Robot, load compensation arrangement for a robot, and installation method

Abstract

A fluidic load compensation arrangement (60, 160) for a multi-axis robot (10, 110), which has at least two coupling members (14, 16, 18) connected in an articulated manner to one another, comprises a cylinder (62, 182) which is connected in an articulated manner to a first coupling member (14, 16, 18) and a second coupling member (14, 16, 18) of the robot (10, 110) in order to store energy during a relative movement between the first coupling member (14, 16, 18) and the second coupling member (14, 16, 18) and to release stored energy. The load compensation arrangement (60, 160) has a first pivot joint (68, 188), via which a first end of the cylinder (62, 182) is mounted in a rotatable manner on the first coupling member, and a second pivot joint (70, 190), via which a second end of the cylinder (62, 182) is mounted in a rotatable manner on the second coupling member. At least the first pivot joint (68, 188) or the second pivot joint (70, 190) comprises a spherical sliding bearing (230). A robot (10, 110) uses such a load compensation arrangement (60, 160). A method is used to install a spherical sliding bearing (230) in a load compensation arrangement (60, 160).

Description

Robot, load balancing arrangement for a robot and assembly method

[0001] The present disclosure relates to a fluidic load balancing arrangement for a multi-axis robot having at least two articulated coupling members that are movable relative to one another, in particular pivotable. The present disclosure further relates to a robot with a load balancing arrangement and a method for mounting a plain bearing in a load balancing arrangement.

[0002] Multi-axis robots, in particular so-called industrial robots, are well known in the art. Such robots usually comprise two, three or more interconnected and relatively movable coupling elements. For example, these coupling elements can be referred to as a frame, swing arm, arm / boom, hand, etc. General robots usually have a serial kinematic chain. Such robots are also referred to as articulated arm robots. Robots with two to seven or even more axes of rotation or swivel axes are known. With serial kinematics, the coupling elements of the robot, starting from the frame, form a serial chain. This means that a drive on the frame orOn coupling links arranged close to the frame in the kinematic chain, not only the directly following coupling link, but also, if necessary, other coupling links in the kinematic chain, must be held and / or moved toward an end link. This leads to increased holding torques and, in general, to an increase in load and inertia.

[0003] An industrial robot is generally understood to be a handling machine equipped with appropriate tools for the autonomous handling of objects and programmable along multiple axes of movement, particularly with regard to orientation, position, and workflow. Industrial robots essentially comprise a control device and a robot arm with multiple axes and, if appropriate, levers that are moved by drives controlling the control device. Industrial robots, particularly industrial robots with a relatively large payload, can have a weight or mass balancing system for at least one of their axes, particularly for the second axis of the kinematic chain or the horizontal axis, which system comprises, for example, a helical spring or other energy storage device.

[0004] Load balancing assemblies for robots are typically arranged between two adjacent coupling elements that are movable, in particular pivotable, relative to one another. Various types of load balancing assemblies are known, for example, purely mechanical mass-based balancing assemblies, spring-based load balancing assemblies, fluidic load balancing assemblies, etc. The aim of such a load balancing assembly is fundamentally to store static and / or kinematic energy during the movement of the robot's coupling elements relative to one another in order to make this energy available again, for example, during a counter-directional movement. In this way, unfavorable load situations or extreme positions of the robot's coupling elements can be optimized to reduce the holding torque or load torque required by the drive.

[0005] From WO 96 / 31325 A1 a multi-axis industrial robot is known, having a frame, a rocker arm, a boom and a robot hand which are articulated to one another and driven, wherein the rocker arm is arranged laterally next to the system plane formed by the frame axis and the center of the hand flange, wherein the rocker arm and the boom each have a one-sided cantilevered bearing, wherein the rocker arm is connected to a static hydraulic mass balance which is arranged on its side of the system plane, wherein the gear and the bearing of the rocker arm are arranged on one side of the system plane, and wherein the motor of the rocker arm is arranged on the other side of the system plane.

[0006] Load balancing arrangements for robots are further disclosed in EP 2 301 727 A1 and DE 102014 104 173 A1. Relevant load balancing arrangements are also known from EP 3 311 961 A1 and EP 3 311 962 A1.

[0007] It has been shown that the coupling of such load balancing arrangements to the coupling links of robots places increased demands on accuracy. Any axial deviations and / or tilt angles between the steered elements on the robot side and the load balancing device coupled to its coupling links can have an adverse effect on the operating behavior and service life of the load balancing device and the robot as a whole. Under certain circumstances, the kinematic chain formed by the coupling links of the robot and the load balancing device coupled to them may become over-determined, which in turn leads to increased wear and increased force expenditure.

[0008] Furthermore, deformations can occur, at least temporarily, under high loads, which also have adverse effects on operational behavior and service life. Conversely, a robot, including its load-balancing device, should still be designed to be sufficiently compact and lightweight, so certain tolerance fluctuations and static / dynamic compliances are to be expected.

