JP3524031B2 - Power transmission device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power source for a high-speed rotating transmission or transmission having a belt and a pulley (or roller) in a machine tool or an automatic machine. The present invention relates to a transmission device . 2. Description of the Related Art In recent years, machine tools and automatic machines having a high-speed rotation mechanism exceeding 20,000 rpm have been rapidly increasing. However, an inexpensive and highly efficient transmission capable of increasing the rotational speed of an ordinary motor of 5,000 rpm or less to a high speed of 20,000 rpm or more, and an inexpensive and highly efficient transmission capable of transmitting such a high-speed rotational torque. Has not yet been developed. Therefore, usually, a spindle motor that rotates at a high speed of 20,000 rpm or more is used, and the motor shaft is directly connected to a driven object. However, a high-speed rotating spindle motor is extremely special and expensive, and is structurally weak against vibration and impact applied to the motor shaft, and has a large inertia of the rotating mechanism of the motor. There is a problem that it takes time to stop acceleration and rotation. Therefore, there is a strong demand for an inexpensive and highly efficient power transmission device for high-speed rotation. [0007] In a conventional power transmission device having a belt and a pulley, a large centrifugal force acts on the belt with high-speed rotation, so that the belt easily floats from the pulley. When the belt is easily lifted from the pulley, the frictional force between the belt and the pulley is reduced, so that transmission of rotational torque becomes impossible. Therefore, a large tension is required for the belt in order to secure a frictional force capable of transmitting the rotational torque between the belt and the pulley. However, the load due to the large tension of the belt is the largest cause of shaft breakage during high-speed rotation. FIG. 8 illustrates a prior art power transmission device having a typical pulley and belt. The power transmission includes a drive pulley 2 fixed to a drive shaft 1.
Then, an endless belt 5 is wound around the pulley 4 fixed to the shaft 3 with an appropriate tension, and rotational torque is transmitted from the driving pulley 2 to the pulley 3 via the belt 5. In FIG. 8, when the radius of the pulley is r, the rotational angular velocity is w, and the weight per unit length of the belt is m, the centrifugal force f applied to the unit length of the belt is f = mrw
It becomes ² . Therefore, the minimum tension F1 of the belt generated by the centrifugal force is F1 = mr ² w ² , and the minimum load 2F1 generated on the drive shaft is 2F1 = 2 mr ² w ² . As a specific example, a rotation speed of 50,000 rpm
(Rotational angular velocity w = 5233 rad / s), radius r of pulley r = 0.05 m, weight m per unit length of belt = 3
In the case of g / cm, the minimum belt tension generated by centrifugal force is F1 = 205 Newton. As a result, the drive shaft shown in FIG.
F1 = 410 Newton, a belt tension F2 for ensuring a predetermined frictional force between the belt and the roller, and a belt tension F3 for applying a rotational torque are applied. Therefore, since a large load is applied to the drive shaft due to the tension of the belt, it is extremely difficult to use a conventional power transmission device having a pulley and a belt for high-speed rotation. SUMMARY OF THE INVENTION It is an object of the present invention to provide a simple and highly efficient power transmission device while solving an excessive load on a shaft caused by high-speed rotation. According to the present invention, as shown in FIG. 1, a roller 11 and a roller 12 are arranged so that their axes are parallel to each other. The gap H is held to be equal to or slightly larger than the thickness of the thin ribbon-shaped belt 13 reinforced with high-tensile fibers, and the belt 13 is spirally wound around the rollers 11 and 12 through the gap H between the rollers 11 and 12. The belt 13 is wound around the roller 13 from the winding start end a to the winding end b while applying an appropriate tension by the guide roller 14 and the tension roller 15.
And the roller 11 and the roller 12 are connected via a belt 13. According to the present invention, as shown in FIG. 2, the belt tension (F1 + F) required to secure a predetermined frictional force between the belt and the roller while opposing the centrifugal force acting on the belt.
