Mecanum wheel with damping function

Abstract

The Mecanum wheel with the damping function comprises a rim used for installing a double-layer roller set, the rim is installed on a hub, and the rim comprises an inner-layer roller installation frame, a middle-layer roller installation frame and an outer-layer roller installation frame which are arranged in parallel; a plurality of rollers are uniformly distributed and mounted between the inner-layer roller mounting frame and the middle-layer roller mounting frame in the circumferential direction to form an inner-layer roller group, a plurality of rollers are uniformly distributed and mounted between the middle-layer roller mounting frame and the outer-layer roller mounting frame in the circumferential direction to form an outer-layer roller group, and an elastic body layer is arranged on the periphery of each roller. According to the Mecanum wheel, vibration caused by the structure problem of the Mecanum wheel can be eliminated.

Description

Technical Field

[0001] The invention relates to the technical field of Mecanum wheel vibration reduction, and in particular to a Mecanum wheel with a vibration reduction function. Background Art

[0002] The Mecanum wheel is an omnidirectional wheel structure. It is composed of a driving wheel hub and a driven wheel roller based on the principle of a central roller. The rollers are evenly distributed around the hub at a certain angle. The hub is driven by a motor system, and the rollers do not have a driving function. By reasonably designing the roller surface, the profile of the Mecanum wheel can be made to approximate a complete circle to ensure continuous contact between the roller and the ground. However, during the period when the roller is alternately grounded, the contact point is actually not continuous. This discontinuous contact will cause vertical vibration of the Mecanum wheel system. Each Mecanum wheel is in a different position state, causing random vibration of the motion platform. When the motion platform is used for heavy weight transportation, the impact of this vibration will be amplified, seriously affecting the use of the equipment. At present, there are few studies on this issue, and most studies tend to avoid this situation by designing shock absorbers. However, shock absorbers have strict requirements for the load-bearing weight, which greatly limits the application scenarios of Mecanum wheels. When the Mecanum wheel is used for heavy weight transportation, the vibration will not only affect the positioning accuracy of the vehicle, but also pose a safety hazard to other structures of the vehicle. Summary of the invention

[0003] The object of the present invention is to provide a Mecanum wheel with a vibration elimination function to eliminate the vibration caused by the structural problems of the Mecanum wheel itself.

[0004] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a Mecanum wheel with a vibration-absorbing function, comprising a rim for mounting a double-layer roller group, the rim being mounted on a wheel hub, the rim comprising an inner roller mounting frame, a middle roller mounting frame and an outer roller mounting frame arranged in parallel, a plurality of rollers being evenly installed along the circumferential direction between the inner roller mounting frame and the middle roller mounting frame to form an inner roller group, a plurality of rollers being evenly installed along the circumferential direction between the middle roller mounting frame and the outer roller mounting frame to form an outer roller group, and an elastomer layer being provided on the outer periphery of each roller.

[0005] Furthermore, n roller shaft mounting holes are evenly arranged on the circumference of the inner roller mounting frame; n roller shaft mounting holes are evenly arranged on the circumference of the outer roller mounting frame; 2n roller shaft mounting holes are evenly arranged on the circumference of the middle roller mounting frame, wherein n roller shaft mounting holes face inward and correspond to the roller shaft mounting holes on the inner roller mounting frame, and are used to install the inner rollers, and the other n roller shaft mounting holes face outward and correspond to the roller shaft mounting holes on the outer roller mounting frame, and are used to install the outer rollers; both ends of the roller shaft of each roller are respectively fixedly connected to the corresponding roller shaft mounting holes of two adjacent roller mounting frames.

[0006] Furthermore, the axes of each installed roller form an angle of 45° with the axis of the hub; the central angle between the axes of two adjacent inner rollers is 360 / n degrees, the central angle between the axes of two adjacent outer rollers is 360 / n degrees, and the central angle between the axes of adjacent inner rollers and outer rollers is 180 / n degrees.

[0007] Furthermore, 8 roller shaft mounting holes are evenly arranged on the circumference of the inner roller mounting frame, 8 roller shaft mounting holes are evenly arranged on the circumference of the outer roller mounting frame, and 16 roller shaft mounting holes are evenly arranged on the circumference of the middle roller mounting frame; the central angle between the roller shaft axes of two adjacent inner rollers is 45°, the central angle between the roller shaft axes of two adjacent outer rollers is 45°, and the central angle between the roller shaft axes of adjacent inner rollers and the roller shaft axes of the outer roller is 22.5°.

