Rotor balance type frameless motor and robot

Abstract

The rotor balance type frameless motor comprises a connector, a supporting bottom plate, a supporting structure, a stator and a rotor, the supporting structure is used in cooperation with the upper surface of the supporting bottom plate, and the stator is fixedly arranged on the inner side of the supporting structure; the rotor is located at the axis of the supporting structure. A connecting column is arranged at one end of the rotor. A balance adjusting assembly for adjusting the gravity center of the rotor is arranged on the outer arc surface of the rotor; the upper surface of the connector is provided with a size adjusting assembly used for installing rotors of different sizes. The height of a set of adjusting clamping plates and fixing clamping plates is adjusted through the height adjusting module, so that it is guaranteed that rotors with different heights can be installed through the adjusting clamping plates and the fixing clamping plates, and the distances between the two sets of adjusting clamping plates and the corresponding fixing clamping plates are adjusted through the diameter adjusting module, so that the rotors with different diameters are installed; therefore, the frameless motor can be suitable for rotation of motors of various specifications and dimensions, and the overall adjustability of the motor is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of motors, and in particular relates to a rotor-balanced frameless motor and a robot. Background Art

[0002] In modern industrial production and advanced robotics applications, motors are key power output components, and their performance directly affects the operating stability and work efficiency of the entire equipment or system. Due to their unique structural design, frameless motors have been widely used in many fields that have strict requirements on space compactness, dynamic response performance, and high-precision control, such as humanoid robots, medical equipment, and precision industrial automation equipment.

[0003] However, the existing frameless motors generally face the problem of difficulty in effectively ensuring the balance of the motor rotor during actual operation. As the core component of the motor to achieve energy conversion and power output, the motor rotor will cause a series of serious problems when it rotates at high speed if its mass distribution is uneven or it is disturbed by external factors, resulting in a shift in the center of gravity. At the same time, with the continuous advancement of science and technology and the increasing diversification of application needs, different industries and fields have put forward more extensive and personalized requirements for the specifications and performance parameters of frameless motors. In the design and manufacturing process, the existing frameless motors are often customized for specific application scenarios and specification requirements, which leads to obvious deficiencies in versatility and adjustability. When motor rotors of different diameters and lengths are required in the same equipment or system to meet different work tasks or adapt to different installation spaces, the existing frameless motors are usually not directly adaptable, and the entire motor structure and even the equipment system need to be redesigned and modified on a large scale, which not only consumes a lot of time, manpower and material resources, but also seriously affects the product's R&D cycle and market competitiveness. To sum up, how to develop a new frameless motor that can effectively solve the problem of motor rotor balance, while having good versatility and adjustability, and can easily and quickly adapt to the installation requirements of motor rotors of various specifications and sizes has become a key issue that needs to be urgently solved in the current field of motor technology. Summary of the invention

[0004] The object of the present invention is to provide a rotor balanced frameless motor and a robot, wherein the height of a group of adjusting plates and a fixed plate is adjusted by a height adjustment module, thereby ensuring that the adjusting plates and the fixed plates can install rotors of different heights, and the distance between the two groups of adjusting plates and the corresponding fixed plates is adjusted by a diameter adjustment module, thereby installing rotors of different diameters, thereby solving the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention adopts the following technical solutions: A rotor-balanced frameless motor, comprising a connector, a support base plate, a support structure, a stator and a rotor. The support structure is used in cooperation with the upper surface of the support base plate, and the stator is fixedly arranged inside the support structure; The rotor is located at the axis center of the support structure, and a connecting column is arranged at one end of the rotor; A balance adjustment assembly for adjusting the center of gravity of the rotor is arranged on the outer arc surface of the rotor; a size adjustment assembly for installing rotors of different sizes is arranged on the upper surface of the connector; The size adjustment assembly includes adjusting clamping plates, fixed clamping plates, a height adjustment module for adjusting the heights of the adjusting clamping plates and the fixed clamping plates, and a diameter adjustment module for adjusting the distance between the adjusting clamping plates and the fixed clamping plates; There are two groups of the adjusting clamping plates and the fixed clamping plates. The two groups of the adjusting clamping plates and the fixed clamping plates are located on both sides of the rotor, and mounting grooves are formed on the sides of the adjusting clamping plates and the fixed clamping plates close to the rotor.

