Bearingless integrated light and small rotary joint and design method thereof

Abstract

The invention discloses a bearingless integrated light and small rotating joint and a design method thereof, and belongs to the field of aerospace pneumatic deceleration. The rotary joint comprises an upper connecting ring, a connecting shaft, a retainer, a ball and a lower connecting ring; a raceway is arranged on the upper connecting ring and provides a raceway surface for circumferential rolling of the balls; a roller path is arranged on the connecting shaft, and another roller path surface is provided for circumferential rolling of the balls; the retainer is positioned between the upper connecting ring and the connecting shaft, and is used for maintaining uniform distribution of the balls in the raceways, so that the balls and the two raceway surfaces are uniformly loaded, and the balls can rotate along the central generatrix of the balls when relatively moving on the two raceway surfaces, so that the friction between the contact surfaces in the loading process is rolling friction; relative rotation between the upper connecting ring and the lower connecting ring is realized through rolling of the balls; the connecting shaft penetrates through the upper connecting ring and then is fixedly connected with the lower connecting ring. The problem that the design of a traditional rotary joint cannot meet the light and small requirements is solved.

Description

Technical Field

[0001] This invention relates to a bearingless integrated lightweight rotary joint and its design method, belonging to the field of aerospace aerodynamic deceleration. Background Technology

[0002] To ensure the parachute assembly can properly transmit the generated aerodynamic force to the decelerated body, and to eliminate the spin interference between the parachute and the decelerated body, preventing the parachute lines from becoming entangled due to rotation, which would reduce the parachute's drag area and lead to deceleration failure, a rotary joint needs to be installed between the parachute and the decelerated body. Figure 1 As shown.

[0003] A rotary joint is a structural component that allows the upper and lower connecting rings to rotate continuously 360° relative to each other. Through the assembly of different parts, it can transmit loads and perform rotational functions. Generally, the rotational function of a rotary joint is achieved by installing a thrust ball bearing between the upper and lower connecting rings.

[0004] Thrust ball bearings consist of a shaft ring, cage, balls, and housing ring. When the weight and size requirements of a rotary joint are relatively small, the number of bearing options is limited. Rotary joints that achieve de-rotation functionality through adapter bearings are difficult to design for small and lightweight rotary joints. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and solve the problem that the traditional rotary joint design cannot meet the requirements of light and small size.

[0006] The objective of this invention is achieved through the following technical solutions:

[0007] In a first aspect, the present invention provides a bearingless integrated lightweight rotary joint, comprising an upper connecting ring, a connecting shaft, a cage, balls, and a lower connecting ring;

[0008] The upper connecting ring has raceways, providing a raceway surface for the circumferential rolling of the balls; the connecting shaft has raceways, providing another raceway surface for the circumferential rolling of the balls; the cage is located between the upper connecting ring and the connecting shaft to maintain the uniform distribution of the balls in the raceways, ensuring uniform load distribution on the balls and the two raceway surfaces. When the balls have relative movement between the two raceway surfaces, they can rotate along their central generatrix, thus making the friction between the contact surfaces during the load-bearing process rolling friction; the relative rotation between the upper and lower connecting rings is achieved through the rolling of the balls; the connecting shaft passes through the upper connecting ring and is fixedly connected to the lower connecting ring.

[0009] Based on the first aspect, in one embodiment of the present invention, a set screw is also included, and the lower connecting ring and the connecting shaft are fixedly connected by the set screw to prevent the threads from loosening.

[0010] Based on the first aspect, in one embodiment of the present invention, the cage is in a suspended state when in operation, and has no contact with the connecting shaft or the upper connecting ring.

[0011] Based on the first aspect, in one embodiment of the present invention, the circular hole on the cage for accommodating the ball is a window or a pocket.

[0012] Secondly, the present invention provides a design method for a bearingless integrated lightweight rotary joint, comprising:

[0013] 1) Based on the load-bearing capacity and dimensional requirements of the rotary joint, design the overall shape and component composition of the rotary joint and select the materials for each component;

[0014] 2) Based on the overall shape and load-bearing capacity of the rotary joint, select and design the standard ball bearings and quantity, while also considering the feasibility of the cage manufacturing process;

[0015] 3) The cage design should be based on the size and number of balls. The cage design should take into account the raceway depth on the upper connecting ring and the connecting shaft, as well as the clearance between the cage and the mating surfaces of the connecting shaft and the upper connecting ring.

