JPH0356751A - Electric linear driving device - Google Patents

Abstract

PURPOSE:To enlarge the field of application with increase in the function and to make the whole apparatus compact by forming a flat surface parallel to the axis of a ball screw shaft, and engaging a rotation preventing portion of a rotation transmitting member mounted on a housing with the flat surface. CONSTITUTION:A flat surface 3 parallel to the axis is formed on a ball screw shaft 1, and a rotation preventing portion of a rotation transmitting member 24 mounted on a housing 6 is engaged with the flat surface 3. When a ball screw nut 5 is rotated by an electric motor 12, with the rotation transmitting member 24 stopped, the ball screw shaft 1 is moved linearly. When the rotating speed of the ball screw nut 5 and the rotation transmitting member 24 is changed, the ball screw shaft 1 makes a compound motion of linear motion and rotation. Thus, the field of application can be enlarged by increasing the function, and the whole apparatus can be made compact.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is an electric linear drive device that converts the rotational motion of an electric motor into linear motion, and in particular uses a pole screw in the threaded portion and a linear motion on the ball screw shaft. This article relates to an electric linear drive device that can provide rotation and combined motion. [Prior art] Conventionally, as an electric linear drive device, for example,
Some of these are described in Publication No. 342 and Japanese Unexamined Patent Publication No. 165057/1982. In the former conventional example, a ball screw groove is formed in one half of the ball screw shaft, a spline groove is formed in the other half, a ball screw nut is engaged with the ball screw groove, and a ball spline is held in the spline groove. By driving the ball screw nut with an electric motor, the ball screw shaft is configured to move forward and backward in a straight line while preventing rotation. The latter conventional example has a ball screw groove and a spline groove, a ball screw nut and a ball splinenant, and the screw shaft is advanced by the rotation of the ball screw nut, and the screw is moved by driving the ball spline nut with a rotation mechanism. It is configured to rotate around the axis. [Problems to be Solved by the Invention] Incidentally, in any of the conventional devices described above, the length of the ball screw shaft is longer than its stroke, which increases the size of the entire device and increases the manufacturing cost. There is a problem. An object of this invention is to shorten the length of the ball screw relative to the stroke, thereby downsizing the entire device, and to provide the ball screw shaft with linear motion, rotation, and a combination of these motions, in order to solve the conventional problems. The aim is to provide an electric linear drive device that can be used to expand the range of applications. [! Means for Solving Problem 18] In order to solve the above problems, the present invention provides a ball screw shaft having a flat surface parallel to the axis on the outer circumferential surface provided with a thread groove, and a ball screw shaft that is externally fitted to the pole-free shaft. A ball screw nut that rotatably stores and holds a ball that engages in a groove, an electric motor that rotationally drives the ball screw nut, a housing that supports the electric motor, and a ball that is coaxial with the ball screw shaft. It consists of a rotation transmission member rotatably supported by a housing so as to be fitted onto the outside, and the rotation transmission member is provided with a rotation prevention part that engages with the flat surface of the ball screw shaft. .

[Effect]

