JP2009008139A - Radial needle roller bearings - Google Patents

Abstract

A needle roller bearing having high reliability while using a resin material is provided.
When a groove 52d is provided on the outer periphery of an annular portion 52a, lubricating oil easily accumulates in the groove 52d, the formation of an oil film on the guide surface is promoted by the lubricating oil, and a cooling effect of the heat generating portion can be obtained. Further, by providing the groove 52d, the contact area between the annular portion 52a and the outside air increases, and a heat dissipation effect can be expected. In the present embodiment, by adopting measures against such heat generation, it is possible to provide a radial needle roller bearing that can cope with high-speed rotation while reducing drag torque using a resin material.
[Selection] Figure 4

Description

  The present invention relates to a radial needle roller bearing used in, for example, a planetary gear mechanism of an automatic transmission for a vehicle, and particularly suitable for a short pinion of a single pinion planetary gear mechanism, a double pinion planetary gear mechanism, and a Ravigneaux planetary gear mechanism. The present invention relates to a radial needle roller bearing.

  A planetary gear mechanism is generally used for an automatic transmission mounted on a vehicle or the like, and a planetary pinion configured with a pinion gear, a shaft fixed to a carrier and a planetary needle bearing transmits torque, and the shaft It performs a combined motion of a rotating motion that rotates around and a revolving motion that rotates around the sun gear together with the carrier (see Patent Document 1).

  A “helical gear” is generally used as a planetary gear. A radial load and an axial load are generated along with a tangential force, and the axial load acts as a moment load on the bearing.

At present, automatic transmissions, the mainstream of which is the fourth speed, tend to be multistaged from the fifth speed to the seventh speed, and the trend of higher torque and compactness is achieved. In addition, there is a fact that it is required to handle a large moment load. In addition, from the viewpoint of improving fuel efficiency, there is a demand for further reducing the drag resistance of the lubricating oil and suppressing drag torque.
JP 2006-132610 A

  On the other hand, drag torque can be suppressed by using a resin cage. However, as described above, in the radial needle roller bearing used in the planetary gear mechanism, since the centrifugal force acting on the revolution in addition to the high speed rotation acts on the cage, the heat generated by the friction between the cage and the guide surface becomes excessive. , The strength of the cage is reduced due to the deterioration of the resin due to the temperature rise, and in some cases, the cage may be damaged.

  The present invention has been made in view of such problems, and an object thereof is to provide a highly reliable needle roller bearing while using a resin material.

The radial needle roller bearing of the present invention is a radial needle roller bearing having a roller and a cage that holds the roller.
The retainer is formed of a resin material, and includes a pair of annular portions and a plurality of column portions connecting the annular portions in the axial direction, and a groove extending in the circumferential direction is formed on an outer periphery of the annular portion. It is formed.

  According to the radial needle roller bearing of the present invention, since the cage is formed of a resin material, the weight can be reduced and drag torque can be suppressed. In addition, since a groove extending in the circumferential direction is formed on the outer periphery of the annular portion, when the outer periphery of the annular portion is used as a guide surface, the friction of the guide surface is reduced by the lubricating oil retained in the groove. , Heat generation can be suppressed, and deterioration of the resin of the cage can be suppressed.

  The radial needle roller bearing is preferably disposed between a pinion shaft and a pinion gear in the planetary gear mechanism.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing a part of a vehicle automatic transmission including a radial needle roller bearing according to the present embodiment.

  In FIG. 1, an input shaft 11 that constitutes an input member that transmits a turbine output rotation of a torque converter (not shown) to a planetary gear set 12 in a case 10 is disposed on the front sun gear 13 side of the planetary gear set 12. The counter drive gear 14 is disposed on the rear sun gear 15 side of the planetary gear set 12 with the rear wall of the case 10 interposed therebetween. A sun gear shaft 20 constituting a support shaft of the planetary gear set 12 is disposed on the inner peripheral side of the planetary gear set 12. In this embodiment, this shaft is integrated with the rear sun gear 15, and the planetary gear set 12 and the counter drive gear are combined. 14 extending through.

