JPH04370442A - Reduction gear - Google Patents

Abstract

PURPOSE:To increase the natural vibration of a drive system containing a reduction gear, to reduce vibration in a normal working area weven when a reduction gear is used for a tool exchange device for an industrial robot and a machining center, and to improve acceleration performance by increasing twist rigidity. CONSTITUTION:An internal tooth comprising pins 39 are formed in the inner periphery of a hub 37. A pinion 33 is provided, at its outer periphery, with an external tooth 33a meshing with the internal tooth, and a plurality of pin holes 33b formed in the inside in an inner peripheral direction. This pinion 33 is engaged with a hub to effect eccentric movement. A through-hole 33c comprising two circular holes is formed between the adjoining pin holes 33b of the pinion 33. A columnar member 38 to which a metal 38a is attached is inserted in a state that it is capable of being in contact with the inner peripheral surface of the circular hole, and automatic movement of the pinion 33 is created.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a reduction gear, and more specifically, the present invention relates to a reduction gear that is attached to a drive device such as a servo motor in industrial robots, automatic tool changers of machining centers, drive devices of crawler vehicles, etc. This is a reducer that achieves a ratio, and has internal teeth on the inner periphery of the hub, external teeth that mesh with the internal teeth on the outer periphery, and a plurality of pin holes arranged inside in the inner periphery direction to achieve eccentric movement. The present invention relates to a speed reducer in which a removable pinion is engaged with the hub, and a plurality of pins are inserted into pin holes of the pinion.

0002

[Prior Art] Japanese Patent Publication No. 64-5176 discloses a reduction gear with a small external size, light weight, and high output, which has a hub provided with internal teeth on the inner periphery, and external teeth on the outer periphery that mesh with the internal teeth. and a pinion having a plurality of pin holes disposed inside the hub in the inner circumferential direction and capable of eccentric movement by engaging with the hub, and a plurality of pins inserted into the pin holes of the pinion to extract rotational motion of the pinion. In the reducer in which a through hole is bored between the pin holes of the pinion, a disc-shaped part and an end disc are disposed on both sides of the pinion, and a columnar part is loosely fitted into the through-hole. The disk-shaped portion and the end disk are integrally connected to form a support block, and both ends of the pin are rotatably supported by the disk-shaped portion and the end disk of the support block. , the plurality of columnar portions of the support block are wide in the circumferential direction on which torsional loads act, and the columnar portions are arranged such that the outermost periphery thereof is located radially outward from the rotation center of the pin. A speed reducer is disclosed.

That is, in the reducer described in the above-mentioned Japanese Patent Publication No. 64-5176, the plurality of columnar parts of the support block are
Since the width is wide in the circumferential direction where torsional loads act, the wide portions in the circumferential direction effectively support the rigidity against the torsional loads caused when torque is generated in the reducer, and the support blocks resist torsional loads. This results in extremely high rigidity. Furthermore, by arranging the outermost periphery of the columnar part of the support block to be located radially outward from the rotation center of the pin that takes out the rotational motion of the pinion, torsional loads on the circumferentially wide part of the columnar part can be reduced. The carrying function can be significantly improved,
Therefore, the external size of the speed reducer can be further reduced, and this speed reducer can output a large output despite its small external size and light weight.

0004

[Problems to be Solved by the Invention] However, in the reducer described in Japanese Patent Publication No. 64-5176, since the plurality of columnar portions of the support block are wide in the circumferential direction, it is difficult to attach the columnar portions to the pinion. A wide hole is formed into which the pinion fits, and the wall thickness between this wide hole and the outer circumference of the pinion becomes thinner, especially in downsized reduction gears. For this reason,
In small, high-output reducers, the torsional rigidity is low due to the reduced wall thickness of the pinion's wide hole, which causes resonance in the low frequency range.
In other words, the natural frequency of the drive system including the reducer is low,
Another problem is that vibrations with large amplitudes occur.