[0009] Against this background, the present disclosure is based on the object of providing a fluidic load balancing arrangement for a multi-axis robot, as well as a robot equipped with such a load balancing arrangement, which are designed to be sufficiently robust and resilient. The load balancing arrangement should be suitable for heavy loads and changing directions of movement. The load balancing arrangement should be capable of being integrated into a robot or coupled to its coupling elements with moderate effort.

[0010] According to a first aspect, the present disclosure relates to a fluidic load balancing arrangement for a multi-axis robot comprising at least at least two coupling links which are connected to one another in an articulated manner, the load balancing arrangement comprising: a cylinder which is connected in an articulated manner to a first coupling link and a second coupling link of the robot in order to store energy and to release stored energy during a relative movement between the first coupling link and the second coupling link, a first rotary joint via which a first end of the cylinder is rotatably mounted on the first coupling link, and a second rotary joint via which a second end of the cylinder is rotatably mounted on the second coupling link, at least one of the first rotary joint and the second rotary joint comprising a spherical plain bearing.

[0011] The object of the present disclosure is achieved in this way.

[0012] The spherical plain bearing allows for a high load-bearing capacity and, at the same time, is well-suited for alternating directions of movement (oscillating motion), which are frequently encountered in robots. The spherical design of the plain bearing increases its ability to compensate for any shape deviations and / or bearing deviations. In particular, a spherical plain bearing can effectively compensate for any misalignment of the cylinder or its rotary joints. In this way, for example, an axial offset between the first rotary joint and the second rotary joint can be easily compensated. This allows for safe operation of the robot equipped with the load balancing arrangement, ensuring a long service life.

[0013] Any coupling points for accommodating the swivel joints between the robot's coupling elements and the cylinder of the load balancing assembly may be subject to tolerances within certain limits. This applies, for example, to the axial alignment of two pivotally coupled robot coupling elements that are additionally functionally coupled via the load balancing assembly.

[0014] Due to its tolerance insensitivity, any deformations and / or load peaks during robot operation have only a minimal impact on the function and service life of the load balancing arrangement. Furthermore, any bearing reactions in the robot that may occur due to overdetermination can be minimized, thus reducing the risk of damage and / or excessive wear on the robot side as well.

[0015] A spherical plain bearing is a self-aligning joint bearing for heavy loads. The spherical plain bearing can withstand high shock loads and compressive loads, even during non-constant, oscillating movements. A spherical plain bearing exhibits a favorable ratio between load capacity and required installation space, allowing the load balancing arrangement to be designed compactly. Any coupling points with the robot's coupling links can be designed with moderate installation space requirements. Thanks to its tolerance compensation capability, the spherical plain bearing can be adapted to current operating conditions during robot movement. In this way, for example, it can react to misalignment (e.g., angular misalignment between the involved axes) that changes depending on the relative position between the involved coupling links.

[0016] For the purposes of the present disclosure, a spherical plain bearing comprises, for example, a circumferential ring with a spherically (convexly) curved outer surface adapted to a seat for the bearing. The seat has a spherical recess with a concave curvature. In other words, the spherical plain bearing can be pivoted (at least within certain limits) during operation along the spherical surfaces of the seat to compensate for misalignment and / or other shape and / or positional deviations between the elements to be coupled. Nevertheless, a high load-bearing capacity is ensured due to the planar contact along the spherical surfaces.

[0017] Plain bearings can be made of metal, plastic, and ceramic, for example. Plain bearings designed as metal-polymer plain bearings or fiber-reinforced composite bearings are also known. Plain bearings can be maintenance-free or low-maintenance. Preferably, plain bearings are designed as a single piece and are formed, for example, by a (single) bearing ring

[0018] According to an exemplary embodiment of the load balancing arrangement, both the first pivot joint and the second pivot joint comprise a spherical plain bearing. This further increases the tolerance compensation capability. Since the distance between the first pivot joint and the second pivot joint changes when the coupled coupling elements of the robot are pivoted relative to each other, an adjustment / alignment of at least one of the two plain bearings can occur during the movement.

[0019] According to another exemplary embodiment of the load balancing arrangement, the first coupling element and the second coupling element of the robot are adjacent to one another and pivotably coupled via an axis. Furthermore, the two coupling elements are connected to one another via the load balancing arrangement, thus reducing the risk of static overdetermination. By coupling the load balancing arrangement with a tolerance-compensating spherical plain bearing, the accuracy requirements for the manufacturing and assembly of the components involved can be reduced without adversely affecting the operating behavior and service life.

[0020] According to another exemplary embodiment of the load balancing arrangement, at least the first pivot joint or the second pivot joint is radially spaced from the axis between the coupling links. In this way, the distance between the first pivot joint and the second pivot joint changes upon relative rotation between the first coupling link and the second coupling link. If an inclination between the axes of the first and second pivot joints already exists, this inclination would possibly change depending on the respective pivot angle. At least one spherical plain bearing can be used to respond to any fluctuations.

[0021] According to a further exemplary embodiment of the load balancing arrangement, at least the first pivot joint or the second pivot joint is axially spaced from an effective bearing plane of the axle. Within the scope of the present disclosure, the effective bearing plane is oriented perpendicular to the axle, wherein the effective bearing plane defines a contact surface in which the first coupling member and the second coupling member are adjacent to one another and rotatable relative to one another.

