GB2113319A

GB2113319A - Bearing with improved stability

Info

Publication number: GB2113319A
Application number: GB08236011A
Authority: GB
Inventors: Toshinori Tanaka; Akira Morishita
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 1981-12-22
Filing date: 1982-12-17
Publication date: 1983-08-03
Also published as: GB2159893A; GB2113319B; FR2518654B1; GB8517946D0; GB2159893B; FR2518654A1; JPS5896123U

Abstract

A bearing for an engine starter motor is fitted to a thermoplastic resin frame 24 and is held in position by projections 27 on the frame 24 engaging the end face of the bearing 26. Radial projections and recesses on the outer surface of the bearing and inner surface of the frame also interengage. <IMAGE>

Description

SPECIFICATION Bearing with improved stability The present invention relates to a bearing means, for example, in a starter motor for an engine.

Motors of the type shown in Fig. 1 for starting engines are well known in the prior art. In Fig. 1, 1 is a D.C. motor. There is a front bracket 6 fixed at the forward end of a cylindrical yoke 2 of this motor 1. An internal gear 3 of a deceleration mechanism 7, an intermediate bracket 4 and a rubber ring 5 are fitted at the inner peripheral surface of this bracket 6. A rotary shaft 9 is fitted in an armature 8 of the D.C. motor 1. A spur gear 10 is engaged with a planetary gear 11. The planetary gear 11 is rotatably supported on a support pin 1 3 via a bearing 1 2 and is also engaged with the internal gear 3.The above mentioned support pin 1 3 is fixed to a flange 14, which is integrally formed with an output rotary shaft 1 5. A sleeve bearing 1 6 is fitted at the inner peripheral surface of the intermediate bracket 4, and the sleeve bearing 1 6 supports the output rotary shaft 1 5.

A sleeve bearing 1 7 is fitted in a recess 1 8 which is formed in the inner peripheral surface at the rearward end of the output rotary shaft 1 5. The sleeve bearing 1 7 supports the forward end of the rotary shaft 9 of the armature. A steel ball 1 9 is interposed between the forward end of the rotary shaft 9 of the armature and the rearward end of the output rotary shaft 1 5 which is arranged on the extension of the axis of this rotary shaft 9.

The function of the steel ball is to impart and absorb the thrust loading of both rotary shafts 9, and 15. In Fig. 1, 20, 21 and 22 are thrust washers, and 23 is a helical spline which is formed on the outer peripheral surface of the output rotary shaft 1 5 and to which an overrun clutch (not shown) is splinecoupled.

The operation of the above-described motor will now be described. An electric current energizes the armature 8 thereby resulting in rotation of rotary shaft 9. This rotational power is transmitted from the rotary shaft 9 of the armature to the flange 1 4 via the spur gear 10, the planetary gear 11 and the support pin 13, so that the rotational speed of the armature 8 is decelerated by the planetary gear mechanism 7 and transmitted to the output rotary shaft 1 5.

If the intermediate bracket 4 is made of synthetic resin material, in order to lower the cost and reduce the weight of the motor, then a problem results in that the sleeve bearing 1 6 which is fitted to the intermediate bracket 4 becomes mispositioned due to stress.

The object of the invention is to provide a bearing device for a starter motor which has the advantages of the use of synthetic resin materials, in cost and light weight but which has strength sufficient to support the bearing.

According to the present invention there is provided a bearing device comprising a frame made of thermoplastic resin material and having at least one engaging portion on its inner peripheral surface; and a bearing element fitted to said frame and having à least one end in engagement with said engaging portion.

A sleeve bearing may be fitted to the frame, which may be an intermediate bracket made of a thermoplastic synthetic resin material.

Said at least one engaging portion may be formed with a projection by deformation when the frame is heated at its inner peripheral surface. At least one end surface of the bearing is adapted to come into engagement with the engaging portion so as to absorb the thrust loading of the bearing. this maintains the bearing in proper position, solving the above mentioned problem while stabilizing the mounting strength of the bearing over the long term.

The invention will now be described by way of example with reference to and as shown in the accomanying drawings in which: Figure 1 is an upper half side view in cross section showing the forward portion of an engine starter motor which is provided with conventional bearing means.

Figure 2 is an upper half side view in cross section showing a bearing means constructed in accordance with a first embodiment of the present invention; Figure 3 is a cross sectional view taken along Ill-Ill line in Fig. 2; and Figure 4 is a perspective view showing one end portion of a sleeve bearing constructed in accordance with a second embodiment of the present invention.