In this invention, the pole fixed shaft is formed with a flat surface parallel to the axis, and the rotation preventing portion of the rotation transmission member attached to the housing is engaged with the flat surface to stop the rotation transmission member. When the ball screw nut is rotated by an electric motor in this state, the ball screw shaft will move in a direct motion. Furthermore, when the ball screw nut and the rotation transmission member are rotated at a constant speed, the ball screw shaft only rotates, and when the rotation speed of the ball screw nut and the rotation transmission member is further changed,
The ball screw shaft performs a combination of linear and rotational motion. [Example] Hereinafter, an example of the present invention will be described based on the attached drawings. FIG. 1 is a longitudinal sectional view of the electric linear drive device, and in the same figure, ball screw grooves 2 with a predetermined pitch are provided on the outer peripheral surface of the pole shaft 1, and a flat surface parallel to the axis. 3 are arranged in four rows in the axial direction at equal circumferential locations. The flat surface 3 is set to be shallower than the bottom of the ball screw groove 2 so that rolling of the ball 4 on the inner circumference of the ball screw groove 2 is not hindered. A cylindrical ball screw nut 5, which accommodates and holds the balls 4 in an endless manner so as to be rotatable, is rotatably supported on the inner periphery of the housing 6 via bearings 7, 7 while being fitted onto the ball screw shaft 1. Note that 8 is a collar for positioning the bearings 7, 7, and 9 is a locking nut for fixing the bearings 7, 7 through a spacer 10. A ball screw groove 11 is screwed into the inner peripheral surface of the ball screw nut 5, and a ball circulation part 11a is provided on the outer peripheral surface, which is formed by the ball screw groove 11 and the ball screw groove 2 of the ball screw shaft 1. A large number of balls 4 are incorporated in the ball passage and the pole circulation section 11a so as to be able to roll and circulate freely. On the other hand, a rotor 12a of a permanent magnet electric motor 12, which serves as a rotational drive mechanism that applies rotational force to the ball screw nut 5, is fitted onto the outer peripheral surface of a cylindrical rotor yoke 5a that extends integrally with the ball screw nut 5. 12b is a coil, and t2c is a stator fixed to the inner peripheral surface of the housing 6. 13 is ball screw nut 5
A rotary encoder detects the rotational phase angle of the rotary encoder, and 14 is a seal. Furthermore, a cylindrical holder 21 is attached to one end of the housing 6 so as to be rotatable via a bearing 22, and is fitted coaxially with the ball screw shaft 1. The rotation prevention member 23 and the rotation transmission member 24
is fixed. FIG. 2 shows the first part of the rotation preventing member 23.
This embodiment is made up of two half-split disk-shaped members 25, 25 arranged on both sides of the ball screw shaft 1, and a ball screw is attached to the inner peripheral surface of both disk-shaped members 25, 25. @1
A flat surface 26 serving as a rotation prevention portion corresponding to the flat surface 3 is provided. By adjusting the gap between the mating portions 27 of the disc-shaped members 25, 25, the gap between the two flat surfaces 3, 26 is changed, and the sliding resistance of the ball screw shaft 1 is controlled. Therefore, the mounting hole 28 has a fixing bolt (
The shaft diameter is slightly larger than that of the shaft (not shown), and the positions of the disc-shaped members 25, 25 can be adjusted freely. When a moment force is applied to the ball screw shaft 1, only the ball rolling portion of the ball screw nut 5 supports it, but by providing the anti-rotation member 23 at a position away from the ball rolling portion, this rotation is supported. Even the regular member 23 can support moment forces in all directions. FIG. 3 shows a second embodiment of the anti-rotation member 23. The same parts as those in the first embodiment shown in FIG. 2 are given the same reference numerals and their explanation will be omitted. This anti-rotation member 23 is composed of half-split disk-shaped members 25, 25, as in the first embodiment, and four twenty-one dollar bins 29 are fixed to the inner peripheral surface thereof to prevent rotation. That is, the second bin 29 is
It is fixed at a position corresponding to the flat surface 3 of the ball screw shaft 1,
There will be a line contact with flat surface 3. Therefore, in the case of this embodiment, the ball screw shaft 1 can be slid while the gap between the mating portions 27 is closed and a light preload is applied, and the play of the ball screw shaft 1 can be suppressed as much as possible.

FIG. 4 shows a third embodiment of the rotation member 23, and if the direction of the moment acting on the ball screw shaft 1 is determined, rotation can be prevented by two lines in this way.

In the same figure, reference numeral 31 denotes a rotation preventing member on which a pair of fingers 32 that are externally fitted onto the ball screw shaft 1 are protruded. Rotation is prevented by making contact with 3. Therefore, the ball screw shaft 1 of this embodiment has flat surfaces 3 formed on both sides. A slit 33 is formed between the fingers 32 of the anti-rotation member 31, and even if a slight installation error occurs, it can be absorbed by the spring action. Further, 34 is an adjustment bolt, and by tightening it, the sliding resistance of the ball screw shaft 1 can be freely adjusted. 35 is a long hole for attaching the rotation prevention member 31 to the holder 21. The rotation transmission member 24 is formed in a ring shape that fits around the rotation prevention member 23, and is connected to the ball screw shaft 1.
It is fixed to the holder 21 so that the coaxial center alignment is 1q. Although this rotation transmission member 24 has teeth in the case of FIG. 1, it may also be a boob with a groove on the outer periphery, and although not shown, it can be linked with a rotational drive mechanism as appropriate to impart rotation. It looks like this.

