HYDRAULIC ARRANGEMENT

Abstract

The invention relates to a method (19) of operating a hydraulic arrangement (1) including a mounting base (5), a boom (3) that is pivotably arranged on the mounting base (5), and a Z-kinematics (2) that is arranged on the boom (3). The Z-kinematics (2) tilts a tool attachment device (10), that is pivotably arranged on the boom (3). The boom (3) is moved by a lifting hydraulic piston (7) that is connected to the boom (3) and to the mounting base (5). The Z-kinematics (2) is moved by at least a tilting hydraulic piston (11) that is connected to a lever of the Z-kinematics (2) and to the mounting base (5). On application of an input control command for changing the position of the lifting hydraulic piston (7), a compensation command is automatically generated and applied to the tilting hydraulic piston (11), to essentially maintain the attitude of the tool attachment device (10). The compensation command is generated based on the input control command for the lifting hydraulic piston (7), using a mathematical model of the hydraulic arrangement (1).

Claims

1. A method of operating a hydraulic arrangement comprising a mounting base, a boom that is pivotably arranged on the mounting base, and a Z-kinematics that is arranged on the boom, the Z-kinematics being designed and arranged to tilt a tool attachment device, the tool attachment device being pivotably arranged on the boom, wherein the boom is moved by at least a lifting hydraulic piston that is connected to the boom and to the mounting base, and wherein the Z-kinematics is moved by at least a tilting hydraulic piston that is connected to a lever of the Z-kinematics and to the mounting base, wherein on application of an input control command for changing the position of the lifting hydraulic piston, a compensation command is automatically generated and applied to the tilting hydraulic piston, to essentially maintain the attitude of the tool attachment device, where the compensation command is generated based on the input control command for the lifting hydraulic piston, using a mathematical model of the hydraulic arrangement.

2. The method according to claim 1, wherein the method is applied for a hydraulic arrangement, in particular a hydraulic arrangement comprising a Z-kinematics, that is operated on different sides of a dead centre position thereof, preferably across the dead centre position thereof.

3. The method according to claim 1, wherein the method for operating the hydraulic arrangement, in particular the hydraulic arrangement comprising the Z-kinematics, is performed in a way that the Z-kinematics is operated in a way that a first connecting point of parts of the Z-kinematics may be moved across and/or may be operated on both sides of a straight line that is defined by a second and a third connecting point of parts of the Z-kinematics.

4. The method according to claim 1, wherein a bucket, a fork, a shovel and/or a grasping device is attachable to the tool attachment device and/or in that the hydraulic arrangement forms part of a shovel dozer, a wheel loader, a telescopic wheel loader, a teleloader, a backhoe loader, an excavator and/or a forklift truck.

5. The method according to claim 1, wherein the hydraulic arrangement is arranged on a vehicle and/or in that the mounting base is a vehicle chassis and/or the mounting base is preferably fixedly attached to a vehicle chassis.

6. The method according to claim 1, wherein the input control command is applied by a human operator.

7. The method according to claim 1, wherein the control commands are influenced by at least a sensor signal, in particular a position sensor signal and/or an angle sensor signal.

8. The method according to claim 1, wherein the Z-kinematics comprises a rocking lever and a connecting lever, where the rocking lever is pivotably attached to the boom at a middle section, to the tilting hydraulic piston at a first end section, and to the connecting lever at a second end section thereof; and wherein the connecting lever is connected to the rocking lever at a first end section and to the tool attachment device at a second end section thereof.

9. The method according to claim 1, wherein the method calculates the angle ϕ.sub.1 between the line OE, connecting points O and E, and the line EJ, connecting points E and J, using the formula ${\varphi }_1={\cos }^{-1}\left(\frac{{.Math.\mathrm{JE}.Math.}^2+{.Math.\mathrm{OE}.Math.}^2-{.Math.\mathrm{OJ}.Math.}^2}{2.Math..Math.\mathrm{JE}.Math..Math..Math.\mathrm{OE}.Math.}\right),$ where O is the hinging point of the boom and the mounting base, E is the hinging point of the boom and the tool attachment device, and J is the hinging point of the connecting lever of the Z-kinematics and the tool attachment device.

