JP5508197B2 - transmission - Google Patents

Description

  The present invention relates to a transmission such as a reduction gear, and more particularly to a structure for preventing grease leakage.

  In a transmission, grease is generally injected into a meshing portion of a gear. In order to prevent the grease from leaking, a ring-shaped oil seal is provided around the rotating shaft.

  Since the gap around the shaft can be closed by the oil seal, grease leakage can be stably prevented. However, since the oil seal is in contact with the shaft, rotation resistance is generated, which is not preferable in terms of mechanical efficiency. In addition, since the oil seal is a relatively expensive part, there is a disadvantage in terms of material cost.

  On the other hand, a transmission having a grease sealing structure that does not use an oil seal has been proposed (Patent Document 1).

  This transmission is provided with a downward projecting shaft 16 and an output shaft 24, a speed change mechanism portion 12 provided between them, a case member 14 for housing them, and the like (reference numerals are based on the same document). The downward projecting shaft 16 projects downward from the case member 14, the output shaft 24 projects upward from the case member 14, and this transmission is installed such that the rotating shaft faces in the vertical direction (vertical installation). The downward projecting shaft 16 is fitted to the output shaft 30a of the motor, and is rotatably supported by the motor bearing together with the output shaft.

  A grease sealing structure 18 is provided at a portion between the case member 14 and the downward projecting shaft 16 in order to prevent the grease falling or scattering from the transmission mechanism portion 12 from flowing out from the lower side of the case member 14. It has been.

  Specifically, a small dimension of about 0.5 mm is set between the case member 14 and the downward projecting shaft 16 (gap portion 32). Adjacent to the gap portion 32, both the case member 14 and the downward projecting shaft 16 are provided with annular portions 34 and 36 projecting upward in a coaxial manner. The annular portion 36 of the downward projecting shaft 16 projects upward from the annular portion 34 of the case member 14.

  Grease reservoirs 38 and 40 are formed in a lower part on the outer peripheral side of the annular part 34 in the case member 14 and a lower part on the inner peripheral side of the annular part 36 in the downward projecting shaft 16, respectively. A slope surface is formed on the upper surface of each of the annular portions 34 and 36 so as to guide the grease to the grease reservoirs 38 and 40. Grease falling from the speed change mechanism 12 is guided and stored in the grease reservoirs 38 and 40 by the annular portions 34 and 36.

  On the other hand, grease is a lubricating oil with semi-solid properties and low fluidity. Grease is a non-Newtonian fluid and its properties change depending on the presence or absence of external force. For example, when the transmission is driven and a shearing force acts on the grease, the grease liquefies and the fluidity increases. When the transmission stops and the shearing force is no longer applied, the grease loses its fluidity and returns to its original semi-solid state.

JP 2002-213621 A

  In the case of the grease sealing structure of Patent Document 1, the transmission is premised on being placed vertically, and therefore lacks versatility. For example, when placed horizontally, the grease reservoirs 38 and 40 are also turned sideways, making it difficult to store grease. In addition, the annular portion 36 is in the way of guiding the grease to the grease reservoir 38. When the grease hardens in the gap between the annular portions 34 and 36 and the carrier 20, it becomes difficult to guide the grease to the grease reservoir 38. Therefore, the grease having reduced fluidity travels through the annular portions 34 and 36 and the gap portion. 32 is likely to enter and may cause grease to flow out. Further, there is a disadvantage that the processing of the annular portion 36 is difficult.

  Accordingly, an object of the present invention is to provide a transmission that has a simple structure but can suppress leakage of grease without using an oil seal and has excellent versatility.

  In order to achieve the above object, in the present invention, grease that leaks from the transmission unit in a state of high fluidity is blown by a centrifugal force into a space recessed around the shaft and solidified there.

  Specifically, the transmission according to the present invention includes a plurality of planets interposed between a first connection portion and a second connection portion that are rotatably supported, and the first connection portion and the second connection portion. The transmission includes a transmission having a gear, and a housing that houses the first connection, the second connection, and the transmission, and grease is injected into the transmission.

