JP4576982B2 - Ball screw device - Google Patents

Description

  The present invention relates to a ball screw device, and more particularly to a ball screw device that can be used for a general industrial machine and a power operating mechanism of a transmission for a vehicle.

  As a driving method of a driven body by a ball screw device, a driving system that drives a driven body by rotating a screw shaft and moving a nut screwed to the screw shaft in the screw shaft direction is widely used. In this configuration, the linear motion of the nut is generally used as it is as the linear motion of the driven body. However, the linear motion of the nut is once converted into the swing motion of the arm member, and the swing motion of the arm member is converted. A driving system is also used in which the driven body is driven by converting the rotation into a rotational motion again (see Patent Document 1).

  FIG. 5 to FIG. 7 are diagrams for explaining a transmission electric drive device (hereinafter referred to as a drive device) 100 for operating a vehicle transmission using the above-described ball screw device with a motor as power. FIG. FIG. 6 is a diagram illustrating an arrangement of the device 100, FIG. 6 is an example of a shift pattern of an operation lever of the vehicle transmission device, and FIG. 7 is a cross-sectional view taken along line AA in FIG.

  First, an outline of the overall configuration will be described. As shown in FIG. 5, the drive device 100 is installed on the case 103 of the vehicle transmission, the operation lever of the vehicle transmission is connected to the drive pin denoted by reference numeral 108 in FIG. It is configured to move according to the shift pattern shown in FIG. 6 and to switch the gear of the vehicle transmission.

  The driving device 100 includes a main housing 104 and a sub housing 105 (see FIG. 5). In FIG. 7, a switching shaft 107 is coaxially disposed inside the shift sleeve 112 inside the main housing 104, and the switching shaft 107 is supported so as to be rotatable about the axial direction and the axis. The switching shaft 107 is provided with a drive pin 108 and protrudes outside the main housing 104.

  A male serration 111 is formed on the right side of the switching shaft 107 in FIG. 7, and is coupled to one end of the shift sleeve 112 via the female serration 113 of the shift sleeve 112. The rotation of the shift sleeve 112 is switched via the serration coupling described above. It is transmitted to the shaft 107.

  In addition, an arc-shaped rack 116 concentric with the switching shaft 107 is formed on the right side of the switching shaft 107 in FIG. 7, and is driven by a motor 109 (see FIG. 5) in an opening 119 formed in the shift sleeve 112. The switching shaft 107 moves to the left and right in the axial direction by the rotation of the pinion 117 that meshes with the rack 116.

  The shift sleeve 112 is provided with two swing arms 122 on the left and right in the vicinity of the opening 119 where the rack 116 and the pinion 117 mesh with each other. A nut 128 is swingably attached via a pin 129. The holding hole 130 of the swing arm 122 that holds the pin 129 is formed as an elongated hole for the reason described later.

  The nut 128 is screwed into a ball screw shaft 124 driven by a motor 110 (see FIG. 5). The rotation of the ball screw shaft 124 causes the nut 128 to move in the axial direction of the ball screw shaft 124 (in FIG. 7, the direction perpendicular to the paper surface). ) And the shift sleeve 112 arranged coaxially with the switching shaft 107 is swung around its axis via the swing arm 122.

  With the above configuration, when the motor 109 (see FIG. 5) is driven, the switching shaft 107 moves in the axial direction via the pinion 117 and the rack 116, and the drive pin 108 moves in the select direction (the horizontal direction passing through the neutral position N in FIG. 6). ), The shift lever of the vehicle transmission device is moved to the gear switching step selection position, and the gear switching step is selected by the shift lever of the vehicle transmission device connected to the drive pin 108.

  Next, when the motor 110 (see FIG. 5) is driven, the swing arm 122 swings around its axis via the ball screw shaft 124, the nut 128, and the swing arm 122, and is connected to the drive pin 108. The shift lever of the vehicle transmission is set to the meshing position with the gear of the previously selected gear switching stage.

In the configuration described above, the nut 128 moves in the axial direction of the ball screw shaft 124 and causes the shift sleeve 112 to swing around its axis (same as the axis of the switching shaft 107) via the swing arm 122. Since the distance between the nut axis and the shift sleeve axis varies, the holding hole 130 provided in the swing arm 122 that holds the nut mounting pin 129 can cope with the above-described variation in the distance. As shown in FIG. 7, the elongated holes are formed in the vertical direction.
JP 2002-317871 A.

  It is not always desirable in terms of the structure to handle a large load when the variation of the gap between the nut axis and the shift sleeve axis as described above is solved by the elongated hole provided in the shift sleeve. Thus, a configuration as described below is proposed, but there is a disadvantage in that the operating point where the nut acts on the oscillating arm is deviated and the life of the ball screw device is shortened. Hereinafter, the configuration and problems to be solved will be described.