Therefore, when the above-mentioned reduction gear is used in a high-output, small-sized reduction gear such as an industrial robot or a tool changer of a machining center, vibrations of large amplitude occur, especially in the vicinity of the natural frequency of the drive system. There are problems in that the residual vibration is large, and it is not possible to accelerate at high speed, making it impossible to improve acceleration performance.

[0006]

OBJECTS OF THE INVENTION In view of the problems associated with the prior art described above, the present invention aims to increase the natural frequency of the drive system including the reducer by increasing the torsional rigidity of the reducer. The purpose is to reduce vibration in the normal usage range and improve acceleration performance when used in tool changers and the like.

[0007]

[Means for Solving the Problems] The present invention achieves the above object by providing a hub having internal teeth on the inner periphery, external teeth meshing with the internal teeth on the outer periphery, and a plurality of external teeth on the outer periphery in the inner circumferential direction. A pinion is provided with a pin hole and is capable of eccentric movement by engaging with the hub, and a plurality of pins are inserted into the pin hole of the pinion to take out rotational motion of the pinion, and a pin hole is provided between the pin holes of the pinion. In a speed reducer having through holes, the through holes are a plurality of circular holes having centers between adjacent pairs of pin holes, and a cylindrical member is inserted so as to be able to contact the inner peripheral surface of the circular holes. This is achieved by a speed reducer that is characterized by:

[0008]

[Operation] In the present invention, instead of the wide holes that receive the circumferentially wide columnar parts in the reducer disclosed in Japanese Patent Publication No. 64-5176, a plurality of pin holes having a center between each pair of pin holes are provided. Since the circular hole is formed, the pinion's thin part can be eliminated, increasing the rigidity of the pinion. Also,
In the conventional device described above, the torque reaction force from the pinion is received by two or three crank pins due to its structure, but in the device of the present invention, at least when excessive torsional torque is applied to the inner peripheral surface of each circular hole, Since the cylindrical member is inserted in a contactable manner, the cylindrical member partially bears the torque reaction force, thereby further increasing the rigidity. As described above, according to the present invention, by increasing the torsional rigidity of the reducer, the natural frequency of the drive system including the reducer is increased, and when used in industrial robots, tool changing devices of machining centers, etc. It is also possible to reduce vibration in the normal use range and improve acceleration performance. Moreover, the increased stiffness makes the invention more resistant to overloads.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings showing embodiments of the invention. FIG. 1 is a cross-sectional view of an embodiment of the present invention applied to an industrial robot arm, and FIG. 2 is a cross-sectional view taken along line II--II in FIG.

A hydraulic motor (not shown) of a known type is fixed to the frame of the industrial robot, and the rotation of the hydraulic motor is reduced by a reducer 5, and a drive system sprocket (not shown) screwed onto a hub 37 is installed. ) is driven with high output torque. The output shaft of the hydraulic motor 3 is an input rotating shaft of the reducer 5, and is rotatably supported by a pair of bearings (not shown) in the casing of the hydraulic motor.

As shown in FIG. 1, the main body of the support block 13 is in the shape of a disk and has a recess 13a on the back surface that fits tightly into the main body of the hydraulic motor. Further, the support block 13 has a center hole 13b in the center thereof into which the input rotation shaft is inserted. On the surface of the disc-shaped support block 13, a plurality of bearing mounting holes 13c (three in the embodiment) of a predetermined depth are formed equidistantly around the center hole 13b (on an imaginary circle with radius L1). are doing.

Further, as shown in FIG.
The end disk 25 and the support block 13 are integrally connected to the end disk 25 and the support block 13 to constitute the main body of the speed reducer.

Pin receiving member 24 into which the pin 23 is tightly fitted
are implanted between adjacent bearing mounting holes 13c of the support block 13. The distance L2 from the axis of the center hole 13b of the support block 13 to the center axis of the pin receiving member 24 is smaller than the radius L1 of the virtual circle in which the bearing mounting hole 13c exists, and this pin 23 It has sufficient dimensions to withstand the load.

