Abstract
A planetary carrier assembly pinion for a planetary gear system includes a pinion planetary carrier having first and second sections which extend radially, each planetary gear rotatably mounted on a pinion shaft via a bearing a first thrust washer disposed between an axial end of each planet pinion and the first section and a second thrust washer disposed between the other axial end of each planet pinion and the second section. The first and second thrust washers each have a surface hardness large enough to ensure a better durability and reliability.
Description
DESCRIPTION OF THE PREFERRED EMBODIMENTA preferred embodiment of a set of planetary-gear carrier for a planetary gear system for use in an automatic transmission according to the present invention will be described with reference to FIG. 1.In the figure. 1, a set of planet pinion carrier designated generally by reference numeral 10 includes a planetary-gear carrier which is also generally designated by the reference numeral 12. The pinion carrier 12 has a rotational axis x and includes a first section 12a which extends radially relative to the rotation axis x and a second section 12b extending radially and spaced a predetermined distance from the first section 12a in the direction for receiving axial planetary gear 14 therebetween. The first and second pinion carrier sections 12 are fixedly connected together and fixedly support each of the pinion shafts 16 therebetween. Each pinion 14 is rotatably mounted on the corresponding pinion shaft 16 through a needle roller bearing 18. A pair of thrust washers 20 and 21 are arranged axially in sliding contact with each other between an axial end surface of the pinion 14 and the first section 12a, and another pair of thrust washers 22 and 23 are also arranged axially in sliding contact with each one another between the other axial end surface of the pinion 14 and the second section 12b, to support the axial load applied thereto. Thrust washers 20 and 22 are the same members each facing the corresponding axial end surface of the pinion 14, and each being formed by the application of boron to an immersion process tool steel high carbon to provide surface hardness of not less than 700 Hv, preferably 700 to 1500 Hv, and a hardness internal or within not more than 350 Hv, preferably 200 to 350 Hv. The surface hardness of not less than Hv 700 extends through a maximum thickness of 60 m on the surfaces of each of the thrust washers 20 and 22. Moreover, the thrust washers 21 and 23 are the same members each facing the corresponding first or second section 12a or 12b, and each being formed of a copper alloy material. The thrust washer 21 has a pawl 21a at its outer periphery which fits into a recess 12c formed in a corresponding portion of the first section 12a to prevent rotation of the thrust washer 21. Similarly, the thrust washer 23 has a pawl 23a its outer periphery which engages in a recess 12d formed in a corresponding portion of the second section 12b for preventing rotation of the thrust washer 23.An annular groove 24 is formed on the inner periphery of the first section 12a and a conduit 26 is formed lubricant further in the first section 12a. The lubricant line 26 extends radially outward from the annular groove 24 to communicate with a lubricant passage 28 formed through the pinion shaft 16. The lubricant passage 28, in turn, opens to the rolling contact surfaces of the rolling elements of needles 18.A gear 30 has a central section 32 which receives a rotation axis thereof to be securely connected thereto wearing, and meshes with the planetary gears 14. A ring gear 34 is further provided around the planetary pinions 14 and meshes with it, while the pinion carrier 12 has a hub portion 36 for receiving a rotation shaft to be firmly connected thereto. In this embodiment, the planetary gear 30, the planetary gears 14 and ring gear 34 are all helical gears. The sun gear 30 is formed with a lubricant passage 38 for carrying out the lubricant supplied via a lubricating circuit formed in the rotation axis associated annular groove 24.An annular bearing race 40 is disposed on a left side of the first section 12a in Fig. 1. The raceway 40 receives the rolling elements on a thrust bearing 42 which is supported by a radial extension 44 of the gear 30.Now, the operation of the above preferred embodiment is described below.When the planetary gears 14 are rotated, since the helical gears are used as mentioned above, a thrust load applied to the thrust washers 20, 21 or the thrust washers 22, 23 depending on a direction of the Rotation of the planetary gears 14. Furthermore, the needle bearing 18 is also rotated to exert a load on the thrust washers 20 and 22 because of interference between the axial ends of the needle bearing 18 and associated thrust washers 20 and 22. However, since the thrust washers 20 and 22 each have a surface hardness of at least Hv 700 which is large enough to avoid abrasion, even when a large load is applied substantially to the thrust washers 20 and 22, the thrust washers 20 and 22 are not subject to substantial abrasion in a manner that ensures highly reliable durability. Furthermore, although it generates relative rotation between the thrust washers 20 and 21 and between the thrust washers 22 and 23, since the thrust washers 21 and 23 are formed each of the copper alloy materials having high lubricity, the thrust washers 21 and 23 are not subjected to abrasion due to sliding interference with the thrust washers 20 and 22.The lubricant is supplied to the thrust washers 20 and 23 for lubrication of the same. Specifically, the lubricant introduced through the lubricating circuit formed in the axis of rotation of the sun gear 30 is inserted into the annular groove 24 through the lubricant passage 38. The lubricant is, in turn, provided to the rolling surfaces of the needle bearings 18 through the lubricant passages 26 and 28. After lubricating the needle bearing 18, the lubricant supplied to the thrust washers 20 and 23 through the axial ends of the needle bearing 18.It is appreciated that the thrust washers 21 and 23 can be designed to have a hardness of not less than 700 Hv and the thrust washers 20 and 22. In this case, the 11th and the 13th ratchets can be eliminated to allow the rotation of the thrust washers 21 and 23. Also, it is possible to use only the thrust washers 20 and 22 and thrust washers remove end 21 23.It is understood that this invention is not limited to the embodiment