  FIG. 8 and FIG. 9 are diagrams for explaining a mechanism portion (hereinafter referred to as a drive mechanism) of the swing arm and the ball screw of the proposed transmission electric drive device.

  8A is a front view showing a part of the drive mechanism in section, and FIG. 8B is a sectional view taken along line AA in FIG. 8A. 8A and 8B, a ball screw shaft 203 of a ball screw device 201 is rotatably supported by a ball bearing 202 held by a housing 200, and one end of the ball screw shaft 203 is connected to a reduction gear device 204. Via the motor 205. When the ball screw shaft 203 is rotated by the rotation of the motor 205, the nut 210 screwed with the ball screw shaft 203 moves in the axial direction. The ball screw device 201 itself is not different from the conventional ball screw device.

  The nut 210 has grooves (slots) 210a and 210b provided with guides 210c and 210d at outer edges on the left and right sides of the ball screw shaft 203 to be screwed, respectively. The substantially disc-shaped tip portion 220a of the moving arm 220 fits loosely along the guide 210c, and the substantially disc-shaped tip portion 221a of the swing arm 221 that is a swing arm to be described later is guided in the groove 210b. It fits loosely along 210d.

  As described above, the swing arms 220 and 221 are formed at the substantially disc-shaped tip portions 220a and 221a that fit into the grooves 210a and 210b of the nut 210 as described above, and the other end portion is driven. The shaft is fixedly coupled to a shift sleeve 230 that is a shaft. Even if the swing arms 220 and 221 swing, the shaft center of the shift sleeve 230 that is a driven shaft does not move, but rotates at that position.

  The operation of the drive mechanism described above will be described. Since the relationship between the swing arm 220 and the groove 210a of the nut 210 and the relationship between the swing arm 221 and the groove 210b of the nut 210 are the same, in the following description, the relationship between the swing arm 220 and the groove 210a of the nut 210 will be described. Only explained.

  FIG. 9 is a diagram for explaining the operation of the drive mechanism. FIG. 9A shows a neutral position of the swing arm 220 of the drive mechanism, that is, the central axis of the swing arm 220 with respect to the axis of the ball screw shaft 203. Shows a state where is in a vertical position.

  The contact point between the tip 220a of the swing arm 220 and the guide 210c of the groove 210a of the nut 210 is at P0, which is on a plane including the axis of the ball screw shaft 203, and is exceptionally different from the ball screw shaft 203. The reaction force of does not work.

  When the nut 210 moves to the right side by the rotation of the ball screw shaft 203 from the state shown in FIG. 9A, the state shown in FIG. The tip 220a of the swing arm 220 is tilted inside the groove 210a, but the other end 220e of the swing arm 220 is fixed to the shift sleeve 230 whose axis does not move. As a result, the swing arm 220 is moved to the shift sleeve 230 side (the upper side in FIG. 9B), and the contact point between the tip 220a of the swing arm 220 and the guide 210c of the groove 210a of the nut 210 is P1. Move to. That is, the contact point moves above the axis of the ball screw shaft 203, and a deviation d occurs at the point of action where the nut 210 acts on the swing arm 220.

  Due to this deviation, as shown in FIG. 9C, a reaction force moment M (M = F × d) obtained by multiplying the axial force F acting on the contact point by the deviation d acts on the nut 210. As a result, a uniform axial force does not act on the ball loaded in the ball screw, and a large surface pressure is partially applied to the ball screw shaft or the ball rolling surface of the nut. The generation of a large surface pressure causes inconvenience that the rolling fatigue of the ball screw is promoted and the life of the ball screw device is shortened.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a ball screw device that solves the above-mentioned disadvantages and prevents the occurrence of deviation of the operating point of the swing arm and can maintain the long life of the ball screw device. is there.

The present invention solves the above-mentioned problems, and the invention of claim 1 circulates and moves through a screw shaft, a nut screwed to the screw shaft, and a ball circulation path formed between the screw shaft and the nut. A ball screw mechanism composed of a plurality of balls, a swingable arm that connects a swingable driven shaft and the nut, and a swingable arm that can be expanded and contracted in the axial direction. The first member is disposed on both sides of the nut and includes only a first member that is rotatably attached to the nut and a second member that is fixed to a swingable driven shaft. The second member and the second member can be expanded and contracted in the arm axis direction, and are prohibited from moving in the direction intersecting the arm axis direction. The first member is connected to the nut. The end is attached to the nut so as to be rotatable around a predetermined swing center. It is, the predetermined swing center includes the axis of the screw shaft, a ball screw device wherein there and the on a plane parallel to the axis of the driven shaft.

