Rotating drive for positioning a work tool on a machine or excavator

Description

[0001] The invention relates to a rotary drive for rotary positioning of a work device on a machine or an excavator.

[0002] From DE 10 2013 206 574 A1, a rotary drive for the rotary positioning of a work unit on an excavator is known. This rotary drive comprises a worm drive consisting of a helical worm and a meshing worm wheel. Hydraulic motors are connected to each end of the worm drive to power it. The hydraulic motors are controlled by a control circuit, with the second hydraulic motor being selectable in conjunction with the first. This allows for the control of different torques and rotational speeds without any additional manual operation.

[0003] The invention is based on the objective of proposing a rotary drive for the rotary positioning of a work device on a machine or excavator, which enables increased safety during a work process of the work device.

[0004] This task is solved by a rotary drive for the rotary positioning of a work device or an excavator, in which at least one pressure relief valve is provided between a first and a second supply line leading to the rotary drive, which opens when the pressure of the hydraulic fluid exceeds the working pressure in the hydraulic fluid pressurized supply line, and in which the worm and / or worm wheel of the worm drive are designed with a thread pitch without self-locking.

[0005] This prevents overloading of the rotary drive when operating the attachment. For example, it can happen that, with a demolition tool, the tool is tilted or offset relative to the closing movement of the shears or grapple, and excessive torque is applied to the rotary drive when the shears or grapple close. As soon as a predetermined operating pressure in the supply line is exceeded, at least one pressure relief valve can open the hydraulic supply line to release the excess pressure. Simultaneously, the worm drive with its non-locking thread pitch allows the tool to rotate relative to the excavator arm, thus aligning it with the target object.This not only prevents overloading of the rotary drive, but also, for example, a potential tipping movement of the machine or excavator. The work process can then be continued immediately with the working tool in the aligned working or gripping position.

[0006] Furthermore, it is preferably provided that at least one short-circuit line is provided between the first and second supply lines, and that at least one pressure relief valve is arranged in the at least one short-circuit line. This allows for a compact design of the control circuit.

[0007] Advantageously, a first and a second pressure relief valve are provided between the first and second supply lines, particularly in a bypass line. The pressure relief valves are oriented in opposite directions to open in the event of a pressure increase in the hydraulic fluid. This ensures that both a rotary movement of the actuator to the left or right is controlled and that a pressure increase is prevented.

[0008] At least one pressure relief valve has an adjustable or controllable opening pressure. This allows different load cases to be predefined. It also makes this rotary actuator and its control circuit universally applicable to light or heavy-duty work processes, machines, or excavators.

[0009] Advantageously, the first and second pressure relief valves are set to the same opening pressure. This ensures consistent operating conditions regardless of the controlled rotary motion of the rotary actuator.

[0010] The pressure relief valves are advantageously designed for an opening pressure between 10 and 600 bar, in particular between 40 and 380 bar.

[0011] According to a first embodiment, the opening pressure of the at least one pressure relief valve can be electrically adjustable. Alternatively, it can also be controlled in steps or continuously. Advantageously, the operator of the machine or excavator can control this from their working position.

[0012] To support the rotary motion of the worm gear relative to the worm, which has a non-self-locking thread pitch, lubrication of the worm drive is preferably provided. Such lubrication allows for the adjustment of a defined frictional resistance between the worm gear and the worm, which in turn, together with the adjustable opening pressure of the pressure relief valve, allows for the creation of defined operating conditions. Advantageously, a lubrication interface is provided on a housing of the worm gear or a housing of the rotary drive to supply lubricant, such as oil or grease, particularly during maintenance intervals.

[0013] The control circuit advantageously includes a 4 / 2-way valve. This allows for simple control of a left or right rotation of the rotary actuator, as well as a neutral position without pressurizing either of the two supply lines.

[0014] Furthermore, it is preferably provided that at least one pressure relief valve is positioned in the housing of the rotary actuator or close to the housing of the rotary actuator on the consumer side, between the changeover valve and the hydraulic motor. This arrangement has the advantage that short paths from the worm gear, via the worm and the hydraulic motor, to the pressure relief valve are ensured in the event of a pressure surge, so that the pressure relief valve responds immediately in the event of a pressure surge and the resulting load peak can be absorbed. Positioning the pressure relief valve close to the hydraulic motor allows for high sensitivity. This can provide increased safety, in particular with regard to preventing the machine or excavator from rotating or tilting towards the object being gripped.

