JP2005344798A - Planetary gear mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a planetary gear mechanism capable of improving characteristics such as strength and durability as a whole, by avoiding partial acting of a load caused by the torque transmission between a ring gear and an external member on a specific member. <P>SOLUTION: This planetary gear mechanism 12 engages a carrier 17 with a fixing part 18 so as not to rotate, transmits torque between a sun gear 13 and the ring gear 14 via pinion gears 15 and 16, and transmits the torque between the ring gear 14 and the external member 21 arranged on its outer peripheral side. An engaging degree of the fixing part 18 with the carrier 17 in a first area α including a torque transmission part A between the ring gear 14 and the external member 21, is set lower than an engaging degree in a second area β of not including the torque transmission part A. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a planetary gear mechanism that mainly includes a sun gear, a ring gear, and a carrier that rotatably holds a plurality of pinion gears disposed between the sun gear and the ring gear.

  In a planetary gear mechanism having three elements of a sun gear, a ring gear, and a carrier, by setting any one of these three elements as an input element and any other as an output element, and further setting another element as a fixed element. The planetary gear mechanism can function as a speed reducer, a speed increasing device, a reversing device, or the like. Further, by connecting any two elements so as to rotate integrally, the entire planetary gear mechanism can be integrated, that is, the input element and the output element can be rotated directly.

  As a device utilizing the function of such a planetary gear mechanism, a so-called single pinion having a sun gear, a ring gear arranged outside the sun gear, and a carrier holding a pinion gear meshed with the sun gear and the ring gear is provided. Patent Document 1 describes an example of a power transmission device that is a planetary gear mechanism of the type and includes a speed change mechanism that changes the rotational speed of an electric motor by fixing either the sun gear, the ring gear, or the carrier. .

In the speed change mechanism described in Patent Document 1, the carrier is fixed to the casing side by spline fitting, and external teeth formed so as to rotate integrally with the ring gear on the outer periphery of the ring gear are connected via a gear pair and a differential. Counter gears connected to the wheels are meshed. Therefore, torque is transmitted between the external teeth and the counter gear, that is, between the ring gear and the counter gear, and torque is transmitted between the ring gear and the sun gear via the pinion gear. The rotation speed is changed.
JP 2002-274201 A

  In the planetary gear mechanism described in Patent Document 1, the balance of forces acting on each element such as a ring gear, a pinion gear, or a carrier when torque is transmitted between the counter gear and the ring gear is shown in FIG. FIG. 3 shows a simplified diagram. 2 and 3, a plurality of pinion gears (herein, pinion gears 3 and 4) are arranged between the sun gear 1 and the ring gear 2, and the carrier 5 holding these pinion gears 3 and 4 is attached to the casing 6. It is fixed by splines 7 and 8. Further, the external teeth 9 formed on the outer peripheral surface of the ring gear 2 and the counter gear 10 are meshed with each other. And the ring gear 2 is supported by the casing 6 via the bearing 11 fitted by the outer periphery.

  In such a usage pattern, the load F1 accompanying torque transmission acts on the meshing portion of the ring gear 2 and the counter gear 10. 2 and 3, the pressure angle is neglected, and the load F1 acts in a direction perpendicular to the line connecting the center of the sun gear 1 and the center of the counter gear 10. Here, FIG. 2 shows a balance of forces acting on each element when the ring gear 2 and the bearing 11 supporting the ring gear 2 are assumed to be completely rigid (that is, in an ideal state). When the load F1 is applied in such an ideal state, the load F2 that is the support reaction force of the bearing 11 is a reaction force balanced with the load F1 in the normal direction of the outer periphery of the ring gear parallel to the direction in which the load F1 is applied. Works. In addition, loads F3 and F4 that are equal to each other (balanced with each other) act on the meshing portions of the ring gear 2 and the pinion gears 3 and 4 ((a) in FIG. 2).