2) works in the opposite direction on the same plane. Therefore, regardless of the magnitude of the tension of the belt, the load on the roller shaft is only the tension F3 for transmitting the rotational torque. A sufficient frictional force can be applied between the belt and the roller by the tension, and the axial load, which is the biggest problem at high speed rotation, can be minimized. Also, by reinforcing with high-tensile fiber, a very thin and light high-tensile belt can be obtained, which can minimize the centrifugal force, air resistance, belt pulsation and vibration acting on the belt moving at high speed. . FIG. 3 and FIG. 4 are a front view and a side view schematically showing a transmission according to an embodiment of the present invention. 3 and 4, reference numeral 21 denotes a hollow case, in which an input shaft 22 and an output shaft 23 whose axes are arranged in parallel are bearings 24, 2 respectively.
4 so as to be rotatable. The input shaft 22 is
Connected to a drive source such as a motor not shown,
The output shaft 23 is connected to a driving object (not shown). Rollers 25 and 26 are fixed to the input shaft 22 and the output shaft 23, respectively.
Reference numerals 5 and 26 are connected via a thin ribbon-like high-tensile belt (hereinafter, referred to as a ribbon belt) 27 reinforced with high-tensile fibers or the like. A gap equal to or slightly larger than the thickness of the ribbon belt 27 is held between the rollers 25 and 26. The rollers 25 and 26 have different diameters according to the gear ratio. In the case of the transmission according to the present embodiment, the input side roller 25 has a large diameter and the output side roller 26 has a small diameter. As shown in FIG. 5, the ribbon belt 27 is formed by applying a high-tensile fiber fiber 28 such as a carbon fiber, a ceramic fiber, or a para-aramid fiber to a film 29 a of a wear-resistant resin such as super-polymerized polyethylene and the high-tensile fiber fiber 28. It is configured such that it is sandwiched between multilayer films 29 to which a thermocompression resin film 29b having thermocompression bonding properties is joined and joined by thermocompression bonding. The ribbon belt 27 is helically wound around the input roller 25 one or more times (in the illustrated example, one turn).
5 is spirally wound around the output roller 26 one or more times (two in the illustrated example) through a gap between the roller 5 and the roller 26, and then is again passed through the gap between the roller 25 and the roller 26. 25, is wound spirally one or more times (one round in the illustrated example), and is wound endlessly from the winding end a of the roller 25 by the guide roller 30 and the tension roller 31 to the winding start end b and wound endlessly. Have been. Ribbon belt 27
Is given an appropriate tension by a tension roller 31. In the transmission shown in FIGS. 3 and 4, when the input shaft 22 is rotated by a drive source (not shown), a roller 25 fixed to the input shaft 22 rotates. Roller 26 by 27
Rotates, and the output shaft 23 rotates with the rotation of the roller 26. As a result, the rotational torque input from the input shaft 22 is applied to the roller 25, the ribbon belt 27, the roller 2
6, and the increased rotational torque is applied to the output shaft 23.
Output from FIGS. 6 and 7 are a front view and a side view schematically showing a transmission using a planetary mechanism according to the embodiment of the present invention. 6 and 7, reference numeral 41 denotes a hollow case. The case 41 is rotatably supported by a track shaft 43 fixed to an external fixing portion 42 via a bearing 44. A cylindrical input shaft 45 is formed integrally with the case 41 so as to be arranged concentrically with the track shaft 43, and an output shaft 46 has a bearing 47 so as to be arranged coaxially with the track shaft 43. It is rotatably supported via The input shaft 45 is connected to a drive source such as a motor (not shown), and the output shaft 46 is connected to a drive target (not shown). A small-diameter orbit roller 48 is fixed to the orbit shaft 43, and a large-diameter sun roller 49 is fixed to the output shaft 46. Case 4
1, intermediate shafts 50 and 51 are respectively mounted on bearings 5 so that the track shaft 43 and the output shaft 46 are arranged in parallel with the shaft center.
