A parallel mechanism with internal and external pairs jointly driven

Abstract

The present invention discloses a parallel mechanism driven by inner and outer pairs, the parallel mechanism driven by inner and outer pairs comprises: a base, a moving platform, a first branch chain, a second branch chain and a third branch chain; the first branch chain has the same structure as the second branch chain, both comprising a universal pair connected to the base, a first rotating pair connected to the moving platform, and a first moving pair connected to both the universal pair and the first rotating pair; the third branch chain comprises a second moving pair connected to the base, a ball pair connected to the moving platform, and a second rotating pair connected to both the ball pair and the second moving pair; the first moving pair and the second moving pair are driving pairs. The present invention effectively improves the overall stiffness of the parallel mechanism by setting the first moving pair as an intermediate rod and the second moving pair directly connected to the base as driving pairs.

Description

Technical Field

[0001] The invention relates to the field of parallel structures, and in particular to a parallel mechanism with inner and outer pairs jointly driven. Background Art

[0002] At present, in the three-DOF one-lateral and two-rotation parallel mechanism used by hybrid machine tools and hybrid robots, the mobile drive pair is mainly located in the middle rod, that is, the internal drive method is adopted. This structural design and drive method make the parallel mechanism have a larger working space and easy to control, but it reduces the rigidity of the mechanism to a certain extent.

[0003] Therefore, the existing technology still needs to be improved and developed.

[0004] Invention patent content

[0005] The technical problem to be solved by the present invention is that, in view of the above-mentioned defects of the prior art, a parallel mechanism with internal and external pairs jointly driven is provided, aiming to solve the problem that the three-degree-of-freedom one-horizontal and two-rotation parallel mechanism with fixed rotation direction in the prior art mainly adopts the internal drive method, resulting in reduced stiffness of the mechanism.

[0006] The technical solution adopted by the present invention to solve the problem is as follows:

[0007] In a first aspect, an embodiment of the present invention provides a parallel mechanism driven by inner and outer pairs, wherein the parallel mechanism driven by inner and outer pairs comprises: a base, a moving platform arranged opposite to the base, a first branch chain, a second branch chain and a third branch chain connecting the base and the moving platform; the third branch chain is arranged between the first branch chain and the second branch chain;

[0008] The first branch chain has the same structure as the second branch chain, and both include a universal joint, a first moving joint, and a first rotating joint; the universal joint is connected to the base; the first rotating joint is connected to the moving platform; the first moving joint is connected to both the universal joint and the first rotating joint;

[0009] The third branch chain includes a second moving pair, a second rotating pair and a ball pair; the second moving pair is connected to the base; the ball pair is connected to the moving platform; the second rotating pair is connected to both the ball pair and the second moving pair;

[0010] The first moving pair and the second moving pair are driving pairs.

[0011] In one embodiment, the rotation direction of the universal joint includes a first rotation direction and a second rotation direction perpendicular to the first rotation direction;

[0012] The rotation direction of the first rotation pair is parallel to the second rotation direction;

[0013] The rotation direction of the second rotation pair is parallel to the first rotation direction.

[0014] In one embodiment, the universal joint includes a first U-shaped member and a second U-shaped member movably connected to the first U-shaped member;

[0015] The first U-shaped member is fixedly connected to the base, and the upper end of the first U-shaped member is provided with a first through hole, a second through hole, and a first rotating rod movably connected to the first through hole and the second through hole, and the first through hole is arranged opposite to the second through hole;

[0016] The second U-shaped member is fixedly connected to the first moving pair; the upper end of the second U-shaped member is provided with a third through hole, a fourth through hole, and a second rotating rod movably connected to the third through hole and the fourth through hole, and the third through hole is arranged opposite to the fourth through hole; the first rotating rod is perpendicular to and fixedly connected to the second rotating rod;

[0017] When the first rotating rod rotates relative to the first through hole and the second through hole, the universal joint rotates in the first rotating direction;

[0018] When the second rotating rod rotates relative to the third through hole and the fourth through hole, the universal joint is rotated in the second rotating direction.

[0019] In one embodiment, the first moving pair includes a first sliding groove and a first sliding rod slidably connected to the first sliding groove;

[0020] The first slide groove is fixedly connected to the universal joint, and the first slide rod is fixedly connected to the first rotational joint; the shape of the opening end of the first slide groove is adapted to the shape of the first slide rod, and the first slide groove is sleeved on the first slide rod.