[0015] Furthermore, it is preferably provided that the control circuit has at least one secondary valve on the working side between the changeover valve and the rotary actuator, which is designed to protect against an absolute overload of the working pressure in the supply lines. This at least one secondary valve acts as a safeguard against an absolute overload of the working pressure in the hydraulic actuator. This at least one secondary valve is preferably located remotely from the rotary actuator or the hydraulic motor and their associated pressure relief valves, so that this at least one secondary valve enables a rapid response safety function of the control circuit before the overload occurs at the hydraulic motor.

[0016] The adjustable opening pressure of the at least one pressure relief valve is preferably lower than the opening pressure of the absolute overload of the at least one secondary valve.

[0017] The invention, as well as further advantageous embodiments and developments thereof, are described and explained in more detail below with reference to the examples shown in the drawings. The features that can be derived from the description and the drawings can be applied individually or in any combination according to the invention. The drawings show: Figure 1 is a schematic side view of an excavator with a work attachment; Figure 2 is a perspective view of an attachment device for tying to a stick of the excavator according to Figure 1; Figure 3 is a schematic side view of the attachment device according to Figure 1. Figure 2 Figure 4 shows a schematic view of a control circuit for a rotary drive of the attachment device according to Figure 2 Figure 5 shows a schematic sectional view of the rotary drive with a worm drive.

[0018] In Figure 1Figure 11 is a schematic side view of an excavator 11. The excavator 11 comprises a base machine 13 with a boom 12, which is articulated at its end to a stick 14. The boom 12 is moved up and down by a lifting cylinder 19. The boom 12 includes at least one stick cylinder 18 for controlling a pivoting movement of the stick 14. At least one pressure cylinder 16 is provided on the stick 14, by which an attachment 21 provided on the stick 14 can be controlled. The attachment 21 is pivotably mounted at the end of the stick 14 in an attachment axis 17. This attachment 21 can include a rotary device 22 with a rotary drive 24 and a coupling, in particular a quick-change device 23. The rotary device 22 includes a drive housing 66. The rotary drive 24 allows the quick-change device 23 to rotate relative to the drive housing 66 in a rotation axis 26.A tool 25 is provided interchangeably on the quick-change device 23. The quick-change device 23 has a first changer half 41, which is located on the tool side, and a second changer half 42, which is located on the rotary drive 24. The second changer half 42 comprises at least one controllable locking bolt 56. After a locking bolt receptacle 59 is positioned on the first locking bolt 55 of the first changer half 41, the locking bolt 56 can engage behind the second locking bolt 55 of the first changer half 41 and connect and lock the first and second changer halves 41, 42. Such a quick-change device is known, for example, from DE 20 2021 101 016 U1.

[0019] A swivel kinematic mechanism 27 is provided to control a swivel movement of the attachment 21. This mechanism comprises a deflection 28, which is pivotally connected at one end to the stem 14 via a deflection axis 29. The swivel kinematic mechanism 27 also includes a coupling 31, which is connected at one end to the deflection 28 via a common swivel axis 35. At the opposite end, the coupling 31 engages a coupling device 33. This coupling device 33 is a component of the attachment 21 or is mounted on the attachment 21. Preferably, the drive housing 66 has a cover surface extending at least partially, on which the coupling device 33 is provided. The pressure cylinder 16, in particular a piston rod of the pressure cylinder 16, engages the swivel axis 35 of the swivel kinematic mechanism 27.

[0020] In Figure 2 A perspective view of the attachment device 21 is shown. Figure 3shows a schematic side view of this attachment device 21 according to Figure 2 .

[0021] The coupling device 33 consists of two cheeks 36 arranged at a distance from each other. The cheeks 36 can be connected to at least one connecting plate 34 extending between the cheeks 36. The at least one connecting plate 34 can abut a top surface of the rotary device 22 and is preferably detachably attached thereto. Each cheek 36 comprises a coupling bearing point 37 and a mounting bearing point 38. The coupling bearing point 37 and the mounting bearing point 38 are arranged offset from each other vertically. The mounting bearing point 38 is recessed relative to the coupling bearing point 37. The mounting bearing point 38 can also be offset towards a plane of rotation 39 of the rotary device 22 or lie within this plane of rotation 39. The mounting bearing point 38 is laterally offset outwards relative to the mounting device 21, in particular the rotary device 22, or is associated with an end face of the rotary device 22.

