Locking control method of pivot axle, pivot axle locking controller and pivot axle locking system

Abstract

The present application relates to a locking control method of a pivot axle, a pivot axle locking controller and a pivot axle locking system, in particular a locking control method of a pivot axle for a wheeled work machine, comprising the steps of: determining a current attitude and motion state of the work machine and static and dynamic forces acting on the work machine, a multi-body simulation model is preferably used for determination; determining an associated tip-over line based on a current locked state of a pivot axle of the work machine; calculating a torque acting on the work machine based on information about the current attitude, the motion state, the static force, and the dynamic force; a control command for a pivot axle lock mechanism of the work machine is determined based on the calculated torque and the tip-over line and provided to the pivot axle lock mechanism.

Description

Technical Field

[0001] The present invention relates to a locking control method for a pivoting wheel axle of a wheeled working machine, a pivoting wheel axle locking controller and a pivoting wheel axle locking system for the working machine.

[0002] The invention can be applied to wheeled working machines such as excavators, telescopic forklifts, off-road cranes or wheel loaders with pivoting axles or tractors or combine harvesters. Although the invention will be described primarily with respect to excavators, the invention is not limited to this particular vehicle but can also be used for other wheeled vehicles such as telescopic forklifts, off-road cranes or wheel loaders with pivoting axles or tractors or combine harvesters. Background Art

[0003] The purpose of the pivoting axle at a wheeled work machine is to allow the front axle to rotate up to an angle of, for example, 9° to improve traction in uneven terrain. Sometimes, a hydraulic locking mechanism allows the rotation of the axle to be locked so that the axle behaves as a rigidly mounted axle, for example for lifting operations or when digging. Due to the change in the tipping line, the tipping stability of the machine varies greatly between the unlocked and locked states of the pivoting axle. Although in today's applications, the pivoting axle is automatically closed when the machine is not traveling, when the operator is driving the machine and it is expected that he will need more lateral stability (for example, because he is swinging a heavy load or tool attached to the machine on the side of the machine), he must manually close the axle by pressing a button on the joystick. Alternatively, he can choose to always close the axle via a switch in the console.

[0004] EP 2 444 304 B1 describes a method for preventing a vehicle from tipping over by locking the front axle. Therein, the use of the pitch angle and the roll angle is described as a comparison with threshold values ​​of these angles as an intervention initialisation. Thus, intervention is not carried out until the threshold value is reached. Existing solutions therefore mainly consist of automatically locking the pivoting axle when the machine is not moving and the automatic excavation brake is engaged or when a certain rotation angle of the superstructure is exceeded. Summary of the invention

[0005] It is an object of the present invention to provide an improved locking control which allows automatic closing of the pivoting axle in a safe manner based on the current situation.

[0006] According to a first aspect of the present invention, the object is achieved by a locking control method as described below. The locking control method for a pivoting wheel axle of a wheeled working machine comprises the following steps:

[0007] - determining the current posture and motion state of the work machine and the static and dynamic forces acting on the work machine, preferably using a multibody simulation model to determine the current posture and motion state of the work machine and the static and dynamic forces acting on the work machine;

[0008] - determining the relevant tipping line based on the current locking state of the pivoting axle of the work machine;

[0009] - Calculate the torque acting on the work machine based on information about the current posture, state of motion, static forces and dynamic forces;

[0010] - determining a control command for a pivoting axle locking mechanism of the work machine based on the calculated torque and the tipping line;

[0011] - Provide the control command to the pivoting axle locking mechanism.

[0012] The present invention is based on the recognition that by calculating the torque acting on the working machine and determining the control command based on the calculated torque, earlier intervention or warning is possible because when the acting straight line of the resultant of all forces acting on the machine approaches the limit of the tipping line from the safe side (inside), intervention may have already occurred and an unsafe situation avoided.

[0013] Furthermore, the invention also comprises the recognition that by calculating the torques and using them for the control signal, the invention allows controlling the pivoting axle locking in an open control loop without any feedback loop, since the pivoting axle does not need to be monitored. Thus, control is achieved without any control deviation or error signal. This is important, for example, in the case of an undamped pivoting axle of an excavator, since the machine quickly tips over when the line of action of the resultant of all forces acting on the machine crosses the limits of the stationary polygon.

