JPH07317783A - Fixation structure for tension pulley - Google Patents

Abstract

PURPOSE:To reduce weight and a cost by strongly fixing a bearing having a pulley whose inner diameter is large with width fastening. CONSTITUTION:A bearing 1 having a pulley is fixed to a bracket 2 by means of a bolt 3. An inner ring 4 of the bearing 1 is fitted to a shaft part 2a projected from a bearing engaging stepped surface 2c of the bracket 2. A bearing inner ring 5 is sandwiched between a washer 12 and the bracket stepped surface 2c by fastening a bolt 3 inserted into a bolt hole 10 on a leading end of the shaft part 2a. Length L of the shaft part 2a is reduced compared to a width B of the bearing inner ring by a minute value A deformation rate of the washer 12 is kept low at the time of fastening the bolt 3, and strong fixation can carried out by a regular torque fastening.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tension pulley for applying a tension to an automobile engine belt, and more particularly to a tension pulley fixing structure for fixing a bearing to a bracket with bolts through washers.

[0002]

2. Description of the Related Art Generally,
As a fixing structure of this type of tension pulley, as shown in FIG. 3, a ring member 53 is press-fitted into an inner ring 52 of a bearing 51 with a pulley, and the ring member 53 is fixed to a bracket 55 with a bolt 54. There is. Since the ring member 53 is press-fitted into the bearing inner ring 52, the outer diameter accuracy needs to be strictly controlled. However, since the ring member 53 is an expensive part, there is a problem that the cost becomes high.

For this reason, the width-fastening type fixing structure shown in FIG. 4 (A) may be adopted. This is the bracket 6
1, the shaft portion 61a is integrally projected, the inner ring 63 of the bearing 62 with a pulley is fitted to the shaft portion 61a, and the washer 64 and the bolt 65 are tightened. The shaft portion 61a is
The washer 64 is set to be sufficiently shorter than the inner ring width so that the washer 64 does not come into contact with the tip surface and hinder the tightening of the bearing inner ring 63.
For example, about 0.5 to 1.0 mm, the washer 64 is the shaft portion 61a.
It is set so that it floats from the end face of the. Further, a hexagon bolt with a flange is used as the bolt 65, and the outer diameter of the flange 65a is larger than the inner diameter d of the bearing inner ring 63. As a result, the tightening force of the bolt 65 is directly transmitted to the bearing inner ring 63, and firm fixing is performed. In addition, since expensive parts such as those in the example of FIG. 3 are not used, it can be manufactured at low cost.

However, in this way, the flanged bolt 6
5 can be firmly fixed only when the inner diameter d of the bearing is small, and when the inner diameter d becomes large to some extent, as shown in FIG.
As shown in (B), the outer diameter of the flange 65a of the bolt 65 is smaller than the bearing inner diameter d. Therefore, bolt 6
Since it is not possible to directly pressurize the bearing inner ring 63 with the flange 65a of No. 5, the periphery of the central hole of the washer 64 is pressed, and the washer 64 floats from the tip surface of the shaft portion 61a as described above. Therefore, the washer 64 is excessively deformed as shown in the figure, and sufficient tightening cannot be performed. Further, the washer may be damaged due to excessive deformation of the washer.

If the bolt 65 having a large diameter is used, such a problem is eliminated, but the JIS standard flanged bolt has a maximum size of only M12, and the outer diameter of the flange is 25φ. Become. Therefore, when the bearing inner diameter d is 25φ or more, a bolt having an appropriate diameter cannot be used, which causes a problem of excessive deformation of the washer 64. Further, it is conceivable to thicken the washer 64 to prevent the deformation. In that case, the weight of the washer 64 increases the total weight, and the bolt head may project from the width surface of the pulley 62 depending on the washer thickness. Generally, this kind of tension pulley needs to be housed in a narrow space, and if the bolt head projects, it may interfere with peripheral devices and covers. Therefore, for the bearing with a pulley having a large bearing inner diameter, the width tightening structure of FIG. 4 cannot be taken, and the ring member 5 of FIG.
Inevitably, the structure used is No. 3, which is an expensive fixed structure.

It is an object of the present invention to firmly fix a bearing with a pulley having a large bearing inner diameter in a width tightening type,
An object of the present invention is to provide a tension pulley fixing structure that is lightweight and cost-effective.

[0007]

In the tension pulley fixing structure of the present invention, the inner ring of the pulley bearing is fitted to the shaft portion protruding from the bearing engaging step surface of the bracket, and the tip end surface of the shaft portion is fixed. It is applied to a fixing structure in which the bearing inner ring is sandwiched between the washer and the step surface which are interposed on the back side of the bolt head by tightening the bolt inserted in the bolt hole.
In this fixing structure, the length of the shaft portion of the bracket is made smaller than the inner ring width of the bearing by a minute length. The bracket is made of a light alloy casting, for example.