  The second connecting portion includes a rotating body that is rotatably supported by the housing via a bearing, and a sun gear that is provided coaxially with the rotating body and engages with the planetary gear. And between the sun gear and the bearing, a first restricting wall portion and a second restricting wall portion projecting from the casing toward the rotating body over the entire circumference are provided apart from each other in the rotation axis direction. ing.

  That is, in this transmission, between the speed change part and the second connecting part is partitioned by the first restriction wall part, and the planetary gear protrudes from the center opening of the first restriction wall part to the speed change part side. And since the 2nd control wall part is provided in the rotation axis direction away from the 1st control wall part, the 1st control wall part and the 2nd control wall part are in the field at the 2nd connection part side of a case. And a space (annular space) that faces the front end portion of the rotating body from the outside in the radial direction is formed. This annular space communicates with the region of the transmission unit through the opening of the first restriction wall.

  When the fluidity is increased by driving the transmission, the grease injected into the transmission unit is likely to leak to the second connecting unit side through the opening. Since the rotating body rotates at a high speed, the grease leaking through the rotating body is blown into the annular space by the centrifugal force before passing over the second restriction wall portion. In the annular space, since the shearing force does not act even during driving, the grease accumulated therein is solidified and immobilized. Therefore, leakage of grease can be prevented efficiently without selecting the direction of the transmission.

  Further, the rotating body has a small diameter portion that is continuous with the sun gear, a large diameter portion that is continuous with the small diameter portion through a stepped portion and has a larger diameter, and is the first in the axial direction. It is preferable that the step portion is located between the restriction wall portion and the second restriction wall portion.

  Then, since the centrifugal force is larger in the large diameter portion than in the small diameter portion, the grease leaking through the rotating body can be stably blown into the annular space.

  More specifically, the transmission unit includes a carrier that is provided coaxially with the rotating body and is rotatably supported. The carrier includes a first support surface that faces the second connecting portion and is orthogonal to a rotation axis, and a plurality of support pins that protrude perpendicularly from a peripheral portion of the first support surface. The housing includes a first housing portion that houses the first connecting portion side, and a second housing portion that houses the second connecting portion side and is assembled to the first housing portion.

  The first restriction wall portion is provided in the second housing portion. A second support surface parallel to the first support surface is provided on the first connecting wall side of the first restriction wall. The planetary gear is inserted into the support pin and supported by being sandwiched between the first support surface and the second support surface.

  If the transmission is configured in this way, the planetary gear can be sandwiched between the carrier and the casing using the first restriction wall, and the carrier is supported rotatably about the rotation axis. The gear can be supported so as to revolve around the rotation axis. Therefore, the carrier structure can be simplified and the assembly can be facilitated as compared with the conventional product in which the planetary gear is incorporated in the carrier.

  Furthermore, an assembly member formed separately from the housing may be included, and the second restriction wall portion may be configured by the assembly member.

  Since the annular space described above has a structure in which the inside of the hole is cut out, it is difficult to integrally form the casing. However, it can be easily formed by assembling the second restricting wall portion by assembling a separate assembly member to the housing.

  For example, a fitting hole that opens to the opposite side of the first housing part is formed in the second housing part. The assembly member is formed in an annular shape having substantially the same outer diameter as the bearing. The bearing and the assembly member are fitted into the fitting hole in this order from the opening side and attached to the second housing part. And the part by the side of the said rotary body in the said 2nd control wall part is made to leave | separate from the said bearing.

  If it does so, an annular space can be easily formed only by fitting and attaching an assembly member and a bearing to a fitting hole in order. It is also possible to prevent rotational resistance from occurring between the assembly member and the bearing.

  In particular, it is preferable to use grease having a consistency of 1 or more.

  Then, for example, even if the transmission is placed horizontally or upside down, the grease that accumulates in the annular space can be stably held in the annular space.

  As described above, according to the present invention, since the grease leakage can be effectively suppressed without using an oil seal, the transmission has excellent versatility and productivity. Can be provided.

It is a perspective view showing the outline of the transmission of this embodiment. In order to show the internal structure, a part of the housing is removed. It is a schematic sectional drawing of a transmission. It is a disassembled perspective view for demonstrating the one part assembly | attachment state of a transmission. It is a perspective view showing the outline of an assembly member. It is a schematic sectional drawing which shows the principal part of a transmission. It is a schematic sectional drawing which shows the transmission of another Example.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the following description is merely illustrative in nature and does not limit the present invention, its application, or its use.

