Rotary drive for rotationally positioning a work device on a machine or an excavator

Abstract

The invention relates to a rotary drive for rotationally positioning a work device (25) on a machine or an excavator (11), comprising a worm drive (46), a hydraulic motor (49), and a control circuit (44), wherein at least one pressure-limiting valve (61, 62) is provided between a first and a second supply line (51, 52), and the worm (47) and / or the worm gear (48) is equipped with a thread pitch without a self-locking function. (Figure 4)

Description

[0001] Rotary drive for rotating positioning of a working device on a machine or excavator

[0002] The invention relates to a rotary drive for the rotary positioning of a working device on a machine or an excavator.

[0003] DE 10 2013 206 574 A1 discloses a rotary drive for the rotary positioning of a working unit on an excavator. This rotary drive comprises a worm drive comprising a helical worm and a meshing worm wheel. Hydraulic motors are connected to each end of the worm to drive the worm of the worm drive. The hydraulic motors are controlled by a control circuit, with the second hydraulic motor being selectively connected to the first hydraulic motor. This allows different torques and rotational speeds to be controlled without any additional handling effort.

[0004] The invention is based on the object of proposing a rotary drive for the rotary positioning of a working device on a machine or an excavator, by means of which increased safety is enabled during a working process of the working device.

[0005] This object is achieved by a rotary drive for the rotary positioning of a working device or an excavator, in which at least one pressure relief valve is provided between a first and a second supply inlet leading to the rotary drive, which opens when a working pressure of the hydraulic fluid in the supply line pressurized with hydraulic fluid is increased, and in which the worm and / or worm wheel of the worm drive are designed with a thread pitch without self-locking.

[0006] This makes it possible to avoid overloading the rotary drive when working with the work tool. For example, it can happen that, with a work tool designed as a demolition tool, the demolition tool is tilted or offset relative to the closing movement of the shears or grab, and when the shears or grab closes, an excessive torque acts on the rotary drive. As soon as a predetermined working pressure is exceeded in the supply line, the at least one pressure relief valve can open the working pressure in the supply line pressurised with hydraulic fluid to relieve the excessive working pressure. At the same time, thanks to the worm drive with a thread pitch designed without self-locking, the work tool can rotate relative to an excavator boom in order to be moved into an aligned working position with the gripping object.This not only prevents excessive strain on the rotary drive, but also, for example, prevents a potential tipping movement of the machine or excavator. With the work tool in the aligned working position or gripping position, the work process can be continued immediately.

[0007] 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 enables a compact design of the control circuit.

[0008] Advantageously, a first and a second pressure relief valve are provided between the first and second supply lines, particularly in a bypass line each. The pressure relief valves are oriented to act in opposite directions in the event of an excessive pressure in the hydraulic fluid. Thus, a uniform effect can be achieved when controlling a rotary movement of the rotary actuator to the left or right, while also preventing an excessive pressure.

[0009] At least one pressure relief valve is adjustable or controllable with respect to its opening pressure. This allows different load cases to be predetermined. This also allows this rotary actuator with the control circuit to be universally used for light or heavy work processes, machines, or excavators.

[0010] 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 movement of the rotary actuator.

[0011] The pressure relief valves are advantageously designed for an opening pressure between 10 and 600 bar, in particular between 40 and 380 bar.

[0012] According to a first embodiment, the opening pressure of the at least one pressure relief valve can be electrically adjustable. Alternatively, this can also be controlled in stages or continuously. The operator of the machine or excavator can advantageously control this from their working position.

[0013] To support the rotary movement of the worm gear relative to the worm, which has a thread pitch without self-locking, lubrication of the worm drive is preferably provided. Such lubrication enables the adjustment of a defined frictional resistance between the worm gear and the worm, which in turn allows defined working conditions to be created with the adjustable opening pressure of the pressure relief valve. Advantageously, a lubricant 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.

[0014] The control circuit advantageously comprises a 4 / 2-way directional 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. Furthermore, it is preferably provided that the 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 provided in the event of excessive pressure, so that the pressure relief valve responds immediately in the event of excessive pressure and the resulting load peak can be broken. By positioning the pressure relief valve close to the hydraulic motor, high sensitivity can be achieved.This can provide increased safety, particularly in terms of preventing the machine or excavator from turning or tipping 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 drive, which is provided to protect against an absolute overload of a working pressure in the supply lines. This at least one secondary valve forms a safeguard in the event of an absolute overload of the working pressure in the hydraulic drive. This at least one secondary valve is preferably arranged remotely from the rotary drive or the hydraulic motor and the pressure relief valves associated with them, so that this at least one secondary valve enables a rapidly responding safety function of the control circuit before the overload is applied to 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 shown in the description and the drawings can be used individually or in any combination according to the invention. They show:

[0018] Figure 1 is a schematic side view of an excavator with a working device,

[0019] Figure 2 is a perspective view of an attachment device for connecting to a boom of the excavator according to Figure 1,

[0020] Figure 3 is a schematic side view of the attachment device according to Figure 2,

[0021] Figure 4 is a schematic view of a control circuit of a rotary drive of the attachment device according to Figure 2,

[0022] Figure 5 is a schematic sectional view of the rotary drive with a worm drive.

