JP3166057B2 - Coaxial speed reducer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coaxial reduction gear used for a robot or the like.

[0002]

2. Description of the Related Art Conventionally, as a coaxial type speed reducer used for driving precision equipment such as a robot, a harmonic drive type speed reducer and a cyclo speed reducer are known.

[0003]

The above conventional coaxial type speed reducers all use a planetary gear mechanism.
A large space cannot be secured around the central axis of the reduction gear. When such a speed reducer is used for driving the joints of the robot, even if a part of the wiring piping members to the front of the joints can be disposed through the inside of the reduction gear, most of the wiring piping members are located outside. There is a problem that it is necessary to dispose it, and its handling becomes troublesome in order to avoid interference with other members of the wiring piping member. SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide a coaxial type speed reducer that can secure a large space around a central axis by using a mechanism completely different from a planetary gear mechanism.

[0004]

In order to achieve the above object,
The present invention provides a cylindrical support member, a ring-shaped input member pivotally supported by the support member, a ring-shaped output member axially separated from the input member and axially supported by the support member, an input member, and an output member. A plurality of inner and outer cylindrical intermediate members arranged between the member and the support member so as to be prevented from rotating with respect to the support member and movably in the axial direction,
An input cam tooth and an output cam tooth are formed at an input member side edge and an output member side edge of each intermediate member at a gear ratio corresponding to a reduction ratio, respectively, and all or a part of the plurality of intermediate members are formed. Are laminated with a phase difference such that the cam teeth of each intermediate member are circumferentially shifted with respect to the cam teeth of the other intermediate members, and the input member cooperates with the input cam teeth of each intermediate member. A drive element extending in the stacking direction of the plurality of intermediate members is provided, which converts the rotational movement of the input member into the axial movement of each intermediate member.
The output member includes a follower extending in the stacking direction of the plurality of intermediate members, which cooperates with the output cam teeth of each intermediate member to convert the axial movement of each intermediate member into the rotational movement of the output member. It is characterized by.

[0005]

The number of teeth of the input cam teeth is a, and the number of teeth of the output cam teeth is b.
The operation of the present invention will be described as follows. In this case, the pitch angle Pin of the input cam teeth is 360 ° / a, and the pitch angle P of the output cam teeth.
out becomes 360 ° / b, and when the driver moves from the tooth valley to the tooth ridge of the input cam tooth by the rotation of Pin / 2 of the input member,
The intermediate member moves forward once to the output member side, and is pushed by the output cam teeth, so that the follower moves from the tooth ridges to the tooth valleys of the output cam teeth, and the input member rotates by Pout / 2. Then, the plurality of intermediate members stacked with a phase difference move forward one after another, and the input member is continuously rotated. In addition, Pout /
When the follower moves from the tooth valley to the tooth ridge of the output cam tooth of the intermediate member by the rotation of 2, the intermediate member is moved back to the input member side, and during that time the input member rotates by Pin / 2 and is driven. The child moves from the tooth ridge of the input cam tooth of the intermediate member to the tooth valley, and the intermediate member moves forward again to the output member by the next rotation of Pin / 2 for the input member, and the rotation of the input member is continuous. And transmitted to the output member. Then, the ratio between the rotation angle of the input member and the rotation angle of the output member is Pin: Pout = 1 / a: 1 / b, and the reduction ratio (input / output) is b / a.

Here, the input member, the output member, and the intermediate member may be provided on either the inner periphery or the outer periphery of the support member, provided that these three members are provided on the same peripheral surface side.
In any case, a large space can be secured around the central axis of the speed reducer.

