Planetary roller screw

Abstract

A planetary roller screw is used for solving the problem that an existing planetary roller screw is insufficient in structural strength. Comprising a main screw provided with a first external thread, a nut provided with an internal thread, a planetary set provided with a plurality of rollers, and each roller is provided with a second external thread; the spiral directions of the first external thread and the internal thread are opposite, and the spiral directions of the internal thread and the second external thread are the same; based on the fact that the ratio of pitch diameters between the driven parts is the same as the ratio of the spiral line number, the spiral line number of the nut is not equal to the sum of the spiral line number of the main screw and the spiral line number of the two rollers; when the driving part is rotated, the driving part generates relative displacement on the driven parts in the axial direction, and the driven parts do not generate relative displacement in the axial direction. The utility model can maintain the motion precision and improve the structural strength.

Description

Technical Field

[0001] This utility model relates to a linear translation technology, and more particularly to a planetary roller screw. Background Technology

[0002] With the development of industrial technology, especially in the development of electric vehicles and humanoid robots, the use of planetary roller screws for linear translational motion control has the characteristics of being able to withstand high loads, high positioning accuracy, and fast movement speed, and can replace traditional hydraulic mechanisms.

[0003] Please refer to Figure 1 The present invention is a planetary roller screw 9, which consists of a main screw 91 and a nut 92 with several rollers 93 disposed between them. The main screw 91 has a first external thread 911 and the nut 92 has an internal thread 921. The several rollers 93 are identical to each other to form a planetary set, and each of the several rollers 93 has a second external thread 931. The main screw 91 is the driving member and rotates, so that the rollers 93 and the nut 92 move integrally along the axial direction of the main screw 91.

[0004] Based on the existing motion mechanism of the planetary roller screw 9, the main screw 91 or the nut 92 to be rotated is defined as the driving element, and the other of the main screw 91 or the nut 92 that produces linear movement is defined as the driven element. When the main screw 91, the nut 92, and the rollers 93 have a large pitch, the linear movement of the driven element caused by one rotation of the driving element is large, resulting in a high linear movement speed, and each component has a large load-bearing / pressure-bearing capacity. When the main screw 91, the nut 92, and the rollers 93 have a small pitch, the linear movement of the driven element caused by one rotation of the driving element is small, resulting in a low linear movement speed, but the movement can be precisely controlled. However, the load-bearing capacity of each component also decreases as the pitch decreases. Therefore, for applications in electric vehicles and humanoid robots, the existing planetary roller screw 9 cannot simultaneously achieve both precise control of movement and a large load-bearing capacity.

[0005] In addition, a prior art discloses a design rule that limits the number of spiral lines T of the main screw 91. 91 Must be: Number of spiral lines T for roller 93 93 Multiply by the pitch circle diameter D of the main screw 91 91 Excluding the pitch circle diameter D of roller 93 93 That is, the corresponding formula can be expressed as T. 91 = T 93 (D 91 / D 93 ); and simultaneously limit the number of helixes T of nut 92. 92 Must be: the number of helixes T of the main screw 9191 the number of helixes of the two rollers 93 93 , that is, the corresponding formula can be expressed as T 92 = T 91 + 2T 93 .

[0006] In particular, in the limiting conditions proposed by the above design rules, the pitch diameter D 92 of the nut 92 must be equal to the pitch diameter D 91 of the main screw 91 plus the pitch diameter D 93 of the two rollers 93, that is, the corresponding formula can be defined as D 92 = D 91 + 2D 93 , thus it can be deduced that the ratio of the pitch diameter D 91 of the main screw 91 to the pitch diameter D 93 of the roller 93 is equal to the ratio of the number of helixes T 91 of the main screw 91 to the number of helixes T 93 of the roller 93, and the number of helixes T 92 of the nut 92 is equal to the number of helixes T 91 of the main screw 91 plus the number of helixes T 93 of the two rollers 93, that is, the corresponding formula can be expressed as D 91 / D 93 = T 91 / T 93 , and T 92 = T 91 + 2T 93 .

[0007] However, in the process of rotating a driving member, the main screw 91, the roller 93 and the nut 92 made according to the above design rules are prone to sliding / skidding, and thus cannot effectively generate the expected rotation and output stroke ratio.

[0008] Therefore, the existing planetary roller screw still needs to be improved. Content of the utility model

[0009] To solve the above problems, the utility model aims to provide a planetary roller screw which can greatly improve the lifting motion precision without reducing the bearing pressure.

[0010] A second object of the utility model is to provide a planetary roller screw which can realize stable motion control.

[0011] The directionality or the approximate language thereof described throughout the utility model, for example, "front", "back", "left", "right", "up (top)", "down (bottom)", "inner", "outer", "side", "axial direction" and "radial direction" and the like, mainly refer to the direction of the attached drawings, and the directionality or the approximate language thereof is only used to assist in the description and understanding of the embodiments of the utility model, and is not used to limit the utility model.

[0012] The quantifier "one" or "a" used in the elements and components described throughout the utility model is only for the convenience of use and to provide the general meaning of the scope of the utility model; in the utility model, it should be interpreted as including one or at least one, and the single concept also includes multiple cases, unless it obviously means otherwise.

[0013] The approximate language such as "combine", "combine", "assemble" or "set" described throughout the utility model mainly includes the type of still separable without damaging the components after connection, or the type of making the components inseparable after connection, which can be selected by the person skilled in the art according to the material or assembly requirement of the components to be connected.