  The input shaft 11 is supported by the case 10 and connected to the turbine of the torque converter, the respective clutches 16, 17, 18 and the first one-way clutch OC1. Specifically, the input shaft 11 is supported by a hollow stator shaft 19 fixed to the front wall of the case 10 constituted by an oil pump cover, near the front end portion via a bush, and near the rear end portion via a needle bearing. The front end is connected to a turbine hub (not shown) by spline engagement, and the inner end of the first one-way clutch OC1 is connected to the drum side hydraulic servo cylinder inner member 21 of each clutch 18, 17, 16 at the rear end. It is connected through.

  The sun gear shaft 20 has one end connected to the input shaft 11 via the clutch 18 and the first one-way clutch OC1, and the other end connected to the case via the brake 22 outside the counter drive gear 14. 10. Specifically, the sun gear shaft 20 is supported at the front end by a recess at the rear end of the input shaft 11 via a bush, and the vicinity of the rear end is supported by the inner periphery of the ring gear flange 23 via the bush and is fitted to the outer periphery thereof. The counter drive gear 14 is finally supported on the rear wall of the case 10 via a boss portion and a roller bearing. The front end side of the sun gear shaft 20 is connected to the hub 24 side of the clutch 18 by spline engagement. The rear end of the sun gear shaft 20 is connected to the hub 25 side of the brake 22 by spline engagement.

  In the planetary gear set 12, the front sun gear 13 and the carrier Q are supported by the sun gear shaft 20 via bushes, respectively, and the ring gear 26 is splined and connected to the member via a ring gear flange 23 connected to the member by spline engagement. By being fixed to the counter drive gear 14, as a result, it is supported on the rear wall of the case 10 via the ball bearing 27. The front sun gear 13 of the planetary gear set 12 is connected to the hub 28 side of the clutch 17, and the carrier Q is parallel to the hub 29 of the clutch 16, the hub 31 of the brake 30, and the inner race of the second one-way clutch OC2. It is connected.

  In this gear train, the clutch 17 that connects the input shaft 11 to the front sun gear 13, the clutch 17 that connects to the rear sun gear 15, and the clutch 16 that connects to the carrier Q respectively input the hydraulic servos and friction members of these clutches together. The shaft 11 and the sun gear shaft 20 are arranged on the outer periphery of the connecting portion. First, the clutch 17 includes an inner peripheral side member 21 that is rotatably fitted to the outer periphery of a boss portion 32 that extends from an oil pump cover that is bolted to an oil pump body that constitutes the front wall of the case 10, and an inner peripheral member 21. A hydraulic servo in which a piston 34 that also serves as a drum of the clutch 17 is fixedly engaged with an inner side surrounded by a drum 33 having a fixed peripheral side, and an inner peripheral side connected to the inner side of the inner periphery of the front end of the drum 33 and the front sun gear 13. The friction members 40 are spline-engaged and connected to the outer periphery of the hub 28 arranged in this manner.

  Next, the clutch 18 is fitted into a drum 34 that also serves as a piston of the clutch 17 and is slidably fitted into the inner circumferential member 21, and an inner cylinder surrounded by the inner circumferential member 21 and the drum 34. A hydraulic servo having a centrifugal hydraulic canceling chamber behind the piston 35, a front end inner periphery of the drum 34, and a hub disposed on the inner periphery thereof with the inner peripheral side connected to the input shaft 11. And a friction member 36 that is spline-engaged to the outer periphery of 24. The outer race of the first one-way clutch OC1 is fixed to the hub 24 of the clutch 18.

  The clutch 16 is configured such that the drum 33 of the clutch 17 is a piston, and a piston 37 that is fitted over the piston is connected to the drum 38, and includes a hydraulic servo including a centrifugal hydraulic pressure canceling chamber, and the planetary gear set 12. The outer periphery of the hub 29 connected to the inner race of the second one-way clutch OC2 riveted to the carrier Q and the friction member 39 connected to the inner periphery of the drum 38 by spline engagement.

  In the hydraulic servo of each clutch arranged in this way, the inner peripheral member 21 common to each clutch, the member 33 serving as the drum of the clutch 17 and the piston of the clutch 16 are fixed in the axial direction. The drum 34 and the piston 35 are axially movable members 18. Accordingly, the supply of servo hydraulic pressure from the oil passage of the boss portion 32 causes the clutch 17 to engage the friction member 40 between its own drum 33 and the drum 34 of the clutch 18. The friction force is held between the drum 35 and the piston 35 by pushing the piston 35 of the clutch 17 between the drum 35 and the piston 35. By advancing the drum 38 in the axial direction with respect to the drum 33 of the clutch 17, the friction member 39 is sandwiched and engaged between them.

