Linkage variable-diameter wheel structure based on rhombus instability characteristic and cylindrical cam

Abstract

The invention discloses a linkage variable-diameter wheel structure based on the rhombus instability characteristic and a cylindrical cam, and relates to the technical field of variable-diameter wheel design. The sliding way support is provided with a plurality of sliding ways, guide rollers are arranged at the bottoms of reducing rods matched in the sliding ways, the cam support is composed of a center block and an annular frame, a plurality of cylindrical cams with spiral guide grooves are rotationally installed between the center block and the annular frame, driven bevel gears are fixed to the bottoms of the cylindrical cams, and the driving bevel gear is meshed with the driven bevel gears. A wheel center shaft is coaxially fixed to the slide way support and sleeved with the cam support and the driving bevel gear, the guide rollers extend into the corresponding spiral guide grooves, the two ends of the diagonal line of each rhombic four-connecting-rod unit are hinged to the edges of the top ends of the two adjacent variable-diameter rods, the main tire body is fixed to the middle of the top ends of the variable-diameter rods, and the auxiliary tire bodies are fixed to the two ends of the other diagonal line of each rhombic four-connecting-rod unit. The tire bodies are additionally arranged at the diagonal lines of the rhombus, perimeter change before and after diameter change of the wheel body is achieved through instability of the rhombus, meanwhile, wheel width change is achieved, and stability is improved.

Description

Technical Field

[0001] The invention relates to the technical field of variable diameter wheel design, in particular to a linkage variable diameter wheel structure based on rhombus unstable characteristics and a cylindrical cam. Background Art

[0002] Wheel adaptability and maneuverability are key factors influencing vehicle performance. For example, at high speeds, larger wheels provide greater stability and improved obstacle handling. At low speeds or on rough roads, smaller wheels improve flexibility and maneuverability. However, traditional wheel designs often utilize a fixed radial size, making them unable to adapt to driving conditions or the external environment.

[0003] In view of this, industry insiders have proposed the design concept of a variable diameter wheel, which achieves size changes by changing the diameter of the wheel body to adapt to the use requirements of different site environments. However, the variable diameter wheel structures currently proposed basically simply change the diameter of the wheel body through various telescopic mechanisms, lacking a joint consideration of the wheel body diameter change and wheel width change. Moreover, the wheel circumference before and after the wheel body changes in diameter lacks effective support due to the widening of the gap caused by the elongation of the components, resulting in a large difference in the stability of the wheel body before and after the diameter change. Therefore, there is an urgent need for a variable diameter wheel structure that can adjust the radial size and wheel width changes according to different working conditions, and at the same time ensure that there is always effective support at the wheel circumference gap position before and after the wheel body changes in diameter. This is of great significance for improving the stability of the variable diameter wheel structure. Summary of the Invention

[0004] In order to address the shortcomings of the background technology, the present invention provides a linked variable diameter wheel structure based on the unstable characteristics of the diamond and a cylindrical cam. It uses the instability of the diamond to realize the change of the circumference of the wheel body before and after the diameter change, and adds a carcass at the diagonal of the diamond to realize the change of wheel width while changing the diameter. Moreover, the wheel circumference is always effectively supported by the diamond four-bar unit, thereby improving the stability before and after the diameter change.

[0005] To achieve the above-mentioned object, the present invention adopts the following technical solutions: a linkage variable diameter wheel structure based on the diamond instability characteristic and the cylindrical cam, comprising a carcass, a diameter-changing mechanism, a driving mechanism, a wheel center shaft, and a plurality of diamond-shaped four-bar linkage units;

[0006] The diameter-changing mechanism includes a slideway bracket and a plurality of diameter-changing rods. The slideway bracket is composed of a plurality of slideways arranged along the radial direction of the wheel body. The plurality of slideways are evenly arranged along the circumference of the wheel body and are made into one body. The plurality of diameter-changing rods are matched with the plurality of slideways and have guide rollers arranged vertically at the bottom.

[0007] The driving mechanism includes a cam bracket, a driving bevel gear, a plurality of driven bevel gears and a plurality of cylindrical cams. The cam bracket is composed of a coaxially arranged center block and an annular frame. The plurality of cylindrical cams are evenly arranged and rotatably mounted between the two parts of the cam bracket. The side walls of the cylindrical cams are provided with spiral guide grooves. The bottom of the cylindrical cams is coaxially fixed with the driven bevel gears. The driving bevel gear is meshed with the plurality of driven bevel gears.

