JP2016211697A - Ball screw nut, ball screw mechanism and actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a downsized ball screw nut, a ball screw mechanism and an actuator.SOLUTION: A ball screw nut includes a ball screw nut body, and a U-shaped pipe installed on the outer periphery of the ball screw nut body and constituting a part of a non-load circulation passage for a rolling body. With this constitution, the ball screw nut body is downsized, and a projection amount of the non-load circulation passage to the outside of the ball screw nut body is reduced. Consequently, not only the ball screw nut, but also a slider and an actuator can be downsized.SELECTED DRAWING: Figure 2

Description

  The present invention relates to, for example, a ball screw nut used for reciprocal movement of a slider, a ball screw mechanism using the ball screw nut, and an actuator using the ball screw mechanism, and in particular, can be miniaturized. It relates to something that was devised.

The conventional ball screw mechanism has a configuration as shown in FIG. That is, the ball screw mechanism 101 includes a ball screw 103 and a ball screw nut 105 penetrated by the ball screw 103.
The ball screw 103 is formed with spiral grooves 107a, 107b, 107c, 107d, 107e, and 107f.
The ball screw nut 105 includes a nut main body 109 and end deflectors 111 and 111 installed at both ends of the nut main body 109. The nut body 109 is a substantially hollow cylindrical member, and a through hole 113 is formed through the ball screw 103. On the inner peripheral surface of the through hole 113, spiral grooves 115a, 115b, and 115c are formed. Further, as shown in FIG. 12B, the nut body 109 is formed with no-load circulation paths 117a, 117b, and 117c.
The end deflectors 111 and 111 each have three return paths (not shown).

  A space between the spiral groove 107a of the ball screw 103 and the spiral groove 115a of the nut body 109, a return path (not shown) of the end deflectors 111 and 111, and a no-load circulation path 117a of the nut body 109. Inside, a plurality of steel balls 119a roll and circulate. Similarly, a space between the spiral groove 107c of the ball screw 103 and the spiral groove 115b of the nut body 109, a return path (not shown) of the end deflectors 111 and 111, and an unloaded circulation path of the nut body 109 A plurality of steel balls 119b also roll and circulate in 117b, and a space between the spiral groove 107e of the ball screw 103 and the spiral groove 115c of the nut body 109, and the end deflectors 111 and 111 A plurality of steel balls 119c roll and circulate also in the return path (not shown) and the no-load circulation path 117c of the nut body 109.

By connecting a motor (not shown) to one end of the ball screw 103, fixing a slider (not shown) to the ball screw nut 105, and providing a guide mechanism for restricting the rotation of the slider (not shown) and the ball screw nut 105, An actuator is configured.
When the ball screw 103 is rotated and driven by the motor (not shown), the ball screw nut 105 and the slider (not shown) are moved in the axial direction of the ball screw 103.

However, in the ball screw mechanism 101 having such a configuration, since the no-load circulation paths 117a, 117b, and 117c are formed in the nut body 109 of the ball screw nut 105, the diameter of the nut body 109 must be increased. As a result, downsizing of the ball screw mechanism 101 and the actuator is hindered.
Therefore, it is conceivable to reduce the diameter of the nut body 109 by providing a no-load circulation path outside the nut body 109 of the ball screw nut 105, thereby reducing the size of the ball screw mechanism 101 and the actuator. ing.
Examples of disclosing such a configuration include Patent Document 1 and Patent Document 2.

Japanese Patent No. 5252279 JP 2006-342976 A

The conventional configuration has the following problems.
First, in the ball screw mechanism described in Patent Document 1, a cylindrical portion provided with a second passage portion on which a steel ball rolls is installed on the outer peripheral side of the displacement nut, thereby reducing the diameter of the displacement nut. Although miniaturization was attempted, further miniaturization was required.
Similarly, in the case of the ball screw device described in Patent Document 2, a cylindrical communication passage piece is installed on the outer peripheral side of the nut member, thereby reducing the diameter and size of the nut member. In the same way, further miniaturization has been demanded.

  The present invention has been made based on such points, and an object of the present invention is to provide a ball screw nut, a ball screw mechanism, and an actuator that can be reduced in size.

