Motion guide device

Abstract

To provide a motion guide device which smoothly moves.SOLUTION: In view from a direction perpendicular to a plane including a rolling path and a return path (Fig.8(a)), a first ball passage locus 41 of a first ball passage part is arranged outside a second ball passage locus 42 of a second ball passage part at an end Q1 on the rolling path side of a turn path and at an end Q2 on the return path side, and the first ball passage locus 41 is arranged inside the second ball passage locus 42 at a peak Q3 of the turn path. The peripheral length of the first ball passage locus 41 of the turn path is substantially the same as the peripheral length of the second ball passage locus 42 of the turn path.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to a motion guide device that guides the linear motion of a movable body. [Background technology]

[0002] The motion guide device includes a track member and a carriage that is attached to the track member via a large number of balls so as to be capable of linear motion. The track member is attached to a fixed body such as a base. The carriage is attached to a movable body such as a table. The linear motion of the movable body relative to the fixed body is guided by the motion guide device.

[0003] The track member is formed with a rolling portion along which the balls roll. The carriage is also formed with a rolling portion along which the balls roll. The circulation path includes a rolling path between the rolling portion of the track member and the rolling portion of the carriage, and a turn path and a return path provided in the carriage. When the carriage moves linearly along the track member, the balls roll on the rolling path and circulate in the circulation path. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2003-343556 A Summary of the Invention [Problem to be solved by the invention]

[0005] In order to reduce waving (reducing ball passing vibration) in a motion guide device, two rows of balls may be arranged in a staggered pattern in the first and second ball passing sections of the circulation path. By having the two rows of balls alternately enter and exit the rolling path, it is possible to reduce waving.

[0006] If the two rows of balls are held by a retainer band, the positions of the two rows of balls can be determined. However, if the two rows of balls are not held by a retainer band, the positions of the two rows of balls cannot be determined. This causes the balls in the first ball passing section to overtake the balls in the second ball passing section on the turning path, which makes it difficult to obtain a motion guide device that moves smoothly.

[0007] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a motion guide device that moves smoothly in which two rows of balls are not held by a retainer band. [Means for solving the problem]

[0008] In order to solve the above problems, one aspect of the present invention is a motion guide device that includes a track member having a rolling part, and a carriage having a rolling part opposite to the rolling part, a return path, and a turning path, and in which two rows of balls are arranged in adjacent first and second ball passing sections of a circulation path including the rolling path between the rolling part of the track member and the rolling part of the carriage, the return path, and the turning path, wherein the two rows of balls are not held by a retainer band, and when viewed from a direction perpendicular to a plane including the rolling path and the return path, a first ball passing locus of the first ball passing section is arranged outside a second ball passing locus of the second ball passing section at the end of the turning path on the rolling path side and the end of the turning path on the return path side, and the first ball passing locus is arranged inside the second ball passing locus at the apex of the turning path, and the perimeter of the first ball passing locus of the turning path and the perimeter of the second ball passing locus of the turning path are set to be substantially identical. Effect of the Invention

[0009] According to the present invention, since the first ball passing path and the second ball passing path on the turning path are configured as described above, it is possible to provide a motion guide device with smooth movement. [Brief description of the drawings]