It is rotatably supported via two and 52. Intermediate shaft 5
0 and 51 have large-diameter planetary rollers 53.54, respectively.
And the small-diameter planetary rollers 55 and 56 are fixed.
The small-diameter planetary rollers 55 and 56 are connected to a large-diameter sun roller 49 via a ribbon belt 58, respectively. Between the small-diameter orbit roller 48 and the large-diameter planetary roller 53.54, a gap equal to or slightly larger than the thickness of the ribbon belt 57 is held, and the large-diameter sun roller 49 and the small-diameter planetary roller 55, The gaps between 56 are respectively equal to or slightly larger than the thickness of the ribbon belt 58. The structure of the ribbon belts 57 and 58 is the same as that of the ribbon belt 27 shown in FIG. The ribbon belt 57 spirally winds around the large-diameter planetary roller 53.
One or more turns (in the illustrated example), and then one or more turns (in the illustrated example, spirally) around the small-diameter sun roller 48 through the gap between the large-diameter planetary roller 53 and the small-diameter orbital roller 48. (One round), and then spirally one or more rounds (two rounds in the illustrated example) around the large-diameter planetary roller 54 through a gap between the small-diameter orbital roller 48 and the large-diameter planetary roller 54. Then, it is spirally wound around the small-diameter orbit roller 48 one or more times (one round in the illustrated example) again through the gap between the large-diameter planetary roller 54 and the small-diameter sun roller 48, and subsequently the small-diameter orbit. Through the gap between the roller 48 and the large-diameter planetary roller 53, the large-diameter planetary roller 53 is spirally wound one or more rounds (one round in the illustrated example) again, and the guide roller 59.
And the tension roller 60, the large diameter planetary roller 53 is wound from the winding start end a to the winding end b and endlessly wound. An appropriate tension is applied to the ribbon belt 57 by a tension roller 60. The ribbon belt 58 is spirally wound around the large-diameter sun roller 49 for about half a round, and then spirally wound around the small-diameter planetary roller 56 through a gap between the large-diameter sun roller 49 and the small-diameter planetary roller 56. As described above (one round in the illustrated example), the coil is wound around the small-diameter planetary roller 56 and the large-diameter sun roller 49, and then spirally wound once more around the large-diameter sun roller 49 (one round in the illustrated example). 1 round) Wound, followed by a large diameter sun roller 4
9 and the small-diameter planetary roller 55 through a gap between the small-diameter planetary roller 55 and one or more helical turns (in the illustrated example, 1 round).
Lap) and then spirally around the large-diameter sun roller 49 again through one or more laps (1 in the illustrated example) through the gap between the small-diameter planetary roller 55 and the large-diameter sun roller 49.
Circumference), and then spirally around the small-diameter planetary roller 56 one or more times (1 in the illustrated example) again through the gap between the large-diameter sun roller 49 and the small-diameter planetary roller 56.
Circumference) While being wound, the large diameter sun roller 4 is guided by the guide roller 61 and the tension roller 62.
9 and is wound endlessly from a winding start end a to a winding end b. An appropriate tension is applied to the ribbon belt 58 by the tension roller 62. In the transmission shown in FIGS. 6 and 7, when the input shaft 45 is rotated by a drive source (not shown), the case 41 rotates with the rotation of the input shaft 45, and the rotation of the case 41 is changed to the intermediate shaft. 50, 51 to the large-diameter planetary rollers 53, 54, the large-diameter planetary rollers 53, 54
The orbit 54 revolves around the small-diameter orbital roller 48, and the large-diameter planetary rollers 53 and 54 rotate by the small-diameter orbital roller 48 and the ribbon belt 57 along with the orbit. The revolution and rotation of the large-diameter planetary rollers 53 and 54 are performed by the small-diameter planetary rollers 5 via the intermediate shafts 50 and 51.