[0014] The invention further improves the travel and operation of wheeled work machines by allowing the locked / unlocked state of the pivoting axle to be automatically controlled in all situations based on the static and dynamic stability of the machine. This includes situations such as object handling in uneven terrain where simultaneous travel and load positioning (e.g. swinging on the side of the machine while traveling), roadside hedge trimming with a heavy tool such as a lawn mower, ditch cleaning (the machine is driven along a ditch in generally uneven terrain with the superstructure rotated 90° to the side and an additional bucket arm attached with a mowing bucket or other tool for a wider range), sudden turns when traveling quickly with the pivoting axle unlocked. The pivoting axle can then be automatically closed due to dynamic instabilities and all four wheels remain on the ground to provide traction, while the inner rear wheel will be lifted off the ground by the open pivoting axle.

[0015] The automatic locking and unlocking of the pivoting axle further assists the operator by automatically locking and unlocking the pivoting axle, allowing him to concentrate on other things. In addition, the invention allows the locking and unlocking of the pivoting axle in all situations also for autonomous wheeled working machines. In summary, the invention allows early and rapid intervention and therefore safe operation in a wide range of situations and applications.

[0016] According to one embodiment of the locking control method, determining the current posture and motion state of the working machine and the static and dynamic forces includes: measuring the swing angle and orientation of the attached parts of the working machine and calculating the total center of gravity. This embodiment is particularly useful in applications with slow mechanical movement, such as slow travel, slow swing speed and / or slow movement of accessories. For this embodiment, a multi-body simulation model will not be required. Instead, the position of the total center of gravity of the machine can be obtained from the gravity of each mass block and the current position of their center of gravity. The total center of gravity can then be referenced with reference to the current tipping line to evaluate the torque acting on the machine and determine the control command taking into account the total center of gravity and the current tipping line.

[0017] According to another embodiment, determining the current posture and motion state of the working machine as well as the static and dynamic forces includes: measuring the vehicle acceleration and / or the angular acceleration of the upper bracket and / or the attached parts of the working machine, the vehicle speed and / or the angular velocity of the upper bracket and the attached parts, the orientation of the attached parts, the swing angle and the brake pressure, and providing these measured values ​​to the multi-body simulation model, wherein preferably, the angular acceleration, the angular velocity and the orientation are measured via at least one inertial measurement unit. The above-mentioned additional sensor data, such as the angular velocity and angular acceleration and the swing angle of the attached parts, as well as the vehicle speed and the brake pressure, allow the functionality of the system to be extended to dynamic motion. In this embodiment, it is advantageous to use multi-body simulation.

[0018] According to another embodiment, determining the current attitude and state of motion of the working machine comprises: additionally measuring the pressure in the boom cylinder to determine the attached load. This allows also considering the effect of the load on the static and dynamic forces. According to another embodiment, determining the control command comprises: balancing the calculated torque around the relevant tipping line.

[0019] According to another embodiment, hysteresis is applied before providing the control command to the pivoting axle locking mechanism, or wherein a hysteresis signal is provided to the pivoting axle locking mechanism. Although the method works without hysteresis, hysteresis is a technical measure to improve usability by avoiding frequent locking and unlocking when the center of gravity of the machine oscillates around the tipping line.

[0020] According to a second aspect of the invention, the object is achieved by a pivoting axle locking controller. The pivoting axle locking controller is configured to perform the steps of the locking control method according to the first aspect of the invention. Preferably, the locking controller is part of an ECU of the machine.

[0021] According to a third aspect of the present invention, the object is achieved by a computer program comprising program code components for executing the steps of the locking control method according to the first aspect of the present invention when the program is run on a computer.

[0022] According to a fourth aspect of the present invention, the object is achieved by a computer readable medium. The computer readable medium carrying a computer program includes a program code component for executing the steps of the locking control method according to the first aspect of the present invention when the program product is run on a computer.

[0023] According to a fifth aspect of the present invention, the object is achieved by a pivoting axle locking system. The pivoting axle locking system comprises:

[0024] - a pivoting axle locking mechanism, preferably comprising a hydraulic locking valve (2), and

[0025] - A pivoting axle locking controller according to the second aspect of the invention.

[0026] According to one embodiment, the pivoting wheel axle locking system also includes at least one inertial measurement unit and a swing angle sensor connected to the pivoting wheel axle locking controller. These sensors preferably measure the vehicle acceleration and / or the angular acceleration of the upper bracket and / or the attachment part of the working machine, the vehicle speed and / or the angular velocity of the upper bracket and the attachment part, the orientation and the swing angle of the attachment part. For vehicles without moving parts such as booms but with pivoting wheel axles (for example, tractors or combine harvesters), only one inertial measurement unit on the body is sufficient. For vehicles such as telescopic forklifts that do not necessarily have a rotating upper bracket, a body inertial measurement unit, an inertial measurement unit on the boom and a pressure sensor on the boom cylinder will be sufficient to calculate the COG of the machine. With this information, when the machine is operating on a steep slope, the rollover stability of the machine can be increased by locking the pivoting wheel axle. For wheeled working machines with moving parts and a rotating upper bracket, several inertial measurement units on the body, the dipper and the attachment part are preferred.

