JP2008309331A - Ball screw mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ball screw mechanism superior in installation performance, and reducing incorporation time. <P>SOLUTION: A deflector 4 is approached to an installation hole 2b of a nut 2 from the outer peripheral side of the nut 2, and a cylindrical part 4b is fitted in the installation hole 2b, and a flange part 4c is butted against and fitted in a positioning groove 2c. Thus, since a phase of a circulating groove 4a is determined with a body 4b as the axis, positioning with a rolling travel passage is accurately performed, and noise and vibration of a ball 3 is restrained. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is applied to a deflector-type ball screw mechanism suitable for mechanical devices, automobile parts (including motorcycles), and marine applications. Is.

  In recent years, labor saving of vehicles and the like has progressed, and for example, a system has been developed in which a transmission, a parking brake, and the like of an automobile are performed not by hand but by the power of an electric motor. An electric actuator used for such an application may use a ball screw mechanism in order to convert the rotational motion transmitted from the electric motor into the axial motion with high efficiency.

As one form of the ball screw mechanism, a deflector type ball screw mechanism as shown in Patent Document 1 is known. In the deflector-type ball screw mechanism disclosed in Patent Document 1, a deflector fixed to a nut includes a substantially rectangular main body and a pair of flange portions provided to protrude outwardly at both ends in the short direction of the main body portion. Is provided.
Japanese Patent No. 3736912

  However, when the deflector disclosed in Patent Document 1 is assembled in the nut mounting hole, the deflector has a different longitudinal and short gaps, so the posture at the time of incorporation is not stable, and the assembling time is long for adjustment. There was a problem of this.

  The present invention has been made in view of the problems of the prior art, and an object of the present invention is to provide a ball screw mechanism that is excellent in assembling property and can reduce the assembling time.

The ball screw mechanism of the present invention is
A screw shaft having a male screw groove formed on the outer peripheral surface;
A nut disposed so as to surround the screw shaft and having an internal thread formed on an inner peripheral surface thereof;
A plurality of balls arranged to freely roll along a rolling path formed between opposing screw grooves;
A deflector attached to the mounting hole of the nut,
The deflector has a cylindrical main body formed with a circulation groove connected to one end and the other end of the rolling path, extends from the outer periphery of the main body to both sides in the circumferential direction of the nut, and is attached to the nut. And a flange portion formed so as not to protrude from the outer diameter of the nut.

  According to the present invention, the deflector extends from the outer periphery of the main body to both sides in the circumferential direction of the nut, and the cylindrical main body is formed with a circulation groove connected to one end and the other end of the rolling path. And a flange portion formed so as not to protrude from the outer diameter of the nut when attached to the nut, the clearance with the mounting hole of the nut becomes uniform, and the flange portion is formed on the outer periphery of the nut. By fitting in the linear groove, the function of determining the phase of the circulation groove around the cylindrical main body can be obtained.

  The cylindrical main body of the deflector is fitted in the mounting hole of the nut, and the flange portion of the deflector is fitted in a linear groove formed on the outer periphery of the nut, and the cylindrical main body It is preferable to determine the phase of the circulation groove around the axis.

  The nut is provided with a circular attachment hole for fitting the cylindrical main body to attach the deflector and a positioning groove for fitting the flange portion, and at least a part of the positioning groove When the flange portion is deformed by caulking, it is preferable that a dovetail groove that comes into contact with the side wall is provided.

  The deflector is preferably fitted into the mounting hole of the nut and the positioning groove, and a portion deformed by caulking the nut outer diameter surface side of the flange portion is preferably abutted and fixed to the dovetail groove.

  The flange portion is preferably formed so as to be positioned on the bottom side of the dovetail groove with respect to the portion of the dovetail groove closest to the outer surface of the nut in a state where the deflector is attached to the nut.

  A concave portion or a notch is formed in the flange portion, and at least a part of the flange portion is plastically deformed so as to spread the concave portion or the notch using a tool engaged with the concave portion or the notch. It is preferable to be biased toward the straight groove or the side wall of the positioning groove.

  It is preferable that the concave portion has a tapered surface inclined so as to be separated from the side wall toward the bottom side of the linear groove or the positioning groove in a state where the deflector is attached to the nut.

  The notch is preferably a slit extending from the tip of the flange portion toward the main body.