  Further, in that case, the loads F5 and F6 received from the pinion pins 3a and 4a of the pinion gears 3 and 4 act on the carrier 5 to act on the spline fitting portions between the outer peripheral portion of the carrier 5 and the casing 6. The loads F7 and F8 that are balanced with each other act (FIG. 2B). Therefore, in such an ideal state, with the transmission of torque between the ring gear 2 and the counter gear 10, forces (F3, F4) that are balanced with each other are applied to the pinion gears 3, 4.

  However, in reality, the ring gear 2 and the bearing 11 are not completely rigid bodies, and are subject to deflection or deformation or rattling due to the clearance of the support portion by receiving external force. Therefore, the balance of the forces acting on each element in that case will be described with reference to FIG. 3. When the load F1 acts to cause the ring gear 2 or the bearing 11 to bend, deform, or rattle, that is, the load F1 is By acting to cause deflection or deformation or to move the ring gear 2 by the amount of play, the support reaction force of the bearing 11 is reduced, and a load F2 ′ smaller than the load F2 in the ideal state described above is obtained. Become.

  Therefore, the load F3 ′ acting on the pinion gear 3 located near the meshing portion between the ring gear 2 and the counter gear 10 becomes larger than the load F4 ′ acting on the pinion gear 4 located far from the meshing portion. The difference between the load F3 ′ and the load F4 ′ compensates for the lack of reaction force against the load F1 due to the decrease in the load F2 ′, and the forces acting on each element are balanced ((a) in FIG. 3). .

  In this case, the carrier 5 receives a load F5 ′ received from the pinion pin 3a of the pinion gear 3 at a position close to the meshing portion corresponding to the difference between the load F3 ′ and the load F4 ′, and the load F5 ′. The load F6 ′ received from the pinion pin 4a of the pinion gear 4 located at a position far from the meshing portion is also applied. Further, each spline fitting portion between the outer peripheral portion of the carrier 5 and the casing 6 has a load F7 ′ acting on the spline fitting portion located at a position close to the meshing portion, and the meshing smaller than the load F7 ′. The load F8 ′ acting on the spline fitting portion located far from the portion acts (FIG. 3B).

  Therefore, as described in Patent Document 1 above, torque is transmitted between an external member such as a counter gear and a ring gear, and the carrier is fixed to a fixing member such as a case, via a plurality of pinion gears. In a planetary gear mechanism in which torque is transmitted between a ring gear and a sun gear, a load associated with torque transmission is concentrated on a specific pinion gear arranged near the torque transmission portion among a plurality of pinion gears. Will act (biased). Therefore, a large load is applied to the specific pinion gear, and this causes the problem that the strength and durability of the planetary gear mechanism are reduced, or the entire planetary gear mechanism depends on the strength or durability of the specific pinion gear. There was a problem that the strength and durability were limited.

  The present invention has been made paying attention to the above technical problem, and avoids the fact that the load accompanying torque transmission with the external member acts on a specific member and acts as a whole on the strength or An object of the present invention is to provide a planetary gear mechanism capable of improving characteristics such as durability.

  In order to achieve the above object, the invention of claim 1 comprises, as elements, a sun gear, a ring gear, and a carrier that rotatably holds a plurality of pinion gears arranged between the sun gear and the ring gear, and the carrier. Are engaged with each other so as not to rotate with respect to a predetermined fixing part, and transmit torque between the sun gear and the ring gear via the pinion gear, and between the ring gear and an external member disposed on the outer peripheral side thereof. In the planetary gear mechanism that transmits torque between the engagement portions for preventing the carrier from rotating with respect to the fixed portion, a predetermined arc in a circumferential direction including a torque transmission portion between the ring gear and the external member Provided in a first region having a long length and a second region having a predetermined arc length in a circumferential direction not including the torque transmission portion, The engagement degree of the engagement portion in the detent direction in the region is set lower than the engagement degree of the engagement portion in the detent direction in the second region. .