[0022] Robots often feature a cantilevered bearing between two adjacent coupling links. With such a design, the effective bearing plane is the interface between the two coupling links. The associated swivel joint of the load balancing assembly often cannot be positioned precisely in this bearing plane. If there is an (axial) distance to the bearing plane, a tilting moment must be expected if forces / moments are transmitted via both the robot's coupling links and the load balancing assembly's cylinder. This can lead to deformations during operation, depending on the respective relative pivoting and / or the current load. Even in such a case, the spherical plain bearing can perform corresponding compensating movements.

[0023] According to a further exemplary embodiment of the load balancing arrangement, the first pivot joint and the second pivot joint each have a structural center, wherein the center of the first pivot joint and the center of the second pivot joint are axially offset from one another. For example, the axial offset is in the range of a few hundredths of a millimeter to a few tenths of a millimeter. Such an offset can cause a misalignment, so that the coupling elements involved and the cylinder connecting them are not perfectly parallel to one another. However, if at least one of the two pivot joints is equipped with a spherical plain bearing, adaptation to such a positional deviation can be achieved without adversely affecting function.

[0024] According to a further exemplary embodiment of the load balancing arrangement, the first rotary joint and the second rotary joint each have an axis, wherein the axis of the first rotary joint and the axis of the second rotary joint are at least temporarily aligned during the relative movement between the first coupling member and the second coupling link are not aligned parallel to each other. Such tilting can also be compensated by at least one spherical joint bearing.

[0025] Non-parallel alignment typically refers to a slight inclination / tilt / skew between the nominally parallel axes. For example, a maximum inclination of 0.5° may occur during operation. For example, a maximum inclination of 2.0° may occur during operation. For example, a maximum inclination of 5.0° may occur during operation. Such inclination angles can be compensated. Accuracy requirements for the structural integration of a load balancing arrangement can be reduced.

[0026] The general goal is to couple the individual elements (coupling links) of the robot's kinematic chain with high rigidity, resulting in minimal compliance during operation and, in particular, high repeatability for positioning. In this context, it is advantageous if the load balancing arrangement is capable of compensating for any tolerances in its swivel joints. This avoids adverse effects on the rigidity and accuracy of the robot's kinematic chain.

[0027] According to a further exemplary embodiment of the load balancing arrangement, at least the first pivot joint or the second pivot joint has a recess, at least partially spherically designed, for receiving the spherical plain bearing, which is formed in the cylinder. In other words, the cylinder has, for example, an eyelet for receiving a bearing on at least one of its two opposite ends. The eyelet comprises a spherical recess that serves as a seat for the spherical plain bearing.

[0028] It is understood that both the spherical recess and the spherical plain bearing do not have a (complete) spherical shape. Instead, they usually have a spherical segment shape.

[0029] The coupling with the coupling link of the robot can be achieved, for example, via a bolt (bearing bolt) that is attached to the coupling link of the robot and extends through the spherical plain bearing.

[0030] According to a further exemplary embodiment of the load balancing arrangement, at least the first pivot joint or the second pivot joint has a recess, at least partially spherically designed, for receiving the spherical plain bearing, which is formed in the coupling element of the robot. In other words, according to this embodiment, the eye for receiving the spherical plain bearing is not formed in the cylinder of the load balancing arrangement, but in the coupling element of the robot. Accordingly, in this embodiment, a bolt extending through the spherical plain bearing is formed at the first end or second end of the cylinder.

[0031] In an exemplary embodiment of the load balancing arrangement, the cylinder is suspended from a coupling element of the robot via the spherical plain bearing, at least at its first or second end. With a suspended bearing, increased bending moments and deformations must be expected. The spherical plain bearing can adapt to a given load condition.

[0032] According to a further exemplary embodiment of the load balancing arrangement, the recess, which is at least partially spherically designed, has at least on one side of its circumference an insertion aid for mounting the spherical plain bearing in an installation orientation inclined by at least 60° with respect to the installation orientation.

[0033] In this way, the spherical plain bearing can be easily installed even if both the plain bearing and the recess for its mounting are designed as a single piece. The mounting orientation (in which the plain bearing is inserted into the seat) is usually rotated by 90° relative to the installation orientation (when the plain bearing is installed). It is understood that installation, for example, in an orientation with an angle of 80° to 100° (for example, 85° to 95°) relative to the Installation orientation may be possible. In other words, the plain bearing can be oriented transversely to its final installation position and inserted into the seat. This can already establish contact between the spherical surfaces of the plain bearing and the recess, after which the plain bearing is rotated into its final installation orientation.

[0034] According to a further exemplary embodiment of the load balancing arrangement, the insertion aid has at least one flattened area or two flattened areas offset by 180° on the circumference of the recess, which is at least partially spherically designed. In the installed state, the plain bearing is positively received in its seat. However, this positive-locking contour is at least partially interrupted in order to form the insertion aid, in which the plain bearing can be inserted into the seat transversely to its final installation orientation. Even if certain pivoting movements are tolerated in the installation orientation, a secure fit is nevertheless guaranteed because usual compensating movements (in response to given tilt angles) are significantly smaller than the pivot angle between the installation orientation and the assembly orientation.