[0008] The wheel center axis is coaxially fixed to the slide bracket, the center block of the cam bracket is mounted on the wheel center axis by setting an axis hole and an active bevel gear, and the guide rollers of the multiple diameter reducing rods are respectively extended into the spiral guide grooves of the corresponding cylindrical cams;

[0009] The plurality of diamond-shaped four-bar linkage units are evenly distributed between the top ends of the plurality of variable-diameter rods, and each diamond-shaped four-bar linkage unit is located at both ends of a diagonal line in the circumference of the wheel body and is hinged to the top edges of two adjacent variable-diameter rods respectively;

[0010] The carcass is divided into a secondary carcass and a main carcass. The main carcass is fixed in the middle of the top end of each reducer, and the secondary carcass is fixed at both ends of the other diagonal of each rhombus four-link unit.

[0011] Furthermore, both ends of the spiral guide groove of the cylindrical cam are respectively provided with horizontal positioning sections.

[0012] Furthermore, when the multiple variable-diameter rods of the linked variable-diameter wheel structure are fully extended, the two secondary carcasses on each of the diamond-shaped four-bar linkage units are arranged flush with the main carcass at both side edges in the wheel width direction.

[0013] Furthermore, a roller sleeve is rotatably provided on the outside of the guide roller of the variable diameter rod.

[0014] Furthermore, the outer surfaces of the auxiliary carcass and the main carcass are both provided with anti-slip patterns.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. The present invention utilizes the instability of the rhombus, which causes the length change of the rhombus diagonal line, to achieve the change in the circumference of the wheel before and after the diameter change. A rhombus-shaped four-bar linkage unit is used to connect the top ends of two adjacent diameter-changing rods. By adding a carcass at the rhombus diagonal line, the number of polygonal sides is doubled, making the wheel body closer to a circle before the diameter change, and making the wheel body more stable before and after the diameter change.

[0017] 2. The wheel body of the present invention can change its diameter and width simultaneously due to the diamond-shaped deformation. When fully extended, the wheel width is narrowest, which can reduce the contact area with the ground to reduce friction, help save power, improve energy utilization, and is suitable for use at high speeds. When fully retracted, the wheel width becomes thicker, and the main carcass and auxiliary carcass are staggered in a concave-convex shape, which increases friction with the ground and has stronger grip, making it suitable for use on rugged and uneven ground and slopes.

[0018] 3. The present invention cooperates with the reducing mechanism and the driving mechanism, utilizes the active bevel gear to drive the driven bevel gear to drive the rotation of multiple cylindrical cams, and indirectly drives multiple reducing rods to move radially in the slide of the slide bracket to achieve the diameter changing action of the wheel body. The linkage structure of the diamond four-bar connecting unit and the cylindrical cam ensures the accuracy and stability of the wheel body diameter changing. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the overall extended state of the linkage variable diameter wheel structure of the present invention;

[0020] Figure 2 This is a schematic diagram of the overall contraction state of the linked variable diameter wheel structure of the present invention;

[0021] Figure 3 This is an assembly diagram of the variable diameter rod and the slideway bracket in the linked variable diameter wheel structure of the present invention;

[0022] Figure 4 This is an assembly diagram of the cylindrical cam and the cam bracket in the linkage variable diameter wheel structure of the present invention;

[0023] Figure 5 This is a schematic diagram of the linkage variable diameter wheel structure of the present invention in an extended state with the carcass omitted;

[0024] Figure 6 This is a schematic diagram of the contracted state of the linked variable diameter wheel structure of the present invention with the carcass omitted;

[0025] Figure 7 This is a theoretical calculation reference diagram for the diamond four-bar linkage unit in the linked variable-diameter wheel structure of the present invention.

[0026] In the figure: 1, auxiliary carcass; 2, main carcass; 3, cam bracket; 4, driven bevel gear; 5, cylindrical cam; 6, diamond four-bar linkage; 7, wheel center shaft; 8, driving bevel gear; 9, slide bracket; 10, reducing rod. DETAILED DESCRIPTION

[0027] The technical solutions of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0028] like Figures 1 to 7 As shown, a linkage variable wheel structure based on the rhombus instability characteristics and the cylindrical cam includes a secondary carcass 1, a main carcass 2, a cam bracket 3, a driven bevel gear 4, a cylindrical cam 5, a rhombus four-bar unit 6, a wheel center shaft 7, an active bevel gear 8, a slide bracket 9 and a variable rod 10.