  1 and 2 show a reduction gear (transmission) to which the present invention is applied. The speed reducer includes a first connecting portion 1 and a second connecting portion 2 that rotate about a rotation axis A, a speed reducing portion 3 (transmission portion) interposed therebetween, and a first connecting portion 1 and a second connecting portion. The unit 2 and the housing 4 that accommodates the speed reduction unit 3 are configured. Note that the speed reducer of the present embodiment is a two-stage type speed reducer, and a two-stage gear mechanism 3a, 3b is provided in the transmission unit.

  The housing 4 is a hollow cylindrical block-shaped metal workpiece, and includes a first housing portion 41 that houses the first connecting portion 1 side and a second housing portion 42 that houses the second connecting portion 2 side. It is configured. The 1st housing | casing part 41 and the 2nd housing | casing part 42 are mutually assembled | attached by abutting back and forth. For convenience, the first connecting portion 1 side in the direction of the rotation axis A will be described as the front and the second connecting portion 2 side as the rear as necessary.

  The first housing part 41 has a cylindrical first peripheral wall part 41a and an end wall part 41b that closes an opening on the front side of the first peripheral wall part 41a, and a shaft hole 41c is formed at the center of the end wall part 41b. Is open.

  The 1st connection part 1 has the output shaft 1a and the shaft base 1b provided continuously from the output shaft 1a to the axial direction. The output shaft 1a protrudes outward from the shaft hole 41c, and the shaft base portion 1b is rotatably supported by the first housing portion 41 via the first bearing 5. An oil seal 6 is provided between the first connecting portion 1 and the shaft hole 41c.

  The speed reduction unit 3 includes a first gear mechanism 3a at the front stage and a second gear mechanism 3b at the rear stage. Grease is injected into the deceleration unit 3 as lubricating oil (details of the grease will be described later).

  The first gear mechanism 3 a includes a hollow ring-shaped first carrier 31 provided integrally with the shaft base portion 1 b of the first connecting portion 1, and three pieces that are equally arranged in the circumferential direction at the periphery of the first carrier 31. The first planetary gears 32, 32, and 32 are disposed on the outer side in the radial direction of the first carrier 31, and ring-shaped first internal gears 33 that mesh with the first planetary gears 32. The basic structure of the first carrier 31 is the same as that of the conventional product.

  Each first planetary gear 32 is rotatably supported by the first carrier 31 via first support pins 31a supported at both ends by the first carrier 31, and revolves freely around the rotation axis A. Can do. Each first planetary gear 32 is housed inside the first carrier 31, and a part of each first planetary gear 32 is exposed outwardly from each of the three window portions 31 b that open on the peripheral surface of the first carrier 31. . The rear end portion (corner portion) of the first carrier 31 is rotatably supported by the housing 4 via the intermediate bearing 7. In addition, a smooth bearing surface 31 c orthogonal to the rotation axis A is formed at the rear end portion (center portion) of the first carrier 31.

  The first internal gear 33 is fitted into the first housing part 41 and is supported so as not to rotate. And the 1st sun gear 34 of the 2nd gear mechanism 3b is arrange | positioned so that it may mesh with each 1st planetary gear 32 inside the radial direction of the 1st carrier 31. As shown in FIG.

  As shown in FIG. 3, in addition to the first sun gear 34, the second gear mechanism 3 b includes a substantially disc-shaped second carrier 35 (carrier) provided integrally with the first sun gear 34, and a second sun gear 34. Three second planetary gears 36, 36, 36 that are equally arranged in the circumferential direction at the periphery of the carrier 35, and a ring shape that is arranged radially outward of the second carrier 35 and meshes with each second planetary gear 36. And a second internal gear 37.

  A smooth bearing surface 35 a orthogonal to the rotation axis A is provided on the front side portion of the second carrier 35. The bearing surface 35a is received by the bearing surface 31c of the first carrier 31 via a ring plate-shaped thrust bearing 8a. In addition, a smooth first support surface 35 b orthogonal to the rotation axis A is provided on the rear portion of the second carrier 35. From the periphery of the first support surface 35b, second support pins 35c that cantilever-support each second planetary gear 36 project perpendicularly to the first support surface 35b.

