JP3003739U - Motor screw - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a ball screw having a novel structure that does not apparently occupy a space that is a motor as a drive unit, has a simple structure, and can be downsized. [Structure] A ball screw includes a hollow cylindrical screw shaft 10 having a thread groove 11 formed on an outer peripheral surface thereof, a ball nut 20 fitted to the screw shaft by engaging a thread groove 23, and a center of both ends of the screw shaft. Center shafts 15 and 15 'that rotatably support the hollow screw shaft, a motor 13 and a rotary encoder 40 housed in the hollow screw shaft, and a planet that transmits the rotation of the motor to the screw shaft. And a gear 14.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a so-called motor screw that linearly drives a ball nut fitted by engaging a screw groove with a screw shaft by rotating a screw shaft having a screw groove formed on a peripheral surface.

[0002]

[Prior art]

 Conventionally, in a motor screw that linearly drives a ball nut fitted into a screw shaft having a thread groove by engaging the screw groove with each other, a screw shaft having a thread groove on the outer peripheral surface is used, for example. A structure in which a ball nut, which is connected to the rotary shaft of a drive unit such as a loose motor by a coupling or the like, and which is engaged with a screw groove and is linearly moved back and forth, is generally used. .

[0003]

[Problems to be solved by the device]

 However, in the conventional motor screw having the above-mentioned structure, its structural feature, that is, the structure in which a hollow screw shaft having a thread groove formed on the outer peripheral surface is connected to the rotation shaft of an external pulse motor, Apparently, the drive unit is located on the side of the motor screw and occupies the space, which hinders the miniaturization of the motor screw.

Therefore, in the present invention, in view of the above-mentioned conventional technique, a motor having a novel structure capable of eliminating a space occupying the appearance of a motor that is a drive unit, simplifying, and downsizing can be obtained. Its purpose is to provide a screw.

Further, according to the present invention, it is an object of the present invention to provide a motor screw capable of detecting the position with higher accuracy by making the outer diameter portion of the rotary encoder thicker.

[0006]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention proposes a screw shaft having a thread groove formed on a peripheral surface thereof, a ball nut fitted to the screw shaft by engaging the thread groove, and the screw shaft. In a ball shaft equipped with a motor for rotating the hollow shaft, a cylindrical hollow screw shaft having a thread groove formed on the outer peripheral surface and the hollow screw shaft are provided at the centers of both ends of the hollow screw shaft so that the hollow screw shaft is rotatable. A supporting center shaft, a motor housed in the hollow screw shaft, a transmission mechanism for transmitting the rotation of the motor to the hollow screw shaft, and a rotary encoder for detecting a rotation angle, and an outer periphery of the hollow screw shaft. With a ball nut that fits in the thread groove A motor screw.

[0007]

[Action]

 That is, according to the structure of the motor screw according to the present invention described above, a motor for rotationally driving a screw shaft having a thread groove formed on the outer peripheral surface that linearly moves the ball nut is provided, and a screw groove is formed on the outer surface. By arranging it inside the formed cylindrical hollow screw shaft, there is no space for the motor, which is the drive part, to occupy the outside of the entire motor screw, thus simplifying the motor screw. , Enables its miniaturization.

[0008]

【Example】

 Hereinafter, details of embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 shows a motor screw according to an embodiment of the present invention. In this figure, a cylindrical screw shaft 10 having a thread groove 11 on its outer peripheral surface is engaged with the thread groove 11. A ball nut 20 having a flange portion 22 formed on a part of the cylindrical portion 21 is fitted. That is, a thread groove 23 is formed on the inner peripheral surface of the ball nut 20, similarly to the outer peripheral surface of the screw shaft 10. In the motor screw having such a structure, as with the conventional motor screw, the ball nut 20 is converted in the left and right directions of the drawing, that is, the rotational motion is converted into the linear motion (linear) motion as the screw shaft 10 rotates. It is a thing. This is indicated by an arrow in the figure.