[0021] In one embodiment, the first rotating pair includes a third U-shaped member, a third rotating rod rotatably connected to the third U-shaped member;

[0022] The third U-shaped member is connected to the moving platform, and a fifth through hole and a sixth through hole are provided at the upper end of the third U-shaped member, and the fifth through hole and the sixth through hole are arranged opposite to each other; the third rotating rod is movably connected to the fifth through hole and the sixth through hole; the third rotating rod is perpendicular to and fixedly connected to the first moving pair; the rotation direction of the third rotating rod is the rotation direction of the first rotating pair.

[0023] In one embodiment, the second moving pair includes a second slide groove and a second slide rod slidably connected to the second slide groove;

[0024] The second slide groove is fixedly connected to the base, and the second slide rod is fixedly connected to the second rotating pair; the shape of the opening end of the second slide groove is adapted to the shape of the second slide rod, and the second slide groove is sleeved on the second slide rod.

[0025] In one embodiment, the second rotation pair includes a fourth U-shaped member and a fourth rotation rod rotatably connected to the fourth U-shaped member;

[0026] The fourth U-shaped member is fixedly connected to the second movable pair; the upper end of the fourth U-shaped member is provided with a seventh through hole and an eighth through hole, and the seventh through hole is arranged opposite to the eighth through hole; the fourth rotating rod is movably connected to the seventh through hole and the eighth through hole; the fourth rotating rod is fixedly connected to the ball pair; the rotation direction of the fourth rotating rod is the rotation direction of the second rotating pair.

[0027] In one embodiment, the ball pair includes a fixed seat and a movable member movably connected to the fixed seat;

[0028] The movable member comprises a spherical portion, and a connecting rod fixedly connected to the spherical portion, and the other end of the connecting rod is fixedly connected to the second rotating pair;

[0029] The bottom of the fixing seat is fixedly connected to the moving platform, and the fixing seat is a hemispherical groove body; the hemispherical groove body is movably connected to the spherical part.

[0030] In one embodiment, the area of ​​the moving platform is smaller than the area of ​​the base.

[0031] In one embodiment, the third branch chain is disposed on a perpendicular bisector of a line segment having the bottoms of the first branch chain and the second branch chain as endpoints.

[0032] Beneficial effects of the present invention: The present invention sets the first moving pair as the intermediate rod and the second moving pair directly connected to the base as driving pairs, so that the parallel mechanism contains both an inner driving pair and an outer driving pair. Since the inner driving mode can effectively increase the working space of the parallel mechanism, and the driving pair is directly connected to the base in the outer driving mode, the ability of the parallel mechanism to resist elastic deformation when subjected to force can be effectively improved. Therefore, the present invention can effectively improve the overall rigidity of the parallel mechanism while maintaining the working space of the parallel mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 It is a structural schematic diagram of a parallel mechanism with inner and outer pairs jointly driven provided in an embodiment of the present invention.

[0035] Figure 2 It is a schematic diagram of the structure of the first branch chain / second branch chain provided in an embodiment of the present invention.

[0036] Figure 3 Schematic diagram of the structure of the third branch chain provided in an embodiment of the present invention.

[0037] Description of Figure Numbers:

[0038] Base 1 First moving pair 15 Dynamic Platform 2 The first rotating pair 16 The first branch chain 3 Second chute 17 Second branch chain 4 Second Slider 18 The third branch 5 Fourth U-shaped piece 19 First U-shaped member 6 Fourth rotating lever 20 First rotating lever 7 Connecting rod 21 Second rotating lever 8 Spherical part 22 Second U-shaped member 9 Fixed seat 23 First chute 10 The second moving pair 24 First Slider 11 The second rotating pair 25 The third rotating lever 12 Active parts 26 The third U-shaped piece 13 Ball Vice 27 Universal vice 14 DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the present invention clearer and more specific, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0040] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, and back), such directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0041] In recent years, hybrid machine tools and hybrid robots have been widely used in high-end manufacturing industries such as the aerospace industry, the automotive industry, and optical engineering to solve tasks such as polishing, spraying, drilling, assembly, and stir friction welding that require high equipment accuracy and rigidity. The main body of hybrid machine tools and hybrid robots is a parallel mechanism, which can be defined as a mechanism in which the upper and lower platforms are connected by two or more branches and driven in parallel. Among them, the three-degree-of-freedom one-horizontal and two-rotational parallel mechanism is widely used because of its advantages such as large ratio of workspace to fuselage area, flexible posture space, and excellent dynamic characteristics.