10. The method according to claim 1, wherein the method calculates the angle ϕ.sub.2 between the line OJ, connecting points O and J, and the line EJ, connecting points E and J, using the formula ${\varphi }_2={\cos }^{-1}\left(\frac{{{.Math.\mathrm{OJ}.Math.}^2+|\mathrm{JE}.Math.}^2-{.Math.\mathrm{OE}.Math.}^2}{2.Math..Math.\mathrm{OJ}.Math..Math..Math.\mathrm{JE}.Math.}\right),$ where O is the hinging point of the boom and the mounting base, E is the hinging point of the boom and the tool attachment device, and J is the hinging point of the connecting lever of the Z-kinematics and the tool attachment device.

11. The method according to claim 1, wherein the method calculates the angle ϕ.sub.3 between the line OJ, connecting points O and J, and the line OE, connecting points O and E, using the formula ${\varphi }_3={\cos }^{-1}\left(\frac{{.Math.\mathrm{OJ}.Math.}^2+{.Math.\mathrm{OE}.Math.}^2-{.Math.\mathrm{JE}.Math.}^2}{2.Math..Math.\mathrm{OJ}.Math..Math..Math.\mathrm{OE}.Math.}\right),$ where O is the hinging point of the boom and the mounting base, E is the hinging point of the boom and the tool attachment device, and J is the hinging point of the connecting lever of the Z-kinematics and the tool attachment device.

12. The method according to claim 1, wherein the compensation command is limited, in particular with respect to its magnitude and/or to its range and/or in that the compensation command is amplified, in particular with respect to its magnitude.

13. A controller device, in particular electronic controller device that is designed and arranged to perform a method according to claim 1.

14. A hydraulic arrangement, comprising a Z-kinematics and a boom, further comprising a plurality of hydraulic actuators, in particular at least a tilting hydraulic piston and at least a lifting hydraulic piston, and a controller device according to claim 13.

15. A working vehicle, comprising a hydraulic arrangement according to claim 14.

16. The method according to claim 2, wherein the method for operating the hydraulic arrangement, in particular the hydraulic arrangement comprising the Z-kinematics, is performed in a way that the Z-kinematics is operated in a way that a first connecting point of parts of the Z-kinematics may be moved across and/or may be operated on both sides of a straight line that is defined by a second and a third connecting point of parts of the Z-kinematics.

17. The method according to claim 2, wherein a bucket, a fork, a shovel and/or a grasping device is attachable to the tool attachment device and/or in that the hydraulic arrangement forms part of a shovel dozer, a wheel loader, a telescopic wheel loader, a teleloader, a backhoe loader, an excavator and/or a forklift truck.

18. The method according to claim 3, wherein a bucket, a fork, a shovel and/or a grasping device is attachable to the tool attachment device and/or in that the hydraulic arrangement forms part of a shovel dozer, a wheel loader, a telescopic wheel loader, a teleloader, a backhoe loader, an excavator and/or a forklift truck.

19. The method according to claim 2, wherein the hydraulic arrangement is arranged on a vehicle and/or in that the mounting base is a vehicle chassis and/or the mounting base is preferably fixedly attached to a vehicle chassis.

20. The method according to claim 3, wherein the hydraulic arrangement is arranged on a vehicle and/or in that the mounting base is a vehicle chassis and/or the mounting base is preferably fixedly attached to a vehicle chassis.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Further advantages, features, and objects of the invention will be apparent from the following detailed description of the invention in conjunction with the associated drawings, wherein the drawings show:

[0033] FIG. 1: an embodiment of a kinematics for a wheel loader in a first position;

[0034] FIG. 2: the embodiment of a kinematics for a wheel loader according to FIG. 1 in a second position;

[0035] FIG. 3: the kinematics of a wheel loader according to FIG. 1 in a third position;

[0036] FIG. 4: a flowchart, illustrating a possible method to actuate a hydraulic kinematics;

[0037] FIG. 5: various definitions of parts, angles, lines and connections of the kinematics according to FIGS. 1 to 3.

DETAILED DESCRIPTION

[0038] FIG. 1 shows a kinematics 1, comprising a Z-kinematics 2 for a wheel loader (not shown) in a first position. In the position shown in FIG. 1, the kinematics 1 is shown in a low position of the boom 3 with a horizontal attitude of the fork 4.