In order to achieve the above object, a ball screw nut according to claim 1 of the present invention includes a ball screw nut main body and a U-shaped tube which is installed on the outer periphery of the ball screw nut main body and constitutes a part of a no-load circuit of a rolling element. It is characterized by comprising.
Further, the ball screw nut according to claim 2 is the ball screw nut according to claim 1, wherein the ball screw nut main body has communication recesses for guiding the rolling elements circulating inside to the U-shaped pipe at both ends. The formed concave end deflectors are installed, and both the end deflectors and the U-shaped pipe constitute the no-load circulation path.
According to a third aspect of the present invention, there is provided the ball screw nut according to the second aspect, wherein the end deflector is prevented from being detached in the axial direction between the end deflector and the ball screw nut main body. Is provided.
The ball screw nut according to claim 4 is the ball screw nut according to claim 2 or claim 3, wherein the U-shaped tube is a single part, and the no-load circuit is a single U-shaped tube. It consists of three parts of the end deflectors at both ends.
A ball screw nut according to claim 5 is the ball screw nut according to claim 2 or claim 3, wherein the U-shaped tube is divided into two in the longitudinal direction, and one is integrated with one of the both end deflectors. The other is integrated with the other of the two end deflectors, and the no-load circuit is composed of these two parts.
A ball screw nut according to claim 6 is the ball screw nut according to claim 2 or claim 3, wherein the end deflectors are respectively integrated at both ends of the U-shaped tube, and the no-load circuit is one component. It is characterized by comprising.
A ball screw nut according to a seventh aspect is the ball screw nut according to any one of the second to sixth aspects, wherein a plurality of the no-load circulation paths are provided, and the end deflector includes the individual A communication concave portion corresponding to the no-load circulation path is formed.
The ball screw nut according to claim 8 is the ball screw nut according to claims 1 to 7, wherein a groove for an unloaded circuit is provided on an outer periphery of the ball screw nut body corresponding to the U-shaped tube. It is characterized by that.
According to a ninth aspect of the present invention, there is provided a ball screw mechanism comprising: the ball screw nut according to any one of the first to eighth aspects; and a ball screw screwed and disposed on the ball screw nut. It is a feature.
An actuator according to a tenth aspect is characterized in that the slider is movably arranged using the ball screw mechanism according to the ninth aspect.

As described above, according to the ball screw nut according to claim 1 of the present invention, the ball screw nut main body and the U-shape that is installed on the outer periphery of the ball screw nut main body and constitutes a part of the no-load circuit of the rolling element. The diameter of the ball screw nut body can be reduced, and the use of the U-shaped pipe reduces the amount of protrusion of the no-load circuit to the outside of the ball screw nut body. Thus, the size can be reduced.
Further, according to the ball screw nut according to claim 2, in the ball screw nut according to claim 1, a communication recess for guiding the rolling elements circulating inside to the U-shaped pipes at both ends of the ball screw nut main body. In order to configure the no-load circulation path by these end deflectors and the U-shaped pipe, for example, it is necessary to provide a tubular configuration in which the rolling elements circulate. The above-described no-load circuit can be configured with a simple configuration.
According to a ball screw nut according to claim 3, in the ball screw nut according to claim 2, the engagement between the end deflector and the ball screw nut main body prevents the end deflector from being detached in the axial direction. Since the portion is provided, for example, the falling off of the end deflector due to the movement of the rolling elements can be prevented.
According to a ball screw nut according to claim 4, in the ball screw nut according to claim 2 or claim 3, the U-shaped tube is a single part, and the no-load circuit is a single U-shaped tube. And the end deflectors at both ends, so that it can be easily assembled.
According to a ball screw nut according to claim 5, in the ball screw nut according to claim 2 or 3, the U-shaped tube is divided into two in the longitudinal direction, and one is integrated with one of the both end deflectors. The other is integrated with the other of the two end deflectors, and the no-load circuit is composed of these two parts. Therefore, the number of parts can be reduced, facilitating assembly and easy part management. Can be achieved.
According to a ball screw nut according to claim 6, in the ball screw nut according to claim 2 or claim 3, the end deflectors are respectively integrated at both ends of the U-shaped tube. Since it is composed of parts, the number of parts can be reduced, and assembling and parts management can be facilitated.
According to a ball screw nut according to claim 7, in the ball screw nut according to any one of claims 2 to 6, a plurality of the no-load circulation paths are provided, and each of the end deflectors is provided with each of the end deflectors. Since the communication recess corresponding to the no-load circulation path is formed, it is only necessary to install one end deflector at each end of the ball screw nut main body, thereby reducing the number of parts, Assembling and parts management can be facilitated.
According to a ball screw nut according to claim 8, in the ball screw nut according to any one of claims 1 to 7, a no-load circuit is provided on an outer periphery of the ball screw nut body corresponding to the U-shaped tube. Since the groove is provided, the rolling element rolls and circulates between the no-load circuit groove and the U-shaped tube, and the U-shaped tube is moved by the amount of the no-load circuit groove. The height protruding to the outer peripheral side of the ball screw nut main body can be reduced, and thus the size can be reduced.
According to a ball screw mechanism according to claim 9, the ball screw nut according to any one of claims 1 to 8 and the ball screw screwed and disposed on the ball screw nut are configured. Can be downsized.
According to the actuator of the tenth aspect, since the slider is movably disposed using the ball screw mechanism according to the ninth aspect, the size can be reduced. In addition, the size of the slider can be reduced by reducing the size of the ball screw nut. At that time, it is not necessary to reduce the thickness of the slider, so that the necessary strength is sufficiently ensured.