[0006] Preferably, the height adjustment module includes a limit frame, a connecting plate, a lead screw, a moving block and a connecting structure. The limit frame is fixedly arranged on the upper surface of the connector. The connecting plate is slidably arranged on one side of the limit frame through the moving block. The fixed clamping plate is bolted to the side of the connecting plate away from the limit frame, and the moving block is threadedly sleeved on the outer arc surface of the lead screw. The fixed clamping plate is connected to the corresponding adjusting clamping plate through the connecting structure.

[0007] Preferably, the moving block is arranged as a convex block. A moving groove corresponding to the moving block is formed on the side of the limit frame close to the rotor, and the lead screw is rotatably arranged inside the moving groove.

[0008] Preferably, the diameter adjustment module includes a connecting sleeve plate, a connecting inner plate and an electric push rod. The connecting inner plate is slidably arranged inside the connecting sleeve plate. The bottom end of the electric push rod is fixedly arranged on one side of the support base plate. The working end of the electric push rod is connected to the connecting sleeve plate. The connecting sleeve plate is fixedly connected to one group of adjusting clamping plates, and the connecting inner plate is fixedly connected to the other group of adjusting clamping plates.

[0009] Preferably, the balance adjustment assembly includes a fixed ring, a rotating column and a configuration block. The fixed ring is fixedly sleeved on the outer arc surface of the rotor. The fixed ring is arranged inside the stator. There are several groups of the rotating columns and the configuration blocks. The several groups of the configuration blocks are slidably arranged inside the fixed ring, and the configuration blocks are threadedly sleeved on the outer arc surfaces of the corresponding rotating columns.

[0010] Preferably, the configuration block is arranged as a convex block, and several groups of adjustment grooves corresponding to the configuration blocks are formed on the outer arc surface of the fixed ring. The several groups of the rotating columns are rotatably arranged inside the corresponding adjustment grooves.

[0011] Preferably, two groups of limiting rings are symmetrically arranged on the outer arc surfaces of several groups of the rotating columns. Several groups of the rotating columns are rotatably arranged inside the fixed ring through the corresponding limiting rings, and first limiting grooves corresponding to the limiting rings are formed inside the fixed ring.

[0012] Preferably, the top end of the lead screw penetrates through the limiting frame, and the top ends of several groups of the rotating columns penetrate through the fixed ring. Operation holes are formed at the top ends of both the limiting frame and the rotating columns.

[0013] Preferably, a limiting block is fixedly arranged on the lower surface of the connecting inner plate. A telescopic groove corresponding to the connecting inner plate is formed inside the connecting sleeve plate. A second limiting groove corresponding to the limiting block is formed on the upper surface of the connecting sleeve plate, and the telescopic groove and the second limiting groove are communicated.

[0014] The present invention also provides a robot, including a rotor-balanced frameless motor used above.

[0015] The advantages and beneficial effects of the present invention compared with the prior art are as follows: For the rotor-balanced frameless motor and the robot of the present invention, the heights of a group of adjusting clamping plates and fixed clamping plates are adjusted through the height adjustment module, so as to ensure that the adjusting clamping plates and the fixed clamping plates can install rotors with different heights. And the distance between two groups of adjusting clamping plates and the corresponding fixed clamping plates is adjusted through the diameter adjustment module, so as to install rotors with different diameters, so that the frameless motor can be applicable to the rotation of motors of various specifications and sizes, greatly improving the overall adjustability of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic diagram of the overall structure of the frameless motor of the present invention; Figure 2 is an exploded view of the frameless motor of the present invention; Figure 3 is a cross-sectional view of the balance adjustment assembly of the present invention; Figure 4 is of the present invention Figure 2 enlarged view of the structure at A in; Figure 5 is of the present invention Figure 2 enlarged view of the structure at B in; Figure 6 is of the present invention Figure 3 enlarged view of the structure at C in; Figure 7 is a schematic diagram of the structure of the robot of the present invention.