[0027] According to another embodiment, the pivot axle locking system further comprises a pressure sensor in a boom cylinder of the work machine.

[0028] Preferably, the hydraulic locking valve is a solenoid valve. Further preferably, the pivoting wheel axle locking system further comprises a proportional throttle valve. This improves operator comfort when switching between the locked state and the unlocked state of the pivoting wheel axle.

[0029] According to a sixth aspect of the present invention, the object is achieved by a wheeled working machine comprising a pivoting wheel axle locking system according to the fifth aspect of the present invention.

[0030] With regard to advantages, preferred embodiments and details of the pivoting wheel axle locking controller, computer program, computer readable medium, pivoting wheel axle locking system and wheeled working machine, reference is made to the corresponding aspects and embodiments described above with regard to the locking control method.

[0031] Further advantages and advantageous features of the invention are disclosed in the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] With reference to the accompanying drawings, below follows a more detailed description of embodiments of the invention cited as examples.

[0033] In these figures:

[0034] Figure 1 is a schematic diagram of a wheeled working machine according to a sixth aspect of the present invention, showing a tipping line of the wheeled working machine,

[0035] Figure 2a is a schematic diagram of a tractor according to a sixth aspect of the present invention,

[0036] Figure 2b It is shown Figure 2a Schematic diagram of the tipping line of the tractor,

[0037] Figure 3 is a schematic diagram of another wheeled working machine according to a sixth aspect of the present invention,

[0038] Figure 4 is a schematic diagram of a pivoting axle locking system according to a fifth aspect of the present invention, and

[0039] Figure 5 is a schematic diagram of a locking control method according to the first aspect of the present invention. DETAILED DESCRIPTION

[0040] It should be understood that the present invention is not limited to the embodiments described above and shown in the drawings; on the contrary, those skilled in the art will recognize that many modifications and variations are possible within the scope of the appended claims.

[0041] Throughout the specification, the same reference numerals refer to the same elements.

[0042] Figure 1 1 is a schematic diagram of a wheeled work machine 1000 according to a sixth aspect of the present invention, showing the rollover line of the wheeled work machine. The work machine 1000 has four wheels 100 and a mechanical main body 200. The two rear wheels are connected via a rigid rear axle, and the front wheels are connected via a pivoting axle. The pivot joint PJ of the pivoting axle is centrally arranged. The front rollover line FTL and the rear rollover line RTL extend along the corresponding axles. Due to the change of the rollover line, the rollover stability of the machine is greatly different between the unlocked state and the locked state of the pivoting axle. If the pivoting axle is locked and thus behaves like a rigid axle, the left rollover line STLL (B) is a straight line between the center of the left front wheel and the center of the left rear wheel. Then, the right rollover line STLR (B) is a straight line between the center of the right front wheel and the center of the right rear wheel. By unlocking the pivoting axle, the left rollover line and the right rollover line change fundamentally. Then, the right side rollover line STLR(A) and the left side rollover line STLL(A) are straight lines between the pivot joint PJ and the center of the corresponding right rear wheel or left rear wheel. In order to avoid rollover, the center of gravity must be placed between the corresponding rollover lines in this case. The locking control method for the pivoting axle of a wheeled working machine ensures that: when the center of gravity reaches the rollover line in the unlocked state of the pivoting axle, the pivoting axle is locked to enhance stability, and on the other hand, if the center of gravity is between the right side rollover line STLR(A) and the left side rollover line STLL(A), the pivoting axle is unlocked to enhance traction in uneven terrain.

[0043] To this end, the wheeled work machine includes a pivoting wheel axle locking system, which includes a pivoting wheel axle locking mechanism and a pivoting wheel axle locking controller, which is configured to perform the steps of a locking control method. The locking control method first includes: determining the current posture and motion state of the work machine 1000 and the static forces and dynamic forces acting on the work machine, preferably using a multi-body simulation model to determine the current posture and motion state of the work machine 1000 and the static forces and dynamic forces acting on the work machine. In addition, the relevant tipping line (STLL (A), STLR (A) or STLL (B), STLR (B)) based on the current locking state of the pivoting wheel axle of the work machine is determined. Then, the torque acting on the work machine based on the information about the current posture, motion state, static force and dynamic force is calculated, and a control command for the pivoting wheel axle locking mechanism of the work machine based on the calculated torque and tipping line is determined, and then the control command is provided to the pivoting wheel axle locking mechanism. In this context, determining the current attitude and motion state of the work machine as well as the static and dynamic forces comprises: measuring the vehicle acceleration and / or the angular acceleration of the upper support and / or the attachment of the work machine, the vehicle speed and / or the angular velocity of the upper support and the attachment, the orientation of the attachment, the swing angle and the brake pressure, and providing these measured values ​​to the multi-body simulation model, wherein the angular acceleration, the angular velocity and the orientation are measured via at least one inertial measurement unit. Figure 4 A more detailed description is given of the pivot lock control mechanism.

