valve regulation can be neglected. The differential equations of the regulating device are then derived from the corresponding force balances at the valve body and the piston of the actuator. Alternatively, valve dynamics can be considered.

[0013] In one modified embodiment, at least one load-dependent disturbance parameter is the detected or determined volumetric flow rate of the pressure medium or the time derivative of that volumetric flow rate. Alternatively, both of the aforementioned parameters, namely the volumetric flow rate of the pressure medium and its time derivative, can be fed in as disturbance parameters.

[0014] In one modified approach, the inverse model includes a volumetric flow rate model or a volumetric flow rate balancing mechanism, whose output determines, in particular, geometric parameters of the target delivery volume of the hydraulic pump. In the case of an axial piston pump employing a swashplate configuration, this parameter is, for example, the pivot angle of the swashplate.

[0015] According to a preferred modification, the following objects are set as inputs to the volumetric flow rate model or volumetric flow rate balancing mechanism: at least one detected or derived from the rotational speed and parameters of the hydraulic pump, the first time derivative of the target trajectory, and the load pressure medium volumetric flow rate as a load-dependent disturbance parameter that can be fed in.

[0016] In one modified version, the inverse model has a volumetric flow rate time derivative model or a volumetric flow rate time derivative balancing mechanism. The output of this inverse model is the time derivative of the target delivery volume of the hydraulic pump, particularly the geometric parameters, especially the time derivative of the pivot angle mentioned earlier.

[0017] Preferably, the inputs to the volumetric flow rate time derivative model or the volumetric flow rate time derivative balancing mechanism are at least one detected or derived from the rotational speed and parameters of the hydraulic pump, the first-order time derivative of the target trajectory, the trajectory with a second-order time derivative depending on the target trajectory, and the time derivative of the pressure medium volumetric flow rate of the load as a load-dependent disturbance parameter that can be fed in.

[0018] If the inverse model includes a leakage model in a modified embodiment, the quality of the pre-control can be further improved. This leakage model preferably considers at least the target trajectory and its first-order time derivative as input. The output is preferably the leakage pressure medium volumetric flow rate, particularly the leakage pressure medium volumetric flow rate of a hydraulic circuit consisting of at least a hydraulic pump and at least one hydraulic motor, especially a hydrostatic drive device; and the time derivative of the leakage pressure medium volumetric flow rate. In one modified embodiment, this leakage pressure medium volumetric flow rate is then input into a volumetric flow rate model or a volumetric flow rate balancing mechanism.

[0019] As an alternative or supplementary solution, the time derivative of the volumetric flow rate of the leaking pressure medium can be input into the volumetric flow rate time derivative model or the volumetric flow rate time derivative balancing mechanism to further improve the quality of pre-control.

[0020] In one modification of the hydraulic pump, a regulating device is used to achieve better quality because it takes into account model inaccuracies, model uncertainties, and unknown interference parameters, and can more reliably reduce the deviation between the pressure and the required pressure.

[0021] To this end, a first comparison mechanism is provided, through which a first difference is obtained from the target trajectory (minuend) and the detected pressure (subtrahend). This first difference is then input to the regulating device.

[0022] The adjustment device preferably reflects an adjustment strategy, such as allowing the traction / torque required by the operator to be applied to the drive wheels of the drive unit.

[0023] For this reason, a PID control device was specifically designed.

[0024] The PID controller is preferably designed with anti-saturation in mind, considering both the saturation of the target value and the saturation of the geometric parameters (especially the pivot angle) that determine the delivery volume of the hydraulic pump. Saturation is preferably activated when the parameter (pivot angle) reaches a defined critical value stored in the pre-control section, due to the restricted pivot angle. Additionally, the PID controller can be reset when the parameter (pivot angle) exceeds zero, since the integral part of the PID controller depends on the valve used. The desired pressure characteristics are described by a linearized function z and its first and second time derivatives.

[0025] To process the output of the regulating device and to feed it back to the pre-control unit, a second comparison mechanism is provided in one modified embodiment. The inputs to the second comparison mechanism are the second-order time derivative (minuend) of the target trajectory (mentioned earlier) and the output of the regulating device (subtrahend). The output of the second comparison mechanism is the aforementioned related trajectory. In this way, the second-order time derivative of the target trajectory is changed from the output of the regulating device to the related trajectory. Specifically, the output of the PID regulating device is calculated with the highest-order time derivative of the target trajectory at the required pressure, followed by a new input to the inverse model. The advantage of this structure is that the inverse model takes into account changes in the gain of the regulating system. Therefore, for example, only a small increase in the control target value and pivot angle is needed for high-speed hydraulic pumps, while a larger increase is needed for low-speed pumps.

