KR20150083087A - Gear device - Google Patents

Abstract

The gear device 1 includes an outer cylinder 2, a crankshaft 20, a carrier 4 for rotatably supporting the crankshaft 20, and a spur gear 20 connected to the crankshaft 20 by a spline, (18). The spline 40 has a male type spline portion 41 formed on the crankshaft 20 and a female type spline portion 42 formed on the inner circumferential surface of the opening 18a of the spur gear 18. The male spline portion 41 is formed between the adjacent teeth 41a at the inner side end of the male spline portion 41 and extends in the radial direction of the crankshaft 20 toward the inner side of the male spline portion 41 And an inclined surface 41b inclined in a direction toward the outside. The spur gear 18 is restrained by the crankshaft 20 in a state in which the convex portion is pressed against the inclined surface 41b.

Description

GEAR DEVICE

The present invention relates to a gear device.

BACKGROUND ART [0002] Conventionally, a gear device as disclosed in Patent Document 1 is known as a speed reducer that is small and lightweight and achieves a large reduction ratio. In such a gear device, the rotational driving force of the motor is transmitted to a crankshaft (eccentric body shaft) through a cylindrical input gear (intermediate gear) and a spur gear (transmission gear) engaged therewith, and the crankshaft is rotated .

The above spur gear is coupled to the end of the crankshaft by a spline. That is, a male spline portion having a plurality of teeth is formed at an end of the crankshaft, and a female spline portion having a plurality of recesses corresponding to the corresponding shape is formed in the inner peripheral surface of the opening of the spur gear. By inserting the crankshaft into the opening of the spur gear, these male and female spline portions engage with each other. Thereby, the spur gear is regulated not to rotate relative to the crankshaft. A pair of retaining rings are mounted on both ends of the spur gear in the axial direction of the crankshaft. By these retaining rings, the spur gear is regulated not to move 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. In the coupling portion by the spline, the male type spline portion and the female type spline portion are designed to engage by inserting the crankshaft into the opening of the spur gear. For this reason, in the joint portion by this spline, a slight gap or clearance in design or manufacturing is allowed. As a result, if the clearance in the spline coupling portion becomes large due to the combination of the spur gear and the crankshaft, the processing accuracy, or the like, the rumble may occur in the rotational direction of the spur gear.

In the gear device described in Patent Document 1, the pair of retaining rings restrict the movement of the spur gear in the axial direction of the crankshaft. This may cause rattling in the axial direction of the spur gear due to design or assembly errors.

The influence of the rattling generated in the rotational direction and the axial direction of the spur gear causes wear on the spline coupling portion as the gear device is driven and vibration occurs in the gear device itself or the noise level is increased There is a concern.

Japanese Patent Application Laid-Open No. 2010-286098

An object of the present invention is to provide a gear device capable of reducing abrasion, vibration and noise at a joint portion between a spur gear and a crankshaft, and reducing the number of parts.

A gear device according to an aspect of the present invention is a gear device that transmits and rotates a rotational speed ratio between a pair of counterpart members at a predetermined rotational speed ratio and includes an outer cylinder fixed to one of the mating members, A carrier rotatably supported in the outer cylinder and rotatably supporting the crankshaft and relatively rotating with the outer cylinder in conjunction with rotation of the crankshaft; And a spur gear coupled to the end portion by a spline. The spline has a male spline formed at an end of the crankshaft and a female spline formed at an inner circumferential surface of the opening of the spur gear. Wherein said male spline portion is formed between a plurality of said male spline portions spaced apart in the circumferential direction of said crankshaft and an inner end portion of said male spline portion and formed between said male spline portion and said male spline portion in a radially outward direction of said crankshaft toward the inner side of said male spline portion It has a sloped slope. The female type spline portion has a plurality of recesses formed along the inner circumferential surface of the opening of the spur gear and a convex portion protruding between adjacent recesses of the male spline portion between the recesses. And the spur gear is restrained to the crankshaft in a state in which the convex portion is pressed against the inclined surface.

1 is a sectional view of a gear device according to a first embodiment of the present invention.
2 is an enlarged cross-sectional view showing a coupling portion between the spur gear and the crankshaft in the gear device.
3 is a cross-sectional view of a gear device according to a second embodiment of the present invention.
Fig. 4 is an enlarged cross-sectional view showing a coupling portion between the spur gear and the 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, for example, a gear device applied to a turning part such as a turning body of a robot, a turning part such as an arm joint, or a turning part of various machine tools as a speed reducer. The gear device 1 is a device for converting the rotational speed between a base and a revolving body relatively rotating with respect to the base to convert the rotational speed to a predetermined rotation ratio.