Incidentally, since the outer intermediate member has a longer circumferential length than the inner intermediate member, the input / output cam teeth formed on the outer intermediate member are circumferentially smaller than the input / output cam teeth formed on the inner intermediate member. When the driver and the follower are formed so as to extend at the same diameter in the laminating direction of the intermediate members, the engagement of the intermediate member inside the driver and the follower with each cam tooth is performed. A mechanically congruent relationship between the state and the engagement state of the outer intermediate member with each of the cam teeth cannot be ensured, and the output member slightly fluctuates in rotation. Therefore, the driver and the follower are extended in the stacking direction of the intermediate member with a diameter difference corresponding to the peripheral length difference of the intermediate member. It is desirable to make the members mechanically congruent.

In this case, the driver and the follower may be formed in a stepped shape in which a diameter difference is provided stepwise for each intermediate member, but at least one of the driver and the follower is connected continuously. It is preferable that the movable member is formed of a tapered movable member having a diameter difference and movable in the stacking direction of the intermediate member, and an adjusting means for adjusting the position of the movable member in the stacking direction of the intermediate member is provided. That is, if the tapered movable member is pushed inward in the stacking direction of the intermediate member, the larger diameter portion of the movable member comes into contact with the corresponding cam teeth of each intermediate member, and the intermediate member is preloaded in the axial direction. Therefore, the backlash of the speed reducer can be easily adjusted by adjusting the position of the movable member.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2, reference numeral 1 denotes a cylindrical support member, on the outer periphery of the support member 1, an input member 2 formed in a ring shape and an output member formed in the same ring shape. 3 with the bearings 2a and 3a respectively separated from each other in the axial direction.
A plurality of inner and outer cylindrical intermediate members 4 are stacked and arranged between the input member 2 and the output member 3 while being held between the input member 2 and the output member 3, and a holding ring surrounding the stacked portion of the intermediate members 4. 5 was fixed to the support member 1 via a plurality of spacers 5a in the circumferential direction.

A plurality of guide blocks 6 having a pair of guide rollers 6a, 6a mounted on both sides in the circumferential direction are provided alternately with the spacers 5a between the support member 1 and the press ring 5. 4, an escape hole 4a for receiving each spacer 5a with an axial gap as shown in FIG.
A guide hole 4b for receiving each guide block 6 with a gap in the axial direction is opened, and a pair of guide rollers 6a, 6a are brought into contact with both circumferential edges of the guide hole 4b, so that each intermediate member 4 is fixed. The support member 1 was supported so as to be able to move in the axial direction by preventing rotation.

Also, two input cam teeth 7 are formed at an edge of the intermediate member 4 on the input member 2 side at a pitch angle of 180 °, and a 9 ° pitch is formed on the edge of the output member 3 side. 4 at the corner
Zero output cam teeth 8 were formed. And the input member 2
And a driver 9 composed of a rotatable roller extending in the stacking direction of the intermediate member 4, that is, the radial direction of the support member 1, and extending to the output member 3 in the radial direction of the support member 1. A follower 10 composed of a pin and a pin was attached, and the driver 9 and the follower 10 were engaged with the input cam teeth 7 and the output cam teeth 8, respectively.

The plurality of intermediate members 4 are stacked with a phase difference so that the input / output cam teeth 7 and 8 of each intermediate member 4 are circumferentially shifted with respect to the input / output cam teeth of the other intermediate members. I have.

The operating principle of the coaxial type speed reducer constructed as described above will be described with reference to FIG. FIG. 4 shows a case where three intermediate members A, B, and C are stacked with a phase difference of 1/3 of the pitch angle Pin of the input cam teeth 7 for simplification. When the input member rotates from the state shown in FIG. 4A in which the driver 9 contacts the tooth valleys of the input cam teeth 7 of the intermediate member 4 of FIG. 4A, the driver 9 rotates as shown in FIG. )
As shown, the intermediate member 4 reaches the forward end position on the output member side by matching the tooth ridges of the input cam teeth 7 of the intermediate member 4 of B. 4 input cam teeth 7
The intermediate member 4 of A starts to move forward to the output member side, and the follower 10 is pushed in the circumferential direction by the output cam teeth 8 of the intermediate member 4 of B and A. Output member 4
Is rotated. At this time, the C intermediate member 4 is returning to the input member side by the axial pressing force acting via the follower 10 with the output cam teeth 8.

