JP4423782B2 - Planetary gear set - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a planetary gear set used in a transmission device such as an automatic transmission, and more particularly to a carrier structure thereof.
[0002]
[Prior art]
In a transmission device such as an automatic transmission, a planetary gear set that constitutes the transmission mechanism generally has an input shaft of the transmission mechanism, an output shaft, an intermediate shaft connected to them, or an axis around which the shafts are coaxially stacked. Be placed. In addition, friction members such as clutches and brakes that engage and disengage the sun gear, carrier, and ring gear as shifting elements with respect to the input / output member and the case are not subject to restrictions on the arrangement position, and therefore are related to the layout of the device. It is arranged between the planetary gear sets or on the outer periphery, and in particular, the brake friction member is often arranged on the outer periphery of the planetary gear set because its outer peripheral side is supported by the case of the transmission.
[0003]
[Problems to be solved by the invention]
By the way, the sun gear as a component of the planetary gear set disposed on the outer periphery of the shaft whose shaft diameter is determined in accordance with the transmission torque capacity is restricted from the inner diameter of the shaft by the outer diameter of the shaft. As the torque increases, the diameter increases, and the outer diameter of the entire planetary gear set increases accordingly. Therefore, when the friction member of the friction engagement element is arranged on the outer periphery, the outer diameter of the mechanism in which the friction members are combined becomes larger, and it is suitable for a device whose outer diameter is restricted like an automatic transmission mounted on a vehicle. As a result, this arrangement becomes extremely difficult.
[0004]
For planetary gear sets that transmit high torque, it is advantageous to increase the number of pinions in order to reduce the torque load per pinion from the viewpoint of ensuring its durability. With the increase, it becomes difficult to ensure the rigidity of the carrier that supports it, and torsional moment due to the reaction force of the mesh acts on the carrier that supports the pinion, making it difficult to maintain the rigidity of the carrier. It becomes. Such difficulty in maintaining rigidity is particularly remarkable in a Ravigneaux planetary gear set in which the pinion diameter is larger than the sun gear diameter. If the rigidity of the carrier is reduced due to such circumstances, the gears are not properly engaged due to the deformation, and problems such as a decrease in durability and generation of gear noise occur.
[0005]
Therefore, an object of the present invention is to provide a planetary gear set that allows a large number of pinions having a large outer diameter relative to the sun gear diameter to be secured while ensuring the rigidity of the carrier. The present invention also provides a carrier structure that prevents an increase in the radial dimension of the apparatus while securing a transmission torque capacity of the planetary gear set and the friction member when a friction member such as a clutch and a brake is disposed on the outer peripheral side of the planetary gear set. The purpose is to provide.
[0006]
[Means for Solving the Problems]
To achieve the above object, the present invention provides a planetary gear including a plurality of pinions meshing with a sun gear and a carrier that pivotally supports the pinions, the carrier having an annular peripheral wall that surrounds the outer periphery of the plurality of pinions over the entire circumference. In the set, the annular peripheral wall has a thin wall portion formed by recessing on the inner diameter side at a circumferential position corresponding to the disposition position of each pinion in accordance with the disposition number of the pinions. .
[0007]
Further, in the above configuration, the annular peripheral wall has a spline for preventing the friction member from rotating around the outer periphery, and the spline is missing in the thin wall portion, and the outer diameter of the thin wall portion is the tooth crest of the spline. It is effective to adopt a configuration that matches the outer diameter of the.
[0008]
In any of the above configurations, it is effective that each of the plurality of pinions is connected to at least another pinion that meshes with the ring gear.
[0009]
In each of the above-described configurations, the plurality of pinions and the other pinions can be applied as long pinions of a Ravigneaux planetary gear set.
[0010]
In the above configuration, the long pinion can be applied as a stepped pinion in which the plurality of pinions have a smaller diameter than the other pinions.
[0011]
[Action and effect of the invention]
According to the first aspect of the present invention, it is possible to obtain a planetary gear set in which a large number of pinions having a larger pinion diameter than the sun gear diameter are provided while securing an annular peripheral wall necessary for maintaining the rigidity of the carrier. In addition, since a large number of pinions can be arranged without impairing the rigidity of the carrier, the torque load per pinion can be reduced, thereby improving the durability of the planetary gear set.
