JP4634116B2 - Roller screw - Google Patents

Description

  The present invention relates to a roller screw in which a roller is interposed between a screw shaft and a nut so as to allow rolling motion.

  A ball screw with a ball that allows rolling motion between the screw shaft and the nut can reduce the coefficient of friction when rotating the screw shaft relative to the nut compared to a screw that makes sliding contact. It has been put to practical use in robot positioning mechanisms, feed mechanisms, automobile steering gears, and the like.

  In recent years, in order to increase the allowable load, a roller screw using a roller instead of a ball as a rolling element has been devised, for example, as in Patent Document 1. In this roller screw, a roller rolling groove is formed on the outer peripheral surface of the screw shaft, and a spiral load roller rolling groove facing the roller rolling groove of the screw shaft is also formed on the inner peripheral surface of the nut. A plurality of rollers are arranged and accommodated as rolling elements in the loaded roller rolling path between the roller rolling groove of the screw shaft and the roller rolling groove of the nut. A circulating member in which a no-load roller return passage is formed in the nut to connect one end and the other end of the load rolling is provided, and the roller rolling the loaded roller rolling path is circulated by the circulating member.

  In the loaded roller rolling path, the roller rolls while receiving a load, so that the distance between a pair of opposing wall surfaces on which the side surfaces of the roller roll is slightly narrower than the diameter of the roller. On the other hand, in the no-load roller return path, the roller is pushed and moved by the succeeding roller, so that a gap is made between the no-load roller return path and the roller. Therefore, the roller moves with play.

  The ball can roll in either direction, but the roller is limited in its rolling direction. When the roller moves from the no-load roller return path to the loaded roller rolling path, the roller may meander and clog due to play of the roller in the no-load roller return path.

  Although a ball screw using a ball as a rolling element has been commercialized, a roller screw using a roller as the rolling element has been devised, for example, as in Patent Document 1, but has not yet been commercialized. It is thought that one of the causes is that it is difficult to circulate the rollers.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a roller screw that prevents a roller from meandering and clogging when moving from a no-load roller return path to a loaded roller rolling path.
JP-A-11-210858

  The present invention will be described below. In addition, in order to make an understanding of this invention easy, the reference number of an accompanying drawing is attached in parenthesis writing, However, This invention is not limited to the form of illustration.

In order to solve the above-mentioned problem, the invention of claim 1 is characterized in that the roller rolling groove (5a) having a spiral shape on the outer peripheral surface is provided.
And a nut (6) in which a spiral roller rolling groove (6a) facing the roller rolling groove (5a) of the screw shaft (5) is formed on the inner peripheral surface. ) And the screw shaft (5)
A plurality of side face rollers (7) arranged in a loaded roller rolling path (9) between the roller rolling groove (5a) of the roller and the roller rolling groove (6a) of the nut (6); The nut (6
) And a circulating member (12, 13) in which a no-load roller return passage (10) connecting one end and the other end of the load roller rolling path (9) is formed.
The no-load roller return passage (1 of the circulating member connected to the load roller rolling path (9)
0) The inner peripheral surface is formed in a quadrangular cross section perpendicular to the traveling direction of the roller (7), and the inner peripheral surface of the unloaded roller return passage (10) of the circulation member is a pair of wall surfaces facing each other. Between (3
6a-36c) and a distance between another pair of wall surfaces (36b-36d) crossing the pair of wall surfaces and facing each other, a taper portion where the width gradually decreases toward the load roller rolling path ( have a 36 a to 36 d), the inner peripheral surface of the unloaded roller return path (10) of the circulation member has a tapered portion and (36 a to 36 d), a gap between the roller (7), A large-diameter portion (35a-35d) connected to the tapered portion (36a-36d), a roller (7) provided on the tip side of the unloaded roller return passage (10) with respect to the tapered portion (36a-36d) The roller screw is characterized by having a small diameter portion (37a to 37d) smaller than the large diameter portion (35a to 35d) .

According to a second aspect of the present invention, in the roller screw according to the first aspect , the small-diameter portion (37a to 37d) of the unloaded roller return passage (10) is the screw as viewed from the axial direction of the screw shaft (5). It is characterized by entering inside the thread of the shaft (5).

The invention according to claim 3 is the roller screw according to claim 1 or 2 , wherein the large diameter portion (35a to 35d), the taper portion (36a to 36d), and the small diameter portion of the circulation member (12, 13). The portion where (37a to 37d) is formed is divided into two at the position of the diagonal line of the quadrangle in section.

According to a fourth aspect of the present invention, in the roller screw according to any one of the first to third aspects, the roller rolling groove (5a) of the screw shaft (5) is formed in a V-shaped cross section, and the nut (6 The roller rolling groove (6a) is also formed in a V-shaped cross section, and the loaded roller rolling path (9) has a roller (7) adjacent to the roller (7) when viewed from the traveling direction of the roller (7). A plurality of rollers (7) are cross-arranged so that the axes are orthogonal to each other.