  It is preferable that a clearance groove is formed on a side near the axis of the nut in a state where the deflector is attached to the nut at a boundary between the main body of the deflector and the flange portion.

  The deflector is preferably formed by metal powder injection molding or press sintering, but may be formed by machining, precision casting, or die casting.

  Next, embodiments of the present invention will be described with reference to the drawings. 1 and 2 are perspective views of the ball screw mechanism according to the present embodiment, FIG. 3 is a top view of the deflector according to the first embodiment, and FIG. 4 shows the configuration of FIG. It is the figure which cut | disconnected by the -IV line and looked at the arrow direction. 5 shows a state in which the deflector is assembled to the nut, FIG. 6 is an enlarged view of the outer periphery of the nut 2 in FIG. 5 as viewed in the direction of arrow VI, and FIG. 7 is a view in which the deflector is further assembled. However, the end face of the flange portion of the deflector is shown in a dark color for easy understanding.

  In FIG. 1, a male screw groove 1a is formed on the outer peripheral surface of a screw shaft 1 connected to a driven member and supported so as not to rotate but to move only in the axial direction. A cylindrical nut 2 supported so as to be rotatable only with respect to a housing (not shown) is disposed so as to surround the screw shaft 1 and has a female screw groove 2a formed on an inner peripheral surface thereof. A plurality of balls 3 are arranged so as to be able to roll in a spiral rolling path formed between the opposing screw grooves.

  As shown in FIG. 5, on the outer periphery of the nut 2, a cylindrical mounting hole 2b penetrating in the radial direction, and a positioning extending linearly opposite to the mounting hole 2b in both circumferential directions of the nut 2. A groove 2c is formed. At least a part of the positioning groove 2c (particularly at a position corresponding to a caulking C described later) is provided with a so-called dovetail groove in which the width of the side wall becomes wider toward the bottom as shown in FIG.

  As shown in FIGS. 3 and 4, the deflector 4 mounted in the mounting hole 2 b includes a cylindrical main body 4 b formed with a circulation groove 4 a connected to one end and the other end of the rolling path, and an outer periphery of the main body 4 b. And a flange portion 4c having a rectangular cross-sectional plate shape that extends symmetrically in the circumferential direction of the nut 2 and that does not protrude from the outer diameter of the nut 2 when attached to the nut 2. The outer surface of the main body 4b and the outer surface of the flange portion 4c connected thereto are preferably part of a cylindrical surface having the same diameter as the outer peripheral surface of the nut 2. In such a case, the flange portion 4c becomes thinner toward the tip. Such a deflector 4 can be formed by metal powder injection molding or press sintering.

  The operation of the present embodiment will be described. When the nut 2 is rotationally driven by an electric motor (not shown), the rolling path rolls and from one end of the rolling path to the other end via the circulation path 4a of the deflector 4. The rotating ball 3 efficiently converts the rotational motion into the axial motion of the screw shaft 1, and a driven member (not shown) connected thereto can be moved in the axial direction.

  An assembly mode of the deflector 4 of the ball screw mechanism according to the present embodiment will be described. 5, the deflector 4 having the shape shown in FIGS. 3 and 4 is brought close to the mounting hole 2b of the nut 2 from the outer peripheral side of the nut 2, the cylindrical portion 4b is fitted into the mounting hole 2b, and the positioning groove 2c is flanged. The part 4c is abutted and fitted. Thereby, since the phase of the circulation groove 4a and the fitting depth of the cylindrical portion 4b can be determined with the main body 4b as an axis, positioning with the rolling path can be performed with high accuracy, and noise and vibration of the ball 3 are suppressed. it can.

  After the flange portion 4c is abutted against the positioning groove 2c, a bifurcated tip (having an outer tapered surface) J1 of the crimping tool J shown in FIG. 5 is brought into contact with the upper surface of the flange portion 4c of the deflector 4, and By applying an impact force, both sides of the upper surface of the flange portion 4c are crimped (C in FIG. 7) to cause plastic deformation, and the side wall of the flange portion 4c is fixed to the positioning groove 2c. Thereby, the side surface of the flange portion 4c is pressed against the side wall of the positioning groove 2c, and the deflector 4 is prevented from coming out of the mounting hole 2b.

  According to the present embodiment, by forming the body of the deflector 4 in a cylindrical shape, the mounting hole 2b of the nut 2 can be easily processed, and when further fixed, the flange portion 4b is simultaneously crimped at a plurality of locations. Since the fixing can be performed, the caulking fixing can be completed in a short time.