FIG. 2 is a diagram showing a first embodiment of the present invention, and is a perspective view of an actuator, and shows a state in which one side of a side cover, a ball screw nut fixing member, and a half of a slider are removed. It is a figure which shows the 1st Embodiment of this invention and is a perspective view which shows a ball screw mechanism. It is a figure which shows the 1st Embodiment of this invention, and is III-III sectional drawing of FIG. It is a figure which shows the 1st Embodiment of this invention, and is IV-IV sectional drawing of FIG. It is a figure which shows the 1st Embodiment of this invention and is a disassembled perspective view of a ball screw nut. 6A and 6B are views showing the first embodiment of the present invention, in which FIG. 6A is a view of the end deflector as viewed from the side where the connecting groove is opened, and FIG. 6B is a view of VIb− in FIG. FIG. 6C is a sectional view taken along the line VIc-VIc in FIG. 6A, and FIG. 6D is a sectional view taken along the line VId-VId in FIG. It is a figure which shows the 2nd Embodiment of this invention, and is a perspective view which shows a ball screw mechanism. It is a figure which shows the 3rd Embodiment of this invention, and is a perspective view which shows a ball screw mechanism. It is a figure which shows the 4th Embodiment of this invention, and is a cross-sectional view of a ball screw mechanism. It is a figure which shows the 5th Embodiment of this invention, and is a perspective view which shows a ball screw mechanism. It is a figure which shows the 5th Embodiment of this invention, and is XI-XI sectional drawing of FIG. 12A and 12B are views showing a conventional ball screw mechanism, in which FIG. 12A is a perspective view of the ball screw mechanism, and FIG. 12B is a sectional view taken along line XIIb-XIIb of FIG.

Hereinafter, the first embodiment of the present invention will be described with reference to FIGS.
First, the configuration of the actuator 1 according to the first embodiment will be described.
As shown in FIG. 1, the actuator 1 includes a housing 3, a slider 5 installed in the housing 3 so as to be movable in the front-rear direction (a direction from the lower left to the upper right in FIG. 1), and moves the slider 5. The ball screw mechanism 7 and a motor (not shown) that drives the ball screw mechanism 7 are configured.

  The housing 3 includes a base 9 having a substantially U-shaped cross-sectional shape installed on the bottom surface (lower side in FIG. 1), and a width direction of the base 9 on the upper side in FIG. Side cover 11, 11 installed on both sides (the side cover 11 on the lower right side in FIG. 1 is not shown) and the end cover installed at the tip of the base 9 (the lower left end in FIG. 1) 13 and a motor case 15 installed at the rear end of the base 9 (upper right end in FIG. 1). The motor case (not shown) is installed in the motor case 15.

  In the space surrounded by the base 9 and the side covers 11, 11 in the housing 3, the ball screw mechanism 7 is installed. The ball screw mechanism 7 includes a ball screw 17 and a ball screw nut 19. The ball screw 17 is rotatably supported at both ends by a bearing (not shown) housed in the end cover 13 and a bearing 21 housed on the front end side (lower left side in FIG. 1) of the motor case 15. . As shown in FIG. 2, the ball screw 17 has spiral grooves 23a, 23b, 23c, 23d, 23e, and 23f. The ball screw 17 is connected to the output shaft of the motor (not shown) via a coupling (not shown), and is rotated and driven by the motor (not shown). The ball screw nut 19 is installed in a state of being penetrated by the ball screw 17.

  For example, as shown in FIG. 2, the ball screw nut 19 includes, for example, two end deflectors 27 a, 27 b, and 27 c that are installed on each of the ball screw nut body 25 and both ends of the ball screw nut body 25. 27d, and U-shaped tubes 29a and 29b installed between the end deflectors 27a and 27c and the end deflectors 27b and 27d facing each other in the front-rear direction (left and right direction in FIG. 2).

For example, as shown in FIGS. 3 and 4, the ball screw nut body 25 has a through hole 31 extending and formed in the front-rear direction (left and right direction in FIG. 4). Spiral grooves 33a and 33b are formed on the surface.
Further, as shown in FIG. 5, for example, two end deflector mounting recesses 35a, 35b, 35c are provided at both ends of the ball screw nut body 25 in the front-rear direction (the direction from the lower left to the upper right in FIG. 5). , 35d are formed. The end deflectors 27a, 27b, 27c, and 27d are engaged and disposed in the end deflector mounting recesses 35a, 35b, 35c, and 35d.