[0035] According to a further aspect, the present disclosure relates to a robot, in particular an industrial robot in the form of an articulated arm robot, which is provided with a load balancing arrangement according to at least one of the embodiments described herein, which is assigned to two coupling members of the robot which are connected to one another in an articulated manner.

[0036] According to an exemplary embodiment of the robot, the load balancing device is associated with a coupling member designed as a carousel and a coupling member designed as a rocker, wherein the cylinder is articulated on rotary joints that are radially spaced from a rotation axis between the two coupling members.

[0037] According to a further embodiment of the robot, the cylinder is arranged in such a way that, at a maximum relative movement between the carousel and the rocker, the hydraulic cylinder performs both a retraction movement and a This results in an extension movement. A maximum relative movement can, for example, include a pivoting movement between the two coupling links involved, encompassing the largest possible pivot angle. Depending on the forces and moments expected at the coupling links, whether from the robot itself or from the load being carried, the load balancing arrangement can thus reduce the applied moments in a variety of operating conditions.

[0038] According to another exemplary embodiment of the robot, the load balancing arrangement comprises two cylinders assigned to different degrees of freedom of movement of the robot, i.e., different pairs of coupling links. In such a case, it is also advantageous if the two cylinders are each mounted at their pivot joints via at least one spherical plain bearing on the respective associated coupling link.

[0039] According to a further exemplary embodiment of the robot, the first rotary joint and the second rotary joint each have a structural center, wherein the center of the first rotary joint and the center of the second rotary joint are axially offset from one another, and wherein the offset is compensated for in the load balancing arrangement by the spherical plain bearing.

[0040] According to a further exemplary embodiment of the robot, the first rotary joint and the second rotary joint each have an axis, wherein the axis of the first rotary joint and the axis of the second rotary joint are at least temporarily aligned non-parallel to one another during the relative movement between the first coupling member and the second coupling member, and wherein the non-parallelism is compensated for in the load balancing arrangement by the spherical plain bearing.

[0041] According to another aspect, the present disclosure relates to a method for assembling a spherical plain bearing in a load balancing arrangement comprising the following steps: Provision of the spherical plain bearing in the assembly orientation, Inserting the spherical plain bearing into the spherical recess using the assembly aid, whereby the spherical plain bearing is in the assembly orientation when the spherical plain bearing is in the spherical recess, pivoting the spherical plain bearing into the installation orientation, Securing the position of the spherical plain bearing in the spherical recess by inserting a bolt into the spherical plain bearing on one of the coupling members, and in particular compensating for an axial offset and / or a non-parallelism between the first rotary joint and the second rotary joint by the spherical plain bearing.

[0042] The object of the present disclosure is also achieved in this way.

[0043] It is understood that the features of the invention mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.

[0044] Further advantages and features of the invention will become apparent from the following description of several preferred embodiments with reference to the drawings. They show: Fig. 1 is a schematic side view of an embodiment of a robot provided with a load balancing arrangement, in a retracted state; Fig. 2 is a side view of another embodiment of a robot provided with a load balancing arrangement in a retracted state according to Fig. 1; Fig. 3 is a further schematic view of a robot with a load balancing arrangement in an orientation rotated by 90° compared to Fig. 1; Fig. 4 is a partial side view of a cylinder with an eye having a seat for receiving a spherical plain bearing; Fig. 5 is a partial side view based on Fig. 4 to illustrate a compensating movement of the spherical plain bearing; and Fig. 6 is a partial perspective view of a cylinder with an eye having a spherical recess and a spherical plain bearing to illustrate an assembly process.

[0045] With reference to Fig. 1 and with additional reference to Fig. 2 and Fig. 3, basic designs of robots and load balancing arrangements for robots are explained.

[0046] Fig. 1 shows a side view of a robot 10, which is designed approximately as an industrial robot. The robot 10 is designed as an articulated-arm robot or a knuckle-arm robot. The robot 10 has a serial kinematic chain.

[0047] For example, the robot 10 comprises coupling links 12, 14, 16, 18, 20, 22, and 24, which are coupled to one another in series. Each of the coupling links 12, 14, 16, 18, 20, 22, and 24 is movable, in particular rotatable or pivotable, relative to its adjacent coupling link(s). The first coupling link 12 can also be referred to as the base. A connection 26 is provided on the last coupling link 24, for example, for a so-called end effector. The kinematic chain can be supplemented with further coupling links. For example, a manipulator in the form of a gripper or the like can be accommodated at the connection 26.

[0048] The robot 10 has various (movement) axes 30, 32, 34, 36, 38, 40, each formed between two of the coupling links 12, 14, 16, 18, 20, 22 and 24. The axes 30, 32, 34, 36, 38, 40 can also be referred to as drive axes. and be equipped with or coupled to drives / motors, such as electric motors. Gearboxes can be interposed between axes 30, 32, 34, 36, 38, 40 and the motors associated with them. Axes 30, 32, 34, 36, 38, 40 generally allow a rotary / pivoting movement between adjacent coupling links 12, 14, 16, 18, 20, 22, and 24.