  Next, the brake 30 includes a hydraulic servo built in the rear wall of the case 10, a hub 31 extending from the inner race of the second one-way clutch OC2, and a friction member 42 splined to the peripheral wall of the case 10. The friction member 42 is disposed on the radially outer side of the ring gear 26 of the planetary gear set 12. In the second one-way clutch OC2 arranged in parallel with this, the inner race is riveted to the carrier Q of the planetary gear set 12 as described above, and the outer race is spline-engaged with the peripheral wall of the case 10 so that the diameter of the planetary gear set 12 is increased. It is arrange | positioned in the substantially axial center part of the direction outer side.

  The brake 22 is disposed outside the rear wall of the case 10, and is spline-engaged with a cover 10 a covering the counter gear pair disposed there and a hub 25 fixed to the rearmost portion of the sun gear shaft 20. The friction member 43 is arranged behind the counter gear pair and a hydraulic servo built in the rear wall of the case 10.

  When the first speed (1st) is selected in this gear train, the rotation from the input shaft 11 is input to the front sun gear 13 via the clutch 17, and the reaction force is exerted on the carrier Q locked by the engagement of the second one-way clutch OC2. Then, the reduced rotation of the maximum reduction ratio output to the ring gear 26 is transmitted to the ring gear of the sub-transmission unit through the counter gear pair, and is transmitted from the differential device (not shown) to the driving wheel of the vehicle.

  Next, in the second speed (2nd), rotation is also input from the input shaft 11 to the front sun gear 13 via the clutch 17, and a reaction force is applied to the rear sun gear 15 locked by engagement of the brake 22. Is output at reduced speed. This rotation is input to the ring gear of the auxiliary transmission unit, and is transmitted from a differential device (not shown) to the drive wheels of the vehicle.

  The third speed (3rd) is the same as the second speed on the main shaft side, and is achieved by engaging the clutch on the countershaft side. In this case, the rotation from the main transmission unit is transmitted from the differential device (not shown) to the drive wheels of the vehicle through the planetary gear directly connected by the engagement of the clutch.

  Further, in the fourth speed (4th), the planetary gear set 12 on the main transmission unit side and the planetary gear on the auxiliary transmission unit side are both directly connected, and the input rotation of the input shaft 11 is not decelerated by the counter gear pair. It is transmitted to a drive wheel of a vehicle from a differential device (not shown).

  FIG. 2 is a cross-sectional view showing the periphery of the pinion shaft of the planetary gear set using the radial needle roller bearing according to the present embodiment. FIG. 3 is a perspective view of the cage of the needle roller bearing according to the present embodiment. As shown in FIG. 2, the needle roller bearing 50 includes a roller 51 and a cage 52 that holds the roller 51. The needle roller bearing 50 is disposed around a pinion shaft C attached to the carrier Q and rotates the pinion P <b> 1. Supports freely. In the pinion shaft C, a bag hole Ca extending along the axis from the right end surface of FIG. 2, and extending in the radial direction from the middle of the bag hole Ca, is located in the center of the roller 51 on the peripheral surface of the pinion shaft C. A diameter hole Cb is formed so as to be opposed to each other. The needle roller bearing 50 is lubricated by lubricating oil supplied from the outside of the pinion shaft C through the bag hole Ca and the diameter hole Cb. A washer WS is disposed between the carrier Q and the pinion P1.

  As shown in FIG. 3, the retainer 52 is integrally formed from a resin material and has a configuration in which a pair of annular portions 52a and 52a are connected by a plurality of column portions 52b. A pocket 52p for holding the roller 51 is formed between the adjacent column portions 52b. On the outer periphery of each annular portion 52a, two grooves 52d and 52d having a U-shaped cross section (or V-shape) extending in the circumferential direction are formed. The cage 52 of the present embodiment is of an outer ring guide type (guided while the annular portions 52a and 52a slide relative to the inner periphery of the pinion P1). Let the outer periphery of the annular part 52a be a guide surface.

