WO2014073185A1

WO2014073185A1 - Gear device

Info

Publication number: WO2014073185A1
Application number: PCT/JP2013/006429
Authority: WO
Inventors: 和哉古田
Original assignee: ナブテスコ株式会社
Priority date: 2012-11-06
Filing date: 2013-10-30
Publication date: 2014-05-15
Also published as: KR20150083087A; DE112013005300T5; JP2014092249A; CN104769318A

Abstract

A gear device (1) is provided with an outer cylinder (2), a crank shaft (20), a carrier for rotatably supporting the crank shaft (20), and a spur gear (18) joined to the crank shaft (20) by a spline. The spline (40) has a male spline part (41) formed on the crank shaft (20) and a female spline part (42) formed on the inner peripheral surface of an opening (18a) formed on the spur gear (18). The male spline part (41) has an inclined surface (41b) formed between adjacent teeth (41a) at the distal end of the male spline part (41) and inclined further outwards, in the radial direction of the crank shaft (20), with increasing distance towards the distal end of the male spline part (41). The spur gear (18) is constrained, in a state in which the convex part is pressed against the inclined surface (41b), by the crank shaft (20).

Description

Gear device

The present invention relates to a gear device.

Conventionally, a gear device as described in Patent Document 1 is known as a reduction gear that is small and light and can obtain a large reduction ratio. In such a gear device, the rotational driving force of the motor is transmitted to a crankshaft (eccentric body shaft) via a cylindrical input gear (intermediate gear) and a spur gear (transmission gear) meshed therewith. It is rotating.

The above spur gear is connected to the end of the crankshaft by a spline. That is, a male spline portion having a plurality of teeth is formed at the end of the crankshaft, and a female spline portion having a plurality of concave portions corresponding to the teeth is formed on the inner peripheral surface of the opening of the spur gear. ing. By inserting the crankshaft into the opening of the spur gear, the male spline portion and the female spline portion mesh with each other. As a result, the spur gear is restricted from rotating relative to the crankshaft. A pair of retaining rings are attached to both ends of the spur gear in the axial direction of the crankshaft. By these retaining rings, the spur gear is restricted from moving in the axial direction relative to the crankshaft.

In the gear device described in Patent Document 1, the spur gear and the crankshaft are coupled by a spline. The spline coupling portion is designed so that the male spline portion and the female spline portion are engaged by inserting a crankshaft into the opening of the spur gear. For this reason, a slight gap or play in design or manufacturing is allowed in the joint portion by the spline. For this reason, if the gap at the spline coupling portion becomes large due to the combination of the spur gear and the crankshaft, the processing accuracy, or the like, there is a risk that play in the rotational direction of the spur gear will occur.

In the gear device described in Patent Document 1, the movement of the spur gear in the axial direction of the crankshaft is regulated by a pair of retaining rings. For this reason, there is a possibility that backlash in the axial direction of the spur gear may occur due to a design or assembly error.

Due to the play of the spur gear in the rotational direction and the axial direction, there is a possibility that the spline coupling part may be worn with the driving of the gear unit, the gear unit itself may vibrate, and the noise level may increase. .

JP 2010-286098 A

An object of the present invention is to provide a gear device that can reduce wear, vibration, and noise at a joint portion between a spur gear and a crankshaft, and can reduce the number of parts.

A gear device according to one aspect of the present invention is a gear device that transmits power by converting a rotational speed between a pair of counterpart members at a predetermined rotational speed ratio, and an outer cylinder that can be fixed to one counterpart member, and a crankshaft And is configured to be fixed to the other mating member, and is rotatably accommodated inside the outer cylinder, rotatably supports the crankshaft, and is coupled to the outer cylinder in conjunction with the rotation of the crankshaft. A carrier that rotates relative to the crankshaft; and a spur gear coupled to an end of the crankshaft by a spiline. The spline has a male spline portion formed at an end portion of the crankshaft and a female spline portion formed on an inner peripheral surface of the opening of the spur gear. The male spline portion is formed between a plurality of teeth formed at intervals in the circumferential direction of the crankshaft and the back end of the male spline portion and between the teeth. And a slope inclined toward the outside in the radial direction of the crankshaft. The female spline portion includes a plurality of concave portions formed along the inner peripheral surface of the opening of the spur gear, and a convex portion protruding between adjacent teeth of the male spline portion between the concave portions. Have. The spur gear is restrained by the crankshaft in a state where the convex portion is pressed against the slope.

