JPS608571A - Casing - Google Patents

Abstract

PURPOSE:To enable the mounting to a mounting part to be improved, by forming a plurality of supporting protrusions in the specific range of a circular internal peripheral surface of the mounting part in a casing and gradually decreasing the height of said protrusion in its diametric direction as its distance increases from the center of said specific range. CONSTITUTION:A casing molded by die casting from a light metal material forms on the internal surface of a side wall 2 a mounting part 6 having a circular internal peripheral surface 4, further the circular internal peripheral surface 4 forms a plurality of supporting protrusions 20' at an equal interval in the peripheral direction. Here each supporting protrusion 20' is provided not over the full circumference of the circular internal peripheral surface 4 of the mounting part 6 but locally in a part of the circular internal peripheral surface 4 within a range at an angle of about 180 deg. or less. Then the protrusive height of each supporting protrusion 20' is gradually decreased as its distance increases from the center of said angular range. In this way, a bearing member can be mounted in a good condition because its circular peripheral surface is brought in direct contact with the circular internal peripheral surface 4 of the mounting part 6 in the direction of an arrow head 22.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a casing, and more particularly to a casing formed from a light metal material by die casting.

For example, in various devices such as automatic door devices, a variable speed gear mechanism is used as a mechanism to change the rotational output of an appropriate drive source such as an electric motor to an appropriate speed and transmit it to a driven part. . This speed change gear mechanism generally includes a plurality of various gears and a gear box serving as a casing that rotatably supports a shaft to which these gears are fixed and that surrounds the gears. The shaft is supported on the gear box by forming a mounting portion having a circular inner circumferential surface on the inner wall of the gear box, and mounting a bearing member having a circular outer circumferential surface on the shaft; This is accomplished by attaching the above to the attachment section.

Recently, it has been proposed and put into practical use that a casing such as the gear box is formed from a light metal material such as aluminum or an aluminum-based alloy by die casting. However, in the die-cast condition, it is not possible to properly mount the bearing member to the mount part in the required throughput due to the existence of a draft on the circular inner circumferential surface of the mount part. ,
Therefore, conventionally, it has been necessary to perform precision machining on the circular inner peripheral surface of the mounting portion after die-casting, and the manufacturing cost of the casing has become considerably high due to such precision machining. Ta.

On the other hand, as a structure that can be used directly in the die-cast state without precision machining,
No. 80653 discloses that an opening that matches the circular inner peripheral surface of the mounting part is formed in the wall where the mounting part is formed, and the so-called draft angle between the opening and the circular inner peripheral surface of the mounting part is made from the outer wall surface. It is disclosed that the inner diameter is gradually reduced toward the tip of the mounting part, and furthermore, radial through grooves are formed at intervals in the circumferential direction in the cylindrical wall of the mounting part. In the structure disclosed in Japanese Utility Model Application Publication No. 50-806533, the bearing member is press-fitted into the mounting part from the outer wall side, and at this time, due to the presence of the groove, the cylindrical shape of the mounting part is The wall elastically deflects radially outwardly, thus elastically retaining the bearing member in the mounting portion. However, the above structure disclosed in Japanese Utility Model Application Publication No. 50-80653 is not fully satisfactory; (a) there is an axial draft on the circular inner circumferential surface of the mounting part that supports the bearing part; Therefore, the outer circumferential surface of the bearing member is not brought into contact with the circular inner circumferential surface of the mounting part over the entire width in the axial direction, and the supporting action of the bearing member by the mounting part works only in a very small part in the axial direction. , Therefore, the bearing member is not held sufficiently, and vibration of the bearing member and noise caused by this are observed. , Also from this point of view, it is not possible to make the holding strength of the bearing system sufficient. (2) It is necessary to provide the die-casting mold with a plurality of relatively thin flap pieces to define the grooves, but such flap pieces are short-lived. There are problems and drawbacks, such as a high risk of damage over time.