[0010] [Figure 1] 1 is a perspective view (including a partial cross section) of a motion guide device according to a first embodiment of the present invention. [Diagram 2] 3 is a perpendicular cross-sectional view of a track member of the motion guide device of the present embodiment. FIG. [Diagram 3] FIG. 3(a) is a perpendicular cross-sectional view of the rolling path of the motion guide device of this embodiment, FIG. 3(b) is a perpendicular cross-sectional view of the return path, and FIG. 3(c) is a perpendicular cross-sectional view of the turning path. [Figure 4] FIG. 2 is a perspective view of an inner plate of the motion guide device of the present embodiment. [Diagram 5] 2 is a perspective view of an end plate of the motion guide device of the present embodiment. FIG. [Figure 6] FIG. 6(a) is a perspective view showing two rows of balls arranged on a turning path of the motion guide device of this embodiment, and FIG. 6(b) is a diagram showing a first ball passing trajectory and a second ball passing trajectory on the turning path. [Figure 7] FIG. 7(a) is a plan view of a turning road of the motion guide device of this embodiment, FIG. 7(b) is a front view of the turning road, and FIG. 7(c) is a side view of the turning road. [Figure 8] 8(a), (b), and (c) are diagrams showing the first ball passing trajectory and the second ball passing trajectory as viewed from the same direction as FIG. 7(a), (b), and (c). [Figure 9] Figure 9(a) shows a rectangular virtual plate whose short side is set to the distance between the first ball passing trajectory and the second ball passing trajectory on the turning path and whose long side is set to the perimeter of the first ball passing trajectory and the second ball passing trajectory on the turning path, and Figure 9(b) shows the virtual plate curved along the turning path. [Figure 10] FIG. 10(a) is a diagram showing the transmission of force of a ball on a turning road of the motion guide device of this embodiment, and FIG. 10(b) is a diagram showing the transmission of force of a ball on a turning road of a comparative example. [Figure 11] FIG. 6 is a perpendicular sectional view of a track member of a motion guide device according to a second embodiment of the present invention. [Figure 12]FIG. 12(a) is a perpendicular cross-sectional view of the rolling path of a motion guide device of a second embodiment of the present invention, FIG. 12(b) is a perpendicular cross-sectional view of the return path, and FIG. 12(c) is a perpendicular cross-sectional view of the turning path. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, a motion guide device according to an embodiment of the present invention will be described with reference to the accompanying drawings. However, the motion guide device according to the present invention can be embodied in various forms and is not limited to the embodiments described in this specification. The present embodiment is provided with the intention of enabling a person skilled in the art to fully understand the invention by fully disclosing the specification. (First embodiment)

[0012] Figures 1 to 3 show a motion guide device according to a first embodiment of the present invention. Figure 1 shows a perspective view of the motion guide device. Figure 2 shows a perpendicular cross-sectional view of a track member of the motion guide device. Figure 3 shows an enlarged cross-sectional view of the rolling path, return path, and turning path of the motion guide device.

[0013] In the following description, for convenience, the configuration of the motion guide device will be described using the directions when the motion guide device arranged on a horizontal plane is viewed from the relative movement direction of the carriage 2, that is, the up-down, left-right, and front-back directions in Figures 1 and 2. The arrangement of the motion guide device is not limited to this.

[0014] As shown in FIG. 1, the motion guide device includes a track member 1 and a carriage 2. The track member 1 is attached to a base or the like (not shown). The carriage 2 is attached to a table or the like (not shown). The carriage 2 can move linearly along the track member 1. A large number of balls 6 are interposed between the track member 1 and the carriage 2. The carriage 2 is provided with a circulation path 7 for circulating the large number of balls 6. There are, for example, four circulation paths 7 in total, which are provided above and below the left and right sides of the carriage 2. The circulation path 7 includes a rolling path C1 between the rolling part 12 of the track member 1 and the rolling part 13 of the carriage 2, a return path C2 and a turn path C3 provided in the carriage 2. Two rows of balls 6 are arranged in the circulation path 7. The two rows of balls 6 are not held by a retainer band. In the rolling path C1, the two rows of balls 6 roll while receiving a load. On the return path C2 and the turn path C3, the balls 6 in the two rows move while being pushed by the following balls 6.

[0015] The track member 1 is rail-shaped. The track member 1 has, for example, four rolling portions 12 formed thereon. On the left and right sides of the upper part of the track member 1, ridges 11 are formed protruding in the left-right direction. The rolling portions 12 are formed above and below the ridges 11 so as to sandwich the ridges 11. The rolling portions 12 have two rolling grooves 1a in which two rows of balls 6 roll. The rolling grooves 1a are circular arc grooves whose cross section is, for example, a single circular arc. The track member 1 has mounting holes 1b for mounting the track member 1 to a base or the like.

[0016] The carriage 2 includes a carriage body 3, an inner plate 4 attached to both end surfaces of the carriage body 3, and an end plate 5 attached to both end surfaces of the carriage body 3 so as to cover the inner plate 4. A return path C2 is provided in the carriage body 3. A substantially U-shaped return path C3 is formed between the inner plate 4 and the end plate 5.

[0017] As shown in Fig. 2, the carriage body 3 has a central portion 3a facing the upper surface of the track member 1, and left and right sleeve portions 3b facing the side surfaces of the track member 1. The sleeve portions 3b of the carriage body 3 are formed with rolling portions 13 facing the rolling portions 12 of the track member 1. As shown in Fig. 3(a), the rolling portion 13 has two rolling grooves 3c in which two rows of balls 6 roll. The rolling grooves 3c are, for example, circular arc grooves whose cross section is a single arc.

