JPS608210Y2 - Transmission case structure - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the structure of an aluminum die-cast transmission case including a fitting portion for a bearing.

[Prior art]

Conventionally, the structure of this type of transmission case was
Japanese Patent No. 65137 discloses a structure in which a circumferential groove is provided on the inner surface of a bearing case into which an outer ring of a bearing fits, and an oil-impregnated metal member is inserted into this groove.

In this known technology, under normal load conditions, the outer ring of the bearing does not idle due to its engagement with the inner surface of the bearing case, but when the load becomes large and heat is generated, oil seeps out from the oil-impregnated metal member, and this oil film causes the outer ring to idle. Although it is effective in preventing wear between the outer ring and the inner surface of the bearing case, it only allows the outer ring to idle inside the bearing case, and even with lubrication, the contact between the outer ring and the inner surface of the bearing case is There is a drawback that friction inevitably occurs between the two, and wear cannot be completely prevented.

The above drawbacks are caused by the bearing outer ring idling inside the bearing case, so it is necessary to completely prevent this idling.To do this, it is necessary to increase the rigidity of the bearing case and improve the machining accuracy of the inner surface of the case. Conventional methods have been taken to increase the strength of the fit between the outer ring of the bearing and the inner surface of the case to the extent that the outer ring does not spin idly, but this method has the drawback of increasing man-hours during production and increasing costs. .

[Problem to be solved by the invention 3 The technical problem to be solved by the invention is to reduce the pressure contact area between the outer ring of the bearing and the inner surface of the bearing case while maintaining sufficient pressure contact strength to prevent the outer ring of the bearing from idling. The aim is to provide a transmission case structure that is durable and easy to process.

[Means to solve the problem]

The technical measure taken to solve the above problem is to have an inner circumferential surface with a smaller diameter than the outer diameter of the bearing on the inner circumferential part of the fitting part for the bearing, which exceeds the semi-circumference in the circumferential direction of the bearing. The protrusions are integrally formed so as to be juxtaposed in the axial direction of the bearing, and a cylindrical surface that tightly fits with the outer circumferential surface of the bearing is formed on the remaining inner circumferential portion in the circumferential direction of the bearing.

[Effect]

The above technical means works as follows.

Of the bearing fitting part, a protrusion is integrally formed on the inner circumferential part of the range exceeding half the circumference of the bearing in the direction of the bearing axis, and the inner surface of the tip has a diameter smaller than the outer diameter of the bearing. Since it forms a cylindrical surface that tightly fits with the outer circumferential surface, the pressure contact area between the bearing outer ring and the inner surface of the bearing case is reduced by the area of the annular groove between each protrusion, and the fitting part of the bearing case is When fitting a bearing, the tip of the protrusion, which has a diameter smaller than the outer diameter of the bearing, is pressed and deformed along the circumferential surface of the outer ring of the bearing, working together with the remaining cylindrical surface that fits tightly to align the circumferential surface of the outer ring of the bearing. It can be pressed very strongly.

[Effect of idea]

The present invention achieves the effects of the above-mentioned method.

As mentioned above, the tip of the protrusion is pressed and deformed, working together with the remaining closely-fitting cylindrical surface to uniformly and strongly press the outer peripheral surface of the bearing, so there is sufficient pressure contact strength to prevent the outer ring of the bearing from idling. Therefore, since there is no friction caused by idling, the structure of the transmission case can be made highly durable.

Furthermore, the tip diameter of the protruding portion need only be made smaller than the outer diameter of the bearing, and precision is not so strictly required, making processing of the transmission case easier. Since the position of the axial center of the bearing with respect to the core is uniquely determined by the closely fitted cylindrical surface, a unique effect has been achieved in that the positional accuracy of the bearing with respect to the case is ensured.

〔Example〕

Next, embodiments of the present invention will be described based on the drawings.

In a transmission case installed in an agricultural machine such as a combine harvester, in order to allow the case 1 to rotatably support the input shaft 2, both 1,
A bearing 3 is interposed between the case 1 and the input shaft 2, with the bearing 3 being fitted internally into the case 1 and externally fitted onto the input shaft 2.

The transmission case 1 is manufactured by die-casting aluminum, and protrusions 4 are arranged in the bearing axial direction in a portion of the bearing fitting portion that exceeds at least a half circumference in the bearing circumferential direction. and are integrally connected with each other so that the diameter of the tip is smaller than the outer diameter of the bearing, and furthermore, the ring is tightly fitted with the outer circumferential surface of the bearing 3 in the remaining portion of the circumferential direction of the bearing that exceeds at least a semi-circumference. A cylindrical surface 5 is formed, and when the bearing 3 is assembled, it is pressed into the case bearing fitting part and the tip of the protrusion is pressed and deformed to be positioned at a predetermined position.

That is, in the bearing assembled state, the outer periphery of the bearing is brought into pressure contact with the protrusion 4 and the part of the case without the protrusion 4, and the axis of the bearing 3 is uniquely aligned with the axis of the case, This is to ensure that the assembly is done in a predetermined position without any looseness at a predetermined location.

The case 1 is divided by a dividing line that divides the bearing fitting part, and by making it easier to press the bearing 3 into the case fitting part, it is easier to assemble the case as a whole. This is the aim.

[Brief explanation of drawings]

The drawings show an example of the structure of the transmission case according to the present invention,
FIG. 1 is a side view of the main parts, and FIG. 2 is a cross-sectional view taken along the line nn in FIG. 1. 1...Case, 3...Bearing, 4
...Protrusion, 5...Cylindrical surface.

Claims (1)

[Scope of Claim for Utility Model Registration] ■ In the aluminum die-cast transmission case 1 equipped with a fitting portion for the bearing 3, the fitting portion for the bearing 3 within a range exceeding a semi-circumference in the circumferential direction of the bearing 3. Projections 4 having an inner circumferential surface smaller in diameter than the outer diameter of the bearing are integrally formed on the circumferential portion of the bearing 3 in parallel to each other in the axial direction of the bearing, and the bearing 3 is formed on the remaining inner circumferential portion of the bearing 3 in the circumferential direction. The structure of the transmission case is formed by forming a cylindrical surface 5 that tightly fits with the outer peripheral surface. (2) The structure according to claim (2), wherein the transmission case 1 is divided by a dividing line that divides the bearing fitting portion.