  FIG. 4 is a cross-sectional view around the annular portion of the cage of the present embodiment. FIG. 5 is a cross-sectional view around the annular portion of the cage according to the comparative example. The holder 52 'of the comparative example has the same configuration as the holder 52 except that the groove is not provided in the annular portion 52a. In the comparative example shown in FIG. 5, friction is generated between the pinion P1 and the annular portion 52a of the cage 52 'due to the upward centrifugal force in the figure, and heat is generated. In particular, during high-speed rotation, the amount of heat generation increases due to poor oil film formation on the guide surface and an increase in the sliding speed of the pinion P1 and the retainer 52 ', and this was used in the planetary gear mechanism as in this embodiment. In this case, since revolution is also applied, a strong centrifugal force is generated and the surface pressure increases, so that heat generation becomes more remarkable. Therefore, when a synthetic resin is used for the cage 52 ', the temperature of the cage 52' is excessively increased due to the heat generation, thereby causing deterioration of the resin, reducing the strength, and possibly damaging the cage 52 '. It will cause.

  On the other hand, as shown in FIG. 4, when the groove 52d is provided on the outer periphery of the annular portion 52a, the lubricating oil easily accumulates in the groove 52d, the formation of an oil film on the guide surface is promoted by the lubricating oil, and the heat generating portion The cooling effect can be obtained. Further, by providing the groove 52d, the contact area between the annular portion 52a and the outside air increases, and a heat dissipation effect can be expected. In the present embodiment, by adopting measures against such heat generation, it is possible to provide a radial needle roller bearing that can cope with high-speed rotation while reducing drag torque using a resin material.

  The reason why the groove 52d is in the circumferential direction is that it is the best mode that has the least influence on the rotational direction. For example, a plurality of grooves extending in the axial direction can be provided on the outer periphery of the annular portion 52a. However, since a gap is formed in the rotation direction, smooth rotation is hindered, and repetitive stress is applied to the uneven portion of the groove. Is generated, and the strength is easily reduced.

  As the synthetic resin material used in the cage according to the present embodiment, it is preferable to use polyamide or polyphenylene sulfide in consideration of strength and heat resistance in addition to self-lubricity, but this is not restrictive.

  The present invention has been described with reference to the embodiments. However, the present invention should not be construed as being limited to the above-described embodiments, and can be modified or improved as appropriate. The present invention is not limited to the Ravigneaux type planetary gear mechanism, and can be applied to needle roller bearings and pinion shafts used in other types of planetary gear mechanisms.

1 is a partial cross-sectional view of a vehicle automatic transmission 1 including a radial needle roller bearing according to a first embodiment. It is sectional drawing which shows the pinion shaft periphery of the planetary gear set containing the radial needle roller bearing concerning 1st Embodiment. It is a perspective view of the retainer of the needle roller bearing concerning this embodiment. It is sectional drawing of the annular part periphery of the holder | retainer of this Embodiment. It is sectional drawing of the annular part periphery of the holder | retainer concerning a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Case 10a Cover 11 Input shaft 12 Planetary gear set 13 Front sun gear 14 Counter drive gear 15 Rear sun gear 16 Clutch 17 Clutch 18 Clutch 19 Stator shaft 20 Sun gear shaft 21 Inner peripheral member 22 Brake 23 Ring gear flange 24 Hub 25 Hub 26 Ring gear 27 Ball bearing 28 Hub 29 Hub 30 Brake 31 Hub 32 Boss 33 Drum 33 Member 34 Drum 35 Piston 36 Friction Member 37 Piston 38 Drum 39 Friction Member 40 Friction Member 42 Friction Member 43 Friction Member 50 Needle Roller Bearing 51 Roller 52 Cage C Pinion Shaft OC1 One-way clutch OC2 One-way clutch P1 Pinion gear Q Carrier

Claims (2)

In a radial needle roller bearing having a roller and a cage for holding the roller,
The retainer is formed of a resin material, and includes a pair of annular portions and a plurality of column portions connecting the annular portions in the axial direction, and a groove extending in the circumferential direction is formed on an outer periphery of the annular portion. A radial needle roller bearing characterized by being formed.   The radial needle roller bearing according to claim 1, wherein the radial needle roller bearing is disposed between a pinion shaft and a pinion gear in a planetary gear mechanism.

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