[0018] Between the rolling parts 13 of the carriage body 3 and the rolling parts 12 of the track member 1, a linear rolling path C1 is formed extending in the longitudinal direction of the track member 1. The rolling path C1 has a first ball passing portion 21 and a second ball passing portion 22 adjacent to each other. In the first ball passing portion 21 and the second ball passing portion 22, two rows of balls 6 are arranged in a staggered pattern. When viewed from the traveling direction of the balls 6, adjacent balls 6 partially overlap each other. In the rolling path C1, the balls 6 roll while receiving a load. The symbol θ in FIG. 2 is a contact angle that indicates the direction in which the balls 6 receive a load. The contact angle θ is set to, for example, 30 to 60°.

[0019] As shown in Fig. 2, through holes 14 are formed parallel to the rolling path C1 above and below the left and right sleeves 3b of the carriage body 3. Two half pipes 8, 9 are inserted into the through holes 14. Two raceway surfaces 8a, 9a with arc-shaped cross sections are formed in each half pipe 8, 9. A return path C2 extending in the longitudinal direction of the track member 1 is formed between the raceway surface 8a of the half pipe 8 and the raceway surface 9a of the half pipe 9. The return path C2 is linear and parallel to the rolling path C1.

[0020] The return path C2 is disposed offset from the direction of the contact angle line N1. The upper return path C2 is disposed below the contact angle line N1 of the upper ball 6. The lower return path C2 is disposed above the contact angle line N2 of the lower ball 6. This allows the carriage 2 to be made more compact.

[0021] As shown in FIG. 3(b), the return path C2 has a first ball passing portion 21 and a second ball passing portion 22 adjacent to each other. The right-angled cross section of the return path C2 is gourd-shaped, and the first ball passing portion 21 and the second ball passing portion 22 of the return path C2 are based on two imaginary circles that partially overlap each other. In the first ball passing portion 21 and the second ball passing portion 22, two rows of balls 6 are arranged in a staggered pattern. Adjacent balls 6 partially overlap each other when viewed from the traveling direction of the balls 6. In the return path C2, unlike the rolling path C1, the balls 6 move while being pushed by the following balls 6. A gap is provided between the balls 6 and the first ball passing portion 21, and a gap is provided between the balls 6 and the second ball passing portion 22.

[0022] As shown in FIG. 4, the inner plate 4 has a central portion 4a facing the upper surface of the track member 1, and a pair of left and right sleeve portions 4b facing the side surfaces of the track member 1. An approximately semi-cylindrical R piece portion 31 is formed above and below the left and right sleeve portions 4b of the inner plate 4. Two track surfaces 31a having an arc-shaped cross section are formed on the outer periphery of the R piece portion 31. Reference numeral 31b denotes two rolling grooves connected to two rolling grooves 3c of the carriage body 3, which face two rolling grooves 1a of the track member 1 and function as rolling portions. However, the radius of the arc of the cross section of the rolling groove 31b may be made larger than that of the rolling groove 3c, or a step may be provided between the rolling groove 31b and the rolling groove 3c, so that the load received by the ball 6 rolling in the rolling groove 31b is reduced or eliminated. Reference numeral 31c denotes the end of the track surface 31a on the rolling path C1 side, that is, the end of the turn path C3 on the rolling path C1 side. Reference numeral 31d denotes an end portion of the track surface 31a on the return path C2 side, that is, an end portion of the turning path C3 on the return path C2 side.

[0023] As shown in FIG. 5, the end plate 5 also has a central portion 5a facing the upper surface of the track member 1, and a pair of left and right sleeve portions 5b facing the side surfaces of the track member 1. Recesses 32 into which the R piece portion 31 fits are formed above and below the left and right sleeve portions 5b of the end plate 5. Two track surfaces 32a having an arc-shaped cross section are formed in the recess 32. A substantially U-shaped turn path C3 is formed between the track surface 31a of the R piece portion 31 of the inner plate 4 and the track surface 32a of the recess 32 of the end plate 5. The end plate 5 and the inner plate 4 are attached to the carriage body 3 by screws. Through holes 37 and 38 for screws are formed in the end plate 5 and the inner plate 4.