[0049] The axis 30 is arranged between the coupling links 12, 14 and allows a relative pivoting or relative rotation between the coupling links 12, 14. The axis 32 is arranged between the coupling links 14, 16 and allows a relative rotation or relative pivoting between the coupling links 14, 16. The axis 34 is assigned to the coupling links 16, 18 and allows a relative rotation and relative pivoting between the coupling links 16, 18. The axis 36 is arranged between the coupling links 18, 20 and allows a relative rotation or relative pivoting between the coupling links 18, 20. The axis 38 is arranged between the coupling links 20, 22 and allows a relative rotation or relative pivoting between the coupling links 20, 22. The axis 40 is arranged between the coupling links 22, 24 and allows a relative rotation or relative pivoting between the coupling links 22, 24.

[0050] In the robot 10 illustrated in Fig. 1, the coupling link 12 can also be referred to as a frame 42. The coupling link 14 can also be referred to as a carousel 44. The coupling link 16 can also be referred to as a rocker arm 46. The coupling link 18 can also be referred to as an arm 48. The frame 42 is typically designed to fix the robot 12 to the floor. However, designs of robots 10 are also known that are mounted, for example, on the ceiling or on a (side) wall, depending on the application.

[0051] The robot 10 is further provided with a load balancing arrangement 60, which, according to the exemplary embodiment illustrated in Fig. 1, comprises a cylinder (for example, a hydraulic cylinder) 62 having a cylinder housing 64 and a piston rod 66 that extends into the cylinder housing 64. The cylinder housing 64 and the piston rod 66 are translationally movable relative to one another. The cylinder 62 is supported at one end, at the cylinder housing 64, via a bearing or a Swivel joint 68 is pivotally coupled to the coupling member 14, i.e. to the carousel 44. The hydraulic cylinder 62 is received on the coupling member 16, i.e. on the rocker 46, via a further end, which is provided on the piston rod 66, via a bearing or a swivel joint 70. The swivel joints 68, 70 are each arranged eccentrically to or radially offset from the axis 32. Upon relative pivoting between the coupling members 14, 16, a relative movement occurs between the piston rod 66 and the cylinder housing 64. In this way, a fluid, for example hydraulic oil or a gas, can flow into the cylinder housing 64 or be displaced from the cylinder housing 64.

[0052] The load balancing arrangement 60 further comprises an accumulator unit 74, which includes at least one pressure accumulator 78. The accumulator unit 74 and the pressure accumulator 78 are shown only schematically in Fig. 1. The pressure accumulator is designed, for example, as a diaphragm accumulator, bladder accumulator, piston accumulator, spring accumulator and / or according to another accumulator design. For example, a gaseous fluid, such as nitrogen or the like, is accommodated in the pressure accumulator 78. In contrast to the hydraulic fluid, the gaseous fluid is highly compressible, so that the oil displaced during the movement of the cylinder 62 can pressurize the gaseous fluid in the pressure accumulator 78. In this way, potential energy or kinetic energy can be stored as fluid energy.

[0053] During the transition between the folded-in position according to Fig. 1 and a folded-out position, the coupling member 16 is pivoted relative to the coupling member 14 in such a way that the piston rod 66 initially plunges deeper into the cylinder housing 64 and, after overcoming a maximum immersion depth, is moved out of the cylinder housing 64 again when the coupling member 16 is pivoted further.

[0054] With reference to Fig. 2, a further embodiment of a robot, designated overall by 110, is illustrated. The robot 110 according to Fig. 2 is fundamentally similar to the robot 10 according to Fig. 1. This applies in principle to the coupling links 12, 14, 16, 18, 20, 22, 24 as well as the axes 30, 32, 34, 36, 38 and 40 assigned to them. In the robot 110, the coupling link 12 can also be referred to as a frame 42. Accordingly, the coupling link 14 can be referred to as a carousel 44. The coupling link 16 can be referred to as a rocker arm 46. The coupling link 18 can be referred to as an arm 48.

[0055] The robot 110 is also provided with a load balancing arrangement, designated 160 in Fig. 2. The load balancing arrangement 160 is provided with a cylinder (for example, a hydraulic cylinder) 62, the design of which is fundamentally similar to the design of the cylinder 62 according to Fig. 1.

[0056] The cylinder 62 comprises a cylinder housing 64 and a piston rod 66. At its cylinder-housing end, the cylinder 62 is mounted on the coupling member 14 via a bearing or a swivel joint 68. At a piston-side end, the cylinder 62 is mounted on the coupling member 16 via a bearing or a swivel joint 70. Analogous to the load balancing arrangement 60 according to Fig. 1, the load balancing arrangement 160 is also provided with a storage unit 74, which comprises at least one pressure accumulator 78. The storage unit 74 is assigned to the cylinder 62 and, in particular, is mounted on the cylinder housing 64.