[0014] The planetary roller screw of the utility model, comprising: a main screw, having a first outer thread extending along an axial direction on the outer periphery; a nut, having a through hole extending in the axial direction, the nut having an inner thread extending along an axial direction on the inner wall surface of the through hole; all or part of the first outer thread is located in the through hole of the nut; and a planetary set, having a plurality of rollers, each roller extending along an axial direction, and each roller having a second outer thread on the outer periphery; each roller is at least partially located in the through hole of the nut, and each second outer thread is respectively screwed with the first outer thread and the inner thread; the pitch of the first outer thread, the pitch of the inner thread and the pitch of each second outer thread are equal; the helical direction of the first outer thread is opposite to the helical direction of the inner thread, and the helical direction of the inner thread is the same as the helical direction of the second outer thread; one of the main screw or the nut is used as a driving member, the other two of the main screw, the nut and the planetary set which are not used as the driving member are respectively used as passive members, according to a configuration rule, when the driving member is rotated, the driving member generates relative displacement in the axial direction with each passive member, and no relative displacement is generated in the axial direction between the two passive members; the configuration rule is that the ratio of the pitch diameter between the passive members is the same as the ratio of the helix number, the helix number of the nut is not equal to the helix number of the main screw plus the helix number of the two rollers.

[0015] Therefore, the planetary roller screw of the utility model, through the same direction of the screw direction of the nut / the inner thread and the roller / the second outer thread, and the opposite direction of the screw direction of the main screw rod / the first outer thread, and the configuration rule (the ratio of the pitch circle diameter between the passive members and the ratio of the helix number are the same, and the helix number of the nut is not equal to the helix number of the main screw rod plus the helix number of two rollers), when the specific driving member rotates, the relative displacement between the two driven members in the axial direction cannot be generated, and the driven member generates stable and smooth axial displacement to the driving member in the axial direction, and the corresponding displacement amount reduction ratio is improved, so as to realize more precise displacement control. In particular, through the movement relationship between the driving member and the driven member in the planetary roller screw of the utility model, the planetary roller screw of the utility model can replace the oil cylinder, and be applied to various tools, brake devices, robots and various situations requiring precise control of linear motion.

[0016] In the configuration rule, the nut is the driving member, the ratio of the pitch circle diameter of the main screw rod to the pitch circle diameter of the roller is the same as the ratio of the helix number of the main screw rod to the helix number of the roller; when the driving member rotates, the planetary group generates relative displacement to the nut in the axial direction, and the main screw rod and the planetary group do not generate relative displacement in the axial direction. In this configuration, the nut is used as the driving member, the main screw rod or the planetary group is used as the output, the expected precise motion control can be achieved, and the structural strength can be improved.

[0017] In the configuration rule, the nut is the driving member, the ratio of the pitch circle diameter of the main screw rod to the pitch circle diameter of the roller is the same as the ratio of the helix number of the main screw rod to the helix number of the roller; when the driving member rotates, the planetary group generates relative displacement to the nut in the axial direction, and the main screw rod and the planetary group do not generate relative displacement in the axial direction. In this configuration, the nut is used as the driving member, the main screw rod or the planetary group is used as the output, the expected precise motion control can be achieved, and the structural strength can be improved.

[0018] The planetary group further has a ring frame portion, the ring frame portion is arranged between the main screw rod and the nut and has a plurality of accommodation portions, the number of the plurality of accommodation portions is at least equal to the number of the plurality of rollers, and each roller is accommodated in a corresponding one of the plurality of accommodation portions. In this way, through the configuration of the ring frame portion, the rollers of the planetary group can be stably and uniformly distributed on the outer periphery of the main screw rod, so that the rollers can be uniformly stressed when the planetary group rotates, and the smoothness of the planetary roller screw during operation can be improved.

[0019] The ring frame is a ring-shaped body, and the plurality of accommodating portions are a plurality of through holes formed in the radial direction of the ring frame. In the case where each roller accommodates a corresponding one of the plurality of accommodating portions, a gap is formed in the circumferential direction between each roller and the corresponding accommodating portion. In this way, the gap between each roller and the corresponding accommodating portion in the circumferential direction can improve the smoothness of the rotation between each roller and the main screw and the nut.

[0020] Each roller has a protrusion at each end in the axial direction. The planetary set further has a ring frame disposed between the main screw and the nut. The ring frame has two ring-shaped bodies disposed opposite each other in the axial direction, and each ring-shaped body has a plurality of recesses opposite each other in the axial direction. The protrusions of each roller are partially accommodated in corresponding recesses. In this way, the arrangement of the ring frame can stably and uniformly distribute each roller of the planetary set around the outer periphery of the main screw, thereby ensuring that each roller is uniformly stressed when the planetary set rotates, and thereby improving the smoothness of the planetary roller screw when it operates.

[0021] Each protrusion of each roller is provided with a corresponding elastic element, and each elastic element abuts between the ring frame and the roller. In this way, each elastic element maintains a certain tension in the axial direction of each roller, thereby ensuring that each roller does not deviate in the axial direction during operation.

[0022] The flanks of any one of the first external thread of the main screw, the internal thread of the nut, and the second external thread of each roller are arc-shaped. In this way, the contact area between the second external thread of the roller and the first external thread and the internal thread, respectively, can be reduced, thereby reducing the corresponding friction and improving the smoothness of rotation.

[0023] The first external thread of the main screw further has at least one main screw tooth portion, and the second external thread of each roller of the planetary set has at least one roller tooth portion. In the case where the first external thread and the second external thread produce screwing rotation, the at least one main screw tooth portion and the at least one roller tooth portion simultaneously produce meshing rotation. In this way, the planetary set can rotate with each roller rotating in a pure rolling state, thereby eliminating the situation of unexpected friction caused by sliding and improving the smoothness of the overall planetary roller screw when it operates.