[0039] As it is known in the state of the art as such, the kinematics 1 comprises a boom 3 that is pivotally mounted to the mounting base 5 of the kinematics 1 at hinge point O (see FIG. 5). The mounting base 5 is presently designed to be connected to a vehicle chassis (presently not shown) via a hinge 6 with a vertical axis. This way, the kinematics 1 can be angularly moved parallel to the ground within a certain range.

[0040] The boom 3 can be raised and lowered using a lifting hydraulic piston 7. The hydraulic lifting piston 7 is pivotably connected with one of its end sections to the mounting base 5 at point B (see FIG. 5). With its other end section, the lifting hydraulic piston 7 is pivotably connected to the boom 3 at point C.

[0041] Further, attached to the boom 3, there is a Z-kinematics 2, comprising a rocking lever 8. The rocking lever 8 is rotatably connected to the boom 3 at point F. As can be easily seen from the Figs., point F is located in a middle section of the rocking lever 8, where the position of point F is offset from the exact middle, presently towards point H.

[0042] Further, the rocking lever 9 is rotatably connected to a connecting lever 9 at point G. Point G is—as can be easily seen from the Figs.—located in one of the end sections of connecting levers 9, while the other end section of connecting lever 9 is rotatably connected to tool mount 10 at point J. The tool mount 10 can be used to reversibly connect a tool like a fork 4, a shovel, a bucket and the like.

[0043] The Z-kinematics 2 can be actuated by the tilting hydraulic piston 11. The tilting hydraulic piston 11 is connected with one of its end sections to one end of the rocking lever 8 at point H, whereas it is connected with its other end section to the mounting base 5 at point A.

[0044] Further, the tool mount 10 is pivotably connected to the boom 3 at point E.

[0045] As it is known from the prior art, the boom 3 can be raised or lowered by actuating the lifting hydraulic piston 7, while the tool mount 10 (and consequently the tool attached to it, like a fork 4) can be tilted by an appropriate contraction or expansion of tilting hydraulic piston 11.

[0046] If the kinematics 1 is to be moved from its lower position, as shown in FIG. 1, to an upper position, as shown in FIG. 2, this lifting movement can be performed by an expanding actuation of the lifting hydraulic piston 7. Based on the very design of the kinematics 1, this induces a certain problem. Namely, the lifting movement induced by the lifting hydraulic piston 7 will lead to an attitude change of the fork 4. Presently, the upward movement will lead to a downward tilting of the fork 4, so that the kinematics 1 will end up in the position shown in FIG. 2.

[0047] To avoid this effect, which incurs the possibility that goods (not shown) that are loaded on the fork 4 will fall off the fork when the fork 4 is raised, according to the present disclosure a corrective action is applied to the tilting hydraulic piston 11. This correction is applied automatically by a (electronic) controller (for example single printed board programmable controller), when an operator commands a raising or lowering action. Therefore, in addition to a simple actuation of the lifting hydraulic piston 7, the controller will additionally command an appropriate actuation of the tilting hydraulic piston 11. This way, a lifting actuation with corrections applied will lead to the final position according to FIG. 3: the fork 4 remains in the horizontal position, although the operator manually commands an expansion of the lifting hydraulic piston 7 only.

[0048] For the controller to be able to calculate an appropriate corrective actuation, the controller requires information about the present position of the kinematics 1, in addition to the applied control commands by the operator.

[0049] In the presently shown embodiment, two angle detectors are used for this purpose. The two sensors (not shown) are placed in point F and point O, respectively. They are used to measure angle α (which is the angle between the lines OA and OF), and the angle β (which is the angle between the lines AF and HF).

[0050] It is to be noted that this is just one possible embodiment. (In part) additionally and/or (in part) alternatively, angle detectors may be employed at other positions and/or position detectors, in particular for measuring the position of hydraulic pistons 7, 11 or the like, may be used.