  According to the first aspect of the present invention, by providing the tapered portion in the unloaded roller return passage, the rollers can be guided to the loaded roller rolling path after the rollers are aligned at the tapered portion. Therefore, the roller can be moved from the no-load roller return path to the loaded roller rolling path without meandering.

  According to the second aspect of the present invention, it is possible to align the rollers having a quadrangular side shape (the positions of the rollers in the axial direction and the direction perpendicular to the axial direction can be made constant).

  According to the third aspect of the present invention, the roller can be moved from the small diameter portion having a shape close to the cross-sectional shape of the load roller rolling path to the load roller rolling path without playing.

  According to invention of Claim 4, the area where the circumference | surroundings of a roller are not enclosed by the small diameter part can be shortened, and a roller can be guide | induced to a load roller rolling path immediately after leaving a small diameter part.

  According to invention of Claim 5, a taper part can be easily formed in a circulation member.

  As in the sixth aspect of the invention, the plurality of rollers may be arranged in a cross arrangement.

  According to the seventh aspect of the present invention, by providing the small-diameter portion with a small gap between the rollers in the no-load roller return path, the rollers can be guided to the loaded roller rolling path after the rollers are aligned at the small-diameter portion. it can. Therefore, the roller can be moved from the no-load roller return path to the loaded roller rolling path without meandering.

  FIG. 1 is a perspective view of a roller screw according to an embodiment of the present invention. The roller screw includes a screw shaft 5 having a spiral roller rolling groove 5a formed on the outer peripheral surface, and a nut 6 having a spiral roller rolling groove 6a facing the roller rolling groove 5a on the inner peripheral surface. With. In the loaded roller rolling path between the roller rolling groove 5 a of the screw shaft 5 and the roller rolling groove 6 a of the nut 6, a plurality of rollers 7 are cross-arranged so that the axes of the adjacent rollers 7 are orthogonal to each other. . A retainer 9 that prevents contact between the rollers 7 is interposed between the rollers 7.

  When the nut 6 is rotated relative to the screw shaft 5, the plurality of rollers 7 move while rolling on the loaded roller rolling path 9 between the roller rolling groove 5a and the roller rolling groove 6a. The roller 7 that has rolled to one end of the loaded roller rolling path 9 passes through the no-load roller return path 10 and is then returned to the other end of the loaded roller rolling path 9 several turns before.

  FIG. 2 is a perspective view of the circulation members 12 and 13 in which the no-load roller return passage 10 is formed. The no-load roller return passage 10 is provided at both ends of the linear passage 11 extending in parallel with the axis of the nut 6 and the arc-shaped direction change passage 16 connecting the linear passage 11 and the load roller rolling passage 9. Consists of.

  A through hole extending in parallel with the axis of the screw shaft 5 is formed in the nut 6, and the pipe 12 is inserted into the through hole. A straight passage 11 having a straight track and a quadrangular cross section is formed in the pipe 12. As will be described in detail later, the linear passage 11 is twisted so that the posture of the roller 7 rotates as the roller 7 moves through the linear passage 11.

  Direction change path constituting members 13 are attached to both end faces of the nut 6 in the axial direction. The direction change path constituting member 13 is formed with a direction change path 16 having an arcuate track and having a square cross section. The direction change path constituting member 13 is divided into an inner peripheral side 32 and an outer peripheral side 31 at a diagonal position of the square cross section of the direction change path 16. Each of the inner peripheral side 32 and the outer peripheral side 31 of these direction change path components 13 has a flange portion. The inner peripheral side 32 and the outer peripheral side 31 of the direction change path constituting member 13 are overlapped and positioned on the end surface of the nut 6, and the flange portion is fixed to the end surface of the nut 6 by fixing means such as a bolt. Since both ends of the pipe 12 are fitted into the direction change path constituting member 13, the pipe 12 is also fixed to the nut 6 by fixing the direction change path constituting member 13 to the nut 6.

  3 shows a side view of the roller screw, and FIG. 4 shows a view taken along line IV-IV in FIG. A labyrinth seal 14 is provided on both end faces in the axial direction of the nut 6 in which the pipe 12 and the direction change path constituting member 13 are incorporated in order to remove foreign substances and prevent the lubricant from leaking from the inside of the nut 6. Is installed. A cap 15 that covers the labyrinth seal 14 is attached to the end surface of the nut 6.

  FIG. 5 shows the screw shaft 5. A spiral roller rolling groove 5 a having a predetermined lead is formed on the outer periphery of the screw shaft 5. In this embodiment, in order to increase the allowable load and shorten the overall length of the nut 6, the number of the roller rolling grooves 5a is set to four. Of course, the number of rolls of the roller rolling groove 5a can be variously set such as one, two, and three.