  FIG. 8 is a perspective view of the deflector 14 according to the second embodiment, and FIG. 9 is a view similar to FIG. 7 showing the deflector 14 attached to the nut 2. The end face is shown in dark color.

  Similar to the above-described embodiment, the deflector 14 according to the present embodiment includes a cylindrical main body 14b in which a circulation groove 14a connected to one end and the other end of the rolling path is formed on the lower surface, and an outer periphery of the main body 14b. And a thin plate-like flange portion 14c that extends symmetrically in the circumferential direction of the nut 2. The flange portion 14c is provided at a position one step lower than the upper surface of the main body 14b.

  Therefore, as shown in FIG. 9, when the deflector 14 is attached to the nut 2, the upper surface of the flange portion 14 c is a distance Δ than the portion X of the positioning groove 2 c (the dovetail groove) closest to the outer surface of the nut 2. It is formed close to the bottom side of the positioning groove 2c. Thereby, even if the amount of plastic deformation due to the caulking C is small, the flange portion 14c is not easily pulled out from the dovetail groove, and the ease of manufacture is improved.

  FIG. 10 is a perspective view of the deflector 24 according to the third embodiment, and FIG. 11 is a view showing the configuration of FIG. 10 assembled to the nut 2 in a state cut along a plane passing through the XI-XI line. The cut surface is indicated by hatching.

  The deflector 24 according to the present embodiment has the same shape as that of the first embodiment, except that a pair of thin and deep recesses 24d are formed on the upper surface of the flange portion 24c. When the deflector 24 is attached to the nut 2, the concave portion 24 d has a tapered surface 24 e that is inclined toward the bottom side of the positioning groove 2 c as a surface close to the side wall of the positioning groove (ant groove) 2 c. Have. A surface 24f facing the tapered surface 24e in the recess 24d is a surface parallel to the axis of the main body 24b.

  At the time of assembly of the present embodiment, as shown in FIG. 11, the forked tip J1 of the caulking tool J is engaged with the concave portion 24d on the upper surface of the flange portion 24c, and further an impact force is applied, whereby the tapered surface 24e. Is pushed outward (that is, the recess 24d is expanded), and thereby the side surface of the flange portion 24c is pressed against the side wall of the positioning groove 2c as indicated by an arrow. Thus, the flange portion 24c is fixed to the positioning groove 2c, and the deflector 24 is prevented from coming out of the mounting hole 2b (see FIG. 5).

  FIG. 12 is a perspective view of a deflector 34 according to the fourth embodiment, and FIG. 13 is a diagram showing the configuration of FIG. 12 assembled to the nut 2 in a state cut along a plane passing through the XIII-XIII line. The cut surface is indicated by hatching.

  The deflector 34 according to this embodiment has the same shape as that of the first embodiment, except that a slit 34d that is a notch is formed from the center of the tip of the flange portion 34c toward the main body 34b. . A cylindrical portion 34e penetrating vertically is formed at the inner end of the slit 34d. The cylindrical part 34e functions to relieve stress during plastic deformation so that the flange part 34c does not break.

  At the time of assembly of the present embodiment, as shown in FIG. 13, the tip of a thin wedge-shaped caulking tool J is inserted into the slit 34d of the flange portion 34c, and the slit 34d is further spread by applying an impact force. Thus, the side surface of the flange portion 34c is pressed against the side wall of the positioning groove 2c. Thus, the flange portion 34c is fixed to the positioning groove 2c, and the deflector 34 is prevented from coming out of the mounting hole 2b (see FIG. 5).

  FIG. 14 is a bottom view of the deflector 44 according to the fifth embodiment, and FIG. 15 is a view of the configuration of FIG. 14 cut along the XV-XV line and viewed in the arrow direction.

  The deflector 44 according to the present embodiment has the same shape as that of the first embodiment, but with the root of the flange portion 44c (the boundary with the main body 44b and the flange portion 44c attached to the nut 2). On the side close to the axis of the nut 2, a relief groove 44g having a semicircular cross section extending along the outer diameter of the main body 44b is formed. The escape groove 44g is provided in order to avoid interference with the edge corner of the mounting hole 2b (see FIG. 5) of the nut 2.

  The present invention has been described above with reference to the embodiments. However, the present invention should not be construed as being limited to the above-described embodiments, and can be modified or improved as appropriate.