[0024] Wherein, the inner thread of the nut has at least one nut tooth portion, the second outer thread of each roller of the planetary set has at least one roller tooth portion; in a case of screwing rotation between the inner thread and the second outer thread, the at least one nut tooth portion and the at least one roller tooth portion simultaneously generate meshing rotation. Thus, it can be ensured that the planetary set is in rotation, each roller is in the state of pure rolling, and the situation of unexpected friction caused by sliding is excluded, thereby improving the smoothness of the overall planetary roller screw during operation. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 A sectional view of a conventional planetary roller screw;

[0026] Figure 2 A perspective exploded view of a first embodiment of the planetary roller screw of the present application;

[0027] Figure 3 A combined sectional view as shown in Figure 2

[0028] Figure 4 A partial structure enlarged view of the A area as shown in Figure 3

[0029] Figure 5 A schematic diagram of the movement relationship of the planetary roller screw of the present application with the nut as the driving member;

[0030] Figure 6 A schematic diagram of the movement relationship of the planetary roller screw of the present application with the main screw as the driving member;

[0031] Figure 7 A schematic diagram of the main screw and the roller having thread tooth portions that can mesh with each other;

[0032] Figure 8 A schematic diagram of the main screw and the roller having thread tooth portions that can mesh with each other and spur gears;

[0033] Figure 9 A schematic diagram of the nut and the roller having thread tooth portions that can mesh with each other;

[0034] Figure 10 A schematic diagram of the nut and the roller having thread tooth portions that can mesh with each other and spur gears;

[0035] Figure 11 A schematic diagram of another preferred configuration of the planetary set of the planetary roller screw of the present application;

[0036] Figure 12 A schematic diagram of the configuration of elastic elements on each protruding portion of each roller as shown in Figure 11

[0037] ​​​Reference numerals:

[0038] (the utility model)

[0039] 1: main screw

[0040] 1G: main screw tooth part

[0041] 11: first external thread

[0042] 11a: thread part top end

[0043] 11b: thread part bottom end

[0044] 11F: flank

[0045] 12: connecting part

[0046] 2: nut

[0047] 2a: nut top end

[0048] 2b: nut bottom end

[0049] 2G: nut tooth part

[0050] 20: through hole

[0051] 21: internal thread

[0052] 21F: flank

[0053] 3: planetary gear set

[0054] 31: roller

[0055] 31a: roller top end

[0056] 31b: roller bottom end

[0057] 31G: roller tooth part

[0058] 311: second external thread

[0059] 311F: flank

[0060] 312: protrusion

[0061] 32: ring frame part

[0062] 320: accommodating part

[0063] 321: ring body

[0064] 321C: recess

[0065] C: center axis

[0066] E: elastic element

[0067] G: gap

[0068] H: height

[0069] L: length

[0070] P1, P2, P3: pitch

[0071] (Conventional art)

[0072] 9: planetary roller screw

[0073] 91: main screw

[0074] 911: first external thread

[0075] 92: nut

[0076] 921: internal thread

[0077] 93: roller

[0078] 931: second external thread DETAILED DESCRIPTION

[0079] To make the above and other objects, features and advantages of the present application more comprehensible, preferred embodiments will be described in detail as follows, together with the accompanying drawings. In addition, the same reference numerals are used to denote the same elements throughout the drawings.

[0080] Please refer to Figure 2 , Figure 3 , which is a first embodiment of the planetary roller screw of the present application, comprising a main screw 1, a nut 2 and a planetary set 3. The planetary set 3 is located in the nut 2 and surrounds the main screw 1. Through the above configuration, the planetary roller screw can further have a specific movement mode according to a configuration rule proposed by the present application. In particular, based on the configuration rule, the planetary roller screw can have a first configuration or a second configuration, each having a different movement mode. The configuration rule will be described in detail as follows.

[0081] The outer periphery of the main screw 1 has a first external thread 11 extending in the axial direction. The helical direction of the first external thread 11 can be one of right-handed and left-handed. Alternatively, the outer periphery of the main screw 1 further has a connecting portion 12. Preferably, the first external thread 11 can be arranged near one end of the main screw 1, and the connecting portion 12 can be arranged near the other end of the main screw 1. In addition, in order to clearly illustrate the direction configuration in the present application, the main screw 1 is defined as having a center axis C, and the direction extending from the center axis C is defined as the "axial direction" described throughout the present application.

[0082] The nut 2 has a through hole 20 extending in the axial direction, and the inner wall surface of the through hole 20 has an internal thread 21 extending in the axial direction. The helical direction of the internal thread 21 can be one of right-handed and left-handed. In particular, the helical direction of the internal thread 21 is opposite to the helical direction of the first external thread 11. The main screw rod 1 is at least partially located in the through hole 20 of the nut 2. In particular, all or part of the first external thread 11 of the main screw rod 1 is located in the through hole 20 of the nut 2. In other words, all or part of the first external thread 11 is in registration with the internal thread 21 in the radial direction.

[0083] The planetary set 3 has a plurality of rollers 31, and preferably also has a ring frame portion 32. Each roller 31 extends in the axial direction, and the outer periphery of each roller 31 has a second external thread 311. The helical direction of the second external thread 311 can be one of right-handed and left-handed. In particular, the helical direction of the second external thread 311 is the same as the helical direction of the internal thread 21 of the nut 2, i.e., the helical direction of the second external thread 311 is opposite to the helical direction of the first external thread 11 of the main screw rod 1. Each roller 31 is at least partially located in the through hole 20 of the nut 2, and the second external thread 311 of each roller 31 is screwed with the first external thread 11 and the internal thread 21, respectively. Preferably, the plurality of rollers 31 are uniformly distributed around the outer periphery of the main screw rod 1. For example, when the number of the plurality of rollers 31 is N, each roller 31 is arranged around the outer periphery of the main screw rod 1 at an interval angle (360 degrees divided by N). N is a positive integer greater than 1, and preferably is a number that is divisible by 360 degrees.

