JP2510763Y2 - Bush press fitting structure with brim - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial field of application) The present invention relates to a press-fitting structure of a bush with a brim, which is arranged in a belt drive system and is applied to, for example, a fixed portion of an idle vehicle.

(Prior Art) For example, in an automobile engine, a fixed idler is set in a belt system that drives a camshaft, an oil pump, a water pump and the like by a timing belt. When mounting this fixed idler on an engine front case made of aluminum, etc., a steel washer or bush with flange is usually interposed between the fixed idler and the engine front case in order to secure the strength of the mounting surface. .

Of these, the washer has a simple ring shape, so it is easy to secure the levelness between the idler and the engine front case, but the washer may be missing during assembly or the washer may be forgotten to be attached. is there.

Therefore, recently, instead of this washer, it has become common to press-fit a bush with a brim into a bush press-fitting hole formed in an idler mounting portion such as an engine front case before shipment.

FIG. 4 shows a state in which the bush 1'with a brim is press-fitted into the mating member 2'according to the prior art.

As is apparent from this figure, conventionally, the bush with bush 1'has a long press-fitting shaft length, and the entire surface of the bush 1'is in contact with the inner surface of the press-fitting hole of the mating member 2 '. 1 press-fitting shaft 1'b and brim surface 1'c,
The squareness of 1'd, the parallelism of both sides 1'c and 1'd of the collar portion 1'a, and the squareness of the press-fitting hole inner surface 2'b of the mating member 2'and its bush seat surface 2'a, It is necessary to ensure the accuracy of parallelism between the bush seat surface 2'a of the mating member 2'and its mounting surface 2'c.

If all of these accuracies are not sufficiently ensured, for example, the parallelism between the idler mounting surface 1'c and the engine front case mounting surface 2'c cannot be ensured, and the idler is mounted at an inclined position and the timing is improved. This is because there is a risk that the belt will squeeze out of the idler and damage the belt.

(Problems to be solved by the invention) Therefore, according to the conventional press-fitting structure of the bush with a brim,
It is necessary to secure processing accuracy such as parallelism between the upper and lower surfaces of the brim, perpendicularity between the upper and lower surfaces of the brim and the press-fitting shaft, parallelism between the mounting surface of the mating member and the bush seat surface, and perpendicularity between these surfaces and the press-fitting hole. Despite this, it is difficult to secure it, and if this is not secured, it will inevitably lead to an increase in processing cost and also affect work efficiency. Further, the conventional bush with brim has a problem that the press-fitting length of the press-fitting shaft is long and therefore a large force is required for press-fitting the bush.

Therefore, in the present invention, when the bush with a collar is used as described above, the squareness of the press-fitting shaft of the bush with the collar and the flange surface and the squareness of the inner surface of the press-fit hole of the first member and the flange surface of the first member are machined. It was devised to ensure the levelness between the first and second members without being affected by accuracy.

[Constitution of device]

(Means for Solving the Problems) For this reason, the present invention is a brim and a column which are fixed in a state of being interposed between the first member and the second member, and whose upper surface serves as a seating surface for mounting the second member. And a bush with a flange formed of a material having a higher strength than that of the first member. The press-fitting shaft of the bush with the flange is press-fitted into a cylindrical press-fitting hole of the first member. In the structure, only the outer peripheral surface of the tip portion of the press-fitting shaft or the inner peripheral surface of the press-fitting hole facing the tip end portion of the press-fitting shaft is provided with a narrow projection on the surface facing the press-fitting shaft, and the press-fitting shaft and the A gap is formed between the brim and the projecting portion between the press-fitting hole and this is a means for solving the problem.

(Operation) When the bush with flange is press-fitted into the mating member, the projection end of a protrusion formed, for example, in an annular shape, provided on the outer peripheral surface of the press-fit shaft of the bush with flange or the inner peripheral surface of the press-fit hole of the mating member in the axial direction. Is pressed against the press-fitting surface of the other party and both are fixedly integrated.

The cross-sectional shape of the protruding end of the protruding portion may be a pin angle, an arc having a desired curvature, or a flat surface, but the axial length of the protruding end is set to be as small as possible in order to minimize contact with the counterpart.

As a result, it is possible to eliminate the influence of processing accuracy on the squareness of the bush with brim and the mating member and the press-fitting section, and it is possible to perform accurate assembly simply by ensuring the accuracy of the parallel surface between each assembly member. To do.

(Embodiment) Hereinafter, the present invention will be described more specifically based on the illustrated embodiment.

FIG. 1 shows an example of an idler assembling structure to which the present invention is applied. After the bush 1 with a collar is press-fitted into the press-fitting hole of the mating member (first member) 2, the idler (second member) 3 is attached to the bush 1. The bolt 4 is placed on the brim portion 1a, and the bolt 4 is tightened to the mating member 2 via the idler 3 and the bush with brim 1 to complete the assembly.

The press-fitting structure of the bush with flange shown in FIG. 1 is an example in which an annular protrusion is formed on the side of the bush with flange, and the press-fitting state is shown enlarged in FIG.