  FIG. 6 shows a cross-sectional shape perpendicular to the groove of the roller rolling groove 5 a of the screw shaft 5. The roller rolling groove 5a has a V-shaped cross section and an opening angle of 90 degrees. An arc portion 5b for grinding relief is formed at the bottom of the roller rolling groove 5a so as to grind 90 ° intersecting portions.

  FIG. 7 shows a detailed view of the nut 6. 7A shows a front view of the nut 6, FIG. 7B shows a cross-sectional view along the axial direction, and FIG. 7C shows a back view of the nut 6. A spiral roller rolling groove 6 a is formed on the inner peripheral surface of the nut 6 so as to face the roller rolling groove 5 a of the screw shaft 5. The nut 6 is formed with a through hole 17 extending in the axial direction of the nut 6. The through hole 17 has a central portion 17a with a small diameter, and both end portions 17b on both sides of the central portion are formed with a slightly larger diameter than the central portion 17a. The pipe 12 is inserted into the central portion 17a of the through hole 17, and the direction change path constituting member 13 is inserted into both end portions 17b. On the end face of the nut 6, an attachment seat 18 for attaching the direction change path constituting member 13 to the nut 6 is formed. The number of pipes 12 and direction change path constituting members 13 equal to the number of roller rolling grooves 6a (four in this embodiment) is provided, and the rollers 7 that roll in the four roller rolling grooves 6a are circulated.

  FIG. 8 shows a detailed view of the mounting seat 18. The mounting seat 18 is formed with an arc-shaped relief groove 19 having a shape matched to a thin portion (23, see FIG. 15A) of the direction change path constituting member 13 described later. In a normal end cap type ball screw, the end face of the nut is formed flat, and the relief groove 19 is not formed. And the member which comprises a direction change path is attached to a flat part. However, in the case of a roller screw, in order to smoothly circulate the roller 7, the radius of curvature of the direction change path 16 tends to increase. When the radius of curvature of the direction change path 16 is increased, the direction change path constituting member 13 easily interferes with the roller rolling groove 6 a of the nut 6. A curvature of the direction change path 16 is formed by forming a thin portion 23 in the direction change path constituting member 13 and forming a relief groove 19 having a shape matched to the thin portion 23 of the direction change path constituting member 13 on the end surface of the nut 6. Even if the radius is increased, it is possible to prevent the direction change path constituting member 13 from interfering with the roller rolling groove 6a.

  FIG. 9 shows a cross-sectional shape perpendicular to the groove of the roller rolling groove 6 a of the nut 6. The roller rolling groove 6a has a V-shaped cross section and an opening angle of 90 degrees. A circular arc portion 6b for grinding relief is formed at the bottom of the roller rolling groove 6a so as to grind 90 ° intersecting portions.

  FIG. 10 shows a side view of the roller 7. The roller 7 that rolls on the loaded roller rolling path 9 has a cylindrical shape, and its diameter D and height L are substantially equal (exactly, the diameter D of the roller 7 is slightly larger than the height L of the roller). For this reason, the shape of the roller 7 seen from the side surface is close to a square.

  In this embodiment, the sectional shape of the loaded roller rolling path 9 and the unloaded roller return path 10 is formed in a square shape in accordance with the side surface shape of the roller 7. FIG. 11 shows the roller 7 accommodated in the loaded roller rolling path 9. The roller 7 applies a load by compressing the circumferential surface between the wall surface of the roller rolling groove 5a and the wall surface of the roller rolling groove 6a of the nut 6 facing the wall surface. For this reason, only a load in one direction in the axial direction of the screw shaft 5 can be applied. That is, in contrast to one ball carrying a load in one direction of the axial direction of the screw shaft and a direction opposite to the one direction, one roller 7 is unidirectional in the axial direction of the screw shaft 5 (1 ) Or a load in the other direction (2) (in FIG. 11, only a load in one direction (1) is applied). In order to apply loads in one direction (1) and the other direction (2) in the axial direction of the screw shaft 5, the axes 7a and 7b of the adjacent rollers 7 are orthogonal to each other when viewed from the seven traveling directions of the rollers. It is necessary to cross-array to do so. As in this embodiment, the number of rollers 7 that apply a load in one direction (1) may be equal to the number of rollers 7 that apply a load in the other direction (2). When it is desired to change the allowable load, the number of rollers 7 that apply a load in one direction (1) may be different from the number of rollers 7 that apply a load in another direction (2). If the number of rollers 7 is appropriately changed, the allowable load in one direction (1) and the allowable load in the other direction (2) can be arbitrarily changed.

