Ball screw actuator

Abstract

Lubricating oil can be smoothly supplied to a return passage without increasing the supply pressure of the lubricating oil. In a ball screw actuator (10), a slider (30) has: a slider body (32) including a ball screw nut part (100); and ball return members (36) attached to both ends of the slider body (32) in the axial direction, and a return passage (40) formed in the ball return members (36) having an outer end portion (40A) communicating with an outer passage (74) of the balls (72) and an inner end portion (40B) communicating with an inner passage (76) of the balls (72). The lubricating oil supply passage (44) communicates with the return passage (40) closer to the outer end (40A) than to the inner end (40B).

Description

Technical Field

[0001] The present invention relates to a ball screw actuator, and more particularly, to a lubricating oil supply structure for a linear ball bearing assembled in the ball screw actuator. Background Art

[0002] As a linear motion actuator, the following ball screw actuator is known, which comprises: a guide rail having left and right side walls, the guide rail being linear with a concave cross-section; left and right linear ball bearings, each of which comprises a slider disposed between the left and right side walls of the guide rail and a plurality of balls circulating between the left and right side walls of the guide rail and the slider, guiding the axial movement of the slider relative to the guide rail; a ball screw nut portion disposed on the slider; and a ball screw shaft that axially extends through a through hole disposed in the slider and screws into the ball screw nut portion disposed on the slider via the balls (for example, Patent Document 1). The slider disposed in this ball screw actuator comprises: a slider body that holds the ball screw nut portion; and a ball return member mounted at both ends of the slider body in the axial direction, having return paths for the left and right linear ball bearings.

[0003] In the above-mentioned ball screw actuator, the structure for supplying lubricating oil such as grease to the left and right linear ball bearings includes: a lubricating oil injection passage, which is provided in the ball return component; and a lubricating oil supply passage, which supplies lubricating oil from the lubricating oil injection passage to the return passages of the left and right linear ball bearings.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 4-115842 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] Regarding the supply of lubricating oil to the return passage, if the pressure (internal pressure) of the lubricating oil in the return passage is high, the lubricating oil has difficulty entering the return passage, and the supply pressure of the lubricating oil needs to be increased.

[0009] An object of the present invention is to smoothly supply lubricating oil to a return passage without increasing the supply pressure of the lubricating oil.

[0010] Technical means to solve problems

[0011] In order to solve the above-mentioned problems, one embodiment of the present invention is a ball screw actuator comprising: a guide rail having left and right side walls, the guide rail being a straight line with a concave cross-section; a slider arranged between the left and right side walls of the guide rail; left and right linear ball bearings, the left and right linear ball bearings having a plurality of balls circulating between the left and right side walls of the guide rail and the slider, guiding the movement of the slider relative to the axial direction of the guide rail; a ball screw nut portion, which is arranged on the slider; and a ball screw shaft, which passes through a through hole provided in the slider along the axial direction and is screwed with the ball screw nut portion provided on the slider via the balls, wherein the slider comprises: a slider body including the ball screw nut portion; and a ball return component mounted on the slider body. At both ends of the body in the axial direction, the left and right linear ball bearings each have: an external passage, which is formed by the corresponding side wall of the guide rail and the slider body; and an internal passage, which is formed in the interior of the slider body in a manner extending along the axial direction, and at least one of the ball return components has: left and right return passages, the left and right return passages for the movement of each ball of the left and right linear ball bearings; a lubricating oil injection passage; and a lubricating oil supply passage, which supplies lubricating oil from the lubricating oil injection passage to the left and right return passages, the left and right return passages each having an outer end connected to the corresponding external passage and an inner end connected to the corresponding internal passage, the lubricating oil supply passage being connected to the left and right return passages on the side closer to the outer end than to the inner end.

[0012] According to this aspect, the lubricating oil can be smoothly supplied to the return passage without increasing the supply pressure of the lubricating oil.

[0013] In the above aspect, it is preferable that the lubricating oil supply passage communicate with the left and right return passages at the outer end portion.

[0014] According to this aspect, the lubricating oil can be supplied to the return passage more smoothly without increasing the supply pressure of the lubricating oil.

[0015] In the above method, it is preferred or also possible that the left and right linear ball bearings are each constructed as two levels, the ball return component has a return passage at the upper and lower levels, and the lubricating oil supply passage reaches between the return passages of the upper and lower levels and is connected to the return passages of the upper and lower levels.