It is sectional drawing of the gear apparatus which concerns on 1st Embodiment of this invention. FIG. 3 is an enlarged cross-sectional view of a coupling portion between a spur gear and a crankshaft in the gear device. It is sectional drawing of the gear apparatus which concerns on 2nd Embodiment of this invention. FIG. 4 is an enlarged cross-sectional view of a coupling portion between a spur gear and a crankshaft in the gear device of FIG. 3.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

(First embodiment)
The gear device 1 according to the first embodiment is a gear device that is applied as a speed reducer to, for example, a swivel unit such as a swivel trunk or arm joint of a robot or a swivel unit of various machine tools. The gear device 1 is a device that converts the rotational speed at a predetermined rotational speed ratio between a base and a revolving body that revolves relative to the base and transmits it in a revolving part of a robot.

As shown in FIG. 1, the gear device 1 of the present embodiment includes an outer cylinder 2, an internal tooth pin 3, a carrier 4, a main bearing 6, a plurality of crankshafts 20, a crank bearing 22, A dynamic gear 24, an input gear (not shown), a plurality of spur gears 18 respectively coupled to the plurality of crankshafts 20, and retaining rings 43 for retaining them provided on the outer sides in the axial direction of the respective spur gears 18. I have.

The outer cylinder 2 has a shape that can be fixed to one counterpart member (for example, the base of a robot), and functions as a case of the gear device 1. The outer cylinder 2 is formed in a substantially cylindrical shape. The outer cylinder 2 is fastened to the base of the robot with bolts or the like. On the inner surface of the outer cylinder 2, a large number of internal tooth pins 3 are arranged at equal intervals in the circumferential direction. The internal tooth pin 3 functions as an internal tooth with which a swing gear 24 made of an external gear meshes. The number of teeth of the oscillating gear 24 is slightly smaller than the number of internal tooth pins 3. In the present embodiment, two (plural) oscillating gears 24 are used.

The carrier 4 has a shape that can be fixed to the other mating member (for example, a rotating body of a robot). The carrier 4 is rotatable relative to the outer cylinder 2 and is accommodated in the outer cylinder 2 in a state of being arranged coaxially with the outer cylinder 2. In the present embodiment, the carrier 4 rotates relative to the outer cylinder 2 around the same axis. The carrier 4 is fastened to the revolving body of the robot with bolts or the like. When the carrier 4 rotates relative to the outer cylinder 2, the revolving body of the robot revolves with respect to the base.

In the present embodiment, an example is shown in which the carrier 4 is fastened to the turning body and turned, and the outer cylinder 2 is fixed to the base and fixed, but the opposite arrangement may be employed. That is, it is of course possible to use the outer cylinder 2 by fastening it to the revolving body and fastening the carrier 4 to the base.

The carrier 4 is supported by a pair of main bearings 6 spaced apart from each other in the axial direction so as to be rotatable relative to the outer cylinder 2. The carrier 4 includes a base portion 32 and an end plate portion 34. Between them, an accommodation space 33 for accommodating a swing gear 24 which is a transmission member for transmitting a rotational force between the outer cylinder 2 and the carrier 4 is formed.

The base portion 32 has a substrate portion 32a disposed in the outer tube 2 in the vicinity of the end portion of the outer tube 2, and a plurality of shaft portions 32b extending in the axial direction from the substrate portion 32a toward the end plate portion 34. . The shaft portion 32 b is fastened to the end plate portion 34 by the bolt 5 while being positioned at a predetermined position facing the end plate portion 34 by the pin 7. Thereby, the base 32 and the end plate part 34 are integrated. Further, a through hole 4 a penetrating in the axial direction is provided at the radial center of the carrier 4. The accommodation space 33 communicates with the outside of the carrier 4 through the through hole 4a.

A plurality of crankshafts 20 (for example, three in this embodiment) are provided, and each crankshaft 20 is arranged at equal intervals (every 120 degrees) in the circumferential direction of the carrier 4. Each crankshaft 20 is rotatably supported by the carrier 4 via a pair of crank bearings 22.