When the input member further rotates from the state shown in FIG. 4B, the intermediate member 4 of A continuously moves toward the output member by the axial pressing force acting on the input cam teeth 7 via the driver 9. And the output member is continuously rotated by the circumferential pressing force acting on the follower 10 via the output cam teeth 8 of the intermediate member 4, while the intermediate member 4 of B is driven by the output cam teeth 8 Starts to be moved back to the input member side by the axial pressing force acting via. Then, when the input member rotates by Pin / 6 from the state shown in FIG. 4B, the follower 10 matches the tooth of the output cam tooth 8 of the intermediate member 4 of C as shown in FIG. Thus, the intermediate member 4 returns to the return end position on the input member side, and at the same time, the driver 9 coincides with the tooth valley of the input cam teeth 4 of the intermediate member 4. This state is substantially the same as the state shown in FIG. 4A in which the driver 9 matches the tooth valley of the input cam tooth 4 of the intermediate member 4 of A.

When the input member further rotates from the state shown in FIG. 4C, the intermediate member 4 moves forward to the output member side by the axial pressing force acting on the input cam teeth 7 via the driver 9. Then, the output member is continuously rotated by the circumferential pressing force acting on the follower 10 via the output cam teeth 8 of the intermediate member 4 between A and C. Then, the input member is moved from the state shown in FIG.
After the rotation by Pin / 6, as shown in FIG. 4D, the driver 9 moves to the tooth ridge of the input cam tooth 7 of the intermediate member 4 of A, and the intermediate member 4 reaches the forward end position. This state is substantially the same as the state shown in FIG. 4B in which the driver 9 matches the tooth ridge of the intermediate member 4 of B, and the output member rotates continuously by repeating the above operation.

Then, from the state shown in FIG.
(D) When the input member rotates Pin / 2 minutes in the state shown,
The output member rotates by 1/2 of the pitch angle Pout of the output cam teeth 8, and the reduction ratio (input / output) becomes Pin / Pout. FIG.
In the embodiment shown in FIG. 3 to FIG.
Is 9 °, so the reduction ratio is 20.

The conditions necessary to obtain the proportional constant velocity of the output member 3 with respect to the input member 2 are that the tooth height of the input cam teeth 7 and the tooth height of the output cam teeth 8 are equal to each other. The center trajectory of the driver 9 with respect to the input cam teeth 7 corresponds to the output cam teeth 8
The two cam teeth 7 and 8 are arranged so that the center trajectory of the follower 10 is extended in the circumferential direction by the reduction ratio.
Is to set the shape of. As long as these two conditions are satisfied, the cam teeth 7 and 8 are not limited to the trochoid tooth profile or the like. In the illustrated embodiment, the intermediate member 4
In order to reduce the maximum acceleration of the reciprocating motion, the input cam teeth 7 are formed in an arc tooth shape in which elliptical arcs having different long diameters are combined.

Incidentally, a thrust force acts on the input member 2 and the output member 3 as a reaction force of the reciprocating motion of the intermediate member 4, so that the bearings 2a, 3a supporting the input / output members 2, 3 are supported. Is desirably constituted by one capable of receiving a thrust force, for example, a four-point support bearing such as a cross roller bearing.

The pitch angle of each of the cam teeth 7 and 8 is the same in any of the intermediate members 4. However, the outer periphery of the plurality of stacked intermediate members 4 has a longer peripheral length.
The circumferential pitch length of each of the cam teeth 7 and 8 becomes longer toward the outer intermediate member 4. Therefore, in the illustrated embodiment, the driver 9 and the follower 10 are arranged so that the engagement state of the driver 9 and the follower 10 with the respective cam teeth 7 and 8 becomes mechanically congruent with any intermediate member 4. Are extended in the stacking direction of the intermediate member 4 with a difference in diameter corresponding to the difference in the circumferential length of the intermediate member 4. In this case, the driver 9 and the follower 10 may be formed in a stepped shape in which a diameter difference is provided stepwise for each intermediate member 4, but in the embodiment, the driver 9 and the follower 10 Was formed into a tapered shape having a continuous diameter difference, that is, a conical shape having a term point on the central axis of the support member 1.