[0044] Figure 2a is a schematic diagram of a tractor 1100 according to the sixth aspect of the present invention on a steep slope. Here, the tractor 1100 is operating on a steep slope with an inclination angle α. The tractor 1100 shown has a pivoting axle 110 between its front wheels 100 and the machine body 200. The center of gravity COG is shown. For a vehicle (e.g. a tractor or a combine harvester) that does not have a substructure that is movable relative to the lower support (such as a boom) but has a pivoting axle as described herein, if the COG of the working machine crosses the rollover line due to a high inclination angle, it is sufficient to use only one inertial measurement unit on the body of the working machine to be able to lock the pivoting axle using the locking control method protected by the claimed protection. Figure 2b It shows Figure 2a Schematic diagram of the rollover line on the right side of the tractor. The center of gravity COG (α) indicates the COG of the tractor projected onto the rollover plane at the inclination angle α. Therefore, in case of relatively high inclination angles, when the tractor is operating on such a steep slope, the locking method control will automatically lock the pivoting wheel axle.

[0045] Figure 31 is a schematic diagram of a wheeled work machine 1200 according to a sixth aspect of the present invention. The wheeled work machine 1200 includes a pivoting wheel axle locking system, the pivoting wheel axle locking system including a pivoting wheel axle locking mechanism and a pivoting wheel axle locking controller, the pivoting wheel axle locking controller being configured to perform a reference Figure 1 The steps of the locking control method are described. Figure 1 In contrast, the wheeled work machine 1200 has a rotating superstructure 300, which is shown in place. As shown, the center of gravity changes as the superstructure moves. The locking control method uses a stability assessment method, which allows the locking state of the pivoting wheel axle to be controlled based on the actual static mechanical stability and dynamic mechanical stability. Here, the basis of the locking control method is a multi-body simulation model running on the ECU of the machine, which calculates the torque balance around the critical rollover line of the machine. The torque caused by all static and dynamic forces acting on the machine is added. As Figure 3 As shown, rotating the superstructure to either side may cause the COG of the machine to cross the roll line STLL (A), which is used to unlock the pivot axle. In this case, the control algorithm will detect that the COG is close to the roll line STLL (A) and automatically lock the pivot axle. If the operator turns the superstructure toward the neutral position, the algorithm will automatically unlock the pivot axle again, allowing the axle to rotate (as long as the machine stability allows it). Compared with the situation in Figure 2, here, an inertial measurement unit IMU on the superstructure (usually one IMU for each moving part (for example, on the boom, dipper and bucket and the rotating upper bracket)) is preferred, as well as a pressure sensor for load estimation in the boom cylinder of the working machine and a swing angle sensor for determining the static and dynamic forces acting.

[0046] Figure 4Schematic diagram of components of a pivoting axle locking system according to a fifth aspect of the present invention. The pivoting axle locking system comprises a pivoting axle locking mechanism and a pivoting axle locking controller (not shown), wherein the pivoting axle locking mechanism comprises a hydraulic locking valve (2). The pivoting axle locking system controls a hydraulic locking valve (2), which allows the pivoting axle (1) to be locked or unlocked via hydraulic logic. The hydraulic logic may be the same as in today's machinery. In order to improve the operator's comfort when switching between the locked state and the unlocked state of the pivoting axle, in addition to the hydraulic locking valve (2) (which is a solenoid valve in this article), an additional proportional throttle valve (3) may be required. The valve command for the locking valve is calculated by the pivoting axle locking controller by balancing the torques around the current relevant tipping line. These torques are derived from the static and dynamic forces acting on the machine in the current machine posture and motion state. All this information is provided by a multi-body simulation model, which in this article obtains IMU sensor signals, swing angle sensor signals, vehicle speed and brake pressure as inputs. To enhance comfort when switching between the locked and unlocked states, damping of the controller output signal and / or applying hysteresis to it may be useful. This also requires a proportional throttle valve.