[0016] According to this aspect, the lubricating oil can be smoothly supplied to the return passages of the left and right upper and lower linear ball bearings without increasing the supply pressure of the lubricating oil.

[0017] In the above method, it is preferred or possible that the ball screw actuator includes a path demarcating component, which is installed on the ball return component and extends in a manner of spanning the upper and lower return paths, thereby demarcating the upper and lower return paths including the outer end and the inner end, and a portion of the lubricating oil supply path is formed in the path demarcating component.

[0018] According to this aspect, the structure of the lubricating oil supply passage does not become complicated.

[0019] In the above aspect, preferably, the portion of the lubricating oil supply passage is formed by a groove formed in the passage defining member.

[0020] According to this aspect, the lubricating oil supply passage can be easily formed.

[0021] In the above aspect, it is preferable or desirable that the lubricating oil supply passage opens from the passage defining member to the return passages at two upper and lower stages, with the openings facing outward.

[0022] According to this aspect, lubricating oil can be accurately and evenly supplied to each of the upper and lower external passages.

[0023] Effects of the Invention

[0024] According to the ball screw actuator of the present invention, the lubricating oil can be smoothly supplied to the return passage without increasing the supply pressure of the lubricating oil. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a perspective view showing a first embodiment of the ball screw actuator of the present invention.

[0026] Figure 2 This is an enlarged exploded perspective view of the main parts of the ball screw actuator according to the first embodiment.

[0027] Figure 3 This is a perspective view of the main part of the ball return member of the ball screw actuator according to the first embodiment.

[0028] Figure 4 This is a perspective view of a main portion of the partition wall member of the ball screw actuator according to the first embodiment.

[0029] Figure 5 This is a front view of the ball return member of the ball screw actuator according to the first embodiment.

[0030] Figure 6 It is along Figure 5 A sectional view taken along line VI-VI.

[0031] Figure 7This is a skeleton diagram schematically showing the linear ball bearing and lubricating oil passage of the ball screw actuator according to the first embodiment.

[0032] Figure 8 It is a perspective view showing a second embodiment of the ball screw actuator of the present invention.

[0033] Figure 9 This is a perspective view of a ball return member of a ball screw actuator according to a second embodiment.

[0034] Figure 10 This is a front view of a ball return member of a ball screw actuator according to a second embodiment. DETAILED DESCRIPTION

[0035] Preferred embodiments of the present invention will be described with reference to the accompanying drawings.

[0036] (Implementation 1)

[0037] Reference Figures 1 to 7 The ball screw actuator 10 according to the first embodiment will be described. Figure 7 This is a skeleton diagram schematically showing a ball circulation path and a lubricating oil passage of a linear ball bearing, and illustration of a slider 30 and a side wall 22 to be described later is omitted.

[0038] like Figure 1 As shown, the ball screw actuator 10 of the first embodiment includes: a guide rail 20 having left and right side walls 22, the guide rail 20 being a straight line with a concave cross-sectional shape; a slider 30, which is arranged between the left and right side walls 22 of the guide rail 20; and left and right linear ball bearings 70, the left and right linear ball bearings 70 having a plurality of balls 72 circulating between the left and right side walls 22 of the guide rail 20 and the slider 30 (see Figure 7 ), guiding the movement of the slider 30 relative to the axial direction of the guide rail 20.

[0039] The ball screw actuator 10 further comprises: a ball screw nut portion 100, which is provided on the slider 30; and a ball screw shaft 102, which passes through the through hole 31 provided on the slider 30 along the axial direction, via the ball 104 (refer to Figure 6 ) is screwed together with the ball screw nut portion 100 provided on the slider 30. The ball screw shaft 102 is rotationally driven by an electric motor (not shown) mounted on the shaft end of the guide rail 20. In addition, the ball screw nut portion 100 can also be constructed as an integral unit with the slider 30.

[0040] The slider 30 includes a substantially rectangular slider body 32 including a ball screw nut portion 100 and substantially rectangular front and rear ball return members 36 fixed to both ends (front and rear ends) of the slider body 32 in the axial direction by a plurality of bolts 34 .

[0041] like Figure 2 and Figure 5 As shown, each ball return member 36 has a through hole 38 that penetrates substantially the center portion in the axial direction and forms a portion of the through hole 31 described above. Figure 6 As shown, the through hole 38 has an inner diameter substantially the same as or smaller than that of the through hole 31A of the through hole 31 that passes through the slider body 32 , and is provided substantially coaxially (substantially concentrically) with the through hole 31A.