[0057] However, the load balancing arrangement 160 further includes a second cylinder (e.g., hydraulic cylinder) 182. The cylinder 182 is shown largely in dashed lines in Figs. 2 and 4. The cylinder 182 is associated with the second coupling member 16 and the third coupling member 18. In the exemplary view orientation on which Fig. 2 is based, the cylinder 182 is at least partially concealed by the second coupling member 16.

[0058] The cylinder 182 comprises a cylinder housing 184 and a piston rod 186 that can be inserted into and extended from the cylinder housing 184. The cylinder 182 is mounted on the coupling member 16 at its cylinder housing end via a bearing or pivot joint 188. The cylinder 182 is mounted on the coupling member 18 at its piston end via a bearing or pivot joint 190.

[0059] The pressure accumulator 78 or a second pressure accumulator can, in principle, also be provided in the second cylinder 182. Nevertheless, the configuration shown in Fig. 2 is conceivable, in which the second cylinder 182 is indirectly coupled to the pressure accumulator 78 of the first cylinder 62 via the first cylinder 62.

[0060] The pivot joints 68, 70 of the cylinder 62 are each offset from the axis 32 or radially spaced therefrom. The pivot joints 188, 190 of the cylinder 182 are each offset from the axis 34 or radially spaced therefrom.

[0061] The cylinder 182 is accommodated between the rocker 46 and the arm 48 of the robot 110 according to the exemplary nomenclature mentioned above.

[0062] The exemplary embodiment shown in Fig. 2 further includes a connecting line 194 extending between cylinder 62 and cylinder 182. The connecting line 194 establishes a fluidic coupling between the cylinders 62, 182. The connecting line 194 extends, for example, from the cylinder housing 64 to the cylinder housing 184. In this way, the cylinders 62, 182 of the load balancing arrangement 160 are functionally coupled to one another.

[0063] A further feature of the exemplary design of the load balancing arrangement 160 according to Fig. 2 is that the cylinder 182, which is arranged between the coupling member 16 and the coupling member 18, does not have a storage unit equipped with a pressure accumulator. Instead, the cylinder 182 also uses the storage unit 74 provided with the cylinder 62. For this purpose, the connecting line 194 extends between the cylinder 182 and the cylinder 62, in particular between the cylinder housings 64, 184.

[0064] An advantage of the design of the load balancing arrangement 160 illustrated in Fig. 2 is that no separate storage unit 74 with at least one pressure accumulator 78 is provided for the second cylinder 182 itself. This avoids an increase in the inertial masses that must be overcome by the axle 32 or the drive motor of the axle 32 in order to move the coupling member 16 and the following coupling links 18, 20, 22, 24 relative to the coupling link 14. Furthermore, no further effort is required for these components.

[0065] In addition to Figures 1 and 2, Fig. 3 illustrates another view orientation of a robot designated 10. The robot 10 is rotated by approximately 90° relative to the view orientation shown in Fig. 1. Fig. 3 shows the side of the robot 10 that faces away from the coupling element 24 or the connection 26 in the orientation according to Fig. 1.

[0066] The cylinder 62 of the load balancing arrangement 60 is shown only schematically in Fig. 3. The cylinder 62 is connected to the coupling member 14 via a pivot joint 68 and to the coupling member 16 via a pivot joint 70. An axis 210 extends through the pivot joint 68. An axis 212 extends through the pivot joint 70. The axes 210, 212 should be aligned as parallel to one another as possible. In addition, the axes should be aligned parallel to the axis 32, about which the coupling members 14, 16 are pivotable relative to one another. In Fig. 3, a structural center of the pivot joint 68 is designated 214. Furthermore, a structural center of the pivot joint 70 is designated 216.

[0067] Ideally, the design centers 214, 216 are axially identically positioned. This is the case, for example, when the design center 214 and the design center 216 are positioned in a common plane oriented perpendicular to the axes 210, 212.

[0068] Fig. 3 further illustrates a bearing plane designated 220, which represents an "interface" that is decisive for the pivoting movement between the coupling links 14, 16. There, a relative rotation occurs between the two coupling links 14, 16. In other words, in the design according to Figures 1-3, the coupling link 16, designated, for example, as a rocker arm 46, is suspended from the coupling link 14, designated, for example, as a carousel 44. High forces and bending moments generally occur in a suspended bearing. A suspended bearing can be can be spoken of if any force application occurs "outside" the bearings or laterally offset from a bearing.

[0069] In the design shown in Fig. 3, it is further apparent that the first end of the cylinder 62 with the pivot joint 68 is also mounted in a floating manner on the coupling member 14, for example, on a bearing dome 222. The structural center 214 of the pivot joint 68 is spaced from the bearing plane 220. The second end of the cylinder 62 with the pivot joint 70 is arranged in the exemplary embodiment between two bearing legs 224 of the coupling member 16. There, there is no floating bearing for the pivot joint 70. Nevertheless, there is also an axial offset between the structural center 216 and the bearing plane 220.

[0070] Fig. 3 shows that even with perfectly designed orientation and alignment of the components involved, deformations can occur during operation of robot 10 due to the acting forces and moments, which could, for example, lead to misalignment between axes 210, 212. In such a case, increased friction and wear could potentially occur in cylinder 62. In principle, this unfavorable operating behavior could also affect the coupling elements 14, 16 and thus the operation of robot 10.