[0029] Combine Figure 3 As shown, the slide bracket 9 and the plurality of reducing rods 10 constitute a reducing mechanism for realizing radial extension and contraction of the wheel body. Among them, the slide bracket 9 includes a plurality of integrally formed slides, each slide is arranged along the radial direction of the wheel body, and the plurality of slides are evenly arranged along the circumference of the wheel body. Taking eight slides as an example, the slide bracket 9 is in a M-shaped configuration as a whole. The plurality of reducing rods 10 slide in cooperation with the plurality of slides one by one, and can be displaced along the slides in the radial direction of the wheel body. A guide roller is vertically arranged at the bottom of each reducing rod 10 to cooperate with the driving mechanism to realize the displacement control of the reducing rod 10. In order to reduce the friction during the movement of the guide roller, a roller sleeve can be rotatably arranged on the outside of the guide roller, which helps to improve the smoothness of the wheel body diameter changing process;

[0030] Combine Figure 4 As shown, the cam bracket 3, the active bevel gear 8, the multiple driven bevel gears 4 and the multiple cylindrical cams 5 constitute a driving mechanism for controlling the extension and contraction of the multiple diameter-changing rods 10 on the slide bracket 9. Among them, the cam bracket 3 is composed of two parts, a coaxially arranged center block and an annular frame, for loading the multiple cylindrical cams 5. The multiple cylindrical cams 5 are evenly arranged and rotatably mounted between the two parts of the cam bracket 3. Each cylindrical cam 5 is also arranged along the radial direction of the wheel body, and each cylindrical cam 5 has a spiral guide groove on its side wall. The spiral guide groove cooperates with the guide roller to drive the diameter-changing rod 10 to move radially during rotation. In order to ensure the stability of the diameter-changing rod 10 when it is extended to the maximum and contracted to the minimum (corresponding to the maximum and minimum modes of the wheel diameter change), horizontal positioning sections can be formed at both ends of the spiral guide groove of the cylindrical cam 5, so that the guide roller can slide into the horizontal positioning section to maintain the maximum and minimum modes of the wheel diameter change. A driven bevel gear 4 is coaxially fixed to the bottom of each cylindrical cam 5, and the active bevel gear 8 is arranged along the axial direction of the wheel body and can be engaged with multiple driven bevel gears 4 at the same time. Therefore, during the rotation of the active bevel gear 8, all the cylindrical cams 5 can be driven to rotate simultaneously through multiple driven bevel gears 4, thereby realizing the synchronous extension and retraction action of all the variable diameter rods 10.

[0031] Combine Figure 1 As shown, the reducing mechanism and the drive mechanism are assembled via the wheel's central shaft 7, which is coaxially fixed to the slideway bracket 9. Since the guide rollers must mate with the spiral guide grooves, the wheel's central shaft 7 and the guide rollers are naturally located on the same side of the slideway bracket 9. The cam bracket 3's center block is fitted onto the wheel's central shaft 7 through a shaft hole, and the active bevel gear 8 is inserted through its own center hole. This positions the drive mechanism and reducing mechanism adjacently. During assembly, the guide rollers of the multiple reducing rods 10 are inserted into the spiral guide grooves of the corresponding cylindrical cam 5. When the wheel rotates, the wheel's central shaft 7 drives the slideway bracket 9 to rotate. Since the guide rollers of the multiple reducing rods 10 on the slideway bracket 9 extend into the spiral guide grooves of the cylindrical cam 5, they can synchronously drive the cam bracket 3 to rotate accordingly. However, given the potential instability of the cylindrical cam 5 due to its rotating structure, the cam bracket 3 is preferably fixed to the wheel's central shaft 7.

[0032] Combine Figures 5 and 6 As shown, multiple diamond-shaped four-bar linkage units 6 are evenly distributed between the top ends of multiple variable-diameter rods 10. When the diamond-shaped four-bar linkage units 6 are assembled, each diamond-shaped four-bar linkage unit 6 is hinged to the top edges of two adjacent variable-diameter rods 10 at both ends of the diagonal line in the circumference of the wheel body. The four vertices of the diamond-shaped four-bar linkage unit 6 are all hinged, and the diamond shape has unstable characteristics. Therefore, during the extension and contraction process of the multiple variable-diameter rods 10, the diagonal length of the diamond-shaped four-bar linkage unit 6 in the circumference of the wheel body will adaptively change along the tangent direction of the wheel body.