  The diameter D of the roller 7 is a so-called oversize that is slightly larger than the distance between the wall surface of the roller rolling groove 5a of the screw shaft 5 and the wall surface of the roller rolling groove 6a of the nut 6 facing the wall surface. Is used. For this reason, the roller is elastically deformed in the load roller rolling path 9, and a load commensurate with it exists in the nut 6 as a preload. Since the rollers 7 are cross-arranged in the load roller rolling path 9, the load applied to the nut 6 from the rollers 7 acts in a direction in which the adjacent rollers 7 repel each other.

  FIG. 12 shows the center line of the trajectory of the roller 7 that circulates through the spiral loaded roller rolling path 9, the arc-shaped direction changing path 16 as the no-load roller return path 10, and the linear path 11. Fig. (A) shows the trajectory of the roller 7 that moves on the loaded roller rolling path 9 (as viewed from the axial direction of the screw shaft 5), and Fig. (B) shows the trajectory of the roller 7 that circulates the entire endless circuit. (State seen from the side of the screw shaft 5). The track of the roller 7 in the loaded roller rolling path 9 has a circular shape with a radius of RCD / 2 when viewed from the axial direction of the screw shaft 5. The roller trajectory in the straight passage 11 of the no-load roller return passage 10 is a straight line parallel to the axis 5c of the screw shaft 5. The path of the roller 7 on the direction change path 16 is an arc having a radius of curvature R.

  At the joint between the load roller rolling path 9, the direction changing path 16, and the straight path 11, the tangential direction of the track of the roller 7 is continuous. This smoothes these joints. Specifically, in the connecting portion between the load roller rolling path 9 and the direction changing path 16, the tangential direction of the direction changing path 16 is the center line of the load roller rolling path 9 when viewed from the axial direction of the screw shaft 5. And the lead angle of the load roller rolling path 9 in a state viewed from the side of the screw shaft 5. Further, at the connecting portion between the straight passage 11 and the direction change path 16, the tangential direction of the direction change path 16 coincides with the direction in which the center line of the straight passage 11 extends.

  FIG. 13 shows the positional relationship between the direction change path constituting member 13 attached to the end face on one side of the nut 6 and the direction change path constituting member 13 attached to the end face on the other side. As described above, the center line of the straight passage 11 of the no-load roller return passage 10 extends in parallel with the axis 5 c of the screw shaft 5. The center line of the direction change path 16 extends in the tangential direction of the center line of the load roller rolling path 9 when viewed from the axial direction of the screw shaft 5 as shown in FIG. The center line of the direction change path 16 on the near side and the center line of the direction change path 16 on the back side intersect at a predetermined opening angle α. As the radius of curvature of the direction change path 16 increases, the opening angle α tends to increase. In this embodiment, the radius of curvature of the direction change path 16 is set to about 5 times the diameter D of the roller 7, for example, and the opening angle is set to 90 degrees to 100 degrees, for example. As will be described in detail later, the linear passage 11 rotates the posture of the roller 7 moving in the passage by an angle α substantially equal to the opening angle.

  By the way, in the return pipe type roller screw, the roller is scooped up from the intersection P1 of the loaded roller rolling path 9 and the horizontal line 20 in FIG. 13A and returned to the opposite intersection P2. For this reason, the number of windings of the roller is 2.5, 3.5, 4.5, etc., and the fraction is 0.5. On the other hand, in the roller screw of the present embodiment, the opening angle α of the direction change path 16 is 90 to 100 degrees, and is scooped up from the point P3 and returned to the point P4. For this reason, the number of windings of the roller is 2.7, 3.7, 4.7, etc., and the fraction is 0.7. Compared with the return pipe type roller screw, the roller is accommodated in a longer range in the circumferential direction of the load roller rolling path 9, so that the load balance of the roller screw is improved.

  FIG. 14 shows the outer peripheral side 31 of the direction change path component 13. FIG. 14A shows a front view seen from the inner peripheral side 32 of the direction change path constituting member 13, and FIG. 14B shows a side view. The outer peripheral side 31 (hereinafter simply referred to as the outer peripheral side 31) of the direction change path constituent member 13 includes a main body portion 33 in which the direction change path 16 having a radius of curvature R is formed, and a flange portion 34 attached to the end surface of the nut 6. . The direction change path 16 is divided into two at the position of a diagonal line having a square cross section, and the outer peripheral side 31 is formed with the outer peripheral side of the direction change path 16 formed of a groove having a V-shaped cross section. On the wall surfaces 16a and 16b of the V-shaped groove, the large diameter portions 35a and 35b, the tapered portions 36a and 36b connected to the large diameter portions 35a and 35b, and the tip of the direction change path more than the tapered portions 36a and 36b. Small diameter portions 37a and 37b provided on the side are formed.