[0016] 4) Based on the load-bearing capacity and size limitations of the rotary joint, the shape and raceway of the connecting shaft are designed, and the axial direction of the connecting shaft and the cage is a clearance fit;

[0017] 5) Based on the load-bearing capacity and size limitations of the rotary joint, design the shape of the upper connecting ring and the raceway;

[0018] 6) Design the shape of the lower connecting ring according to the load-bearing capacity and size limitations of the rotary joint;

[0019] 7) Set a set screw at the threaded connection between the lower connecting ring and the connecting shaft to prevent the threads from loosening.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] (1) Under the condition of meeting the strength requirements, the lightweight design of the rotary joint of the present invention can reduce the mass concentration point of the entire parachute system, which is conducive to the parachute being pulled out of the parachute pack smoothly, straightened and inflated, and improving the reliability of the parachute opening.

[0022] (2) When the parachute packaging volume is small or the packaging volume is irregular, the present invention can be applied to the harsh conditions of packaging space by designing a lightweight and small-volume rotary joint.

[0023] (3) This invention uses a combination of ball bearings, upper connecting ring, and raceway of connecting shaft to form a rotating pair structure, thereby achieving a rotary joint design with rotating function; by designing the bearing and rotary joint body as an integrated unit, the rotary joint is made lightweight. At the same time, this design method is also applicable to rotary joints of other specifications.

[0024] (4) Compared with traditional methods, the present invention eliminates the bearing shaft ring and seat ring, reduces the weight and size of the rotary joint, breaks the standard bearing's limitation on the size of the rotary joint, reduces the number of rotary joint parts, and provides support for the design of lightweight and miniaturized rotary joints.

[0025] (5) The precision requirements of the rotating joint used in the parachute rotary joint are much lower than those of the standard bearing. This invention can achieve the anti-rotation function through structural design, which reduces production costs compared to using bearings. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of a parachute and deceleration chute system.

[0027] Figure 2 This is a schematic diagram of a rotary joint.

[0028] Reference numerals: 1—parachute; 2—rotary joint; 3—connecting belt; 4—decelerated body; 5—upper connecting ring; 6—connecting shaft; 7—cage; 8—ball bearing; 9—set screw; 10—lower connecting ring. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0030] The parachute deceleration system refers to the process where a parachute 1 carrying a suspended object (the decelerated object 4) descends slowly from the air. Relying on the parachute 1's efficient aerodynamic deceleration capability, it reduces the descent speed of the decelerated object 4 to achieve mission requirements. In the actual deceleration process, the airflow affects the parachute 1, causing uneven tangential forces on either the parachute 1 or the decelerated object 4, resulting in spin. To prevent asynchronous spin between the parachute 1 and the decelerated object 4, which could lead to the parachute lines becoming entangled due to twisting, reducing the drag area of ​​the parachute 1, and ultimately causing deceleration failure, a swivel joint 2 is installed between the parachute 1 and the decelerated object 4. The swivel joint 2 is connected to the parachute 1 via its lines and to the decelerated object 4 via a connecting belt 3.

[0031] The upper connecting ring is the component that connects the rotary joint to the paracord, and the lower connecting ring is the component that connects to the connecting belt. The upper and lower connecting rings are connected by a connecting shaft. To achieve continuous 360° rotation of the upper and lower connecting rings relative to each other, a bearing structure or the rotary joint of this invention is required. The rotary joint of this invention achieves the function of a bearing seat ring and shaft ring by machining grooves on the connecting shaft and the upper connecting ring, retaining the traditional bearing ball and cage structure. The rolling rotation of the upper and lower connecting rings is achieved by the balls, reducing rotational friction. The cage's function is to keep the balls evenly distributed within the grooves. To prevent the connecting threads between the connecting shaft and the lower connecting ring from loosening when the upper and lower connecting rings rotate relative to each other, a set screw is installed at the connection between the lower connecting ring and the connecting shaft after assembly to secure the connecting shaft and the lower connecting ring.

[0032] A bearingless integrated lightweight rotary joint achieves the function of a rotary pair by designing arc-shaped raceway grooves on the corresponding end faces of the connecting shaft 6 and the lower connecting ring 10, selecting appropriate balls 8, and designing a cage 7.