[0033] Combine Figures 1 and 2 As shown, the carcass is divided into two types: a secondary carcass 1 and a main carcass 2. The secondary carcasses 1 are paired, with the main carcass 2 being wider in the wheel width direction and the secondary carcass 1 being narrower in the wheel width direction. A main carcass 2 is fixed to the center of the top of each reducer 10, and two secondary carcasses 1 are fixed to the other diagonal ends of each diamond-shaped four-bar linkage unit 6. The outer surfaces of the secondary carcass 1 and the main carcass 2 are both provided with anti-slip grooves. When all reducers 10 are fully extended, the two secondary carcasses 1 on each diamond-shaped four-bar linkage unit 6 should be flush with the main carcass 2 on both sides of the wheel width direction.

[0034] Taking the inventor's actual product as an example, the number of cylindrical cams 5, diamond-shaped four-bar linkage units 6, and reducers 10 is eight. Therefore, in the fully extended state, the eight main carcasses 2 and eight pairs of auxiliary carcasses 1 form a regular hexadecagon. In the fully extended state, the carcass composed of the eight main carcasses 2 and eight pairs of auxiliary carcasses 1 is a perfect circle with a radius of 230.2 mm. In the fully retracted state, due to the changes in the diamond-shaped four-bar linkage units 6 and reducers 10, the auxiliary carcasses 1 are further outward from the wheel body, and the circumference of the eight pairs of auxiliary carcasses 1 is a perfect circle with a radius of 174.7 mm, resulting in a total wheel diameter reduction ratio of 1.32. In the fully extended state, due to the lengthening of the diagonal of the diamond-shaped four-bar linkage units 6 in the wheel body circumference, the wheel thickness becomes narrower, with a wheel thickness of 120.0 mm based on the carcass. In the fully retracted state, the wheel thickness becomes wider, with a wheel thickness of 158.4 mm based on the carcass, resulting in a total wheel thickness change ratio of 1.32.

[0035] Therefore, the variable-diameter wheel structure of the present invention can achieve not only wheel diameter changes before and after deformation, but also wheel thickness changes. In the fully extended state, the eight main carcasses 2 and eight pairs of auxiliary carcasses 1 on the outer ring of the wheel are located on the same circumference, approximately forming a perfect circle, which can reduce resistance. At the same time, the narrower wheel thickness can reduce the contact area with the ground, reducing friction, allowing the wheel body to be more power-efficient in this state, improve energy utilization, and be suitable for use at high speeds. At the same time, the larger wheel body provides better obstacle-crossing performance, allowing it to climb over obstacles in specific scenarios. In the fully retracted state, the main carcasses and auxiliary carcasses on the outer ring of the wheel are staggered, forming a concave-convex shape, which has greater friction with the ground and stronger grip. At the same time, its wider wheel thickness provides better stability, making the wheel body more suitable for wet and slippery surfaces in this state, preventing slipping, and suitable for use on rugged and uneven ground and slopes. In addition, since the diameter change of the entire wheel is controlled by the active bevel gear 8, it can be equipped with a servo to drive it axially, which can ensure that its torque is sufficient to support the radial force of the entire wheel body. At the same time, the servo can be used to ensure the rotation angle of the active bevel gear 8, thereby limiting the rotation position of the cylindrical cam 5, so that the wheel body can be locked at any position within the diameter change range.

[0036] Combine Figure 7 As shown, the changing process of the diamond four-link unit 6 is as follows:

[0037] Assume that the side length of the rhombus is x, the diagonal length in the circumferential direction of the wheel body is L, the adjacent side angle of the connecting end in the fully contracted state is α, and the adjacent side angle of the connecting end in the fully extended state is β, then the change in the diagonal length of the rhombus is ΔL=2x(cosβ / 2-cosα / 2), and the relationship between the active bevel gear 8 and the radius change during the change is calculated. Since the wheel body has a total of eight reducing rods 10, the angle between adjacent reducing rods 10 is γ=360° / 8=45°. Assume that the wheel body radius is R, simplify the model, and ignore the thickness of the reducing rod 10. Then the diagonal length of the rhombus is L=2Rsin(γ / 2), and its change also satisfies ΔL=2ΔRsin(γ / 2). In this embodiment, the transmission ratio of the driving bevel gear 8 to the driven bevel gear 4 is 10:3. Assuming that the angular change of the driving bevel gear 8 is Δθ, and since the ratio of their angular velocities ω1:ω2=3:10, the angular change of the driven bevel gear 4 is (10 / 3)Δθ. Since the cylindrical cam 5 and the driven bevel gear 4 are relatively stationary, their angular changes remain consistent, and the linear velocities of the driving bevel gear 8 and the driven bevel gear 4 remain consistent. Moreover, the reference radius of the driven bevel gear 4 is r=12.7 mm, so the rotation arc length of the driven bevel gear 4 is Δl=10 / 3rΔθ. If the horizontal positioning section of the spiral guide groove of the cylindrical cam 5 is ignored and the slope of the spiral guide groove is k, then the radial change and the wheel radius change ΔR=(10 / 3)rkΔθ.