  End deflector engagement recesses 37 are provided on the front or rear facing surfaces (the surfaces facing the lower left or the upper right in FIG. 5) of the end deflector mounting recesses 35a, 35b, 35c, and 35d. Is formed. (Those formed in the end deflector mounting recesses 35c and 35d are not shown.) Also, the end deflector mounting recesses 35a, 35b, 35c and 35d face forward or rearward (in FIG. 5). An end deflector mounting female screw portion 39 is formed on a surface facing the lower left direction or a surface facing the upper right direction. (Those formed in the end deflector mounting recesses 35b, 35c, 35d are not shown.) Further, one of the side surfaces of the end deflector mounting recesses 35a, 35b, 35c, 35d A drop prevention engagement recess 41 is formed. (Those formed in the end deflector mounting recesses 35b, 35c, 35d are not shown.)

  Further, the front end (left lower end in FIG. 5) of the spiral groove 33a is opened to the end deflector mounting recess 35b, and the rear end (upper right end in FIG. 5) of the spiral groove 33a is the end deflector mounting recess. It is opened at 35d. The front end (left lower end in FIG. 5) of the spiral groove 33b is opened to the end deflector mounting recess 35a, and the rear end (upper right end in FIG. 5) of the spiral groove 33b is the end deflector mounting recess. Opened at 35c.

  As shown in FIGS. 5 and 6, for example, the end deflector 27a is composed of an end deflector body 43 having a substantially arc shape and a U-shaped tube connecting portion 45 protruding and formed on the outer peripheral side. . A communication recess 47 is formed on the ball screw nut body 25 side surface (lower left surface in FIG. 5) of the end deflector 27a. For example, as shown in FIG. 6, the surface of the end deflector 27 a on the side of the ball screw nut body 25 (the surface on the front side in the vertical direction in the middle of FIG. 6A), and the drawing of the communication recess 47. 6 (a), a scooping portion 49a is projected and formed toward the ball screw nut main body 25 side (the front side in the direction perpendicular to the inside of FIG. 6 (a)). In the vicinity of the center in the vertical direction in FIG. 6 (a) and on the right side in FIG. 6 (a), a scooping portion 49b is projected and formed toward the lower side in FIG. 6 (a). These scooping portions 49 a and 49 b are formed with a surface that is continuous with the inner surface of the communication recess 47.

  Further, the outer peripheral side of the U-shaped tube connecting portion 45 protrudes to the ball screw nut body 25 side (left side in FIG. 6D), and the inner side is a U-shaped tube engaging recess 51. Further, the end deflector main body 43 is engaged with one end side (the upper right side in FIG. 6A) and the surface on the ball screw nut main body 25 side (the front surface in the vertical direction in FIG. 6A). The convex part 53 protrudes and is formed. A mounting screw through hole 55 is formed on one end side of the end deflector body 43 (upper right side in FIG. 6A). Further, on the other end side (the lower end side in FIG. 6) of the end deflector main body 43, a drop preventing engagement convex portion 57 is formed.

When the end deflector 27a is installed in the end deflector mounting concave portion 35a, the engaging convex portion 53 is engaged with the end deflector engaging concave portion 37 of the end deflector mounting concave portion 35a. The mating convex portion 57 is engaged with the drop-preventing engagement concave portion 41 of the end deflector mounting concave portion 35a. The end deflector 27a penetrates the mounting screw through hole 55, and the ball screw nut body 25 is fitted with a mounting screw 59 which is screwed into the end deflector mounting female thread portion 39 of the end deflector mounting recess 35a. Fixed to.
The end deflectors 27b, 27c, and 27d have the same configuration as the end deflector 27a.
The constituent elements of the end deflectors 27b, 27c, and 27d are denoted by the same reference numerals as those of the end deflector 27a, and the description thereof is omitted.

For example, as shown in FIG. 5, the U-shaped tube 29a is a member having a substantially U-shaped cross-sectional shape. As shown in FIGS. 2 to 4, the U-shaped tube 29 a is installed on the outer peripheral side of the ball screw nut body 25. The U-shaped tube 29a is fixed to the outer peripheral side of the ball screw nut body 25 by engaging both ends of the U-shaped tube 29a with the U-shaped tube engaging recesses 51 of the end deflectors 27a and 27c.
A convex portion 29a 'is provided at the center in the longitudinal direction of the U-shaped tube 29a. With the U-shaped tube 29a installed between the end deflectors 27a and 27c, the height and end of the convex portion 29a' The U-shaped tube connecting portions 45 and 45 of the deflectors 27a and 27c are configured to have the same height.
The U-shaped tube 29b has the same configuration as the U-shaped tube 29a. Both ends of the U-shaped tube 29b are engaged with the U-shaped tube engaging recesses 51 of the end deflectors 27b and 27d. It is fixed on the outer periphery.
In the U-shaped tube 29b, a convex portion corresponding to the convex portion 29a 'in the U-shaped tube 29a is denoted by reference numeral 29b'.
The U-shaped tubes 29a and 29b are installed at positions facing the outer peripheral side of the ball screw nut body 25 at 180 °.