[0042] At present, the more typical three-degree-of-freedom one-horizontal and two-rotation parallel mechanisms include the 3UPS-UP parallel mechanism developed by PKM Tricept of Spain, the 2UPR-SPR parallel mechanism developed by Exechon of Sweden, the 2UPR-RPS parallel mechanism developed by Yanshan University, the 2UPR-RPU parallel mechanism developed by Zhejiang Sci-Tech University, and the 2UPR-RRU parallel mechanism developed by Tongji University (the letters R, P, U, and S in the parallel mechanism refer to the rotation pair, the translation pair, the universal pair, and the ball pair, respectively). However, in the above three-degree-of-freedom one-horizontal and two-rotation parallel main structure, the translation drive pair is located in the middle rod, that is, an internal drive method is adopted. This structural design and drive method make the parallel mechanism have a larger working space and easy to control, but it reduces the stiffness of the mechanism to a certain extent.

[0043] In order to solve the above problems in the prior art, this embodiment provides a parallel mechanism driven by inner and outer pairs. Figure 1 As shown, the parallel mechanism driven by the inner and outer pairs comprises: a base 1, and a moving platform 2 arranged opposite to the base 1. The base 1 plays a stabilizing and firming role for the parallel structure as a whole. The moving platform 2 is a motion platform, which performs relative motion or posture change relative to the base 1. A first branch chain 3 and a second branch chain 4 are arranged between the base 1 and the moving platform 2. That is, the moving platform 2 is equivalent to being supported by multiple branches at the same time, so that the parallel mechanism as a whole has the advantages of stable structure and strong bearing capacity.

[0044] In this embodiment, in order to realize the movement of the moving platform 2, the first branch chain 3 and the second branch chain 4 are configured in the form of multiple kinematic pairs connected in series, so that the moving platform 2 can realize different posture changes with the activities of different kinematic pairs on the branches. Simply put, a kinematic pair is a moving assembly composed of two or more components, and the components are in direct contact and can be movably connected. According to the relative motion properties between the two components that constitute the kinematic pair, it can be divided into a moving pair, a rotating pair, a universal pair and a ball pair. Among them, a moving pair refers to a kinematic pair that can only move relative to each other between the two components that constitute the kinematic pair; a rotating pair refers to a kinematic pair that can only rotate relative to each other between the two components that constitute the kinematic pair; and a universal pair refers to a kinematic pair that can rotate relative to each other in two directions between the two components that constitute the kinematic pair. Since different kinematic pairs have different motion forms, after combining them, different kinematic pairs will form constraints on each other during movement, thereby jointly constituting the posture change of the moving platform 2.

[0045] like Figure 2As shown, the first branch chain 3 and the second branch chain 4 have the same structure, both including a universal joint 14, a first movable joint 15 and a first rotating joint 16; the universal joint 14 is connected to the base 1; the first rotating joint 16 is connected to the moving platform 2; the first movable joint 15 is connected to both the universal joint 14 and the first rotating joint 16.

[0046] Specifically, since the universal joint 14 is connected to the base 1, when the universal joint 14 rotates, the entire chain can be driven to rotate from the bottom of the branch chain, thereby realizing the rotation of the moving platform 2. The first rotating joint 16 is connected to the moving platform 2, so when the other moving joints of the branch chain remain stationary, it can also drive the moving platform 2 to move when it rotates alone. The universal joint 14 and the first rotating joint 16 are connected by the first moving joint 15, and the first moving joint 15 can drive the moving platform 2 to translate, thereby causing the moving platform 2 to move closer to or away from the base 1.

[0047] In order to enhance the load-bearing capacity and stability of the moving platform 2, Figure 1 As shown, a third branch chain 5 is further provided between the first branch chain 3 and the second branch chain 4. Figure 3 As shown, the third branch chain 5 includes a second moving pair 24, a second rotating pair 25 and a ball pair 27. The second moving pair 24 is connected to the base 1, the ball pair 27 is connected to the moving platform 2, and the second rotating pair 25 is connected to both the ball pair 27 and the second moving pair 24. Specifically, a ball pair refers to a kinematic pair in which two components constituting the kinematic pair can perform relative rotation in any direction. Since the ball pair can achieve rotation in more directions compared to the moving pair, the rotating pair and the universal pair, after the ball pair 27 is connected to the moving platform 2, it does not affect the movement of other kinematic pairs on the first branch chain 3 and the second branch chain 4, thereby effectively avoiding limiting the range of motion of the moving platform 2.