The crankshaft 20 is provided with a plurality (two in this embodiment) of eccentric portions 20a. The plurality of eccentric portions 20 a are arranged so as to be aligned in the axial direction at a position between the pair of crank bearings 22. Each eccentric portion 20a is formed in a columnar shape eccentric from the axis of the crankshaft 20 by a predetermined amount of eccentricity. And each eccentric part 20a is formed in the crankshaft 20 so that it may have a phase difference of a predetermined angle mutually. Note that the number of the eccentric portions 20a may be one.

The plurality of oscillating gears 24 are respectively attached to the eccentric portions 20a of the crankshaft 20 via roller bearings 28a. The oscillating gear 24 is formed to be slightly smaller than the inner diameter of the outer cylinder 2 and meshes with the internal tooth pin 3 on the inner surface of the outer cylinder 2 in conjunction with the eccentric rotation of the eccentric portion 20a when the crankshaft 20 rotates. Oscillates and rotates.

The oscillating gear 24 has a central through hole 24b, a plurality of eccentric part insertion holes 24c, and a plurality of shaft part insertion holes 24d.

The eccentric part insertion holes 24c are provided at equal intervals in the circumferential direction around the central part through hole 24b in the oscillating gear 24. The eccentric portions 20a of the respective crankshafts 20 are inserted into the respective eccentric portion insertion holes 24c with the roller bearings 28a interposed therebetween.

The shaft portion insertion holes 24d are provided at equal intervals in the circumferential direction around the central through hole 24b in the swing gear 24. Each shaft portion insertion hole 24d is disposed at a position between the adjacent eccentric portion insertion holes 24c in the circumferential direction. Each shaft portion 32b of the carrier 4 is inserted into each shaft portion insertion hole 24d with play.

The end of each crankshaft 20 protrudes from the carrier 4 along the axial direction of the carrier 4. A spur gear 18 is spline-coupled to the end of each crankshaft 20 that extends outside the carrier 4. The spur gear 18 is not limited to the configuration located outside the carrier 4. The carrier 4 may be formed with a recess, and the spur gear 18 may be disposed in the recess.

The movement of the spur gear 18 in the rotational direction and the axial direction with respect to the crankshaft 20 is restricted by the biting at the joint portion by the spline 40.

Specifically, as shown in FIG. 2, the spline 40 that couples the spur gear 18 to the crankshaft 20 includes a male spline portion 41 formed at an end protruding from the carrier 4 of the crankshaft 20 and a spur gear. And a female spline portion 42 formed on the inner peripheral surface of the 18 openings 18a.

The male spline part 41 has a plurality of teeth 41 a formed at equal intervals in the circumferential direction of the crankshaft 20. The plurality of teeth 41a need not be formed at regular intervals in the circumferential direction, but may be formed at intervals in the circumferential direction.

Moreover, the male spline part 41 has a slope 41b formed between the teeth 41a adjacent to each other at the back end of the male spline part 41 of the crankshaft 20. The inclined surface 41b is inclined in the direction toward the radially outer side of the crankshaft 20 as it goes to the back of the male spline portion 41 (to the left in FIG. 2).

As the inclined surface 41b, for example, a hob cut-up portion generated when the male spline portion 41 is formed by cutting with a cutting machine having a hob for spline processing is employed. The present invention is not particularly limited with respect to the method of forming the inclined surface 41b, and the inclined surface 41b may be formed by other forming methods.

On the other hand, the female spline portion 42 has a plurality of concave portions 42a formed along the inner peripheral surface of the opening 18a of the spur gear 18. Each recess 42 a is formed at equal intervals along the circumferential direction of the spur gear 18 and has a shape into which the teeth 41 a of the male spline portion 41 can be inserted. The plurality of recesses 42a are not necessarily formed at equal intervals, and may be arranged at intervals according to the interval between adjacent teeth 41a.

Moreover, the female spline part 42b has the convex part 42b which protrudes between the teeth 41a which the crankshaft 20 adjoins between the recessed parts 42a.

In the example shown in FIG. 2, the edge of the opening 18a of the spur gear 18 (that is, the edge of the convex portion 42b) is chamfered, but the present invention is not limited to this, and the chamfering process is not limited to this. It does not have to be applied.