[0022] The rotary device 22 further comprises a rotary feedthrough 71, through which hydraulic lines can be routed through the rotary device 22 to be coupled with a working device 25. This allows, for example, the control of a shear, a gripper, or another drive such as a vibratory drive or the like.

[0023] In Figure 4A schematic diagram shows a control circuit 44 of the rotary drive 24 for controlling a rotary movement of the rotary device 22 or the working tool 25. A worm drive 46 is provided in a housing 45 of the rotary drive 24. This comprises a worm 47 which meshes with a worm gear 48. A hydraulic motor 49 is connected to one end of the worm 27. The hydraulic motor can be, for example, an axial piston motor, a radial piston motor, or a gear pump motor. This hydraulic motor 49 is controlled via a first supply line 51 and a second supply line 52. These supply lines 51 and 52 are connected to a changeover valve 53. This changeover valve 53 is preferably a 4 / 2-way valve.

[0024] The changeover valve 53 is connected to a tank 57 via a hydraulic line 68. Hydraulic fluid is supplied from the tank 57 to the changeover valve 53 via a pump 54 and the hydraulic line 68. A hydraulic line 69 is also connected to the changeover valve 53, which serves as a return line and leads into a tank 57.

[0025] The control circuit 44 has a drive-side section extending between the tank 57 and the changeover valve 53. The control circuit 44 has a working-side section extending between the hydraulic motor 49 and the changeover valve 53.

[0026] Depending on the switching position of the changeover valve 53, the first supply line 51 can be pressurized with hydraulic fluid. In this case, a rotary movement of the rotary actuator 24 in a first direction of rotation, for example, clockwise rotation, is initiated. The second supply line 52 serves to return the working fluid to the tank 57. After switching the changeover valve 53, the supply line 52 can be switched to pressurized with hydraulic fluid, so that the second supply line 52 is pressurized and the hydraulic motor 49 is driven in a second direction of rotation, for example, counterclockwise rotation. Thus, both the first supply line 51 and the second supply line 52 can form an inlet to or outlet from the hydraulic motor 49.

[0027] At least one pressure relief valve 61, 62 is provided between the first and second supply lines 51, 52. For example, a first bypass line 63 is provided with a first pressure relief valve 61 and a second bypass line 64 with a second pressure relief valve 62. The first and second pressure relief valves 61, 62 are designed to act in opposite directions in the event of a pressure increase in the hydraulic fluid. Thus, in the event of an increase in the working pressure in supply line 51 as well as in the supply line 52, the pressure relief valves 61, 62 can open quickly to prevent a pressure increase on the rotary actuator 24.

[0028] In the working area of ​​the control circuit 44, at least one secondary valve 60 is provided. This secondary valve 60 is directly associated with the changeover valve 53. Preferably, the changeover valve 53 and the secondary valve 60 are positioned in the upper structure of the excavator 11. Preferably, each supply line 51, 52 is connected to a secondary valve 60. This secondary valve 60 serves to prevent an absolute overload of the working pressure in the supply lines 51, 52. In the event of an absolute overload, the hydraulic fluid is immediately returned to the tank 57 and the pressure is reduced before it is applied to the hydraulic motor 49. The pressure relief valve 61, 62 can be provided on the attachment 21, preferably within the housing 45 of the rotary actuator 24. This pressure relief valve 61, 62 can also be provided near the rotary actuator 24.The positioning can also be provided on a stem 14 adjacent to the coupling device 33. The spatial proximity of at least one pressure relief valve 61, 62 to the hydraulic motor 49 ensures that load peaks can be quickly reduced, thus providing increased overload protection.

[0029] In Figure 5 A schematic sectional view of the rotary drive 24 is shown. The worm 47 is supported at its respective ends. The hydraulic motor 49 is attached to one end of the worm 47. The worm 47 drives the worm wheel 48, whose axis of rotation lies in the axis of rotation 26 of the rotary device 22.