It is a perspective view of the ball screw mechanism which is this Embodiment. It is a perspective view of the ball screw mechanism which is this Embodiment. It is a top view of the deflector concerning a 1st embodiment. It is the figure which cut | disconnected the structure of FIG. 3 by the IV-IV line and looked at the arrow direction. It is a figure which shows the state which integrated the deflector in the nut. It is the enlarged view which looked at the outer periphery of the nut 2 of FIG. 5 in the arrow VI direction. It is the figure of the positioning groove | channel seen in the state which assembled | attached the deflector. It is a perspective view of the deflector 14 concerning 2nd Embodiment. FIG. 8 is a view similar to FIG. 7 showing the deflector 14 attached to the nut 2. It is a perspective view of the deflector 24 concerning 3rd Embodiment. It is a figure which shows the structure of FIG. 10 assembled | attached to the nut 2 in the state cut | disconnected in the surface which passes along a XI-XI line. It is a perspective view of the deflector 34 concerning a 4th embodiment. FIG. 13 is a diagram showing the configuration of FIG. 12 assembled to the nut 2 in a state cut along a plane passing through the XIII-XIII line. It is a bottom view of the deflector 44 concerning a 5th embodiment. It is the figure which cut | disconnected the structure of FIG. 14 by the XV-XV line | wire and looked at the arrow direction.

Explanation of symbols

1 Screw shaft 1a Male thread groove 2 Nut 2a Female thread groove 2b Mounting hole 2c Positioning groove 3 Ball 4, 14, 14, 34, 44 Deflector 4a, 14a, 14a, 34a, 44a Circulation groove 4b, 14b, 14b, 34b, 44b Main body 4c, 14c, 14c, 34c, 44c Flange

Claims (10)

A screw shaft having a male screw groove formed on the outer peripheral surface;
A nut disposed so as to surround the screw shaft and having an internal thread formed on an inner peripheral surface thereof;
A plurality of balls arranged to freely roll along a rolling path formed between opposing screw grooves;
A deflector attached to the mounting hole of the nut,
The deflector has a cylindrical main body formed with a circulation groove connected to one end and the other end of the rolling path, extends from the outer periphery of the main body to both sides in the circumferential direction of the nut, and is attached to the nut. A ball screw mechanism comprising: a flange portion formed so as not to protrude from the outer diameter of the nut.   The cylindrical main body of the deflector is fitted in the mounting hole of the nut, and the flange portion of the deflector is fitted in a linear groove formed on the outer periphery of the nut, and the cylindrical main body The ball screw mechanism according to claim 1, wherein the phase of the circulation groove with the axis as an axis is determined.   The nut is provided with a circular attachment hole for fitting the cylindrical main body to attach the deflector and a positioning groove for fitting the flange portion, and at least a part of the positioning groove 3. A ball screw mechanism according to claim 1 or 2, wherein a dovetail groove is provided in contact with the side wall when the flange portion is deformed by caulking.   The deflector is fitted in the mounting hole of the nut and the positioning groove, and a portion deformed by caulking the nut outer diameter surface side of the flange portion is in contact with and fixed to the dovetail groove. The ball screw mechanism according to claim 3.   The flange portion is formed so as to be positioned on the bottom side of the dovetail groove with respect to the portion of the dovetail groove closest to the outer surface of the nut in a state where the deflector is attached to the nut. The ball screw mechanism according to claim 3 or 4.   A concave portion or a notch is formed in the flange portion, and at least a part of the flange portion is plastically deformed so as to spread the concave portion or the notch using a tool engaged with the concave portion or the notch. 6. The ball screw mechanism according to claim 2, wherein the ball screw mechanism is biased toward a side wall of the linear groove or the positioning groove.   The concave portion has a tapered surface inclined so as to be separated from a side wall thereof toward the bottom side of the linear groove or the positioning groove in a state where the deflector is attached to the nut. 6. A ball screw mechanism according to 6.   The ball screw mechanism according to claim 6, wherein the notch is a slit extending from a tip end of the flange portion toward the main body.   2. A clearance groove is formed at a boundary between the main body of the deflector and the flange portion on a side close to an axis of the nut in a state where the deflector is attached to the nut. The ball screw mechanism according to claim 8.   The ball screw mechanism according to claim 1, wherein the deflector is formed by metal powder injection molding or press sintering.