In the above configuration, when the end of the crankshaft 20 is inserted into the opening 18a of the spar gear 18, the male spline portion 41 so that the female spline portion 42 of the spar gear 18 and the male spline portion 41 of the crankshaft 20 are engaged with each other. Teeth 41a are inserted into the recesses 42a of the female spline portion 42. At this time, the convex part 42b between the concave parts 42a of the female spline part 42 is inserted between the teeth 41a and the teeth 41a of the male spline part 41. And the convex part 42a is pressed on the slope 41b formed in the back end of the male spline part 41. FIG. In this state, the wedge effect by the inclined surface 41b, that is, the inclined surface 41b applies a pressing force in the direction toward the radially outer side of the crankshaft 20 to the convex portion 42b, thereby causing friction on the contact surface between the inclined surface 41b and the convex portion 42b. Power increases. As a result, the spur gear 18 bites into the crankshaft 20 and is restrained by the crankshaft 20. Thereby, in the spline 40 that couples the spur gear 18 and the crankshaft 20, the spur gear 18 can be firmly connected to the crankshaft 20 without any backlash in both the rotational direction and the axial direction.

The retaining ring 43 is disposed at a position on the distal end side of the crankshaft 20 with respect to the spur gear 18 in the crankshaft 20. The retaining ring 43 prevents the spar gear 18 from falling off the crankshaft 20. The retaining ring 43 is made of a metal C-shaped member (that is, an arc shape that is not partially closed and closed). The retaining ring 43 is inserted into a ring-shaped groove 20b formed on the outer peripheral surface of the crankshaft 20 after the spur gear 18 is bitten into the inclined surface 41b of the male spline portion 41 of the crankshaft 20 and then the retaining ring 43 is once expanded. It is. At this time, the retaining ring 43 contracts radially inward due to its restoring force, and is firmly fastened to the tip of the crankshaft 20.

The position of the groove 20b is such that when the convex portion 42a is pressed against the inclined surface 41b as described above and the spur gear 18 is disposed at a predetermined position at the end of the crankshaft 20, the retaining ring 43 is placed on the side surface of the spur gear 18. The retaining ring 43 is set at a position where the retaining ring 43 can be fitted into the groove 20b in a state of contact or proximity. Thereby, it can be confirmed that the spur gear 18 is arranged at the end position of the crankshaft 20 depending on whether or not the retaining ring 43 can be fitted into the groove 20b.

The spur gear 18 shown in FIGS. 1 and 2 is a spur gear whose teeth extend parallel to the axial direction. For this reason, when the spar gear 18 meshes with an input gear (not shown) and rotates, the force acting in the axial direction is smaller than that in the case of a bevel gear (bevel gear). Therefore, a large force does not act on the retaining ring 43 in the axial direction during operation.

The plurality of spur gears 18 mesh with input gears (not shown). When a rotational driving force is applied to the input gear from a motor outside the gear device, the rotational driving force is transmitted to each of the plurality of spur gears 18.

Next, the operation of the gear device 1 according to the first embodiment will be described.

Rotational driving force from a motor external to the gear unit 1 is transmitted to each spur gear 18 via an input gear (not shown), whereby each crankshaft 20 rotates about its own axis.

As the crankshaft 20 rotates, the eccentric portion 20a rotates eccentrically. The oscillating gear 24 oscillates and rotates while meshing with the internal tooth pin 3 on the inner surface of the outer cylinder 2 in conjunction with the eccentric rotation of the eccentric portion 20a. The swing rotation of the swing gear 24 is transmitted to the carrier 4 through each crankshaft 20. In this embodiment, since the outer cylinder 2 is fixed to the base 52 and does not move, the carrier 4 and the revolving body 50 rotate relative to the outer cylinder 2 and the base 52 at a rotational speed decelerated from the input rotation. To do.

(Characteristics of the first embodiment)
(1)
In the gear device 1 according to the first embodiment of the present invention, the female spline portion 42 formed in the opening 18a of the spur gear 18 meshes with the male spline portion 41 of the crankshaft 20, and further formed at the back end of the male spline portion 41. The inclined surface 41b is pressed against the convex part 42b of the female spline part 42. In this state, when the inclined surface 41b is strongly pressed against the convex portion 42b, a so-called rust effect is generated in which a large frictional force is generated on the contact surface. For this reason, the spur gear 18 bites into the crankshaft 20 and is restrained by the crankshaft 20. As a result, backlash does not occur in the rotational direction and the axial direction in the spline 40 that is a connecting portion between the spur gear 18 and the crankshaft 20. Therefore, wear, vibration, and noise in the spline connecting portion can be reduced. Further, since it is not necessary to restrain the spar gear 18 by a pair of retaining rings in order to restrict the movement of the spar gear 18 in the axial direction, the number of parts can be reduced.