  The invention of claim 2 is characterized in that, in the invention of claim 1, a plurality of the pinion gears are arranged in the second region.

  According to the first aspect of the present invention, when torque is transmitted between the ring gear of the planetary gear mechanism and the external member disposed on the outer peripheral side of the ring gear, the influence of the load accompanying the torque transmission is large. The degree of engagement between the carrier and the fixed part in the first region is set to be lower than the degree of engagement between the carrier and the fixed part in the second region where the influence of the load accompanying torque transmission is small. In other words, the movement allowable degree of the engaging part between the carrier and the fixed part in the first region is set higher than the movement allowable degree of the engaging part between the carrier and the fixed part in the second region. Therefore, the load accompanying torque transmission between the ring gear and the external member is distributed or equalized to each pinion gear, and it is avoided that the load acts on a specific pinion gear. And the intensity | strength and durability as the whole planetary gear mechanism can be improved.

  According to the invention of claim 2, the influence of the load accompanying the torque transmission is smaller and the degree of engagement between the carrier and the fixed part is set higher than in the first region where the influence of the load accompanying the torque transmission is large. A plurality of pinion gears are arranged in the second region. Therefore, in the second region where the load acting on the pinion gear is increased by setting the degree of engagement between the carrier and the fixed portion to be high, the load can be distributed to a plurality of pinion gears and biased toward a specific pinion gear. It can avoid that a load acts and can improve the intensity | strength and durability as the whole planetary gear mechanism.

  Next, the present invention will be described based on specific examples. First, an example of the planetary gear mechanism 12 targeted by the present invention will be briefly described with reference to FIG. 4. In FIG. 4, the planetary gear mechanism 12 is a so-called single pinion type planetary gear mechanism, and includes a sun gear 13 and the sun gear 13. And a carrier 17 holding a plurality of pinion gears (herein, pinion gears 15 and 16) meshed with the sun gear 13 and the ring gear 14 in a rotatable manner. Of the configuration. The ring gear 14 is rotatably supported by a predetermined fixing portion, for example, a casing 18 via a bearing 19.

  Further, external teeth 20 are formed on the outer peripheral surface of the ring gear 14. Further, a counter gear 21 corresponding to the external member of the present invention is arranged at a predetermined position on the outer peripheral side of the ring gear 14. And this counter gear 21 and the external tooth 20 in the ring gear 14 mesh. Therefore, the meshing portion of these teeth is the torque transmission position, and the position in the circumferential direction is a position that does not change substantially constant.

  The planetary gear mechanism 12 shown in FIG. 4 has a carrier 17 as a fixed element, and the carrier 17 is connected to the casing 18 through a predetermined engagement means 22 in a non-rotating state. The engaging means 22 is for engaging the carrier 17 with respect to the casing 18 so as to prevent the carrier 17 from rotating. The engaging means 22 engages the engaging portion in the rotation preventing direction (that is, the circumferential direction of the carrier 17). It has a structure that can be set by adjusting the degree of matching.

  As the engaging means 22 having such a structure, various means can be adopted as necessary. For example, splines with chipped teeth that allow the engagement portion to move in the detent direction, splines with large groove widths that allow the engagement portion to move in the detent direction, and elasticity such as springs or rubber A ring-shaped support member with a built-in member can be employed.

  In the planetary gear mechanism 12 described above, since the carrier 17 is a fixed element, either the sun gear 13 or the ring gear 14 is an input element and the other is an output element. Torque is transmitted between the ring gear 14 and the counter gear 21. FIG. 1 shows the balance of forces acting on each element such as the ring gear 14, the pinion gears 15 and 16, and the carrier 17, or the behavior of the ring gear 14 and the carrier 17 at that time. In addition, this FIG. 1 is simplified and described like FIG. 2 and FIG. 3 mentioned above. In the example shown here, a plurality of pinion gears, that is, two pinion gears 15 and 16 here are arranged at symmetrical positions with the sun gear 13 sandwiched therebetween, and a carrier 17 holding these pinion gears 15 and 16 is attached to the casing 18. Splines 23 are provided as engaging means for maintaining the engaged state so as not to rotate. Further, the external gear 20 formed on the outer peripheral surface of the ring gear 14 and the counter gear 21 are meshed with each other. And the ring gear 14 is supported by the casing 18 via the bearing 19 fitted by the outer periphery.