[0071] Furthermore, it must be taken into account that, for example, the design centers 214, 216 are not perfectly aligned with each other (axially), so that there is an axial offset which leads to a misalignment of the cylinder 62 and consequently in turn to an unfavorable alignment between the rotary joints 68, 70.

[0072] A misalignment between the axes 210, 212 and / or an axial offset between the centers 214, 216 can therefore adversely affect the operating behavior of the load balancing arrangement 60 and the overall operating behavior of the robot 10. Nevertheless, the bearing of the cylinder 62 at the rotary joints 68, 70 may have to withstand high forces and moments.

[0073] With reference to Figures 4-6, embodiments are illustrated in which spherical plain bearings are used in at least one of the pivot joints 68, 70 in order to compensate for positional tolerances and / or shape tolerances.

[0074] Fig. 4 shows a partial sectional view of the cylinder 62 at one of the pivot joints 68, 70. In the exemplary embodiment, an eye 226 is formed at the end of the cylinder 62, in which a spherically shaped recess 228 is formed. A spherical plain bearing 230 is seated in the spherically shaped recess 228. The spherical plain bearing has a spherical outer surface that is adapted to the spherical recess 228. In other words, both the spherical plain bearing 230 and the spherical recess 228 have spherical segment surfaces with the same diameter. The spherical plain bearing 230 is designed in one piece and provided with an opening for a bolt or the like, through which the axis 210 extends. The structural center 214 forms the center point of the spherical bearing 230 along the axis 210 in the exemplary embodiment.

[0075] The spherically shaped recess 228 can also be referred to as a seat for the spherical plain bearing. Fig. 4 illustrates an ideal orientation; accordingly, the axis 210 with the design center 214 is oriented concentrically with the design of the eye 226. The designation of the axis 210 and the design center 214 indicate that the eye 226 is formed at the first end of the cylinder 62 at the pivot joint 68. However, this is not to be understood as limiting. The second end of the cylinder 62 with the pivot joint 70 can also have such a design.

[0076] In Fig. 5, a bolt 240 is inserted into the spherical bearing 230. In the exemplary embodiment, the bolt 240 is arranged, for example, on the coupling member 14 or on the coupling member 16 in order to provide a bearing point for the first pivot joint 68 or the second pivot joint 70. In Fig. 5, an inclination between the axis 210 of the spherical bearing 230 and an axis 242 is indicated by the eye 226. Such an inclination (inclination between the axes 210, 242) can be compensated for both in static and dynamic conditions by a compensating movement of the spherical plain bearing 230 in the spherically shaped recess 228. Nevertheless, the matched spherical surfaces of the spherical plain bearing 230 (convexly curved, i.e., arched outwards) and the spherical recess 228 (concavely curved, i.e., arched inwards) still ensure a high load-bearing capacity. High loads and moments can be absorbed.

[0077] Fig. 6 illustrates an assembly process for mounting the spherical plain bearing 230 in the seat formed by the spherical recess 228 in the eye 226. An insertion aid 250 is formed on the circumference 248 of the spherical recess 228, at least on the end face shown in Fig. 6. The insertion aid 250 comprises at least one flattened portion 252, which is formed as a depression at the edge of the spherical recess 228. In the embodiment according to Fig. 6, two flattened portions 252, 254 are provided, which are offset from one another by 180° with respect to the axis 242. The flattened portions 252, 254 allow insertion of the spherical plain bearing 230 in the orientation shown in Fig. 6. The sliding bearing 230 is inclined with its axis 210 by approximately 90° (at least 60°, for example 80° to 100°, for example 85° to 95°) relative to the axis 242.

[0078] In other words, the plain bearing 230 can be inserted transversely, see arrow 260. In this way, taking into account the respective spherical shape of the plain bearing 32 and the recess 228, the center of the spherical plain bearing 32 can be brought into line or nearly into line with the center 214 of the spherical recess 228. The spherical plain bearing 230 can then be pivoted about an axis of rotation 264 that is perpendicular to the axis 210 of the spherical bearing 130 and perpendicular to the axis 242 of the spherical recess 228. See the curved arrow labeled 262. In this way, the spherical plain bearing 230 can assume the final installation orientation shown in Fig. 4, starting from the assembly orientation shown in Fig. 6. In the installation orientation and at small pivot angles (see Fig.5), the spherical plain bearing 230 is positively secured in the spherically shaped recess 228, particularly if a bolt 240 or a similar component also extends through the spherical plain bearing 230. Nevertheless, tool-free assembly is possible thanks to the insertion aid 250.

Claims

Patent claims 1. A fluidic load balancing arrangement (60, 160) for a multi-axis robot (10, 110) having at least two coupling members (14, 16, 18) connected to one another in an articulated manner, the load balancing arrangement (60, 160) comprising: a cylinder (62, 182) which is articulated to a first coupling member (14, 16, 18) and a second coupling member (14, 16, 18) of the robot (10, 110) in order to store energy and release stored energy during a relative movement between the first coupling member (14, 16, 18) and the second coupling member (14, 16, 18), a first rotary joint (68, 188) via which a first end of the cylinder (62, 182) is rotatably mounted on the first coupling member, and a second rotary joint (70, 190), via which a second end of the cylinder (62, 182) is rotatably mounted on the second coupling member, characterized in that at least the first rotary joint (68, 188) or the second rotary joint (70, 190) comprises a spherical plain bearing (230).