(2)
Further, in the gear device 1 according to the first embodiment, even when the wedge effect is reduced due to vibration or the like during driving, the spur gear is disposed by the retaining ring 43 disposed on the front end side of the crankshaft 20 with respect to the spur gear 18. It is possible to prevent 18 from falling off the crankshaft 20. Therefore, safety can be improved.

(3)
Further, in the gear device 1 according to the first embodiment, a metal C-shaped retaining ring 43 is used as a retaining member disposed on the distal end side of the crankshaft with respect to the spur gear 18. For this reason, the spur gear 18 can be firmly fastened to the front end portion of the crankshaft 20, and the effect of preventing the spur gear 18 from coming off is further improved.

(Modification of the first embodiment)
(A)
In the gear device 1 of the first embodiment, the retaining ring 43 for preventing the slipping is disposed on the outer side in the axial direction of the spar gear 18, but the present invention is not limited to this, and the retaining ring 43 is not limited thereto. May be omitted. Also in this case, since the female spline portion 42 of the spur gear 18 bites into the inclined surface 41b on the back side of the male spline portion 41 of the crankshaft 18, the gear device 1 is used even when the retaining ring 43 is omitted. Is possible. A retaining ring 43 may be provided to improve safety.

(B)
In the first embodiment, the spur gear 18 is prevented from coming off by one retaining ring 43 in each crankshaft 18, but the present invention is not limited to this, and a plurality of retaining rings 43 are used. May be. When a plurality of retaining rings 43 are used, when the spar gears 18 having different thicknesses are replaced, the plurality of retaining rings 43 are used corresponding to the thickness of the spar gears 18, thereby reducing the width occupied by the retaining rings 43. It is possible to adjust. Therefore, the degree of freedom in selecting parts for the spur gear 18 is expanded. It is also possible to use a shim together with one retaining ring 43 to adjust the width by the shim thickness.

(C)
In the first embodiment, the plurality of crankshafts 20 are arranged around the central through hole 4a (see FIG. 1), but the present invention is not limited to this. For example, a center crank type in which the crankshaft 20 is disposed in the central portion in the radial direction of the carrier 4 may be employed.

(D)
In the first embodiment, the spur gear 18 is inserted into the end portion of the crankshaft 20 that protrudes outward from the end plate portion 34 side of the carrier 4, but the present invention is not limited to this. For example, one end portion of the crankshaft 20 may be configured to protrude outward from the base portion 32 of the carrier 4, and the spur gear 18 may be attached to the end portion.

(Second Embodiment)
In the first embodiment, the crankshaft 20 is disposed at a position on the distal end side of the crankshaft 20 with respect to the spar gear 18 and serves as a retaining member that prevents the spar gear 18 from falling off the crankshaft 20. The gear device 1 using the ring-shaped retaining ring 43 has been described as an example, but the present invention is not limited to this, and other retaining members other than the retaining ring 43 may be employed.

For example, in the gear device 1 shown in FIGS. 3 to 4, an O-ring 45 is used instead of the metal C-shaped retaining ring 43. Other configurations are the same as those in the first embodiment, and a description thereof will be omitted.

The O-ring 45 is a seamless ring-shaped member made of an elastic material such as rubber or resin.

The O-ring 45 is arranged at a position on the crankshaft 20 tip side with respect to the spar gear 18 in the crankshaft 20, similarly to the retaining ring 43, and prevents the spar gear 18 from falling off the crankshaft 20. The O-ring 45 is fitted into the groove 20 b of the crankshaft 20 after the spar gear 18 is bitten into the inclined surface 41 b of the male spline portion 41 of the crankshaft 20. The groove 20b is formed on the outer peripheral surface of the crankshaft 20, and has a ring shape.