[0042] Each ball return member 36 further comprises: left and right return passages 40, which are symmetrically arranged with respect to the through hole 38, and allow the balls 72 of the left and right linear ball bearings 70 to move in a rolling manner; a lubricating oil injection passage 42, which extends in the axial direction and is arranged to be biased to one of the left and right sides with respect to the through hole 38; and a lubricating oil supply passage 44, which supplies lubricating oil such as grease from the lubricating oil injection passage 42 to the left and right return passages 40. A lubricating oil joint 46 (see FIG. 1 ) is mounted on the outer wall of each ball return member 36 and communicates with the corresponding lubricating oil injection passage 42. Figure 1 and Figure 7 ).

[0043] As explained in detail later Figure 7 As shown, the left and right linear ball bearings 70 each have an external passage 74 that is located on the corresponding side wall 22 of the guide rail 20 (see FIG. Figure 1 ) and the slider body 32 (refer to Figure 1 ) is formed between the slider body 32 (reference) in an axial direction extending manner; and an internal passage 76, which is formed between the slider body 32 (reference Figure 1 ) is formed in such a way that the interior thereof extends (penetrates) in the axial direction. Each external passage 74 is formed by a groove 24 (see FIG. 2 ) having a substantially semicircular cross section formed on the inner side surface of the side wall 22. Figure 1 ) and a groove (not shown) of a substantially semicircular cross section formed on the outer side surface of the slider body 32. The inner side surface of the side wall 22 does not contact the outer side surface of the slider body 32, and an air gap G having a gap width in the left-right direction and extending in the axial direction is formed between the inner side surface of the side wall 22 and the outer side surface of the slider body 32 (see Figure 5 ).

[0044] like Figure 2 and Figure 5As shown, the left and right return passages 40 are each substantially semicircular (U-shaped) passages in a plan view, defined by a groove 41 and a passage-defining member 43, each of which allows the balls 72 to roll. The groove 41 is formed in the ball return member 36 and has a substantially semicircular plan view, while the passage-defining member 43 is attached to the ball return member 36 and has a substantially semicircular plan view. Each return passage 40 has an outer end 40A that communicates with the corresponding outer passage 74 and an inner end 40B that communicates with the corresponding inner passage 76.

[0045] Each ball return component 36 protrudes outward from the left and right outer walls to form a ball fall-off prevention portion 39, which has a roughly semicircular cross-sectional shape and is used to prevent the balls 72 of the linear ball bearing 70 from falling outward from the outer end portions 40A of the left and right return passages 40.

[0046] In the left and right linear ball bearings 70 , a closed-loop circulation path through which a plurality of balls 72 circulates is formed by the mutually communicating external passages 74 , internal passages 76 , and front and rear return passages 40 .

[0047] The lubricating oil supply passage 44 includes a first passage 48. Figure 5 and Figure 7 When observed from the middle, the first passage 48 extends to the right from the lubricating oil injection passage 42 and reaches a branch position B on the left-right symmetry line A that passes through the center of the through hole 38 and extends in the up-down direction; and the left-side second passage 50 and the right-side second passage 52 are symmetrical on the left and right, and the left-side second passage 50 and the right-side second passage 52 branch to the left and right from the branch position B and reach the left and right return passages 40.

[0048] The left second passage 50 includes a leftward extension portion 50A extending leftward from a branching point B, and an inclined extension portion 50B that bends obliquely downward from the left end of the leftward extension portion 50A to reach the left return passage 40. The inclined extension portion 50B includes a connecting end 50C that connects to a portion near the left outer end 40A of the return passage 40.

[0049] The communication end 50C only needs to be opened at a position closer to the outer end 40A side than the position that divides the inner end 40B and the outer end 40A into two equal parts in the left return passage 40. The communication end 50C is preferably as follows Figure 5 As shown by the imaginary line, the return passage 40 communicates with the left outer end portion 40A of the air gap G closest to the left outer passage 74 .

[0050] The right second passage 52 includes a rightward extension portion 52A extending rightward from the branching position B, and an inclined extension portion 52B that bends obliquely downward from the right end of the rightward extension portion 52A to reach the right return passage 40. The inclined extension portion 52B includes a connecting end 52C that connects to the return passage 40 near the right outer end 40A.

