Abstract
Hydraulic axial piston unit having a rotational group for driving or being driven by a driving shaft, and a tiltable displacement element for adjusting the displacement volume of the rotational group. The rotational group includes a rotatable cylinder block in which working pistons are mounted reciprocally moveable in cylinder bores for conveying hydraulic fluid from a kidney-shaped inlet port to a kidney-shaped outlet port on a valve segment. At least two control ports are located on the valve segment each between the respective circumferential ends of the kidney-shaped inlet port and the outlet port. The control ports can be brought sequentially in fluid connection with the cylinder bores when the cylinder block is rotating. At least one hydraulic fluid injector is connected fluidly to one control port, for sequentially injecting pressurized hydraulic fluid via the control port into the passing cylinder bores. Via the other control port hydraulic fluid can be drained from passing cylinder bores.
Claims
1. A method for conrolling the displacement volume of a hydraulic axial piston unit comprising: a rotational group for driving or being driven by a driving shaft, and a displacement element tiltable for adjusting the displacement volume of the rotational group, wherein the rotational group comprises a rotatable cylinder block in which working pistons are mounted reciprocally moveable in cylinder bores for conveying hydraulic fluid from a kidney-shaped inlet port to a kidney-shaped outlet port located on a valve segment of the hydraulic axial piston unit, said hydraulic axial piston unit further comprising: at least two control ports each located on the valve segment between the respective circumferential ends of the kidney-shaped inlet port and the kidney-shaped outlet port, wherein the control ports can be brought sequentially in fluid connection with the cylinder bores when the cylinder block rotates, the method comprising the following steps: injecting pressurized hydraulic fluid via one control port by means of a hydraulic fluid injector into the passing cylinder bores, draining hydraulic fluid via the other control port from the passing cylinder bores.
2. The method according to claim 1, further comprising the step of: processing commands of a control unit or an operator by means of an electronic control unit (ECU) having a microcontroller for adapting the timing and/or pressure and/or the amount of hydraulic fluid for being injected via the first control port into the passing cylinder bores, in order to control the pressure in the cylinder bores for controling the displacement volume of the hydraulic axial piston unit.
3. The method according to claim 1, further comprising the steps of: sensing of at least one operational parameter of the hydraulic axial piston unit by means of a sensor selected from a group of sensors comprising at least a tilt angle sensor, a shaft position sensor, a pressure sensor, a flow sensor, a rotational speed sensor, a temperature sensor, a direction sensor, a torque sensor, an acceleration sensor or any other sensor capable to monitor at least one operational parameter of the hydraulic unit; transmitting the sensed operational parameter to the electronic control unit (ECU); processing the transmitted operational parameters for adapting the timing and/or pressure and/or the amount of hydraulic fluid for injecting via one of the first control port and draining from the other control port into/from the passing cylinder bores.
4. The method according to claim 3, further comprising the step of: continuously monitoring the operational parameters of hydraulic axial piston unit in order to smoothen pressure steps between the kidney-shaped inlet port and the kidney-shaped outlet port and vice versa, and/or for controlling the pressure in the cylinder bores.
5. A hydraulic axial piston unit comprising: a rotational group for driving or being driven by a driving shaft, and a tiltable displacement element for adjusting the displacement volume of the rotational group, wherein the rotational group comprises a rotatable cylinder block in which working pistons are mounted reciprocally moveable in cylinder bores for conveying hydraulic fluid from a kidney-shaped inlet port to a kidney-shaped outlet port located on a valve segment of the hydraulic axial piston unit, said hydraulic axial piston unit further comprising for the adjustment of the displacement volume: at least two control ports each located on the valve segment between the respective circumferential ends of the kidney-shaped inlet port and the kidney-shaped outlet port, which control ports can be brought sequentially in fluid connection with the cylinder bores when the cylinder block rotates; at least one hydraulic fluid injector connected fluidly to one control port, for injecting pressurized hydraulic fluid via one control port into the passing cylinder bores, and at least one control line connected to the other control port, for draining hydraulic fluid from the passing cylinder bores.
6. The hydraulic axial piston unit according to claim 5, wherein the injector is connected fluidly to the respective control port via a control line.
7. The hydraulic axial piston unit according to claim 5, wherein the injector is connected fluidly to both control ports via two control lines connected to the outlets of a hydraulically, electro-mechanically or pneumatically operable two-position switching valve, wherein the switching valve selects in each position one of two control line for injecting of pressurized hydraulic fluid by means of the injector and the other control line for draining hydraulic fluid from the other control port.