[0051] FIG. 4 shows a basic flowchart 19 of the method to be performed. A controller checks 20 for an input by the operator. If an input is detected, the controller checks for the nature of the command. If an actuation of the tilting hydraulic piston 11 it is commanded, the algorithm jumps 22 directly to step 30, where the command is applied to the appropriate actuators, presently to tilting hydraulic piston 11.

[0052] If a lifting or lowering command is applied, however, the algorithm jumps to step 23, were sensor data by the angle/position sensors is read in.

[0053] Using the positional data and the input command (actuation of lifting hydraulic piston 7), a corrective command 24 is calculated (presently for the tilting hydraulic piston 11). Both commands, i.e. the input command and the correcting command will be handed over to step 30 and applied to the respective hydraulic pistons 7, 11. Afterwards, the algorithm jumps back 31 and repeats.

[0054] The mathematical model that is used for calculating the corrective signal in step 24 of the flowchart 19 is further elucidated by the following equations which refer to the notation illustrated in FIG. 5 in the following. Further, the notation is used that BC denotes the line between points B and C (similar for other points). Further, in the following the cosine rule for the general triangle (non-rectangular triangle) will be used frequently. Further, as it will be obvious to a person skilled in the art, several distances are defined by the mechanical setup of the actuated arrangement, while others will change. In particular, the lengths of the hydraulic pistons 7, 11 are subject to variations. Please also keep in mind that in the presently described embodiment the angles α, β are measured using angular sensors. Certainly, the method can be easily modified if different sensors are used.

[0055] We have the identity β=β′+β″, with β being measured and

[00001]${\beta }^{\prime }={\cos }^{-1}\left(\frac{{.Math.\mathrm{AF}.Math.}^2+{.Math.\mathrm{OF}.Math.}^2-{.Math.\mathrm{AO}.Math.}^2}{2.Math..Math.\mathrm{AF}.Math..Math..Math.\mathrm{OF}.Math.}\right).$

[0056] Using

[00002]${\theta }_5={\cos }^{-1}\left(\frac{{.Math.\mathrm{FC}.Math.}^2+{.Math.\mathrm{EF}.Math.}^2-{.Math.\mathrm{CE}.Math.}^2}{2.Math..Math.\mathrm{FC}.Math..Math..Math.\mathrm{EF}.Math.}\right)-{\theta }_6,$

and assuming that the points H, F and G are arranged directly in line, we can use θ.sub.6=π−(θ.sub.7+β), getting

[00003]${\theta }_7={\cos }^{-1}\left(\frac{{.Math.\mathrm{FC}.Math.}^2+{.Math.\mathrm{FO}.Math.}^2-{.Math.\mathrm{OC}.Math.}^2}{2.Math..Math.\mathrm{FC}.Math..Math..Math.\mathrm{FO}.Math.}\right)-{\beta }^{″}.$

[0057] Knowing these angles, |GE| can be calculated to be

[00004]$.Math.\mathrm{GE}.Math.=\sqrt{{.Math.\mathrm{EF}.Math.}^2+{.Math.\mathrm{FG}.Math.}^2-2.Math..Math.\mathrm{EF}.Math..Math..Math.\mathrm{FG}.Math..Math.\cos \left({\theta }_5\right)}.$

[0058] Since all sides in triangle ΔFGE are known, the remaining angles in the triangle can be calculated.

[00005]${\theta }_1+{\theta }_2={\cos }^{-1}\left(\frac{{.Math.\mathrm{GE}.Math.}^2+{.Math.\mathrm{FG}.Math.}^2-{.Math.\mathrm{FE}.Math.}^2}{2.Math..Math.\mathrm{GE}.Math..Math..Math.\mathrm{FG}.Math.}\right),{\theta }_8+{\theta }_4={\cos }^{-1}\left(\frac{{.Math.\mathrm{JE}.Math.}^2+{.Math.\mathrm{GE}.Math.}^2-{.Math.\mathrm{JG}.Math.}^2}{2.Math..Math.\mathrm{JE}.Math..Math..Math.\mathrm{GE}.Math.}\right),{\theta }_1={\cos }^{-1}\left(\frac{{.Math.\mathrm{JG}.Math.}^2+{.Math.\mathrm{GE}.Math.}^2-{.Math.\mathrm{JE}.Math.}^2}{2.Math..Math.\mathrm{JG}.Math..Math..Math.\mathrm{GE}.Math.}\right).$