[0051] The communication end 52C only needs to be opened at a position closer to the outer end 40A than the position that divides the inner end 40B and the outer end 40A into two equal parts in the right return passage 40. The communication end 52C is preferably as follows Figure 5 As shown by the imaginary line, the return passage 40 communicates with the right outer end portion 40A of the air gap G closest to the right outer passage 74 .

[0052] The left second passage 50 and the right second passage 52 are bilaterally symmetrical with respect to the bilateral symmetry line A, and their passage lengths are equal to each other.

[0053] The lubricating oil supply passage 44 further includes a left third passage 54 and a right third passage 56, which extend vertically and symmetrically from the left second passage 50 and the right second passage 52 radially outward of the through-hole 38; and a fourth passage 58, which extends horizontally and interconnects the lower ends of the left third passage 54 and the right third passage 56. The fourth passage 58 includes an open end 58A that opens toward the lower portion of the through-hole 38, and the fourth passage 58 reaches the through-hole 38.

[0054] The first passage 48, the left second passage 50, the right second passage 52, the left third passage 54, the right third passage 56, and the fourth passage 58 include portions formed by grooves opening into the surface of the ball return member 36 that contacts the end surface of the slider body 32. The openings of these grooves are closed by the end surface of the slider body 32, thereby defining lubricating oil supply passages having a closed cross-sectional shape. This facilitates the design of lubricating oil supply passages with a high degree of flexibility.

[0055] The first passage 48 and the left extension 50A of the left second passage 50 include portions that overlap each other in the front and rear directions of the axial direction. The portions that overlap each other between the first passage 48 and the left extension 50A of the left second passage 50 are separated by a partition wall member 60 (see Figure 4 ) isolating to form a separate passage, wherein the partition wall member 60 (refer to Figure 4 ) is fitted into the recess 62 formed in the ball return member 36 (see Figure 3 )middle.

[0056] The details of the isolation structure are described below. Figure 3As shown, the recess 62 of the ball return member 36 includes a deep bottom surface 62A into which the lubricating oil injection passage 42 opens, and a shallow bottom surface 62B formed on a portion of the outer periphery of the deep bottom surface 62A. The partition wall member 60 contacts the shallow bottom surface 62B, and the first passage 48 is defined between the back surface of the partition wall member 60 and the deep bottom surface 62A. The recess 62 formed by the deep bottom surface 62A includes a portion extending to the right beyond the branch position B (see FIG. 1 ). Figure 5 ) portion, the first passage 48 also extends in the same direction. The partition wall member 60 has a left-right dimension that does not exceed the branching position B at the right end, so the first passage 48 opens toward the base end at the branching position B to the left second passage 50 and the right second passage 52.

[0057] like Figure 4 As shown, the portion of the leftward extension 50A of the left second passage 50 that overlaps with the first passage 48 is formed by a groove 50D formed on the surface of the partition wall member 60. A groove 54A is formed on the surface of the partition wall member 60, and this groove 54A serves as a branch end of the left third passage 54 that branches from the left second passage 50.

[0058] This structure prevents interference between the axially overlapping portions of the first passage 48 and the leftward extending portion 50A of the leftward second passage 50. Furthermore, the axially overlapping portions of the first passage 48 and the leftward extending portion 50A of the leftward second passage 50 can be easily formed without requiring any special methods.

[0059] The left second passage 50, the right second passage 52, the left third passage 54, the right third passage 56 and the fourth passage 58 include portions that cooperate with each other to surround the radially outer side of the through hole 38. Figure 2 、 Figure 5 as well as Figure 6 As shown, a sealing plate 64 is attached to the surface of the ball return member 36 that contacts the end surface of the slider body 32. This sealing plate 64 covers the openings of the grooves of the portions of the left second passage 50, the right second passage 52, the left third passage 54, the right third passage 56, and the fourth passage 58 that surround the through-hole 38, relative to the aforementioned surface of the slider body 32. The sealing plate 64 has an opening 68 that is substantially concentric with the through-hole 31 (31A, 38), and the inner diameter of the opening 68 is smaller than the inner diameter of the through-hole 31.

