A planetary roller screw with equal load distribution

Abstract

The present invention relates to the technical field of planetary roller screws, and discloses an equal load distribution planetary roller screw, comprising an equal pitch screw, a plurality of gradient pitch rollers uniformly distributed along the center line of the equal pitch screw, and a gradient pitch nut arranged on the outer layer of the gradient pitch roller; the outer thread of the equal pitch screw is meshed with the inner outer thread of the gradient pitch roller, the outer outer thread of the gradient pitch roller is meshed with the inner thread of the gradient pitch nut, and the gear teeth at both ends of the gradient pitch roller are meshed with the inner gear rings at both ends of the gradient pitch nut; the load distribution coefficient of the equal pitch screw and the gradient pitch roller side is equal to the load distribution coefficient of the gradient pitch roller and the gradient pitch nut side. The present invention adjusts the coordination relationship of thread tooth deformation through a new gradient pitch roller and gradient pitch nut design, and realizes an equal load distribution design in which the load distribution coefficients of the nut-roller and roller-screw sides are both 1.

Description

Technical Field

[0001] The invention relates to the technical field of planetary roller screws, and in particular to an equal load distribution planetary roller screw. Background Art

[0002] The planetary roller screw is composed of a screw, uniformly distributed rollers, a nut and a planetary carrier. The rollers realize the conversion between linear and rotational motion between the screw and the nut through the threads and the gear teeth at both ends in the form of revolution and rotation. The planetary roller screw has a large contact curvature radius and many contact points, which enables it to bear a large load. The design of small pitch and large lead ensures its high transmission accuracy, while it is easy to achieve light weight and small size. Compared with ball screws, planetary roller screws have obvious advantages in load capacity, positioning accuracy, life and volume. Therefore, planetary roller screws are widely used in aerospace, precision machine tools, robots, medical equipment and automation equipment.

[0003] Planetary roller screws transmit motion and power through the threaded meshing of screws, rollers and nuts, which is a multi-point non-coordinated contact, resulting in uneven load distribution on the threads. Uneven load distribution on the threads leads to excessive loads on some contact points, and the meshing interface is prone to wear, bonding, lubrication and contact fatigue failure, which seriously affects the service performance of the planetary roller screw. In addition, the maximum load of the planetary roller screw depends on the contact characteristics of all threads, especially the maximum contact load in the thread. It can be seen that uneven load distribution will seriously limit the increase in the maximum load of the planetary roller screw. For this reason, it is of great significance to design the planetary roller screw with uniform or even equal load distribution.

[0004] However, the current uniform load distribution design for planetary roller screws still cannot achieve an equal load distribution design with a load distribution coefficient of 1, and the design method is relatively complicated and cumbersome. In addition, the current uniform load distribution designs for the roller-screw side and the nut-roller side of the planetary roller screw are mostly separate. Therefore, it is of great practical application value to develop a planetary roller screw with equal load distribution on the nut-roller and roller-screw sides. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides a planetary roller screw with equal load distribution.

[0006] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0007] An equal load distribution planetary roller screw, comprising:

[0008] An equal pitch lead screw, a plurality of gradient pitch rollers evenly distributed along the center line of the equal pitch lead screw, and gradient pitch nuts arranged on the outer layer of the gradient pitch rollers;

[0009] The outer thread of the equal pitch lead screw is meshed with the inner outer thread of the gradual pitch roller, the outer outer thread of the gradual pitch roller is meshed with the inner thread of the gradual pitch nut, and the gear teeth at both ends of the gradual pitch roller are meshed with the inner gear rings at both ends of the gradual pitch nut;

[0010] The load distribution coefficient of the contact side between the equal pitch lead screw and the gradually pitched roller is equal to the load distribution coefficient of the contact side between the gradually pitched roller and the gradually pitched nut.

[0011] In a possible implementation, the load distribution coefficient between the equal-pitch screw and the gradually-pitch roller side and the load distribution coefficient between the gradually-pitch roller and the gradually-pitch nut side are both 1.

