Planetary transmission having planet carrier with thrust plate configured to aid in retaining pins to carrier body

A planetary transmission with a carrier body, a plurality of pins, a retaining ring and a thrust plate. The carrier body defines a plurality of pin apertures, which are disposed concentrically about a central axis, and a ring groove into which the retaining ring is received. Each of the pins has a stepped axial end that defines first and second axial end surfaces that are spaced apart from one another. The pins are received into the pin apertures such that the first axial end surface extends from the carrier body. The thrust plate has a plate body and a plurality of tabs that extend radially outwardly from the plate body. Each of the tabs overlies the second axial end surface of an associated one of the pins such that the thrust plate is disposed along the central axis between the second axial end surfaces and the retaining ring.

FIELD

The present disclosure relates to a planetary transmission having a planet carrier with a thrust plate that is configured to aid in retaining pins to a carrier body.

BACKGROUND

Planetary transmissions typically include a planet carrier that journally supports a plurality of planet gears that can be meshed with a sun gear and/or a ring gear. The planet carrier includes a carrier body and a plurality of pins on which the planet gears are received. The pins can be supported on one or both of their axial ends by the carrier body depending on the magnitude of the rotary load that is transmitted between the planet gears and the pins. Rotation of the pins about their longitudinal axes relative to the carrier body is typically not desirable, but can occur with some planet carrier configurations, especially when the planetary transmission transmits relatively large rotary loads. Various strategies have been conceived to resist relative rotation between the pins and the carrier body, including the use of an interference fit between the pins and the carrier body. While such configurations can be effective, they can frequently be difficult to service in the event that components housed in the carrier body need replacement.

SUMMARY

In one form, the present disclosure provides a planetary transmission with a carrier body, a plurality of pins, a retaining ring and a thrust plate. The carrier body has first and second plate members that each define a plurality of pin apertures that are disposed concentrically about a central axis. The second plate member defining a retaining ring groove. Each of the pins has a longitudinal pin axis and a stepped axial end that defines first and second axial end surfaces that are spaced apart from one another along the longitudinal pin axis. Each of the pins is received into a respective one of the pin apertures in the first plate member and a respective one of the pin apertures in the second plate member such that the first axial end surface extends from the second plate member on a side of the second plate member opposite the first plate member. The retaining ring is received in the retaining ring groove. The thrust plate has a plate body and a plurality of tabs that extend radially outwardly from the plate body. Each of the tabs overlies the second axial end surface of an associated one of the pins such that the thrust plate is disposed along the central axis between the second axial end surfaces and the retaining ring.

In another form, the present disclosure provides a method for assembling a planetary transmission. The method includes: providing a carrier body that defines a central axis; assembling pins and planet gears to the carrier body, each of the planet gears being disposed about an associated one of the pins, each of the pins having a longitudinal pin axis and a stepped axial end that defines first and second axial end surfaces that are spaced apart from one another along the longitudinal pin axis; inserting a sun gear through an assembly aperture in the carrier body; abutting a thrust plate to the carrier body, the thrust plate having a plate body and a plurality of tabs that extend radially outwardly from the plate body, each of the tabs overlying the second axial end surface of an associated one of the pins; and mounting a retaining ring into a ring groove formed in the carrier body to retain the thrust plate to the carrier body.

DETAILED DESCRIPTION

With reference toFIGS. 1 through 3of the drawings, a planetary transmission constructed in accordance with the teachings of the present disclosure is generally indicated by reference numeral10. The planetary transmission10can include a planet carrier cartridge12and a ring gear14. The planet carrier cartridge12can have a planet carrier assembly20, a sun gear22, and a plurality of planet gears24. In the example provided, the ring gear14, the sun gear22and the planet gears24are formed with helical gear teeth, but it will be appreciated that they could be formed with spur (straight) gear teeth in the alternative.

With reference toFIGS. 3 through 5, the planet carrier assembly20can include a planet carrier30, a thrust washer32, a thrust plate34and a retaining ring36. The planet carrier30can include a carrier body40and a plurality of pins42. The carrier body40can include a first plate member50and a second plate member52that is spaced apart from the first plate member50along a central axis54to receive the planet gears24therebetween. In the example shown, the first and second plate members50and52are discrete components that are assembled to one another. More specifically, the first and second plate members50and52are formed of compacted powdered metal and are joined by brazing when the first and second plate members50and52are sintered. Thereafter, the first and second plate members50and52can be machined as a unit. It will be appreciated, however, that the first and second plate members50and52could be unitarily and integrally formed.

The first plate member50can define a plurality of first pin apertures60and an internally toothed aperture62that defines a plurality of teeth that are disposed concentrically about the central axis54. The first pin apertures60can be spaced concentrically about the central axis54and can have a stepped configuration with a first portion64and a second, smaller diameter portion66. A shoulder68can be formed where the first and second portions64and66intersect one another.