[0017] In the figure: 1. Connector; 2. Support base plate; 3. Support structure; 4. Connecting sleeve plate; 5. Connecting inner plate; 6. Stator; 7. Fixed ring; 8. Adjusting clamping plate; 9. Connecting column; 10. Fixed clamping plate; 11. Limiting frame; 12. Connecting plate; 13. Lead screw; 14. Rotor; 15. Moving block; 16. Moving groove; 17. Electric push rod; 18. First limiting groove; 19. Rotating column; 20. Configuration block; 21. Limiting ring; 22. Adjusting groove; 23. Limiting block; 24. Telescopic groove; 25. Second limiting groove; 26. Robot; 27. Joint. Detailed implementation manner

[0018] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. The preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present invention more thorough and comprehensive.

[0019] The present invention provides a Figures 1 - 6 rotor-balanced frameless motor as described above, including a connector 1, a support base plate 2, a support structure 3, a stator 6 and a rotor 14. The support structure 3 is used in cooperation with the upper surface of the support base plate 2, and the stator 6 is fixedly arranged inside the support structure 3; the rotor 14 is used to generate a rotational movement under the influence of the magnetic field generated by the stator 6, and the rotor 14 is located at the axis center of the support structure 3. A connecting column 9 is arranged at one end of the rotor 14; the connector 1 and the support base plate 2 are used to connect and supply power to the stator 6, and the connecting column 9 is arranged to connect the joint of the robot.

[0020] Preferably, a size adjustment component for installing rotors 14 of different sizes is arranged on the upper surface of the connector 1; the size adjustment component includes an adjusting clamping plate 8, a fixed clamping plate 10, a height adjustment module for adjusting the height of the adjusting clamping plate 8 and the fixed clamping plate 10, and a diameter adjustment module for adjusting the distance between the adjusting clamping plate 8 and the fixed clamping plate 10; two groups of the adjusting clamping plate 8 and the fixed clamping plate 10 are arranged, and the two groups of the adjusting clamping plate 8 and the fixed clamping plate 10 are located on both sides of the rotor 14. Installation grooves are opened on the sides of the adjusting clamping plate 8 and the fixed clamping plate 10 close to the rotor 14. One group of the adjusting clamping plate 8 and the fixed clamping plate 10 are located on both sides above the rotor 14, and the other group of the adjusting clamping plate 8 and the fixed clamping plate 10 are located on both sides below the rotor 14. The fixed clamping plate 10 located below is fixedly arranged on one side of the support base plate 2. Through the cooperation of the installation grooves on the sides of the adjusting clamping plate 8 and the fixed clamping plate 10, the technical effect of installing rotors 14 of different sizes is achieved, and the technical problem of needing to produce corresponding support structures when replacing rotors 14 of different sizes is solved.

[0021] It should be noted that the height adjustment module includes a limit frame 11, a connecting plate 12, a lead screw 13, a moving block 15 and a connecting structure.

[0022] Among them, the limit frame 11 is fixedly arranged on the upper surface of the connector 1, the connecting plate 12 is slidably arranged on one side of the limit frame 11 through the moving block 15, the fixed clamping plate 10 is bolted to the side of the connecting plate 12 away from the limit frame 11, and the moving block 15 is threadedly sleeved on the outer arc surface of the lead screw 13. The fixed clamping plate 10 is connected to the corresponding adjusting clamping plate 8 through the connecting structure; the moving block 15 is arranged as a convex block, and a moving groove 16 corresponding to the moving block 15 is opened on one side of the limit frame 11 close to the rotor 14, and the lead screw 13 is rotatably arranged inside the moving groove 16.

[0023] Specifically, by rotating the lead screw 13, the moving block 15 is driven to move up and down inside the moving groove 16, and the moving block 15 is arranged as a convex block, so as to prevent the connecting plate 12 and the moving block 15 from rotating along with the lead screw 13 when moving up and down. When the connecting plate 12 moves up and down, the fixed clamping plate 10 is driven to move up and down, and the fixed clamping plate 10 drives the corresponding adjusting clamping plate 8 to move up and down through the connecting structure. The middle part of the connecting structure is arranged as a telescopic sleeve rod, so as to ensure that the adjusting clamping plate 8 can still be connected to the fixed clamping plate 10 through the connecting structure when it moves away from the fixed clamping plate 10.