[0012] In a possible implementation, a plurality of gradually variable pitch rollers are evenly separated by planet carriers disposed at both ends; the planet carrier is fixed by an outermost elastic retaining ring.

[0013] In a possible implementation, the design method for making the load distribution coefficient between the equal pitch lead screw and the variable pitch roller side equal to the load distribution coefficient between the variable pitch roller and the variable pitch nut side includes:

[0014] According to the design requirements of equal load distribution, that is, the load distribution coefficients of the planetary roller screw with gradual pitch roller and gradual pitch nut side and the equal pitch screw and gradual pitch roller side are equal and 1, the equal load distribution force matrix is ​​derived;

[0015] According to the deformation coordination relationship between the two adjacent threads on the side of the variable pitch roller and the variable pitch nut and the side of the equal pitch screw and the variable pitch roller, the corresponding deformation coordination equations are established respectively, and the load distribution calculation model of the planetary roller screw thread teeth is established by combining the balance equations of the axial contact load and the external load on the side of the variable pitch roller and the gradual pitch nut and the side of the equal pitch screw and the gradual pitch roller.

[0016] According to the planetary roller screw thread load distribution calculation model and the equal load distribution force matrix, the pitch design parameters of the variable pitch nut and the variable pitch roller are solved.

[0017] By designing and manufacturing the variable pitch nut and the variable pitch roller according to the solved pitch design parameters, an equal load distribution planetary roller screw with equal load distribution coefficients between the variable pitch roller and the variable pitch nut side and between the equal pitch screw and the gradual pitch roller side can be obtained.

[0018] In a possible implementation, the equal load distribution force matrix is ​​specifically:

[0019] F = [ F NR1 ; F NR2 ; ⋯ F NR( n -1) ; F NR n ; F RS( n + 1 ) ; F RS( n +2) ; ⋯ F RS(2 n -1) ; F RS(2 n ) ] = [ 1 ; 1 ; ⋯ 1 ; 1 ] 2 n × 1 ⋅ ( F 0 nz ) ;

[0020] Where F represents the equal load distribution force matrix, F NR represents the axial contact load between the variable pitch roller and the variable pitch nut side, F RS represents the axial contact load between the equal pitch screw and the variable pitch roller side, n represents the number of threads of the variable pitch roller, z represents the number of variable pitch rollers, F0 represents the external load, [1;1;···1;1] 2n×1 represents the equal load distribution coefficient matrix.

[0021] In a possible implementation, the deformation coordination equation of the gradient pitch roller and the gradient pitch nut side is specifically:

[0022] ;

[0023] Among them, P N and P R Respectively represent the pitch between adjacent threads of the variable pitch nut and the variable pitch roller, F NR represents the axial contact load between the variable pitch roller and the variable pitch nut side, F RS represents the axial contact load between the equal pitch screw and the variable pitch roller side, k NT and k RT They represent the thread stiffness of the variable pitch nut and the variable pitch roller, respectively, k NA and k RA They represent the shaft segment stiffness of the variable pitch nut and the variable pitch roller, respectively, k NRC It represents the axial contact stiffness of the contact side between the variable pitch roller and the variable pitch nut, and i and j represent the thread numbers.

[0024] In a possible implementation, the deformation coordination equation of the equal pitch lead screw and the gradually variable pitch roller side is specifically:

[0025] ;

[0026] Among them, P R and P S Respectively represent the pitch between adjacent threads of the variable pitch roller and the equal pitch lead screw, F NR represents the axial contact load between the variable pitch roller and the variable pitch nut side, F RS represents the axial contact load between the equal pitch screw and the variable pitch roller side, n represents the number of threads of the variable pitch roller, k RT and k ST They represent the thread stiffness of the variable pitch roller and the equal pitch screw, respectively, k RA and k SA They represent the shaft segment stiffness of the variable pitch roller and the equal pitch screw, respectively, k RSCIt represents the axial contact stiffness between the equal pitch screw and the variable pitch roller side, where i and j represent the thread numbers.