  The small diameter portion 37b on the screw shaft side is made shorter than the small diameter portion 37a on the nut side in order to avoid interference with the roller rolling groove 5a of the screw shaft 5. Further, the small-diameter portion 37b on the screw shaft side has a radius of curvature RCD / 2, more specifically, on the inner side of the thread of the screw shaft 5 when viewed from the axial direction of the screw shaft 5 shown in FIG. It enters inside the track center line of the roller 7 (center line of the load roller rolling path 9). As a result, the section around the roller 7 not surrounded by the small diameter portions 37a and 37b can be shortened, and the roller 7 can be guided to the load roller rolling path 9 immediately after exiting the small diameter portions 37a and 37b. FIG. 14B shows a state in which the small diameter portions on the inner peripheral side 32 of the direction change path constituting member 13 are combined by a two-dot chain line. The tips of the small diameter portions 37b and 37c are inclined according to the lead angle of the roller rolling groove 5a of the screw shaft 5.

  Further, the outer peripheral side 31 is formed with a protruding portion 27 protruding toward the roller rolling groove 5a of the screw shaft 5, thereby ensuring the strength of the small diameter portion 37b and the tapered portion 36b.

  FIG. 15 is a detailed view of the large diameter portions 35a and 35b, the tapered portions 36a and 36b, and the small diameter portions 37a and 37b. 15A shows a side shape of the outer peripheral side 31 as viewed from the side opposite to FIG. 14B, FIG. 15B shows a detailed view of a portion B of FIG. 15A, and FIG. ) Shows a cross-sectional view taken along the line CC of FIG. 15A, FIG. 15D shows a cross-sectional view taken along the line DD of FIG. 15B, and FIG. 15E shows the cross-sectional view of FIG. EE line sectional drawing is shown. 15 (C) to 15 (E), a state where the inner peripheral side 32 of the direction change path constituting member 13 is combined is indicated by a two-dot chain line.

  As shown in FIG. 15C, in the large diameter portions 35 a and 35 b, the distance L <b> 1 between the opposing wall surfaces of the direction change path 16 having a square cross section is larger than the diameter of the roller 7. Is set to have a gap. This gap is determined to be a size that allows the roller 7 to move smoothly along the direction change path 16 of the arcuate track while being pushed by the subsequent roller 7, for example, 4 to 10% of the diameter of the roller 7.

  As shown in FIG. 15D, at the ends of the tapered portions 36a and 36b on the large-diameter portion side, the distance L2 between the opposing wall surfaces of the direction change path 16 having a quadrangular section is the large-diameter portions 35a and 35b. It is equal to the distance L1. In the tapered portions 36a and 36b, the distance L2 between the pair of wall surfaces facing each other and the distance L2 between the other pair of wall surfaces orthogonal to the wall surfaces and facing each other gradually increase toward the small diameter portions 37a and 37b. Becomes narrower. As a result, in the small diameter portions 37a and 37b shown in FIG. 15 (E), the distance L3 between the opposing wall surfaces of the direction change path 16 having a quadrangular section is smaller than the distance L1 in the large diameter portion. The gap between the roller 16 and the roller 7 is smaller than the large diameter portions 35a and 35b. The clearance between the small-diameter portions 37a and 37b is determined to be, for example, 0.5 to 3% of the diameter of the roller 7 so that the roller 7 can move without play.

  FIG. 16 shows the inner peripheral side 32 of the direction change path component 13. 16A shows a side view, FIG. 16B shows a rear view, and FIG. 16C shows a front view on the inner peripheral side as viewed from the nut side. The inner peripheral side 32 (hereinafter simply referred to as the inner peripheral side 32) of the direction change path constituting member 13 includes a main body portion 38 in which the direction change path 16 having a curvature radius RCD / 2 is formed, and a flange portion 39. The direction change path 16 is divided into two at the position of a diagonal line having a square cross section, and the inner peripheral side 32 is formed with the inner peripheral side of the direction change path 16 formed of a groove having a V-shaped cross section. On the wall surfaces 16c and 16d of the V-shaped groove, the large diameter portions 35c and 35d, the tapered portions 36c and 36d connected to the large diameter portions 35c and 35d, and the direction change path 16 than the tapered portions 36c and 36d. Small diameter portions 37c and 37d provided on the distal end side are formed.

  The small diameter portion 37c on the screw shaft side is shorter than the small diameter portion 37d on the nut side in order to avoid interference with the roller rolling groove 5a of the screw shaft 5. Further, the small diameter portion 37c on the screw shaft side has a radius of curvature RCD / 2, more specifically, on the inner side of the thread of the screw shaft 5 when viewed from the axial direction of the screw shaft 5 shown in FIG. It enters inside the track center line of the roller 7 (center line of the load roller rolling path 9). FIG. 16A shows a state in which the small diameter portions 37b on the outer peripheral side 31 of the direction change path constituting member 13 are combined by a two-dot chain line. The tips of the small diameter portions 37b and 37c are inclined according to the lead angle of the roller rolling groove 5a of the screw shaft 5. As shown in FIG. 16C, the direction change path 16 having a square cross section is formed by combining the outer peripheral sides 31 of the direction change path constituting members 13.

