JP2003307260A - Planetary roller reducer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reducer capable of preventing vibration generated from a reducing mechanism, preventing uneven rotation by additional fluctuation, and increasing a reduction gear ratio without increasing a size. <P>SOLUTION: This reducer is assembled such that it is constituted of an input shaft 2 for fixing and supporting a planetary roller 1 at its shaft end, an output shaft 4 having a cup-shaped shaft end 3, and a cylindrical case 5 having an inner peripheral length slightly longer than the outer peripheral length of the cup-shaped shaft end 3 for housing the input shaft 2 and the output shaft 4. The planetary roller 1 is press-fitted to the inner peripheral part of the cup-shaped shaft end 3, whereby the outer peripheral part of the cup-shaped shaft end 3 is expanded, and only the expanded part is brought into contact with the cylindrical case 5 by strong pressing force. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to deceleration of a driving force of a motor such as a printer of a personal computer, a copying machine, various OA equipment, etc., with a rotation speed fluctuation as small as possible.
The present invention relates to a deceleration mechanism that performs (increases speed). 2. Description of the Related Art Most of reduction gears used in power transmission units of personal computer printers and copiers use gears. In addition, toothed belt belts or stainless steel belts are used. Some are used. [0003] In the case of using gears, noise or vibration is generated due to the characteristics of the teeth, and in the case of a printer or the like requiring rotation accuracy, the influence of the vibration adversely affects the image quality. [0004] In the case of using a toothed belt, speed fluctuation occurs due to a change in the length of the belt due to a change in load of the apparatus because the rigidity of the belt is low. [0005] Those using a stainless steel belt can transmit the rotation with good accuracy, but the transmission load capacity is low and the structure becomes large. In particular, when the reduction ratio increases, the diameter of the pulley on the output side becomes twice the reduction ratio of the pulley on the input shaft side. Since the strength of the stainless steel belt is proportional to the diameter of the pulley, it cannot be made too small. For example, a stainless steel belt having a plate pressure of about 0.04 mm requires a pulley diameter on the input shaft side of about 14 mm. On the other hand, since the reduction ratio of the motor often requires 20 to 25 times, the pulley diameter on the output side becomes too large. For this reason, two-stage deceleration is required, and the structure becomes complicated, which is likely to cause a failure. In addition, since stainless steel belts are not so popular, they are expensive and are therefore only used for high-end large models. [0006] It is an object of the present invention to prevent the vibration in the power transmission system, improve the rigidity in the power transmission system, and improve the transmission load capability with respect to the size of the reduction gear, which are the above-mentioned problems. Things. It is another object of the present invention to provide a deceleration drive mechanism which is simple, reduces the number of parts, is small and lightweight, and is suitable for mass production. An input shaft (2) for fixedly supporting a planetary roller (1) at the shaft end, an output shaft (4) having a cup-shaped shaft end (3), A cylindrical case (5) having an inner peripheral length that is slightly longer than the outer peripheral length of the cup-shaped shaft end (3), and the inner periphery of the cup-shaped shaft end (3) By press-fitting the planetary roller (1), the outer peripheral portion of the cup-shaped shaft end (3) expands, and this is further assembled so that only the expanded portion comes into contact with the cylindrical case (5) with a strong pressing force. The speed reduction device. Embodiment 1 An embodiment of a planetary roller speed reducer provided by the present invention will be described based on an embodiment with reference to the drawings. In FIG. 1, (1) is a planetary roller, and (2) is an input shaft that supports the roller. The roller is supported by a roller case (7) at a center by a roller shaft (6). A bearing bush (8) is provided between the roller (1) and the roller shaft (6) so that the roller (1) can rotate smoothly. Press-fit. In this structure, the roller and the bearing bush can be replaced with a ball bearing or a roller bearing. A washer (10) is provided between the roller case (7), the roller (1) and the bearing bush (8) so that the roller (1) can rotate smoothly on both sides thereof. 6). One end of the roller shaft (6) has a large diameter like a flange, and the other end is fixed by caulking in a mortar-shaped hole (11) formed in the roller case (7). I have. A spline hole (12) is formed in the center of the roller case (7), and a spline shaft (13) provided at an end of the input shaft (2) is fitted therein. . At both ends of the roller case (7), the input shaft (2) is fitted into snap ring grooves (14) (15) formed on the outer periphery of a spline shaft (13) of the input shaft (2). The snap rings (16) and (17) are fixed so that they cannot move in the longitudinal direction. The circumscribing diameter of the two rollers (1) rotatably mounted on the roller case (7) integrated with the input shaft (2) is shown in FIG. It is press-fitted into the inner diameter of the shaft end (3). The cup-shaped shaft end (3) is in a completely cylindrical state in a free state before assembly, and has an inner diameter smaller than the circumscribed diameter of the two rollers (1). The cup-shaped shaft end (3) is connected to the output shaft (4).