[0048] In addition, in order to improve the rigidity of the parallel mechanism driven by the internal and external pairs, the first moving pair 15 and the second moving pair 24 are set as driving pairs in this embodiment. Specifically, the driving pair refers to a moving pair in which the relative motion law of the two components of the moving pair in the parallel mechanism is known, that is, a moving pair with a driving effect between the two components. The moving pair in the parallel mechanism that is not a driving pair is a driven pair. When the driving pair is an intermediate rod, that is, the driving pair is not directly connected to the base 1, it means that an internal drive method is adopted, which can make the parallel mechanism have a larger working space and easy to control, but reduce the rigidity of the parallel mechanism to a certain extent. When the driving pair is directly connected to the base 1, it means that an external drive method is adopted. Since the driving pair is directly connected to the base 1 in the external drive method, it can effectively improve the ability of the parallel mechanism to resist elastic deformation when subjected to force, which is equivalent to improving the rigidity of the parallel mechanism. In this embodiment, the first movable pair 15 serving as the intermediate rod and the second movable pair 24 directly connected to the base 1 are both set as driving pairs, and the driving motor is connected to the screw guide rail to realize the translational movement of the first movable pair 15 and the second movable pair 24, so that the parallel mechanism contains both an inner driving pair and an outer driving pair. Therefore, while having a larger working space, the overall stiffness of the parallel mechanism can also be effectively improved.

[0049] Since the three branches supporting the movable platform 2 all contain rotatable kinematic pairs, it is necessary to reasonably set their rotation directions so that they can cooperate with each other to realize the rotation of the movable platform 2 relative to the base 1. In one implementation, the rotation direction of the universal joint 14 includes a first rotation direction and a second rotation direction perpendicular to the first rotation direction, the rotation direction of the first rotation pair 16 is parallel to the second rotation direction, and the rotation direction of the second rotation pair 25 is parallel to the first rotation direction.

[0050] Specifically, the movement directions of all the kinematic pairs in the parallel mechanism jointly construct the range of motion and the posture transformation mode of the parallel mechanism. Therefore, in order to reasonably set the movement direction of each kinematic pair, in this embodiment, the rotation direction of the first rotation pair 16 and the second rotation pair 25 can be set based on the rotation direction of the universal joint 14. Figure 2 As shown, Figure 2Taking the coordinate system of as an example, the rotation direction of the universal joint 14 includes a first rotation direction and a second rotation direction perpendicular to the first rotation direction. The first rotation direction is the direction of rotation around the Y axis, and the second rotation direction is the direction of rotation around the X axis. In order to cooperate with the rotation of the universal joint 14, the rotation direction of the first rotation joint 16 is set to be parallel to the second rotation direction, and the rotation direction of the second rotation joint 25 is parallel to the first rotation direction. In addition, with the cooperation of the ball joint 27, the moving platform 2 finally includes two rotation directions, and one of the rotation directions is parallel to the first rotation direction, and the other rotation direction is parallel to the second rotation direction. That is, the moving platform 2 can rotate in two directions, so that the parallel mechanism driven by the inner and outer joints has two rotational degrees of freedom.

[0051] In addition, when the first moving pair 15 and the second moving pair 24 are linearly driven, the moving platform 2 can also be translated. Therefore, the parallel mechanism driven by the inner and outer pairs also includes a translational degree of freedom. It can be understood that although the moving direction of the first moving pair 15 is parallel to the moving direction of the second moving pair 24, the moving direction of the first moving pair 15 and the moving direction of the second moving pair 24 can be in the same direction or in different directions, and the moving displacement of the first moving pair 15 and the moving displacement of the second moving pair 24 can also be equal or unequal. For example, when the first moving pair 15 and the second moving pair 24 both move 20 centimeters in a direction perpendicular to the plane of the base 1 and away from the plane of the base 1, it means that the moving platform 2 makes a translational motion relative to the base 1, and then the first moving pair 15 moves 10 centimeters in a direction perpendicular to the plane of the base 1 and close to the plane of the base 1, and at the same time, the second moving pair 24 moves 5 centimeters in a direction perpendicular to the plane of the base 1 and away from the plane of the base 1, and with the cooperation of the driven pairs such as the universal joint 14, the second rotating pair 25, and the ball pair 27, the moving platform 2 can be rotated in a direction parallel to the first rotation direction.