  As shown in FIG. 1, if the ring gear 14 is relatively rotated counterclockwise and its external teeth 20 are meshed with the counter gear 21, for example, between the meshed portions of these teeth, that is, between the ring gear 14 and the counter gear 20. In the torque transmission part A, a load f1 accompanying torque transmission therebetween is generated in the right direction in FIG. Here, in the planetary gear mechanism according to the present invention, when the load f1 as described above is applied, the load f1 can be prevented from acting only on a specific pinion gear. In other words, as described above, the spline 23 for engaging the carrier 17 so as to prevent the carrier 17 from rotating with respect to the casing 18 depends on the magnitude of the ratio of the influence of the load f1, and the anti-rotation direction of the engaging portion. The degree of engagement at is set so as to differ depending on the height.

  Specifically, the degree of engagement in the region α including the torque transmission part A is set lower than the degree of engagement in the region β not including the torque transmission part A. That is, the spline 23 in the region α including the torque transmission portion A and having a relatively large proportion of the influence of the load f1 acting on the torque transmission portion A prevents the rotation of the engaging portion between the carrier 17 and the casing 18. The engagement state (that is, the state where the degree of engagement is low) is sufficiently allowed, but the torque transmission part A is not included, and the influence of the load f1 acting on the torque transmission part A is affected. A fitting state in which the spline 23 in the region β where the receiving ratio is relatively small does not substantially allow the engagement portion between the carrier 17 and the casing 18 to move in the detent direction (that is, a state in which the degree of engagement is high). Has been.

  More specifically, the groove width is sufficiently large with respect to the tooth width so that the engaging portion of the spline 23 in the region α does not function as an engaging member (for example, the portion has a so-called missing tooth). In a state where the spline 23 is fitted in the region β, the tooth width and the groove width of the spline 23 are, for example, a general spline. Are set to predetermined dimensions so as to fit each other. Therefore, the region α corresponds to the first region in the present invention, the region β corresponds to the second region in the present invention, and the degree of engagement of the spline 23 in the region α in the detent direction is the region β. The teeth and grooves of each part of the spline 23 are formed so as to be lower than the degree of engagement of the spline 23 in the direction of rotation prevention.

  In FIG. 1, when the load f1 is applied in the torque transmission part A as described above, the spline 23 in the region α is allowed to move in the detent direction, that is, the degree of engagement in the detent direction is low. By setting the state, the carrier 17 can move in the left-right direction in FIG. 1, that is, in the direction indicated by the arrow V3 in FIG. 1B, and the degree of engagement in the detent direction in the region β is increased. With the fitting part B of the high spline 23 as the center of rotation, the carrier 17 rotates in the clockwise direction, that is, in the direction indicated by the arrow V4 in FIG. Since the carrier 17 can move in this way, the ring gear 14 can also move in the left-right direction in FIG. 1, that is, in the direction indicated by the arrow V1 in FIG. The ring gear 14 rotates in the counterclockwise direction, that is, in the direction indicated by the arrow V2 in FIG.

  In this way, when the load f1 is applied in the torque transmission portion A, the ring gear 14 is allowed to rotate in the direction of the arrow V2, thereby suppressing a decrease in the load f2, that is, the support reaction force of the bearing 19. As a result, it is avoided that a load acts on a specific pinion gear among the plurality of pinion gears 15 and 16 in a biased manner. That is, when the load f1 is applied in the torque transmitting portion A, the support reaction force of the bearing 19, that is, the load f2 is substantially balanced with the load f1 by receiving the support reaction force of the bearing 19 while being moved in the direction of the arrow V2. In this state, the respective loads f1 and f2 act on the ring gear 14. Therefore, the loads f3 and f4 acting on the pinion gears 15 and 16 with the transmission of torque at that time are also substantially balanced with each other ((a) in FIG. 1).