[0027] In a possible implementation, the balance equations of the axial contact loads on the variable pitch roller and the variable pitch nut side and the equal pitch lead screw and the variable pitch roller side and the external loads are specifically:

[0028] ;

[0029] Wherein, F represents the equal load distribution force matrix, n represents the number of thread teeth of the variable pitch roller, z represents the number of variable pitch rollers, and F0 represents the external load.

[0030] In a possible implementation, the planetary roller screw thread load distribution calculation model is specifically:

[0031] { B 2 n × 2 n ⋅ F 2 n × 1 = X 2 n × 1 X 2 n × 1 = [ P R 1 − P N 1 ; P R 2 − P N 2 ; ⋯ P R ( n − 1 ) − P N ( n − 1 ) ; P R 1 − P S ; P R 2 − P S ; ⋯ ; P R ( n − 1 ) − P S ; F 0 z ; F 0 z ] ;

[0032] Among them, B 2n×2n represents the matrix composed of stiffness, F 2n×1 represents the equal load distribution force matrix, P N , P R and P S They represent the pitch between adjacent threads of the variable pitch nut, variable pitch roller and equal pitch screw respectively, n represents the number of threads of the variable pitch roller, z represents the number of variable pitch rollers, and F0 represents the external load.

[0033] In a possible implementation, the method for designing and manufacturing a variable pitch nut and a variable pitch roller according to the pitch design parameters obtained by the solution includes:

[0034] Taking the minimum pitch value of the gradual pitch nut and the gradual pitch roller as the fixed pitch, the gradual pitch nut and the gradual pitch roller are processed to obtain the initial processed parts;

[0035] According to the solved pitch design parameters, the thread pitches of the initial machined parts of the variable pitch nut and the variable pitch roller are modified respectively to obtain a planetary roller screw with equal load distribution.

[0036] The present invention has the following beneficial effects:

[0037] 1) The present invention can realize an equal load distribution design in which the load distribution coefficients of the variable pitch roller and the variable pitch nut side and the equal pitch screw and the variable pitch roller side are both 1, thereby realizing the maximum load performance improvement of the planetary roller screw.

[0038] 2) The planetary roller screw equal load distribution design method proposed in the present invention is simple and easy to implement, and this method belongs to the forward design method. In addition to equal load distribution, the planetary roller screw design with other load distribution can also be realized as needed.

[0039] 3) The present invention performs thread shaping on the initial processed parts of the gradient pitch roller and the gradient pitch nut to meet the required gradient pitch design requirements, and the processing and manufacturing process is reasonable and easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A schematic diagram of the structure of an equal load distribution planetary roller screw;

[0041] Figure 2 Flowchart of design method for equal load distribution planetary roller screw;

[0042] Figure 3 Schematic diagram of forces and numbers of planetary roller screws for equal load distribution;

[0043] Figure 4 It is a schematic diagram of gradual pitch modification;

[0044] Figure 5 The roller and nut gradient pitch diagram obtained by the load distribution design method for planetary roller screws;

[0045] Figure 6 Design verification of equal load distribution planetary roller screw and comparison of load distribution coefficient with traditional planetary roller screw.

[0046] The accompanying drawings are marked as follows: 1-gradient pitch nut; 2-equal pitch screw; 3-gradient pitch roller; 4-inner gear ring; 5-planet carrier; 6-elastic retaining ring. DETAILED DESCRIPTION

[0047] The specific implementation modes of the present invention are described below to facilitate those skilled in the art to understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0048] like Figure 1 As shown, an embodiment of the present invention provides an equal load distribution planetary roller screw, comprising:

[0049] An equal pitch screw 2, a plurality of gradually pitched rollers 3 evenly distributed along the center line of the equal pitch screw 2, and a gradually pitched nut 1 arranged on the outer layer of the gradually pitched rollers 3;

[0050] The outer thread of the equal pitch screw 2 is meshed with the inner outer thread of the gradual pitch roller 3, the outer outer thread of the gradual pitch roller 3 is meshed with the inner thread of the gradual pitch nut 1, and the gear teeth at both ends of the gradual pitch roller 3 are meshed with the inner gear ring 4 at both ends of the gradual pitch nut 1;

[0051] The load distribution coefficient between the equal pitch screw 2 and the gradually pitched roller 3 is equal to the load distribution coefficient between the gradually pitched roller 3 and the gradually pitched nut 1 .