[0060] The ball return member 36 has a shelf portion 36A formed at a portion where the sealing plate 64 is mounted (see FIG. Figure 2 ), the shelf portion 36A has the same depth as the thickness of the sealing plate 64, and the shelf portion 36A is embedded in the outer peripheral edge of the sealing plate 64, and the surface of the slider body 32 that is connected to the end face of the slider body 32 includes a portion of the sealing plate 64 and becomes the same surface.

[0061] According to the above-mentioned structure, the lubricating oil injected into the lubricating oil injection passage 42 flows through the first passage 48 and reaches the branch position B on the left-right symmetry line A of the through hole 38, and flows from the branch position B through the left-right symmetrical second passage 50 and the right-right second passage 52 and is supplied from the connecting ends 50C and 52C to the return passage 40 of the left and right linear ball bearings 70.

[0062] Since the lubricating oil injected into the lubricating oil injection passage 42 temporarily flows to the branch position B through the first passage 48, most of the lubricating oil flows through the left second passage 50 and the right second passage 52 which are symmetrical on the left and right and are supplied to the return passages 40 of the left and right linear ball bearings 70. Therefore, even if the lubricating oil injection passage 42 is biased to one side in the left-right direction relative to the branch position B, the lubricating oil from the lubricating oil injection passage 42 can be evenly supplied to the return passages 40 of the left and right linear ball bearings 70.

[0063] That is, since the left second passage 50 and the right second passage 52 are symmetrical with respect to the left-right symmetry line A, and the lengths of their respective passages are equal to each other, even if the lubricating oil injection passage 42 is biased to one side in the left-right direction relative to the branch position B, the left and right linear ball bearings 70 can be lubricated with lubricating oil evenly on the left and right.

[0064] By deviating the lubricating oil injection passage 42 to one side in the left-right direction relative to the branch position B, the distance between the upper edge of the through hole 31 (31A, 38) of the slider 30 including the ball return member 36 and the upper edge (upper surface) of the slider 30 can be reduced compared to the case where the lubricating oil injection passage 42 is located at the branch position B. As a result, the height dimension H of the slider 30 can be reduced (see Figure 5 ), thereby achieving miniaturization of the ball screw actuator 10 in the vertical direction.

[0065] Of the outer end 40A and inner end 40B of the return passage 40, the outer end 40A is closest to the air gap G of the external passage 74 and is located on the side open to the atmosphere. Consequently, the lubricating oil pressure at the outer end 40A is lower than that at the inner end 40B. In other words, the lubricating oil pressure in the return passage 40 is lower on the outer end 40A side than on the inner end 40B side.

[0066] The communicating ends 50C and 52C of the left second passage 50 and the right second passage 52 with respect to the corresponding return passage 40 communicate with a portion of the return passage 40 that is closer to the outer end 40A side at a position that bisects the distance between the inner end 40B and the outer end 40A of the return passage 40. This structure of the left second passage 50 and the right second passage 52 allows lubricating oil to be supplied to the return passage 40 on the lower-pressure side, where the lubricating oil pressure (internal pressure) is lower than that at the inner end 40B.

[0067] Thus, compared with the case where lubricating oil is supplied to the return passage 40 on the inner end portion 40B side, lubricating oil can be smoothly supplied to the return passage 40 without increasing the injection pressure of the lubricating oil, thereby improving the lubricating oil supply workability.

[0068] The internal pressure of the lubricating oil in the return passage 40 is lowest at the outer end portion 40A closest to the air gap G of the external passage 74. Therefore, in order to smoothly supply the lubricating oil to the return passage 40, it is preferable that the communicating ends 50C and 52C are as follows: Figure 5 As shown by the imaginary line, it communicates with the outer end portion 40A.

[0069] The ratio of the connecting ends 50C and 52C of the left second passage 50 and the right second passage 52 relative to the corresponding return passage 40 to the return passage 40 connects the position where the inner end 40B and the outer end 40A of the return passage 40 are divided into two equal parts, and the position is close to the outer end 40A side, thereby supplying lubricating oil to the return passage 40 where the lubricating oil pressure (internal pressure) is lower than the lubricating oil pressure of the inner end 40B.

[0070] Thus, compared with the case where lubricating oil is supplied to the return passage 40 on the inner end portion 40B side, lubricating oil can be smoothly supplied to the return passage 40 without increasing the injection pressure, thereby improving the lubricating oil supply workability.

[0071] In order to smoothly supply the lubricating oil in accordance with the internal pressure, it is preferred that the communicating ends 50C and 52C are as follows: Figure 5 As shown by the imaginary line, it communicates with the outer end 40A of the air gap G closest to the corresponding external passage 74.