[0033] The cage 7 design of this invention ensures that all balls 8 are subjected to uniform force on the same plane; the circular hole design of the cage 7 ensures even distribution of balls and prevents ball aggregation; the rigid design of the cage 7 facilitates synchronous rolling of each ball 8 and prevents jamming of the rotating joint. This rotary joint design uses a minimum of 4 balls 8 to ensure good rotational function, and the destructive load of the balls 8 must be greater than the operating load. The upper connecting ring 5 and connecting shaft 6 of this invention require grooved raceways for rolling contact with the balls 8. The radius of curvature and depth of the grooved raceways must be designed to match the balls 8. The material used for the grooved raceways should be a high-hardness material to prevent indentations from being pressed into the balls 8 under stress, thus hindering ball rotation. The materials of each component must undergo stress verification to ensure that the load-bearing requirements are met.

[0034] A bearingless, integrated, lightweight rotary joint, such as Figure 2 As shown, it includes an upper connecting ring 5, a connecting shaft 6, a retainer 7, a ball bearing 8, a set screw 9, and a lower connecting ring 10.

[0035] The upper connecting ring 5 has raceways, providing a path for the circumferential rolling of the balls 8 (i.e., the lower raceway surface); the connecting shaft 6 also has raceways, providing a path for the circumferential rolling of the balls 8 (i.e., the upper raceway surface); the cage 7 is located between the upper connecting ring 5 and the connecting shaft 6, used to maintain the uniform distribution of the balls 8 in the raceways, ensuring uniform load distribution on the balls 8 and the upper and lower raceway surfaces. When the balls 8 have relative movement on the upper and lower raceway surfaces, they can rotate along their central generatrix, thus minimizing the friction between the contact surfaces during the load-bearing process to rolling friction; the relative rotation between the upper connecting ring 5 and the lower connecting ring 10 is achieved through the rolling of the balls 8; the connecting shaft 6 passes through the upper connecting ring 5 and is fixed to the lower connecting ring 10 by threads. The lower connecting ring 10 is fixed to the connecting shaft 6 by set screws 9 to prevent the threads from loosening.

[0036] A bearingless, integrated, lightweight rotary joint design method includes:

[0037] 1) Based on the load-bearing capacity and dimensional requirements of the rotary joint, design the overall shape and component composition of the rotary joint and select the materials for each component;

[0038] 2) Based on the overall shape and load-bearing capacity of the rotary joint, select and design the standard ball bearings and quantity, while also considering the feasibility of the cage manufacturing process;

[0039] 3) The cage 7 is designed according to the size and quantity of the balls 8. The design of the cage 7 must consider the raceway depth on the upper connecting ring 5 and the connecting shaft 6, as well as the clearance between the cage 7 and the mating surfaces of the connecting shaft 6 and the upper connecting ring 5. The cage 7 design should consider that the cage is suspended in the working state of the rotary joint, that is, it has no contact with the connecting shaft 6 and the upper connecting ring 5. To achieve this function, the circular hole design of the cage 7 is usually designed as a window (the cross-section is a door-shaped opening at the top) or a pocket (the cross-section is bracket-shaped). When the circular hole is a window, attention should be paid to the installation direction of the cage 7 to ensure that the cage 7 is locked on the balls 8 and does not fall off during actual use; when the circular hole is a pocket, it should be ensured that the maximum diameter cross-section of the balls 8 and the central axis of the pocket are on the same plane.

[0040] 4) Based on the load-bearing capacity and size limitations of the rotary joint, the shape and raceway design of the connecting shaft 6 are carried out. The connecting shaft 6 and the cage 7 are axially clearance fit. The shaft diameter of the connecting shaft 6 should be smaller than the inner diameter of the cage 7 structure. The raceway design of the lower end face of the connecting shaft 6 needs to consider the rolling fit with the balls 8. Its core design parameters are the groove curvature radius coefficient (between 0.56 and 0.58 is more suitable) and the raceway depth coefficient (greater than 0.1).

[0041] 5) Based on the load-bearing capacity and size limitations of the rotary joint, design the shape and raceway of the upper connecting ring 5;

[0042] 6) Design the shape of the lower connecting ring 10 according to the load-bearing capacity and size limitations of the rotary joint;

[0043] 7) Set a set screw 9 at the threaded connection between the lower connecting ring 10 and the connecting shaft 6 to secure them together and prevent the threads from loosening;

[0044] 8) The dimensional fit between each part must be considered during the design of each part. After the preliminary design is completed, the strength of each part of the rotary joint shall be checked.