  Further, the swing arm includes a coupling member having a substantially disc-shaped end on the side connected to the nut, and the nut includes a recess that fits into the coupling member of the swing arm. .

  Further, the swing arm may be provided with a circular coupling hole at an end portion on a connection side with the nut, and the nut may be provided with a protruding portion that fits into the circular coupling hole of the swing arm.

  The swing arm includes a circular coupling hole at an end of the connection side with the nut, and the nut includes a hole to which a pin that fits into the circular coupling hole of the swing arm is fixed. The moving arm and the nut may be coupled by the pin.

In the ball screw device according to the present invention, the swing arm is disposed on both sides of the nut, the first member is rotatably attached to the nut, and the second member is fixed to the swingable driven shaft. becomes the only two members from the member, wherein the first member and the second member, the arm axis telescopically, in the direction intersecting the arm axis direction is coupled is prohibited movement, The end of the first member on the side connected to the nut is rotatably attached to the nut around a predetermined swing center, and the swing center is the axis of the screw shaft. In addition, it is configured to be on a plane parallel to the axis of the driven shaft, so that even if the swing arm is inclined, no reaction force moment is generated in the nut, and the life of the ball screw mechanism Can be lengthened.

  Embodiments of the present invention will be described below. FIG. 1 and FIG. 2 are views for explaining a drive device comprising a swing arm and a ball screw mechanism according to an embodiment of the present invention, and have been described with reference to FIGS. 8 (a) and 8 (b). The drive mechanism is improved.

  FIG. 1A is a front view showing a cross section of a part of a driving device 10 composed of a swing arm and a ball screw mechanism, and FIG. 1B is a cross-sectional view taken along line BB in FIG. It is sectional drawing which followed the line.

  1A and 1B, a ball screw shaft 12 of a ball screw device 11 is rotatably supported by ball bearings 14 and 15 held by a housing 19, and one end of the ball screw shaft 12 is a reduction gear. It is connected to a motor 18 via a mechanism 17. When the ball screw shaft 12 rotates through the reduction gear mechanism 17 by the rotation of the motor 18, the nut 13 screwed to the ball screw shaft 12 moves in the axial direction. The ball screw device 11 itself is the same as a conventional ball screw device.

  The nut 13 is formed with recesses (slots) 13a and 13b having protrusions 13c and 13d on the outer edges on the left and right, respectively, as viewed from the ball screw shaft 12 to be screwed. An arcuate receiving portion 13p is provided in which the substantially disc-shaped tip portion 21a of the moving arm 21 is fitted loosely and rotatably. Similarly, the concave portion 13b is provided with an arc-shaped receiving portion 13q that fits in a rotatable manner without loosening a substantially disc-shaped tip portion 22a of a swing arm 22 described later.

  That is, the substantially disc-shaped tip portion 21a of the swing arm 21 and the arc-shaped receiving portions 13p and 13q are in a freely swingable contact with an arc surface, and the central axis of the contact arc surface is the ball screw shaft 12. It is located on the axis. In other words, the swing center M of the swing arm 21 is on a plane including the axis of the ball screw shaft 12.

  The swing arm 21 is composed of a first member and a second member. One end of the first member 21A is fitted into a recess 13c provided with the arc-shaped receiving portion 13p of the nut 13 described above. A substantially disc-shaped tip portion 21a is provided, and the other end portion is constituted by a second member 21B (to be described later) and a connecting member (for example, a rod-like body) 21b that is slidable in the axial direction.

  The second member 21B is fixedly coupled to the driven shaft 30 whose one end is swingable, and the other end is slidably coupled to the connecting member 21b of the first member 21A described above. It is comprised by the connection member (for example, hollow body) 21c.

  The sliding connecting portion 21C between the connecting member 21b of the first member 21A and the connecting member 21c of the second member 21B is a connecting portion having a structure that is slidable in the axial direction and does not rotate about the axis. Any structure may be used as long as an inlay joint or the like can be used.

  FIG. 1C is a cross-sectional view showing an example of the configuration of the connecting portion 21C, and is a cross-sectional view taken along the line CC of FIG. The first member 21A and the second member 21B formed in a rectangular cross section are slidable in the axial direction and connected without rotating around the axis.

  The swing arm 22 is also composed of a first member 22A and a second member 22B. Since the configuration is exactly the same as that of the swing arm 21, the description thereof will be omitted. However, the first member 22A of the swing arm 22 is fitted into the recess 13d provided with the arc-shaped receiving portion 13q of the nut 13. The second member 22 </ b> B is fixedly coupled to the driven shaft 30.