[0072] A portion of the lubricating oil injected into the lubricating oil injection passage 42 temporarily flows to the branch position B through the first passage 48, then flows through the left second passage 50, the right second passage 52, the left third passage 54, the right third passage 56 and the fourth passage 58, and flows out from the opening end 58A to the through hole 38.

[0073] As a result, the lubricating oil is applied to the outer peripheral surface of the portion of the ball screw shaft 102 that passes through the through hole 38 , thereby lubricating the ball screw shaft 102 .

[0074] like Figure 6 As shown, the inner diameter of the opening 68 through the sealing plate 64 is smaller than the inner diameter of the through hole 31A of the slider 30, as shown in FIG. Figure 6 As shown, the sealing plate 64 functions as a barrier separating the through-hole 31A from the through-hole 38, thereby preventing the lubricating oil flowing from the open end 58A of the fourth passage 58 into the through-hole 38 from flowing toward the through-hole 31A. In other words, the lubricating oil supplied to the through-hole 38 of the ball return member 36 can be prevented from excessively flowing toward the slider body 32. This prevents the lubricating oil from flowing excessively toward the ball screw nut portion 100 within the slider body 32, thereby reducing unnecessary consumption of lubricating oil.

[0075] (Implementation Method 2)

[0076] Reference Figures 8 to 10 The ball screw actuator 10 according to the second embodiment will be described. Figures 8 to 10 In, with Figures 1 to 9 The corresponding parts are marked with Figures 1 to 9 The same reference numerals as those in the figure are used and their descriptions are omitted.

[0077] In the ball screw actuator 10 of the second embodiment, the left and right linear ball bearings 70 are each constructed in two stages, one above the other. Each ball return member 36 has return passages 40 at both upper and lower levels. The inclined extension 50B of the left second passage 50 and the inclined extension 52B of the right second passage 52 are each symmetrically formed, including a portion formed by the groove 43A formed in the corresponding passage-defining member 43. These portions extend between the upper and lower return passages 40 and communicate with the upper and lower return passages 40 via outwardly open, upper and lower symmetrical communication ends 50C and 52C.

[0078] The passage defining member 43 extends vertically across the upper and lower return passages 40 , and defines the upper and lower return passages 40 including the outer end portion 40A and the inner end portion 40B.

[0079] The connecting ends 50C and 52C of the inclined extension portion 50B of the left second passage 50 and the inclined extension portion 52B of the right second passage 52 respectively open to the upper and lower return passages 40 from the position of the passage defining member 43 located in the middle of the upper and lower return passages 40, and the openings face outward.

[0080] In the second embodiment, the lubricating oil injected into the lubricating oil injection passage 42 flows through the first passage 48 and reaches the branch position B on the left-right symmetry line A of the through hole 38, flows from the branch position B through the left-right symmetric second passage 50 and the right-right second passage 52, and is supplied to the respective return passages 40 of the upper and lower linear ball bearings 70 from the connecting ends 50C and 52C that are symmetric with respect to the upper and lower return passages 40.

[0081] Thus, even if the lubricating oil injection passage 42 is offset to one side in the left-right direction relative to the branch position B, lubricating oil can be supplied evenly vertically and evenly horizontally to the linear ball bearings 70 in both upper and lower stages.

[0082] The inclined extension portion 50B of the left second passage 50 and a portion of the inclined extension portion 52B of the right second passage 52, in detail, the inclined extension portion 50B and the inclined extension portion 52B respectively cross the portion of the upper return passage 40 up and down, and are formed by the groove 43A formed in the passage defining component 43, so the structure of the inclined extension portion 50B and the inclined extension portion 52B will not become complicated, and the formation of this portion becomes easy.

[0083] Preferred embodiments of the present invention have been described above. However, as those skilled in the art can easily understand, the present invention is not limited to these embodiments and can be modified appropriately without departing from the spirit of the present invention.

[0084] For example, the partition wall separating the overlapping portions of the first passage 48 and the leftward extension 50A of the left second passage 50 in the axial direction may be formed integrally with the ball return member 36 by molding, rather than by the partition wall member 60. The lubricating oil supply passage 44 does not necessarily need to be bilaterally symmetrical. The lubricating oil supply structure for the linear ball bearing 70, including the lubricating oil supply passage 44, does not necessarily need to be formed in the ball return member 36 at both ends of the slider body 32 in the axial direction. It may be formed in only one of the two end ball return members 36.