  On the inner peripheral side 32 of the direction change path constituting member 13, a thin portion 23 is formed which protrudes toward the nut side from the end face of the nut 6 and is bent in a curved shape in accordance with the shape of the direction change path 16. The cross-sectional shape of the thin portion 23 is formed in a V shape. This thin portion 23 is fitted into a relief groove 19 (see FIG. 8) formed on the end face of the nut 6.

  FIG. 17 is a detailed view of the large diameter portions 35c and 35d, the tapered portions 36c and 36d, and the small diameter portions 37c and 37d. 17A shows a side shape of the inner peripheral side 32, FIG. 17B shows a cross-sectional view taken along line BB in FIG. 17A, and FIG. 17C shows C in FIG. 17A. FIG. 17D is a detailed view of a portion D in FIG. 17A, FIG. 17E is a cross-sectional view taken along the line EE in FIG. 17D, and FIG. FIG. 17F is a sectional view taken along line FF in FIG. The state which combined the outer peripheral side 31 of the direction change path structural member 13 with FIG. 17 (B), (C), (E), (F) is shown with a dashed-two dotted line.

  As described above, in the large diameter portions 35c and 35d shown in FIGS. 17B and 17C, the distance L1 between the opposing wall surfaces of the direction change path 16 having a square cross section is larger than the diameter of the roller 7. The gap between the roller 7 and the roller 7 is set. At the end on the large diameter side of the tapered portions 36c and 36d shown in FIG. 17E, the distance L2 between the opposing wall surfaces of the direction change path 16 having a square cross section is the distance L1 in the large diameter portions 35c and 35d. equal. In the taper portions 36c and 36d, the distance between the pair of wall surfaces 36a to 36c facing each other and the distance between the other pair of wall surfaces 36b to 36d perpendicular to the wall surface and facing each other face toward the small diameter portions 37c and 37d. The width gradually decreases. As a result, on the small diameter side 37c, 37d shown in FIG. 17F, the distance L3 between the opposing wall surfaces of the direction change path 16 having a quadrangular cross section is smaller than the distance L1 at the large diameter parts 35c, 35d. The gap between the direction change path 16 and the roller 7 is smaller than that of the large diameter portions 35c and 35d. In addition, the inner diameters of the small diameter portions 37a to 37d are thereby substantially equal to the cross-sectional shape of the roller rolling groove 5a of the load roller rolling path 9.

  In addition, the outer peripheral side 31 and the inner peripheral side 32 of the direction change path structural member 13 may be made of metal or resin.

  The small-diameter portions 37a and 37b on the outer peripheral side 31 and the small-diameter portions 37c and 37d on the inner peripheral side of the direction change path constituting member 13 cooperate with each other to move the roller 7 rolling on the spiral load roller rolling path 9 in the tangential direction. Crawling up. Immediately after scooping up the direction change path 16, the direction of the roller 7 is changed, and the roller 7 is moved along the arc-shaped direction change path 16. On the other hand, the direction change path 16 moves the roller 7 entering from the straight path 11 of the no-load return path 10 along the arc-shaped direction change path 16 so that the load roller rolls from the small diameter portions 37a to 37d. Guide to runway 9.

  In the loaded roller rolling path 9, the roller 7 rolls while receiving a load, so that the distance between the pair of opposing wall surfaces of the loaded roller rolling path 9 is slightly narrower than the diameter of the roller 7. On the other hand, in the no-load roller return path 10 including the direction change path 16, the roller 7 is pushed and moved by the succeeding roller 7, so that a gap is provided between the no-load roller return path 10 and the roller 7. Therefore, the roller 7 moves with play. If the roller 7 enters the loaded roller rolling path 9 with the roller 7 tilted due to play in the unloaded roller return passage 10, the roller 7 may be clogged.

  By providing the taper portions 36 a to 36 d on the direction change path 16, after the rollers 7 are aligned by the taper portions 36 a to 36 d, the roller 7 can be guided to the load roller rolling path 9. Therefore, the roller 7 can be moved from the no-load roller return passage 10 to the load roller rolling path 9 without meandering. Further, by providing the small diameter portions 37 a to 37 d having a shape close to the inner diameter of the load roller rolling path 9, the roller 7 can be moved from the small diameter portions 37 a to 37 d to the load roller rolling path 9 without playing.