8. The hydraulic axial piston unit according to claim 5, wherein at each control port a separate hydraulic fluid injector is provided, for injecting pressurized hydraulic fluid via the associated control port, wherein hydraulic fluid can be drained from the respective other control port.
9. The hydraulic axial piston unit according to claim 5, wherein the valve segment comprises more than one kidney-shaped inlet port and/or more than one kidney-shaped outlet port, wherein between the respective circumferential ends of each kidney-shaped inlet ports or kidney-shaped outlet ports, respectively, control ports are located for injecting pressurized hydraulic by means of hydraulic fluid injectors.
10. The hydraulic axial piston unit according to claim 5, wherein pressurized hydraulic fluid can be supplied to the at least one injector by means of a high pressure pump.
11. The hydraulic axial piston unit according to claim 5, wherein at least one bypass line with an orifice located therein connects the at least one control port with one of the kidney-shaped inlet port or the kidney-shaped outlet port upstream or downstream of the control port.
12. The hydraulic axial piston unit according to claim 11, wherein the high pressure pump is a mechanically, hydraulically or electrically driven positive displacement pump of the reciprocating- or the rotary-type of construction.
13. The hydraulic axial piston unit according to claim 5, wherein the hydraulic fluid injector can be actuated electro-mechanically, hydraulically or pneumatically.
14. The hydraulic axial piston unit according to claim 5, wherein the hydraulic fluid injector can be a quick reacting switching valve or a hydraulic fluid injector analogous to the ones used in the automotive industry for fuel injection.
15. The hydraulic axial piston unit according to claim 5, wherein the actuation of the injectors is controllable via an electronic control unit (ECU) comprising a microcontroller, and being connected to at least one sensor selected from a group of sensors comprising at least a tilt angle sensor, a shaft position sensor, a pressure sensor, a flow sensor, a rotational speed sensor, a temperature sensor, a direction sensor, a torque sensor, an acceleration sensor or any other sensor capable to monitor at least one operational parameter of the hydraulic unit.
16. The hydraulic axial piston unit according to claim 5, wherein the hydraulic piston unit is a hydraulic axial piston unit being adjustable to positive and/or negative tilt angles.
17. The hydraulic axial piston unit according to claim 5, wherein the displacement element is biased into an initial position by means of an elastic force, in which the displacement volume of the rotational group is at maximum, minimum or at zero.
18. The hydraulic axial piston unit according to claim 5, wherein the hydraulic unit is useable in open or closed hydraulic circuits.
19. The hydraulic axial piston unit according to claim 18, wherein the hydraulic unit is used for a hydraulic system showing a closed hydraulic circuit, and wherein the high pressure pump is used in parallel as a charge pump for the hydraulic circuit.
20. The hydraulic axial piston unit according to claim 5, wherein the injectors and/or the high pressure pump compensates leakages in a hydraulic working or propel application which is supplied with pressurized hydraulic fluid by a hydraulic axial piston unit.
21. A hydraulic system for a hydraulic propel application having at least one hydraulic axial piston unit according to claim 5.
22. The method according to claim 1, applicable to a hydraulic system comprising a plurality of hydraulic axial piston units, further comprising the steps of: injecting hydraulic fluid via a first control port of a first hydraulic axial piston unit and subsequently injecting hydraulic fluid to a different hydraulic axial piston unit via one of its corresponding control ports, thereby: draining hydraulic fluid via a control line from the respective corresponding other control ports.
23. The method according to claim 22, further comprising the step of: monitoring the plurality of hydraulic axial piston units by means of a plurality of sensors and a sensor signal processing system control unit; commanding the hydraulic fluid injectors individually, in order to provide hydraulic axial piston unit displacement control for each single hydraulic axial piston unit.
24. The method according to claim 21, further comprising the step of: injecting hydraulic fluid via at least one additional control port located between the circumferential ends of a plurality of kidney-shaped inlet or outlet ports on a valve segment.