[0085] The lubricating oil supply structure of the linear ball bearing 70, including the first passage 48, the left second passage 50 and the right second passage 52, is not limited to being applied to the linear ball bearing 70 of the slider 30 of the ball screw actuator 10, but can also be applied to the lubricating oil supply structure of a pair of left and right linear ball bearings 70 of a linear guide device in which the slider 30 is driven by a linear motor or the like, other than the case where the slider 30 is driven by the ball screw actuator 10.

[0086] Furthermore, not all of the components shown in the above-mentioned embodiments are essential, and they can be appropriately selected or omitted without departing from the gist of the present invention.

[0087] Label Description

[0088] 10: Ball screw actuator; 20: Guide rail; 22: Side wall; 24: Groove; 30: Slider; 31: Through hole; 31A: Through hole; 32: Slider body; 34: Bolt; 36: Ball return member; 36A: Shelf; 38: Through hole; 39: Ball fall-off prevention member; 40: Return passage; 40A: Outer end; 40B: Inner end; 41: Groove; 42: Lubricant injection passage; 43: Passageway demarcating member; 43A: Groove; 44: Lubricant supply passage; 46: Lubricant joint; 48: First passage; 50: Second passage on the left side; 50A: Left extension; 50B: Inclined extension; 50 C: connecting end; 50D: groove; 52: second passage on the right; 52A: right extension; 52B: inclined extension; 52C: connecting end; 54: third passage on the left; 54A: groove; 56: third passage on the right; 58: fourth passage; 58A: opening end; 60: partition wall component; 62: recess; 62A: deep bottom surface; 62B: shallow bottom surface; 64: sealing plate; 68: opening; 70: linear ball bearing; 72: ball; 74: external passage; 76: internal passage; 100: ball screw nut part; 102: ball screw shaft; 104: ball; A: left-right symmetry line; B: branch position; G: air gap.

Claims

1. A ball screw actuator comprising: a guide rail having left and right side walls, the guide rail being in a straight line shape with a concave cross-sectional shape; a slider disposed between the left and right side walls of the guide rail; Left and right linear ball bearings, each having a plurality of balls circulating between the left and right side walls of the guide rail and the slider, and guiding the movement of the slider in the axial direction relative to the guide rail; a ball screw nut portion, which is provided on the slider; and The ball screw shaft is inserted into the through hole provided in the slider along the axial direction and is screwed with the ball screw nut provided in the slider via balls. in, The slider has: a slider body including the ball screw nut portion; and The ball return components are mounted on both ends of the slider body in the axial direction. The left and right linear ball bearings each have: an external passage formed by corresponding side walls of the guide rail and the slider body; and An internal passage is formed inside the slider body so as to extend in the axial direction. At least one of the ball return components has: Left and right return passages for allowing the balls of the left and right linear ball bearings to move; lubricating oil injection passage; and a lubricating oil supply passage for supplying lubricating oil from the lubricating oil injection passage to the left and right return passages; Each of the left and right return passages has an outer end communicating with the corresponding external passage and an inner end communicating with the corresponding The lubricating oil supply passage communicates with the left and right return passages on a side closer to the outer end portion than to the inner end portion.

2. The ball screw actuator according to claim 1, wherein: The lubricating oil supply passage communicates with the left and right return passages at the outer end portions.

3. The ball screw actuator according to claim 1 or 2, wherein: The left and right linear ball bearings are each configured in two stages, the ball return member having return passages in the upper and lower stages, and the lubricating oil supply passage reaches between the return passages in the upper and lower stages and communicates with the return passages in the upper and lower stages.

4. The ball screw actuator according to claim 3, wherein: The ball screw actuator includes a passage defining component, which is mounted on the ball return component and extends vertically across the upper and lower return passages, thereby defining the upper and lower return passages including the outer end portion and the inner end portion. A portion of the lubricating oil supply passage is formed in the passage defining member.

5. The ball screw actuator according to claim 4, wherein: The portion of the lubricating oil supply passage is formed by a groove formed in the passage defining member.

6. The ball screw actuator according to claim 4, wherein: The lubricating oil supply passage opens from the passage defining member to the return passages at two upper and lower stages, and the openings face outward.

Images