[0023] Figure 1 shows a schematic side view of an excavator 11. The excavator 11 comprises a base machine 13 with a boom 12, which is articulated at the end to a stick 14. The boom 12 is moved up and down by a lifting cylinder 19. The boom 12 comprises 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 means of which an attachment device 21 provided on the stick 14 can be controlled. At the end of the stick 14, the attachment device 21 is pivotally mounted in an attachment axis 17. This attachment device 21 can comprise a rotating device 22 with a rotary drive 24 and a coupling, in particular a quick-change device 23. The rotating device 22 comprises a drive housing 66. The rotary drive 24 enables the quick-change device 23 to rotate relative to the drive housing 66 in a rotation axis 26.A work tool 25 is provided for interchangeable use on the quick-change device 23. The quick-change device 23 has a first changer half 41, which is provided on the work tool side, and a second changer half 42, which is provided on the rotary drive 24. The second changer half 42 comprises at least one controllable latch 56. After positioning a latch receptacle 59 on the first latch bolt 55 of the first changer half 41, the latch 56 can engage behind the second latch 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.

[0024] To control a pivoting movement of the attachment device 21, a pivot kinematics system 27 is provided. This system comprises a deflector 28, which is pivotally connected to the stem 14 at one end via a deflector axis 29. The pivot kinematics system 27 further comprises a coupling 31, which is connected at one end to the deflector 28 via a common pivot axis 35. At the opposite end, the coupling 31 engages a coupling device 33. This coupling device 33 is a component of the attachment device 21 or is mounted on the attachment device 21. The drive housing 66 preferably has a cover surface extending at least in sections, on which the coupling device 33 is provided. The pressure cylinder 16, in particular a piston rod of the pressure cylinder 16, engages the pivot axis 35 of the pivot kinematics system 27.

[0025] Figure 2 shows a perspective view of the attachment device 21. Figure 3 shows a schematic side view of this attachment device 21 according to Figure 2.

[0026] The coupling device 33 consists of two cheeks 36 arranged at a distance from one another. The cheeks 36 can be connected to at least one connecting plate 34 which extends between the cheeks 36. The at least one connecting plate 34 can rest against an upper side of the rotating device 22 and can preferably be releasably fastened thereto. Each cheek 36 comprises a coupling bearing point 37 and an attachment bearing point 38. The coupling bearing point 37 and the attachment bearing point 38 are arranged offset in height from one another. The attachment bearing point 38 is recessed relative to the coupling bearing point 37. The attachment bearing point 38 can also be offset towards a rotation plane 39 of the rotating device 22 or lie in this rotation plane 39. The attachment bearing point 38 is offset laterally outwards relative to the attachment device 21, in particular the rotating device 22, or is assigned to an end face of the rotating device 22.

[0027] The rotating device 22 further comprises a rotary union 71, through which hydraulic lines can be passed through the rotating device 22 in order to be coupled to a working device 25. This can be used to control, for example, a shear, a gripper, or another drive such as a vibrating drive or the like.

[0028] Figure 4 schematically shows a control circuit 44 of the rotary drive 24 for controlling a rotary movement of the rotating device 22 or the working device 25. A worm drive 46 is provided in a housing 45 of the rotary drive 24. This comprises a worm 47 that meshes with a worm wheel 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 piston pump motor. This hydraulic motor 49 is controlled via a first supply line 51 and a second supply line 52. These supply lines 51, 52 are connected to a changeover valve 53. This changeover valve 53 is preferably a 4 / 2-way valve.

[0029] The switching valve 53 is connected to a tank 57 via a hydraulic line 68. Hydraulic fluid is supplied from the tank 57 to the switching valve 53 via a pump 54 through the hydraulic line 68. Furthermore, a hydraulic line 69 is connected to the switching valve 53, which serves as a return line and opens into a tank 57.

[0030] The control circuit 44 has a drive-side region extending between the tank 57 and the switching valve 53. The control circuit 44 has a work-side region extending between the hydraulic motor 49 and the switching valve 53.

[0031] Depending on the switching position of the switching valve 53, the first supply line 51 can be subjected to a working pressure of the hydraulic fluid. In this case, a rotary movement of the rotary drive 24 is controlled in a first direction of rotation, for example, a clockwise rotation. The second supply line 52 serves to return the working fluid to the tank 57. After the switching valve 53 is switched, a switch to controlling the supply line 52 with the working pressure can occur, so that the second supply line 52 is subjected to the working pressure and the hydraulic motor 49 is controlled in a second direction of rotation, for example, a counterclockwise rotation. Thus, both the first supply line 51 and the second supply line 52 can form an inlet to the hydraulic motor 49 or an outlet from the hydraulic motor 49.