The electric linear drive device of the present invention has the above-described configuration, and when the electric motor 12 is energized and started with the rotation transmission member 24 stopped, the ball screw nut 5 rotates.
The pole shaft 1, which is held in a non-rotating state by the anti-rotation member 23, is linearly driven in the axial direction by the feeding action of the ball 4 and the screw groove 2.

The ball screw shaft 1 moves in the axial direction while its flat surface 3 slides against the rotation prevention member 23, and precise positioning can be achieved by the sliding resistance generated by the rotation prevention mechanism. Next, simultaneously with the rotation of the 71-mile screwdriver 5 by the electric motor 12, the rotation transmission member 24 is rotated by an external drive source.
By rotating the ball screw shaft 1, rotation or a combination of rotation and linear motion can be imparted to the ball screw shaft 1. That is, when the ball screw nut 5 and the rotation transmission member 24 are rotated at a constant speed, the rotation prevention member 23 does not have a rotation prevention function, so that the ball screw shaft 1 rotates at a fixed position while being stopped in the axial direction. Furthermore, when the rotational speed of the rotation transmission member 24 is changed with respect to the ball screw nanometer 5, the rotation preventing member 23 rotates with respect to the ball screw shaft 1 while exerting a rotation prevention function, so that the ball screw shaft 1! ! ] Compound interlocking of single rotation and linear motion will be performed.

Next, Table 1 shows the relationship between the control of the rotational input of the ball screw nut 5 and the rotation transmission member 24 and the output of the ball screw shaft 1 as described above. [Effects] With the above configuration, the present invention exhibits special effects as an electric linear drive device as described below. (stomach). By controlling the rotational input of the ball screw nut and the rotation transmission member, it is possible to impart linear motion and rotation, and compound motion of linear motion and rotation, to the ball screw shaft, and the expansion of functions expands the field of application. (b) The length of the ball screw shaft relative to the required stroke can be shortened, making the entire device simple and compact. Q→． It is possible to prevent the rotation of the ball screw shaft with a simple IJI precept, and without reducing the rigidity of the ball screw shaft.
It is also easy to process.

(d). Not only can the sliding resistance of the ball screw shaft be easily adjusted, but also the moment force acting on the ball screw shaft can be received.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of an electric linear drive device according to the present invention;
FIG. 2 is a longitudinal side view showing a first embodiment of the rotation prevention IL section used in the above, and FIGS. 3 and 4 are longitudinal side views showing the second and third embodiments of the rotation prevention section. This is a diagram. 1...Ball screw shaft, 2, 11...Ball screw groove, 3, 16...Flat surface, 4...
... Pole, 5 ... Ball screw nut, 6 ... Housing, 12 ... Electric motor, 21 ... Holder 22 ... Bearing, 23 ... Rotation prevention member, 24 ... Rotation transmission member.

Claims (4)

[Claims] (1) A ball screw shaft having a flat surface parallel to the axis on the outer peripheral surface provided with a threaded groove, and a ball that fits externally on the ball screw shaft and engages with the threaded groove are housed and held in an endless manner so as to be able to freely roll. The ball screw nut is comprised of a ball screw nut, an electric motor that rotationally drives the ball screw nut, a housing that supports the electric motor, and a rotation transmission member that is rotatably supported by the housing so as to be coaxially fitted onto the ball screw shaft. , an electric linear drive device in which the rotation transmission member is provided with a rotation prevention portion that engages with a flat surface of a ball screw shaft. (2) The flat surface formed on the outer peripheral surface of the ball screw shaft is
The electric linear drive device according to claim 1, wherein the electric linear drive device is set shallowly with respect to the thread groove. (3) The electric linear drive device according to claim 1, wherein the rotation prevention portion provided on the rotation transmission member is formed of a flat surface that engages with a flat surface of a ball screw shaft. (4) The electric linear drive device according to claim 1, wherein the rotation prevention portion provided on the rotation transmission member is formed of a needle pin that engages with a flat surface of a ball screw shaft.