[0008]

[Function] When the bearing is fitted to the shaft portion of the bracket and the washer is covered and the bolt is tightened, when the bolt is tightened with the specified torque, the washer is deformed by a gap between the shaft portion of the bracket and the shaft portion. Contact the tip surface of the part. The gap is the difference between the length of the shaft portion and the width of the inner ring of the bearing, and since it is set to a minute length, the washer does not cause excessive deformation,
The inner ring of the bearing can be firmly fixed by tightening the bolt with the specified torque.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. This tension pulley has a structure in which a bearing 1 with a pulley is fixed to a bracket 2 with bolts 3 as shown in FIG. A bearing 1 with a pulley has a pulley main body 7 fixed to the outer circumference of an outer ring 6 of a rolling bearing 4, and a deep groove ball bearing with a seal or the like is used for the rolling bearing 4. The bracket 2 is made of a light alloy such as aluminum, and has a bolt 8 at the base end for a casing of an automobile engine.
And a shaft portion 2a extending in parallel to the mounting hole 9 is formed on the tip side. A portion 2b near the shaft portion 2a of the bracket 2 is formed into a round shaft shape having a diameter slightly larger than that of the shaft portion 2a, and a bearing engaging step surface 2c is formed between the shaft portion 2a and the shaft portion 2a. A bolt hole 10 penetrates through the shaft portion 2a of the bracket 2 in the center thereof, and a counterbore portion 10a for fitting a nut 11 is provided in the bolt hole 10 at an opening opposite to the shaft portion 2a.

In the bearing 1 with pulley, the inner ring 5 is fitted to the shaft portion 2a of the bracket 2, and the bolt 3 inserted into the bolt hole 10 is screwed into the nut 11 to be tightened. As a result, the bearing inner ring 5 is sandwiched and fixed between the washer 12 and the step surface 2c of the bracket 2 which are interposed on the back surface of the bolt head 3a. As the bolt 3, a hexagon bolt with a flange is used. The inner diameter of the bearing is, for example, about 30 mm, and the bolt 3
In this case, the outer diameter of the flange 3b is smaller than the inner diameter of the bearing. As shown in FIG. 1A, the length L of the shaft portion 2a of the bracket 2 is set to be shorter than the width B of the bearing inner ring 5 by a minute length α. The minute length α is set to be 0.4 mm or less and larger than zero. That is, the length α is set to be sufficiently shorter than the length of 0.5 to 1.0 mm normally provided.

According to the fixing structure of this structure, when the inner ring 5 of the bearing 1 with a pulley is fitted into the shaft portion 2a of the bracket 2 (FIG. 1 (A)), a gap between the tip end surface of the shaft portion 2a and the washer 12 is formed. Becomes the above-mentioned minute length α. When the bolt 3 is tightened, the washer 12 is deformed by the above-mentioned gap, and the shaft portion 2a
(Fig. 1 (B)). The gap is a minute length α
Therefore, the amount of deformation of the washer 12 can be suppressed low. Therefore, the washer 12 does not deform excessively and the bolt 3
The inner ring 5 can be firmly fixed with. in this way,
The bearing 1 with a pulley with a large inner diameter can be tightened firmly,
It is not necessary to make the washer 12 thick, and the weight can be reduced. Further, it is not necessary to use an expensive material such as a ring member, so that the cost can be reduced. Further, since the bracket 2 is made of a cast of light alloy such as aluminum, the weight can be further reduced and the dimensional accuracy of the shaft portion 2a can be easily obtained.

[0012]

The tension pulley fixing structure of the present invention is a fixing structure in which the inner ring of the pulley bearing is fitted to the shaft portion of the bracket and is sandwiched between the bolt and the step surface of the bracket through a washer. Since the length of the shaft portion is set to be a minute length shorter than the inner ring width of the bearing, it is possible to firmly tighten the width of a bearing with a pulley having a large inner diameter without using a thick washer, and to reduce the weight and cost. Can be planned. Further, since the bracket is made of a light alloy casting, the weight can be further reduced and the dimensional accuracy of the shaft portion can be easily obtained.

[Brief description of drawings]

FIG. 1 is a partial sectional view showing a state before and after tightening a bolt of a tension pulley fixing structure according to an embodiment of the present invention.

FIG. 2 is a sectional view of the tension pulley in an exploded state.

3A is a sectional view of a conventional example, and FIG. 3B is a front view thereof.

4A is a sectional view of a conventional example, and FIG. 4B is a sectional view of a proposed example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Bearing with pulley, 2 ... Bracket, 2a ... Shaft part, 2
c ... step surface, 3 ... bolt, 4 ... rolling bearing, 5 ... inner ring, 1
2 ... Washer, B ... Bearing width, L ... Shaft length, α ... Minute length

Claims (1)

[Claims] 1. An inner ring of a bearing with a pulley is fitted to a shaft portion protruding from a bearing engaging step surface of a bracket, and a bolt inserted in a bolt hole in a tip end surface of the shaft portion is tightened to fix a bolt head. In the fixing structure in which the bearing inner ring is sandwiched between the washer and the step surface interposed on the back side, the length of the shaft portion of the bracket is made smaller than the inner ring width of the bearing by a minute length, and the bolt A tension pulley fixing structure in which the washer is slightly deformed to come into contact with the tip end surface of the shaft portion in a tightened state with a specified torque.