AUTOMATIC TOOL TILT COMMAND SYSTEM

Abstract

Automatic tilt command system of a hydraulically driven boom moveably connected with one end to a chassis of a working machine, wherein a tiltable tool is attachable to the other end. The system further comprises a first electronic control valve for controlling a fluid flow to and from a boom lift cylinder for moving of the boom and a second electronic control valve for controlling a fluid flow to and from a tilt cylinder for tilting the tool. A control unit receives input signals with regard to moving the boom and transmits based on the received input signals actuating signals to the first electronic control valve in order to move the boom. In parallel the control unit transmits tilting signals to the second electronic control valve which are based on a predetermined fluid flow ratio defined by the fluid flow for the boom movement and the fluid flow for tool levelling, so that the tool maintains its inclination angle with respect to the horizontal.

Claims

1. Automatic tilt command system of a hydraulically driven boom moveably connected with one end to a chassis of a working machine, wherein a tiltable tool is attachable to the other end, the system further comprising: a first electronic control valve for controlling a fluid flow to and from a boom lift cylinder for moving of the boom; a second electronic control valve for controlling a fluid flow to and from a tilt cylinder for tilting the tool; and a control unit for receiving input signals with regard to moving the boom, which control unit transmits based on the received input signals actuating signals to the first electronic control valve in order to move the boom, and transmits in parallel corresponding tilting signals to the second electronic control valve, which are based on a predetermined fluid flow ratio defined by the fluid flow for the boom movement and the fluid flow for tool levelling, so that the tool maintains its inclination angle with respect to the horizontal.

2. System according to claim 1, wherein the input signals are transmitted via a joystick command by an operator.

3. System according to claim 1, wherein the first electronic control valve and the second electronic control valve can be actuated by means of solenoids receiving the actuating signals or the levelling signals, respectively.

4. System according to claim 1, wherein the input signals, the actuation signals, and/or the levelling signals to and/or from the control unit are transmitted by wire and/or wirelessly and/or by a bus system.

5. System according to claim 1, wherein the spools of the first electronic control valve and the second electronic control valve are pressure compensated and/or centred in the initial position by valve springs.

6. System according to claim 1, wherein an electronic load sharing unit ensures that there is always sufficient fluid flow through both the first electronic control valve and the second electronic control valve, so that the predetermined fluid flow ratio is always maintained, when moving the boom.

7. System according to claim 1, wherein the boom comprises at least two boom elements which are movable relative to each other by means of at least one relative movement cylinder, wherein a fluid flow to and from the at least one relative movement cylinder is controlled by at least one additional electronic control valve.

8. System according to claim 7, wherein the boom is configured for telescopic extension and retraction and the at least one relative movement cylinder extends and retracts the telescopic boom.

9. System according to claim 1, wherein the inclination angle of the tool can be adjusted via a joystick command by an operator independent to the commands for moving the boom.

10. System according to claim 1, wherein the tool is a fork of a telehandler, or a shovel, a grapple, a breaker of an excavator, or an auger of a drilling machine, or the like.

11. Working machine comprising: a hydraulically driven boom moveably connected with one end to a chassis of the working machine, and with a tiltable tool attached at the other end, and an automatic tool tilt control system according to claim 1, wherein a hydraulic system for providing the lift cylinder via the first electronic control valve and for providing the tilt cylinder via the second electronic control valve with hydraulic fluid flow is controlled by an electronic load sharing unit for ensuring sufficient fluid flow to both the lift cylinder and the tilt cylinder so that a predetermined fluid flow ratio defined by the fluid flow for the boom movement and the fluid flow for tool levelling can be met and so that the tool maintains its inclination angle with respect to the horizontal during boom movement.

12. Working machine according to claim 11, wherein the tool can be attached to and detached from the boom by means of a hydraulic quick coupling unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1 is a schematic view of a first embodiment of an automatic tilt command system according to the invention; and

[0021] FIG. 2 is a schematic view of a second embodiment of an automatic tilt command system according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Referring to the Figures, in a preferred embodiment an automatic tilt command system 10 is used with a telehandler having a chassis 12. Moveably connected to the chassis 12 is a boom 14 and moveably connected to the boom 14 is a tool 16, e.g. a fork 16. Connected to and extending between the chassis 12 and the boom 14 is a boom lift cylinder 18, for lifting or lowering the boom 14. Connected to and extending between the boom 14 and the tool 16 is a tool tilt cylinder 20 for setting/adjusting the inclination of the tool 16 with respect to the horizontal direction, when the boom is lifted or lowered.

[0023] The system further includes a hydraulic system 24, a control unit 26, and a first electronic control valve 28 and a second electronic control valve 30, which are preferably pressure compensated valves. The first electronic control valve 28 controls the flow of hydraulic fluid between the hydraulic system 24 and the lift cylinder 18, while the second electronic valve 30 controls the flow of fluid between the hydraulic system 24 and the tilt cylinder 20.