[0047] Figure 5 is a schematic diagram of a locking control method according to a first aspect of the present invention. The control method comprises: as a first step S1, determining the current posture and motion state of the working machine and the static and dynamic forces acting on the working machine. Preferably, determining the current posture and motion state of the working machine and the static and dynamic forces comprises: measuring the vehicle acceleration and / or the angular acceleration of the upper bracket and / or the attachment component of the working machine, the vehicle speed and / or the angular velocity of the upper bracket and the attachment component, the orientation, the swing angle and the brake pressure of the attachment component, and providing these measured values ​​to the multi-body simulation model. In step S2, determining the relevant tipping line based on the current locking state of the pivoting wheel axle of the working machine. In step S3, calculating the torque acting on the working machine based on the information about the current posture, motion state, static force and dynamic force. In S4, determining the control command for the pivoting wheel axle locking mechanism of the working machine based on the calculated torque and tipping line, and in step S5, providing the control command to the pivoting wheel axle locking mechanism.

[0048] Reference numerals

[0049] 100 wheels

[0050] 110 Pivot axle

[0051] 200 Mechanical main body

[0052] 300 Rotating superstructure

[0053] 1000 Operating machinery

[0054] 1100 Tractor

[0055] 1200 Operating machinery

[0056] COG Center of Gravity

[0057] FTL forward tipping line

[0058] PJ Pivot Joint

[0059] RTL rear tilting line

[0060] FTL forward tipping line

[0061] STLR(A) Right rollover line, pivot axle unlocked

[0062] STLL (A) Left rollover line, pivot axle not locked

[0063] STLR (B) right side tipping line, pivot axle locked

[0064] STLL (B) Left rollover line, pivot axle locked

Claims

1. A locking control method for a pivoting wheel axle of a wheeled working machine (1000), comprising the following steps: Determining the current posture and motion state of the working machine (1000) and the static forces and dynamic forces acting on the working machine; determining a relevant tipping line (STLL, STLR) based on a current locking state of a pivoting axle of the work machine; calculating a torque acting on the work machine based on information about the current posture, the state of motion, the static forces, and the dynamic forces; determining a control command for a pivot axle locking mechanism of the work machine based on the calculated torque and the tipping line; as well as The control command is provided to the pivoting axle locking mechanism.

2. The locking control method according to claim 1, wherein: The current posture and motion state of the work machine (1000) and the static and dynamic forces acting on the work machine are determined using a multi-body simulation model.

3. The locking control method according to claim 1, wherein: Determining the current attitude and motion state of the work machine and the static and dynamic forces includes measuring the swing angle and orientation of the attached components of the work machine and calculating the overall center of gravity (COG).

4. The locking control method according to claim 2, wherein: Determining the current posture and motion state of the working machine as well as the static and dynamic forces includes: measuring the vehicle acceleration and / or the angular acceleration of the upper bracket and / or the attached parts of the working machine, the vehicle speed and / or the angular velocity of the upper bracket and the attached parts, the orientation of the attached parts, the swing angle and the braking pressure, and providing these measurement values ​​to the multi-body simulation model.

5. The locking control method according to claim 4, wherein: Angular acceleration, angular velocity and the orientation are measured via at least one inertial measurement unit.

6. The locking control method according to any one of claims 1 to 5, wherein: Determining the current attitude and motion state of the work machine includes additionally measuring pressure in a boom cylinder to determine the attached load.

7. The locking control method according to any one of claims 1 to 5, wherein: Determining the control command includes balancing the calculated torque about the associated rollover line.

8. The locking control method according to any one of claims 1 to 5, wherein: A hysteresis is applied before providing the control command to the pivoting axle locking mechanism, or wherein a hysteresis signal is provided to the pivoting axle locking mechanism.

9. A pivoting axle locking controller, the pivoting axle locking controller being configured to execute the steps of the locking control method according to any one of claims 1 to 8.

10. A computer-readable medium carrying a computer program, the computer program comprising program code components, the program code components being used to execute the steps of the locking control method according to any one of claims 1 to 8 when the computer program is run on a computer.

11. A pivoting axle locking system comprising: a pivoting axle locking mechanism, and The pivot axle lock controller of claim 9.

12. The pivoting axle locking system of claim 11, wherein: The pivoting axle locking mechanism comprises a hydraulic locking valve (2).

13. The pivoting axle locking system of claim 11 further comprising at least one inertial measurement unit and swing angle sensor connected to the pivoting axle locking controller.

14. The pivot axle locking system of any one of claims 11 to 13, further comprising a pressure sensor in a boom cylinder of the work machine.

15. The pivoting axle locking system of claim 12, wherein: The hydraulic locking valve is a solenoid valve.

16. The pivoting axle locking system according to any one of claims 11 to 13, further comprising a proportional throttle valve (3).

17. A wheeled working machine (1000) having a pivoting axle locking system according to any one of claims 11 to 16.

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