  At this time, the loads f5 and f6 that the carrier 17 receives from the pinion pins 15a and 16b of the pinion gears 15 and 16 are substantially balanced with each other. At that time, the load f7 acts on the fitting portion B of the spline 23, but the load f8 acts as a support reaction force of the torsion joint portion 27 (see FIG. 6 described later) of the carrier 17, and the carrier 17 The load acting on each part is almost balanced ((b) in FIG. 1).

  FIGS. 5 and 6 show examples of the carrier 17 and the casing 18 having the spline 23 having a large groove width that allows movement in the detent direction in the region α as described above. FIG. 5A is a diagram showing a configuration of the carrier 17 in which the teeth of the spline 23 are formed on the outer peripheral portion, and FIG. 5B is a diagram in which the teeth of the spline 23 of the carrier 17 are fitted. It is a figure which shows the structure of the casing 18 in which the groove | channel of the spline 23 formed was formed.

  In FIG. 5A, five pinion gears 24, 25, 26, 27, and 28 are rotatably held by the carrier 17, and the teeth of the spline 23 having the same shape are formed on the outer periphery of the carrier 17. 29a thru | or the tooth | gear 29j are formed. On the other hand, in FIG. 5B, the housing portion 30 of the carrier 17 is formed inside the casing 18 and concentrically with the ring gear 14 meshed with the counter gear 21. Grooves 31a to 31e of the spline 23 and grooves 32a to 32e of the spline 23 are formed with different groove widths in the peripheral portion. That is, the grooves 31a to 31e located in the region α have a sufficiently large width with respect to the tooth widths of the teeth 29a to 29j in order to reduce the degree of engagement of the spline 23 in the detent direction. (To the extent that the teeth 29a to 29j and the grooves 31a to 31e do not function as engaging members). Then, the grooves 32a to 32e located in the region β have a groove width of the teeth so that the degree of engagement of the spline 23 in the detent direction is higher than the degree of engagement by the grooves 31a to 31e. It is formed so that a general spline fits to the tooth width of 29a thru | or the tooth | gear 29j.

  Then, the teeth 29a to 29e of the spline 23 are fitted into the grooves 31a to 31e of the spline 23, respectively, and the teeth 29f to the teeth 29j of the spline 23 are fitted to the grooves 32a to 32e of the spline 23, respectively. Thus, the carrier 17 is engaged with the casing 18 so as not to rotate. Therefore, a plurality of pinion gears 24, 25, and 26 among the five pinion gears are arranged in the region β that does not include the torque transmission portion A between the ring gear 14 and the counter gear 21. As described above, by arranging the plurality of pinion gears 24, 25, and 26 in the region β where the influence of the load f1 accompanying torque transmission is small and the degree of engagement between the carrier 17 and the casing 18 is set high, The influence of the load f1 can be effectively distributed to the plurality of pinion gears 24, 25, and 26.

  FIG. 6 is a cross-sectional view showing the configuration of the planetary gear mechanism 12 having the carrier 17 as described above and a part of the casing 18. In FIG. 6, the carrier 17 is spline-fitted with the casing 18 at the fitting portion B of the spline 23 in the region β, and is also fitted with the casing 18 at the brazing joint portion 33.

  As described above, in the above planetary gear mechanism 12 according to the present invention, the fitting of each part of the spline 23 is performed in consideration of the influence of the load f1 that acts along with the torque transmission between the ring gear 14 and the counter gear 21. By varying the combined state, the degree of engagement in the region α including the torque transmission part A is set lower than the degree of engagement in the region β not including the torque transmission part A. Therefore, it is possible to avoid the load acting on each of the plurality of pinion gears 15, 16 accompanying the transmission of the torque from acting only on a specific pinion gear, and to equalize the load applied to each pinion gear 15, 16. can do. As a result, characteristics such as the strength and durability of a specific pinion gear do not restrict the overall strength and durability of the planetary gear mechanism and improve the overall strength and durability of the planetary gear mechanism. Can do.