The second plate member52can define a plurality of second pin apertures70, a plurality of tab recesses72, an assembly aperture74and a retaining ring groove76. A plurality of spacing legs78can be coupled to (e.g., unitarily and integrally formed with) one of the first plate member50and/or the second plate member52and can contact the other one of the first plate member50and the second plate member52to space the first and second plate members50and52apart from one another along the central axis54. In the example provided, the spacing legs78are unitarily and integrally formed with the second plate member52. The second pin apertures70can be spaced concentrically about the central axis54. The tab recesses72are formed into an axial end of the second plate member52on a side that faces away from the first plate member50. Each of the tab recesses72intersects an associated one of the second pin apertures70. The assembly aperture74is formed through the second plate member52and is sized to permit the sun gear22to be inserted into the space between the first and second plate members50and52. The retaining ring groove76is formed into the second plate member52concentrically about the central axis54. In the example provided, the retaining ring groove76is formed in a discontinuous manner by three circumferentially extending rib members80and is disposed radially inwardly of the second pin apertures70.

Each of the pins42can extend along a longitudinal pin axis84and can have a pin body86with a first axial end88and a second axial end90. The second axial end90can be stepped so as to have a first axial end surface92and a second axial end surface94that are spaced apart from one another along the longitudinal pin axis84. Each of the pins42can be received into one of the first pin apertures60in the first plate member50and one of the second pin apertures70in the second plate member52. In the example provided, the pin bodies86are received in a slip-fit manner into the first and second pin apertures60and70and the first axial ends88of the pins42are abutted against the shoulders68formed by the first pin apertures60. Configuration in this manner inhibits movement of the pins42along the longitudinal pin axes84relative to the first plate member50in a direction away from the second plate member52. It will be appreciated, however, that a press-fit or interference fit between the pins42and the first pin apertures60and/or the second pin apertures70could be employed to secure the pins42to the first plate member50and/or the second plate member52. The first axial end surfaces92of the pins42can extend along the central axis54past the axial end of the second plate member52that faces away from the first plate member50. The second axial end surfaces94of the pins42can be disposed along the central axis54at a desired location, such as flush or below the portions of the axial end of the second plate member52that define the bottom surfaces of the tab recesses72.

The thrust plate34has a plate body100and a plurality of tabs102that extend radially outwardly from the plate body100. In the example provided, the plate body100has an annular shape and is smaller in diameter than the assembly aperture74in the second plate member52. The tabs102are received into the tab recesses72in the second plate member52and overlie the second axial end surfaces94of the pins42. The tabs102and the tab recesses72can be shaped in a corresponding manner to limit or inhibit relative rotation between the thrust plate34and the carrier body40. In the example provided, the tabs102and tab recesses72have a triangular shape. Radially outer edges104of the tabs102cooperate with the portions of the pins42that extend between the first and second axial end surfaces92and94to inhibit or limit rotation of the pins42about the longitudinal pin axes84relative to the carrier body40. The tabs102can be formed so as to be offset along the central axis54relative to the plate body100. Configuration in this manner permits the plate body100to be received into the assembly aperture74while the tabs102are received in the tab recesses72and overlie the second axial end surfaces94on the pins42.

The retaining ring36is placed into the assembly aperture74and received in the retaining ring groove76in the second plate member52and secures the thrust plate34to the carrier body40. The retaining ring36abuts the plate body100on a side of the thrust plate that faces away from the pins42. Accordingly, the securing of the thrust plate34to the carrier body40via the retaining ring36also limits or inhibits movement of the pins42relative to the carrier body40along the central axis54in a direction away from the first plate member50. It will be appreciated that the retaining ring36is disposed radially inwardly of the pins42.

The sun gear22is rotatable about the central axis54and shown in the example provided as being unitarily and integrally formed with a shaft member110. The sun gear22includes first and second thrust surfaces112and114, respectively, and a plurality of sun gear teeth116. The thrust washer32can be received in the space between the first and second plate members50and52and can be disposed between the first thrust surface112on the sun gear22and the first plate member50. The second thrust surface114on the sun gear22can be disposed adjacent an associated thrust surface on the plate body100on the thrust plate34. Accordingly, the thrust washer32accommodates thrust forces between the sun gear22and the carrier body40in a first direction along the central axis54, while the plate body100accommodates thrust forces between the sun gear22and the carrier body40in a second, opposite direction along the central axis54.

Each of the planet gears24is disposed between the first and second plate members50and52and is rotatably received on an associated one of the pins42. In the example provided, needle bearings120are received between the pins42and the planet gears24and thrust washers122are received on the pins42between the first and second plate members50and52and respective axial ends of the planet gears24. The planet gears24can be meshingly engaged to the sun gear22and the ring gear14(FIG. 2).

The present disclosure also provides a method for assembling a planetary transmission10. The method includes: providing a carrier body40that defines a central axis54; assembling pins42and planet gears24to the carrier body40, each of the planet gears24being disposed about an associated one of the pins42, each of the pins42having a longitudinal pin axis84and a stepped axial end90that defines first and second axial end surfaces92and94, respectively, that are spaced apart from one another along the longitudinal pin axis84; inserting a sun gear22through an assembly aperture74in the carrier body40; abutting a thrust plate34to the carrier body40, the thrust plate having a plate body100and a plurality of tabs102that extend radially outwardly from the plate body100, each of the tabs102overlying the second axial end surface94of an associated one of the pins42; and mounting a retaining ring36through the assembly aperture74and into a retaining ring groove76formed in the carrier body40to retain the thrust plate34to the carrier body40.