The present invention has been made in view of the above facts, and its main purpose is to provide a casing formed from a light metal side obliquely by die-casting, without performing precision machining on the mounting portion after die-casting. Die cast! ! In this state, the bearing member can be press-fitted into the mounting portion without causing any problems, and in particular, a relatively large force in a predetermined angular direction is applied to the shaft.
Therefore, even if a relatively large force is applied locally to a predetermined angular position on the circular inner circumferential surface of the mounting part, the press-fitted bearing part side can be held or supported sufficiently reliably and firmly.
Our objective is to provide a new and superior casing.

According to the present invention, as a casing that achieves the above object, the casing is formed from a light metal side obliquely by die casting, the inner wall surface of the casing is formed with a mounting portion having a circular inner circumferential surface, and a shaft is formed. In a casing in which a bearing part having a circular outer circumferential surface for rotatably supporting the bearing part is press-fitted into the mounting part; an angular range of approximately 180 degrees or less of the circular inner circumferential surface of the mounting part A plurality of support protrusions extending in the axial direction are formed at intervals in the circumferential direction, and the protrusion height in the radial direction of the support protrusions is gradually decreased as the distance from the center of the angular range increases. A casing is provided that is characterized by:

A more detailed explanation will be given below with reference to the accompanying drawings.

Referring to FIGS. 1 and 2, a casing formed by die-casting from a suitable light metal material such as aluminum or an aluminum-based alloy has a mounting part on the inner surface of its side wall 2 that is similar to the mounting part in a conventional casing. Similarly, a mounting portion 6 having a circular inner circumferential surface 4 is formed.

A plurality of (eight in the illustrated case) support protrusions 20 are formed on the circular inner circumferential surface 4 of the mounting portion 6 at equal intervals in the circumferential direction. The radial protrusion heights of these support protrusions 20 are substantially the same.

When molding the casing by die-casting, in order to perform die-cutting, each of the plurality of support protrusions 20 formed therein as well as the circular inner circumferential surface of the mounting portion 6 is also die-cut. It is necessary to generate a gradient, but
It is desirable that the draft angle in each of the plurality of support protrusions 20 is generated on the circumferential surface of the support protrusion 200, and not on the radial inner surface of the support protrusion 20. That is, in each of the support protrusions 20, the circumferential width of the support protrusion is equal to the mounting portion 6.
A draft angle is generated on the circumferential surface of the support protrusion 200 so that it gradually increases from the receiving end (protruding end) to the bottom end (base end) of the supporting protrusion 20. There is virtually no draft on the inner surface, so the support projection 2
The diameter D5 of the circle defined by the radial inner surface of each of 0
It is desirable that the curves are uniform without fluctuation in the axial direction.

In the mounting portion 6 as described above, the inner diameter D1 of the circular inner circumferential surface 4 is equal to the inner diameter D1 of the circular outer circumferential surface 1 of the bearing member 14 to be mounted thereon.
The outer diameter D2 of 2 is also set slightly larger, on the other hand,
The diameter D5 of the circle defined by the radial inner surfaces of the plurality of support protrusions 20 is also set slightly smaller than the outer diameter D2 of the circular outer peripheral surface 12 of the bearing member 14. The radial protrusion height of the plurality of support protrusions 20 depends on the inner diameter 1 of the circular inner circumferential surface 4, the outer diameter D2 of the circular outer circumferential surface 12, and the side slope used in die casting of the casing. ,Typically,
It is about ηoo to 10/1oo ttm (in order to clearly illustrate the support protrusion 20, the radial protrusion height of the support protrusion 20 is exaggerated in the drawing).
.

In the case of the above-mentioned 9th casing, die-casting 1tt
A shaft J with a gear (not shown) fixed in its mounting part 6 without any machining after Q construction.
A bearing member 14 for rotatably supporting O is attached by press fitting such as press fitting. In this way, due to the press-fitting of the bearing member 14, the plurality of support protrusions 20 are forcibly deformed so that the diameter D5 is made equal to the outer diameter D2 of the outer circumferential surface of the bearing member 14, and thus the bearing member 14
is mounted in the mounting section 6.