The small-diameter planetary rollers 55 and 56 revolve and rotate by being transmitted to the small-diameter planetary rollers 55 and 56.
The large-diameter sun roller 49 is rotated by the ribbon belt 58 in accordance with the revolution and rotation of the output shaft 46, and the output shaft 46 is rotated in accordance with the rotation of the large-diameter sun roller 49. As a result, the rotational torque input from the input shaft 45 is increased through the case 41, the small-diameter orbit roller 48, the ribbon belt 57, and the large-diameter planetary rollers 48 and 49, and the increased rotational torque is reduced. Planetary rollers 55 and 56, ribbon belt 5
8. The speed is further increased through the large-diameter sun roller 49, and the further increased rotational torque is output from the output shaft 46. In the embodiment described above, the ribbon roller 57 is attached to the rollers 54, 53 and 48, and the ribbon belt 5 is attached.
8 is wound around the rollers 56, 55 and 49, but two or more ribbon belts are
3, 48 and / or rollers 56, 55, 49. As shown in FIG. 5, the ribbon belts 27, 57, and 58 of the above-described embodiment have a thermocompression bonding property with respect to a film 29a of a wear-resistant resin and a high-tensile fiber fiber 28. High-tensile fiber fibers 28 between multilayer films 29 to which resin films 29b are bonded.
To be joined by thermocompression bonding,
Fibers, yarns or fabrics composed of high-tensile fibers or one or more of them may be bonded to one or more layers by thermocompression bonding or thermocompression bonding and an adhesive. According to the present invention, a plurality of rollers are arranged so that their axes are parallel to each other, and a gap between the rollers is held so as to be equal to or slightly larger than the thickness of the belt. The belt is spirally wound around each roller through the gap between the rollers, and by connecting each roller via the belt, a predetermined frictional force is secured between the belt and the roller while countering the centrifugal force acting on the belt. Because the required belt tension acts in the opposite direction on the same surface, the only load on the roller shaft is the tension for transmitting the rotational torque, regardless of the magnitude of the belt tension, and the belt is spiraled around the roller. By winding one or more turns in a circle, a sufficient frictional force can be applied between the belt and roller with a small belt tension. The shaft load, which is the subject, can be minimized. Also,
By reinforcing the belt with high-tensile fibers, a very thin and light high-tensile belt can be obtained, and the centrifugal force, air resistance, belt pulsation and vibration acting on the belt moving at high speed can be minimized. This makes it possible to increase the rotation speed of a normal motor at a high speed without using a special and expensive spindle motor, and to transmit such high-speed rotation torque. Thus, a highly efficient power transmission device can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a power transmission device of the present invention. FIG. 2 is a side view of the power transmission device of the present invention. FIG. 3 is a front view schematically showing a transmission according to the embodiment of the present invention. FIG. 4 is a side view schematically showing a transmission according to the embodiment of the present invention. FIG. 5 is a schematic view of a ribbon belt. FIG. 6 is a front view schematically showing a transmission using a planetary mechanism according to the embodiment of the present invention. FIG. 7 is a side view schematically showing a transmission using a planetary mechanism according to the embodiment of the present invention. FIG. 8 is a schematic diagram illustrating a prior art powertrain with a representative pulley and belt. [Description of Signs] 11 roller 12 roller 13 belt 14 guide roller 15 tension roller a winding end b winding start

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16H ⁷ /00-7/24 F16G 1/00-9/04

Claims (1)

(57) [Claim 1] A plurality of rollers, a belt, and a winding mechanism for winding the belt are provided, and the plurality of rollers are arranged so that their axes are parallel to each other. The gap between the adjacent rollers is kept equal to or slightly larger than the thickness of the belt, and the belt is spirally wound around each roller through the gap between the adjacent rollers. A power transmission device characterized in that a roller is wound from the winding end to the winding start while being wound endlessly, and a plurality of rollers are connected via a belt.