[0012]
Next, in the configuration of the second aspect, when the friction engagement elements such as the clutch and the brake are arranged on the outer peripheral side of the planetary gear set, the spline teeth and the pinion for supporting the friction member of the friction engagement element are removed. Since the diameter can be circumscribed or partially overlapped, an increase in the diameter of the mechanism due to the overlapping arrangement of the planetary gear set and the friction engagement element in the radial direction can be suppressed. Therefore, when the torque capacity of the friction engagement element is required under a restricted outer diameter, the friction member is expanded in the inner diameter direction, and when the torque capacity of the planetary gear set is required, the carrier Can be selected to increase the diameter of the planetary gear set including the planetary gear set, and the degree of freedom in setting the transmission device using the planetary gear set is improved.
[0013]
According to the third aspect of the present invention, the transmission device can be made compact by arranging the friction engagement elements such as the clutch and the brake and the ring gear in the axial direction on the outer peripheral side of the planetary gear set.
[0014]
Further, in the configuration according to the fourth aspect, the effects corresponding to the configuration according to the first, second, or third aspect can be effectively exhibited particularly for the Ravigneaux type planetary gear set having a large number of pinions.
[0015]
Further, according to the fifth aspect of the present invention, it is easier to secure the space for disposing the friction members of the friction engagement elements such as the clutch and the brake disposed on the outer peripheral side of the planetary gear set.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. 1 to 4 show a first embodiment in which the present invention is applied to a Ravigneaux type planetary gear set having four pinion gear pairs.
[0017]
FIG. 1 shows a front view of pinion arrangement on a carrier, and FIG. 2 shows an overall axial cross section excluding a sun gear and a ring gear. This planetary gear set includes a small-diameter sun gear and a large-diameter A long gear connected to and integrated with a short pinion P1 that meshes with the sun gear to form a pinion gear pair and meshes with a small-diameter sun gear and with a large-diameter sun gear and meshes with another pinion that meshes with the short pinion P1 and a ring gear (not shown). A pinion P2 and a carrier C that pivotally supports the pinions via the pinion shafts S1 and S2 are provided. The carrier C has an annular peripheral wall 12 that surrounds the outer periphery of the long pinion P2 over the entire circumference. Furthermore, in accordance with the features of the present invention, the annular peripheral wall 12 of the carrier C is formed with a thin wall portion 12a formed by recessing in the outer diameter direction on the inner diameter side at a circumferential position corresponding to the arrangement position of each long pinion P2. Have In addition, the annular peripheral wall 12 has a spline 12b that prevents a friction member (not shown) on its outer periphery, and the spline 12b is missing in the thin wall portion 12a. The outer diameter of the thin wall portion 12a is the spline 12b. The outer diameter coincides with the outer diameter of the tooth crest 12c.
[0018]
More specifically, in the case of this embodiment, the planetary carrier C is composed of a main body A and a cover B as seen in FIG. The main body A has an opening through which a shaft coupled with a sun gear is connected at the center. The box structure portion 1 pivotally supports one end of each of the pinions P1 and P2, and extends outwardly along the opening of the box structure portion 1. The boss part 2 constituting the support part of the carrier C to the bridge, and the bridge constituting the connecting part to the cover B extending from the outer peripheral side of the box structure part 1 in the axial direction opposite to the extending direction of the boss part 2 Part 3 is provided. The box structure 1 is continuous in the outer end wall 10 that pivotally supports one end of the long pinion P2, the inner end wall 11 that pivotally supports one end of the short pinion P1, and the circumferential direction connecting them in the axial direction. It is a box structure in which an annular peripheral wall 12 and an inner wall 13 that connects the edges of both end walls 10 and 11 in the axial direction are integrally formed.
[0019]
More specifically, with reference to FIG. 3 in which the pinion gear pair in FIG. 1 is removed and FIG. 4 in which the rear surface of the main body is shown, the box structure portion 1 is in contact with the end face of each long pinion P2 . The end wall 10 is divided into four parts by being provided at a position corresponding to 2 ), and the end wall 10 has a substantially cross shape as a whole when viewed in the axial direction, and axial positions different from those end walls 10 (FIG. 3). At the position corresponding to the thrust washer W1 (see FIG. 2 ) that is substantially in contact with the end face of each short pinion P1 between the end walls 10 when viewed in the axial direction . An end wall 11 having a generally fan shape when viewed in the axial direction, an annular peripheral wall 12 connected to the outer peripheral side of both end walls 10, 11, and circulated around the outer periphery of the carrier C seamlessly, both sides of each end wall 10, end Wall 1 It is generally composed of a V-shaped internal wall 13 in the axial direction as viewed connecting the sides and the inner circumferential side. A large-diameter hole 10a that supports the pinion shaft S2 of each long pinion P2 is formed at the center of each end wall 10, and each end wall 11 also has a small diameter that supports the pinion shaft S1 of each short pinion P1. The hole 11a is formed.