[0024] In addition, through the cooperation of the moving block 15 and the lead screw 13, the technical effect of driving the moving block 15 to move by the lead screw 13 and simultaneously driving the adjusting clamping plate 8 and the fixed clamping plate 10 to move is achieved, and the technical problem that the adjusting clamping plate 8 and the fixed clamping plate 10 can only be installed with a single-height rotor 14 is solved.

[0025] Furthermore, the diameter adjustment module includes a connecting sleeve plate 4, a connecting inner plate 5 and an electric push rod 17. The connecting inner plate 5 is slidably arranged inside the connecting sleeve plate 4. The bottom end of the electric push rod 17 is fixedly arranged on one side of the support base plate 2, the working end of the electric push rod 17 is connected to the connecting sleeve plate 4, the connecting sleeve plate 4 is fixedly connected to a group of adjusting clamping plates 8, and the connecting inner plate 5 is fixedly connected to the other group of adjusting clamping plates 8; a limit block 23 is fixedly arranged on the lower surface of the connecting inner plate 5, a telescopic groove 24 corresponding to the connecting inner plate 5 is opened inside the connecting sleeve plate 4, a second limit groove 25 corresponding to the limit block 23 is opened on the upper surface of the connecting sleeve plate 4, and the telescopic groove 24 and the second limit groove 25 are communicated. Specifically, the electric push rod 17 is set as a push rod with a built-in battery, and the model can be Firgelli L12-WiFi. The electric push rod 17 drives the connecting sleeve plate 4 and the lower adjusting clamping plate 8 to move. The connecting sleeve plate 4 then drives the connecting inner plate 5 to move, and the connecting inner plate 5 then drives the upper adjusting clamping plate 8 to move. Through the cooperation of the connecting sleeve plate 4, the connecting inner plate 5 and the electric push rod 17, the technical effect of driving the two groups of adjusting clamping plates 8 to move away from or close to the corresponding fixed clamping plates 10 is achieved, and the technical problem that the adjusting clamping plate 8 and the fixed clamping plate 10 can only install a rotor 14 with a single diameter is solved.

[0026] Furthermore, a balance adjustment component for adjusting the center of gravity of the rotor 14 is provided on the outer arc surface of the rotor 14; the balance adjustment component includes a fixed ring 7, a rotating column 19 and a configuration block 20. The fixed ring 7 is fixedly sleeved on the outer arc surface of the rotor 14, and the fixed ring 7 is arranged inside the stator 6. A plurality of groups of the rotating column 19 and the configuration block 20 are provided. A plurality of groups of the configuration blocks 20 are slidably arranged inside the fixed ring 7, and the configuration block 20 is threadedly sleeved on the outer arc surface of the corresponding rotating column 19. The configuration block 20 is set as a convex block, and a plurality of groups of adjustment grooves 22 corresponding to the configuration block 20 are opened on the outer arc surface of the fixed ring 7. A plurality of groups of the rotating columns 19 are rotatably arranged inside the corresponding adjustment grooves 22, and a keyway and a flat key are processed on the non-threaded section of the rotating column 19 to form circumferential fixation with the bearing seat inside the fixed ring 7, so as to prevent the rotating column 19 from rotating. By rotating the rotating column 19, the configuration block 20 is driven to move up and down inside the fixed ring 7, so as to adjust the center of gravity of the rotor 14 according to different positions of the configuration block 20; For example, when the motor rotor 14 vibrates greatly in a certain direction, the position of the configuration block 20 at the corresponding position in this direction can be adjusted to increase the mass at this position, so as to change the center of gravity position of the motor rotor 14, and realize the balance adjustment of the motor rotor 14. Through the cooperation of the rotating column 19 and the configuration block 20, the technical effect of adjusting the balance of the rotor 14 is achieved, and the technical problem that the unstable operation is caused by the imbalance of the rotor 14 is solved.

[0027] Specifically, the fixed ring 7 is designed and installed on the outer arc surface of the rotor 14, so as to avoid negative impacts on the drive between the stator 6 and the rotor 14. The drive between the stator 6 and the rotor 14 mainly depends on the principle of electromagnetic induction, and the stability and interaction of the air gap magnetic field between the two are the keys to realizing the drive.