  A space between the communication recess 47 of the end deflector 27b and the end deflector mounting recess 35b of the ball screw nut body 25; a space between the U-shaped tube 29b and the outer peripheral surface of the ball screw nut body 25; A no-load circuit 60a is formed by a space between the communication recess 47 of the end deflector 27d and the end deflector mounting recess 35d of the ball screw nut body 25. The no-load circuit 60a and the ball screw In a space between the 17 spiral grooves 23a and the spiral groove 33a of the ball screw nut body 25, a plurality of steel balls 61a are rolling and circulating as rolling elements.

  Further, a space between the communication recess 47 of the end deflector 27a and the end deflector mounting recess 35a of the ball screw nut main body 25, and between the U-shaped tube 29a and the outer peripheral surface of the ball screw nut main body 25. A no-load circuit 60b is formed by the space, the space between the communication recess 47 of the end deflector 27c and the end deflector mounting recess 35c of the ball screw nut body 25, and the inside of the no-load circuit 60b. In the space between the spiral groove 23d of the ball screw 17 and the spiral groove 33b of the ball screw nut body 25, a plurality of steel balls 61b are rolling and circulating as rolling elements.

As shown in FIG. 1, the slider 5 is fixed to the ball screw nut 19. The slider 5 is formed with a recess 65 for accommodating a ball screw nut, and the ball screw nut 19 is accommodated in the recess 65 for accommodating the ball screw nut. The ball screw nut 19 is screwed into the slider 5 through a ball screw nut fixing member (not shown) installed on the front end side (lower left side in FIG. 1) of the slider 5 and the ball screw nut fixing member. The slider 5 is fixed by a bolt (not shown).
An opening 67 is provided between the side covers 11, 11, and the upper side of the slider 5 in FIG. 1 protrudes outside the housing 3 through the opening 67.

Further, guide rails 69 and 69 (the guide rail 69 on the lower right side in FIG. 1 is not shown) are installed on both sides of the inner side of the base 9 (the direction from the upper left to the lower right in FIG. 1). The slider 5 is moved in the front-rear direction (the direction from the lower left to the upper right in FIG. 1) by the guide rails 69 and 69 via both ends of the slider 5 in the width direction (the direction from the upper left to the lower right in FIG. 1). )
Further, the guide rails 69, 69 restrict the rotation of the slider 5 and thus the ball screw nut 19 in the circumferential direction of the ball screw 17. When the ball screw 17 is rotated and driven by a motor (not shown). The slider 5 is moved in the front-rear direction (the direction from the lower left to the upper right in FIG. 1).

Next, the operation of the first embodiment will be described.
When the ball screw 17 is rotated and driven by a motor (not shown), the slider 5 is moved in the front-rear direction (the direction from the lower left to the upper right in FIG. 1) together with the ball screw 17.

At that time, a space between the spiral groove 23a of the ball screw 17 and the spiral groove 33a of the ball screw nut body 25, a communication recess 47 of the end deflector 27b, and an end deflector mounting recess 35b of the ball screw nut body 25 are provided. , A space between the U-shaped tube 29b and the outer peripheral surface of the ball screw nut body 25, a communication recess 47 of the end deflector 27d and an end deflector mounting recess 35d of the ball screw nut body 25. A plurality of steel balls 61a roll and circulate in the space between them.
Similarly, the space between the spiral groove 23d of the ball screw 17 and the spiral groove 33b of the ball screw nut body 25, the communication recess 47 of the end deflector 27a, and the end deflector mounting recess of the ball screw nut body 25. A space between the U-shaped tube 29a and the outer peripheral surface of the ball screw nut body 25, a communication recess 47 of the end deflector 27c, and an end deflector mounting recess 35c of the ball screw nut body 25; A plurality of steel balls 61b roll and circulate in the space between the two.

The steel ball 61a is connected to the space between the spiral groove 23a of the ball screw 17 and the spiral groove 33a of the ball screw nut body 25 and the end deflector via the scooping portions 49a and 49b of the end deflector 27b. It is smoothly moved between the communication recess 47b of 27b and the space between the end deflector mounting recess 35b of the ball screw nut body 25.
Further, the steel ball 61a has a space between the connecting recess 47 of the end deflector 27d and the end deflector mounting recess 35d of the ball screw nut body 25 through the scooping portions 49a and 49b of the end deflector 27d. And a space between the spiral groove 23a of the ball screw 17 and the spiral groove 33a of the ball screw nut main body 25.