[0024] FIG. 3(c) shows a right-angled cross section of the turning path C3 at the top of the turning path C3. Reference numeral 4 denotes an inner piece, and reference numeral 5 denotes an end piece. The turning path C3 has a first ball passing portion 21 and a second ball passing portion 22 adjacent to each other. The right-angled cross section of the turning path C3 is gourd-shaped, and the first ball passing portion 21 and the second ball passing portion 22 are based on two imaginary circles that partially overlap each other. In the first ball passing portion 21 and the second ball passing portion 22 of the turning path C3, two rows of balls 6 are arranged in a staggered pattern. When viewed from the traveling direction of the balls 6, adjacent balls 6 partially overlap each other. In the turning path C3, the balls 6 move while being pushed by the following balls 6, as in the return path C2. A gap is formed between the balls 6 and the first ball passing portion 21, and a gap is formed between the balls 6 and the second ball passing portion 22.

[0025] FIG. 6(a) shows two rows of balls 6 arranged on the turning path C3. FIG. 6(a) shows a perspective view of the turning path C3 of the circulating path 7 in the upper left of FIG. 2. Reference numeral 1 denotes a track member, reference numeral 4 denotes an inner plate, and reference numeral C3 denotes a turning path. FIG. 6(b) shows a first ball passing trajectory 41 and a second ball passing trajectory 42 of the first ball passing section 21 of the turning path C3. In this embodiment, the first ball passing trajectory 41 of the turning path C3 is represented by the center of the first ball passing section 21. Similarly, the second ball passing trajectory 42 of the turning path C3 is represented by the center of the second ball passing section 22 of the turning path C3. In the conventional motion guide device, the first ball passing trajectory and the second ball passing trajectory of the turning path are two-dimensional trajectories, whereas in the motion guide device of this embodiment, the first ball passing trajectory 41 and the second ball passing trajectory 42 of the turning path C3 are three-dimensional trajectories as described below. Reference numeral 43 in FIG. 6(b) denotes a ball center passing trajectory.

[0026] Fig. 7(a) shows the turning path C3 as viewed from a direction perpendicular to a plane P (a plane P including the center between the balls of the rolling path C1 and the center between the balls of the return path C2, see Fig. 2) that includes the rolling path C1 and the return path C2. Fig. 7(b) shows a front view of the turning path C3. Fig. 7(c) shows a side view of the turning path C3. Figs. 8(a), (b), and (c) show a first ball passing trajectory 41, a second ball passing trajectory 42, and a ball center trajectory 43 as viewed from the same direction as Figs. 7(a), (b), and (c).

[0027] As shown in FIG. 8(a), in the plan view of the turning path C3, the first ball passing locus 41 is disposed outwardly of the second ball passing locus 42 at the end Q1 on the rolling path C1 side and the end Q2 on the return path C2 side of the turning path C3. In other words, the inter-point distance L1 between the end Q1 and the end Q2 is greater for the first ball passing locus 41 than for the second ball passing locus 42. Also, the first ball passing locus 41 is disposed inwardly of the second ball passing locus 42 at the apex Q3 of the turning path C3. In other words, the protruding distance L2 between the apex Q3 of the first ball passing locus 41 and the second ball passing locus 42 is smaller for the first ball passing locus 41 than for the second ball passing locus 42.

[0028] As shown in Fig. 8(b) in a front view of the turning path C3, the first ball passing trajectory 41 and the second ball passing trajectory 42 are curved upwardly convexly. As shown in Fig. 8(c) in a side view of the turning path C3, the first ball passing trajectory 41 and the second ball passing trajectory 42 are curved upward from the ends Q1, Q2 toward the apex Q3 of the turning path C3. The perimeter of the first ball passing trajectory 41 and the perimeter of the second ball passing trajectory 42 of the turning path C3 are set to be substantially the same.

[0029] The first ball passing trajectory 41 and the second ball passing trajectory 42 of the turning path C3 are set, for example, as follows. As shown in Fig. 9(a), a rectangular virtual plate VP is prepared in which the length M1 of the short sides 61a, 61b is set to the distance M1 (see Fig. 8(b)) between the first ball passing trajectory 41 and the second ball passing trajectory 42 of the turning path C3, and the length M2 of the long sides 62a, 62b is set to the perimeter of the first ball passing trajectory 41 and the second ball passing trajectory 42 of the turning path C3. Then, as shown in Fig. 9(b), the short side 61a of this virtual plate VP is aligned with the end Q1 on the rolling path C1 side of the turning path C3, and the short side 61b is aligned with the end Q2 on the return path C2 side of the turning path C3, and the virtual plate VP is curved along the turning path C3. At this time, the shape of the long side 62a of the virtual plate VP is set to the first ball passing trajectory 41 of the turning path C3, and the shape of the long side 62b is set to the second ball passing trajectory 42 of the turning path C3. The shape of the virtual plate VP when curved along the turning path C3 can be obtained by the finite element method.