[0052] The center of the equal load distribution planetary roller screw of the present invention is an equal pitch screw 2, and a plurality of gradually variable pitch rollers 3 are evenly distributed along the center line of the equal pitch screw 2. The equal pitch screw 2 and the gradually variable pitch rollers 3 are both external threads, and the outermost layer is an internally threaded gradually variable pitch nut 1. The equal pitch screw 2 is meshed with the inner thread of the gradually variable pitch roller 3, and the gradually variable pitch nut 1 is meshed with the outer thread of the gradually variable pitch roller 3. The gear teeth at both ends of the gradually variable pitch roller 3 are meshed with the inner gear ring 4 fixed at both ends of the gradually variable pitch nut 1. The gradually variable pitch roller 3 is evenly separated by the planet carrier 5 at both ends, and the planet carrier 5 is fixed by the outermost elastic retaining ring 6 so that there is no axial relative displacement between it and the gradually variable pitch nut 1. The present invention realizes the conversion of the linear and rotational motions of the equal pitch screw 2 and the gradually variable pitch nut 1 through the rotation and revolution of the evenly distributed gradually variable pitch rollers 3. The equal load distribution planetary roller screw of the present invention adjusts the coordination relationship of thread deformation through a new design of a gradual pitch roller 3 and a gradual pitch nut 1, thereby realizing an equal load distribution design in which the load distribution coefficients on the side of the equal pitch screw 2 and the gradual pitch roller 3 and the load distribution coefficients on the side of the gradual pitch roller 3 and the gradual pitch nut 1 are both 1.

[0053] In an optional embodiment of the present invention, the design method for making the load distribution coefficient between the equal pitch screw 2 and the gradual pitch roller 3 side equal to the load distribution coefficient between the gradual pitch roller 3 and the gradual pitch nut 1 side includes the following steps S1 to S4:

[0054] S1. According to the design requirement of equal load distribution, that is, the load distribution coefficients on the side of the planetary roller screw with gradual pitch roller 3 and gradual pitch nut 1 and on the side of the equal pitch screw 2 and gradual pitch roller 3 are equal and 1, and the equal load distribution force matrix is ​​derived;

[0055] S2. According to the deformation coordination relationship between the two adjacent threads on the side of the gradual pitch roller 3 and the gradual pitch nut 1 and the side of the equal pitch screw 2 and the gradual pitch roller 3, the corresponding deformation coordination equations are established respectively, and the load distribution calculation model of the planetary roller screw thread teeth is established in combination with the balance equations of the load and external load on the side of the gradual pitch roller 3 and the gradual pitch nut 1 and the side of the equal pitch screw 2 and the gradual pitch roller 3;

[0056] S3, according to the planetary roller screw thread load distribution calculation model and the equal load distribution force matrix, solve and obtain the pitch design parameters of the gradual pitch nut 1 and the gradual pitch roller 3;

[0057] S4. Design and manufacture the variable pitch roller 3 and the variable pitch nut 1 according to the pitch design parameters of the variable pitch nut 1 and the variable pitch roller 3, and obtain an equal load distribution planetary roller screw with equal load distribution coefficients on the variable pitch roller 3 and the variable pitch nut 1 side and on the equal pitch screw 2 and the gradual pitch roller 3 side.