[0084] Preferably, the planetary set 3 also has a corresponding ring frame portion 32, which is arranged between the main screw rod 1 and the nut 2, and has a plurality of accommodation portions 320. The number of the plurality of accommodation portions 320 is at least equal to the number of the plurality of rollers 31, so that each roller 31 can be accommodated in a corresponding accommodation portion 320. In detail, the number of the plurality of accommodation portions 320 is M, and each accommodation portion 320 is formed in the ring frame portion 32 at an interval angle (360 degrees divided by M). M is a positive integer not less than N, and preferably is a number that is divisible by 360 degrees. In this way, through the arrangement of the ring frame portion 32 and the plurality of accommodation portions 320, the plurality of rollers 31 of the planetary set 3 can be stably and uniformly distributed around the outer periphery of the main screw rod 1.

[0085] In the utility model Figure 2In the illustrated embodiment, the ring frame 32 is annular in shape and extends in the axial direction with a central through hole. The plurality of accommodating portions 320 are formed in the radial direction of the ring frame 32, and each of the accommodating portions 320 has a corresponding profile of each of the rollers 31. When each of the rollers 31 is accommodated in a corresponding one of the accommodating portions 320, a circumferential gap is formed between each of the rollers 31 and the corresponding accommodating portion 320 to facilitate rotation of each of the rollers 31 relative to the main screw 1 / first external thread 11 and the nut 2 / inner thread 21. In this way, the plurality of rollers 31 can be easily installed between the main screw 1 and the nut 2, and the position of each of the rollers 31 between the main screw 1 and the nut 2 can be stably set without being easily deviated.

[0086] Optionally, each of the rollers 31 can have a protrusion 312 extending outwardly in the axial direction (particularly along the central axis of the roller 31) from a corresponding one of the rollers 31. The diameter of the protrusion 312 is not greater than the diameter of the roller 31, and is preferably less than the diameter of the roller 31. When each of the rollers 31 is set in the corresponding accommodating portion 320, and when each of the rollers 31 contacts the ring frame 32 in the axial direction, each of the rollers 31 contacts the ring frame 32 (at the edge position of the corresponding accommodating portion 320) via the protrusion 312 to reduce the friction when each of the rollers 31 rotates in the accommodating portion 320.

[0087] In particular, as shown in Figure 4 the pitch P1 of the first external thread 11, the pitch P2 of the inner thread 21, and the pitch P3 of the second external thread 311 are equal.

[0088] Preferably, the flanks 311F of the second external thread 311 are arc-shaped to reduce the contact area between the second external thread 311 and the first external thread 11 and the inner thread 21, respectively, and to reduce the friction between the second external thread 311 and the first external thread 11 and the inner thread 21, respectively, thereby reducing noise generation and improving rotation smoothness. It should be noted that in other embodiments, any one of the flanks 11F of the first external thread 11, the flanks 21F of the inner thread 21, and the flanks 311F of the second external thread 311 can be arc-shaped, and the present application is not limited in this regard.

[0089] In particular, it should be noted that, as shown in Figures 2 to 4As shown, the height of each roller 31 in the axial direction between the main screw 1 and the nut 2 varies according to the lead angle of the main screw 1 and the nut 2 and the position of each roller 31 in the circumferential direction of the main screw 1 and the nut 2 (having a difference in relative angle). In an actual example, each accommodating portion 320 on the ring frame portion 32 can have a through-hole height H in the axial direction greater than the length L of each roller 31 to have the gap G (as shown in Figure 5 , Figure 6 shown) and the through-hole height H is greater than the length L of each roller 31 by a length of not less than 0.5 pitch P3, preferably not less than 1 pitch P3. Alternatively, in another example (not shown), to facilitate the easy arrangement of each roller 31 between the main screw 1 and the nut 2, the arrangement of the height position of each accommodating portion 320 on the ring frame portion 32 can have a difference according to actual needs. Alternatively, in yet another example (not shown), without changing the arrangement of the height position of each accommodating portion 320 in the axial direction, by making the protruding portions 312 at both ends of each roller 31 have a length in the axial direction, when each roller 31 is arranged in the corresponding accommodating portion 320, it can have a corresponding height in the axial direction suitable for arrangement on the main screw 1 and / or the nut 2.

[0090] Based on the above Figures 2 to 4 arrangement, the utility model proposes an arrangement rule, under the condition that the helical direction of the first external thread 11 of the main screw 1 is opposite to the helical direction of the internal thread 21 of the nut 2 and the helical direction of the internal thread 21 of the nut 2 is the same as the helical direction of the second external thread 311 of each roller 31, one of the main screw 1 or the nut 2 is taken as a driving member, the other two of the main screw 1, the nut 2 and the planetary set 3 that are not the driving member are taken as driven members respectively; the arrangement rule is that the ratio of the pitch circle diameters of the driven members is the same as the ratio of the helix numbers, the helix number of the nut 2 is not equal to the helix number of the main screw 1 plus the helix number of two rollers 31. Preferably, the helix number of the nut 2 is equal to: the helix number of the main screw 1 plus the helix number of two rollers 31, then plus 1 or minus 1; or the helix number of the main screw 1 is equal to: the helix number of the nut 2 minus the helix number of two rollers 31, then plus 1 or minus 1. In this way, according to the above arrangement rule, when the driving member is rotated, the driving member produces relative displacement in the axial direction with respect to each driven member, and no relative displacement in the axial direction between the two driven members.