(Characteristics of the second embodiment)
(1)
In the gear device 1 according to the second embodiment, the spar gear 18 is cranked by the O-ring 45 disposed on the front end side of the crankshaft 20 with respect to the spar gear 18 even when the wedge effect is reduced by vibration or the like during driving. It is prevented from falling off the shaft 20. Therefore, safety can be improved.

(2)
In the gear device 1 according to the second embodiment, since the O-ring 45 made of an elastic material is used as the retaining member, the retaining member can be easily attached to the crankshaft 20. It becomes easy to cope with automation of assembly.

(Modification of the second embodiment)
In the gear device 1 of the second embodiment, the O-ring 45 for preventing the slipping is disposed outside the spar gear, but the present invention is not limited to this, and the O-ring 45 is not limited thereto. May be omitted. Also in this case, the female spline portion 42 of the spur gear 18 bites into and restrains the slope 41b on the back side of the male spline shaft 41 of the crankshaft 20, so that the gear device 1 is used even when the O-ring 45 is omitted. It is possible. An O-ring 45 may be provided for improving safety.

(Outline of the embodiment)
Here, the embodiment will be outlined.

In the embodiment, the female spline portion formed in the opening of the spur gear meshes with the male spline portion of the crankshaft, and the slope formed at the back end of the male spline portion is pressed against the convex portion of the female spline portion. . In this state, a so-called wedge effect is obtained in which a large frictional force is generated on the contact surface when the inclined surface is strongly pressed against the convex portion. For this reason, the spur gear bites into the crankshaft and is restrained by the crankshaft. As a result, backlash does not occur in the rotational direction and the axial direction at the joint portion between the spur gear and the crankshaft. Therefore, it is possible to reduce wear, vibration, and noise in the joint portion. In addition, since it is not necessary to restrain the spur gear in the axial direction with a pair of retaining rings from both sides of the spur gear, the number of parts can be reduced.

The crankshaft may further include a retaining member that is disposed at a position on a distal end side of the crankshaft with respect to the spurgear and that prevents the spurgear from falling off the crankshaft.

According to such a configuration, even when the wedge effect is reduced due to vibration or the like during driving, the spur gear is prevented from falling off the crankshaft by the retaining member disposed on the front end side of the crankshaft with respect to the spur gear. can do. Therefore, safety can be improved.

The retaining member may be a metal C-shaped retaining ring.

According to such a configuration, it is possible to firmly fasten the crankshaft tip, and the retaining effect is further improved.

Further, the retaining member may be an O-ring made of an elastic material.

According to such a configuration, it becomes easy to attach the retaining member to the crankshaft, and it becomes easy to cope with the automation of the assembly of the gear device.

As described above, according to the embodiment, it is possible to reduce wear, vibration, and noise at the joint portion between the spur gear and the crankshaft. In addition, since a pair of retaining rings for restricting the movement of the spur gear in the axial direction is not necessary, the number of parts can be reduced.

Claims

A gear device that converts the rotational speed between a pair of mating members at a predetermined rotational speed ratio and transmits the gear,
An outer cylinder that can be fixed to one counterpart member;
A crankshaft,
While being configured to be fixable to the other member, it is rotatably accommodated inside the outer cylinder, rotatably supports the crankshaft, and is linked to the outer cylinder in conjunction with the rotation of the crankshaft. A relative rotating carrier;
A spur gear coupled to the end of the crankshaft by a spiline;
With
The spline has a male spline portion formed at the end of the crankshaft, and a female spline portion formed on the inner peripheral surface of the opening of the spur gear,
The male spline portion is formed between a plurality of teeth formed at intervals in the circumferential direction of the crankshaft and the back end of the male spline portion and between the teeth. And a slope inclined toward the outside in the radial direction of the crankshaft as it goes to
The female spline portion includes a plurality of concave portions formed along the inner peripheral surface of the opening of the spur gear, and a convex portion protruding between adjacent teeth of the male spline portion between the concave portions. Have
The spur gear is a gear device that is restrained by the crankshaft in a state where the convex portion is pressed against the slope.
The crank shaft further includes a retaining member that is disposed at a position on a tip side of the crank shaft with respect to the spur gear and prevents the spur gear from falling off the crank shaft.
The gear device according to claim 1.
The retaining member is a metal C-shaped retaining ring.
The gear device according to claim 2.
The retaining member is an O-ring made of an elastic material.
The gear device according to claim 2.