[0059] Therefore, θ.sub.2 can be determined. In the following, we have to consider two different cases, since triangle ΔFJE flips at a certain point. Therefore, |OJ| must be calculated using two different cases: [0060] For β≤49.505:

[00006]${\theta }_2={\cos }^{-1}\left(\frac{{.Math.\mathrm{GE}.Math.}^2+{.Math.\mathrm{FG}.Math.}^2-{.Math.\mathrm{FE}.Math.}^2}{2.Math..Math.\mathrm{GE}.Math..Math..Math.\mathrm{FG}.Math.}\right)+{\theta }_1,$

and [0061] for β>49.505:

[00007]${\theta }_2={\cos }^{-1}\left(\frac{{.Math.\mathrm{GE}.Math.}^2+{.Math.\mathrm{FG}.Math.}^2-{.Math.\mathrm{FE}.Math.}^2}{2.Math..Math.\mathrm{GE}.Math..Math..Math.\mathrm{FG}.Math.}\right)-{\theta }_1.Math.d$

[0062] Consequently, |FJ|=√{square root over (|JG|.sup.2+≡FG|.sup.2−2.Math.|JG|.Math.|FG|.Math.cos(θ.sub.2))}.

[0063] Knowing |FJ| we can now calculate θ.sub.10 using the equation

[00008]${\theta }_{10}={\cos }^{-1}\left(\frac{{.Math.\mathrm{FJ}.Math.}^2+{.Math.\mathrm{FE}.Math.}^2-{.Math.\mathrm{JE}.Math.}^2}{2.Math..Math.\mathrm{FJ}.Math..Math..Math.\mathrm{EF}.Math.}\right).$

[0064] Again, due to the fact that triangle ΔFJG flips at a certain point, for calculating |OJ| two cases have to be considered:

[00009]$\mathrm{For}\beta \ge 95:.Math.\mathrm{OJ}.Math.=\sqrt{{.Math.\mathrm{OF}.Math.}^2+{.Math.\mathrm{FJ}.Math.}^2-2.Math..Math.\mathrm{OF}.Math..Math..Math.\mathrm{FJ}.Math..Math.\cos \left({\beta }^{\prime }+{\theta }_7+{\theta }_6+{\theta }_5-{\theta }_{10}\right)},\mathrm{and}\mathrm{for}\beta >95:.Math.\mathrm{OJ}.Math.=\sqrt{{.Math.\mathrm{OF}.Math.}^2+{.Math.\mathrm{FJ}.Math.}^2-2.Math..Math.\mathrm{OF}.Math..Math..Math.\mathrm{FJ}.Math..Math.\cos \left({\beta }^{\prime }+{\theta }_7+{\theta }_6+{\theta }_5+{\theta }_{10}\right)}.$

[0065] Hence, it is possible to determine all angles inside triangle ΔOEJ using:

[00010]${\varphi }_1={\cos }^{-1}\left(\frac{{.Math.\mathrm{JE}.Math.}^2+{.Math.\mathrm{OE}.Math.}^2-{.Math.\mathrm{OJ}.Math.}^2}{2.Math..Math.\mathrm{JE}.Math..Math..Math.\mathrm{OE}.Math.}\right)$${\varphi }_2={\cos }^{-1}\left(\frac{{{.Math.\mathrm{OJ}.Math.}^2+|\mathrm{JE}.Math.}^2-{.Math.\mathrm{OE}.Math.}^2}{2.Math..Math.\mathrm{OJ}.Math..Math..Math.\mathrm{JE}.Math.}\right)$${\varphi }_3={\cos }^{-1}\left(\frac{{.Math.\mathrm{OJ}.Math.}^2+{.Math.\mathrm{OE}.Math.}^2-{.Math.\mathrm{JE}.Math.}^2}{2.Math..Math.\mathrm{OJ}.Math..Math..Math.\mathrm{OE}.Math.}\right).$

[0066] While the present disclosure has been illustrated and described with respect to a particular embodiment thereof, it should be appreciated by those of ordinary skill in the art that various modifications to this disclosure may be made without departing from the spirit and scope of the present disclosure.