[0026] As already shown, in a preferred modification, the adjusting device has a hydraulic actuator, particularly a hydraulic cylinder. For this purpose, a hydraulic valve that can be controlled by a control current and is electromagnetically operable is provided. Depending on the control of this hydraulic valve, the actuator can be loaded with a volume of adjusting pressure medium having an adjusting pressure.

[0027] Therefore, the target adjustment pressure can be derived from the characteristic curve of the hydraulic pump, which is set in the inverse model. This characteristic curve depicts the correlation between the target adjustment pressure and the hydraulic pump's rotational speed, target trajectory, and parameters (especially the pivot angle) determining the target delivery volume of the hydraulic pump. Conversely, the target adjustment pressure medium volume can be derived from the actuator's model, which reflects the correlation between the target adjustment pressure medium volume and the time derivative of parameters (especially the pivot angle) determining the target delivery volume.

[0028] In one modified version, the hydraulic valve is electromagnetically actuated, and the inverse model includes a model of the valve through which the target control current of the valve can be determined based on the target regulating pressure and the volume of the medium under the target regulating pressure. The valve model specifically reflects the force balance of magnetic force, hydrodynamic force, regulating pressure, and, if necessary, spring force acting on the valve piston.

[0029] The hydrostatic drive has a hydrostatic load that can be coupled to the output device of the drive; and has a hydraulic pump designed according to the aspects described above, which is fluidly connected to the load in a hydraulic circuit and can be coupled to the drive motor of the drive.

[0030] Specifically, the drive unit is a travel drive unit, and the load is a hydraulic motor. Therefore, for the travel drive unit, a driving strategy based on traction or torque can be achieved without adjustment, providing high quality and reproducibility of the torque or traction required by the operator. Of course, quality and reproducibility can also be improved through the adjustment device and its modifications as described earlier.

[0031] Hydrostatic driving systems are particularly suitable for off-highway applications, especially mobile work machinery and construction machinery. At least one secondary unit, particularly a secondary unit with a constant or adjustable absorption volume, is configured as an axial piston motor with a slant-shaft structure. The two units (primary and secondary units) are connected in series hydrostatically. A hydraulic pump in the drive unit is driven by an internal combustion engine, an electric energy storage device, or a hydraulic pressure storage device, converting mechanical power into hydraulic power. At least one secondary unit converts hydraulic power into mechanical power at the output side of the drive unit. This process can also be reversed, such as braking at least one secondary unit at the output side. The hydraulic circuits of the primary and secondary units can be implemented as open or closed loops. In the case of an open loop, the low-pressure side of the unit is connected to a pressure-balanced tank; in the case of a closed loop, the low-pressure sides of the primary and secondary units are directly connected to each other. Both circuits preferably use pressure relief valves to prevent excessive pressure. To improve the efficiency of the drive unit, a power branch can be provided, in which a mechanical power path is provided in parallel with the hydrostatic section of the drive unit. Adjustments to the discharge volumes of the primary and secondary units can be made individually or coupled to each other. Generally, a rotational speed proportional to the volumetric flow rate of the pressurized medium is generated on the secondary side. Attached Figure Description

[0032] The following three figures illustrate in detail an embodiment of a drive device according to the invention, which includes a hydraulic pump according to the invention. Wherein:

[0033] Figure 1 A hydrostatic drive device configured as a travel drive device according to one embodiment is shown;

[0034] Figure 2 It shows according to Figure 1 A simplified block diagram of the hydraulic pump of the drive unit, along with its devices for trajectory planning, pre-control, and regulation, and

[0035] Figure 3 It shows according to Figure 2 A detailed block diagram of the hydraulic pump. Detailed Implementation

[0036] according to Figure 1 The hydrostatic propulsion drive 1 includes a drive motor 2; a first hydraulic press 4 (hereinafter referred to as the hydraulic pump), coupled to the drive motor and designed as a swashplate axial piston pump with an adjustable delivery volume or pivot angle; and a second hydraulic press 8 (hereinafter referred to as the hydraulic motor), coupled to the output device 6 and designed as a swashplate axial piston motor with a constant displacement or shaft angle. In the illustrated embodiment, the hydraulic pump 4 and the hydraulic motor 8 are fluidly connected in a closed hydraulic circuit via working lines 10 and 12. The hydraulic motor 8 is coupled to the output device 6 via a transmission mechanism 14. In the illustrated embodiment, the output device is an axle with wheels 16.