[0091] In detail, Figure 5A first configuration example according to the above configuration rule is shown, in which the nut 2 is the driving member, the ratio of the pitch diameter of the main screw 1 to the pitch diameter of the roller 31 is the same as the ratio of the number of helical lines of the main screw 1 to the number of helical lines of the roller 31, and the number of helical lines of the nut 2 is not equal to the number of helical lines of the main screw 1 plus the number of helical lines of the two rollers 31 (or the number of helical lines of the main screw 1 is not equal to the number of helical lines of the nut 2 minus the number of helical lines of the two rollers 31), so that the ratio of the pitch diameter of the nut 2 to the pitch diameter of the roller 31 is different from the ratio of the number of helical lines of the nut 2 to the number of helical lines of the roller 31. In order to clearly illustrate the configuration rule, T1 and D1 represent the number of helical lines and the pitch diameter of the main screw 1, respectively, T2 and D2 represent the number of helical lines and the pitch diameter of the nut 2, respectively, and T3 and D3 represent the number of helical lines and the pitch diameter of the roller 31, respectively. The first configuration of the configuration rule can be represented as D1 / D3 = T1 / T3 and T2 ≠ T1+2T3 (T1 ≠ T2-2T3), so that D2 / D3 ≠ T2 / T3. Preferably, the number of helical lines of the nut 2 is equal to the number of helical lines of the main screw 1 plus the number of helical lines of the two rollers 31 plus or minus 1; that is, it can be represented as T2 = T1+2T3±1. Preferably, the number of helical lines of the main screw 1 is equal to the pitch diameter of the main screw 1 divided by the pitch diameter of the roller 3; that is, it can be represented as T1 = D1 / D3.

[0092] More specifically, in a specific example of the first configuration, the pitches of the main screw 1, the nut 2 and the roller 31 are all 1.5 mm, the pitch diameter of the main screw 1 is 18 mm and the number of helical lines is 3, the pitch diameter of the roller 31 is 6 mm and the number of helical lines is 1, and the pitch diameter of the nut 2 is 30 mm and the number of helical lines is 6; when the nut 2 rotates one revolution, the main screw 1 produces a relative displacement of about 0.8 mm with respect to the nut 2. In other words, in this case, the lead of one revolution of the nut 2 is its pitch 1.5 mm multiplied by the number of helical lines 6, which equals 9 mm, divided by the displacement amount 0.8 mm of the main screw 1 or the planetary set 3 as output, so that the corresponding displacement amount reduction ratio is about 11.25 times.

[0093] In detail, Figure 6A second configuration example according to the above configuration rule is shown, in which the main screw 1 is the driving element, the ratio of the pitch diameter of the nut 2 to the pitch diameter of the roller 31 is equal to the ratio of the number of helical lines of the nut 2 to the number of helical lines of the roller 31, and the number of helical lines of the nut 2 is not equal to the number of helical lines of the main screw 1 plus the number of helical lines of the two rollers 31, so that the ratio of the pitch diameter of the main screw 1 to the pitch diameter of the roller 31 is not equal to the ratio of the number of helical lines of the main screw 1 to the number of helical lines of the roller 31. That is, the second configuration in the configuration rule can be represented as D2 / D3 = T2 / T3 and T2 ≠ T1+2T3, so that D1 / D3 ≠ T1 / T3. Preferably, the number of helical lines of the main screw 1 is equal to the number of helical lines of the nut 2 minus the number of helical lines of the two rollers 31 plus or minus 1; that is, it can be represented as T1 = T2-2T3±1.

[0094] More specifically, in a specific example of the second configuration, the pitches of the main screw 1, the nut 2 and the roller 31 are all 4 mm, the pitch diameter of the main screw 1 is 30 mm and the number of helical lines is 4, the pitch diameter of the roller 31 is 10 mm and the number of helical lines is 1, and the pitch diameter of the nut 2 is 50 mm and the number of helical lines is 5; when the main screw 1 rotates one revolution, the nut 2 produces a relative displacement of about 2 mm with respect to the main screw 1. In other words, in this case, the lead of the main screw 1 rotating one revolution is its pitch 4 mm multiplied by the number of helical lines 4, which equals 16 mm, divided by the displacement amount 2 mm of the nut 2 or planetary set 3 as output, so that the corresponding displacement amount reduction ratio is about 8 times.

[0095] Preferably, in another specific example of the second configuration, another condition is met: the number of helical lines of the main screw 1 is equal to the pitch diameter of the main screw 1 divided by the pitch diameter of the roller 3; that is, it can be represented as T1 = D1 / D3. The pitches of the main screw 1, the nut 2 and the roller 31 are all equal, the pitch diameter of the main screw 1 is 20 mm and the number of helical lines is 1, the pitch diameter of the roller 31 is 20 mm and the number of helical lines is 2, and the pitch diameter of the nut 2 is 60 mm and the number of helical lines is 6. In this example, the following formulas are met: D2 / D3 = T2 / T3, T1 = D1 / D3, and T1 = T2-2T3-1 (D1 / D3 ≠ T1 / T3).

[0096] It should be noted that, based on the mechanism of the planetary roller screw of the present application, the helical directions of the inner thread 21 and the second outer thread 311 are the same, and the helical direction of the first outer thread 11 is opposite; in other words, the element configuration from outside to inside can be considered as [nut 2-roller 31-main screw 1], and the corresponding helical direction can be represented as [right-right-left] or [left-left-right].