1, the gear device 1 of the present embodiment includes an outer cylinder 2, an inner gear pin 3, a carrier 4, a main bearing 6, a plurality of crankshafts 6, (Not shown), a plurality of spur gears 18 coupled to the plurality of crankshafts 20, and a plurality of spur gears 20 connected to the spur gears 20. The spur gears 20, the crankshaft 22, the rocking gear 24, And a retaining ring 43 provided on the outer side of the gear 18 in the axial direction.

The outer cylinder 2 has a shape that can be fixed to one of the mating members (for example, the base of the 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 by bolts or the like. On the inner surface of the outer cylinder 2, a plurality of inner gear pins 3 are arranged at regular intervals in the circumferential direction. The inner gear pin (3) functions as an inner gear to which the rocking gear (24), which is a shout gear, is engaged. The number of teeth of the rocking gear 24 is slightly smaller than the number of the inner gear pins 3. [ In the present embodiment, two (plural) swing gears 24 are used.

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

In the present embodiment, an example is shown in which the carrier 4 is fastened to the slewing body to make a turn, and the outer cylinder 2 is fixed to the base so as to be floated. However, the opposite arrangement may be employed. That is, it is of course possible to fasten the outer cylinder 2 to the slewing body and fasten the carrier 4 to the base.

The carrier (4) is supported so as to be rotatable relative to the outer cylinder (2) by a pair of main bearings (6) spaced from each other in the axial direction. The carrier 4 is provided with a base portion 32 and an end plate portion 34. A receiving space 33 for accommodating a swinging gear 24 as a transmitting member for transmitting the rotational force between the outer cylinder 2 and the carrier 4 is formed.

The base portion 32 includes a base portion 32a disposed in the vicinity of the end of the outer cylinder 2 in the outer cylinder 2 and a plurality of base portions 32a extending in the axial direction from the base portion 32a toward the end plate portion 34. [ And a shaft portion 32b. The shaft portion 32b is fastened to the end plate portion 34 by the bolts 5 in a state where the shaft portion 32b is positioned at a predetermined position facing the end plate portion 34 by the pin 7. Thereby, the base portion 32 and the end plate portion 34 are integrated. In the radial direction central portion of the carrier 4, a through hole 4a penetrating in the axial direction is formed. The accommodation space 33 communicates with the outside of the carrier 4 through the through hole 4a.

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

The crankshaft 20 is provided with a plurality of (two in this embodiment) eccentric portions 20a. The plurality of eccentric portions 20a are arranged so as to be arranged in the axial direction at positions between the pair of crank bearings 22. [ Each of the eccentric portions 20a is formed in a columnar shape eccentric to a predetermined eccentric amount from the axial center of the crankshaft 20, respectively. The eccentric portions 20a are formed on the crankshaft 20 so as to have a phase difference of a predetermined angle with respect to each other. The number of the eccentric portions 20a may be one.

The plurality of rocking gears 24 are mounted on the respective eccentric portions 20a of the crankshaft 20 via roller bearings 28a. The rocking gear 24 is formed so as to be slightly smaller than the inner diameter of the outer cylinder 2. The inner gear pin of the outer cylinder 2 is engaged with the eccentric rotation of the eccentric portion 20a when the crankshaft 20 rotates, 3).

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

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

The shaft portion insertion through holes 24d are formed at equal intervals in the circumferential direction around the center through hole 24b in the swing gear 24. Each of the shaft portion insertion through holes 24d is disposed at a position between adjacent eccentric portion insertion through holes 24c in the circumferential direction. The respective shaft portion 32b of the carrier 4 is inserted through the respective shaft portion insertion through holes 24d in a state of having a clearance.

The end portions of the respective crankshafts 20 project outwardly from the carrier 4 along the axial direction of the carrier 4. A spur gear 18 is spline-coupled to an end portion of the crankshaft 20 extending to the outside of the carrier 4. Further, the spur gear 18 is not limited to the structure located on the outer side of the carrier 4. The carrier 4 may have a concave portion and the spur gear 18 may be disposed in the concave portion.