[0052] In one implementation, the first moving pair 15 can be divided into a left moving pair on the first branch chain 3 and a right moving pair on the second branch chain 4. Similarly, the moving direction of the left moving pair and the moving direction of the right moving pair can be the same direction or different directions, and the moving displacement of the left moving pair and the moving displacement of the right moving pair can also be equal or unequal. For example, when the left moving pair, the right moving pair and the second moving pair 24 all move 20 centimeters in a direction perpendicular to the plane of the base 1 and away from the plane of the base 1, it means that the moving platform 2 makes a translational motion relative to the base 1, and then the left moving pair moves 10 centimeters in a direction perpendicular to the plane of the base 1 and close to the plane of the base 1, and at the same time, the right moving pair moves 5 centimeters in a direction perpendicular to the plane of the base 1 and away from the plane of the base 1, and the second moving pair 24 is adaptively driven according to the movement of the left moving pair and the right moving pair, and with the cooperation of the driven pairs such as the universal joint 14, the second rotating pair 25, and the ball pair 27, the moving platform 2 can be rotated in a direction parallel to the second rotation direction.

[0053] In one implementation, Figure 2 As shown, the universal joint 14 includes a first U-shaped member 6 and a second U-shaped member 9 movably connected to the first U-shaped member 6. The first U-shaped member 6 is fixedly connected to the base 1, and the upper end of the first U-shaped member 6 is provided with a first through hole, a second through hole, and a first rotating rod 7 movably connected to the first through hole and the second through hole, and the first through hole is arranged opposite to the second through hole. The second U-shaped member 9 is fixedly connected to the first movable joint 15, and the upper end of the second U-shaped member 9 is provided with a third through hole, a fourth through hole, and a second rotating rod 8 movably connected to the third through hole and the fourth through hole, and the third through hole is arranged opposite to the fourth through hole. The first rotating rod 7 is perpendicular to and fixedly connected to the second rotating rod 8. When the first rotating rod 7 rotates relative to the first through hole and the second through hole, the universal joint is rotated in the first rotation direction. When the second rotating rod 8 rotates relative to the third through hole and the fourth through hole, the universal joint is rotated in the second rotation direction.

[0054] Specifically, Figure 2As shown, the bottom of the first U-shaped member 6 is fixedly connected to the base 1, that is, the first U-shaped member 6 does not have a rotation function in the universal joint 14, but is fixedly connected to the base 1. The upper end of the first U-shaped member 6 is provided with a first through hole, a second through hole, and a first rotating rod 7 movably connected to the first through hole and the second through hole, that is, the first rotating rod 7 can rotate in the first through hole and the second through hole. Since the first rotating rod 7 and the second rotating rod 8 are vertically and fixedly connected, and the second rotating rod 8 and the second U-shaped member 9 are connected, when the first rotating rod 7 rotates in the first through hole and the second through hole, it is equivalent to the second U-shaped member rotating with the first rotating rod 7 as the rotation axis, thereby realizing the rotation of the universal joint 14 in the first rotation direction. The upper end of the second U-shaped member 9 is provided with a third through hole, a fourth through hole, and a second rotating rod 8 movably connected to the third through hole and the fourth through hole. Therefore, the second U-shaped member 9 can also rotate with the second rotating rod 8 as the rotating axis, thereby realizing the rotation of the universal joint in the second rotating direction.

[0055] In one implementation, Figure 2 As shown, the first moving pair 15 includes a first slide slot 10 and a first slide bar 11 slidably connected to the first slide slot 10. The first slide slot 10 is fixedly connected to the universal joint 14, and the first slide bar 11 is fixedly connected to the first rotating pair 16. The shape of the opening end of the first slide slot 10 is adapted to the shape of the first slide bar 11, and the first slide slot 10 is sleeved on the first slide bar 11.

[0056] Specifically, the specific forms of the two components constituting the moving pair can be various. In this embodiment, the first sliding groove 10 and the first sliding rod 11 are used to constitute the first moving pair 15, wherein the bottom of the first sliding groove 10 is fixedly connected to the universal joint 14, the open end of the first sliding groove 10 is connected to the first sliding rod 11, and the other end of the first sliding rod 11 is fixedly connected to the first rotating pair 16. The shape of the groove body of the first sliding groove 10 is adapted to the shape of the first sliding rod 11, thereby limiting the motion trajectory of the first sliding rod 11, so that it can only move linearly along the inner wall of the first sliding groove 10, thereby effectively improving the accuracy of each action of the parallel mechanism driven by the inner and outer pairs. When the first moving pair 15 is required to have a higher motion sensitivity, that is, when it is desired to reduce the friction in the guide rail, in one implementation, a ball bearing can be set in the first sliding groove 10, so as to convert the sliding friction between the first sliding groove 10 and the first sliding rod 11 into rolling friction, thereby greatly reducing the friction resistance between the first sliding groove 10 and the first sliding rod 11.

