JP2013231494A - Thrust bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thrust bearing enabling reduction of wear of a bearing ring in the thrust bearing.SOLUTION: A thrust bearing includes a first bearing ring 11 having a first raceway surface 11a, a second bearing ring 12 having a second raceway surface 12a, a plurality of rolling elements 13 disposed rotatably between the first raceway surface 11a and the second raceway surface 12a, and a retainer 14 for retaining the plurality of rolling elements 13 circumferentially at substantially equal intervals, and is used in a hydraulic continuously variable transmission 30, and a contact surface 20 of the first bearing ring 11 or the second bearing ring 12 with which a nose piston 35 of the hydraulic continuously variable transmission 30 comes into contact is formed with a peripheral groove 21 with a cross section in an arc shape.

Description

  The present invention relates to a thrust bearing, and more particularly, to a thrust bearing used in a hydraulic continuously variable transmission (HST).

  In hydraulic equipment such as a hydraulic continuously variable transmission, a thrust bearing is used in a portion that receives piston pressure when converting the rotational force of the shaft into hydraulic pressure or when converting the hydraulic pressure into the rotational force of the shaft. .

  And as a thrust bearing used for the conventional hydraulic continuously variable transmission, the first raceway having the first raceway surface, the second raceway having the second raceway surface, the first raceway surface and the second raceway. A plurality of rolling elements that are arranged to freely roll between the surfaces, and a cage that holds the plurality of rolling elements at substantially equal intervals in the circumferential direction. What is comprised is known (for example, refer patent document 1).

JP 2008-215566 A

  However, in the thrust bearing described in Patent Document 1, since the contact surface of the raceway ring that contacts the nose piston of the hydraulic continuously variable transmission is formed in a flat shape, the contact surface between the nose piston and the contact surface of the raceway ring is formed. In some cases, slippage occurred in the meantime, causing wear on the race.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a thrust bearing capable of reducing wear of a bearing ring of the thrust bearing.

The above object of the present invention can be achieved by the following constitution.
(1) a first raceway having a first raceway surface, a second raceway having a second raceway surface, and a plurality of rolling elements arranged to be freely rollable between the first raceway surface and the second raceway surface; And a retainer that holds the plurality of rolling elements at substantially equal intervals in the circumferential direction. In a thrust bearing used in the hydraulic continuously variable transmission, the first piston that contacts the nose piston of the hydraulic continuously variable transmission A thrust bearing, wherein a circumferential groove having a circular arc cross section is formed on a contact surface of the raceway ring or the second raceway ring.
(2) The thrust bearing according to (1), wherein the radius of curvature of the circular arc of the circumferential groove / the radius of curvature of the curved surface of the tip of the nose piston is set to 1 or more and 10 or less.

  According to the thrust bearing of the present invention, the circumferential groove having the circular arc cross section is formed on the contact surface of the first raceway ring or the second raceway ring that contacts the nose piston of the hydraulic continuously variable transmission. The surface pressure with the wheel can be suppressed, and the wear of the raceway can be reduced.

1 is a cross-sectional view illustrating a hydraulic continuously variable transmission in which an embodiment of a thrust bearing according to the present invention is used. It is sectional drawing explaining the thrust bearing shown in FIG. It is a graph which shows the relationship between the curvature radius R1 of a circumferential groove, and the curvature radius R2 of a piston, and surface pressure ratio. It is sectional drawing explaining the modification of the thrust bearing shown in FIG.

  Hereinafter, an embodiment of a thrust bearing according to the present invention will be described in detail with reference to the drawings.

  A thrust ball bearing (thrust bearing) 10 of this embodiment is used in a hydraulic continuously variable transmission 30 shown in FIG. 1, and this hydraulic continuously variable transmission 30 is transmitted from an engine (not shown) to an input shaft 31. A variable displacement pump 32 that converts the rotational driving force into oil pressure, and a variable displacement motor 41 that returns the oil pressure to the rotational driving force and transmits it to the output shaft 40. Then, the hydraulic continuously variable transmission 30 changes the rotational driving force transmitted to the input shaft 31 steplessly to the driving force on the forward side and the backward side and outputs it from the output shaft 40, or stops the output. Or

  The variable displacement pump 32 includes a cylinder block 33 that rotates integrally with the input shaft 31, a nose piston 35 that is reciprocated in the piston chamber 34, and a guide surface of the guide block 36. And a swash plate 37 that rotates along the axis. The variable displacement pump 32 rotates the swash plate 37 to change the reciprocating stroke of the nose piston 35 and change the amount of oil discharged from the piston chamber 34. On the swash plate 37, the thrust ball bearing 10 is disposed at a position where it comes into contact with the tip of the nose piston 35, and the thrust ball bearing 10 rotates together with the swash plate 37.

