JP4867430B2 - Planetary gear unit - Google Patents

Description

  The present invention relates to a planetary gear unit.

  Conventionally, in a transmission, for example, an automatic transmission, a power transmission path in a transmission including a planetary gear unit as a plurality of rotating units is switched by engaging / disengaging a clutch, a brake, etc., and a gear ratio is changed. Shifting is performed to achieve a plurality of shift speeds. In addition, hydraulic servos are provided to disengage and disengage the clutches, brakes, etc., and by supplying oil of a predetermined hydraulic pressure to the respective hydraulic servos, the clutches, brakes, etc. are engaged, By draining the oil, the clutch, brake, etc. can be released.

  The planetary gear unit includes a sun gear, a ring gear arranged to be rotatable relative to the sun gear in a radially outward direction of the sun gear, and a carrier arranged to be rotatable relative to the sun gear and the ring gear. . The carrier includes a carrier case, and pinion shafts are attached to a plurality of locations of the carrier case, and the pinions are rotatably arranged with respect to the pinion shaft via a plurality of needle rollers.

  By the way, when the planetary gear unit is operated to transmit rotation to another member through the carrier, to input rotation into the carrier, or to output rotation from the carrier, a large load is applied to the pinion shaft. Join.

  Therefore, it is conceivable to heat-treat the pinion shaft and the carrier case to prevent wear on the surface where the pinion shaft and each needle roller are in contact and the surface where the pinion shaft and the carrier case are in contact. When heat treatment is performed on the carrier case, cracks may occur in the flange portion of the carrier case. In addition, due to the heat treatment, in the carrier case, the diameter of the shaft hole for fitting the pinion shaft changes, or distortion (distortion) occurs, resulting in low pinion support accuracy. End up. Therefore, heat treatment is performed only on the pinion shaft.

  However, in the conventional planetary gear unit, when the pinion shaft is attached to the carrier case, a shaft hole is formed in the carrier case, the pinion shaft is inserted into the shaft hole, and the rotation of the pinion shaft is stopped by a stop pin. Therefore, play is generated between the carrier case and the pinion shaft as a load is applied to the pinion shaft. However, as described above, only the pinion shaft is heat-treated, and the carrier case is not heat-treated, so that the carrier case is worn due to the hardness difference. As a result, the durability of the planetary gear unit is reduced.

  An object of the present invention is to provide a planetary gear unit capable of solving the problems of the conventional planetary gear unit and improving the durability.

  Therefore, in the planetary gear unit of the present invention, a sun gear that is rotatably arranged, a ring gear that is rotatably arranged relative to the sun gear radially outward of the sun gear, and the sun gear and the ring gear. And a carrier supported in a cantilevered manner by the sun gear on one end side of the sun gear.

The carrier is rotatably disposed and has a shaft hole, a carrier case that is not subjected to heat treatment, a fitting portion that is not subjected to heat treatment at both ends, and a body that is heat-treated between the fitting portions. A pinion shaft provided with a portion, and a pinion rotatably arranged with respect to the pinion shaft.
The pinion shaft is inserted into the shaft hole at each insertion portion, and supports the pinion at the main body portion.
And the hardness of the said main-body part is higher than the hardness of each insertion part, and the hardness difference of a main-body part and each insertion part is made larger than the hardness difference of each insertion part and each shaft hole.

  According to the present invention, in the planetary gear unit, a sun gear that is rotatably arranged, a ring gear that is rotatably arranged relative to the sun gear radially outward of the sun gear, and the sun gear and the ring gear And a carrier supported in a cantilevered manner by the sun gear on one end side of the sun gear.

The carrier is rotatably disposed and has a shaft hole, a carrier case that is not subjected to heat treatment, a fitting portion that is not subjected to heat treatment at both ends, and a body that is heat-treated between the fitting portions. A pinion shaft provided with a portion, and a pinion rotatably arranged with respect to the pinion shaft.
The pinion shaft is inserted into the shaft hole at each insertion portion, and supports the pinion at the main body portion.
And the hardness of the said main-body part is higher than the hardness of each insertion part, and the hardness difference of a main-body part and each insertion part is made larger than the hardness difference of each insertion part and each shaft hole.

  In this case, since the hardness difference between the insertion portion and the shaft hole is reduced, it is possible to prevent the carrier case from being worn on the inner peripheral surface of the shaft hole. As a result, the durability of the planetary gear unit can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view of a planetary gear unit according to an embodiment of the present invention, and FIG. 2 is a schematic view showing a main part of a transmission according to the embodiment of the present invention.