[0020]
In this embodiment, the annular peripheral wall 12 of the box structure 1 is used on the outer peripheral surface of the annular peripheral wall 12 so as to be used as a hub of a clutch that connects to a brake or other transmission member that fixes the carrier C to a transmission case or the like. Splines 12b that support the friction material of the multi-plate brake or multi-plate clutch are formed. This spline 12b leaves a missing tooth at four locations in the circumferential direction corresponding to the thinned portion 12a thinned in accordance with the number of the long pinions P2, that is, a portion where a tooth shape is not formed by not performing gear cutting. When the annular peripheral wall 12 is viewed from the radially outer side to the inner side, a radial thickness approximately equal to the tooth height is secured with respect to the other portions. In addition, an appropriate number of oil discharge holes 30 penetrating the bridge portion 3 in the radial direction are formed in the bridge portion 3 in order to improve the discharge of the lubricating oil from the carrier C.
[0021]
The cover B serves as both a support portion for supporting the other end of each pinion P1, P2 via the pinion shafts S1, S2 and a support portion for the shaft of the carrier C itself, and has a central opening through which the shaft passes. A plate-like end wall portion 40 and a boss portion 41 whose inner diameter is the diameter of the central opening are integrally formed. In the middle portion of the inner and outer diameters of the end wall portion 40, there are four small-diameter holes 42 for supporting the pinion shaft S1 of each short pinion P1, and four large portions for supporting the pinion shaft S2 of each long pinion P2. A hole 43 having a diameter is formed, and the four peripheral surfaces of the end wall 3 positioned outside the large-diameter hole 43 in the radial direction are expanded in diameter relative to the other peripheral surfaces. One side of the step between the diameter-expanded portion 44 and another peripheral surface functions as a mutual circumferential positioning when the main body A and the cover B are assembled.
[0022]
The body A and the cover B having such a structure are fixed by axial bolting or the like by fitting a stepped portion at the tip of the bridge portion 3 of the body A to the outer periphery of the cover B and fixing it in an axial direction. The planetary carrier C is firmly integrated by welding or the like to connect the walls described above. In FIG. 2, a member denoted by reference numeral 5 screwed and fixed to the outer end surface of the cover B is an input member to the planetary carrier C. In this embodiment, the input member 5 is a hub for supporting the friction member by spline engagement. And also serves as an oil passage cover that guides lubricating oil from the shaft passing through the planetary carrier C to the in-shaft oil passages of the pinion shafts S1 and S2.
[0023]
In the planetary carrier C provided with the box structure portion, when a torsional stress is applied, the bridge portion 3 undergoes a tilt displacement in the torsional direction with respect to the carrier central axis with almost no deformation of itself, and the force is applied to both ends. Is transmitted to the box structure portion 1 and the end wall portion 40 as end walls of the plate, and the plate-like cover B and the main body A are deformed in a wavy shape in the carrier shaft circumferential direction. Therefore, if the rigidity of at least one of the end walls is increased, the wavy deformation of the both end walls can be reduced. In this embodiment, the rigidity of the box structure portion 1 as one end wall is improved by reinforcing the continuity of the annular peripheral wall 12 by reducing the thickness so as to avoid interference with the long pinion P2 to form a box structure. The wavy deformation is reduced, thereby reducing the collapse of the bridge portion 3, and as a result, the wavy deformation of the cover B, which is difficult to maintain the strength, is reduced. Incidentally, it has been verified that when the plate thickness of the cover B is variously changed and the deformation is seen, the influence of the change in the plate thickness on the deformation is small.