  The second internal gear 37 is fitted into the second housing portion 42 and is supported so as not to rotate. The intermediate bearing 7 is sandwiched between the second internal gear 37 and the first internal gear 33. And the 2nd sun gear 38 of the 2nd connection part 2 is arrange | positioned so that it may mesh with each 2nd planetary gear 36 inside the radial direction of the 2nd carrier 35. As shown in FIG.

  In addition to the second sun gear 38, the second connecting portion 2 has a multistage cylindrical input portion 21 (rotary body) that is integrally provided behind the second sun gear 38. Specifically, the input unit 21 includes a small-diameter portion 21a continuous to the second sun gear 38, a large-diameter portion 21b having a larger diameter, and a support portion 21c having a larger diameter. Yes. A stepped portion 21d having a stepped surface substantially orthogonal to the rotation axis A is formed between the small diameter portion 21a and the large diameter portion 21b. The step surface may be an inclined surface that is inclined from the small diameter portion 21a toward the large diameter portion 21b.

  A shaft attaching portion 22 for inserting and fixing a shaft of a rotary drive device such as a motor is provided at the rear end portion of the input portion 21. The output shaft 1a, the shaft base 1b, the first carrier 31, the first internal gear 33, the first sun gear 34, the second carrier 35, the second internal gear 37, the second sun gear 38, and the input unit 21 are either Is also arranged coaxially with the rotation axis A.

  As shown in FIG. 2, the second casing portion 42 is a cast product of a metal having a substantially cylindrical shape. In the thick cylindrical casing base portion 43 and the front end portion of the casing base portion 43, It has the substantially cylindrical 2nd surrounding wall part 44 extended in an axial direction from an outer peripheral edge, and the annular | circular shaped 1st control wall part 45 extended toward the radial inside from the inner peripheral edge. The second peripheral wall portion 44 is fixed integrally with the first peripheral wall portion 41a.

  As shown in FIG. 3, a smooth second support surface 46 parallel to the first support surface 35 b of the second carrier 35 is provided on the front side of the first restriction wall 45 in the housing base 43. That is, the first restriction wall portion 45 has a function of supporting the second carrier 35. Then, each second planetary gear 36 is inserted into each second support pin 35c, and each second planetary gear 36 is received by the second support surface 46 via the ring plate-shaped thrust bearing 8b. Then, the second carrier 35 and each second planetary gear 36 are sandwiched between the first carrier 31 and the second housing part 42 via the pair of thrust bearings 8a and 8b. By doing so, the second carrier 35 is supported to be rotatable about the rotation axis A, and each second planetary gear 36 is supported to be revolved about the rotation axis A.

  By comprising in this way, the structure of the 2nd carrier 35 can be simplified compared with the conventional carrier. Assembling can be done easily, improving productivity.

  The inside of the housing base 43 is formed in a multistage cylindrical shape that expands toward the rear. Specifically, the casing base 43 is formed with a cylindrical large-diameter hole 43a (insertion hole) that opens to the rear side. The inner diameter of the large-diameter hole 43a is set to be substantially the same as the outer diameter of the second bearing 9 (bearing). A cylindrical small-diameter hole 43b having a smaller diameter than the large-diameter hole 43a is formed coaxially with the large-diameter hole 43a. A bottom portion on the front side of the small-diameter hole portion 43b is configured by a first restriction wall portion 45. The small-diameter hole portion 43b communicates with the area of the speed reduction portion 3 in front of the small-diameter hole portion 43b through a circular opening 43c opened at the center thereof.

  The second bearing 9 and the assembly member 50 are fitted into the large diameter hole 43a in order from the opening side. These are attached to the housing base 43 by the retaining ring 10 so that they cannot be detached. A support portion 21 c of the input portion 21 is fitted into the second bearing 9. That is, the input part 21 is rotatably supported by the second housing part 42 via the second bearing 9 in a state where the second sun gear 38 is protruded from the circular opening 43c to the speed reduction part 3 side. The front end of the first restriction wall 45 is opposed to the small diameter portion 21a of the input portion 21 with a minute gap.