[0058] like Figure 2 As shown, the present invention first establishes a planetary roller screw thread load distribution calculation model according to the deformation coordination relationship between the variable pitch roller 3 and the variable pitch nut 1 side and the equal pitch screw 2 and the variable pitch roller 3 side, as well as the load balance condition; then the equal load distribution coefficient is used as the input parameter of the planetary roller screw thread load distribution calculation model, and the pitch design parameters of the equal load planetary roller screw variable pitch nut 1 and the variable pitch roller 3 are obtained by solving the planetary roller screw thread load distribution calculation model; finally, the obtained pitch design parameters are used for the design and processing of the variable pitch nut 1 and the variable pitch roller 3, so as to achieve a substantial improvement in the load performance of the planetary roller screw.

[0059] The equal load distribution design method of the planetary roller screw proposed in the present invention adopts the positive design method and takes the equal load distribution coefficient as the input parameter to solve the gradient pitch design parameters of the gradient pitch roller 3 and the gradient pitch nut 1, and applies the pitch design parameters to the design and processing of the gradient pitch roller 3 and the gradient pitch nut 1, so as to realize the equal load distribution of the equal pitch screw 2 and the gradient pitch roller 3 side and the gradient pitch roller 3 and the gradient pitch nut 1 side of the planetary roller screw. The present invention can realize the equal load distribution design in which the load distribution coefficients of the equal pitch screw 2 and the gradient pitch roller 3 side and the gradient pitch roller 3 and the gradient pitch nut 1 side are both 1, so as to realize the maximum load performance improvement of the planetary roller screw.

[0060] In an optional embodiment of the present invention, step S1 first determines the given design parameters and the parameters to be designed of the planetary roller screw, sets the pitch of the variable pitch nut 1 and the variable pitch roller 3 as the parameters to be designed, and the remaining parameters are all known given values. Since the variable pitch roller 3 and the variable pitch nut 1 side and the equal pitch screw 2 and the variable pitch roller 3 side are in equal load contact, the load distribution coefficient is 1. Therefore, the equal load distribution force matrix can be derived as follows:

[0061] F = [ F NR1 ; F NR2 ; ⋯ F NR( n -1) ; F NR n ; F RS( n + 1 ) ; F RS( n +2) ; ⋯ F RS(2 n -1) ; F RS(2 n ) ] = [ 1 ; 1 ; ⋯ 1 ; 1 ] 2 n × 1 ⋅ ( F 0 nz ) ;

[0062] Where F represents the equal load distribution force matrix, F NRrepresents the axial contact load between the variable pitch roller 3 and the variable pitch nut 1, F RS It represents the axial contact load between the equal pitch screw 2 and the variable pitch roller 3. The subscript is the corresponding thread number. The numbering method is as follows: Figure 3 As shown; n represents the number of threads of the variable pitch roller 3, z represents the number of the variable pitch roller 3, F0 represents the external load, [1;1;···1;1] 2n×1 represents the equal load distribution coefficient matrix.

[0063] In an optional embodiment of the present invention, step S2 derives 2n-2 deformation coordination equations according to the deformation coordination relationship between the two adjacent threads of the gradual pitch roller 3 and the gradual pitch nut 1 side and the equal pitch lead screw 2 and the gradual pitch roller 3 side; the deformation coordination equation of the gradual pitch roller 3 and the gradual pitch nut 1 side is specifically:

[0064] ;

[0065] Among them, P N and P R They represent the pitch between adjacent threads of the variable pitch nut 1 and the variable pitch roller 3, respectively. NR represents the axial contact load between the variable pitch roller 3 and the variable pitch nut 1, F RS represents the axial contact load between the equal pitch screw 2 and the variable pitch roller 3, k NT and k RT They represent the thread stiffness of the variable pitch nut 1 and the variable pitch roller 3, k NA and k RA They represent the shaft segment stiffness of the variable pitch nut 1 and the variable pitch roller 3, respectively, k NRC represents the axial contact stiffness between the variable pitch roller 3 and the variable pitch nut 1, and i and j represent the thread numbers.