[0037] The drive unit 1 has a device 18 for detecting geometric parameters that determine the delivery volume of the hydraulic pump 4. In the aforementioned configuration, these parameters are, for example, the pivot angle α of the swashplate of the hydraulic pump 4.

[0038] Furthermore, the device 20 is used to detect the pressure p of the hydraulic pump 4, more precisely, to detect the pressure difference Δp between the working lines 10 and 12 on the hydraulic pump 4. Based on the arrangement in the hydraulic circuit and with negligible flow losses, the pressure p decreases by the same amount as the pressure difference Δp on the hydraulic motor 8. Additionally, the hydraulic pump 4 has an adjustment device 22 for adjusting the pivot angle α of the hydraulic pump and thus the delivery volume.

[0039] In the illustrated embodiment, the adjustment device consists of an electromagnetically operable hydraulic valve (not shown in exploded view) and an actuator (also not shown in exploded view) designed as a double-acting hydraulic cylinder that can be loaded by the hydraulic valve with a regulating pressure medium.

[0040] Adjustment is particularly well-known as electric direct adjustment or ET adjustment. The pressure medium volumetric flow rate of the hydraulic pump 4 can be determined based on the control current i that controls the hydraulic valve. des This allows for stepless adjustment. Here, valves, especially pressure-reducing valves, can be provided for each adjustment direction (particularly if the hydraulic pump 4 is capable of rotation or reversal due to its zero delivery volume). This is in conjunction with the control current i. des The actuator is loaded using a pressure medium adjusted in a proportional relationship. Based on the characteristic curve of hydraulic pump 4, a specific control current i is applied. des The resulting pivot angle and the conveying volume determined therefrom depend on the rotational speed n. P And the pressure difference Δp.

[0041] The hydraulic pump 4 has a control unit 24 according to the invention, which includes means for trajectory planning of the pressure difference and its time derivative, and means for feeding in disturbance parameters with a hydraulic motor. The device for pre-controlling the hydraulic pump 4 by trajectory planning and the device for regulating pressure are described. Here, the control unit 24 is signal-connected to the controller 26 of the drive unit 2.

[0042] Figure 2 The general structure of control unit 24 and a first overview of the signal flow of this control unit are shown. Therefore, control unit 24 has an input terminal 28, which can be connected, for example, to an HMI interface, through which the required pressure difference Δp can be transmitted. des (In short, the required pressure Δp) des The preset value (Δp) is transmitted to control unit 24. des The traction force F, representing the driving drive 1, is required by the operator via the HMI. des Or the required output torque M des The intensive state parameter. Therefore, this pressure is a control parameter or adjustment parameter that needs to be set as precisely as possible by the control unit 24. Figure 2 This pressure is input to a device for trajectory planning (Trajektorienplanung, trajectory planning unit) 30, which has a pressure Δp. des，filt The target trajectory and its two time derivatives As a flat, linearized output. Three target trajectories Δp des，filt , The input is given to the device for pre-control (Vorsteuerung, pre-control unit) 32, wherein the highest-order time derivative is... It can be changed in advance by the device used to adjust 34, which will be explained in detail below.

[0043] The device for pre-control 32 includes an inverse model of hydraulic pump 4, comprising the hydraulic pump having according to Figure 1 The valve and actuator adjustment device 22. The pressure medium volumetric flow rate and its time derivative of the hydraulic motor 8 are fed as disturbance parameters into the device for pre-control 32. The output of the pre-control 36 provides the control current i. des The control current is used to control the valve of the adjustment device 22, and thus the actuator is loaded with the regulating pressure medium, and the pivot angle α of the hydraulic pump 4 is adjusted.

[0044] The pressure Δp is detected and fed back as a subtraction to the first comparison mechanism 38, where it is compared with the pressure Δp. des，filt The target trajectory is calculated.

[0045] The deviation obtained here is input to a device configured as a PID controller for adjusting 34. The output of this device is then connected as a subtrahend to a second comparator 40, where it is compared with the highest-order time derivative of the pressure. The target trajectory is calculated. The result, as the target trajectory of the change in the highest-order time derivative of the pressure, is then input into the device for pre-control 32, causing a changing control current ides. This changing control current is used to control the valve of the adjustment device 22. This results in a new pressure Δp.

[0046] Figure 3 The device used for pre-control 32 and the model and signal flow stored therein were decomposed more precisely. Therefore, the inverse model of hydraulic pump 4 is stored in the device used for pre-control 32.

[0047] This inverse model includes characteristic curve 42 of hydraulic pump 4, in which the characteristic curve is related to the rotational speed ω of hydraulic pump 4. P Pressure Δp des，filt The required target trajectory and the necessary target pivot angle α of hydraulic pump 4. P，soll The necessary target adjustment pressure p of the actuator of the adjustment device 22 is preserved. x，soll .