The steel ball 61b is connected to the space between the spiral groove 23d of the ball screw 17 and the spiral groove 33b of the ball screw nut body 25 and the end deflector via the scooping portions 49a and 49b of the end deflector 27a. It is smoothly moved between the communication recess 47a of 27a and the space between the end deflector mounting recess 35a of the ball screw nut body 25.
Further, the steel ball 61b has a space between the connecting recess 47 of the end deflector 27c and the end deflector mounting recess 35c of the ball screw nut body 25 through the scooping portions 49a and 49b of the end deflector 27c. And the space between the spiral groove 23d of the ball screw 17 and the spiral groove 33b of the ball screw nut body 25 is smoothly moved.

Further, the end deflector 27a is configured such that the drop-off prevention engagement convex portion 57 is engaged with the drop-off prevention engagement concave portion 41 of the end deflector attachment concave portion 35a and penetrates the attachment screw through hole 55. The steel ball 61b is fixed to the ball screw nut body 25 by a mounting screw 59 that is screwed to the end deflector mounting female thread portion 39 of the end deflector mounting recess 35a. Movement from the space between the spiral groove 23d and the spiral groove 33b of the ball screw nut body 25 to the space between the communication recess 47 of the end deflector 27a and the end deflector mounting recess 35a of the ball screw nut body 25 When this is done, the end deflector 27a is separated from the ball screw nut body 25 by being urged by the steel ball 61b. Never would.
Similarly, the end deflectors 27b, 27c, and 27d are not separated from the ball screw nut body 25 by the steel ball 61a or the steel ball 61b.

Next, the effect of the first embodiment will be described.
First, U-shaped tubes 29a and 29b are installed on the outer peripheral side of the ball screw nut main body 25, and a no-load circulation path is provided between the outer peripheral surface of the ball screw nut main body 25 and the U-shaped tubes 29a and 29b and the inner surface. Since 60a and 60b are formed, the diameter of the ball screw nut body 25 can be reduced.
Further, by using the U-shaped pipes 29a and 29b, for example, the ball screw nut body 25 of the unloaded circulation paths 60a and 60b is equal to the thickness of the pipe as compared with the case of using a cylindrical pipe. The amount of protrusion to the outside can be reduced, whereby the ball screw nut 19 and thus the slider 5 and the actuator 1 can be reduced in size.

  In addition, by installing the three parts, that is, the U-shaped pipe 29a and the end deflectors 27a and 27c in the ball screw nut body 25, the no-load circuit 60b can be configured. By installing the three parts, that is, the U-shaped pipe 29b and the end deflectors 27b and 27d on the ball screw nut body 25, the no-load circuit 60a can be configured. Can be assembled easily.

Further, the end deflectors 27a, 27b, 27c, and 27d have a configuration in which the communication concave portion 47 is formed and have a simple configuration without a tubular portion. 60a and 60b can be configured easily.
Further, since the end deflectors 27a, 27b, 27c, 27d are engaged with the end deflector mounting recesses 35a, 35b, 35c, 35d and are fixed by the mounting screws 59, the end deflectors 27a, 27b, 27c, 27d can be easily installed.
Further, since the U-shaped tubes 29a and 29b are installed at positions opposed to 180 °, the size in the left-right direction in FIG. 3 can be particularly reduced.
Further, the size of the ball screw nut 19 can be reduced, so that the slider 5 can be reduced in size. At this time, it is not necessary to reduce the thickness of the slider, and thus the necessary strength can be sufficiently ensured. .
Further, the end deflectors 27a to 27d are screwed in a state where the drop-off preventing engagement convex portions 57 are engaged with the drop-off prevention engagement concave portions 41 of the end deflector mounting concave portions 35a to 35d. It is possible to prevent inadvertent dropping in the direction.

Next, a second embodiment of the present invention will be described with reference to FIG. In the case of the first embodiment, the no-load circuit 60a is composed of three parts, the end deflectors 27b and 27d, and the U-shaped pipe 29b. Similarly, the no-load circuit 60b is the end deflectors 27a and 27c. The U-shaped tube 29a is composed of three parts.
On the other hand, in the case of the second embodiment, the U-shaped tube 29a is bisected in the longitudinal direction to form U-shaped tube elements 29a ₁ and 29a _2, and these U-shaped tube elements 29a ₁ and 29a ₂ are The end deflectors 27a and 27c are integrated with each other so as to be constituted by two parts. Similarly, the U-shaped tube 29b is bisected in the longitudinal direction to form U-shaped tube elements 29b ₁ and 29b _2, and these U-shaped tube elements 29b ₁ and 29b ₂ are integrated with the end deflectors 27b and 27d, respectively. It consists of parts. Further, the convex portion 29a ′ is composed of convex portions 29a ₁ ′ and 29a ₂ ′ formed respectively on the U-shaped tube elements 29a ₁ and 29a ₂ , and the convex portion 29b ′ is similarly formed in the U-shape. The tube elements 29b ₁ and 29b ₂ are formed of convex portions 29b ₁ ′ and 29b ₂ ′ formed respectively.
In FIG. 7, the U-shaped tube element 29a ₁ and the U-shaped tube element 29a ₂ and the U-shaped tube element 29b ₁ and the U-shaped tube element 29b ₂ have the same length, but are divided into different lengths. May be.
Other configurations are the same as those of the first embodiment, and the same reference numerals are given to the same portions in the drawing, and description thereof is omitted.