[0057] In one implementation, Figure 2 As shown, the first rotating pair 16 includes a third U-shaped member 13, a third rotating rod 12 rotatably connected to the third U-shaped member 13, and the third U-shaped member 13 is connected to the moving platform 2. The upper end of the third U-shaped member 13 is provided with a fifth through hole and a sixth through hole, and the fifth through hole is arranged opposite to the sixth through hole. The third rotating rod 12 is movably connected to the fifth through hole and the sixth through hole, and the third rotating rod 12 is vertically and fixedly connected to the first moving pair 15. The rotation direction of the third rotating rod 12 is the rotation direction of the first rotating pair 16.

[0058] Specifically, when the third rotating rod 12 rotates relative to the fifth through hole and the sixth through hole, it is equivalent to that the third U-shaped member 13 rotates with the third rotating rod 12 as the rotation axis. Since the rotation direction of the third rotating rod 12 is the rotation direction of the first rotating pair 16, and the rotation direction of the first rotating pair 16 is parallel to the second rotation direction, the third rotating rod 12 should be set to be parallel to the second rotating rod 8 in the initial form of the parallel mechanism driven by the inner and outer pairs. Since the bottom of the third U-shaped member 13 is fixedly connected to the moving platform 2, when the third U-shaped member 13 rotates with the third rotating rod 12 as the rotation axis, the moving platform 2 also rotates accordingly.

[0059] In order to achieve a stable connection between the third rotating rod 12 and the first moving pair 15, in one implementation, a circular ring structure is provided at one end of the first sliding rod 11, and the circular ring structure is used to stably sleeve the first sliding rod 11 on the middle part of the third rotating rod 12. Specifically, the inner circumference of the circular ring structure is fixedly connected to the third rotating rod 12, and the outer circumference of the circular ring structure is fixedly connected to one end of the first sliding rod 11, thereby achieving a stable connection between the third rotating rod 12 and the first sliding rod 11.

[0060] In order to improve the structural strength of the first branch chain 3 / the second branch chain 4, in one implementation, the second U-shaped member 9 and the first slide slot 10 can be set as an integrated structure, and the first slide bar 11 and the third rotating bar 12 can be set as an integrated structure. This prevents the two components fixed to each other from being relatively displaced when the entire mechanism moves due to insufficient stability of the fixation, thereby reducing the movement accuracy of the entire mechanism.

[0061] In one implementation, Figure 3As shown, the second movable pair 24 includes a second slide groove 17, and a second slide rod 18 slidably connected to the second slide groove 17; the second slide groove 17 is fixedly connected to the base 1, and the second slide rod 18 is fixedly connected to the second rotating pair 25; the shape of the open end of the second slide groove 17 is adapted to the shape of the second slide rod 18, and the second slide groove 17 is sleeved on the second slide rod 18.

[0062] Specifically, the bottom of the second chute 17 is fixedly connected to the base 1, the open end of the second chute 17 is connected to the second slide bar 18, and the other end of the second slide bar 18 is fixedly connected to the second rotating pair 25. The shape of the second chute 17 is adapted to the shape of the second slide bar 18, thereby limiting the movement trajectory of the second slide bar 18, so that it can only move linearly along the inner wall of the second chute 17, thereby effectively improving the accuracy of each action of the parallel mechanism driven by the inner and outer pairs. It can be understood that, like the first mobile pair 15, when it is necessary to reduce the friction resistance of the first mobile pair 15, the sliding friction between the second chute 17 and the second slide bar 18 can also be converted into rolling friction.

[0063] In one implementation, Figure 3 As shown, the second rotation pair 25 includes a fourth U-shaped member 19 and a fourth rotation rod 20 rotatably connected to the fourth U-shaped member 19. The fourth U-shaped member 19 is fixedly connected to the second movable pair 24; the upper end of the fourth U-shaped member 19 is provided with a seventh through hole and an eighth through hole, and the seventh through hole is arranged opposite to the eighth through hole. The fourth rotation rod 20 is movably connected to the seventh through hole and the eighth through hole; the fourth rotation rod 20 is fixedly connected to the ball pair 27. The rotation direction of the fourth rotation rod 20 is the rotation direction of the second rotation pair 25.

[0064] Specifically, when the fourth rotating rod 20 rotates relative to the seventh through hole and the eighth through hole, it is equivalent to the fourth U-shaped member 19 rotating with the fourth rotating rod 20 as the rotation axis. Since the rotation direction of the fourth rotating rod 20 is the rotation direction of the second rotating pair 25, and the rotation direction of the second rotating pair 25 is parallel to the first rotation direction, the fourth rotating rod 20 should be set to be parallel to the first rotating rod 7 in the initial form of the parallel mechanism driven by the inner and outer pairs.

