JP3028989B2 - Linear motion mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear motion mechanism for converting a rotary motion widely used in, for example, an industrial robot or a transfer device into a linear motion.

[0002]

2. Description of the Related Art Conventionally, as a device for converting a rotary motion into a linear motion, a rack 2 having a plurality of teeth 2a engraved on a linear member as shown in FIG. There is known a rack and pinion mechanism including a pinion 1 (gear) having the teeth 1a. Further, as shown in FIG. 2, there is known a pin gear device including a rack 3 having corrugated teeth 3a and a pin gear 4 in which a number of pins 4a meshing with the rack 3 are planted on a disk.

[0003]

In the above-described conventional linear motion mechanism, the rack slides on the tooth surface of the rack and the pinion or slides between the tooth surface of the rack and the pin on the disk. And the problem of pinion tooth surface wear.

In addition, one tooth of a pinion or one of a disc
Since the pins of the book are in mesh with the teeth of the rack, there is a problem that the backlash between the rack and the pinion and the backlash between the rack and the pin of the disk are large, and the transmission efficiency is reduced.

Further, in the above-mentioned pin rack structure, it is necessary to plant four or more pins on the disk due to the structure. On the other hand, if the pin is thin to engage the teeth of the rack with the pins, For this reason, there is a problem that a large load cannot be transmitted.

[0006]

SUMMARY OF THE INVENTION In the present invention, a passive rack having three corrugated tooth profiles in upper and lower three stages with a phase difference of 120 ° and three cranks with a phase difference of 120 ° are provided. has a part, rotatable crankshaft, and Ri Do of three rollers rotatably supported via a bearing on three crank portion of the crankshaft, the three rollers
There is achieved by linear movement mechanism characterized that you have contact with the driven rack.

[0007]

According to the present invention, the passive rack has three corrugated tooth shapes and the phases are different from each other by 120 ° and are arranged in three upper and lower stages.
By displacing the three rollers on the crankshaft in the axial direction and displacing the respective phases by 120 ° with a certain amount of eccentricity from the center of the rotating shaft, linear movement is possible and the roller diameter can be increased, Can withstand heavy loads.

Further, a bearing is arranged inside the roller,
By adopting the rolling transmission, it is possible to improve wear resistance and efficiency.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the accompanying drawings. FIG. 3 shows a perspective view of an embodiment of the rectilinear motion mechanism according to the present invention, in which the cover is removed.

As shown in FIG. 3, a case or a main body 10 having a rack supporting portion is fixedly supported on the inner wall thereof, and a linear passive rack 11 is supported on the case or the main body 10 by a slide bearing 9 so as to be able to move linearly. Have been. On the side surface of the passive rack 11, a corrugated tooth shape 11a, 1
1b and 11c are formed in upper and lower three stages.
1a, 11b and 11c are trochoid curves or cycloid curves as shown in FIG. The upper and lower three-stage corrugations 11a, 11b, and 11c have a phase of 1
20 ° different.

In FIG. 3, one crankshaft 12 is rotatably supported by a case or a main body 10 on a side of a passive rack 11 by known appropriate means.

The crankshaft 12 is formed with three crank portions (not shown) in the axial direction. The three crank portions have the same eccentricity from the center axis of the crankshaft 12, ie, When viewed in the axial direction of the crankshaft 12, the three crank portions are on a circle having a constant radius from the center axis, and the two adjacent crank portions have a phase difference of 120 °.

Rollers 13 are rotatably supported by the crank portions of the crankshaft 12 via bearings 14, respectively.

When the crankshaft 12 is rotated, the rollers 13 provided on the crankshaft 12 mesh with the tooth profiles 11a, 11b, 11c of the passive rack 11, and the passive rack 11 moves linearly. At this time, the roller 13 and the passive rack 11
Are in rolling contact with the tooth profiles 11a, 11b, 11c. The upper and lower corrugations 11a, 11a of the passive rack 11
b and 11c have a phase difference of 120 °, and the roller 13 rotatably supported on the crankshaft 12 also has a phase difference of 120 °, so that the upper and lower corrugations 11a, 11b, 1
1c and the three rollers 13 of the crankshaft 12 are continuously engaged. In addition, since no gear is used to link the upper and lower rollers 13, no backlash occurs.

[0015]

According to the present invention, the passive rack has three corrugated tooth profiles, and the three phases are arranged in the upper and lower stages with a phase difference of 120 °, and the three rollers are displaced in the axial direction on the crankshaft. The phases are shifted by 120 ° and three
By bringing the roller into contact with the passive rack, it is possible to perform a curved motion, making it possible to increase the roller diameter.
Can withstand heavy loads.

Further, a bearing is arranged inside the roller,
By adopting the rolling transmission, it is possible to improve wear resistance and efficiency.

[Brief description of the drawings]

FIG. 1 is a plan view showing a conventional rack and pinion mechanism.

FIG. 2 is a plan view showing a conventional pin rack device.

FIG. 3 is a perspective view of the embodiment of the present invention with a cover removed.

FIG. 4 is a diagram illustrating a tooth profile of a rack according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Passive rack 11a, 11b, 11c Wave type 12 Crankshaft 13 Roller 14 Bearing

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-160258 (JP, A) JP-A-1-65973 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16H 19/00-19/04

Claims (1)

(57) [Claims] 1. A passive rack having three corrugated tooth profiles in upper and lower stages with a phase difference of 120 °, a crankshaft having three crank portions with a phase difference of 120 °, and a rotatable crankshaft, and the crank Ri Do of three rollers rotatably supported on three crank portion of the shaft through the bearing, the three b
Linear motion mechanism is over La characterized that you have contact with the driven rack.