[0097] It should be noted that, according to this utility model, the planetary roller screw... Figure 5 , Figure 6 According to the configuration rules in this utility model, under the reference that the pitch circle diameters of the main screw 1, the nut 2 and the roller 31 are the same at 3:5:1, in the first configuration with the nut 2 as the driving member, the displacement reduction ratio is approximately 11.25 times, and in the second configuration with the main screw 1 as the driving member, the displacement reduction ratio is approximately 8 times. However, applying similar configuration conditions to existing technologies where all helical directions are in the same direction, with the pitch circle diameter ratio of the main screw 91, nut 92, and roller 93 also being 3:5:1, and the pitch being 4 mm, the main screw 91 having a pitch circle diameter of 30 mm and a helix count of 5, the roller 93 having a pitch circle diameter of 10 mm and a helix count of 1, and the nut 92 having a pitch circle diameter of 50 mm and a helix count of 5; with the main screw 91 as the driving member and rotating one revolution, the relative displacement of the nut 92 relative to the main screw 91 is approximately 20 mm. In other words, in this case, the lead of one revolution of the main screw 91 is its pitch of 4 mm multiplied by the number of helixes of 5, equaling 20 mm. Dividing this by the nut 92 as the output displacement of 20 mm, we obtain a displacement reduction ratio of 1. That is, based on similar configuration conditions, the planetary roller screw proposed in this invention has a better displacement reduction ratio. It should also be noted that the specific proportional relationship of the pitch circle diameters between the components mentioned in this utility model, as well as the specific values ​​of the pitch, pitch circle diameter, and / or number of helixes of each component, are merely examples to more clearly illustrate the content of this utility model and are not intended to limit this application.

[0098] Therefore, based on the helical direction configuration and configuration rules proposed in this invention, using the same or similar pitch configuration as the prior art, this invention can reduce the relative displacement between the main screw 1 and the nut 2, thereby achieving more precise motion control. Furthermore, since the pitch configuration conditions corresponding to the main screw 1, the nut 2, and the roller 31 remain unchanged (not adjusted to be more compact), without additional increase in processing costs, the main screw 1, the nut 2, and the roller 31 can maintain the same load-bearing capacity. In other words, compared to the prior art, to achieve the same displacement accuracy control—that is, when the driven component rotates one revolution and the driven component has the same displacement—the pitch of this invention can be larger, resulting in better load-bearing capacity and saving manufacturing costs.

[0099] Please refer to Figure 7 , Figure 8 As shown, it illustrates another preferred configuration of the main screw 1 and each roller 31 in the planetary roller screw of this invention. Compared to Figures 2 to 4The main screw 1 further has at least one main screw tooth portion 1G; each roller 31 further has at least one roller tooth portion 31G, so that when the first external thread 11 and the second external thread 311 are screwed to rotate, the at least one main screw tooth portion 1G and the at least one roller tooth portion 31G simultaneously rotate in mesh; and through the meshing rotation of the at least one main screw tooth portion 1G and the at least one roller tooth portion 31G, it can be ensured that when the planetary set 3 rotates (each roller 31 revolves around the main screw 1), each roller 31 rotates in a pure rolling state, and the situation of unexpected friction caused by sliding is excluded, thereby improving the smoothness of the overall planetary roller screw during operation.

[0100] In the example shown in Figure 7 , the main screw 1 has a main screw tooth portion 1G arranged in the entire region of the first external thread 11; however, in other examples (not shown), the main screw tooth portion 1G can also be arranged in a single segment or multiple segments in the single or multiple local regions of the first external thread 11 or the main screw 1. Each roller 31 has two roller tooth portions 31G arranged in the local regions of the second external thread 311 near the two ends (i.e. the roller top end 31a and the roller bottom end 31b) in the axial direction; however, in other examples (not shown), the roller tooth portion 31G can also be arranged in a single segment in the entire region of the second external thread 311, or can be arranged in a single segment or multiple segments in the single or multiple local regions of the second external thread 311 or the roller 31. In particular, the main screw tooth portion 1G is a plurality of recessed structures or a plurality of protruding structures formed on the first external thread 11, and the roller tooth portion 31G is a plurality of recessed structures or a plurality of protruding structures formed on the second external thread 311 of each roller 31 for meshing with the main screw tooth portion 1G.

[0101] In the example shown in Figure 8 , the main difference from Figure 7 is that the main screw 1 has another main screw tooth portion 1G arranged outside one of the two ends in the axial direction of the first external thread 11, and the other main screw tooth portion 1G has a spur gear structure; one of the two roller tooth portions 31G is arranged outside one of the two ends in the axial direction of the second external thread 311, and the roller tooth portion 31G has a spur gear structure to mesh with the two main screw tooth portions 1G which are spur gear structures. It should be noted that Figure 8The main screw tooth portion 1G with the spur gear structure shown in the figures and the roller tooth portion 31G, although respectively corresponding to the outer side positions of the threaded portion bottom end 11b and the roller bottom end 31b, can also respectively correspond to the outer side positions of the threaded portion top end 11a and the roller top end 31a in other configuration manners. In other examples (not shown), the main screw tooth portion 1G configured as the spur gear structure can be configured in two sections at the outer side positions of the two ends of the first external thread 11 of the main screw 1, so that the first external thread 11 is arranged between the two sections of the main screw tooth portion 1G; the roller tooth portion 31G configured as the spur gear structure can be configured in two sections at the outer side positions of the two ends of the second external thread 311 of the roller 31, so that the second external thread 311 is arranged between the two sections of the roller tooth portion 31G.