The spur gear 18 is restricted from moving in the rotational direction and the axial direction with respect to the crankshaft 20 due to the crushing at the engagement portion by the spline 40. [

2, the spline 40 for coupling the spur gear 18 to the crankshaft 20 is formed on the end portion of the crankshaft 20 projecting outwardly from the carrier 4 Shaped spline portion 41 and a female spline portion 42 formed on the inner peripheral surface of the opening 18a of the spur gear 18. [

The male spline section (41) has a plurality of teeth (41a) formed at equal intervals in the circumferential direction of the crankshaft (20). In addition, the plurality of teeth 41a need not be formed equidistantly in the circumferential direction, but may be formed to be spaced from each other in the circumferential direction.

The male spline portion 41 has an inclined surface 41b formed between the adjacent teeth 41a at the inner side end of the male spline portion 41 of the crankshaft 20. The inclined surface 41b is inclined toward the radially outer side of the crankshaft 20 toward the inside of the male spline portion 41 (toward the left side in Fig. 2).

As the inclined surface 41b, for example, a hob-reared portion generated when the male spline portion 41 is formed by cutting with a cutting machine having a hob for spline processing is employed. Further, the present invention is not particularly limited to the method of forming the inclined face 41b, but the inclined face 41b may be formed by another forming method.

The female spline portion 42 has a plurality of recesses 42a formed along the inner circumferential surface of the opening 18a of the spur gear 18. Each concave portion 42a is formed at equal intervals along the circumferential direction of the spur gear 18 and has a shape into which the teeth 41a of the male spline portion 41 can be inserted. The plurality of concave portions 42a need not be formed at equal intervals but may be arranged at intervals in accordance with the interval between adjacent teeth 41a.

The female spline portion 42b has a convex portion 42b protruding between adjacent teeth 41a of the crankshaft 20 between the concave portions 42a.

2, the rim of the opening 18a of the spur gear 18 (i.e., the rim of the convex portion 42b) is chamfered. However, the present invention is not limited to this, The chamfering may not be performed.

In the above configuration, when the end portion of the crankshaft 20 is inserted into the opening 18a of the spur gear 18, the female spline portion 42 of the spur gear 18 and the male spline portion of the crankshaft 20 The spline 41a of the male spline 41 is inserted into the recess 42a of the female spline 42 so that the female spline 41 engages. At this time, the convex portion 42b between the concave portions 42a of the female type spline portion 42 is inserted between the teeth 41a and 41a of the male type spline portion 41. The convex portion 42a is pressed against the inclined surface 41b formed on the inner side end of the male spline portion 41. [ In this state, the wedge effect by the inclined face 41b, that is, the inclined face 41b, gives a pressing force in the direction toward the radially outer side of the crankshaft 20 to the convex portion 42b, And the convex portion 42b is increased. Thus, the spur gear 18 is attached to the crankshaft 20 and restrained to the crankshaft 20. The spline 40 for coupling the spur gear 18 and the crankshaft 20 can rotate the spur gear 18 to the crankshaft 20 without causing rattling in both the rotating direction and the axial direction ).

The retaining ring 43 is disposed on the crankshaft 20 at a position on the tip side of the crankshaft 20 with respect to the spur gear 18. [ The retaining ring 43 prevents the spur gear 18 from falling off the crankshaft 20. The retaining ring 43 is made of a metal C-shaped member (that is, a part of a circular arc shape in which a part is cut off and not closed on the way). The retaining ring 43 extends the retaining ring 43 once after the spur gear 18 is pushed into the inclined surface 41b of the male spline 41 of the crankshaft 20, Shaped grooves 20b formed on the outer circumferential surface of the base 20. At this time, the retaining ring 43 contracts radially inwardly due to its restoring force and is tightly fastened to the tip end 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 and the spur gear 18 is disposed at a predetermined position of the end portion of the crankshaft 20, The retaining ring 43 is fitted into the groove 20b in a state where the retaining ring 43 is in contact with or close to the side surface of the spur gear 18. [ As a result, it can be confirmed that the spur gear 18 is disposed at the fixed position of the end 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 that extends parallel to the axial direction. As a result, when the spur gear 18 rotates in engagement with the input gear (not shown), the force acting in the axial direction is small as compared with the case of the bevel gear (crown gear). Therefore, a large force does not act in the axial direction with respect to the retaining ring 43 during operation.

The plurality of spur gears 18 are respectively engaged with input gears (not shown). A rotational driving force is imparted to the input gear from a motor outside the gear unit, so that the rotational driving force is transmitted to each of the plurality of spur gears.