[0038] From the above formulas, we can obtain: the maximum rotation angle of the active bevel gear 8 Δθmax = 3x(cosβ / 2-cosα / 2) / 10rksin(γ / 2), the maximum change in the wheel radius ΔRmax = x(cosβ / 2-cosα / 2) / sin(γ / 2), since in this embodiment α = 120°, β = 78°, γ = 45°, x = 80.0 mm, r = 12.7 mm, k = 0.44, substituting into the above formulas, we can obtain Δθmax = 178.1°, the measured rotatable angle of the active bevel gear 8 is Δθr = 176.3°, and the error rate η = (Δθmax-Δθr)*100% / Δθmax = 1.0%. Substituting the data, the maximum change in wheel radius ΔRmax = 57.3 mm, while the actual measured maximum change in wheel radius ΔRr = 55.5 mm, the error rate η = (ΔRmax-ΔRr)*100% / ΔRmax = 3.1%, which proves that the principle formula of the variable diameter structure of the present invention is consistent with the actual situation.

[0039] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other configurations without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations coming within the meaning and range of equivalents of the claims are intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0040] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A linkage variable diameter wheel structure based on rhombus instability characteristics and cylindrical cam, characterized by: It comprises a carcass, a diameter-changing mechanism, a driving mechanism, a wheel center shaft (7), and a plurality of diamond-shaped four-link units (6); The diameter-changing mechanism comprises a slideway bracket (9) and a plurality of diameter-changing rods (10), wherein the slideway bracket (9) is composed of a plurality of slideways arranged along the radial direction of the wheel body, the plurality of slideways are evenly arranged along the circumference of the wheel body and are formed into one body, the plurality of diameter-changing rods (10) are matched with the plurality of slideways and a guide roller is arranged at the bottom in the vertical direction; The driving mechanism comprises a cam bracket (3), a driving bevel gear (8), a plurality of driven bevel gears (4) and a plurality of cylindrical cams (5); the cam bracket (3) is composed of a coaxially arranged center block and an annular frame; the plurality of cylindrical cams (5) are evenly arranged and rotatably mounted between the two parts of the cam bracket (3); a spiral guide groove is formed on the side wall of the cylindrical cam (5); the bottom of the cylindrical cam (5) is coaxially fixed with the driven bevel gear (4); the driving bevel gear (8) is meshed with the plurality of driven bevel gears (4); The wheel center shaft (7) is coaxially fixed to the slide bracket (9), the center block of the cam bracket (3) is mounted on the wheel center shaft (7) by providing an axis hole and an active bevel gear (8), and the guide rollers of the plurality of diameter-changing rods (10) are respectively extended into the spiral guide grooves of the corresponding cylindrical cams (5); The plurality of diamond-shaped four-link units (6) are evenly distributed between the top ends of the plurality of variable diameter rods (10), and each diamond-shaped four-link unit (6) is located at both ends of a diagonal line in the circumferential direction of the wheel body and is hinged to the top edges of two adjacent variable diameter rods (10). The carcass is divided into a secondary carcass (1) and a main carcass (2); the main carcass (2) is fixed at the middle of the top end of each reducing rod (10); and the secondary carcass (1) is fixed at the other two diagonal ends of each rhombus four-link unit (6).

2. The linkage variable wheel structure based on the rhombus instability characteristic and the cylindrical cam according to claim 1 is characterized in that: Horizontal positioning sections are respectively formed at both ends of the spiral guide groove of the cylindrical cam (5).

3. The linkage variable diameter wheel structure based on the rhombus instability characteristic and the cylindrical cam according to claim 1 is characterized in that: When the multiple variable diameter rods (10) of the linked variable diameter wheel structure are in a fully extended state, the two secondary carcasses (1) on each of the diamond-shaped four-link units (6) are arranged flush with the main carcass (2) at both side edges in the wheel width direction.

4. The linkage variable wheel structure based on the rhombus instability characteristic and the cylindrical cam according to claim 1 is characterized in that: A roller sleeve is rotatably arranged on the outside of the guide roller of the diameter-changing rod (10).

5. The linkage variable diameter wheel structure based on the rhombus instability characteristic and the cylindrical cam according to claim 1 is characterized in that: The outer surfaces of the auxiliary carcass (1) and the main carcass (2) are both provided with anti-skid patterns.

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