  In the case of the second embodiment, the same effects as those of the first embodiment can be obtained, and the number of parts for configuring the no-load circulation paths 60a and 60b can be reduced. Assembling and parts management can be facilitated.

Next, a third embodiment of the present invention will be described with reference to FIG. In the case of the first embodiment, the no-load circuit 60a is composed of three parts, the end deflectors 27b and 27d, and the U-shaped pipe 29b. Similarly, the no-load circuit 60b is the end deflectors 27a and 27c. The U-shaped tube 29a is composed of three parts.
On the other hand, in the case of the third embodiment, the end deflectors 27a and 27c and the U-shaped tube 29a are integrated to form a single component. Similarly, the end deflectors 27b and 27d and the U-shaped tube 29b are integrated to form a single component.
Other configurations are the same as those of the first embodiment, and the same reference numerals are given to the same portions in the drawing, and description thereof is omitted.

  In the case of the third embodiment, the same effects as those of the first embodiment can be obtained, and the number of parts for configuring the no-load circulation paths 60a and 60b can be further reduced. Therefore, it is possible to facilitate assembly and facilitate component management.

Next, a fourth embodiment of the present invention will be described with reference to FIG.
In the case of the fourth embodiment, in the configuration of the first embodiment, the no-load circuit grooves 93a and 93b are formed on the outer peripheral surface of the ball screw nut body 25, and the no-load circuit A part of the no-load circulation path 60a is constituted by the circulation path groove 93b and the U-shaped pipe 29b. Similarly, a part of the no-load circulation path 60b is constituted by the no-load circulation path groove 93a and the U-shaped pipe 29a. Is configured.
The other configurations are the same as those of the first embodiment, and the same parts are denoted by the same reference numerals in the drawings, and the description thereof is omitted.

  According to the fourth embodiment, the same effect as that of the first embodiment can be obtained, and the steel ball 61b rolls between the no-load circuit groove 93a and the U-shaped tube 29a. Since the steel ball 61a rolls and circulates between the no-load circulation path groove 93b and the U-shaped tube 29b, the height of the U-shaped tubes 29a and 29b (the size in the vertical direction in FIG. 9). In addition, the protrusion height of the end deflectors 27a, 27b, 27c, 27b to the outer peripheral side of the ball screw nut body 25 (size in the vertical direction in FIG. 9) can be further reduced, and the ball screw nut 19 can be made smaller. Can be

Next, a fifth embodiment of the present invention will be described with reference to FIGS.
The ball screw mechanism 95 according to the fifth embodiment includes a ball screw nut 96. The ball screw nut 96 includes a ball screw nut main body 94, end deflectors 97 a and 97 b installed at both ends of the ball screw nut main body 94, and three U-shapes installed on the outer peripheral side of the ball screw nut 96. It consists of tubes 29a, 29b and 29c. The end deflectors 97a and 97b are formed with first to third communication recesses (not shown). The ball screw nut main body 94 has substantially the same configuration as the ball screw nut main body 25 in the first embodiment described above, and has a through hole 31 and spiral grooves 33a and 33b.
In the U-shaped tube 29c, a convex portion corresponding to the convex portion 29a 'in the U-shaped tube 29a is denoted by reference numeral 29c'.

  That is, the ball screw mechanism 95 has three no-load circulation paths 60a, 60b, and 60c as shown in FIG. The no-load circuit 60 a is a space between the first connecting recess of the end deflector 97 a and the ball screw nut body 94, and a space between the U-shaped pipe 29 b and the outer peripheral surface of the ball screw nut body 94. The space between the first connecting recess of the end deflector 97b and the ball screw nut body 94 is formed. Similarly, the no-load circulation path 60b is formed between the space between the second connecting recess of the end deflector 97a and the ball screw nut body 94, the U-shaped tube 29a, and the outer peripheral surface of the ball screw nut body 94. A space between the second connecting recess of the end deflector 97b and the ball screw nut body 94, and the no-load circuit 60c is used for the third connecting of the end deflector 97a. A space between the concave portion and the ball screw nut main body 94, a space between the U-shaped tube 29c and the outer peripheral surface of the ball screw nut main body 94, a third communication concave portion of the end deflector 97b and the ball screw nut. A space between the main body 94 is formed.