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

The rotational driving force from a motor outside the gear device 1 is transmitted to each spur gear 18 through an input gear (not shown), whereby each of the crankshafts 20 rotates around respective axes.

As the crankshaft 20 rotates, the eccentric portion 20a rotates eccentrically. The rocking gear 24 swings and rotates while being engaged with the inner gear pin 3 on the inner surface of the outer cylinder 2 in association with the eccentric rotation of the eccentric portion 20a. The rocking rotation of the rocking gear 24 is transmitted to the carrier 4 through each crankshaft 20. The carrier 4 and the swivel body 50 are fixed to the outer cylinder 2 and the base 52 by the rotation speed reduced from the input rotation, Lt; / RTI >

(Features of First Embodiment)

(One)

The female type spline portion 42 formed in the opening 18a of the spur gear 18 is engaged with the male type spline portion 41 of the crankshaft 20 in the gear device 1 according to the first embodiment of the present invention And the inclined surface 41b formed on the inner side end of the male spline portion 41 is pressed against the convex portion 42b of the female spline portion 42. [ In this state, a so-called wedge effect is obtained in which the inclined face 41b is strongly pressed against the convex portion 42b to generate a large frictional force on the contact face. Thus, the spur gear 18 adheres to the crankshaft 20 and is constrained to the crankshaft 20. As a result, rattling does not occur in both the rotational direction and the axial direction in the spline 40, which is the engagement portion of the spur gear 18 and the crankshaft 20. [ Therefore, wear, vibration, and noise in the spline coupling portion can be reduced. In addition, since it is not necessary to restrain the spur gear 18 by a pair of retaining rings in order to restrict axial movement of the spur gear 18, the number of parts can be reduced.

(2)

In the gear device 1 according to the first embodiment, even when the wedge effect is lowered by vibration or the like during driving, the retaining ring (not shown) disposed on the tip side of the crankshaft 20 with respect to the spur gear 18, It is possible to prevent the spur gear 18 from falling off the crankshaft 20 by the spur gear 43. Therefore, safety can be improved.

(3)

In the gear device 1 according to the first embodiment, a metallic C-shaped retaining ring 43 is used as a slip-off preventing member disposed on the tip end side of the crankshaft with respect to the spur gear 18. [ As a result, the spur gear 18 can be firmly fastened to the tip end portion of the crankshaft 20, and the spur gear 18 can be prevented from slipping off.

(Modification of First Embodiment)

(A)

In the gear device 1 of the first embodiment, the retaining ring 43 is provided on the outer side in the axial direction of the spur gear 18, but the present invention is not limited to this, The inning ring 43 may be omitted. The female spline portion 42 of the spur gear 18 is caught and restrained in the inclined surface 41b on the inner side of the male spline portion 41 of the crankshaft 18, It is possible to use the gear device 1 in a state where the gear device 1 is omitted. In addition, a retaining ring 43 may be provided to improve safety.

(B)

In the first embodiment, the spur gear 18 is prevented from slipping out by one retaining ring 43 in each crankshaft 18. However, the present invention is not limited to this, The retaining ring 43 may be used. When a plurality of retaining rings 43 are used and a plurality of retaining rings 43 are used corresponding to the thickness of the spur gear 18 when the spur gears 18 having different thicknesses are used, It is possible to adjust the width occupied by the inner ring 43. Therefore, the degree of freedom in selecting parts of the spur gear 18 is increased. It is also possible to use the seam together with one retaining ring 43 to adjust the width by the thickness of the core.

(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, the crankshaft 20 may be of the center crank type arranged at the center of the carrier 4 in the radial direction.

(D)

In the first embodiment, the spur gear 18 is inserted into the end portion of the crankshaft 20 protruding outward from the end plate portion 34 side of the carrier 4, but the present invention is not limited to this. One end of the crankshaft 20 may protrude outwardly from the base portion 32 of the carrier 4 and the spur gear 18 may be attached to the end of the crankshaft 20. [

(Second Embodiment)

In the first embodiment, the crankshaft 20 is disposed at the tip end side of the crankshaft 20 with respect to the spur gear 18, and prevents the spur gear 18 from falling off the crankshaft 20 The present invention is not limited to this, but the present invention is not limited to this, and other than the retaining ring 43, other than the retaining ring 43, A slip-off preventing member may be employed.

For example, in the gear device 1 shown in Figs. 3 to 4, an O-ring 45 is used instead of a metal C-shaped retaining ring 43. The other structures are common to those of the first embodiment, and therefore the description thereof is omitted.