  On the contrary, when the roller 7 moves from the loaded roller rolling path 9 to the unloaded roller return path 10, the roller 7 passes through the small diameter portions 37a to 37d and the tapered portions 36a to 36d. A large play can be given gradually without giving a big play suddenly, and the roller 7 moves smoothly.

  FIG. 18 shows a cross-sectional view of the pipe 12. While the roller passes through the straight passage 11 of the unloaded roller return passage 10, the straight passage 11 is twisted so that the posture of the roller 7 rotates. The roller 7 rotates around the center line 12 a while moving along the center line 12 a of the straight passage 11. Here, the moving distance of the roller 7 is proportional to the rotation angle of the roller 7. In this example, the roller 7 rotates about 90 degrees + 2β degrees (= a pair of direction change path opening angles α as seen from the axial direction of the screw shaft) from one end to the other end of the no-load roller return passage 10. The pipe 12 is divided into two along the center line. The pipe 12 may be made of metal or resin.

  FIG. 19 shows the rotation of the posture of the roller 7 moving in the straight path 11. It can be seen from FIG. 19 that as the linear path 11 is moved, the position of A1 of the roller 7 moves from the upper left to the lower left, and the posture of the roller 7 rotates about 90 degrees.

  By rotating the posture of the roller 7 in the linear passage 11, the roller 7 is scooped up from the loaded roller rolling path 9, and when the roller 7 is returned to the loaded roller rolling path 9, the posture of the roller 7 having a square side surface is changed. It can be made to correspond to the shape of the load roller rolling path 9 having a square cross section.

Further, by rotating the posture of the roller 7 by an angle substantially equal to the opening angle α of the pair of direction change paths 16, the roller loaded with the load from one direction (1) of the axis of the screw shaft 5 does not reverse. (In a state where the load from the one direction (1) of the axis of the screw shaft 5 can be applied again) returns to the load roller rolling path 9. Further, the retainer 8 interposed between the rollers 7 can be returned without being reversed.
When viewed from the axial direction of the screw shaft 5, the retainer 8 is configured such that the axis of the roller 7 that rolls on the annular load roller rolling path 9 is directed to the center line of the screw shaft 5 (this causes the roller 7 to tilt from a predetermined axis). Phenomenon, so-called skew can be prevented), and some are formed in a sector shape. When the fan-shaped retainer 8 is inverted, the width on the outer peripheral side of the retainer 8 must be wide, but the width on the inner peripheral side is increased. By rotating the posture of the roller 7 by an angle α substantially equal to that of the pair of direction change paths 16, the roller 7 and the retainer 8 can be prevented from being reversed.

  FIG. 20 shows a detailed view of an example of the retainer 8 used in the present embodiment. The retainer 8 holds the posture of the roller 7 so that the axis of the adjacent roller 7 is kept at a right angle. The retainer 8 in FIG. 20 is a flat one that does not change in thickness between the inner peripheral side and the outer peripheral side of the annular load roller rolling path 9, unlike the fan-shaped retainer 8. Of course, a fan-shaped retainer 8 can also be used.

  The present invention is not limited to the above-described embodiment, and can be embodied in other embodiments without changing the gist of the present invention. For example, the circulation member is not limited to the end cap type circulation member as in this embodiment, and various types of circulation members such as a return pipe method can be used. In this embodiment, cylindrical rollers having substantially the same diameter and length are used, and the cross-sectional shape of the unloaded roller return passage is formed in a square shape. However, other cylindrical rollers having different diameters and lengths may be used. The cross-sectional shape of the unloaded roller return path may be formed in a rectangular shape according to the shape of the roller, or a conical roller may be used, and the cross-sectional shape of the unloaded roller return path is changed to a conical roller. A combined trapezoidal shape may be formed.

  Moreover, you may make it a load roller rolling path come immediately after a taper part, without providing a small diameter part in a no-load roller return path. The taper portion may not be formed on all four wall surfaces of the no-load roller return passage, but may be formed only on a pair of opposite wall surfaces of the no-load roller return passage, or one of the pair of opposite wall surfaces. It may be formed only on the wall surface (that is, only one of the four wall surfaces in total). Furthermore, although the roller circulation is somewhat worse, a step may be provided between the large diameter portion and the small diameter portion without providing a taper portion in the no-load return passage.

  Furthermore, the trajectory of the direction change path may not be an arc having a constant curvature, but may be various curves such as a clothoid curve.