Further, a plurality of cylindrical member mounting holes 13d for supporting the cylindrical member 27 of the present invention (two in the embodiment) are provided between adjacent bearing mounting holes 13c of the support block 13, and a plurality of cylindrical member mounting holes 13d for supporting the cylindrical member 27 of the present invention are provided from the bearing mounting holes 13c. is also radially outward (radius L3
is larger than L1). A bolt attachment hole 13e is formed on the opposite side of the columnar member attachment hole 13d.

In FIG. 1, the end disk 25 includes a support disk 1.
A bearing mounting hole 25a, a bolt through hole 25b, and a pin hole 25c are formed corresponding to the bearing mounting hole 13c, bolt mounting hole 13d, and pin receiving member 24 of No. 3. The support member 13 and the end disk 25 are integrally fastened with bolts 26 via the columnar member 38, and the pin 23 is fitted into the pin receiving member 24 to firmly fix the support member 13 and the end disk 25. There is. A bearing metal 38a is fitted into the cylindrical member 38.

Roller bearings 27 and 29 are installed in the bearing mounting holes 13c and 25a, respectively, and a crank pin 3 is inserted between the bearings 27 and 29 as a pin for taking out the rotational motion of the pinion 33.
1 is rotatably supported at both ends.

The crank pin 31 has two crank parts 31a and 31 eccentrically arranged by a distance e with respect to its rotational axis A.
The crank portions 31a and 31c are fitted into a pin hole 33b of a pinion 33 via a bearing 35.

As shown in FIG. 2, the pinion 33 has a center hole 33d into which the output shaft of a motor (not shown) is inserted.
The crank pin 31 has external teeth 33a having a tooth profile consisting of an equidistant curve to a pericycloid curve on the outer peripheral surface.
A plurality of pin holes 33b (
In the embodiment, three (3) units are provided equidistantly.

Further, a bolt attachment hole 13 is formed in the support block 13 on a circular arc having a constant radius from the center of the pinion 33.
A plurality of circular through holes 33c are provided at positions corresponding to d, that is, between adjacent bearing mounting holes 25a of the end disk 25 and outward in the radial direction from the bearing mounting holes 25a.
In the example, two pieces) are formed.

Referring again to FIG. 1, in this embodiment, ball bearings 36a and 36b are mounted on the outer peripheries of the support block 13 and the end disk 25, and a hub 37 is rotatably supported. The hub 37 drives a drive sprocket (not shown) of the output member, and has a pinion 33 on its inner peripheral surface.
A slightly larger number of small-diameter pins 39 than the number of teeth of the external teeth 33a formed on the outer periphery of the inner teeth are formed by fixed pin gears in an evenly spaced manner. In addition, as shown in Fig. 2, the pinion 3
The through hole 33c of No. 3 and the bearing metal 38a of the cylindrical member 38 are loosely fitted.

[0021] As a result of the rotation of the crank pin 31, the central axes of the crank portions 31a and 31c revolve around the rotation axis of the crank pin 31, and the two pinions 33 are eccentrically rotated, and the external teeth 33a engages with the pin gear of the hub 37. Therefore, pinion 33
The diameter of the through hole 33c is made slightly larger than the sum of the outer diameter of the cylindrical member 38 (metal 38a when a metal is inserted) and the amount of rocking of the pinion, so that at least when a torsional load is applied, the cylindrical member 38 or the outer periphery of the metal 38a contacts the through hole 33c.

Referring again to FIG. 1, in this embodiment, a first external gear (not shown) is integrally fixed to the right end of the input rotating shaft, and the crank pin 3 supported at both ends
A second external gear 43 having a larger number of teeth than the first external gear is fixed to the right end of the second external gear 43, and both gears are meshed with each other. In addition, lids are appropriately fastened to the outside of both gears with bolts in a sealing manner, and an oil seal is provided outside of the bearing 36a that rotatably supports the hub 37 described above to prevent leakage of lubricating oil from the reducer 5. You can.