[0048] In addition, an actuator model 44 is set up, in which the time derivative with respect to the target pivot angle of the hydraulic pump 4 is calculated. The necessary target adjustment pressure medium volume q of the actuator of the adjustment device 22 is preserved. stell，soll .

[0049] Characteristic curve 42 and actuator model 44 are models of components close to the drive unit, and in particular represent the drive force, pressure, and adjustment pressure acting on the swashplate of hydraulic pump 4. The necessary target adjustment pressure p is derived from this. x，soll The value and the actuator target adjustment pressure medium volume q stell，soll The input is entered into the valve model 46 of the valve in the adjustment device 22.

[0050] This represents the force balance acting on the valve body. Target adjustment pressure p x，soll The piston area of ​​the actuator is input into module 48 for calculating the pressure Fp. The target adjustment pressure is p. x，soll The target adjustment pressure medium volume q of the actuator stell，soll The input is fed into the module 50 of the valve opening cross-section. The module 50 then calculates the spring force F. F and fluid dynamics F jet The sum of these three forces corresponds to the operating force F to be applied to the electromagnet of the valve in adjusting device 22. MAnd the input is fed into the module used to calculate the control current 52, in which the control current i is stored in principle. des Related to the control force F M The characteristic curve.

[0051] In addition, the device for pre-control 32 includes a volumetric flow rate model 54, a volumetric flow rate time derivative model 56, and a leakage model 58.

[0052] Rotation speed ω P The first time derivative of the target trajectory Leakage pressure, medium volumetric flow rate q leck And the pressure medium volumetric flow rate q of the hydraulic motor 8, which serves as an interference parameter. mot The input is fed into the first-mentioned model 54. The result of volumetric flow rate model 54 is the target pivot angle α. P，soll The target pivot angle is input into characteristic curve 42 to adjust the target pressure p. x，soll Perform the aforementioned calculation.

[0053] Rotation speed ω P The highest-order time derivative of the target trajectory that changes after the second comparison mechanism 40. The first time derivative of the target trajectory The time derivative of the leakage pressure medium volumetric flow rate And the time derivative of the pressure medium volumetric flow rate of the hydraulic motor 8, which is used as an interference parameter. This is input into the second model 56 mentioned. The result of the volumetric flow rate time derivative model 56 is the time derivative of the target pivot angle. This is input into actuator model 44 for adjusting the pressure medium volume q to the target. stell，soll Perform the aforementioned calculation.

[0054] Leakage pressure medium volumetric flow rate q leck and its time derivative Based on the leakage model 58 and the target trajectory Δp des，filt and its first time derivative To seek and to provide.

[0055] Models 54, 56, and 58 can be referred to as hydraulic model 60.

[0056] Using the control current i des Operating the valve of the adjusting device 22 generates pressure Δp, as shown in the figure. Figure 2 As already described, this pressure is fed back to the PID controller 34 for the purpose of adjusting the residual deviation.

[0057] A hydraulic pump is disclosed for supplying a pressure medium to a hydrostatic load (especially a hydraulic motor) of a hydrostatic drive device (especially a travel drive device). The hydraulic pump has a control unit with means for trajectory planning of a target pressure of the hydraulic pump and its time derivative, wherein the target trajectory is an input to a pre-control device, in which an inverse model of the hydraulic pump is stored. The inverse model allows the determination of a control target value of an adjustment device of the hydraulic pump based on the trajectory, and thereby allows the adjustment device to be controlled. According to the invention, at least one input to the inverse model is provided for feeding in a load-dependent disturbance parameter.

[0058] Furthermore, a hydrostatic drive device, particularly a travel drive device, is disclosed, having at least one hydrostatic load that can be coupled to the output device of the drive device. The hydrostatic drive device is arranged in a hydraulic circuit together with a hydraulic pump, as mentioned last, and can be supplied with a pressure medium by the hydraulic pump. In this case, at least one state parameter of the load is fed as a disturbance parameter into the pre-control section of the control unit of the hydraulic pump.

Claims

1. A hydraulic pump with adjustable delivery volume for supplying pressure medium to a hydrostatic load (8) in a pressure-controlled manner, the hydraulic pump having a trajectory planning unit (30) by which the required pressure of the hydraulic pump (4) can be controlled. For target trajectories with flatness ( ) and the time derivative of the target trajectory ( , The system plans and transmits the data to the pre-control unit (32) of the hydraulic pump (4), which includes at least the inverse model (42, 44, 46, 60) of the hydraulic pump (4), through which the target trajectory can be determined. ) and its time derivative ( , To obtain the control target value of the adjustment device (22) of the hydraulic pump (4). And thereby enabling control of this adjustment device, characterized in that, At least one disturbance parameter that depends on the load ( , ) is fed into the pre-control unit (32).