Furthermore, in the embodiment, the follower 10 is slidably supported in the laminating direction of the intermediate member 4 along the tapered groove 3b formed on the inner end face in the axial direction of the output member 3, and An adjusting means 11 for adjusting the position of the intermediate member 4 in the stacking direction of the intermediate member 4 is provided. The adjusting means 11 includes an axially inclined wedge ring 11 a abutting on the outer end of the follower 10.
And an adjusting screw 11b screwed into the output member 3 to press the wedge ring 11a in the axial direction, and a return spring 11c abutting on the inner end of the follower 10.

Thus, the wedge ring 1 is adjusted by the adjusting screw 11b.
1a is pushed inward in the axial direction, the follower 10 is pushed inward in the stacking direction of the intermediate member 4 against the return spring 11c, and the larger diameter portion of the follower 10 Each intermediate member 4 is pre-loaded in the axial direction by contacting the output cam teeth 8 of the fourth.
Therefore, the backlash of the speed reducer can be easily adjusted by adjusting the position of the follower 10 by the adjusting means 11.

In the above embodiment, two drivers 9 and 40 followers 10 are provided in accordance with the number of the cam teeth 7 and 8, respectively. , Each cam tooth 7,
8 can be set arbitrarily within the range of the number of teeth or less. The number of the intermediate members 4 is at least three for smooth power transmission. However, when four or more intermediate members are provided, the three intermediate members are placed in the order of Pin / 3 each other as shown in FIG. If there is a difference,
The remaining intermediate members may be provided in the same phase as each of the three intermediate members.

In the above embodiment, the input member 2, the output member 3, and the intermediate member 4 are arranged on the outer periphery of the support member 1 (hereinafter referred to as an inner ring support type), but the embodiment shown in FIG. As in the example, a type in which the input member 2, the output member 3, and the intermediate member 4 are arranged on the inner periphery of the support member 1 (hereinafter, referred to as an outer ring support type) may be used. Incidentally, the input member 2 of this embodiment,
Although the structures of the output member 3 and the intermediate member 4 are not particularly different from those of the above embodiment, the structure of the adjusting means 11 is partially changed, and this point will be described. In this embodiment, as shown in FIG. 6, a wedge ring 11a of the adjusting means 11 is fitted to an inner race of a bearing 11d provided in the support member 1. The eccentric bush 11e attached to a plurality of locations around the abutment 1 was brought into contact with the elastic seal ring 11f provided in the support member 1 at the other end of the outer race. According to this, when the eccentric bush 11e is rotated by loosening its fixing screw 11g, the wedge ring 11a is displaced in the axial direction via the bearing 11d, and the tapered follower 10 is moved in the stacking direction of the intermediate member 4 in the laminating direction. Displacement adjusts backlash. In this case, the driver 9 is formed in a stepped shape.

In both the inner ring support type and the outer ring support type, a wide space can be secured around the central axis of the speed reducer, and the wiring and piping members can be provided through this space. In this case, it is desirable that the motor combined with the speed reducer is also cylindrical. FIGS. 7 to 9 show an embodiment in which the speed reducer and the cylindrical motor 12 are combined.

FIG. 7 shows a cylindrical motor 12 with an outer ring supporting type reduction gear.
And the outer case 12a of the motor 12
Is connected to the support member 1, and the cylindrical rotor 12 of the motor 12 is
b is connected to the input member 2.