By the way, according to the present invention, a motor for driving the screw shaft 10 to rotate, more specifically, a DC motor, a pulse motor or a servomotor (with each brake) is provided with the cylindrical screw shaft. It is arranged in 10 hollow parts. Details of the internal structure of the screw shaft 10 incorporating the motor will be described below with reference to FIGS. 1 and 2 described above.

In these figures, the screw groove 11 is formed on the outer peripheral surface of a cylindrical shaft 12 that constitutes the screw shaft 10. Further, inside the cylindrical shaft 12, a motor 13 as a rotary driving device, that is, a DC motor, a pulse motor or a servo motor is arranged. In this embodiment, a pulse motor or a servomotor (with each brake) is adopted. This is to control the position of the ball nut 20, which precisely controls the rotation and makes it precise, especially when the rotation is converted into a motion in a straight direction.

A three-stage planetary gear 14 and a non-backlash reduction mechanism are connected to the output shaft 131 of the motor 13, and the planetary gear 14 reduces the rotational speed to a predetermined rotational torque. And the output is transmitted to the internal gear 141. The internal gear 141 is supported on the center shaft 15 of the screw shaft 10 by bearings 17, 17. The center shaft 15 and the cylindrical shaft 12 are rotatably supported by bearings 17, 17 on the other hand, and the center shaft 15 is fixed, whereby the cylindrical shaft 12 is prevented. It will rotate at a predetermined rotation speed.

On the other hand, bearings 17, 17 are also provided at the end of the cylindrical shaft 12 on the side opposite to the side on which the planetary gears 14 are arranged. It is rotatably supported on the shaft 15 '. A power cable 30 for the motor, for example, is provided at the center of the other center shaft 15 '. A power supply bushing 31 is provided at the tip of the power supply cable 30, and a drive fixedly arranged in the rotating cylindrical shaft 12 by cables 32, 32, and 32 extending from the power supply bushing 31. Power is supplied to the motor 13, which is a device.

Next, FIG. 3 shows a motor screw according to an embodiment of the present invention. Also in this embodiment, the same components as those in the embodiment shown in FIGS. 1 and 2 are designated by the same reference numerals. In the motor screen according to this embodiment, as is clear from the figure, a part of the outer circumference of the cylindrical shaft 12, more specifically, one end (left end) thereof, and a large diameter. Part 40 is provided with a rotary encoder.

According to the motor screw of this embodiment, it is an object of the present invention to provide a motor screw capable of highly accurate position detection by the rotary encoder of the large diameter portion 40 at the left end of the figure.

[0015]

[Effect of device]

 As is clear from the above detailed description of the present invention, according to the motor screw of the present invention, there is no apparent space occupied by the motor, which is the drive unit, and the structure is simplified and greatly reduced. It also has a practically excellent effect that it can be miniaturized.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing details of the internal structure of a motor screw according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional perspective view showing the internal structure of the motor screw according to the above embodiment, particularly the hollow screw shaft.

FIG. 3 is a diagram showing details of an external structure of the motor screw according to the embodiment of the present invention.

[Explanation of symbols]

 10 Screw Shaft 11 Screw Groove 13 Motor 14 Planetary Gear 15, 15 'Center Shaft 20 Ball Nut 40 Rotary Encoder

Claims (1)

[Scope of utility model registration request] 1. A ball shaft comprising a screw shaft having a thread groove formed on a peripheral surface thereof, a ball nut fitted to the screw shaft by engaging the thread groove, and a motor for rotationally driving the screw shaft. A cylindrical hollow screw shaft having a thread groove formed on its surface, a center shaft provided at the center of both ends of the hollow screw shaft and rotatably supporting the hollow screw shaft, and housed in the hollow screw shaft. A motor, a transmission mechanism that transmits the rotation of the motor to the hollow screw shaft and a rotary encoder that detects a rotation angle, and a ball nut that is fitted by engaging with a screw groove on the outer periphery of the hollow screw shaft. Characteristic motor screw.