[0102] Similarly Figure 7 , Figure 8 , please refer to Figure 9 , Figure 10 , which shows another preferred configuration of the nut 2 and the rollers 31 in the planetary roller screw of the present application. The nut 2 further has at least one nut tooth portion 2G; each roller 31 further has at least one roller tooth portion 31G, so that when the internal thread 21 and the second external thread 311 are screwed and rotated, the at least one nut tooth portion 2G and the at least one roller tooth portion 31G simultaneously mesh and rotate; and through the meshing and rotation of the at least one nut tooth portion 2G and the at least one roller tooth portion 31G, it can be ensured that when the planetary set 3 rotates (each roller 31 revolves around the main screw 1), each roller 31 rotates in a pure rolling / rotating state, and the situation of unintended friction caused by sliding is excluded, thereby improving the smoothness of the overall planetary roller screw during operation.

[0103] In the example shown in Figure 9 , the nut 2 has a nut tooth portion 2G configured in the entire region of the internal thread 21; however, in other examples (not shown), the nut tooth portion 2G can also be configured in single or multiple sections in single or multiple local regions of the internal thread 21 or the nut 2. Each roller 31 has two roller tooth portions 31G configured in the local regions of the second external thread 311 near the two ends (i.e., the roller top end 31a and the roller bottom end 31b) of the roller 31 in the axial direction; however, in other examples (not shown), the roller tooth portion 31G can also be configured in a single section in the entire region of the second external thread 311, or can be configured in single or multiple sections in single or multiple local regions of the second external thread 311 or the roller 31.

[0104] In the example shown in Figure 10 , which is similar to Figure 9The main difference is that the nut 2 has another nut tooth portion 2G configured at the outer side of one of the axial ends of the internal thread 21, and the other nut tooth portion 2G has a spur gear structure; one of the two roller tooth portions 31G is configured at the outer side of one of the axial ends of the second external thread 311, and the roller tooth portion 31G has a spur gear structure to engage the spur gear structure of the two nut tooth portions 2G. It should be noted that, Figure 10 The nut tooth portion 2G and the roller tooth portion 31G with a spur gear structure shown in the above are respectively configured at the outer side of the nut bottom end 2b and the roller bottom end 31b, but in other configurations, they can also be respectively configured at the outer side of the nut top end 2a and the roller top end 31a. In other examples (not shown), the nut tooth portion 2G configured as a spur gear can be configured in two sections at the outer side of the two ends of the internal thread 21 of the nut 2, so that the internal thread 21 is arranged between the two nut tooth portions 2G; the roller tooth portion 31G configured as a spur gear can be configured in two sections at the outer side of the two ends of the second external thread 311 of the roller 31, so that the second external thread 311 is arranged between the two roller tooth portions 31G.

[0105] It should be noted that according to Figures 7 to 10 shown, in order to make each roller 31 form a pure rolling motion pattern with the main screw rod 1 and the nut 2, the "tooth portion" of the utility model can be configured on the main screw rod 1 and each roller 31, or on the nut 2 and each roller 31, or on the main screw rod 1, the nut 2 and each roller 31; the tooth portion refers to the main screw rod tooth portion 1G, the nut tooth portion 2G and the roller tooth portion 31G. In particular, the position and area / range of the tooth portion configured on the main screw rod 1, the nut 2 and each roller 31 can be set according to the movement range between the main screw rod 1, the nut 2 and each roller 31. In particular, when forming corresponding tooth portion features, the corresponding pitch circle diameters of the first external thread 11, the internal thread 21 and the second external thread 311 should be considered, and preferably the smallest of these pitch circle diameters should be able to divide the others.

[0106] It should also be noted that the tooth portions listed in the above Figure 8 , Figure 10 are achieved by using the structure of a spur gear for parallel axial engagement and rotation, but the utility model is not limited to a spur gear, and includes other structures that can achieve parallel axial engagement and rotation.

[0107] In addition, please refer to Figure 11, showing another preferred configuration of the planetary set 3 in the planetary roller screw of the present application. The ring frame portion 32 of the planetary set 3 has two ring bodies 321 oppositely arranged in the axial direction, and each of the ring bodies 321 has a plurality of recesses 321C oppositely arranged in the axial direction, for the convex portion 312 of each roller 31 to be partially sleeved in the corresponding recess 321C; in particular, and each roller 31 can be in the configuration as shown in Figure 2 、 Figures 7 to 10 . It should be noted that although the recesses 321C shown in the present application Figure 12 are perforated, the configuration of the recesses 321C is not limited thereto; for example, the recesses 321C can be formed as recessed and non-perforated structures.

[0108] Optionally, as shown in Figure 12 , a corresponding elastic element E is arranged on the convex portion 312 of the roller 31, and each elastic element E abuts between the ring frame portion 32 and the roller 31; in this way, each elastic element E will keep each roller 31 under a certain tension in the axial direction, and can ensure that each roller 31 does not deviate in the axial direction during operation. Preferably, the elastic element E can be in the configuration of a coil spring.

[0109] According to the configuration and motion mechanism of the planetary roller screw of the present application described above, one of the main screw 1, the nut 2 and the planetary set 3 is the driving member, and the other two of the main screw 1, the nut 2 and the planetary set 3 are the driven members; when the driving member is rotated, the direction of the linear movement of the nut 2 by the planetary set 3 is opposite to the direction of the linear movement of the planetary set 3 by the main screw 1. In addition, in order to achieve the motion relationship and precision requirements between the main screw 1, the nut 2 and the roller 31, the pitch diameter, the number of helical lines and the pitch of the main screw 1, the nut 2 and the roller 31 can be adjusted respectively.