[0066] The deformation coordination equation of the equal pitch screw 2 and the gradually variable pitch roller 3 is specifically:

[0067] ;

[0068] Among them, P R and P S They represent the pitch between adjacent threads of the variable pitch roller 3 and the equal pitch lead screw 2, respectively. NR represents the axial contact load between the variable pitch roller 3 and the variable pitch nut 1, F RS represents the axial contact load between the equal pitch screw 2 and the variable pitch roller 3, n represents the number of threads of the variable pitch roller 3, k RT and k STThey represent the thread stiffness of the variable pitch roller 3 and the equal pitch screw 2, k RA and k SA They represent the shaft segment stiffness of the variable pitch roller 3 and the equal pitch screw 2, k RSC It represents the axial contact stiffness between the equal pitch screw 2 and the variable pitch roller 3, and i and j represent the thread numbers.

[0069] In addition, the balance equations of the loads on the side of the gradual pitch roller 3 and the gradual pitch nut 1 and the side of the equal pitch screw 2 and the gradual pitch roller 3 and the external load are specifically:

[0070] ;

[0071] Wherein, F represents the equal load distribution force matrix, n represents the number of threads of the variable pitch roller 3, z represents the number of the variable pitch roller 3, and F0 represents the external load.

[0072] According to the given design parameters of the planetary roller screw, the axial contact stiffness determined by the thread stiffness, shaft segment stiffness and load is obtained by the corresponding formula.

[0073] The deformation coordination equation and the equilibrium equation are combined and converted into matrix form, and finally the planetary roller screw thread load distribution calculation model is established, which is expressed as:

[0074] { B 2 n × 2 n ⋅ F 2 n × 1 = X 2 n × 1 X 2 n × 1 = [ P R 1 − P N 1 ; P R 2 − P N 2 ; ⋯ P R ( n − 1 ) − P N ( n − 1 ) ; P R 1 − P S ; P R 2 − P S ; ⋯ ; P R ( n − 1 ) − P S ; F 0 z ; F 0 z ] ;

[0075] Among them, B 2n×2n represents the matrix composed of stiffness, F 2n×1 represents the equal load distribution force matrix, P N , P R and P S They respectively represent the pitches between adjacent threads of the variable pitch nut 1 , the variable pitch roller 3 and the equal pitch screw 2 , n represents the number of threads of the variable pitch roller 3 , z represents the number of the variable pitch roller 3 , and F0 represents the external load.

[0076] In an optional embodiment of the present invention, step S3 substitutes the equal load distribution force matrix F into the planetary roller screw thread load distribution calculation model. Since the pitch P of the equal pitch screw 2 is S is a known value. At this time, the planetary roller screw thread load distribution calculation model only contains the unknown number P Ri and P Ni, i∈[1,n-1]. The total number of unknowns is 2n-2, which is less than the number of equations 2n in the planetary roller screw thread load distribution calculation model, and has a unique solution. Solving the planetary roller screw thread load distribution calculation model, we can finally obtain the pitch value P of the i-th pair of threads (thread i and thread i+1) of the variable pitch roller 3 and the variable pitch nut 1. Ri and P Ni , i∈[1,n-1].

[0077] In an optional embodiment of the present invention, step S4 calculates the pitch value P of the gradual pitch roller 3 and the gradual pitch nut 1. Ri and P Ni ,i∈[1,n-1] is used for the design and manufacturing of variable pitch rollers and variable pitch nuts of planetary roller screws. The specific manufacturing of equal load distribution planetary roller screws is as follows: min(P Ri ) and min(P Ni ), i∈[1,n-1], i.e., the minimum pitch of the gradient pitch roller 3 and the gradient pitch nut 1 calculated, is the initial workpiece of the roller and nut obtained by fixed pitch processing. According to the gradient pitch values ​​of the gradient pitch roller 3 and the gradient pitch nut 1 obtained in step S3, the pitch of the i-th thread pair of the initial workpiece of the gradient pitch roller 3 and the gradient pitch nut 1 is modified respectively. The gradient pitch modification method is as follows: Figure 4 As shown, a planetary roller screw that satisfies equal load distribution can be manufactured in the end.