[0024]
The planetary gear set of the above embodiment configured as described above can be used for various forms of power transmission. For example, the carrier C and two sun gears are appropriately used as a power input element and a fixing element, and a ring gear is used as an output element. When the input member 5 is connected to a clutch, the annular peripheral wall 12 of the carrier C functions as a hub of a brake friction member supported by spline engagement therewith. In this case, the friction engagement element including the friction member is disposed in a space between the carrier C and the case in which the planetary gear set is accommodated. However, by applying the configuration of the present invention, the friction engagement element Since the frictional engagement element support structure that does not require a space in the radial direction between the inner diameter and the outer diameter of the carrier C is realized, the corresponding radial space is directed to the inner diameter direction of the frictional engagement element. This can be used to secure the brake torque capacity by expanding the diameter of the carrier C and to secure the gear transmission torque capacity by expanding the carrier C in the outer diameter direction.
[0025]
In particular, when this planetary gear set configuration is applied to a Ravigneaux planetary gear set for an automatic transmission mounted on a vehicle, the Ravigneaux planetary gear set generally has a long pinion that meshes with the sun gear diameter in relation to the gear ratio setting. However, according to the configuration of the embodiment according to the application of the present invention, the long pinion P2 and the long pinion P2 are difficult to pass through the outer circumference of the long pinion. Since the surrounding wall that avoids interference is established, the rigidity of the planetary carrier C in which the long pinion P2 has a large diameter and a large number can be maintained in order to secure a high torque transmission capacity.
[0026]
Next, FIG. 5 shows a second embodiment in which the thinned annular peripheral wall is applied to a similar Ravigneaux type planetary gear set having three pairs of pinion gears as in the first embodiment. In the case of this form, the missing tooth structure in the first embodiment is not applied. Since the remaining configuration is substantially the same as that of the first embodiment, the same reference numerals are assigned to the corresponding members and the description is omitted. Note that FIG. 5 is a cross section through which the pinion shafts S1 and S2 pass both in the vertical axis direction cross section, and thus the bridge portion of the carrier C does not appear, but in this case, the circumferential space between the pinion gear pair is the previous implementation. Since it is wider than the form, the bridge portion is provided so as to pass between the long pinion P2 and the short pinion P1 of the adjacent pinion gear pair. Even in the case of adopting such a configuration, the box structure of the carrier C is established, and durability by securing the torsional rigidity is obtained.
[0027]
As described above, since the application of the present invention is particularly effective, the Ravigneaux type planetary gear set has been exemplified as being applied to a meshing part of a short pinion of a long pinion and a large diameter sun gear having the same diameter. The invention can be applied to a configuration in which the meshing portion is a stepped pinion having a different diameter, and can be widely applied to other types of planetary gear sets.
[Brief description of the drawings]
FIG. 1 is a front view showing a carrier body of a planetary gear set according to a first embodiment of the present invention in a gear built-in state.
FIG. 2 is an overall cross-sectional view in the axial direction with the sun gear and ring gear of the planetary gear set removed.
FIG. 3 is a front view showing only the planetary carrier body.
FIG. 4 is a rear view of the planetary carrier body.
FIG. 5 is an overall sectional view in the axial direction with a sun gear and a ring gear removed from a planetary gear set according to a second embodiment of the present invention.
[Explanation of symbols]
C carrier P1 short pinion P2 long pinion 12 annular peripheral wall 12a thin wall portion 12b spline 12c tooth

Claims (5)

In a planetary gear set comprising a plurality of pinions meshing with a sun gear and a carrier that pivotally supports the pinions, the carrier having an annular peripheral wall that surrounds the entire circumference of the plurality of pinions,
The planetary gear set is characterized in that the annular peripheral wall has a thin wall portion formed by recessing on the inner diameter side at a circumferential position corresponding to the disposition position of each pinion in accordance with the disposition number of the pinions.   The annular peripheral wall has a spline that prevents the friction member from rotating on its outer periphery, and the spline is missing in the thin wall portion, and the outer diameter of the thin wall portion coincides with the outer diameter of the tooth crest of the spline. The planetary gear set according to claim 1.   The planetary gear set according to claim 1 or 2, wherein each of the plurality of pinions is connected to at least another pinion that meshes with a ring gear.   4. The planetary gear set according to claim 3, wherein the plurality of pinions and the other pinion are long pinions of a Ravigneaux planetary gear set.   The planetary gear set according to claim 4, wherein the long pinion is a stepped pinion in which the plurality of pinions have a smaller diameter than the other pinions.

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