2. Load balancing arrangement (60, 160) according to claim 1, wherein the first pivot joint (68, 188) and the second pivot joint (70, 190) comprise a spherical plain bearing (230).

3. Load balancing arrangement (60, 160) according to claim 1 or 2, wherein the first coupling member (14, 16, 18) and the second coupling member (14, 16, 18) of the robot (10, 110) are adjacent to one another and are pivotally coupled to one another via an axis (32, 34).

4. Load balancing arrangement (60, 160) according to claim 3, wherein at least the first pivot joint (68, 188) or the second pivot joint (70, 190) are spaced radially from the axis (32, 34).

5. Load balancing arrangement (60, 160) according to claim 3 or 4, wherein at least the first pivot joint (68, 188) or the second pivot joint (70, 190) is axially spaced from an effective bearing plane (220) of the axle (32, 34).

6. Load balancing arrangement (60, 160) according to one of claims 1-5, wherein the first pivot joint (68, 188) and the second pivot joint (70, 190) each have a structural center (214, 216), wherein the center (214) of the first pivot joint (68, 188) and the center (216) of the second pivot joint (70, 190) are axially offset from one another.

7. Load balancing arrangement (60, 160) according to one of claims 1-6, wherein the first rotary joint (68, 188) and the second rotary joint (70, 190) each have an axis (210, 212), wherein the axis (210) of the first rotary joint (68, 188) and the axis (212) of the second rotary joint (70, 190) are at least temporarily aligned non-parallel to one another during the relative movement between the first coupling member (14, 16, 18) and the second coupling member (14, 16, 18).

8. Load balancing arrangement (60, 160) according to one of claims 1-7, wherein at least the first rotary joint (68, 188) or the second rotary joint (70, 190) has a recess (228) which is at least partially spherically designed for receiving the spherical plain bearing (230), which is formed in the cylinder (62, 182).

9. Load balancing arrangement (60, 160) according to one of claims 1-8, wherein at least the first rotary joint (68, 188) or the second rotary joint (70, 190) has a recess (228) which is at least partially spherically designed for receiving the spherical plain bearing (230), which is formed in the coupling member (14, 16, 18) of the robot (10, 110).

10. Load balancing arrangement (60, 160) according to claim 8 or 9, wherein the at least partially spherically designed recess (228) has at least one side on its circumference (248) an insertion aid (250) for mounting the spherical plain bearing (230) in a mounting orientation inclined by at least 60° with respect to the mounting orientation.

11. Load balancing arrangement (60, 160) according to claim 10, wherein the insertion aid (250) has at least one flattened portion (252, 254) or two flattened portions (252, 254) offset by 180° on the circumference (248) of the at least partially spherically shaped recess (228).

12. Robot (10, 110), in particular an industrial robot in the form of an articulated arm robot, with a load balancing arrangement (60, 160) according to one of the preceding claims, which is assigned to two coupling members (14, 16, 18) of the robot (10, 110) which are connected to one another in an articulated manner.

13. Robot (10, 110) according to claim 12, wherein the first pivot joint (68, 188) and the second pivot joint (70, 190) each have a structural center (214, 216), wherein the center (214) of the first pivot joint (68, 188) and the center (216) of the second pivot joint (70, 190) are axially offset from one another, and wherein the offset in the load balancing arrangement (60, 160) is compensated by the spherical plain bearing (230).

14. Robot (10, 110) according to claim 12 or 13, wherein the first rotary joint (68, 188) and the second rotary joint (70, 190) each have an axis (210, 212), wherein the axis (210) of the first rotary joint (68, 188) and the axis (212) of the second rotary joint (70, 190) are at least temporarily non-parallel to one another during the relative movement between the first coupling member (14, 16, 18) and the second coupling member (14, 16, 18), and wherein the non-parallelism in the load balancing arrangement (60, 160) is compensated for by the spherical plain bearing (230).

5. A method for assembling a spherical plain bearing (230) in a load balancing arrangement (60, 160) according to claim 10 or 11, comprising the following steps: Providing the spherical plain bearing (230) in the assembly orientation, Inserting the spherical plain bearing (230) into the spherical recess (228) using the assembly aid (250), wherein the spherical plain bearing (230) is in the assembly orientation when the spherical plain bearing (230) is in the spherical recess (228), pivoting the spherical plain bearing (230) into the installation orientation, Securing the position of the spherical plain bearing (230) in the spherical recess (228) by inserting a bolt (240) into the spherical plain bearing (230) on one of the coupling members (14, 16, 18), and in particular compensating for an axial offset and / or a non-parallelism between the first rotary joint (68, 188) and the second rotary joint (70, 190) by the spherical plain bearing (230).

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