The male spline (18) provided at the shaft end is press-fitted to a female spline (19) machined to the inside diameter of the central shaft projection portion of the cup-shaped shaft end (3) which is narrowed down. The two rollers (1) rotatably mounted on the roller case (7) integrated with the input shaft (2) are press-fitted into the inner diameter of the cup-shaped shaft end (3). The largest outer part in the state that was set is a cylindrical case (5).
Is larger than the inner diameter in the free state. For this reason, in the assembly of the input / output shaft, the mechanical relationship between the rigidity of the input / output shaft and the rigidity of the cylindrical case (5) is determined in a state where the external shape of the cylindrical case (5) is deformed by applying force. It will be in a balanced state. A plate (20) supports the output shaft. A bush (21) for smoothing the rotation of the output shaft (4) is press-fitted into the inner diameter portion, and the outer portion is a cylindrical case (5). Fitted to the inside diameter, it is stopped by a large snap ring (22). The operation of the planetary roller speed reducer provided by the present invention will be described. Suppose now a cylindrical case (5)
Is fixed so as not to rotate, and the contact surface between the cylindrical case (5) and the cup-shaped shaft end (3) is pressed while pressing the input shaft (2) in the outer diameter direction in FIG. Rotate so that it does not slip. Since the circumference of the cylindrical case (5) and the cup-shaped shaft end (3) is shorter at the cup-shaped shaft end (3), it rotates counterclockwise accordingly. Now, suppose that the ratio of the circumference of the cylindrical case (5) to the circumference of the cup-shaped shaft end (3) is 1
When the ratio is 0: 9, the cup-shaped shaft end (3) rotates reversely by 10% of the difference in length, so that the reduction ratio for the input shaft (2) is 10. Further, when the ratio of the peripheral length between the cylindrical case (5) and the cup-shaped shaft end (3) is set to 20:19, the cup-shaped shaft end (3) has a difference in length. Since the motor rotates reversely by 5%, the speed reduction ratio is 20. Here, if the circumference of the cup-shaped shaft end (3) is close to the inner circumference of the cylindrical case (5), a large reduction ratio can be easily obtained. If the relationship between the input shaft and the output shaft is temporarily reversed, the speed reducer becomes a speed increaser. Further, here, the cylindrical case (5) is rotationally fixed, but this relationship also holds for the input shaft (2) or the cup-shaped shaft end (3), respectively, with the two remaining shafts fixed. Each element can be an input axis and an output axis, so that a total of six combinations can be made. Embodiment 2 FIG. 3 shows another embodiment. In this example, the number of the planetary rollers (23) is four, and the input reaction force generated between the cup-shaped shaft end (24) and the cylindrical case (25) increases as the reduction ratio increases. Therefore, by increasing the number of the planetary rollers, the surface pressure generated between them can be reduced. When the planetary roller (1) makes one rotation in the clockwise direction, the planetary roller (1) presses the inner diameter of the cup-shaped shaft end (3) in the outer diameter direction and the cylindrical case (5) and the cup-shaped shaft end (3). Rotate so that the contact surface does not slip. Since the circumference of the cylindrical case (5) and the cup-shaped shaft end (3) is shorter at the cup-shaped shaft end (3), it rotates counterclockwise accordingly. Now, suppose that the ratio of the circumference of the cylindrical case (5) to the circumference of the cup-shaped shaft end (3) is 1