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

The O ring 45 is disposed on the crankshaft 20 at a position on the tip end side of the crankshaft 20 with respect to the spur gear 18 as in the retaining ring 43, Thereby preventing it from falling off the shaft 20. The O-ring 45 is inserted into the groove 20b of the crankshaft 20 after the spur gear 18 is inserted into the inclined surface 41b 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.

(Features of the Second Embodiment)

(One)

In the gear device 1 according to the second embodiment, even when the wedge effect is lowered due to vibration or the like during driving, the O-ring 45 disposed on the tip side of the crankshaft 20 with respect to the spur gear 18 Thereby preventing the spur gear 18 from falling off from the crankshaft 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 slip-off prevention member, the slip prevention member can be easily mounted on the crankshaft 20, It becomes easy to cope with the automation of the assembling of the main body 1.

(Modification of Second Embodiment)

In the gear device 1 of the second embodiment, an O-ring 45 for preventing disconnection is disposed outside the spur gear. However, the present invention is not limited to this, and the O- It may be omitted. In this case, too, the female spline portion 42 of the spur gear 18 is engaged with the inclined surface 41b on the inner side of the male spline shaft 41 of the crankshaft 20 so that the O-ring 45 is omitted It is possible to use the gear device 1 even in the state of FIG. Further, an O-ring 45 may be provided for improving safety.

(Overview of Embodiment)

Here, the above embodiment will be schematically described.

In the above embodiment, the female spline portion formed on the opening of the spur gear is engaged with the male spline portion of the crankshaft, and the sloped surface formed on the inner side end portion 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 the inclined surface is strongly pressed against the convex portion, thereby generating a large frictional force on the contact surface. As a result, the spur gear is attached to the crankshaft and restrained to the crankshaft. As a result, rattling does not occur in both the rotational direction and the axial direction in the engagement portion between the spur gear and the crankshaft. Therefore, the abrasion, vibration, and noise in the bonding portion can be reduced. In addition, since it is not necessary to restrain the spur gear from being paired with the pair of retaining rings from both sides of the spur gear in order to regulate the axial movement of the spur gear, the number of parts can be reduced.

The crankshaft may further include a slip-off preventing member which is disposed at a position on the tip side of the crankshaft relative to the spur gear and which prevents the spur gear from falling off from the crankshaft.

With this configuration, even when the wedge effect is lowered due to vibration or the like during driving, the spur gear can be prevented from falling off the crankshaft by the stopper member disposed at the tip side of the crankshaft relative to the spur gear. Therefore, safety can be improved.

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

According to this configuration, it is possible to securely fasten the crankshaft to the leading end thereof, and the slipping-off preventing effect is further improved.

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

According to this configuration, it is easy to mount the stopper member on the crankshaft, and it becomes easy to automate the assembly of the gear device.

INDUSTRIAL APPLICABILITY 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 axial movement of the spur gear is unnecessary, the number of parts can be reduced.

Claims (4)

A gear device for converting rotational speed between a pair of counterpart members at a predetermined rotation ratio,
An outer cylinder which can be fixed to one of the mating members,
A crankshaft,
A carrier rotatably supported in the outer cylinder and rotatably supporting the crankshaft and relatively rotatable with the outer cylinder in conjunction with rotation of the crankshaft;
And a spur gear coupled to an end of the crankshaft by a spline,
Wherein the spline has a male spline formed at an end of the crankshaft and a female spline formed at an inner circumferential surface of the opening of the spur gear,
Wherein said male spline portion is formed between a plurality of said male spline portions spaced apart in the circumferential direction of said crankshaft and an inner end portion of said male spline portion and formed between said male spline portion and said male spline portion in a radially outward direction of said crankshaft toward the inner side of said male spline portion And has a sloped inclined surface,
The female type spline portion has a plurality of recesses formed along the inner circumferential surface of the opening of the spur gear and a convex portion protruding between adjacent recesses of the male spline portion between the recesses,
And the spur gear is constrained to the crankshaft in a state in which the convex portion is pressed against the inclined surface. 2. The crankshaft according to claim 1, further comprising a slip prevention member which is disposed at a position on a tip end side of the crankshaft relative to the spur gear in the crankshaft and prevents the spur gear from falling off from the crankshaft, Device. The gear device according to claim 2, wherein the stop member is a C-shaped retaining ring made of metal. The gear device according to claim 2, wherein the stopper member is an O-ring made of an elastic material.

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