Therefore, the casing equipped with the above-mentioned through-hole mounting part 6 is as follows:
Although this is fully satisfactory under normal usage conditions, when a relatively large force acts on the shaft 10 in a predetermined angular direction,
Therefore, when a large force is locally applied to a predetermined angular position on the circular inner circumferential surface of the mounting portion, the following problems tend to occur. P [J, gear housed in the casing (
(not shown) are engaged with other gears (not shown) which are also housed within the casing. When two gears are to be engaged with each other, as is well known to those skilled in the art, each gear, and therefore the shaft to which each gear is fixed, and the bearing member that pivotally supports such shaft, each have two gears. A force acts in the direction of mutual separation, that is, in the eccentric direction. Therefore, in the mounting portion 6 into which the bearing member 14 is press-fitted, force is applied from the bearing member 14 to the mounting portion 6 concentrated in a specific angular direction (for example, the direction indicated by the arrow 22 in FIG. 5). Become. Therefore, if the force concentrated in the specific angular direction and acting on the mounting part 6 is quite large, and if there is a support protrusion in and near the specific angular direction, a large force will act on the support protrusion, This further deforms the support protrusion, causing looseness in the mounting of the bearing part, and in some cases, there is a risk that the support protrusion may be damaged.

According to the present invention, the following improvements are made in order to solve such problems. Referring to FIG. 3, which shows an example of a casing constructed in accordance with the present invention, according to the present invention, the plurality of support protrusions 20' are
It is disposed not over the entire circumference of the circular inner circumferential surface 4 of the mounting portion 6, but locally in a portion of the circular inner circumferential surface 4 within an angular range of approximately 180 degrees or less. The protrusion height of the plurality of support protrusions 20 is gradually reduced as the distance from the center of the angular range increases.

In such a casing constructed according to the present invention, in an angular range of at least approximately 180 degrees around the direction indicated by arrow 22 corresponding to the eccentric direction of the gear,
No support protrusions are provided on the circular inner circumferential surface 4 of the mounting portion 6, and the plurality of support protrusions 20' are formed at an angle of approximately 180 degrees or less centered on the direction opposite to the direction indicated by the arrow 22. The mounting portion 60 is locally disposed on the circular inner circumferential surface 4 in the range. In such a second specific example, there is no support protrusion in the direction indicated by the arrow 22 and in the vicinity thereof, and the circular outer circumferential surface of the bearing member is in contact with the circular inner circumferential surface 4 of the mounting portion 6 in such a portion. The above-mentioned force, which comes into direct contact and acts concentratedly in the direction indicated by the arrow 22, is directly transmitted to the circular inner circumferential surface 4 of the mounting portion 6 itself, which has considerably greater strength than the support protrusion.

Therefore, even if the force acting concentratedly in the direction of the arrow 22 is considerably large, there will be no looseness in the mounting of the bearing member or damage to the mounting portion.

[Brief explanation of drawings]

FIG. 1 is a partial front view showing a mounting portion of a casing in which support protrusions are arranged at intervals over the entire circumference of a circular inner circumferential surface of the mounting portion. FIG. 2 is a partial sectional view of the mounting portion shown in FIG. 1. FIG. 3 is a partial front view showing the mounting portion of the casing constructed according to the present invention. 2...Side wall of the casing 4...Circular inner circumferential surface of the mounting portion 6...Mounting portion 14...Bearing members 20 and 22...Support protrusion Patent applicant Akira Kawabata, Sunny Corporation Agent Patent attorney Nao Jun Ono

Claims (1)

[Claims] 1. A casing formed from a light metal side obliquely by a die-casting method, the inner wall surface of which is formed with a mounting portion having a circular inner circumferential surface, the shaft of which can be freely rotated. In a casing into which a bearing member having a circular outer circumferential surface for supporting is press-fitted into the mounting part; A plurality of support protrusions extending in the axial direction are formed at intervals in the angular range, and the radial protrusion height of the support protrusions is gradually reduced as the distance from the center of the angular range increases. Characteristic casing.