  FIG. 4 shows the assembly member 50. The assembly member 50 is a pressed product of a metal plate and is formed in an annular shape having substantially the same outer diameter as that of the second bearing 9. The assembly member 50 includes an outer peripheral side sandwiching part 50a supported by being sandwiched between the second housing part 42 and the second bearing 9, and an inner peripheral side part positioned substantially parallel to the sandwiching part 50a. It has the front-end | tip part 50b and the inclination part 50c between these connected to the clamping part 50a and the front-end | tip part 50b.

  The assembly member 50 is assembled to the housing base 43 with the distal end portion 50b and the inclined portion 50c (inner peripheral side portion) separated from the second bearing 9 so as not to interfere with the input bearing 21 side portion of the second bearing 9. (See FIG. 5). Moreover, the front-end | tip part 50b has opposed the large diameter part 21b of the input part 21 through the fine clearance gap. By doing so, the assembly member 50 is prevented from coming into contact with the second bearing 9 and the input portion 21 to generate rotational resistance. By assembling the assembling member 50 to the casing base portion 43, the second restriction wall portion 51 is configured.

  In other words, by providing the first restriction wall portion 45 and the second restriction wall portion 51 apart from the front and rear of the small diameter hole portion 43b, the front and rear sides of the small diameter hole portion 43b are arranged on the first restriction wall portion 45 and the second restriction wall portion 51b. By partitioning with the wall portion 51, the housing base portion 43 has an annular space 47 that communicates with the region of the speed reduction portion 3 through the circular opening 43 c, and faces the front end portion of the input portion 21. Is formed.

  Since the annular space 47 has a structure in which the inside of the hole is hollowed out, it is difficult to form the annular space 47 integrally with the housing base 43, but it is easy to assemble another assembly member 50 to the housing base 43. Can be formed.

  Incidentally, an oil seal is generally provided between the speed reduction unit 3 and the input unit 21 to prevent grease leakage. On the other hand, this reducer is devised to prevent grease leakage without installing an oil seal in consideration of the properties of grease.

  First, since the annular space 47 described above is formed in the housing base 43, the grease leaking from the speed reduction unit 3 can be stably accumulated in the annular space 47 regardless of the installation direction of the speed reducer. It can be effectively prevented from leaking outside.

  As shown in FIG. 5 (in the figure, the grease is indicated by G), when the speed reducer is driven and the fluidity of the grease is increased by the shearing action, the grease travels through the input portion 21 and is connected to the second connection through the circular opening 43c. It becomes easy to leak to the part 2 side. When the grease leaks out, the input portion 21 rotates at a high speed. Therefore, the grease is formed on the outer side in the radial direction by the centrifugal force before the tip portion 50b of the second restriction wall portion 51 is exceeded. It is thrown into the annular space 47.

  In the annular space 47, since the shearing force does not act even when the speed reducer is driven, the grease accumulated therein is solidified and immobilized. Due to the action of the centrifugal force, the grease can be stored in a well-balanced manner from the back of the annular space 47, which is advantageous in that it can be firmly attached to the housing base 43.

  By forming a step in the input portion 21, grease leakage can be prevented more stably. Specifically, the step portion 21 d is located between the first restriction wall portion 45 and the second restriction wall portion 51 in the axial direction. Since the centrifugal force is larger in the large-diameter portion 21b than in the small-diameter portion 21a, the grease leaking through the input portion 21 can be stably blown into the annular space 47.

  When viewed from the direction of the rotation axis A, the tip of the first regulating wall 45 is positioned inside the outer peripheral edge of the large-diameter portion 21b, and the diameter of the circular opening 43c is set to the diameter of the small-diameter portion 21a and the large-diameter portion 21b. It is preferable to form in the magnitude | size between these diameters. Then, the grease leaking out from the circular opening 43c is received by the step surface of the step portion 21d, so that the grease can be prevented from directly entering the gap between the second restriction wall portion 51 and the large diameter portion 21b. The grease can be blown into the annular space 47 more stably.

  As the grease, it is preferable to use a grease having a predetermined property. Specifically, a grease having a consistency of 1 or more is preferable, and a grease having a consistency of 2 or more is particularly preferable. Consistency is an index representing the properties of grease and can be measured based on JIS standards (JIS K 2220). The higher the value, the harder the grease.