[0110] In summary, the planetary roller screw of the utility model, through the nut / the inner thread and the roller / the second outer thread of the same direction of the spiral direction, and the main screw / the first outer thread of the opposite spiral direction, and the configuration rule (the ratio of the pitch circle diameter between the passive element and the spiral line number is the same, the spiral line number of the nut is not equal to the spiral line number of the main screw plus the spiral line number of two rollers) is matched, when the specific driving part rotates, the relative displacement between the two driven parts in the axial direction can be avoided, and the driven part generates stable and smooth axial displacement to the driving part in the axial direction, and the corresponding displacement amount reduction ratio is improved, so as to realize more precise displacement control. In particular, through the movement relationship between the driving part and the driven part in the planetary roller screw of the utility model, the planetary roller screw of the utility model can replace the oil cylinder, and be applied to various tools, brake devices, robots and various situations requiring precise control of linear motion.

[0111] It should be particularly noted that the planetary roller screw of the utility model according to the above configuration rule, in particular based on the configuration of the specific relationship between the pitch circle diameter and the spiral line number of the main screw, the nut and the roller, can achieve smooth operation without configuring the main screw tooth part, the nut tooth part and the roller tooth part, that is, without any of the main screw tooth part, the nut tooth part and the roller tooth part, the effect of smooth operation can still be achieved.

[0112] Although the utility model has been disclosed by the above preferred embodiment, it is not intended to limit the utility model, and any person skilled in the art can make various changes and modifications to the above embodiments without departing from the spirit and scope of the utility model, and the changes and modifications still belong to the technical scope protected by the utility model, therefore the protection scope of the utility model includes the text recorded in the appended claims and all changes within the equivalent scope. In addition, when the above several embodiments can be combined, the utility model includes any combined embodiment.

Claims

1. A planetary roller screw characterized by, The invention relates to a planetary roller screw, comprising: a main screw having a first external thread extending in an axial direction on an outer periphery thereof; a nut having a through hole extending in an axial direction, the nut having an internal thread extending in an axial direction on an inner wall surface of the through hole, all or part of the first external thread of the main screw being located in the through hole of the nut; and a planetary set having a plurality of rollers each extending in an axial direction and each having a second external thread on an outer periphery thereof, each roller being at least partially located in the through hole of the nut, and the second external thread of each roller being threadedly engaged with the first external thread and the internal thread, respectively; a pitch of the first external thread, a pitch of the internal thread, and a pitch of the second external thread being equal, a helical direction of the first external thread being opposite to a helical direction of the internal thread, the helical direction of the internal thread being the same as a helical direction of the second external thread, one of the main screw or the nut being defined as a driving member, and the other two of the main screw, the nut, and the planetary set being defined as driven members, the planetary roller screw being configured such that, when the driving member is rotated, the driving member causes relative displacement between each driven member in an axial direction, and no relative displacement between the two driven members in the axial direction, the configuration being such that a ratio of a pitch diameter between the driven members is the same as a ratio of a number of helical threads, a number of helical threads of the nut not being equal to a number of helical threads of the main screw plus a number of helical threads of the rollers.

2. The planetary roller screw of claim 1, wherein, In the configuration, with the nut being the driving member, a ratio of a pitch diameter of the main screw to a pitch diameter of the rollers is the same as a ratio of a number of helical threads of the main screw to a number of helical threads of the rollers, and when the driving member is rotated, the planetary set causes relative displacement between the nut in the axial direction, and no relative displacement between the main screw and the planetary set in the axial direction.

3. The planetary roller screw of claim 1, wherein, In the configuration, a ratio of a pitch diameter of the nut to a pitch diameter of the rollers is the same as a ratio of a number of helical threads of the nut to a number of helical threads of the rollers, and when the driving member is rotated, the planetary set causes relative displacement between the main screw in the axial direction, and no relative displacement between the nut and the planetary set in the axial direction.

4. The planetary roller screw of any one of claims 1 to 3, wherein, The planetary set further has a ring frame arranged between the main screw and the nut, the ring frame having a plurality of accommodating portions, a number of the accommodating portions being at least equal to a number of the rollers, each roller being accommodated in a corresponding one of the accommodating portions.

5. The planetary roller screw of claim 4, wherein, The ring frame is an annular body, the plurality of accommodating portions being formed as a plurality of through holes in a radial direction of the ring frame, respectively, and each roller has a gap in a circumferential direction between the corresponding accommodating portion and the roller.

6. The planetary roller screw of any one of claims 1 to 3, wherein, Each roller has a protrusion on each of two ends thereof in the axial direction, and the planetary set further has a ring frame arranged between the main screw and the nut, the ring frame having two rings arranged opposite to each other in the axial direction, the two rings each having a plurality of recesses arranged opposite to each other in the axial direction, each protrusion of each roller being partially accommodated in a corresponding recess.

7. The planetary roller screw of claim 6, wherein, Each protrusion of each roller is provided with a corresponding elastic element, and each elastic element abuts between the ring frame and the corresponding roller.

8. The planetary roller screw of any one of claims 1 to 3, wherein, Flanks of any one of the first external thread of the main screw, the internal thread of the nut, and the second external thread of each roller are arcuate.

9. The planetary roller screw of any one of claims 1 to 3, wherein, The first external thread of the main screw further has at least one main screw tooth portion, and the second external thread of each roller of the planetary set has at least one roller tooth portion; in a case where screwing rotation occurs between the first external thread and the second external thread, meshing rotation occurs between the at least one main screw tooth portion and the at least one roller tooth portion.

10. The planetary roller screw of any one of claims 1 to 3, wherein, The internal thread of the nut has at least one nut tooth portion, and the second external thread of each roller of the planetary set has at least one roller tooth portion; in a case where screwing rotation occurs between the internal thread and the second external thread, meshing rotation occurs between the at least one nut tooth portion and the at least one roller tooth portion.

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