25. The method according to claim 21, further comprising the step of: sensing the system pressure in the working lines of the hydraulic axial piston unit for detecting pressure waves and peaks immanent to the operation of the hydraulic axial piston unit; determing the timing of injection hydraulic fluid into the cylinder bores passing at least one control port such that system immanent waves and peaks in system pressure are reduced, or even eliminated.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] In the following and by the help of the attached Figures, preferred embodiments of the inventive injection system for the controlling of hydraulic axial piston units are shown exemplarily. How-ever, the invention is not limited to the embodiments shown below. Further—even if not described—different embodiments can be combined or modified within the capabilities of a person with ordinary skills in the art, and without leaving the scope of the inventive idea. The Figures show:
[0036] FIG. 1 is a basic embodiment of the inventive in a schematic view;
[0037] FIG. 2 is a schematic plane view of a valve plate;
[0038] FIGS. 3a to 3d are examples for injection pressure-over-rotation-angle diagram(s);
[0039] FIG. 4 is a second embodiment of the inventive injection system;
[0040] FIG. 5 is a third embodiment of the inventive injection system;
[0041] FIG. 6 is a forth embodiment of the inventive injection system;
[0042] FIG. 7 is a sixth embodiment of the inventive injection system; and
[0043] FIG. 8 is a seventh embodiment of the inventive injection system.
DETAILED DESCRIPTION
[0044] FIG. 1 shows a basic embodiment of the inventive injection system for hydraulic axial piston pumps. The hydraulic axial piston pump 1, shown in FIG. 1, is, mere exemplarily, a hydraulic axial piston pump of the swashplate type of construction. The hydraulic axial piston pump 1 comprises a casing 10 in which a rotational group 2 is housed for driving or being driven by a driving shaft 8. The driving shaft 8 is rotationally fixed to a cylinder block 3. Within the rotational cylinder block 3 working pistons 6 are distributed circumferentially in cylinder bores 5 around the axis 9 of the driving shaft 8. By means of the settable tilt angle of the axis of the swashplate 4 with respect to the axis 9 the stroke of working pistons 6 can be set/adjusted, i.e. controlled, and thereby the displacement volume of the hydraulic axial piston unit 1. At the opposite end of cylinder block 3 at the bottom end of cylinder block 3, a valve plate 20 is located with its correspondent kidney-shaped inlet port 21 and kidney-shaped outlet port 22. In this embodiment according to the invention the valve segment 20 is realised as a separate valve plate 20 located between the cylinder block 3 and the casing 10 which is closed by an end cap 19. A skilled person knows that the valve plate 20 can also be an integral part of the housing 10, or in other embodiments this hydraulic fluid conducting part of the housing 10 can be configured like an end cap 19 showing the valve plate functionality. All these and similar embodiments are covered by the invention and denominated as valve segment 20 on which the kidney-shaped inlet and outlet ports (21, 22) as well as the control ports (23) are located.
[0045] The exemplarily hydraulic axial piston pump shown in FIG. 1 can be easily operated as a hydraulic axial piston motor just by changing the inlet port with the outlet port, as it is well known by a person skilled in the art. The same applies to the application of the invention to other axial piston units which are known in the art.
[0046] For explanatory purposes only, the valve plate 20 is shown again on the right side of FIG. 1, and is also shown in FIG. 2 as a more detailed plane view. Here the kidney-shaped inlet port 21 as well as the kidney-shaped outlet port 22, can be identified as inlet, respectively as outlet port for conveying hydraulic fluid via the high pressure line 14 and low pressure line 15. Needless to say for a skilled person, that the inlet port 21 is interchangeable with the outlet port 22 as well as high pressure line 14 is interchangeable with low pressure line 15. This depends on the operational purpose for which the hydraulic axial piston unit 1 is provided for. Between the two kidney-shaped ports 21 and 22, control ports 23 are arranged.
[0047] In this exemplary embodiment, a control port 23 is connected via a control line 27 with an injector 25 for injecting hydraulic fluid under injection pressure at the (upper) control port 23 into the passing cylinder bore 5. A further control line 27 is connected to the other control port 23 for draining hydraulic fluid from the passing cylinder bore 5 towards a high pressure pump 30, e.g. or to an area of the hydraulic axial piston unit 1 where low pressure is present, e.g. a tank 200 or to casing 10. In this embodiment the injection pressure higher than the pressure present in the cylinder bore 5 which can be injected via the upper control port 23 into a cylinder bore 5 is provided by a high pressure pump 30 which is arranged in a closed circuit connecting the upper control port 23 with the lower control port 23. A skilled person will consider without difficulties that the high pressure pump 30 can be operated in an open circuit as well, and that the draining control line 27 can drain hydraulic fluid directly to casing 10 or to a tank 200, from which high pressure pump 30 can suck hydraulic fluid for pressurization.