[0024] In operation, an input command for moving the boom 14 is sent to the controller 26 from an operator using a joystick or the like via an input signal line 25. The controller 26 calculates flow requirements for the lift cylinder 18 and the tilt cylinder 20 based upon the input command and a predetermined flow ratio necessary to fulfill the required boom movement and to keep the inclination of the tool with regard to the horizontal direction. For doing this, based upon the calculated flow requirements, boom actuating signals are sent from the controller 26 to the first electronic control valve 28 via an actuating signal line 27 and in parallel tool tilting signals are sent to the second electronic control valve 30 via a levelling signal line 29.

[0025] Based upon these signals, each electronic control valve 28 and 30 permits the calculated amount of fluid to flow between the hydraulic system 24 and the lift and tilt cylinders 18 and 20 which causes the boom 14 to be raised or lowered while the tool 16 is maintained in its inclination.

[0026] In a further preferred embodiment the actuating signal transmitted by the control unit 26 via actuating signal line 27 is received by a lift actuator 34 for actuating the first electronic control valve 28 to fulfil the lift requirement according to the input command signal to the control unit 26. In parallel to the transmitted actuation signal via the levelling signal line 29 a tilt signal is transmitted by the control unit 26 to a levelling actuator 36 for actuating the second electronic control valve 30 in order to maintain the inclination of the tool 16 with respect to the horizontal as it was before the input command signal was sent to the control unit 26. So, the control unit 26 generates a second, parallel tilt signal to compensate the change in the angle of tilt which would occur when the boom is raised or lowered without such compensation. For such a compensation the prior art uses compensation cylinders or sensors which feed back a change of tilt angle, which have to be corrected in order to prevent falling down of the load from the tool 16.

[0027] According to the invention the operator is still able to make adjustments to the tool tilt function, e.g. via a tool tilt input line 45. This is shown with the embodiment of FIG. 2. Hence an operator is still able to set the inclination of the tool 16 manually according to operational requirements for the working machine or to correct based on visual observation the inclination angle of the tool 16. To this effect, the inventive automatic tilt command system is an open loop control system.

[0028] In the embodiment of FIG. 2 the inventive automatic tilt command system is influenced/controlled by an electronic load sharing system 40 which automatically adapts the input command for moving the boom to current ability of the hydraulic system 24 such that the total commanded pump flow of the working machine does not exceed the capacity of the hydraulic system. This adaptation is based, e.g., on pump speed, which usually depends on the engine speed, and is controlled to provide maximum overall efficiency of the working machine. Hence, electronic load sharing makes it possible to always have sufficient flow so that the predetermined flow ratio for tool tilt compensation is always maintained. However the electronic load sharing system controls, e.g., the speed with which the movement of the boom with correspondent tilt compensation is performed. The ability for the operator to make adjustments to the tilt function via joystick will still be functional. Also, if the predetermined ratio of the boom movement flow to the tilt flow is not constant for all positions of boom movement, neither compensation cylinders nor position sensors or angle sensors will be necessary for automatic tool leveling, as operator corrections of the tilt angle are always possible, e.g. based on visual control of the operator.

[0029] In another embodiment of the invention, which is not shown in the Figures, the automatic tilt system 10 can be applied also to telescopic booms having more than one boom element 15 forming the moveable boom 14. In such an embodiment the boom 14 can be raised or lowered by the boom lift cylinder 18 and can be retracted or extended in its longitudinal direction, e.g., by a relative movement cylinder 22 moving the boom elements 15 relative to each other. In this case according to the invention an additional electronic control valve 32 is controlled by the control unit 26 as well such that both cylinders for moving the boom are considered by the predetermined flow ratio, which is defined by the total flow fluid required for boom movement and the fluid flow necessary for tilt angle compensation.

[0030] The inventive automatic tilt command system is also applicable with working machines showing foldable booms in an analogous way, as the fluid flow necessary for the boom movement, respectively, the relative movements of the boom elements 15, driven by two or more boom movement cylinders 18 and 22 form together a total fluid flow which is the base for determining the predetermined flow ratio in order to compensate the tilt angle change of the tool with respect to the boom in order to keep the absolute inclination with respect to the horizontal direction stable, e.g. levelled.

[0031] From the above discussion and accompanying figures and claims it will be appreciated that the automatic tilt command system 10 offers many advantages over the prior art. It will be appreciated further by those skilled in the art that other various modifications could be made to the device without parting from the spirit and scope of this invention. All such modifications and changes fall within the scope of the claims and are intended to be covered thereby. It should be understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in the light thereof will be suggested to persons skilled in the art and are to be included in the spirit and purview of this application.