JP2518093Y2 - Radial needle roller bearings for starters - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a radial needle roller bearing for a starter for starting an engine of an automobile.

[Conventional technology]

The starter used for starting the engine of an automobile is mainly an electromagnetic push type, and among them, a reduction type (with an internal reduction gear) is often used.

The reduction type starter is as shown in FIG.
The reduction gear 3 is provided between the drive shaft of the armature 1 and the pinion 2 of the output shaft, and the magnetic switch 4 is configured to engage and disengage the pinion 2 of the output shaft with respect to the ring gear 5. It is decelerated by the speed reducer 3 to increase the output of the pinion 2 to high torque.

In the cranking in which the output shaft is rotated to start the engine, the starter as described above has the maximum torque when the rotation is 0 as shown in the relationship diagram of cranking speed and cranking torque in FIG. Occurs, the torque decreases as the rotation increases, and therefore the rotation of the armature 1 becomes higher in order to obtain a high output.

Since the feature of such reduction type starter is high-speed rotation, the bearing used by being incorporated in the starter is required to have a function of excellent strength and grease life and low torque.

4 and 5 show a conventional radial needle roller bearing used in a reduction type starter,
FIG. 4 shows that the inner peripheral surface of the outer ring 6 is cut with a rolling groove 8 having a width in which the needle roller 7 fits, and a large number of needle rollers 7 arranged in the rolling groove 8 are located inside the outer ring 6. It is a solid needle roller bearing which is held at a constant interval by a cage 9.

Further, FIG. 5 shows that an outer ring 10 is formed by bending a metal plate into a U-shaped cross section, and a large number of needle rollers 12 are arranged in an inner circumferential rolling groove 11 of the outer ring 10. A shell-shaped needle roller bearing in which a cylindrical cage (13) housed in a rolling groove (11) holds it at regular intervals.

[Problems to be solved by the device]

By the way, in the conventional needle roller bearing as described above, the cage 9 and 13 have a small cross-sectional area and a large amount of movement in the axial direction and the radial direction.
It is difficult to support high-speed rotation, and the cage has a straight cross-sectional shape that has poor grease retention, and centrifugal force during high-speed rotation causes grease to flow out, which can shorten bearing life due to running out of grease. There is a problem.

Therefore, in order to solve the above problems, the present invention increases the cross-sectional area of the cage and reduces the amount of movement in the axial direction and the radial direction to improve the cage strength and grease retention. An object of the present invention is to provide a radial type needle roller bearing for a starter, which can have a long life.

[Means for solving the problem]

In order to solve the above problems, the present invention provides an outer ring having a rolling groove on its inner peripheral surface, a large number of needle rollers arranged in the rolling groove, and the needle rollers at constant intervals. Bending part consisting of a cage that holds the cage on both sides, and the cage is bent toward both sides into the rolling groove, and the radial direction by the rolling surface of the rolling groove and the axial direction by both side surfaces of the rolling groove are respectively guided. The outer ring guide type structure having a cross section is provided.

[Action]

Since the bends that extend outward in the radial direction are provided on both sides of the cage, the cross-sectional area is large, and the amount of movement in the axial and radial directions of the outer ring rolling groove is small. Therefore, the strength of the cage is excellent and the grease is retained reliably. It has a long life even at high speeds and loads.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. 1 of the accompanying drawings.

As shown in FIG. 1, a radial needle roller bearing 21 for a starter includes an outer ring 22, a large number of needle rollers 24 housed in rolling grooves 23 formed on the inner peripheral surface of the outer ring 22, A cage 25 that holds the needle rollers 24 at regular intervals in pockets, and the outer ring 22 is made of a metal plate and has a U-shaped cross section in which side walls 27 and 27 are bent on both sides of an annular wall 26. It is formed into a shape.

The retainer 25 is provided with bent portions 28, 28 that are bent outward in the radial direction on both sides of an annular portion having pockets, and has an outer ring.
It is formed in a substantially U-shaped cross-sectional shape that fits in the rolling groove 23 of 22.

The cage 25 which is housed in the rolling groove 23 of the outer ring 22 is guided by the bent portions 28, 28 on both sides in the radial direction by the rolling surface of the rolling groove 23 and the axial direction by the side surfaces of the side walls 27, 27, respectively. The amount of movement in the axial and radial directions is small.

As described above, when the cage 25 has a substantially U-shaped cross-section, the cross-sectional area becomes large and the amount of movement in the axial direction and the radial direction is small, so that the strength of the cage 25 is improved.

In addition, the cage 25 has a substantially U shape in which bent portions 28, 28 are provided on both sides.
With the V-shaped cross-sectional shape, the grease retaining property in the rolling groove 23 is improved, which is advantageous in terms of grease life.

The retainer 25 is not limited to the substantially U-shaped cross-sectional shape shown in FIG. 1, but may have a similar U-shaped cross-section with bent portions provided on both sides of a straight annular portion.

Further, in order to reduce the contact friction between the cage 25 and the needle roller 24, the entire surface of the cage 25 may be coated with ethylene tetrafluoride resin. For example, in the case of grease lubrication, the contact friction is 20%. It can be lowered, and it can meet the demand for low torque as a bearing for a high-speed starter.

〔effect〕

As described above, according to the present invention, the cage to be housed in the rolling groove of the outer ring is the outer ring guide type having the cross-sectional shape in which the bent portions that bend outward in the radial direction are provided on both sides. The cross-sectional area of the cross-sectional shape can be increased, and the bending portion reduces the amount of movement of the cage in the axial direction and the radial direction, so that the cage strength can be improved.

In addition, since the cage is provided with bent portions on both sides, the grease can be held well, which is advantageous in extending the life of the grease.

Therefore, it is possible to exhibit sufficient durability as a radial needle roller bearing for a starter, which is capable of high-speed rotation and high load.

[Brief description of drawings]

FIG. 1 is a sectional view of a needle roller bearing according to the present invention, FIG. 2 is a sectional view showing a schematic structure of a reduction type starter, FIG. 3 is a relationship diagram of cranking speed and cranking torque, and FIG. And FIG. 5 are sectional views showing a conventional needle roller bearing. 21 …… Needle roller bearing, 22 …… Outer ring, 23 …… Rolling groove, 24…
… Needle rollers, 25 …… Cages, 27 …… Sidewalls, 28 …… Bends.

Claims (1)

(57) [Scope of utility model registration request] 1. An outer ring having a rolling groove formed on its inner peripheral surface, a large number of needle rollers arranged in the rolling groove, and a cage for holding the needle rollers at regular intervals. An outer ring guide with a cross-sectional shape in which the cage is bent on both sides toward the inside of the rolling groove, and bent portions are provided to guide the radial direction by the rolling surface of the rolling groove and the axial direction by both sides of the rolling groove. Radial needle roller bearings for starters.