[0008] Furthermore, the roller includes a roller shaft, a bearing, a roller steel core and an elastomer layer, the roller steel core is sleeved on the outside of the roller shaft, and its two ends are rotatably connected to the roller shaft through bearings, and the elastomer layer is coated on the outer periphery of the roller steel core.

[0009] Furthermore, the roller also includes a sleeve, a bearing retaining ring and an elastic retaining ring, and the bearing includes a thrust bearing and a needle bearing; the roller shaft is a stepped shaft with a stepped convex portion in the middle section, and the sleeve is installed on the outside of the stepped convex portion, and needle bearings are installed on the left and right ends of the stepped convex portion and the sleeve respectively to bear radial loads and perform radial positioning, and thrust bearings are installed next to the needle bearings to bear axial loads, and the left and right ends of the roller steel core are both installed on the needle bearings and the thrust bearings, and there is a gap between the roller steel core and the sleeve to reduce wear; a bearing retaining ring is installed next to the thrust bearing to limit the axial position of the bearing on the roller shaft, and an elastic retaining ring is installed next to the bearing retaining ring to fix various components.

[0010] Furthermore, the thickness of the elastic layer of the roller is different on the cross section at different positions of the roller, so that the contact area between the Mecanum wheel and the ground is the same during the rolling process and the rolling radius of the Mecanum wheel is a constant value.

[0011] Furthermore, the outer surface of the roller has a roller generatrix that meets the tangency requirement, and the curvature radius of the outer surface of the roller at the contact point with the ground is the same.

[0012] Furthermore, in order to ensure that the curvature radius of the contact point between the outer surface of the roller and the ground is the same, the method of vector projection of the roller axis to the cylindrical surface of the design circle is adopted, so that the outer surface of the roller is tangent to the cylindrical surface where the design circle is located; the generatrix equation of the roller is constructed as follows:

[0013]

[0014] The rectangular coordinate system is established with the cross section of the hub where the convergence point A at one end of the roller generatrix is ​​located as the xoy plane, the intersection of the xoy plane and the hub axis is the center point O, the OA line is the x-axis, and the direction of the hub axis toward the other convergence point B of the roller generatrix is ​​the z-axis; x, y, z represent the x, y, and z coordinates of any point F on the roller generatrix, respectively, and θ represents the angle between any point F on the roller generatrix and the x-axis. The value range of θ is D is the minimum distance between the roller axis and the hub axis; R is the hub radius.

[0015] Furthermore, the elastomer layer is made of superelastic material.

[0016] Compared with the prior art, the present invention has the following beneficial effects: the present invention provides a Mecanum wheel with a vibration elimination function, which ensures that the grounding area at the grounding point of the grounding roller during the rolling process is the same and large enough through the innovative double-layer roller group structure design, and at the same time, the rolling radius is ensured to be the same through the compression of the elastic layer to eliminate the vibration caused by the change of the grounding area and the rolling radius during the rolling process of the Mecanum wheel, thereby solving the vibration problem caused by the structural defects of the Mecanum wheel itself. Therefore, the present invention has strong practicality and broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the three-dimensional structure of a Mecanum wheel according to an embodiment of the present invention;

[0018] Figure 2 for Figure 1 The front view of the Mecanum wheel is shown;

[0019] Figure 3 for Figure 1 Side view of the Mecanum wheel shown;

[0020] Figure 4 Schematic diagram of the connection structure between the roller shaft and the rim in an embodiment of the present invention;

[0021] Figure 5Schematic diagram of the internal structure of the roller in an embodiment of the present invention;

[0022] Figure 6 This is a schematic diagram of the structure of a Mecanum wheel set in an embodiment of the present invention;

[0023] Figure 7 This is a schematic diagram of the structure of a mobile platform in an embodiment of the present invention;

[0024] In the figure: 1- roller; 2- roller shaft; 3- inner roller mounting frame; 4- middle roller mounting frame; 5- outer roller mounting frame; 6- wheel hub; 21- shaft bolt; 22- shaft gasket; 11- elastomer layer; 12- roller steel core; 13- elastic retaining ring; 14- bearing retaining ring; 15- thrust bearing; 16- needle bearing; 17- bushing; 100- Mecanum wheel; 101- motor; 102- coupling; 103- reducer; 104- suspension; 200- Mecanum wheel set; 300- platform; 400- battery box. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0026] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0027] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0028] The present invention provides a Mecanum wheel with a vibration-absorbing function, which has a double-layer roller set design and a variable-thickness elastomer layer coated on the roller. The double-layer roller set design arranges two rows of rollers along the axial direction of the Mecanum wheel and makes the two rows of rollers differ by a certain angle, so as to ensure that when a single-layer roller is in a junction position, the other layer of rollers is just in the middle section, thereby solving the vibration of the Mecanum wheel caused by the transition of the rollers during the rolling process of the Mecanum wheel. The envelope surface formed by the outer surface of the roller with the variable-thickness elastomer layer is a cylindrical surface with the hub axis as the center line. At the same time, the elastomer layer is thicker at the position with a smaller circumferential section radius on both sides of the roller, and the elastomer layer is thinner at the position with a larger circumferential section radius in the middle of the roller, so that the corresponding contact area and rolling radius at different positions during the rolling process are equal. Therefore, the present invention can eliminate the vibration caused by the structural problem of the Mecanum wheel itself.