  In the figure, reference numeral 11 denotes a planetary gear unit as a differential rotating element and as a rotating unit. The planetary gear unit 11 includes a sun gear S as a first rotating element that is rotatably arranged, and the sun gear S. Ring gears R1 and R2 as second and third rotating elements disposed so as to be rotatable relative to the sun gear S in the radially outward direction, and relatively rotatable with respect to the sun gear S and the ring gears R1 and R2. And a carrier CR as a fourth rotation element and as a support member. The ring gear R1 is formed by a small diameter gear, and the ring gear R2 is formed by a large diameter gear.

  The carrier CR is attached to the front carrier 21, the front carrier 21, a cup-shaped carrier cover 22 supported by the front carrier 21, and the carrier cover 22. A cup-shaped rear carrier 23 supported by the carrier 21 is provided. The front carrier 21, the carrier cover 22 and the rear carrier 23 are all formed by pressing stainless steel and constitute a carrier case 30.

  The front carrier 21 extends in the axial direction and is disposed so as to protrude forward (rightward in the drawing), and one end of the boss 24, that is, the rear end It has a disk-like flange portion 25 formed radially outward from the left end in the figure. The peripheral edge of the front opening of the carrier cover 22 is attached to the outer peripheral edge of the flange portion 25, and the peripheral edge of the front opening of the rear carrier 23 is the rear (left in the figure) opening of the carrier cover 22. Attached to the periphery.

  Stainless steel pinion shafts 18, 19 as first and second shaft members are attached to a plurality of locations in the circumferential direction on the radially inner side and the radially outer side of the carrier CR, and the pinion shafts 18, 19 On the other hand, pinions P1 and P2 as first and second rotating bodies are rotatably arranged.

  For this purpose, first and second insertion portions for inserting one end of each pinion shaft 18, 19, that is, the front end (right end in the figure), on the radially inner side and the radially outer side of the flange portion 25. Shaft holes 28 and 29 are formed, and at the bottom 31 of the carrier cover 22, a shaft hole 33 is formed as a third inserted portion for inserting the other end of the pinion shaft 19, that is, the rear end. The bottom portion 34 of the rear carrier 23 is formed with a shaft hole 35 as a fourth fitting portion for fitting the other end of the pinion shaft 18, that is, the rear end. In order to prevent the pinion shaft 18 from rotating relative to the front carrier 21 and the rear carrier 23, the pinion shaft 18 is prevented from rotating by a stop pin (not shown). For this purpose, a hole 71 is formed in the flange portion 25 for screwing the locking pin.

  The pinion P1 is formed of a long pinion, and meshes with the sun gear S radially inward, and meshes with the ring gear R1 and pinion P2 radially outward. The pinion P2 is a short pinion and is meshed with the ring gear R2 radially outward.

  In order to rotatably arrange the pinion P1 with respect to the front carrier 21 and the rear carrier 23, a washer w1 is provided between the front end of the pinion P1 and the flange portion 25, and between the rear end and the bottom portion 34 of the pinion P1. A washer w2 is a needle roller b1 between the front half of the pinion shaft 18 (right half in the drawing) and the pinion P1, and a needle roller b1 is a needle between the latter half of the pinion shaft 18 (left half in the drawing) and the pinion P1. A roller b2 is disposed.

  In order to rotatably dispose the pinion P2 with respect to the front carrier 21 and the carrier cover 22, a washer w3 is provided between the front end of the pinion P2 and the flange portion 25, and the rear end and the bottom 31 of the pinion P2. The washer w4 is disposed between the front half of the pinion shaft 19 and the pinion P2, and the needle roller b4 is disposed between the rear half of the pinion shaft 19 and the pinion P2.

  A clutch Ca as a friction engagement element is disposed on the outer side in the radial direction of the ring gear R1. The clutch Ca includes an outer thin plate 43 as a first friction material, an inner thin plate 44 as a second friction material, and the like. A spline formed on the outer peripheral surface of the ring gear R1 and an inner peripheral surface of the inner thin plate 44 are provided. The splines formed in the are engaged with each other. Therefore, the ring gear R1 also serves as the hub of the clutch Ca.

  Further, a clutch Cb as a friction engagement element is disposed on the radially outer side of the ring gear R2. The clutch Cb includes an outer thin plate 45 as a first friction material, an inner thin plate 46 as a second friction material, etc., and a spline formed on the outer peripheral surface of the ring gear R2 and an inner peripheral surface of the inner thin plate 46. The splines formed in the are engaged with each other. Therefore, the ring gear R2 also serves as the hub of the clutch Cb.