  The driven shaft 30 is, for example, a member corresponding to the shift sleeve 112 in FIG. 7 or the shift sleeve 230 in FIG. 8. When the swing arms 21 and 22 swing, the axis of the driven shaft 30 is It is configured not to move but to rotate at that position. The axis of the driven shaft 30 is on a plane parallel to the axis of the ball screw shaft 12, and the axial direction of the driven shaft 30 intersects the axis direction of the ball screw shaft 12 at a right angle.

  The operation of the drive device will be described. Since the relationship between the swing arm 21 and the recess 13c of the nut 13 and the relationship between the swing arm 22 and the recess 13d of the nut 13 are the same, in the following description, the relationship between the swing arm 21 and the recess 13c of the nut 13 is described. Only explained.

  FIG. 2 is a view for explaining the operation of the drive device. FIG. 2A shows the swing arm 21 of the drive device in the neutral position, that is, the central axis of the swing arm 21 with respect to the axis of the ball screw shaft 12. Shows a state where is in a vertical position.

  The contact point between the tip 21a of the swing arm 21 and the arc-shaped receiving part 13p of the recess 13c of the nut 13 is at P, and the contact point P is on a plane including the axis of the ball screw shaft 12, and the ball No special reaction force acts on the screw shaft 12.

  When the nut 13 moves to the right side by the rotation of the ball screw shaft 12 from the state shown in FIG. 2A, the state shown in FIG. The tip 21 a of the swing arm 21 is inclined around the swing center M in the recess 13 c provided with the arc-shaped receiving portion 13 p of the nut 13. At this time, since the second member 22B, which is the other end of the swing arm 21, is fixed to the driven shaft 30 whose axis does not move, the tilt of the swing arm 21 is slid on the swing arm 21. The distance between the first member 21A and the second member 21B is adjusted in the moving connecting portion 21C, and the contact point P and the swing center M between the tip 21a of the swing arm 21 and the recess 13c of the nut do not move.

  With this configuration, even if the swing arm 21 is tilted to the right or left, the swing center of the swing arm 21 always includes the axis of the ball screw shaft 12 and is a plane parallel to the center line of the driven shaft 30. Therefore, the acting force generated in the nut 13 passes through the center of the nut ball circulation path, and no reaction force moment is generated in the nut 13.

  FIGS. 3A and 3B are diagrams for explaining a first modified example of the connection portion between the swing arm and the ball screw. FIG. 3A is a front view thereof, and FIG. 3B is a cross-sectional view thereof. The same members as those in the embodiment described above with reference to FIGS. 1 and 2 are denoted by the same reference numerals.

  3 (a) and 3 (b), the nut 13 is provided with cylindrical projections 13f and 13g at the centers of the two left and right plane portions 13r and 13s of the ball screw shaft 12 to be screwed together. The axial centers of the protrusions 13f and 13g are orthogonal to the axial center of the ball screw shaft 12 and are located on a plane including the axial center of the ball screw shaft 12.

  A circular hole 21f that fits into the columnar protrusion 13f of the nut 13 is formed at the tip 21a of the swing arm 21, and the column shape of the nut 13 is similarly formed at the tip 22a of the swing arm 22. A circular hole 22f that fits into the projection 13g is formed, and the tip portions 21a and 22a of the swing arm are rotatably mounted around the columnar projections 13f and 13g. The swing center M of the swing arm is It is on a plane that includes the axis of the ball screw shaft 12 and is parallel to the center line of the driven shaft 30.

  Even with this configuration, even if the swing arm 21 tilts to the right or left, the swing center M of the swing arm 21 always includes the axis of the ball screw shaft 12 and is parallel to the center line of the driven shaft 30. Therefore, the acting force generated in the nut 13 passes through the center of the nut ball circulation path, and no reaction force moment is generated in the nut 13.

  FIGS. 4A and 4B are diagrams for explaining a second modification of the connection portion between the swing arm and the ball screw. FIG. 4A is a front view thereof, and FIG. 4B is a cross-sectional view thereof. The same members as those in the embodiment described above with reference to FIGS. 1 and 2 are denoted by the same reference numerals.

  4 (a) and 4 (b), the nut 13 is formed with two flat portions 13r and 13s on the left and right when viewed from the ball screw shaft 12 to be screwed, and in the center of the flat portions 13r and 13s. Circular holes 13j and 13k are respectively provided, and the axial centers of the circular holes 13j and 13k are orthogonal to the axial center of the ball screw shaft 12 and are located on a plane including the axial center of the ball screw shaft 12.