[0029] like Figure 1-5 As shown, the Mecanum wheel with vibration absorption function provided in this embodiment includes a rim for mounting a double-layer roller group, the rim is mounted on a hub 6 by bolts, the rim includes an inner roller mounting frame 3, a middle roller mounting frame 4 and an outer roller mounting frame 5 arranged in parallel, a plurality of rollers 1 are evenly installed along the circumferential direction between the inner roller mounting frame 3 and the middle roller mounting frame 4 to form an inner roller group, a plurality of rollers 1 are evenly installed along the circumferential direction between the middle roller mounting frame 4 and the outer roller mounting frame 5 to form an outer roller group, and each roller 1 has an elastomer layer 11 with variable thickness on its outer periphery.

[0030] The inner roller mounting frame 3 is evenly provided with n roller shaft mounting holes on its circumference; the outer roller mounting frame 5 is evenly provided with n roller shaft mounting holes on its circumference; the middle roller mounting frame 4 is evenly provided with 2n roller shaft mounting holes on its circumference, wherein n roller shaft mounting holes face inwards and correspond to the roller shaft mounting holes on the inner roller mounting frame, and are used to install the inner rollers; the other n roller shaft mounting holes face outwards and correspond to the roller shaft mounting holes on the outer roller mounting frame, and are used to install the outer rollers; the two ends of the roller shaft 2 of each roller are fixedly connected to the corresponding roller shaft mounting holes of the two adjacent roller mounting frames by threaded fasteners. Figure 4 As shown, the roller shaft 2 has threads at both ends, passing through the outer roller mounting hole and the middle roller mounting hole, the inner roller mounting hole and the middle roller mounting hole respectively. The roller shaft 2 is connected to the roller mounting frame by bolts 21, and a gasket 22 is used between the bolts 21 and the roller mounting frame to prevent loosening.

[0031] The axis of each installed roller forms an angle of 45° with the axis of the hub; the central angle between the axes of two adjacent inner rollers is 360 / n degrees, the central angle between the axes of two adjacent outer rollers is 360 / n degrees, and the central angle between the axes of adjacent inner rollers and outer rollers is 180 / n degrees.

[0032] In this embodiment, the inner roller mounting frame is evenly provided with 8 roller shaft mounting holes, the outer roller mounting frame is evenly provided with 8 roller shaft mounting holes, and the middle roller mounting frame is evenly provided with 16 roller shaft mounting holes; the center angle between the roller shaft axes of two adjacent inner rollers is 45°, the center angle between the roller shaft axes of two adjacent outer rollers is 45°, and the center angle between the roller shaft axes of adjacent inner rollers and the roller shaft axes of the outer roller is 22.5°. Through this angle design, it can be ensured that when a single layer of rollers is in the intersection position, the other layer of rollers is just in the middle section, thereby solving the vibration of the Mecanum wheel caused by the roller transition during the rolling process of the Mecanum wheel.

[0033] It should be noted that the number of rollers in a single-layer roller group is not limited to 8 and should be reasonably selected according to actual conditions. However, the angle between the inner and outer rollers should be ensured so that when the single-layer roller is at the intersection, the other layer of rollers is just in the middle, thereby solving the vibration of the Mecanum wheel caused by the transition of the rollers during the rolling process of the Mecanum wheel.

[0034] In this embodiment, the roller 1 includes a roller shaft 2, a bearing, a roller steel core 12, an elastic layer 11, a sleeve 17, a bearing retaining ring 14 and an elastic retaining ring 13, and the bearing specifically includes a thrust bearing 15 and a needle bearing 16. The roller steel core 12 is sleeved on the outside of the roller shaft 2, and its two ends are rotatably connected to the roller shaft through bearings, and the elastic layer is coated on the outer periphery of the roller steel core, and the inner surface of the elastic layer is in close contact with the outer surface of the roller steel core. The roller shaft 2 is a stepped shaft with a stepped convex portion in the middle section, the sleeve 17 is installed on the outside of the stepped convex portion, needle bearings 16 are installed on the left and right ends of the stepped convex portion and the sleeve respectively to bear radial loads and perform radial positioning, thrust bearings 15 are installed next to the needle bearings 16 to bear axial loads, the left and right ends of the roller steel core 12 are installed on the needle bearings 16 and the thrust bearings 15, and there is a gap between the roller steel core 12 and the sleeve 17 to reduce wear; a bearing retaining ring 14 is installed next to the thrust bearing 15 to limit the axial position of the bearing on the roller shaft, and an elastic retaining ring 13 is installed next to the bearing retaining ring 14 to fix various components.