[0045] 9) Perform overall strength verification on the rotary joint, and iterate the design of dimensions and materials for areas with insufficient strength until the requirements are met.

[0046] The contents not described in detail in this specification are common knowledge to those skilled in the art.

[0047] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A bearingless, integrated, lightweight rotary joint, characterized in that, Includes an upper connecting ring (5), a connecting shaft (6), a cage (7), balls (8), and a lower connecting ring (10); The upper connecting ring (5) has a raceway, which provides a raceway surface for the circumferential rolling of the ball (8); the connecting shaft (6) has a raceway, which provides another raceway surface for the circumferential rolling of the ball (8); the cage (7) is located between the upper connecting ring (5) and the connecting shaft (6) to maintain the uniform distribution of the ball (8) in the raceway, so that the ball (8) and the two raceway surfaces bear uniform load. When the ball (8) has relative movement between the two raceway surfaces, it can rotate along its central generatrix, so that the friction between the contact surfaces during the bearing process is rolling friction; the relative rotation between the upper connecting ring (5) and the lower connecting ring (10) is realized by the rolling of the ball (8); the connecting shaft (6) passes through the upper connecting ring (5) and is fixedly connected to the lower connecting ring (10).

2. The bearingless integrated lightweight rotary joint according to claim 1, characterized in that, It also includes a set screw (9), and the lower connecting ring (10) and the connecting shaft (6) are fixed together by the set screw (9) to prevent the threads from loosening.

3. The bearingless integrated lightweight rotary joint according to claim 1, characterized in that, The cage (7) is suspended in the working state and has no contact with the connecting shaft (6) or the upper connecting ring (5).

4. The bearingless integrated lightweight rotary joint according to claim 1, characterized in that, The round hole on the cage (7) that houses the ball (8) is a window or pocket.

5. The design method of the bearingless integrated lightweight rotary joint according to claim 1, characterized in that, include: 1) Based on the load-bearing capacity and size requirements of the rotary joint (2), design the overall shape and component composition of the rotary joint (2) and select the materials for each component; 2) Based on the overall shape and load-bearing capacity of the rotary joint (2), the selection and quantity design of standard balls (8) should be carried out, and the process feasibility of the cage (7) should also be considered. 3) Design the cage (7) according to the size and number of balls (8). The design of the cage (7) must take into account the raceway depth on the upper connecting ring (5) and the connecting shaft (6), as well as the clearance between the mating surfaces of the connecting shaft (6) and the upper connecting ring (5). 4) Based on the load-bearing capacity and size limitations of the rotary joint (2), the shape and raceway of the connecting shaft (6) are designed, and the axial direction of the connecting shaft (6) and the cage (7) is a clearance fit; 5) Based on the load-bearing capacity and size limitations of the rotary joint (2), design the shape and raceway of the upper connecting ring (5); 6) Based on the load-bearing capacity and size limitations of the rotary joint (2), the shape of the lower connecting ring (10) is designed; 7) Set a set screw (9) at the threaded connection between the lower connecting ring (10) and the connecting shaft (6) to secure them together and prevent the threads from loosening.

6. The bearingless integrated lightweight rotary joint design method according to claim 5, characterized in that, In step 3), the retainer (7) is in a suspended state when in operation, that is, it is not in contact with the connecting shaft (6) or the upper connecting ring (5); the round hole of the retainer (7) is designed as a window or pocket.

7. The bearingless integrated lightweight rotary joint design method according to claim 6, characterized in that, When the round hole is a pocket, the maximum diameter section of the ball (8) should be on the same plane as the central axis of the pocket; when the round hole is a window, attention should be paid to the installation direction of the retainer (7) to ensure that the retainer (7) is stuck on the ball (8) and does not fall off during actual use.

8. The bearingless integrated lightweight rotary joint design method according to claim 5, characterized in that, In step 4), the diameter of the connecting shaft (6) should be smaller than the inner diameter of the cage (7) structure. The raceway design of the lower end face of the connecting shaft (6) needs to consider the rolling fit with the ball (8). The groove curvature radius coefficient is 0.56 to 0.58, and the raceway depth coefficient is greater than 0.

1.

9. The bearingless integrated lightweight rotary joint design method according to claim 5, characterized in that, Step 7) is followed by: 8) After the preliminary design is completed, the strength of each part of the rotary joint (2) is checked; 9) Perform strength verification on the rotary joint (2) as a whole, and iteratively design and select the size and material for the parts with insufficient strength until the requirements are met.

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