[0048] It can be seen also from FIG. 1 that, in case, when hydraulic fluid under injection pressure is injected via the upper control port 23 into the cylinder bore 5, the corresponding working piston 6 will be moved towards the swashplate 4, so that the angle of tilt of the swashplate 4 will be reduced. At the same time the working piston 6 at the other dead centre (here the bottom dead centre) facing the other control port 23 will be moved further towards the inside of its correspondent cylinder bore 5. Consequently the upper dead centre (the most internal position of working piston 6) is moved/adjusted in the same amount, however in the opposite direction as the lower dead centre of the working piston 6 in cylinder bore 5. With changing the angle of tilt of the swashplate 4, both stroke limits of the working pistons 6 are changed and the displacement volume of the hydraulic axial piston pump 1 is reduced thereby.
[0049] The hydraulic axial piston unit 1 shown in FIG. 1 is at its maximum displacement volume, i.e. showing the maximum angle of tilt. This tilt angle can be changed by injecting hydraulic fluid via the lower control port 23 as described above. However, in particular, for hydraulic axial piston units having two conveying directions, the initial position of such a hydraulic unit would be normally at a tilt angle equal to zero; this means that the displacement volume is zero as the stroke of the working pistons 6 is zero also. From this zero-angle position it is imaginable, at least for a skilled person that any change of the swashplate angle can be performed either by injecting hydraulic fluid via one of the two control ports 23. When injecting hydraulic fluid via one of the two control ports 23 into one correspondent cylinder bore 5, the same volume is displaced via the other control port 23, as the displacement element—here the swashplate 4—is tilted out of its neutral position. Thereby the injection pressure and amount of hydraulic fluid is controlled by an electronic control unit (ECU) having a microcontroller 110. By means of the exemplarily shown speed sensor 43, angle sensor 41 and pressure sensor 42 the main operational parameters can be monitored. The sensor signals are transmitted to the ECU by means of signal lines 31. Correspondingly via signal line 31, e.g., electronic signals processed by the ECU as commands for injecting hydraulic fluid are guided—in this embodiment—to injector 25 in order to achieve the inventive control of the displacement volume by means of injection of hydraulic fluid in the passing cylinder bore 5 (see also FIG. 2).
[0050] FIG. 2 shows schematically a valve plate 20 in concept of an example for a valve segment 20 according to the invention. Here the kidney-shaped inlet port 21, the kidney-shaped outlet port 22, and the control ports 23 are depicted in solid lines, wherein the cylinder bores 5 rotating during operation of the hydraulic axial piston unit 1 around rotational axis 9 are depicted in dashed lines. As can be seen from FIG. 2 the two control ports 23 are located on the valve segment (here valve plate 20) between the circumferential end of the kidney-shaped inlet and outlet ports 21 and 22. With reference numbers 61 and 62 the respective dead end positions of the working pistons 6 are indicated regarding its location with regard to the angle of rotation cp. Even though the control ports 23 in FIG. 2 are shown as circular bores, the invention covers also to realise them with an elongated section or kidney-shaped section as shown, e.g., in FIG. 1. Further, the circumferential ends of the kidney-shaped inlet and outlet ports 21 and 22 and/or the control ports 23 can show any suitable shape or distance between them in order to provide an optimised functioning for the inventive idea. By means of timely variable injecting pressurized hydraulic fluid via one control port 23 and draining hydraulic fluid via the other control port 23 a kind of flexible extension of the kidney-shaped inlet and outlet port is performed depending on the time point of injection chosen. A person with relevant skills in the art will recognise that the time point for injecting or draining of hydraulic fluid from the control ports 23 before or after the respective dead centre will influence the displacement volume of the hydraulic axial piston unit and will on-stroke or de-stroke it.
[0051] FIGS. 3a to 3d show bore-pressure over rotation-angle diagrams in which the bore pressure course is shown exemplarily for different operational situations and purposes. From these diagrams it can be seen that the starting points for injecting as well as the end points to stop injection into one single cylinder bore 5 passing one of the control ports can be selected flexibly corresponding to the operational requirements. This can be done especially by an electronic control unit having a microcontroller 110, e.g. Further it can be seen from the diagrams of FIGS. 3a to 3d that also the gain in pressure inside the cylinder bore 5 can be controlled with the inventive hydraulic fluid injection system when using an appropriate electronic control unit.