When the ratio is 0: 9, the cup-shaped shaft end (3) rotates reversely by 10% of the difference in length, so that the reduction ratio for the input shaft (2) is 10. Further, when the ratio of the peripheral length between the cylindrical case (5) and the cup-shaped shaft end (3) is set to 20:19, the cup-shaped shaft end (3) has a difference in length. Since the motor rotates reversely by 5%, the speed reduction ratio is 20. Here, if the circumference of the cup-shaped shaft end (3) is close to the inner circumference of the cylindrical case (5), a large reduction ratio can be easily obtained. If the relationship between the input shaft and the output shaft is temporarily reversed, the speed reducer becomes a speed increaser. Further, here, the cylindrical case (5) is rotationally fixed, but this relationship also holds for the input shaft (2) or the cup-shaped shaft end (3), respectively, with the two remaining shafts fixed. Each element can be an input axis and an output axis, so that a total of six combinations can be made. Embodiment 2 FIG. 3 shows another embodiment. In this example, the number of the planetary rollers (23) is four, and the input reaction force generated between the cup-shaped shaft end (24) and the cylindrical case (25) increases as the reduction ratio increases. Therefore, by increasing the number of the planetary rollers, the surface pressure generated between them can be reduced. [Embodiment 3] Although not shown, the number of planetary rollers does not depend on the number described above, and it is possible to easily set a larger number, even if it is one other than two or four. As described above, the input shaft (2) for fixedly supporting the planetary roller (1) at the shaft end and the output shaft (4) having the cup-shaped shaft end (3) are provided. A cylindrical case (5) having the inner peripheral length thereof slightly longer than the outer peripheral length of the cup-shaped shaft end (3), the inner periphery of the cup-shaped shaft end (3). By press-fitting the planetary roller (1) into the portion, the outer peripheral portion of the cup-shaped shaft end (3) swells, and only this swelling portion contacts the cylindrical case (5) with a strong pressing force. With the speed reducer assembled as described above, since the roller rotation does not cause vibration, rotation vibration and rotation unevenness can be prevented. As a result, it is possible to cope with production as a reduction gear such as a mass-produced printer at a low price. Since the planetary rollers and the cup-shaped shaft ends have extremely high rigidity, they do not expand due to the load torque, so that there is no rotation fluctuation in the reduction gear due to load fluctuations. Furthermore, a large reduction ratio can be easily obtained by shortening the difference between the outer circumference of the cup-shaped shaft end (3) and the circumference of the cylindrical case (5). . In contrast to gears, toothed belts, stainless steel belts, etc., which have only one power transmission point, the present invention provides two positions for two rollers and two positions for three rollers. By increasing the number of three rollers and the number of rollers, the number of power transmission points can be increased, so that a large transmission capacity can be exhibited for a small external shape.

[Brief description of the drawings] FIG. 1 of the present invention. FIG. 2 is a sectional view taken along line BB. FIG. 2 of the present invention. FIG. 1 is a view taken in the direction of arrows AA. FIG. 3 is a sectional view of a second embodiment of the present invention. [Main parts name] 1 ··· Planetary roller 2. Input shaft 3 .... the cup-shaped shaft end 4 Output shaft 5. Cylindrical case

Claims (1)

Claims: 1. An input shaft (2) for fixedly supporting a planetary roller (1) at a shaft end, an output shaft (4) having a cup-shaped shaft end (3), and internal components thereof. The cup-shaped shaft end (3)
And a cylindrical case (5) having an inner peripheral length slightly longer than the outer peripheral length of the cup, by press-fitting the planetary roller (1) into the inner peripheral portion of the cup-shaped shaft end (3). A reduction gear assembled such that the outer peripheral portion of the cylindrical shaft end (3) swells, and further only the swelling portion comes into contact with the cylindrical case (5) with a strong pressing force.