described above, and that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGSThe present invention will be understood more fully from the detailed description given below and from the accompanying drawings of the preferred embodiment of the invention, which is given by way of example only, and are not intended to be limiting of the present invention.In the drawing:. Figure 1 is a longitudinal sectional view showing a set of planetary-gear carrier for a planetary gear system for use in an automatic transmission according to a preferred embodiment of the present invention.Background of the Invention1. Field of the InventionThis invention relates generally to a set of planetary-gear carrier for a planetary gear system for use in an automatic transmission and, more specifically, to the set of planet pinion carrier, wherein the thrust washers arranged between the axial ends of each planet pinion and planet gear carrier rotatably supporting the planet pinions have sufficient surface hardness to ensure durability and reliability.Two. Description of the Prior ArtA set of known planetary-gear carrier for a planetary gear system for use in an automatic transmission, as described in Japanese First (unexamined) Utility Model No. 62-40346.In this known structure, the support assembly includes a pinion planetary carrier having an axis of rotation, the planetary gears each rotatably mounted on a pinion shaft which is fixed to the pinion carrier, a bearing roller needle disposed between the planet gear and pinion shaft for rotatably supporting the planet gear and thrust washers. Specifically, the pinion carrier having first and second sections extending radially relative to the rotational axis and axially spaced by a predetermined distance from each other to receive the planet pinions therebetween. The first and second sections are fixedly connected to each other and fixedly support each of the pinion shafts therebetween. The planet pinion is rotatably mounted on each pinion shaft through the needle roller bearing. Further, a pair of thrust washers are disposed in sliding contact with each other between an axial end surface of each planet gear and the first section, and another pair of thrust washers are disposed in sliding contact with each other between the other end axial surface of each planet pinion and the second section, for axial loads applied to it from the planet gear and the needle bearing. Using two thrust washers disposed in sliding contact with each other, relative rotation speed between the two thrust washers when the planetary gears are rotated can be reduced in order to improve the durability of the thrust washers .In this set of planetary pinion carrier known, however, there is a problem that the durability of the thrust washers is insufficient when the applied load is large, that is, when the planetary gears are rotated at a high speed and a large torque. Specifically, in the known structure, each thrust washer is formed by applying a nitriding process for a steel soft high carbon tool having a surface hardness of about Hv (Vickers hardness) 400. Consequently, thrust washers, particularly those facing axial end surfaces of each planet gear are subject to abrasion when the applied load is large, due to contact with the axial ends of the needle roller bearing and due the load applied unevenly to the thrust washer, which is caused by the inclination of each planet pinion mounted.
SUMMARY OF THE INVENTIONAccordingly, it is an object of the present invention is to provide a planet-pinion carrier assembly for a planetary gear system which can remove the defects mentioned above inherent in the known structure.It is another object of the present invention is to provide a holder assembly for a planetary-pinion planetary gear system, wherein the thrust washers disposed between the axial end surfaces of each planet pinion and sections extending radially from a planet carrier pinion are formed hard enough to not be subject to abrasion to ensure durability and reliability of the friction discs.To achieve the above and other objects, according to one aspect of the present invention, a carrier assembly for a planetary-pinion planetary gear system comprises a planetary pinion carrier having an axis of rotation and includes a first section extending radially relative to the axis of rotation and a second section extending radially and axially spaced a predetermined distance from the first section, and planetary gears each rotatably mounted on a pinion shaft through means bearing, pinion shaft extending between the first and second sections with one end fixed to the first axial section and with its other end attached to the second axial section, the planet gears, each having a first axial end face to the first section and a second axial end opposite to the second section.Whole-pinion planetary carrier further includes a first thrust washer disposed between the first axial end of each planet pinion and the first section and a second thrust washer disposed between the second axial end of each planet pinion gear and the second section .The first and second thrust washers each are designed to have a surface hardness of not less than 700 Hv.According to another aspect of the present invention, a carrier assembly for a planetary-pinion planetary gear system, the support assembly including a planet pinion planetary pinion carrier having an axis of rotation and includes a first section extending radially relative to the axis of rotation and a second section extending radially and axially spaced a predetermined distance from the first section, the planetary gears each mounted rotatably on a pinion shaft by means of bearing, pinion shaft extending between the first and second sections with an axial end fixed to the first section and with its other end attached to the second axial section, the planet gears, each having a first axial end face to the first section and a second axial end opposite the second section, a first thrust washer disposed between the first axial end of each planet pinion and the first section and a second thrust washer disposed between the second axial end of each planet pinion and the second section, a method of forming each of the first and second thrust washers comprises applying an immersion process of boron to a base material to provide each of the first and second thrust washers, the first and second thrust washers each having a surface hardness of not less than 700 Hv.
0 comments:
Post a Comment