The rotation of the output shaft of a hydraulic motor or the like, that is, the input rotation shaft of the reducer, is reduced through the first external gear fixed to the input rotation shaft and the second external gear 43 that meshes therewith according to the ratio of the number of teeth of both gears. and transmitted. Due to the rotation of the second external gear 43, the crank portion 31a of the crank pin 31, which is rotatably supported at both ends by the support block 13, rotates, and the pinion 33 is rotated through the bearing 35 so that the pin hole 33b is connected to the crank portion 31.
a, the crank portion 31a undergoes eccentric revolution due to the revolution. At this time, the plurality of crank pins 31 function so that only the rotational motion component of the orbital motion component and the rotational motion component of the pinion 33 is taken out to the hub 37. Therefore, due to the eccentric revolution of the pinion 33, the external teeth 33a formed on the outer periphery of the pinion engage with the pin gear formed on the inner periphery of the hub 37, causing the hub 37 to rotate at a reduced speed. Thus, the drive system is driven by the sprocket attached to the hub 37.

In the embodiment described above, the crank pin 3
An embodiment has been described in which the pinion 33 has three 1's, six cylindrical members 38 and three pins 23, and has corresponding pin holes 33b and circular holes 33c. The present invention can also be applied to reduction gears in which the number of crank pins 31 is other than three.

In the above embodiment, the support block 13 of the reducer
Although the support block is separate from the casing of the hydraulic motor, the present invention can also be applied to a reduction gear in which the support block is provided separately from the casing of the motor. It is also possible to use an electric motor or a pneumatic motor instead of the hydraulic motor in the above embodiment.

In the above embodiment, the output torque is taken out from the hub 37 of the reducer, but in the reduction gear of the present invention, the hub 37 is fixed so that the output is taken out from the support block provided on the same axis as the input rotating shaft. It is also possible.

[0027]

[Effects of the Invention] In the present invention, a plurality of circular holes having a center between each pair of pin holes are formed in place of a wide hole that receives a circumferentially wide columnar part in a conventional speed reducer. Therefore, the thin wall portion of the pinion can be eliminated, and the rigidity of the pinion is increased. Furthermore, since a cylindrical member is inserted into the inner circumferential surface of each circular hole so as to be able to come into contact at least when an excessive torsional torque is applied, in the present invention, the cylinder partially bears the torque reaction force, thereby further increasing the rigidity. Therefore, according to the present invention, by increasing the torsional rigidity of the reducer, it becomes resistant to overload, and the natural frequency of the drive system including the reducer is increased, thereby making it possible to improve the torsional rigidity of the reducer. When used in other applications, it is possible to reduce vibration in the normal use range and improve acceleration performance.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an embodiment of the invention.

FIG. 2 is a sectional view taken along line II-II in FIG. 1, and the sprocket and its mounting bolts are omitted in the figure.

[Explanation of symbols]

5　Reducer 13 Support block 13b Center hole 13c Bearing mounting hole 13d Bolt installation hole 24 Pin receiving member 29 Bearing 31 Crank pin 33 Pinion 33a External teeth 33b pin hole 36a Bearing 36b Bearing 37 Hub 38 Cylindrical member 38a metal 39 pin

Claims (1)

[Claims] 1. A hub having internal teeth provided on the inner periphery, external teeth meshing with the internal teeth on the outer periphery, and a plurality of pin holes arranged inside in the inner periphery direction, the hub being engaged with the hub. In a reducer comprising a pinion capable of eccentric movement, a plurality of pins inserted into pin holes of the pinion to take out rotational motion of the pinion, and a through hole bored between the pin holes of the pinion, the through hole is A speed reducer characterized in that the holes are a plurality of circular holes whose centers are between adjacent pairs of pin holes, and a cylindrical member is inserted so as to be able to come into contact with the inner peripheral surface of the circular holes.