  Further, 51 is an input shaft, 53 is a sun gear shaft as a sleeve rotatably disposed outside the input shaft 51, and a spline 54 is formed on the outer peripheral surface of the front end of the sun gear shaft 53. The sun gear S is formed on the outer peripheral surface of the rear end. An oil hole 55 formed in the axial direction is formed in the input shaft 51, and the oil in the oil hole 55 is supplied radially outward through an oil groove 56 formed in the radial direction. The sun gear shaft 53 is also formed with oil grooves 58 in a plurality of locations in the radial direction, and the oil supplied from the oil grooves 56 is further supplied radially outward through the oil grooves 58.

  The pinion P1 and the pinion shaft 18 have long axial dimensions, making it difficult to supply oil to the needle rollers b1 and b2. Therefore, an oil passage 67 is formed extending in the axial direction at the center of the pinion shaft 18, and an oil groove 68 is formed in the radial direction in the central portion of the pinion shaft 18 in the axial direction. The front end of the oil passage 67 communicates with an oil passage 69 formed in the flange portion 25.

  Accordingly, the oil supplied between the sun gear shaft 53 and the boss portion 24 via the oil groove 58 is supplied between the pinion shaft 18 and the pinion P1 via the oil passages 69 and 67 and the oil groove 68. The needle rollers b1 and b2 are lubricated.

  In front of the carrier CR, a ring gear flange 62 is disposed adjacent to the flange portion 25, and the front end of the ring gear R2 is fixed to the outer peripheral edge of the ring gear flange 62. Further, a ring gear flange 63 is disposed behind the carrier CR so as to be adjacent to the bottom portion 34, and the rear end of the ring gear R 1 is fixed to the outer peripheral edge of the ring gear flange 63.

  A one-way clutch F is disposed in front of the ring gear R2, and the one-way clutch F includes an outer race 64 and an inner race 65, and the outer race 64 is fixed to the front end of the ring gear R2.

  By the way, when the planetary gear unit 11 is operated to transmit the rotation to another member via the carrier CR, to input the rotation to the carrier CR, or to output the rotation from the carrier CR, the pinion shaft 18 , 19 is subjected to a large load.

  In this case, the pinion shafts 18 and 19 and the carrier case 30 are heat treated to increase the hardness, and the surface where the pinion shafts 18 and 19 and the needle rollers b1 to b4 are in contact with each other, and the pinion shafts 18 and 19 and the carrier case 30 Although it is conceivable to prevent the wear contact surface from being worn, if the carrier case 30 is heat treated, the flange portion 25 may be cracked. Further, the diameter of the shaft holes 28, 29, 33, and 35 is changed by the heat treatment, or the carrier case 30 is distorted, so that the support accuracy of the pinions P1 and P2 is lowered. Therefore, only the pinion shafts 18 and 19 are subjected to heat treatment.

  Next, a heat treatment method for performing heat treatment only on the pinion shafts 18 and 19 will be described. In this case, since the structure of the pinion shafts 18 and 19 is the same, only the pinion shaft 18 will be described.

  FIG. 3 is a diagram showing a heat treatment method for the pinion shaft in the embodiment of the present invention. 3A is a reference diagram of the heat treatment method, and FIG. 3B is a diagram showing the heat treatment method in the present embodiment.

  In the figure, 18 is a pinion shaft, pt1 is a main body portion extending in the longitudinal direction of the pinion shaft 18, pt2 is a front end portion of the pinion shaft 18, pt3 is a rear end portion of the pinion shaft 18, and the main body portion pt1 is , Formed between the front end pt2 and the rear end pt3. The front end portion pt2 constitutes a fitting portion when the pinion shaft 18 is fitted into the shaft hole 28 (FIG. 1), and the rear end portion pt3 constitutes a fitting portion when the pinion shaft 18 is fitted into the shaft hole 35.

  By the way, as described above, when the pinion shaft 18 is attached to the carrier case 30, the pinion shaft 18 is fitted into the shaft holes 28 and 35 of the carrier case 30, and the pinion shaft 18 is prevented from rotating by the stop pin. Therefore, backlash is generated between the carrier case 30 and the pinion shaft 18 as a load is applied to the pinion shaft 18.

  In particular, the carrier CR is cantilevered in the radial direction by a sun gear shaft 53, the carrier cover 22 is supported by the front carrier 21, and the rear carrier 23 is supported by the front carrier 21 through the carrier cover 22. It has a structure. Therefore, when power is transmitted between the ring gear R1 and the pinion P1, if a force that shifts the axis on the rear half side of the pinion P1 in the circumferential direction with respect to the axis on the front half side acts, 18 is twisted about the sun gear shaft 53, and deformation occurs. Moreover, the pinion P1 is constituted by a long pinion, and the support span by the pinion shaft 18 is long. As a result, a large load is applied to the front end of the pinion shaft 18 between the inner peripheral surface of the shaft hole 28 and the outer peripheral surface of the front end of the pinion shaft 18, and rattling occurs between the front carrier 21 and the pinion shaft 18. End up.