[0065] In one implementation, Figure 3As shown, the ball pair 27 includes a fixed seat 23 and a movable part 26 movably connected to the fixed seat 23; the movable part 26 includes a spherical portion 22, and a connecting rod 21 fixedly connected to the spherical portion 22, and the other end of the connecting rod 21 is fixedly connected to the second rotating pair 25; the bottom of the fixed seat 23 is fixedly connected to the moving platform 2, and the fixed seat 23 is a hemispherical groove body; the hemispherical groove body is movably connected to the spherical portion 22.

[0066] Specifically, when the ball pair 27 rotates, it is equivalent to relative movement between the fixed seat 23 and the movable member 26. Since the ball pair 27 can rotate in multiple directions, it can well cooperate with the movement direction of other driven members to move.

[0067] In order to achieve a stable connection between the fourth rotating rod 20 and the ball joint 27, in one implementation, a circular ring structure is provided at one end of the connecting rod 21, and the circular ring structure is used to stably sleeve the movable member 26 on the middle part of the fourth rotating rod 20. Specifically, the inner circumference of the circular ring structure is fixedly connected to the fourth rotating rod 20, and the outer circumference of the circular ring structure is fixedly connected to one end of the connecting rod 21, thereby achieving a stable connection between the fourth rotating rod 20 and the ball joint 27.

[0068] In order to improve the overall structural strength of the third branch chain 5, in one implementation, the movable member 26 and the fourth rotating rod 20 are configured as an integrated structure, and the fourth U-shaped member 19 and the second sliding rod 18 are configured as an integrated structure. The configuration of the integrated structure is not only conducive to improving the transmission efficiency, but also conducive to simplifying the installation steps during installation.

[0069] In order to improve the stability of the parallel mechanism driven by the internal and external pairs, in one implementation, the area of ​​the moving plane is set to be smaller than the area of ​​the base 1. The stability of an object is related to the center of gravity of the object and the bottom area of ​​the support surface. When the center of gravity remains unchanged, the larger the bottom area of ​​the support surface, the more stable it is. Since the base 1 plays a role of stable support in the parallel mechanism driven by the internal and external pairs, when the area of ​​the base 1 is larger than the area of ​​the moving plane, the parallel mechanism driven by the internal and external pairs is in a relatively stable state. According to the user's use requirements, the moving plane and the base 1 can be set to various shapes such as circle, triangle, trapezoid, etc. In one implementation, the shape of the moving plane and the base 1 is set to an isosceles trapezoid and is set in the same direction. In order to maintain the stability of the parallel mechanism driven by the internal and external pairs, the first branch chain 3 and the second branch chain 4 are set at the two ends of the lower bottom of the isosceles trapezoid, and the third branch chain 5 is set at the upper bottom and is located on the perpendicular midline of the line segment with the bottoms of the first branch chain 3 and the second branch chain 4 as endpoints. As a result, the first branch chain 3, the second branch chain 4 and the third branch chain 5 are distributed in a "T" shape, so as to more stably support the movement of the moving plane.

[0070] In summary, the present invention discloses a parallel mechanism driven by inner and outer pairs, the parallel mechanism driven by inner and outer pairs comprises: a base, a moving platform, a first branch chain, a second branch chain and a third branch chain; the first branch chain has the same structure as the second branch chain, both comprising a universal pair connected to the base, a first rotating pair connected to the moving platform, and a first moving pair connected to both the universal pair and the first rotating pair; the third branch chain comprises a second moving pair connected to the base, a ball pair connected to the moving platform, and a second rotating pair connected to both the ball pair and the second moving pair; the first moving pair and the second moving pair are driving pairs. The present invention effectively improves the overall stiffness of the parallel mechanism by setting the first moving pair, which serves as an intermediate rod, and the second moving pair, which is directly connected to the base, as driving pairs.