[0032] 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 is provided 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 an excessive pressure in the hydraulic fluid. Thus, in the event of an excessive working pressure in the supply line 51 or an excessive working pressure in the supply line 52, the pressure relief valve 61, 62 can be opened quickly in order to prevent an excessive pressure on the rotary drive 24. At least one secondary valve 60 is provided in the working-side area of ​​the control circuit 44. The at least one secondary valve 60 is directly assigned to the changeover valve 53.Preferably, the changeover valve 53 and the first secondary valve 60 are positioned in the superstructure 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 a 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 the pressure is applied to the hydraulic motor 49. The at least one pressure relief valve 61, 62 can be provided on the attachment device 21, preferably within the housing 45 of the rotary drive 24. This at least one pressure relief valve 61, 62 can also be provided near the rotary drive 24. The positioning can also be provided on a stick 14 adjacent to the coupling device 33.The spatial proximity of the 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.

[0033] Figure 5 shows a schematic sectional view of the rotary drive 24. The worm 47 is mounted at its respective ends. The hydraulic motor 49 engages one of the ends of the worm 47. The worm 47 drives the worm wheel 48, whose rotational axis lies on the rotational axis 26 of the rotating device 22.

[0034] The above-described rotary drive 24 with the control circuit 44 provides increased sensitivity when an overload occurs on the consumer side or the work side. The setting range of the pressure relief valves 61, 62 for the drive-side overload for controlling the hydraulic motor 49 lies below the absolute overload or borders on the absolute overload at which at least one secondary valve 60 opens. This can increase work safety. This becomes clear from the following application described as an example: 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 rotated orientation relative to the gripping object. A closing movement of the shears is then controlled, whereby, for example, the shears cannot cut the gripping object due to the tilted position.This would, however, result in the pressure buildup via the pump 54 leading to an excess pressure in the control circuit 44, particularly on the consumer side, which could cause the entire machine or the excavator 11 to tip towards the gripping object. However, the control circuit 44 makes it possible for one of the two pressure relief valves 61, 62 to open on the consumer side in the event of an excess pressure compared to a preset working pressure, which is preferably below the absolute overload, so that the hydraulic motor 49 is no longer supplied with hydraulic fluid to control a rotary movement. Due to the design of the worm drive 46 without self-locking, the shears can align themselves towards the gripping object. The machine or the excavator 11 remains stationary without rotating towards the gripping object. The closing movement of the shears orof the work device can be further controlled in order to continue the work process.

Claims

Claims Rotary drive for the rotary positioning of a working device (25) on a machine or an excavator (11), - with a worm drive (46) comprising 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) acts on a shaft end of the screw (47), - wherein the control circuit (44) comprises a changeover valve (53) which controls a first and a second supply line (51, 52) leading to the at least one hydraulic motor (49), wherein for controlling a first direction of rotation of the rotary drive (24), the first supply line (51) is supplied with a hydraulic fluid and for controlling a second direction of rotation of the rotary drive (24), the second supply line (52) is supplied with hydraulic fluid, characterized in that - that at least one pressure relief valve (61, 62) is provided between the first and the second supply line (51, 52), which opens when the working pressure of the hydraulic fluid in the supply line (51, 52) pressurized with hydraulic fluid is excessive, and that the worm (47) and / or the worm wheel (48) are designed with a thread pitch without self-locking. Rotary drive according to claim 1, characterized in that at least one short-circuit line (63, 64) is provided between the first and second supply lines (51, 52), and the at least one pressure-limiting valve (61, 62) is provided in the at least one short-circuit line (63, 64). Rotary drive according to claim 1 or 2, characterized in that a first pressure-limiting valve (61) and a second pressure-limiting valve (62) are connected between the first and second supply lines (51, 52), which act in opposite directions and open when the pressure of the hydraulic fluid in the supply lines (51, 52) increases. Rotary drive according to one of the preceding claims, characterized in that an opening pressure of the at least one pressure-limiting valve (61, 62) is adjustable or controllable.Rotary drive according to one of the preceding claims, characterized in that the first and second pressure-limiting valves (61, 62) can be set to the same opening pressure. Rotary drive according to one of the preceding claims, characterized in that the at least one pressure-limiting valve (61, 62) can be set to an opening pressure between 10 bar and 600 bar. Rotary drive according to one of the preceding claims, characterized in that the opening pressure of the at least one pressure-limiting valve (61, 62) can be adjusted electrically or can be switched in stages or continuously. Rotary drive according to one of the preceding claims, characterized in that the worm drive (46) is supplied with lubrication. 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. Rotary drive according to one of the preceding claims, characterized in that the changeover valve (53) is designed as a 4 / 2-way valve. 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 close to the housing (45) of the rotary drive (24) on the consumer side between the changeover valve (53) and the hydraulic motor (49).Rotary drive according to one of the preceding claims, characterized in that the control circuit (44) has at least one secondary valve (60) on the working side between the changeover valve (53) and the rotary drive (24), 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. Rotary drive according to one of the preceding claims, characterized in that the adjustable opening pressure of the at least one pressure-limiting valve (61, 62) is smaller than the opening pressure of the absolute overload of the at least one secondary valve (60).

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