[0030] The rotary actuator 24 described above, with its control circuit 44, exhibits increased sensitivity to load-side or load-side overloads. The pressure relief valves 61 and 62, which control the hydraulic motor 49 in the event of an overload on the actuator side, have an adjustment range below or near the absolute overload threshold at which at least one secondary valve 60 opens. This enhances operational safety. This is illustrated by the following example application:

[0031] The working device 25 is designed, for example, as a pair of shears, in particular demolition shears. An open pair of shears is positioned in a tilted or twisted orientation relative to the object being gripped. Subsequently, a closing movement of the shears is initiated, whereby, for example, due to the tilted position, the shears cannot cut the object being gripped. However, this would result in a pressure increase in the control circuit 44, particularly on the consumer side, due to the pressure build-up via the pump 54. This could cause the entire machine or excavator 11 to tip over towards the object being gripped.The control circuit 44, however, enables one of the two pressure relief valves 61, 62 to open on the consumer side if the pressure exceeds a preset working pressure, which is preferably below the absolute overload. This prevents the hydraulic motor 49 from receiving any further hydraulic fluid to control a rotary movement. Due to the design of the worm drive 46 without self-locking, the shears can align themselves with the object being gripped. The machine or excavator 11 remains stationary without rotating towards the object. The closing movement of the shears or the attachment can then be controlled to continue the work process.

Claims

1. Rotary drive for rotationally positioning a work device (25) on a machine or an excavator (11), - comprising a worm drive (46) that includes a helical worm (47) and a worm wheel (48) meshing therewith, - with a hydraulic drive (50) comprising at least one hydraulic motor (49) and a control circuit (44) connected thereto, - wherein the hydraulic motor (49) engages one end of the worm (47), - wherein the control circuit (44) comprises a switching valve (53) that controls a first and second supply line (51, 52) leading to the at least one hydraulic motor (49), , wherein, to drive the rotary drive (24) in a first direction of rotation, the first supply line (51) is supplied with hydraulic fluid, and to drive the rotary drive (24) in a second direction of rotation, the second supply line (52) is supplied with hydraulic fluid, characterized in - that at least one pressure relief valve (61, 62) is provided between the first and second supply lines (51, 52), which opens in the event of an increase in the working pressure of the hydraulic fluid in the supply line (51, 52) pressurized with hydraulic fluid, and - that the worm (47) and / or the worm wheel (48) are designed with a thread pitch without self-locking.

2. Rotary drive according to claim 1, characterized in that at least one bypass line (63, 64) is provided between the first and second supply lines (51, 52), and the at least one pressure relief valve (61, 62) is provided in the at least one bypass line (63, 64).

3. Rotary drive according to claim 1 or 2, characterized in that a first pressure relief valve (61) and a second pressure relief valve (62) are connected between the first and second supply lines (51, 52), which open in opposite directions in the event of an excess pressure of the hydraulic fluid in the supply lines (51, 52).

4. Rotary drive according to one of the preceding claims, characterized in that an opening pressure of the at least one pressure relief valve (61, 62) is adjustable or controllable.

5. Rotary drive according to one of the preceding claims, characterized in that the first and second pressure relief valves (61, 62) are adjustable to the same opening pressure.

6. Rotary drive according to one of the preceding claims, characterized in that the at least one pressure relief valve (61, 62) is adjustable to an opening pressure between 10 bar and 600 bar.

7. Rotary drive according to one of the preceding claims, characterized in that the opening pressure of the at least one pressure relief valve (61, 62) is electrically adjustable or can be switched in steps or continuously.

8. Rotary drive according to one of the preceding claims, characterized in that the worm drive (46) is provided with lubrication.

9. Rotary drive according to claim 8, characterized in that a lubricant can be supplied from the outside into a housing (45) of the worm drive (46) through a lubricant interface.

10. Rotary drive according to one of the preceding claims, characterized in that the changeover valve (53) is designed as a 4 / 2-way valve.

11. Rotary drive according to one of the preceding claims, characterized in that the at least one pressure relief valve (61, 62) is positioned in the housing (45) of the rotary drive (24) or near the housing (45) of the rotary drive (24) on the consumer side between the changeover valve (53) and the hydraulic motor (49).

12. Rotary drive according to any one of the preceding claims, characterized in that the control circuit (44) comprises, on the working side between the changeover valve (53) and the rotary drive (24), at least one secondary valve (60), which is provided to ensure a, preferably adjustable, absolute overload of a working pressure in the supply lines (51, 52) and opens when the absolute overload is reached.

13. Rotary drive according to one of the preceding claims, characterized in that the adjustable opening pressure of the at least one pressure relief valve (61, 62) is lower than the opening pressure of the absolute overload of the at least one secondary valve (60).