2. The hydraulic pump according to claim 1, wherein, At least one load-dependent disturbance parameter is the detected or determined pressure medium volumetric flow rate of the load (8). ) or the time derivative of the volumetric flow rate of the pressure medium ( ).

3. The hydraulic pump according to claim 1 or 2, wherein, The inverse models (42, 44, 46, 60) have a volumetric flow rate model (54), the output of which is a parameter for determining the target delivery volume of the hydraulic pump (4). ).

4. The hydraulic pump according to claim 3, wherein, The input to the volumetric flow rate model (54) is: at least one detected or determined delivery volumetric flow rate of the hydraulic pump (4) or the value on which this delivery volumetric flow rate is based. The target trajectory ( The first time derivative of ) ) and the pressure medium volumetric flow rate of the load (8) as a feedable disturbance parameter that depends on the load. ).

5. The hydraulic pump according to claim 3, wherein, The inverse models (42, 44, 46, 60) have a volumetric flow rate time derivative model (56), the output of which is a parameter for determining the target delivery volume of the hydraulic pump (4). The time derivative of ) ).

6. The hydraulic pump according to claim 5, wherein, The input to the volumetric flow rate time derivative model (56) is: at least one detected or calculated delivery volumetric flow rate of the hydraulic pump (4) or the value on which this delivery volumetric flow rate is based. The target trajectory ( The first time derivative of ) ), depends on the target trajectory ( The second time derivative of ) The trajectory of the load (8) and the pressure medium volumetric flow rate of the load (8) as a feedable disturbance parameter dependent on the load. The time derivative of ) ).

7. The hydraulic pump according to claim 5, wherein, The inverse models (42, 44, 46, 60) include a leakage model (58), the input of which is: the target trajectory ( ) and the first time derivative of the target trajectory ( ), and the output of the leakage model is: leakage pressure medium volumetric flow rate ( ) and the time derivative of the leakage pressure medium volumetric flow rate ( ).

8. The hydraulic pump according to claim 7, wherein, Another input to the volumetric flow rate model (54) is the leakage pressure medium volumetric flow rate ( ).

9. The hydraulic pump according to claim 7, wherein, The other input to the volumetric flow rate time derivative model (56) is the leakage pressure medium volumetric flow rate ( The time derivative of ) ).

10. The hydraulic pump according to claim 1 or 2, comprising an adjusting device (34) by which pressure can be reduced ( ) and the pressure of requirements ( () deviation.

11. The hydraulic pump according to claim 10, having a first comparison mechanism (38), by means of the first comparison mechanism being able to achieve the target trajectory ( ) as the minuend and with the pressure ( The first difference is obtained by using as the subtrahend, where The first difference is the input to the regulating device (34).

12. The hydraulic pump according to claim 10, having a second comparison mechanism (40), the input of which is: the target trajectory as the minuend ( The second time derivative of ) ) and the output of the regulating device (34) as a subtractor, wherein, The output of the second comparison mechanism (40) is the relevant trajectory.

13. The hydraulic pump according to claim 3, wherein, The adjustment device (22) has a hydraulic actuator and can be controlled by a control current ( The hydraulic valve is controlled by [a specific mechanism / operation], and by controlling the hydraulic valve, the volume of the pressure medium can be adjusted. ) and adjusting pressure ( ) to load the executor.

14. The hydraulic pump according to claim 3, wherein, The inverse model (42, 44, 46, 60) includes the characteristic curve (42) of the hydraulic pump (4), which is derived from the rotational speed of the hydraulic pump (4). The target trajectory ( ) and parameters for determining the target delivery volume of the hydraulic pump ( It can determine the target adjustment pressure. ).

15. The hydraulic pump according to claim 13, wherein, The inverse model (42, 44, 46, 60) includes the model (44) of the actuator, which is determined at least based on parameters that determine the target delivery volume. The time derivative of ) It can determine the volume of the target adjusting pressure medium. ).

16. A hydrostatic drive device, which has: At least one hydrostatic load (8), said load being coupled to the output device (6) of said drive device (1); and A hydraulic pump (4) designed according to any one of the preceding claims, the hydraulic pump being fluidly connected to the load (8) in a hydraulic circuit and being coupled to the drive motor (2) of the drive device (1).

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