[0028] The fixed ring 7 is precisely installed to ensure its concentricity with the rotor 14 without changing the electromagnetic characteristics of the outer contour of the rotor 14, so as to maintain the stable distribution of the air-gap magnetic field, enable the normal electromagnetic drive between the rotor and the stator, and a number of ventilation grooves are provided on the outer arc surface of the fixed ring 7, and the ventilation grooves are not communicated with the adjustment grooves 22; when the motor operates, the electromagnetic interaction between the stator 6 and the rotor 14 will generate heat, especially when rotating at high speed, the temperature rises significantly. The fixed ring 7 wraps around the rotor 14, which to a certain extent hinders the heat dissipation. The ventilation grooves can make the air flow better inside the motor, take out the heat generated by the rotor, avoid affecting the motor performance due to high temperature, and extend the service life of the motor; at the same time, after the configuration block 20 moves, the air flows through the ventilation grooves, which has an impact on the aerodynamic environment around the rotor 14; In some cases, it can help further fine-tune the balance state of the rotor and improve the accuracy of balance adjustment; in addition, when the motor rotor 14 rotates at high speed, it will generate air resistance by rubbing against the surrounding air, consuming energy and affecting the motor efficiency. The ventilation grooves can break the boundary layer of the air on the surface of the rotor 14, reduce the air resistance, and improve the energy utilization efficiency of the motor. Especially in application scenarios with strict energy consumption requirements, this effect can show obvious advantages.

[0029] In addition, the top end of the lead screw 13 penetrates through the limit frame 11, the top ends of a number of the rotating columns 19 penetrate through the fixed ring 7, and operation holes are provided at the top ends of the limit frame 11 and the rotating columns 19, which facilitates the staff to drive the lead screw 13 and the rotating columns 19 to rotate through the operation holes. Two limit rings 21 are symmetrically arranged on the outer arc surface of a number of the rotating columns 19, and a number of the rotating columns 19 are rotatably arranged inside the fixed ring 7 through the corresponding limit rings 21, and first limit grooves 18 corresponding to the limit rings 21 are provided inside the fixed ring 7, and the limit rings 21 rotate inside the first limit grooves 18, so as to ensure the stability of the rotating columns 19 during rotation, and at the same time, the limit rings 21 are made of materials with a relatively low anti-slip coefficient; Through the cooperation of the first limit grooves 18, the rotating columns 19 and the limit rings 21, the technical effect of ensuring that manual rotation is possible while further preventing the self-rotation of the rotating columns 19 is achieved, the technical problem of the self-rotation of the rotating columns 19 is solved, and the rest of the structures outside the motor stator 6 and the rotor 14 are all made of non-magnetic structures.

[0030] Please refer to Figures 1 - 7 , a robot, including the rotor-balanced frameless motor described in the above-mentioned Embodiment 1. The rotor-balanced frameless motor of the present invention is installed at the joint 27 of the robot 26. When the robot 26 performs an action, the motor rotor 14 rotates at high speed under the drive of the motor. Since the motor rotor 14 has been balanced by the balance adjustment component, it can rotate stably, reducing the generation of vibration and noise.

[0031] For example, when the robot 26 performs the stretching and contracting actions of its arm, the frameless motor at the joint 27 can precisely control the rotation speed and angle of the motor rotor 14, making the arm movements smoother and more accurate. At the same time, due to the design of the connector 1, the support base plate 2, and the size adjustment component, the frameless motor can adapt to the installation of motor rotors 14 with different specifications and sizes. During the research and development and production process of the robot 26, it is possible to according to different design requirements and application scenarios; Drive the adjusting clamping plate 8 away from the rotor 14 through the electric push rod 17, and then remove the support structure 3, the stator 6, and the rotor 14, so as to conveniently replace the motor rotors 14 with different specifications, improve the versatility and adaptability of the robot 26, meet the usage requirements of the robot 26 under different working environments and task requirements, and enhance the overall performance and working efficiency of the robot.