In the drawings, the same reference numerals denote the same elements.

A first embodiment of the present invention will be explained with reference to Fig. 2 and Fig. 3, and a second embodiment will be explained with reference to Fig. 4. In Fig. 2 and Fig. 3, 24 is an intermediate bracket which is manufactured in accordance with well known mold processing methods with nylon as the material for the main component.

A sleeve bearing 26 is fitted at the inner peripheral surface 25 of bracket 24. Both the ends of the bracket 24 are caulked in accordance with well known thermal caulking processing methods and engaging portions 27, 27 project from the inner peripheral surface 25, to engage both end surfaces of the sleeve bearing 26. In addition, a plurality of grooves 28 are formed circumferentially in the outer peripheral surface of the sleeve bearing 26.

Projections 29 which are provided on the inner peripheral surface of the intermediate bracket 24 engage the grooves 28 so as to provide a mechanism to prevent relative rota tion between the sleeve bearing 26 and the intermediate bracket 24.

The above-mentioned intermediate bracket 24 and sleeve bearing 26 are assembled into the starter motor in such a way that the intermediate bracket 4 and the sleeve bearing 1 6 which are shown in Fig. 1 are respectively replaced. Because all of the parts in this embodiment, other than the intermediate bracket and the sleeve bearing, are the same as those in Fig. 1, they are not shown and the explanation of their operation has been omitted.

A starter motor with the bearing means as described above, is able, over the long term, to absorb the loading in both the axial thrust direction and the radial direction, which are applied to the sleeve bearing 26. This is achieved by the engagement of the grooves 28 of the sleeve bearing 26 and the projections 29 of the intermediate bracket 24 and by employing a simple means to make the engaging portions 27, 27 project from the inner peripheral surface of the intermediate bracket 24 when heated.

A second embodiment allows the intermediate bracket to absorb the radial loading of the sleeve bearing with the end surface of the sleeve bearing by forming radially projected and recessed engaging portions 31 at one or both the end surfaces of the sleeve bearing 30, as shown in Fig. 4. The sleeve bearing 30 is mounted to the intermediate bracket 24, as shown in Fig. 2, and the projecting and recessed engaging portions 31 at the ends of the sleeve bearing 30 are fitted to the engaging portions 27, which are formed on the intermediate bracket 24 in accordance with the thermal caulking method. In this case, there is no necessity to provide the projections or recesses on the outer peripheral surface of the sleeve bearing, and the sleeve bearing may therefore be cylindrical. This is advantageous in that the intermediate bracket will be easy to manufacture.

Although the embodiments have been explained with respect to the case in which the sleeve bearing is mounted to an intermediate bracket in a starter motor, the bearing in this invention may be another type of bearing, for example, a ball bearing. In addition, the present invention is widely applicable in cases where the bearing is mounted to a general frame in other instruments or devices.

The bearing means constructed in accordance with the present invention as explained hereinabove, there are provided engaging portions which project, by deformation during a heating step in the fabrication process, at one location or a plurality of locations on the inner peripheral surface of a frame which is made of a thermoplastic synthetic resin material such as nylon. At least one end of the bearing is in engagement with the engaging portion so as to receive the axial thrust loading of the bearing. It therefore becomes possible to prevent the axial displacement of the bearing, over the long term, despite the fact that the frame is light and simply constructed. A further advantage of the present invention is that it is possible to provide the bearing means with a high reliability at a low cost.

Claims

1. A bearing device comprising a frame made of thermoplastic resin material and having at least one engaging porttion on its inner peripheral surface; and a bearing element fitted to said frame and having at least one end in engagement with said engaging portion.

2. A bearing device as claimed in Claim 1, wherein said at least one engaging portion is formed by heat deformation during fabrication of said frame.

3. A bearing device as claimed in Claim 1 or claim 2 wherein said bearing element includes at least one surface irregularity on said at least one end for engaging said engaging portion.

4. A bearing device as claimed in claim 3, wherein said surface irregularity is an axial projection.

5. A bearing device as claimed in Claim 3, wherein said surface irregularity is a recess in said at least one end.

6. A bearing device as claimed in Claim 1, wherein said frame includes at least one radial surface irregularity.

7. A bearing device substantially as hereinbefore described with reference to and as shown in Figs. 2 and 3 of the accompanying drawings.

8. A bearing device substantially as hereinbefore described with reference to and as shown in Fig. 4 of the accompanying drawings.