[0078] The present invention realizes the design and processing of an equal load distribution planetary roller screw through the above steps. The equal load distribution planetary roller screw includes a variable pitch nut 1, an equal pitch screw 2, a variable pitch roller 3, an inner gear ring 4, a planet carrier 5 and an elastic retaining ring 6, wherein the variable pitch values ​​of the variable pitch nut 1 and the variable pitch roller 3 are obtained by the proposed equal load distribution design method. The present invention adopts a planetary roller screw equal load distribution design method, wherein the variable pitch values ​​of the variable pitch roller 3 and the variable pitch nut 1 obtained in one embodiment are as follows Figure 5 In order to verify the correctness of the equal load distribution design method, the gradient pitch of the gradient pitch roller 3 and the gradient pitch nut 1 is substituted into the planetary roller screw thread load distribution calculation model, and the load distribution force matrix is ​​solved by the Newton-Raphson method. The load distribution coefficient matrix of the planetary roller screw is further solved according to the load distribution force matrix, as shown in Figure 6 As shown. Figure 6 It can be seen that the load distribution coefficients obtained by solving are all 1, which verifies the correctness of the equal load distribution design method. In addition, the load distribution coefficients of the equal load distribution planetary roller screw of the present invention and the traditional planetary roller screw are compared. Figure 6 As shown, from Figure 6 It can be seen that the load distribution coefficient of the load-distributing planetary roller screw of the present invention is more uniform than that of the traditional planetary roller screw and is 1, so the maximum load performance improvement of the planetary roller screw can be achieved.

[0079] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0080] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0081] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0082] The present invention uses specific embodiments to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

[0083] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific variations and combinations that do not deviate from the essence of the present invention based on the technical revelations disclosed by the present invention, and these variations and combinations are still within the protection scope of the present invention.

Claims

1. An equal load distribution planetary roller screw, characterized in that: include: An equal pitch lead screw, a plurality of gradient pitch rollers evenly distributed along the center line of the equal pitch lead screw, and gradient pitch nuts arranged on the outer layer of the gradient pitch rollers; The outer thread of the equal pitch lead screw is meshed with the inner outer thread of the gradual pitch roller, the outer outer thread of the gradual pitch roller is meshed with the inner thread of the gradual pitch nut, and the gear teeth at both ends of the gradual pitch roller are meshed with the inner gear rings at both ends of the gradual pitch nut; The load distribution coefficient between the equal pitch lead screw and the gradually pitched roller is equal to the load distribution coefficient between the gradually pitched roller and the gradually pitched nut. The design method for making the load distribution coefficient between the equal pitch lead screw and the gradually pitched roller equal to the load distribution coefficient between the gradually pitched roller and the gradually pitched nut comprises: According to the design requirements of equal load distribution, that is, the load distribution coefficients of the planetary roller screw with gradual pitch roller and gradual pitch nut side and the equal pitch screw and gradual pitch roller side are equal and 1, the equal load distribution force matrix is ​​derived; According to the deformation coordination relationship between the two adjacent threads on the side of the variable pitch roller and the variable pitch nut and the side of the equal pitch screw and the variable pitch roller, the corresponding deformation coordination equations are established respectively, and the load distribution calculation model of the planetary roller screw thread teeth is established by combining the balance equations of the axial contact load and the external load on the side of the variable pitch roller and the gradual pitch nut and the side of the equal pitch screw and the gradual pitch roller. According to the planetary roller screw thread load distribution calculation model and the equal load distribution force matrix, the pitch design parameters of the variable pitch nut and the variable pitch roller are solved. By designing and manufacturing the variable pitch nut and the variable pitch roller according to the solved pitch design parameters, an equal load distribution planetary roller screw with equal load distribution coefficients between the variable pitch roller and the variable pitch nut side and between the equal pitch screw and the gradual pitch roller side can be obtained.