FIG. 8 shows a cylindrical motor 12 with an inner ring support type reduction gear.
The support member 1 is extended in the axial direction,
The extension forms the inner case of the motor 12, and the tail end of the outer case 12 a of the motor 12 is fixed to the tip of the extension, and the cylindrical rotor 12 b is connected to the input member 2.

FIG. 9 shows a cylindrical motor 12 with an inner ring supporting reduction gear.
In this embodiment, the supporting member 1 is also used as an outer case of the motor 12, the motor 12 is mounted inside the supporting member 1, and the cylindrical rotor 12b is connected to a flange 12c at one end thereof. And is connected to the input member 2 via the. In the case of this embodiment, the degree of utilization of the hollow portion as the wiring and piping space is somewhat reduced, but the axial space efficiency when combined with the motor 12 can be optimized.

[0028]

As is apparent from the above description, according to the present invention, a large space can be secured around the central axis of the speed reducer, and the inside of the speed reducer can be used as a space for wiring piping members and a space for motors. Can be used effectively.

[Brief description of the drawings]

FIG. 1 is a cutaway side view of a first embodiment of a speed reducer of the present invention.

FIG. 2 is a sectional view taken along the line II-II of FIG.

FIG. 3 is a development view of the intermediate member.

4 (a) to 4 (d) are diagrams showing a rotation transmitting action from a driver to a follower.

FIG. 5 is a cutaway side view of a second embodiment of the speed reducer of the present invention.

FIG. 6 is an enlarged cut-away side view of the adjusting means of the second embodiment.

FIG. 7 is a cut-away side view showing a combined state of a speed reducer and a motor.

FIG. 8 is a cut-away side view showing another embodiment of the combination state of the reduction gear and the motor.

FIG. 9 is a cutaway side view showing still another embodiment of the combination state of the reduction gear and the motor.

[Explanation of symbols]

Reference Signs List 1 support member, 2 input member, 3 output member 4 intermediate member, 7 input cam teeth, 8 output cam teeth 9 driver, 10 follower, 11 adjusting means

Claims (5)

(57) [Claims] A cylindrical support member, a ring-shaped input member pivotally supported by the support member, a ring-shaped output member axially spaced from the input member and supported by the support member, and an input member. A plurality of inner and outer cylindrical intermediate members arranged between the output member and the support member so as to be rotatable with respect to the support member and movably in the axial direction, and the input member side edge and the output member side end of each intermediate member. The input cam teeth and the output cam teeth are formed on the edge and the tooth number ratio corresponding to the reduction ratio, respectively, and all or a part of the plurality of intermediate members are formed by the cam teeth of each intermediate member. Laminated with a phase difference so as to shift in the circumferential direction with respect to the cam teeth, and the input member converts the rotational motion of the input member into the axial motion of each intermediate member in cooperation with the input cam teeth of each intermediate member In addition to providing a driver extending in the stacking direction of a plurality of intermediate members, A coaxial shaft provided with a follower extending in the stacking direction of the plurality of intermediate members, for converting axial movement of each intermediate member into rotational movement of the output member in cooperation with the output cam teeth of the intermediate member. Type reducer. 2. The coaxial reduction gear according to claim 1, wherein the input member, the output member, and the intermediate member are arranged on the outer periphery of the support member. 3. The coaxial reduction gear according to claim 1, wherein the input member, the output member, and the intermediate member are arranged on an inner periphery of the support member. 4. The driving device according to claim 1, wherein the driving element and the driven element are extended in a stacking direction of the plurality of intermediate members with a diameter difference corresponding to a circumferential length difference of the intermediate members. The coaxial type speed reducer according to any one of the preceding claims. 5. A method according to claim 1, wherein at least one of the driver and the follower is
It is characterized by comprising a tapered movable member having a continuous diameter difference and movable in the laminating direction of the intermediate member, and an adjusting means for adjusting the position of the movable member in the laminating direction of the intermediate member is provided. Item 5. A coaxial type speed reducer according to item 4.