[0030] FIG. 10(a) shows balls 6 circulating on the turning path C3 of this embodiment. As shown in FIG. 10(a), on the turning path C3 of this embodiment, any ball 6 turning on the first ball passing section 21 comes into contact with the balls 6 before and after the first ball passing section 21. Similarly, any ball 6 turning on the second ball passing section 22 comes into contact with the balls 6 before and after the second ball passing section 22. On the turning path C3 and the return path C2, the ball 6 advances by being pushed by the balls 6 coming out of the rolling path C1, but on the turning path C3, any ball 6 comes into contact with the balls 6 before and after it, allowing smooth force transmission between the balls 6. The force transmission is indicated by arrows in the figure.

[0031] FIG. 10(b) shows the first ball passing section 21' and the second ball passing section 22' of the turning path C3' of the comparative example. In this turning path C3' of the comparative example, any ball 6' during a turn of the first ball passing section 21' does not come into contact with the balls 6' before or after the first ball passing section 21', but comes into contact with the ball 6' of the adjacent second ball passing section 22'. Then, the pushed ball 6' of the second ball passing section 22' pushes the ball 6' of the adjacent first ball passing section 21' in an oblique direction, and the pushed ball 6' of the first ball passing section 21' also pushes the ball 6' of the adjacent second ball passing section 22' in an oblique direction. This reduces the efficiency of force transmission between the balls 6'.

[0032] The effects of the motion guide device of this embodiment will be described below. By configuring the first ball passing trajectory 41 and the second ball passing trajectory 42 on the turning path C3 as described above, and setting the circumferential length of the first ball passing trajectory 41 and the circumferential length of the second ball passing trajectory 42 to be substantially the same, a motion guide device with smooth movement can be provided.

[0033] The first ball passing path 41 and the second ball passing path 42 of the turning path C3 are set to the shapes of the long sides 62a, 62b when a rectangular imaginary plate VP is curved along the turning path C3, so that the right-angled cross section of the turning path C3 can be made substantially the same at any position on the turning path C3. This makes it possible to provide a motion guide device with smooth movement.

[0034] Two rows of balls 6 are arranged in a staggered pattern in the first ball passing section 21 and the second ball passing section 22 adjacent to each other in the circulation path 7, thereby reducing waving. In addition, any ball 6 comes into contact with the balls 6 in front and behind it in the turning path C3, allowing smooth force transmission between the balls 6. Second embodiment

[0035] Fig. 11 shows a perpendicular cross-sectional view of a track member of a motion guide device of a second embodiment of the present invention. Fig. 12(a) shows a perpendicular cross-sectional view of the rolling path of a motion guide device of a second embodiment of the present invention, Fig. 12(b) shows a perpendicular cross-sectional view of the return path, and Fig. 12(c) shows a perpendicular cross-sectional view of the turning path. The configurations of the track member 1, carriage 2, carriage body 3, inner plate 4, end plate 5, and half pipes 8 and 9 are substantially the same as those of the motion guide device of the first embodiment, so the same reference numerals are used and their explanations are omitted.

[0036] In the motion guide device of the first embodiment, as shown in FIG. 3(b), in the return path C2, there is a gap between the first ball passing section 21 and the ball 6, and there is a gap between the second ball passing section 22 and the ball. Similarly, as shown in FIG. 3(c), in the turn path C3, there is a gap between the first ball passing section 21 and the ball 6, and there is a gap between the second ball passing section 22 and the ball. For this reason, when adjacent balls 6 separate on the return path C2 and the turn path C3, there are cases where adjacent balls 6 do not overlap partially when viewed from the traveling direction of the balls 6. In this case, there is a risk that the ball 6 in the first ball passing section 21 will overtake the ball in the second ball passing section 22.

[0037] In order to prevent this, in the motion guide device of the second embodiment, as shown in FIG. 12(b), the adjacent first ball passing portion 21 and the second ball passing portion 22 are shifted so as to approach each other in the return path C2. Then, the interval T2 between the adjacent first ball passing portion 21 and the second ball passing portion 22 in the return path C2 is made narrower than the interval T1 between the adjacent first ball passing portion 21 and the second ball passing portion 22 in the rolling path C1 shown in FIG. 12(a). Similarly, as shown in FIG. 12(c), the adjacent first ball passing portion 21 and the second ball passing portion 22 are shifted so as to approach each other in the turn path C3. Then, the interval T3 between the adjacent first ball passing portion 21 and the second ball passing portion 22 in the turn path C3 is made narrower than the interval T1 between the adjacent first ball passing portion 21 and the second ball passing portion 22 in the rolling path C1 shown in FIG. 12(a). T3 and T2 are equal.