  Therefore, as shown in FIG. 3A, when the entire pinion shaft 18 is subjected to heat treatment, the surfaces of the main body part pt1, the front end part pt2, and the rear end part pt3 (parts indicated by hatching) However, when the front end portion pt2 and the rear end portion pt3 are inserted into the shaft holes 28 and 35, the carrier case 30 is not heat-treated, so that the hardness of the front end portion pt2 and the rear end portion pt3 with increased hardness is increased. The outer peripheral surface comes into contact with the inner peripheral surfaces of the shaft holes 28 and 35 whose hardness is not increased.

  As a result, the carrier case 30 is worn on the inner peripheral surfaces of the shaft holes 28 and 35 due to the hardness difference, so that the durability of the planetary gear unit 11 is lowered.

  However, in the present embodiment, as shown in FIG. 3B, the entire pinion shaft 18 is not subjected to heat treatment, and a portion other than the front end portion pt2 and the rear end portion pt3, that is, the main body portion pt1. Is subjected to heat treatment. That is, the surface of the main body portion pt1 (the portion indicated by hatching) is cured, while the surfaces of the front end portion pt2 and the rear end portion pt3 are not cured. As a result, the hardness of the main body part pt1 is made higher than the hardness of the front end part pt2 and the rear end part pt3, and the hardness difference between the main body part pt1, the front end part pt2 and the rear end part pt3 is the front end part pt2 and the rear end part. The hardness difference between the portion pt3 and the shaft holes 28 and 35 is made larger.

  In this case, the main body portion pt1 forms a heat treatment region, and the front end portion pt2 and the rear end portion pt3 form a non-heat treatment region.

  Therefore, when the front end portion pt2 and the rear end portion pt3 are fitted into the shaft holes 28 and 35, the difference in hardness is reduced even if the carrier case 30 is not heat-treated. Therefore, it is possible to prevent the carrier case 30 from being worn on the inner peripheral surfaces of the shaft holes 28 and 35. As a result, the durability of the planetary gear unit 11 can be improved.

  In addition, even if distortion occurs in the main body part pt1 by applying heat treatment to the main body part pt1, only the surface of the main body part pt1 is cured. Therefore, the surface is finished by finishing, and the pinion P1 , P2 support accuracy can be increased.

  In the present embodiment, the heat treatment is performed by induction hardening, and induction hardening is performed on the pinion shaft 18 with the front end portion pt2 and the rear end portion pt3 masked, and then the mask is removed.

  In the present embodiment, only the main body part pt1 is heat-treated, and the hardness of the main body part pt1 is made higher than the hardness of the front end part pt2 and the rear end part pt3, but only the front end part pt2 and the rear end part pt3. Is subjected to heat treatment so that the hardness of the front end portion pt2 and the rear end portion pt3 is lower than the hardness of the main body portion pt1, and the difference in hardness between the front end portion pt2 and the rear end portion pt3 and the shaft holes 28 and 35 is reduced or eliminated. be able to.

  In addition, this invention is not limited to the said embodiment, It can change variously based on the meaning of this invention, and does not exclude them from the scope of the present invention.

It is sectional drawing of the planetary gear unit in embodiment of this invention. It is the schematic which shows the principal part of the transmission in embodiment of this invention. It is a figure which shows the heat processing method of the pinion shaft in embodiment of this invention.

Explanation of symbols

11 Planetary gear unit 18, 19 Pinion shaft 28, 29, 33, 35 Shaft hole CR Carrier P1, P2 Pinion pt1 Main part pt2 Front end pt3 Rear end

Claims (2)

A sun gear arranged rotatably,
A ring gear disposed so as to be rotatable relative to the sun gear at a radially outer side of the sun gear;
Is disposed to freely rotate relative to the sun gear and the ring gear, and one end side of the sun gear, which has a carrier which is supported in shape has the result piece sun gear,
The carrier is rotatably disposed and has a shaft hole, a carrier case that is not heat-treated, a fitting portion that is not heat-treated at both ends, and a body portion that is heat-treated between the fitting portions. A pinion shaft provided, and a pinion rotatably arranged with respect to the pinion shaft,
The pinion shaft is inserted into the shaft hole in each insertion portion, and supports the pinion in the main body portion,
The planetary gear unit characterized in that the hardness of the main body portion is higher than the hardness of each insertion portion, and the hardness difference between the main body portion and each insertion portion is larger than the hardness difference between each insertion portion and each shaft hole. .   The planetary gear unit according to claim 1, wherein the heat treatment is performed by induction hardening.

Images