The perspective view of the roller screw in one Embodiment of this invention. The disassembled perspective view of the main components of a roller screw. The side view of the roller screw which combined all the parts. FIG. 4 is a view taken along line IV-IV in FIG. 3. The side view which shows a screw shaft. The figure which shows the groove | channel perpendicular | vertical cross-sectional shape of the roller rolling groove | channel of a screw shaft. Detailed view of nut 6 (FIG. (A) shows a front view of the nut, (B) shows a cross-sectional view along the axial direction, and (C) shows a back view). The detailed view of the mounting seat of a direction change path component ((B) is a BB line sectional view of (A)). The figure which shows the groove | channel perpendicular | vertical cross-sectional shape of the roller rolling groove | channel of a nut. The side view of a roller. Sectional drawing which shows the roller in a load roller rolling path. The figure which shows the track | orbit of the roller which circulates through an infinite circuit ((A) shows the state seen from the axial direction of a screw shaft, (B) shows the state seen from the side of a screw shaft). The figure which shows the positional relationship of a pair of direction change path structural member ((A) shows the state seen from the axial direction of a nut, (B) is sectional drawing along the axial line of a nut). The figure which shows the outer peripheral side of a direction change path structural member (FIG. 14 (A) shows the front view seen from the inner peripheral side of the direction change path structural member, FIG.14 (B) shows a side view.). Detailed drawing of a large diameter part, a taper part, and a small diameter part. (FIG. 15 (A) shows a side shape, FIG. 15 (B) shows a detailed view of a portion B in FIG. 15 (A), and FIG. 15 (C) shows a cross-sectional view taken along the line CC in FIG. 15D is a cross-sectional view taken along the line DD in FIG. 15B, and FIG. 15E is a cross-sectional view taken along the line EE in FIG. 15B. The figure which shows the inner peripheral side 32 of a direction change path structural member (FIG. 16 (A) shows a side view, FIG.16 (B) shows a rear view, FIG. (C) is the front of the inner peripheral side seen from the nut side. Shows the figure). Detailed views of the large-diameter portion, the tapered portion, and the small-diameter portion are shown (FIG. 17A shows a side surface shape, FIG. 17B shows a cross-sectional view along line BB in FIG. 17A, and FIG. C) is a cross-sectional view taken along the line CC of FIG. 17A, FIG. 17D is a detailed view of a portion D of FIG. 17A, and FIG. 17E is an E of FIG. -E line sectional drawing is shown, FIG.17 (F) shows the FF sectional view taken on the line of FIG.17 (D)). Sectional drawing of a pipe. The figure which shows rotation of the attitude | position of the roller 7 which moves a linear channel | path. Detailed view of retainer.

Explanation of symbols

5a ... Roller rolling groove 5 ... Screw shaft 6 ... Nut 6a ... Roller rolling groove 7 ... Roller 9 ... Loaded roller rolling path 10 ... Unloaded roller return path 12 ... Pipe (circulation member)
13 ... Direction change path component (circulation member)
16. Direction change path (unloaded roller return path)
31 ... Outer peripheral side 32 of the direction change path constituent member ... Inner peripheral side 35a-35d of the direction change path constituent member ... Large diameter part 36a-36d ... Tapered part 37a-37d ... Small diameter part

Claims (4)

A screw shaft having a spiral roller rolling groove formed on the outer peripheral surface;
A nut in which a spiral roller rolling groove facing the roller rolling groove of the screw shaft is formed on the inner peripheral surface;
A plurality of square-shaped rollers arranged in a loaded roller rolling path between the roller rolling groove of the screw shaft and the roller rolling groove of the nut;
A circulating member attached to the nut and formed with a no-load roller return path connecting one end and the other end of the loaded roller rolling path,
The inner peripheral surface of the unloaded roller return passage of the circulating member connected to the loaded roller rolling path is formed in a quadrangular cross section perpendicular to the roller traveling direction,
The inner peripheral surface of the no-load roller return passage of the circulation member has a distance between a pair of wall surfaces facing each other and a distance between the other pair of wall surfaces intersecting the pair of wall surfaces and facing each other. rolling toward the runway and gradually have a tapered portion in which the width is narrowed,
The inner peripheral surface of the no-load roller return passage of the circulation member is
The tapered portion;
A large-diameter portion having a gap between the rollers and connected to the tapered portion;
Provided on the tip side of the no-load roller return path from the taper portion,
A roller screw having a small-diameter portion that is less than the large-diameter portion. The small diameter portion of the no-load roller return path is:
2. The roller screw according to claim 1 , wherein the roller screw enters an inner side of a screw thread of the screw shaft as viewed from an axial direction of the screw shaft. 3. The roller screw according to claim 1, wherein a portion where the large diameter portion, the taper portion, and the small diameter portion of the circulation member are formed is divided into two at the position of a diagonal line of a square cross section. The roller rolling groove of the screw shaft is formed in a V-shaped cross section,
The roller rolling groove of the nut is also formed in a V-shaped cross section,
The the load roller rolling path, when viewed from the traveling direction of the roller, any one of claims 1, wherein a plurality of rollers such that the axis line of adjacent rollers are perpendicular to each other are cross-arranged 3 Roller screw as described in.

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