[0052] FIG. 3a shows exemplarily a course of injection pressure for on-stroking, e.g. a hydraulic axial piston pump 1, i.e. increasing the strokes of the working pistons 6, as at least in one cylinder bore 5 at or after bottom dead centre (bdc) hydraulic fluid is injected, hence before this cylinder bore 5 enters at φ.sub.2 in overlap with kidney-shaped inlet port 21. At the same time—even not shown in the diagram of FIG. 3a—the same amount of hydraulic fluid is drained from another cylinder bore 5 located in the area of rotation angle φ.sub.3 and φ.sub.4. Thus, the working piston 6 of the injected cylinder bore 5 is forced to displace its bottom dead centre (bdc) towards the inside of the cylinder block 3, thereby increasing the angle of tilt and increasing the displacement volume of the hydraulic axial piston unit 1.
[0053] FIG. 3b show, mere exemplarily too, the injection pressure course for de-stroking the hydraulic axial piston pump 1, as at least in one cylinder bore 5 hydraulic fluid is injected after this cylinder bore 5 leaves at φ.sub.3 its overlap with kidney-shaped outlet port 22, At the same time—even not shown in the diagram of FIG. 3a—the same amount of hydraulic fluid is drained from another cylinder bore 5 located in the area of rotation angle φ.sub.1 and φ.sub.2. Thus, the working piston 6 of the injected cylinder bore 5 is forced to displace its upper/top dead centre (tdc) towards the inside of the cylinder block 3, thereby reducing the angle of tilt and reducing the displacement volume of the hydraulic axial piston unit 1.
[0054] FIGS. 3c and 3d show a cylinder bore pressure profile over rotation angle for holding a hydraulic axial piston unit on stroke and compensate dynamic disturbances of the hydraulic axial piston pump 1. FIG. 3c is an example for low speed operational condition, and FIG. 3d shows an cylinder bore pressure profile over rotation angle (solid line) for holding on-stroke a high speed rotating rotational group avoiding thereby pressure peaks as these commonly occur in the state of the art. The dashed line in FIG. 3d indicates the correspondent cylinder bore pressure profile according to the state of the art showing these pressure peaks. By means of the inventive hydraulic fluid injection via at least one control port, these pressure peaks can be smoothened. A person with skills in the art also derives from these bore-pressure over rotation-angle diagrams that with adapting/controlling the timing of the injection pressure at the corresponding injection kit moments on the valve plate can be reduced significantly as big pressure differences/steps, especially between the low pressure kidney-port and the high pressure kidney-port can be damped/smoothened/equalized by the inventive hydraulic fluid injection into at least one control port 23 being in fluid communication with a cylinder bore 5.
[0055] FIG. 4 shows an inventive hydraulic unit 1 in a further embodiment of the inventive injection system. In this embodiment only one injector 25 is used in combination with a switching valve 35 enabling the possibility of alternative injection of pressurized hydraulic fluid to one of the two control ports 23. In the situation of the switching valve 35 depicted in FIG. 4 the upper control port 23 is the injection port and the lower control port 23 is the draining port from which hydraulic fluid is drained to the high pressure pump 30. Hence, as it can be derived further from FIG. 4, by means of switching the switching valve 35 into its second position, the injection port changes with the draining port. In this case only one signal line 31 from the electronic control unit to the injector 25 is necessary for controlling/monitoring the inventive hydraulic axial piston unit 1 in all operational conditions, i.e. to on-stroke or de-stroke or to change the direction of conveying or to improve the running characteristics of the hydraulic axial piston unit 1.
[0056] FIG. 5 further shows another optional embodiment for improving the running characteristics of the hydraulic axial piston unit 1 by connecting at least one of the control ports 23 with one of the beneath located kidney-shaped inlet or outlet port 21 or 22 upstream or downstream of the control port 23 by means of a bypass line 28 with an orifice 29 connected therein. A person skilled in the art detects that such an optional bypass line 28 with the therein located orifice 29 can be applied to all embodiment according to the invention and is not limit to the one shown in FIG. 5. By means of this bypass line 28 with the therein located orifice 29 the pressure raise or drop between the pressure level at the control port 23 to the pressure present in kidney-shaped inlet or outlet port 21 or 22 can be dampened or smoothened such that, for instance, pressure waves generated by big pressure differences are avoided or at least reduced in their magnitude.