[0032] The above-described embodiments merely represent several embodiments of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation to the scope of the present invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A rotor-balanced frameless motor, comprising a connector, a support base, a support structure, a stator and a rotor, wherein the support structure cooperates with the upper surface of the support base, the stator is fixedly arranged on the inner side of the support structure, the rotor is located at the axis of the support structure, and a connecting column is arranged at one end of the rotor, characterized in that: The outer arc surface of the rotor is provided with a balance adjustment component for adjusting the center of gravity of the rotor; the upper surface of the connector is provided with a size adjustment component for installing rotors of different sizes; The size adjustment assembly includes an adjusting clamp, a fixed clamp, a height adjustment module for adjusting the height of the adjusting clamp and the fixed clamp, and a diameter adjustment module for adjusting the distance between the adjusting clamp and the fixed clamp; The adjusting clamps and the fixing clamps are provided in two groups, the two groups of the adjusting clamps and the fixing clamps are located on both sides of the rotor, and the adjusting clamps and the fixing clamps are provided with mounting grooves on one side close to the rotor.

2. A rotor-balanced frameless motor according to claim 1, characterized in that: The height adjustment module includes a limit frame, a connecting plate, a screw rod, a moving block and a connecting structure. The limit frame is fixedly arranged on the upper surface of the connector, and the connecting plate is slidably arranged on one side of the limit frame through the moving block. The fixed clamping plate is bolted to the side of the connecting plate away from the limit frame, and the moving block is threadedly sleeved on the outer arc surface of the screw rod. The fixed clamping plate is connected to the corresponding adjustment clamping plate through the connecting structure.

3. A rotor-balanced frameless motor according to claim 2, characterized in that: The moving block is configured as a convex block, a moving groove corresponding to the moving block is provided on one side of the limiting frame close to the rotor, and the screw rod is rotatably disposed inside the moving groove.

4. A rotor-balanced frameless motor according to claim 3, characterized in that: The diameter adjustment module includes a connecting sleeve, a connecting inner plate and an electric push rod. The connecting inner plate is slidably arranged inside the connecting sleeve. The bottom end of the electric push rod is fixedly arranged on one side of the supporting bottom plate. The working end of the electric push rod is connected to the connecting sleeve. The connecting sleeve is fixedly connected to a group of adjustment clamps, and the connecting inner plate is fixedly connected to another group of adjustment clamps.

5. A rotor-balanced frameless motor according to claim 4, characterized in that: The balance adjustment component includes a fixed ring, a rotating column and a configuration block. The fixed ring is fixedly sleeved on the outer arc surface of the rotor, and the fixed ring is arranged inside the stator. The rotating column and the configuration block are both provided in several groups. Several groups of configuration blocks are slidably arranged inside the fixed ring, and the configuration blocks are threadedly sleeved on the corresponding outer arc surfaces of the rotating column.

6. A rotor-balanced frameless motor according to claim 5, characterized in that: The configuration block is configured as a convex block, and the outer arc surface of the fixing ring is provided with a plurality of adjustment grooves corresponding to the configuration block, and a plurality of rotation columns are rotatably disposed inside the corresponding adjustment grooves.

7. A rotor-balanced frameless motor according to claim 6, characterized in that: Two groups of limiting rings are symmetrically arranged on the outer arc surfaces of several groups of rotating columns, and several groups of rotating columns are rotatably arranged inside the fixed ring through the corresponding limiting rings, and the fixed ring is provided with a first limiting groove corresponding to the limiting ring.

8. The rotor-balanced frameless motor according to claim 5, characterized in that: The top end of the screw rod passes through the limit frame, and the top ends of the plurality of rotating columns pass through the fixing ring, and the limit frame and the top ends of the rotating columns are both provided with operating holes.

9. The rotor-balanced frameless motor according to claim 4, characterized in that: A limiting block is fixedly arranged on the lower surface of the connecting inner plate, a telescopic groove corresponding to the connecting inner plate is opened inside the connecting sleeve plate, a second limiting groove corresponding to the limiting block is opened on the upper surface of the connecting sleeve plate, and the telescopic groove and the second limiting groove are connected.

10. A robot, characterized in that: A rotor-balanced frameless motor comprising the above claims 1 to 9.

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