  The present invention is not limited to the above specific example. In the above specific example, the first region (region α) including the torque transmission portion of the ring gear and the counter gear and the first region not including the torque transmission portion are included. An example in which the degree of engagement in the detent direction of the engaging portion between the carrier and the predetermined fixing member (casing) is set to be different in the two regions of the two regions (region β). Although three or more regions are set according to the torque transmission state, the degree of engagement is set appropriately for each region, and a plurality of regions are transmitted along with the torque transmission. The load acting on the pinion gear can be evenly distributed.

  In the above specific example, the means for engaging the carrier so as not to rotate with respect to the predetermined fixing member (casing) causes the engagement portion to move in the detent direction in the first region. Although an example in which the spline has a large allowable groove width is shown, for example, in the first region, the spline has a chipped tooth that allows the engagement portion to move in the detent direction. You can also Alternatively, in the second region, the carrier may be engaged with a predetermined fixing member so as not to rotate using a fastening mechanical element such as a bolt or a pin.

  Further, in the second region, the carrier is engaged so as not to rotate with respect to a predetermined fixing member by a normal spline fitting or using a fastening mechanical element such as the bolt or pin described above, In the first region, for example, a ring-shaped support member incorporating an elastic member such as a spring or rubber is used to allow the engagement portion to move in the detent direction. Also good. In this case, the load applied to the plurality of pinion gears can be equalized, and at the same time, the carrier vibration can be absorbed by the elastic member, so that the vibration and noise as a whole of the planetary gear mechanism can be prevented or suppressed.

  In the above specific example, the present invention is applied to a single-pinion type planetary gear mechanism. For example, in the case where the present invention is applied to a double-pinion type or other type of planetary gear mechanism. Also, the same actions and effects as described above can be obtained.

It is a schematic diagram for demonstrating the action state of the load in the planetary gear mechanism which concerns on this invention. It is another schematic diagram for demonstrating the action state of the load in a theoretical planetary gear mechanism. It is another schematic diagram for demonstrating the action state of the load in the conventional planetary gear mechanism. It is a skeleton figure which shows an example of the planetary gear mechanism which concerns on this invention. It is a schematic diagram for demonstrating the engagement state of the carrier and casing of the planetary gear mechanism which concerns on this invention. It is another schematic diagram (sectional drawing) for demonstrating the engagement state of the carrier and casing of the planetary gear mechanism which concerns on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 12 ... Planetary gear mechanism, 13 ... Sun gear, 14 ... Ring gear, 15, 16 ... Pinion gear, 17 ... Carrier, 18 ... Casing, 19 ... Bearing, 20 ... External tooth, 21 ... Counter gear, 23 ... Spline

Claims (2)

A sun gear, a ring gear, and a carrier that rotatably holds a plurality of pinion gears disposed between the sun gear and the ring gear as elements, and the carrier is engaged so as not to rotate with respect to a predetermined fixing portion; In the planetary gear mechanism that transmits torque between the sun gear and the ring gear via the pinion gear, and transmits torque between the ring gear and an external member disposed on the outer peripheral side thereof,
An engagement portion that prevents the carrier from rotating with respect to the fixed portion includes a first region having a predetermined arc length in a circumferential direction including a torque transmission portion between the ring gear and the external member, and the torque transmission portion. Provided in the second region of the predetermined arc length in the circumferential direction not including,
The degree of engagement in the detent direction of the engagement portion in the first region is set to be lower than the degree of engagement in the detent direction of the engagement portion in the second region. Planetary gear mechanism.   The planetary gear mechanism according to claim 1, wherein a plurality of the pinion gears are arranged in the second region.

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