In FIG. 2, 1 is a bush with a brim, and 2 is a mating member into which the bush 1 is press-fitted. In this illustrated example, the outer diameter of the press-fitting shaft 1b of the bush 1 with a flange is set smaller than the inner surface diameter of the press-fitting hole of the mating member 2, and the tip of the press-fitting shaft 1b has an annular shape of approximately the same diameter as the press-fitting hole of the mating member 2. The protrusion 1e is formed. On the other hand, the inner surface 2b of the press-fitting hole of the mating member 2 is a straight cylindrical surface.

With such a configuration, the bush with brim 1 and the mating member 2
When press-fitting into, the contact (press-fitting) area of both members at the press-fitting part is small, so press-fitting is possible with a small force, and only the tip protrusion 1e of the press-fitting shaft 1b is press-fitting into the press-fitting hole of the mating member 2. , The lower surface 1d of the collar portion 1a and the mating member 2
The surfaces of the bush seating surfaces 2a of the above are easily adapted to each other, and the surfaces can be brought into close contact with each other without being affected by the squareness accuracy of the press-fitting shaft of the bush 1 and the press-fitting hole of the mating member 2. Therefore, for example, whether or not the idler 3 can be assembled in parallel with the mating member mounting surface depends on whether each of the upper and lower surfaces 1c and 1d of the brim portion of the bush 1 with brim, the bush seat surface 2a of the mating member 2, and the mating member mounting surface 2c. It only depends on the parallelism accuracy between the surfaces, and is not affected by the squareness accuracy of the press-fitting shaft 1b and the press-fitting hole 2b.

Fig. 3 shows an example in which the flanged bush 1 has not been subjected to any special processing, and an annular step 2d has been formed in the press-fitting hole 2b of the mating member 2, in the vicinity of the bottom of the press-fitting hole. The inner diameter of the press-fit shaft 1b to approximately match the outer diameter of the press-fit shaft 1b
An annular step portion (protruding portion) 2d is formed in the press-fitting hole 2b by setting the diameter larger than the outer diameter of 1b.

In this embodiment as well, as in the above example, the accuracy of squareness processing is not affected, and accurate assembly is possible only by ensuring the parallelism between the assembly members, and the bush with flanges. It is also easy to press.

In the above embodiment, the protrusion is formed in an annular shape. However, the protrusion in the present invention does not necessarily have to be a continuous annular shape. For example, a plurality of protrusions symmetrical about the center are formed on the same circumference. Alternatively, the protrusions can be formed on the circumference of multiple stages with different phases.

[Effect of device]

As described in detail above, according to the present invention, only the outer peripheral surface of the tip end portion of the press-fitting shaft or the inner peripheral surface of the press-fitting hole facing the tip end portion of the press-fitting shaft is provided with a narrow protrusion on the surface facing the press-fitting shaft. Since a gap is formed between the shaft and the press-fitting hole from the brim to the protrusion, the perpendicularity between the press-fitting shaft and the brim surface of the bush with brim and the squareness between the inner surface of the press-fitting hole of the first member and the brim seat surface of the first member. Even if the processing accuracy of is not good, the bush with brim is not limited to the surface facing the protrusion not only in the press-fitting process but also after the press-fitting (that is, when a part of the brim is in contact with the seating surface of the first member). Can be oscillated around the contact point of
The levelness between the members can be secured.

Therefore, according to the present invention, the processing cost can be suppressed and the working efficiency can be remarkably improved.

[Brief description of drawings]

FIG. 1 is an exploded sectional view showing an example of an assembling structure to which the present invention is applied, FIGS. 2 and 3 are sectional views of a bush press-fitting structure with a brim showing a different embodiment of the present invention, and FIG. It is sectional drawing which shows the bush press fit structure with a brim. Description of main parts of the drawing 1 …… Bush with collar, 1a …… Brim part 1b …… Press-fit shaft, 1e …… Annular protrusion 2 …… Mating member, 2a …… Bush seat surface 2b …… Press-fit hole, 2d… … Annular step

Continuation of the front page (56) References Open 58-126037 (JP, U) Open 63-129715 (JP, U) Open 60-59857 (JP, U)

Claims (1)

(57) [Scope of utility model registration request] 1. A first member comprising a brim and a cylindrical press-fitting shaft which are fixed in a state of being interposed between a first member and a second member and whose upper surface serves as a seating surface for mounting the second member. In a press-fitting structure having a brim bush formed of a material having higher strength than the brim bush, and press-fitting the press-fitting shaft of the brim-fitting bush into the cylindrical press-fitting hole of the first member, Only the outer peripheral surface or the inner peripheral surface of the press-fitting hole facing the tip of the press-fitting shaft is provided with a narrow protrusion on the surface facing the press-fitting shaft, and between the press-fitting shaft and the press-fitting hole. A press-fitting structure for a bush with a collar, characterized in that a gap is formed over the protruding portion.