2. The equal load distribution planetary roller screw according to claim 1, characterized in that: The load distribution coefficient between the equal pitch screw and the gradually pitched roller side and the load distribution coefficient between the gradually pitched roller and the gradually pitched nut side are both 1.

3. The equal load distribution planetary roller screw according to claim 1, characterized in that: A plurality of rollers with gradually varying pitches are evenly separated by planetary carriers arranged at both ends; the planetary carriers are fixed by elastic retaining rings at the outermost sides.

4. The equal load distribution planetary roller screw according to claim 1, characterized in that: The equal load distribution force matrix is ​​specifically: ； Where F represents the equal load distribution force matrix, F NR represents the axial contact load between the variable pitch roller and the variable pitch nut side, F RS represents the axial contact load between the equal pitch screw and the variable pitch roller side, n represents the number of threads of the variable pitch roller, z represents the number of variable pitch rollers, F0 represents the external load, [1;1;···1;1] 2n×1 represents the equal load distribution coefficient matrix.

5. The equal load distribution planetary roller screw according to claim 1, characterized in that: The deformation coordination equation of the gradient pitch roller and the gradient pitch nut side is specifically: ； Among them, P N and P R Respectively represent the pitch between adjacent threads of the variable pitch nut and the variable pitch roller, F NR represents the axial contact load between the variable pitch roller and the variable pitch nut side, F RS represents the axial contact load between the equal pitch screw and the variable pitch roller side, k NT and k RT They represent the thread stiffness of the variable pitch nut and the variable pitch roller, respectively, k NA and k RA They represent the shaft segment stiffness of the variable pitch nut and the variable pitch roller, respectively, k NRC It represents the axial contact stiffness between the variable pitch roller and the variable pitch nut, and i and j represent the thread numbers.

6. The equal load distribution planetary roller screw according to claim 1, characterized in that: The deformation coordination equation of the equal pitch lead screw and the gradually variable pitch roller side is specifically: ； Among them, P R and P S Respectively represent the pitch between adjacent threads of the variable pitch roller and the equal pitch lead screw, F NR represents the axial contact load between the variable pitch roller and the variable pitch nut side, F RS represents the axial contact load between the equal pitch screw and the variable pitch roller side, n represents the number of threads of the variable pitch roller, k RT and k ST They represent the thread stiffness of the variable pitch roller and the equal pitch screw, respectively, k RA and k SA They represent the shaft segment stiffness of the variable pitch roller and the equal pitch screw, respectively, k RSC It represents the axial contact stiffness between the equal pitch screw and the variable pitch roller side, where i and j represent the thread numbers.

7. The equal load distribution planetary roller screw according to claim 1, characterized in that: The balance equations of the axial contact loads on the side of the variable pitch roller and the variable pitch nut and the side of the equal pitch screw and the variable pitch roller and the external load are specifically: ； Wherein, F represents the equal load distribution force matrix, n represents the number of thread teeth of the variable pitch roller, z represents the number of variable pitch rollers, and F0 represents the external load.

8. The equal load distribution planetary roller screw according to claim 1, characterized in that: The planetary roller screw thread load distribution calculation model is specifically: ； Among them, B 2n×2n represents the matrix composed of stiffness, F 2n×1 represents the equal load distribution force matrix, P N , P R and P S They represent the pitch between adjacent threads of the variable pitch nut, variable pitch roller and equal pitch screw respectively, n represents the number of threads of the variable pitch roller, z represents the number of variable pitch rollers, and F0 represents the external load.

9. The equal load distribution planetary roller screw according to claim 1, characterized in that: The method for designing and manufacturing a gradual pitch nut and a gradual pitch roller according to the pitch design parameters obtained by the solution comprises: Taking the minimum pitch value of the gradual pitch nut and the gradual pitch roller as the fixed pitch, the gradual pitch nut and the gradual pitch roller are processed to obtain the initial processed parts; According to the solved pitch design parameters, the thread pitches of the initial machined parts of the variable pitch nut and the variable pitch roller are modified respectively to obtain a planetary roller screw with equal load distribution.

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