  As shown in FIG. 2, the thrust ball bearing 10 includes a first race ring 11 having a first raceway surface 11a, a second race ring 12 having a second raceway surface 12a, a first raceway surface 11a and a second raceway. There are provided a plurality of balls (rolling elements) 13 that are arranged so as to roll freely between the surfaces 12a, and a cage 14 that holds the plurality of balls 13 at substantially equal intervals in the circumferential direction.

  One first race ring 11 is in contact with the tip of the nose piston 35, and the other second race ring 12 is fixed to the swash plate 37. For this reason, the thrust ball bearing 10 receives the high load received from the nose piston 35 by the first race ring 11 and escapes to the second race ring 12 side fixed to the swash plate 37 via the plurality of balls 13. .

  In the present embodiment, the plate thickness of the first track ring 11 is set larger than that of the second track ring 12. Further, a circumferential groove 21 having an arc-shaped cross section is formed on the contact surface 20 of the first track ring 11 with which the tip of the nose piston 35 contacts. The circumferential groove 21 is formed over the entire radial direction of the contact surface 20. In the present embodiment, the circumferential groove 21 is formed in the first raceway ring 11. However, the present invention is not limited to this, and the second raceway ring 12 is formed in the second raceway ring 12 by forming the circumferential groove 21 in the nose. You may arrange | position to the piston 35 side.

  In the present embodiment, the value of the radius of curvature R2 of the circular arc of the circumferential groove 21 and the radius of curvature R2 of the curved surface of the tip of the nose piston 35 are set to 1 or more and 10 or less. This setting is because, as shown in FIG. 3, the surface pressure tends to decrease when the value of R1 / R2 is 10 or less. Further, when the value of R1 / R2 approaches 1, the contact area increases. In FIG. 3, the surface pressure ratio is set to 1 as the surface pressure due to contact between the nose piston and a flat type (no circumferential groove 21) raceway ring. In general, the swing angle of the thrust ball bearing with respect to the nose piston does not exceed 15 °, and this is the same as in the present embodiment.

  As described above, according to the thrust ball bearing 10 of the present embodiment, the circumferential groove 21 having an arc-shaped cross section is formed on the contact surface 20 of the first race ring 11 with which the nose piston 35 comes into contact. The surface pressure between the first race ring 11 and the first race ring 11 can be suppressed, and the wear of the first race ring 11 can be reduced.

  Further, according to the thrust ball bearing 10 of the present embodiment, the value of the radius of curvature R2 of the circular arc of the circumferential groove 21 is set to 1 or more and 10 or less because the value of the radius of curvature R2 of the curved surface of the tip of the nose piston 35 is set. The surface pressure between the nose piston 35 and the first track ring 11 can be further suppressed, and the wear of the first track ring 11 can be further reduced.

  As a modification of the present embodiment, as shown in FIG. 4, the circumferential groove 21 may be formed in a part of the contact surface 20 of the first track ring 11 in the radial direction.

In addition, this invention is not limited to what was illustrated to the said embodiment, In the range which does not deviate from the summary of this invention, it can change suitably.
For example, in the above embodiment, the case where the present invention is applied to a single row thrust bearing is illustrated, but the present invention is not limited to this, and the present invention may be applied to a double row thrust bearing.
Moreover, although the case where this invention was applied to the thrust ball bearing was illustrated in the said embodiment, it is not limited to this, You may apply this invention to a thrust roller bearing.
Moreover, in the said embodiment, although the center of the circumferential groove 21 and the center of the nose piston 35 have matched, it is not limited to this, The front-end | tip part of the nose piston 35 should just contact the circular arc of the circumferential groove 21, and a circumferential groove The center of 21 and the center of the nose piston 35 do not have to be aligned.

10 Thrust ball bearing (thrust bearing)
DESCRIPTION OF SYMBOLS 11 1st track ring 11a 1st track surface 12 2nd track ring 12a 2nd track surface 13 Ball (rolling element)
14 Cage 20 Contact surface 21 Circumferential groove 30 Hydraulic continuously variable transmission 35 Nose piston R1 Radius of curvature of the circular arc of the circumferential groove R2 Curvature radius of curvature of the tip of the nose piston

Claims (2)

A first race ring having a first raceway surface;
A second race ring having a second raceway surface;
A plurality of rolling elements arranged to be freely rollable between the first raceway surface and the second raceway surface;
A cage for holding the plurality of rolling elements at substantially equal intervals in the circumferential direction,
In thrust bearings used in hydraulic continuously variable transmissions,
A thrust bearing, wherein a circumferential groove having a circular arc shape is formed on a contact surface of the first raceway ring or the second raceway ring that contacts a nose piston of the hydraulic continuously variable transmission. 2. The thrust bearing according to claim 1, wherein a value of a radius of curvature of an arc of the circumferential groove / a radius of curvature of a curved surface of a tip portion of the nose piston is set to 1 or more and 10 or less.

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