[0035] The thickness of the elastomer layer 11 of the roller 1 is different on the cross-section at different positions of the roller. The thickness of the elastomer layer is determined by the roller radius and the number of rollers at the ground contact position. The elastomer layer is thicker at positions with smaller cross-section radius on both sides of the roller, and is thinner at positions with larger cross-section radius in the middle of the roller. This ensures that the contact area between the Mecanum wheel and the ground is the same during rolling and that the rolling radius of the Mecanum wheel is a constant value, thereby solving the Mecanum wheel vibration caused by different ground contact areas and compression amounts of the roller elastomer layer at different circumferential section positions.

[0036] The outer surface of the roller 1 has a roller generatrix that meets the tangency requirement, and the curvature radius of the outer surface of the roller and the ground contact point are the same.

[0037] The envelope formed by the outer surface of the roller is a cylindrical surface with the hub axis as the center line. In order to ensure that the radius of curvature of the outer surface of the roller and the ground contact point is the same, the method of vector projection of the roller axis to the cylindrical surface of the design circle is adopted to make the outer surface of the roller tangent to the cylindrical surface where the design circle is located. In order to simplify the design process, based on the formation principle of the roller, the generatrix equation of the roller is constructed as follows:

[0038]

[0039] The rectangular coordinate system is established with the cross section of the hub where the convergence point A at one end of the roller generatrix is ​​located as the xoy plane, the intersection of the xoy plane and the hub axis is the center point O, the OA line is the x-axis, and the direction of the hub axis toward the other convergence point B of the roller generatrix is ​​the z-axis; x, y, z represent the x, y, and z coordinates of any point F on the roller generatrix, respectively, and θ represents the angle between any point F on the roller generatrix and the x-axis. The value range of θ is D is the minimum distance between the roller axis and the hub axis; R is the hub radius.

[0040] The length of the roller can be determined according to actual needs, and the roller has the characteristics of different circumferential section radii, which leads to changes in the contact area. A shorter roller radius provides a larger contact area, so the contact area of ​​the roller should be reasonably designed to ensure the stability of the contact area during rolling.

[0041] The elastomer layer 11 is made of a superelastic material. The superelastic material has the characteristics of undergoing a very large deformation under the action of an external force, returning to the initial state after the external force is removed, and being incompressible. Different materials should be selected according to the need for more cushioning and shock absorption effects, the need for additional hardness and support during large deformations, or the need to maintain a high hardness and rigidity within a small deformation range while maintaining a relatively gentle hardening effect during large deformations.

[0042] Figure 6 A complete Mecanum wheel assembly based on the Mecanum wheel provided in this embodiment is shown. The Mecanum wheel assembly is composed of a motor 101, a coupling 102, a reducer 103, a Mecanum wheel 100, and a suspension 104. The motor 101 provides power, which is transmitted to the reducer 103 through the coupling 102. After the reducer reduces the power, the power is transmitted to the Mecanum wheel 100 having a variable thickness elastic coating layer and a double-layer roller. There is a connecting plate between the suspension and the reducer, which are connected by bolts; bolts are arranged on the upper surface of the suspension, which can be connected to the platform 300.

[0043] Figure 7 A mobile platform 300 implemented by the Mecanum wheel set 200 provided in this embodiment is shown. The mobile platform 300 is rectangular, and has bolt holes on its lower surface corresponding to the upper surface of the suspension, and the Mecanum wheel set 200 is connected by bolts.

[0044] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A Mecanum wheel with vibration elimination function, characterized in that: It comprises a rim for mounting a double-layer roller group, the rim being mounted on a wheel hub, the rim comprising an inner roller mounting frame, a middle roller mounting frame and an outer roller mounting frame which are arranged in parallel, a plurality of rollers being evenly mounted along the circumferential direction between the inner roller mounting frame and the middle roller mounting frame to form an inner roller group, a plurality of rollers being evenly mounted along the circumferential direction between the middle roller mounting frame and the outer roller mounting frame to form an outer roller group, and an elastomer layer being provided on the outer periphery of each roller.