  The tip 21a of the swing arm 21 is formed with a circular hole 21g at a position corresponding to the circular hole 13j provided on the flat portion 13r of the nut 13, and the tip 21a of the swing arm passes through the circular hole 13j. It is rotatably attached around the pin 23a to be rotated. Similarly, the tip 22a of the swing arm 22 is formed with a circular hole 22g at a position corresponding to the circular hole 13g provided on the flat portion 13s of the nut 13, and the tip 22a of the swing arm is formed in the circular hole 13k. Is rotatably mounted around a pin 24a penetrating through the pin. The tip portions 21a and 22a of the swing arm are rotatably mounted around the cylindrical projections 13f and 13g, the swing center M of the swing arm includes the axis of the ball screw shaft 12, and the driven shaft It lies on a plane parallel to the 30 center line.

  Even with this configuration, even if the swing arm 21 tilts to the right or left, the swing center M of the swing arm 21 always includes the axis of the ball screw shaft 12 and is parallel to the center line of the driven shaft 30. Therefore, the acting force generated in the nut 13 passes through the center of the nut ball circulation path, and no reaction force moment is generated in the nut 13.

  In the embodiment of the invention described above, the ball screw device of the invention has been described as being applied to a power operating mechanism of a transmission for a vehicle. However, the ball screw device of the invention is a power of a transmission for a vehicle. Needless to say, the present invention is not limited to the operation mechanism and can be widely applied to a drive mechanism of a general mechanical device.

  A ball screw device that once converts the linear motion of the nut into the swing motion of the swing arm and then converts it back into a rotary motion to drive the driven body. A ball that includes the axis of the screw shaft of the screw mechanism and is on a plane parallel to the rotation axis center line of the swing arm, so that no reaction force moment is generated in the nut and the life of the ball screw mechanism can be extended. A screw device is provided.

The figure explaining the drive device comprised from the rocking | fluctuating arm and ball screw mechanism of embodiment of this invention. The figure explaining operation | movement of the drive device shown in FIG. The figure explaining the 1st modification of the connection part of a rocking | swiveling arm and a ball screw. The figure explaining the 2nd modification of the connection part of a rocking | swiveling arm and a ball screw. The figure explaining arrangement | positioning of the electric drive device for transmissions using the conventional ball screw apparatus. The figure explaining an example of the shift pattern of the operation lever of the transmission for vehicles shown in FIG. Sectional drawing in alignment with the AA line of the transmission for vehicles shown in FIG. The figure explaining the rocking | fluctuating arm and ball screw mechanism part of the conventional drive device. The figure explaining operation | movement of the conventional drive device shown in FIG.

Explanation of symbols

11 Ball screw device 12 Ball screw shaft 13 Nut 13a, 13b Groove 13c, 13d Protrusion part 13f, 13g Cylindrical protrusion 13j, 13k Circular hole 13p, 13q Receiving part 13r, 13s Plane part 14, 15 Ball bearing 17 Reduction gear mechanism 18 Motor 19 Housing 21, 22 Swing arm 21a, 22a Tip part 21f, 22f Circular hole 21g, 22g Circular hole 21A, 22A First member 21B, 22B Second member 21C, 22C Sliding connection part 30 Driven shaft

Claims (4)

A ball screw mechanism including a screw shaft, a nut screwed to the screw shaft, and a plurality of balls that circulate and move in a ball circulation path formed between the screw shaft and the nut;
A swingable arm capable of extending and contracting in the direction of the arm axis connecting the swingable driven shaft and the nut;
The swing arm is disposed on both sides of the nut, and includes two members: a first member that is rotatably attached to the nut and a second member that is fixed to a swingable driven shaft. consists only, the first member and the second member, the arm axis telescopically, in the direction intersecting the arm axis direction is coupled is inhibited movement,
The end of the first member connected to the nut is pivotably attached to the nut about a predetermined swing center, and the predetermined swing center is connected to the screw shaft. A ball screw device comprising an axis and on a plane parallel to the axis of the driven shaft. 2. The swing arm includes a coupling member having a substantially disk-shaped end on the side connected to the nut, and the nut includes a recess that fits into the coupling member. A ball screw device according to claim 1. 2. The swing arm includes a circular coupling hole at an end portion on a connection side with the nut, and the nut includes a protrusion that fits into the circular coupling hole of the swing arm. The ball screw device described. The swing arm includes a circular coupling hole at an end portion on a connection side with the nut, and the nut includes a hole to which a pin that fits into the circular coupling hole of the swing arm is fixed. The ball screw device according to claim 1, wherein the pin and the nut are coupled by the pin.

Images