JPH07238880A - Planetary gear device - Google Patents

Abstract

PURPOSE:To prevent rotation of a bearing in relation to a planetary gear and also prevent the planetary gear from coming out axially. CONSTITUTION:In a planetary gear device used for an internal reduction type starter in which an oil impregnated metal powder sintered bearing 12 is press- fitted in the press fit hole 11a of a planetary gear, a plurality of grooves 22 extending to a middle way in an axial direction are provided in the inner periphery surface of the press fit hole 11a at intervals.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planetary gear device used in an internal reduction type starter.

[0002]

2. Description of the Related Art FIG. 5 is an axial sectional view showing a conventional internal reduction type starter disclosed in, for example, Japanese Patent Publication No. 63-44944, and FIG. 6 is a sectional view taken along line VI-VI in FIG. In the figure, 1 is a DC motor, 2 is a rotating shaft of the DC motor 1, and has a recess 3 formed at a front end portion and a spur gear 4 formed on an outer peripheral surface. Reference numeral 5 is an output rotary shaft having a recess 6 arranged to face the recess 3, 7 is a sphere engaged in the recesses 3 and 6, 8 is a cylindrical yoke of the DC motor 1, and 9 is The rear bracket 10 is a flange formed on the output rotary shaft 5, 11 is a planetary gear that meshes with the spur gear 4 and is driven by the rotary shaft 2, and the sintered oil-impregnated bearing 12 is press-fitted into the press-fitting hole 11a. ing. Reference numeral 13 is a support pin fitted to the flange 10, and supports the planetary gear 11 via a bearing 12. Reference numeral 14 denotes an internal gear to which the planetary gear 11 is internally meshed, and an intermediate bracket 16 is provided on the inner peripheral surface of the bracket 15.
It is installed with. Reference numeral 17 is an overrunning clutch, 18 is a shift lever engaged with a shift ring 19 of the overrunning clutch 17, 20 is a pinion, 2
1 is a front bracket.

The operation of the internal speed reduction type starter having the above-mentioned structure is well known in the art, and therefore its explanation is omitted.

[0004]

In the conventional planetary gear unit used for the internal reduction type starter, the bearing 12 at the time of press fitting is used.
Since the bearing 12 is deformed by the inclination of the
The contact area between the planetary gear 11 and the bearing 12 after press-fitting is made small, and the inner peripheral surface of the press-fitting hole 11a of the planetary gear 11 is subjected to finish processing after quenching in order to reduce deformation of the bearing 12 after press-fitting as much as possible. I am giving it. Therefore, press-fitting hole 11
The surface roughness of the inner peripheral surface of a is good, there is little biting of the bearing 12 after press fitting along the surface, the extraction pressure of the bearing 12 in the axial direction is small, and when a force is applied in the circumferential direction, It is said that 12 gradually shifts in the circumferential direction with respect to the planetary gear 11 (that is, rotates relative to each other), the outer peripheral surface is displaced, the tightening force decreases, and finally it comes off in the axial direction. There was a problem.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a planetary gear device capable of preventing the rotation of the bearing with respect to the planetary gear and preventing the axial gear from coming off.

Further, the present invention smoothes the rotation of the planetary gear by making the engagement between the planetary gear and the bearing uniform over the entire circumference.

[0007]

In the planetary gear device according to the present invention, a plurality of grooves are provided on the inner peripheral surface of the press-fitting hole of the planetary gear at intervals up to the middle of the axial direction. Also,
The grooves are formed at equal intervals over the entire circumference.

[0008]

In the present invention, when the bearing is press-fitted into the press-fitting hole of the planetary gear, the outer peripheral surface of the bearing swells and bites into the groove of the press-fitting hole. The engaging part and the groove mesh with each other and do not displace in the inner peripheral direction, or the groove is halfway, and the end face of this groove does not displace with respect to the axial force, preventing the bearing from rotating and coming off from the planetary gear. To be done.

Further, since the grooves are provided on the inner peripheral surface of the press-fitting hole at equal intervals over the entire circumference, engagement by the grooves can be uniformly obtained over the entire circumference.

[0010]

【Example】

Example 1. An embodiment of the present invention will be described with reference to FIGS. 1 is a cross-sectional view of a main part, FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1, FIG. 3 is a partial cross-sectional view in the axial direction of a planetary gear, and FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. The same or corresponding parts as those of the conventional device are designated by the same reference numerals and the description thereof will be omitted. In the figure, reference numeral 22 denotes a plurality of grooves provided on the inner peripheral surface of the press-fitting hole 11a of the planetary gear 11, which has a length up to the middle in the axial direction.

If a plurality of grooves 22 are provided on the inner peripheral surface of the press-fitting hole 11a of the planetary gear 11 as shown in FIGS. 3 and 4, when the bearing 12 is press-fitted into the press-fitting hole 11a, the structure shown in FIG. Figure 2
As shown in FIG. 6, the outer peripheral surface of the bearing 12 has a groove 22 of the press-fitting hole 11a.
Since it swells and bites inward, even if a force is applied in the circumferential direction, the biting portion 12a of the bearing 12 meshes with the groove 22 and is not displaced in the circumferential direction, or as shown in FIG. If so, the end surface 22a of the groove 22 and the biting portion 12a of the bearing 12 engage with each other as shown in FIG. Therefore, it is possible to prevent the bearing 12 from rotating with respect to the planetary gear 11 and prevent it from coming off.

Example 2. If the grooves 22 provided on the inner peripheral surface of the press-fitting hole 11a of the planetary gear 11 are formed at equal intervals over the entire inner peripheral surface as shown in FIG. 1, the outer peripheral surface of the bearing 12 is evenly distributed over the entire peripheral surface. Since the biting portion 12a is formed in the groove 22, the engagement between the biting portion 12a and the groove 22 becomes uniform over the entire circumference, and the planetary gear 11 rotates smoothly.

[0013]

As described above, according to the present invention, it is possible to prevent the rotation of the bearing with respect to the planetary gears and also prevent the axial slippage.

Further, according to the present invention, the effect that the rotation of the planetary gear becomes smooth can be obtained by making the engagement between the planetary gear and the bearing uniform over the entire circumference.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing a first embodiment of the present invention.

2 is a cross-sectional view taken along the line II-II in FIG.

FIG. 3 is a partial axial sectional view of a planetary gear.

4 is a cross-sectional view taken along the line IV-IV in FIG.

FIG. 5 is an axial sectional view showing a conventional device.

6 is a cross-sectional view of the main part taken along the line VI-VI of FIG.

[Explanation of Codes] 1 DC motor 2 Rotating shaft 5 Output rotating shaft 8 Cylindrical yoke 8a Cylindrical yoke collar 10 Flange 11 Planetary gear 11a Press-fit hole 12 Bearing 12a Bearing bit 13 Support pin 14 Internal gear 17 Overrunning clutch 18 Shift lever 20 Pinion 22 Groove 22a Groove end surface

Claims (2)

[Claims] 1. A planetary gear device used for an internal reduction type starter, wherein a sintered oil-impregnated bearing is press-fitted into a press-fitting hole of a planetary gear made of a sintered material. A planetary gear device characterized in that a plurality of grooves up to the middle of the axial direction are provided at intervals. 2. The planetary gear device according to claim 1, wherein the grooves are formed at equal intervals over the entire circumference.