[0057] For this exemplary inventive controlling of the hydraulic axial piston unit 1 two separate injectors 25 are provided, one for each control port 23. Accordingly, for each injector 25 a separate command line 31b, 31c from the electronic control unit 110 is provided for commanding the two injectors 25 independently. In FIG. 5 the high pressure pump 30 is capable to provide one of both injectors 25 with hydraulic fluid under injection pressure, wherein the respective other injector 25 is capable to guide drained hydraulic fluid to the entrance (input port) of high pressure pump 30. A person skilled in the art can modify the embodiment shown in FIG. 5 by adding a switching valve 35 as it is used for instance in the embodiment shown in FIG. 4 in order to avoid that high pressure pump 30 has to be changed in its conveying direction when switching from one injector 25 to the other is commanded by ECU 110. A person with skills in the relevant art, will detect easily a lot of other possibilities to select one or the other control line 27, in order to provide only one of the two injectors 25 with hydraulic fluid under injection pressure. Exemplarily draining lines 50 bypass the hydraulic fluid injectors 25, In each draining line 50 a check valve 51 is located in order to drain hydraulic fluid from the control port 23 which is not the hydraulic fluid injection control port; i.e. the draining control port. These draining lines 50 with its respective check valves 51 are not mandatory and depends, e.g. from the type of injectors used in implementation of the inventive hydraulic fluid injection control system.
[0058] A further embodiment of the inventive hydraulic axial piston unit with an inventive injection system is depicted in FIG. 6. The embodiment of FIG. 6 for an inventive injection system differs from the embodiment of FIG. 5 as it uses the system/working pressure as source for the injection pressure, and do not comprise a high pressure pump 30. Accordingly the two injectors 25 are connected via a switching valve 35 with the two kidney-shaped ports 21 and 22 such that both injectors 25 are capable to alternatively inject or drain hydraulic fluid from the control port 23 to which the injector 25 is assigned to. Thereby injection pressure is supplied by the high pressure kidney-shaped port 21 or 22 to one of the two injectors 25, and hydraulic fluid drained from the other injector 25 is guided to the correspondent other low pressure kidney-shaped port 22 or 21.
[0059] With FIG. 7 another example for the implementation of the inventive hydraulic fluid injection controlled hydraulic axial piston unit 1 is shown, which is based on the embodiment of FIG. 5. In this embodiment according to FIG. 6 two more control ports 23 with correspondent hydraulic fluid injectors 25 are located spaced at approximately 90° to each other. The kidney-shaped inlet and outlet ports 21 and 22 are each divided into 2 sub-kidneys. By means of these two additional hydraulic fluid injection locations the cylinder bore pressure profile over the whole circumference of the valve segment 20, here again a valve plate 20 can be controlled at more points in order to reduce kit moments and optimize the running of the hydraulic axial piston unit 1. Following the example shown with FIG. 7 a skilled person derives that also a plurality of more than four hydraulic fluid injectors 25 can be placed on the valve segment 20 in the areas between two partial kidney-shaped inlet and outlet ports 21 and 22 in order to get an even more precise control of the circumferential cylinder bore pressure profile of the hydraulic axial piston unit 1.
[0060] Another part-reduced implementation of the inventive injection system is shown with FIG. 8 in which a hydraulic fluid injector (25) is used which is capable to use the pressure level supplied directly via the systems high pressure lines 14. In this embodiment draininng of hydraulic fluid from the non-injection control port 23 is possible via a bypass line 28 and an orifice 29 located in the bypass line 28, wherein the bypass line 28 is connected to the low pressure kidney-shaped port. This bypass line 28/orifice 29 combination can be realized as a kind of notch in the valve segment 20, for instance.
[0061] Furthermore, a person with skills in the relevant art will detect many more possibilities to optimize the run and adjustment of hydraulic units by manipulating the injection parameters like injection time, gain/decent of injection pressure (bore pressure) over time and/or rotation angle, injection pressure, and/or amount of hydraulic fluid injected by one or more injectors in order to come to an improved control and running behaviour of an inventive hydraulic unit and the hydraulic system, in which the hydraulic unit is used. Hence, all these combinations and variations, which are within the possibilities of a person with relevant skills in the art, are covered by the inventive idea and therefore by the scope of the attached claims.