[0038] In the motion guide device of the second embodiment, the first ball passing trajectory 41 on the turning path C3 is not represented by the center of the first ball passing section 21, but is represented by the passing trajectory of the ball 6 in the first ball passing section 21 when the adjacent balls 6 are located at positions apart from each other. The same is true for the second ball passing trajectory 42 on the turning path C3.

[0039] According to the motion guide device of the second embodiment, the following effects are achieved. On the return path C2 and the turn path C3, even if adjacent balls 6 move to positions apart, the adjacent balls 6 can be made to partially overlap each other when viewed from the traveling direction of the balls 6. Therefore, on the return path C2 and the turn path C3, the ball 6 on the first ball passing portion 21 can be prevented from overtaking the ball 6 on the second ball passing portion 22, and the staggered arrangement can be maintained.

[0040] It should be noted that the present invention is not limited to being embodied in the motion guide devices of the first and second embodiments, and can be embodied in other embodiments without departing from the gist of the present invention.

[0041] For example, in the first and second embodiments described above, the track member is straight and the motion guide device guides the linear motion of the movable body, but the track member may be curved and the motion guide device may guide the curved motion of the movable body.

[0042] In the above first embodiment, two rows of balls are arranged in a staggered pattern in the circulation path so that the two rows of balls overlap when viewed from the direction of travel, but the two rows of balls may also be arranged in the same phase in the circulation path so that the two rows of balls are separated when viewed from the direction of travel. [Explanation of symbols]

[0043] 1...race member, 2...carriage, 6...ball, 12...rolling portion of race member, 13...rolling portion of carriage, 21...first ball passing portion, 22...second ball passing portion, 41...first ball passing trajectory of turning path, 42...second ball passing trajectory of turning path, C1...rolling path, C2...return path, C3...turn path, P...plane including rolling path and return path, Q1...end of turning path on the rolling path side, Q2...end of turning path on the return path side, Q3...top of turning path, VP...imaginary plate, M1...length of short side of imaginary plate, M2...length of long side of imaginary plate, T1...interval between adjacent first ball passing portion and second ball passing portion of rolling path, T2...interval between adjacent first ball passing portion and second ball passing portion of return path, T3...interval between adjacent first ball passing portion and second ball passing portion of turning path

Claims

1. A raceway member having a rolling portion; a carriage having a rolling portion opposed to the rolling portion, a return path, and a turning path; In a motion guide device in which two rows of balls are arranged in adjacent first and second ball passing sections of a circulation path including a rolling path between the rolling portion of the track member and the rolling portion of the carriage, the return path, and the turn path, The two rows of balls are not retained by a retainer band; when viewed from a direction perpendicular to a plane including the rolling path and the return path, a first ball passing locus of the first ball passing portion is located outside a second ball passing locus of the second ball passing portion at an end portion of the turning path on the rolling path side and an end portion of the turning path on the return path side, and the first ball passing locus is located inside the second ball passing locus at an apex of the turning path, a motion guide device in which a perimeter of the first ball passage path on the turning path and a perimeter of the second ball passage path on the turning path are set to be substantially the same;

2. 2. The motion guide device according to claim 1, wherein the first ball passing trajectory and the second ball passing trajectory of the turning path are formed in a shape of a long side of a rectangular virtual plate, the short side of which is set to the distance between the first ball passing trajectory and the second ball passing trajectory of the turning path and the long side of which is set to the perimeter of the first ball passing trajectory and the second ball passing trajectory of the turning path, when the rectangular virtual plate is curved along the turning path.

3. 3. The motion guide device according to claim 1, wherein the two rows of balls are arranged in a staggered manner in the first ball passing portion and the second ball passing portion adjacent to each other in the circulation path.

4. The motion guide device according to claim 3, characterized in that the distance between adjacent first ball passing portions and second ball passing portions of the return path is narrower than the distance between adjacent first ball passing portions and second ball passing portions of the rolling path.

5. The motion guide device according to claim 3, characterized in that the distance between adjacent first ball passing portions and second ball passing portions of the turning path is narrower than the distance between adjacent first ball passing portions and second ball passing portions of the rolling path.

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