2. A Mecanum wheel with vibration-absorbing function according to claim 1, characterized in that: The inner roller mounting frame is evenly provided with n roller shaft mounting holes on its circumference; the outer roller mounting frame is evenly provided with n roller shaft mounting holes on its circumference; the middle roller mounting frame is evenly provided with 2n roller shaft mounting holes on its circumference, wherein n roller shaft mounting holes face inwards and correspond to the roller shaft mounting holes on the inner roller mounting frame for mounting inner rollers, and the other n roller shaft mounting holes face outwards and correspond to the roller shaft mounting holes on the outer roller mounting frame for mounting outer rollers; the two ends of the roller shaft of each roller are respectively fixedly connected to the corresponding roller shaft mounting holes of two adjacent roller mounting frames.

3. The Mecanum wheel with vibration-absorbing function according to claim 2, characterized in that: The axis of each installed roller forms an angle of 45° with the axis of the hub; the central angle between the axes of two adjacent inner rollers is 360 / n degrees, the central angle between the axes of two adjacent outer rollers is 360 / n degrees, and the central angle between the axes of adjacent inner rollers and outer rollers is 180 / n degrees.

4. The Mecanum wheel with vibration-absorbing function according to claim 3, characterized in that: The inner roller mounting frame is evenly provided with 8 roller shaft mounting holes on its circumference, the outer roller mounting frame is evenly provided with 8 roller shaft mounting holes on its circumference, and the middle roller mounting frame is evenly provided with 16 roller shaft mounting holes on its circumference; the central angle between the roller shaft axes of two adjacent inner rollers is 45°, the central angle between the roller shaft axes of two adjacent outer rollers is 45°, and the central angle between the roller shaft axes of adjacent inner rollers and the roller shaft axes of the outer roller is 22.5°.

5. The Mecanum wheel with vibration-absorbing function according to claim 1, characterized in that: The roller comprises a roller shaft, a bearing, a roller steel core and an elastic layer. The roller steel core is sleeved on the outside of the roller shaft and its two ends are rotatably connected to the roller shaft through bearings. The elastic layer is coated on the outer periphery of the roller steel core.

6. The Mecanum wheel with vibration-absorbing function according to claim 5, characterized in that: The roller also includes a sleeve, a bearing retaining ring and an elastic retaining ring, and the bearing includes a thrust bearing and a needle bearing; the roller shaft is a stepped shaft with a stepped convex portion in the middle section, and the sleeve is installed on the outside of the stepped convex portion, and needle bearings are installed on the left and right ends of the stepped convex portion and the sleeve respectively to bear radial loads and perform radial positioning, and thrust bearings are installed next to the needle bearings to bear axial loads, and the left and right ends of the roller steel core are both installed on the needle bearings and the thrust bearings, and there is a gap between the roller steel core and the sleeve to reduce wear; a bearing retaining ring is installed next to the thrust bearing to limit the axial position of the bearing on the roller shaft, and an elastic retaining ring is installed next to the bearing retaining ring to fix various components.

7. The Mecanum wheel with vibration-absorbing function according to claim 1, characterized in that: The thickness of the elastic layer of the roller on the cross section at different positions of the roller is different, so that the contact area between the Mecanum wheel and the ground is the same during the rolling process and the rolling radius of the Mecanum wheel is a constant value.

8. The Mecanum wheel with vibration-absorbing function according to claim 1, characterized in that: The outer surface of the roller has a roller generatrix that meets the tangency requirement, and the curvature radius of the outer surface of the roller and the ground contact point are the same.

9. The Mecanum wheel with vibration-absorbing function according to claim 8, characterized in that: In order to ensure that the curvature radius of the roller outer surface and the ground contact point is the same, the roller axis is projected onto the cylindrical surface of the design circle by vector, so that the roller outer surface is tangent to the cylindrical surface where the design circle is located. The generatrix equation of the roller is constructed as follows: The rectangular coordinate system is established with the cross section of the hub where the convergence point A at one end of the roller generatrix is ​​located as the xoy plane, the intersection of the xoy plane and the hub axis is the center point O, the OA line is the x-axis, and the direction of the hub axis toward the other convergence point B of the roller generatrix is ​​the z-axis; x, y, z represent the x, y, and z coordinates of any point F on the roller generatrix, respectively, and θ represents the angle between any point F on the roller generatrix and the x-axis. The value range of θ is D is the minimum distance between the roller axis and the hub axis; R is the hub radius.

10. The Mecanum wheel with vibration-absorbing function according to claim 1, characterized in that: The elastomer layer is made of superelastic material.

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