  A plurality of steel balls 61a roll and circulate in the space between the no-load circulation path 60a and the spiral groove 33a of the ball screw nut body 94 and the spiral groove 23f of the ball screw 17. A plurality of steel balls 61b roll and circulate in the space between the unloaded circulation path 60b and the spiral groove 33b of the ball screw nut body 94 and the spiral groove 23d of the ball screw 17. A plurality of steel balls 61c roll and circulate in the space between the load circulation path 60c and the spiral groove 33c of the ball screw nut body 94 and the spiral groove 23b of the ball screw 17.

  In addition, U-shaped pipe connection portions 98a, 98b, and 98c are formed in the end deflectors 97a and 97b, respectively. The U-shaped tube connecting portion 98a is provided with a second communication recess (not shown), and the U-shaped tube connection portion 98b is provided with a first communication recess (not shown). The third connecting recess (not shown) is opened in the character tube connecting portion 98c.

The U-shaped tube connecting portions 98a, 98b, and 98c are formed with U-shaped tube engaging recesses 99, and the U-shaped tubes 29a, 29b, and 29c have both ends at the end deflector 97a or the end deflector 97b. The U-shaped tube engaging recess 99 is engaged and fixed.
The other configurations are the same as those of the first embodiment, and the same parts are denoted by the same reference numerals in the drawings, and the description thereof is omitted.

  According to the fifth embodiment, the same effects as those of the first embodiment can be obtained, and the end deflectors 97a and 97b can be installed at both ends of the ball screw nut 96, and the number of parts can be reduced. Therefore, the assembly can be facilitated and the parts management can be facilitated.

The present invention is not limited to the first to fifth embodiments.
In the case where a part in which an end deflector and a U-shaped tube are integrated as in the second embodiment or the third embodiment is used, or a plurality of communication recesses are formed as in the fifth embodiment. Even when the end deflector is used, it is conceivable to provide a no-load circuit groove in the ball screw nut body as in the fourth embodiment.
Further, even when three no-load circulation paths are provided, it is conceivable to install a pair of end deflectors separately for each no-load circulation path.
Further, there may be a case where four or more no-load circulation paths are provided.
In addition, the size, shape, number, and the like of each component are examples, and various cases are conceivable.

  The present invention relates to, for example, a ball screw nut used for reciprocal movement of a slider, a ball screw mechanism using the ball screw nut, and an actuator using the ball screw mechanism, and in particular, can be miniaturized. For example, it is suitable for an actuator used in an industrial robot.

DESCRIPTION OF SYMBOLS 1 Actuator 7 Ball screw mechanism 17 Ball screw 19 Ball screw nut 27a End deflector 27b End deflector 27c End deflector 27d End deflector 29a U-shaped pipe 29b U-shaped pipe 47 Communication recessed part 61a Steel ball (rolling element)
61b Steel balls (rolling elements)
71 Ball screw mechanism 81 Ball screw mechanism 91 Ball screw mechanism 93a No-load circuit groove 93b No-load circuit groove 95 Ball screw mechanism 96 Ball screw nut 97a End deflector 97b End deflector

Claims (10)

A ball screw nut body;
A U-shaped tube installed on the outer periphery of the ball screw nut body and constituting a part of a no-load circulation path of the rolling element;
A ball screw nut comprising: The ball screw nut according to claim 1,
At both ends of the ball screw nut main body, concave end deflectors having communication concave portions for guiding the rolling elements circulating inside to the U-shaped pipe are installed,
A ball screw nut characterized in that the no-load circuit is constituted by the both end deflectors and the U-shaped pipe. The ball screw nut according to claim 2,
An engagement portion is provided between the end deflector and the ball screw nut body to prevent the end deflector from being detached in the axial direction. In the ball screw nut according to claim 2 or 3,
The ball screw nut is characterized in that the U-shaped pipe is a single part, and the no-load circuit is composed of a single U-shaped pipe and three end deflectors. In the ball screw nut according to claim 2 or 3,
The U-shaped pipe is divided into two in the longitudinal direction, one is integrated with one of the two end deflectors, the other is integrated with the other of the two end deflectors, and the no-load circuit is composed of these two parts. Ball screw nut characterized by being made. In the ball screw nut according to claim 2 or 3,
A ball screw nut, wherein the end deflectors are respectively integrated at both ends of the U-shaped tube, and the no-load circuit is composed of one part. In the ball screw nut according to any one of claims 2 to 6,
A ball screw nut, wherein a plurality of the no-load circulation paths are provided, and the end deflector is formed with a communication recess corresponding to each of the no-load circulation paths. In the ball screw nut according to any one of claims 1 to 7,
A ball screw nut characterized in that a groove for a no-load circulation path is provided on an outer periphery of the ball screw nut body corresponding to the U-shaped tube.   A ball screw mechanism comprising: the ball screw nut according to any one of claims 1 to 8; and a ball screw screwed and disposed on the ball screw nut.   An actuator, wherein the slider is movably arranged using the ball screw mechanism according to claim 9.

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