  If the grease has a consistency of 1 or more, it depends on the type of grease, but even if the annular space 47 is turned sideways or in the opposite direction, it hardly moves and is fixed, and can be stably held under normal use conditions. On the other hand, when the grease has a consistency of less than 1, it may not be retained depending on the type of grease and the direction of the annular space 47. If the consistency is 2 or more, the grease can be stably held in the annular space 47 almost without choosing the type of grease.

  The transmission of the present invention is not limited to the above-described embodiment, and includes various other configurations.

  As shown in FIG. 6, the present invention can also be applied to a one-stage type transmission. In this case, the first carrier 31 or the like is not necessary. Therefore, the second carrier 35 is provided on the shaft base 1 b instead of the first carrier 31. Since other main configurations are the same as those of the above-described embodiment, members having the same functions are denoted by the same reference numerals and description thereof is omitted.

  The first connecting portion 1 and the second connecting portion 2 do not necessarily have the same rotation axis. By interposing a bevel gear or the like, the respective rotation axes may be orthogonal. The assembly member 50 may be a block-shaped member.

  The transmission of the present invention can be used for transmissions installed in various industrial equipment such as industrial robots and packaging machines.

DESCRIPTION OF SYMBOLS 1 1st connection part 2 2nd connection part 3 Deceleration part (transmission part)
4 Housing 9 Second bearing (bearing)
21 Input unit (rotating body)
21a Small diameter portion 21b Large diameter portion 21c Support portion 21d Step portion 31 First carrier 35 Second carrier 35b First support surface 35c Second support pin 36 Second planetary gear 37 Second internal gear 38 Second sun gear 41 First Case portion 42 Second case portion 43 Case base portion 43a Large diameter hole portion 43b Small diameter hole portion 43c Circular opening 45 First restriction wall portion 46 Second support surface 47 Annular space 50 Assembly member 51 Second restriction wall portion A Axis of rotation

Claims (6)

A first connecting portion and a second connecting portion that are rotatably supported;
A transmission unit interposed between the first connection unit and the second connection unit and having a plurality of planetary gears;
A housing that houses the first connecting portion, the second connecting portion, and the transmission portion;
Including
A transmission in which grease is injected into the transmission unit,
The second connecting part is
A rotating body rotatably supported by the housing via a bearing;
A sun gear provided coaxially with the rotating body and engaged with the planetary gear;
With
Between the sun gear and the bearing, a first restricting wall portion and a second restricting wall portion projecting from the housing toward the rotating body are provided apart from each other in the rotation axis direction. transmission. The transmission according to claim 1, wherein
The rotating body is
A small diameter portion continuous to the sun gear;
Continuing to the small diameter portion through the stepped portion, a large diameter portion having a larger diameter than this,
Have
A transmission in which the step portion is located between a first restriction wall portion and a second restriction wall portion in the axial direction. The transmission according to claim 1 or 2,
The transmission unit is
A carrier provided coaxially with the rotating body and rotatably supported;
With
The carrier is
A first support surface that is orthogonal to the rotation axis and faces the second connecting portion;
A plurality of support pins projecting vertically from the periphery of the first support surface;
Have
The housing is
A first housing portion accommodating the first connecting portion side;
A second housing part that accommodates the second connecting part side and is assembled to the first housing part;
With
The first restriction wall portion is provided in the second housing portion,
A second support surface parallel to the first support surface is provided on the first connecting portion side of the first restriction wall portion,
A transmission in which the planetary gear is inserted into the support pin and supported by being sandwiched between the first support surface and the second support surface. The transmission according to claim 3,
Including an assembly member formed separately from the housing;
A transmission in which the second restriction wall portion is constituted by the assembly member. The transmission according to claim 4, wherein
The second housing part is formed with a fitting hole that opens on the opposite side of the first housing part,
The assembly member is formed in an annular shape having substantially the same outer diameter as the bearing,
The bearing and the assembly member are fitted in the fitting hole in this order from the opening side and attached to the second housing part,
A transmission in which a portion on the rotating body side of the second regulating wall portion is separated from the bearing. The transmission according to any one of claims 1 to 5,
A transmission in which a grease having a consistency of 1 or more is used as the grease.

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