[0071] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A parallel mechanism with internal and external pairs jointly driven, It is characterized in that The parallel mechanism driven by the inner and outer pairs comprises: a base, a moving platform arranged opposite to the base, a first branch chain, a second branch chain and a third branch chain connecting the base and the moving platform; the third branch chain is arranged between the first branch chain and the second branch chain; The first branch chain has the same structure as the second branch chain, and both include a universal joint, a first moving joint, and a first rotating joint; the universal joint is connected to the base; the first rotating joint is connected to the moving platform; the first moving joint is connected to both the universal joint and the first rotating joint; The third branch chain includes a second moving pair, a second rotating pair and a ball pair; the second moving pair is connected to the base; the ball pair is connected to the moving platform; the second rotating pair is connected to both the ball pair and the second moving pair; The first moving pair and the second moving pair are driving pairs; The first moving pair comprises a first sliding groove and a first sliding rod slidably connected to the first sliding groove; The first slide groove is fixedly connected to the universal joint, and the first slide bar is fixedly connected to the first rotational joint; the shape of the opening end of the first slide groove is adapted to the shape of the first slide bar, and the first slide groove is sleeved on the first slide bar; A ball is arranged in the first slide groove; The shape of the moving platform and the base is set to be an isosceles trapezoid and are arranged in the same direction; The first branch chain and the second branch chain are arranged at two ends of the lower base of the isosceles trapezoid, and the third branch chain is arranged at the upper base and is located on the perpendicular bisector of the line segment with the bottoms of the first branch chain and the second branch chain as endpoints.

2. The parallel mechanism with inner and outer pairs jointly driven according to claim 1, It is characterized in that The rotation direction of the universal joint includes a first rotation direction and a second rotation direction perpendicular to the first rotation direction; The rotation direction of the first rotation pair is parallel to the second rotation direction; The rotation direction of the second rotation pair is parallel to the first rotation direction.

3. The parallel mechanism with inner and outer pairs jointly driven according to claim 2, It is characterized in that The universal joint comprises a first U-shaped member and a second U-shaped member movably connected to the first U-shaped member; The first U-shaped member is fixedly connected to the base, and the upper end of the first U-shaped member is provided with a first through hole, a second through hole, and a first rotating rod movably connected to the first through hole and the second through hole, and the first through hole is arranged opposite to the second through hole; The second U-shaped member is fixedly connected to the first moving pair; the upper end of the second U-shaped member is provided with a third through hole, a fourth through hole, and a second rotating rod movably connected to the third through hole and the fourth through hole, and the third through hole is arranged opposite to the fourth through hole; the first rotating rod is perpendicular to and fixedly connected to the second rotating rod; When the first rotating rod rotates relative to the first through hole and the second through hole, the universal joint rotates in the first rotating direction; When the second rotating rod rotates relative to the third through hole and the fourth through hole, the universal joint is rotated in the second rotating direction.

4. The parallel mechanism with inner and outer pairs jointly driven according to claim 1, It is characterized in that The first rotating pair comprises a third U-shaped member and a third rotating rod rotatably connected to the third U-shaped member; The third U-shaped member is connected to the moving platform, and a fifth through hole and a sixth through hole are provided at the upper end of the third U-shaped member, and the fifth through hole and the sixth through hole are arranged opposite to each other; the third rotating rod is movably connected to the fifth through hole and the sixth through hole; the third rotating rod is perpendicular to and fixedly connected to the first moving pair; the rotation direction of the third rotating rod is the rotation direction of the first rotating pair.

5. The parallel mechanism with inner and outer pairs jointly driven according to claim 2, It is characterized in that The second moving pair comprises a second slide groove and a second slide rod slidably connected to the second slide groove; The second slide groove is fixedly connected to the base, and the second slide rod is fixedly connected to the second rotating pair; the shape of the opening end of the second slide groove is adapted to the shape of the second slide rod, and the second slide groove is sleeved on the second slide rod.

6. The parallel mechanism with inner and outer pairs jointly driven according to claim 5, It is characterized in that The second rotating pair comprises a fourth U-shaped member and a fourth rotating rod rotatably connected to the fourth U-shaped member; The fourth U-shaped member is fixedly connected to the second movable pair; the upper end of the fourth U-shaped member is provided with a seventh through hole and an eighth through hole, and the seventh through hole is arranged opposite to the eighth through hole; the fourth rotating rod is movably connected to the seventh through hole and the eighth through hole; the fourth rotating rod is fixedly connected to the ball pair; the rotation direction of the fourth rotating rod is the rotation direction of the second rotating pair.

7. The parallel mechanism with inner and outer pairs jointly driven according to claim 5, It is characterized in that The ball pair includes a fixed seat and a movable part movably connected to the fixed seat; The movable member comprises a spherical portion, and a connecting rod fixedly connected to the spherical portion, and the other end of the connecting rod is fixedly connected to the second rotating pair; The bottom of the fixing seat is fixedly connected to the moving platform, and the fixing seat is a hemispherical groove body; the hemispherical groove body is movably connected to the spherical part.

8. The parallel mechanism with inner and outer pairs jointly driven according to claim 1, It is characterized in that The area of ​​the moving platform is smaller than the area of ​​the base.

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