JP2015189285A - Wheel installing structure - Google Patents

Abstract

The present invention improves the fastening and fixing performance when a bolt and a nut are fastened to a hub to press and fix a wheel. An annular groove portion 16 including an attachment hole 15a is provided on an attachment surface 15c of a wheel 15 by a nut 12 at an asymmetric position where the center of the groove width does not coincide with the center of the attachment hole 15a. The distance from the groove 16 to the outer side wall 16a is made shorter than the distance from the center of the mounting hole 15a to the inner side wall 16b of the groove 16. As a result, the contact surface 15b of the wheel 15 is used as an inner and outer double ring-shaped contact region, so that the bolt axial force can be more distributed to the outer contact region, and the contact surface pressure of the inner contact region is relative. Therefore, it is possible to improve the fastening and fixing performance. [Selection] Figure 1

Description

  The present invention relates to a wheel mounting structure in which a bolt and a nut are fastened to a hub provided at a shaft end to press and fix a wheel.

  2. Description of the Related Art Generally, in a vehicle such as an automobile, a mounting structure in which a wheel is press-fixed to a hub by fastening bolts and nuts is adopted as a wheel mounting structure to a hub provided at an end of an axle.

  For example, in Patent Document 1, a bolt is press-fitted and fixed to a flange of an inner ring member to which a brake member is attached, a wheel member is attached to a foot portion of the bolt protruding from the flange, and screwed with a screw portion formed on the foot portion of the bolt. A fastening structure is disclosed in which a wheel member is pressed against and fixed to a side surface of a flange by a nut.

  In the fastening structure disclosed in Patent Document 1, a continuous groove portion including the peripheral edge is formed on the periphery of the bolt hole on the side surface of the flange with which the wheel member contacts, and the bolt hole is positioned in the groove portion. The mounting accuracy can be improved by suppressing the undulation of the flange side surface when the bolt is press-fitted and fixed in the bolt hole formed in the above.

JP-A-7-164809

  However, in the conventional wheel mounting structure disclosed in Patent Document 1 by fastening bolts and nuts, the surface pressure distribution of the pressure contact fixing surface of the wheel is unevenly distributed only around the bolts. For this reason, the surface pressure tends to be relatively small on the outer diameter side of the mounting diameter from the center of the wheel to the center of the bolt hole, and the fastening force tends to be weakened. There is room.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a wheel mounting structure capable of improving the fastening and fixing performance when a wheel and a nut are fastened to a hub by press-fitting and fixing the wheel. .

  The wheel mounting structure according to the present invention is a wheel mounting structure in which a bolt and a nut are fastened to a hub provided at an end of a shaft to press and fix the wheel, and the wheel is mounted on the side opposite to the hub side pressing contact fixing surface. An annular groove portion including an attachment hole through which the bolt is inserted is formed on the surface, and the groove width center of the groove portion is disposed at an asymmetric position where it does not coincide with the center of the attachment hole.

  According to the present invention, it is possible to improve the fastening and fixing performance when the bolt and the nut are fastened to the hub and the wheel is pressed and fixed.

Cross section of the main part of the wheel mounting part Explanatory drawing which shows the flange part of the hub main body seen from A arrow of FIG. Explanatory drawing showing the surface pressure distribution on the contact surface of the wheel Explanatory drawing showing the relationship between mounting hole center and groove position Explanatory drawing showing distribution of center of surface pressure

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows an attachment portion of a wheel 15 attached to a hub unit 1 provided at an axle end portion of a vehicle such as an automobile. In FIG. 1, a cross section of a main part near the center portion of the hub unit 1 and the wheel 15 is shown. Show. The hub unit 1 includes a hub body 2 to which a braking disk rotor 10 and a wheel 15 to which tires (not shown) are attached are attached, and a housing 6 that rotatably supports the hub body 2 via a bearing 5. And. The bearing 5 is sealed inside by an oil seal 7. The housing 6 is connected to the suspension device or constitutes a part of the suspension device.

  The disk rotor 10 is attached to an annular flange portion 3 provided at the end of the hub body 2 via hub bolts 11. As shown in FIG. 2, a plurality of (for example, five) bolt holes 4 penetrating in the axial direction at equal intervals on the circumference are formed in the flange portion 3, and hub bolts 11 are formed in the bolt holes 4. It is press-fitted from the housing 6 side and fixed by serration coupling.

  The disk rotor 10 is provided with a mounting hole 10a through which the shaft portion 11a of the hub bolt 11 protruding from the flange portion 3 is inserted. Further, the wheel 15 is provided with an attachment hole 15a through which a screw portion 11b that is formed to have a slightly smaller diameter than the shaft portion 11a of the hub bolt 11 and extends from the shaft portion 11a is inserted.

  The disc rotor 10 and the wheel 15 have mounting holes 10a and 15a inserted through the shaft portion 11a and the screw portion 11b of the hub bolt 11 and mounted on the flange portion 3 of the hub body 2, and a nut 12 is screwed into the screw portion 11b. It is tightened together. Thereby, the disk rotor 10 is pressed and fixed to the side surface 3 a of the flange portion 3, and the wheel 15 is pressed and fixed to the side surface 3 a of the flange portion 3 via the disk rotor 10.

  Here, with respect to the contact surface 15b to the disc rotor 10 which is the pressure contact surface of the wheel 15 on the hub body 2 side, the mounting surface 15c by the nut 12 on the side opposite to the contact surface 15b includes a mounting hole 15a. An annular groove 16 is provided. The groove portion 16 is formed as a belt-like concave portion on the circumference on the mounting surface 15c side, and the mounting hole 15a is opened at the bottom surface of the concave portion of the groove portion 16 and is disposed so as to be recessed in the axial direction from the mounting surface 15c.

  When the nut 12 is fastened and the wheel 15 is fixed to the hub body 2 by the groove portion 16, the groove portion 16 can be fixed with a more stable and uniform fastening force as compared with a conventional wheel that does not have the groove portion 16. Next, the attachment structure of the wheel 15 to the hub body 2 by the groove 16 will be described.

  In the conventional wheel mounting structure that does not have the groove 16 on the mounting surface to which the nut 12 is fastened, the surface pressure distribution on the contact surface of the wheel that contacts the disk rotor 10 is around the hub bolt 11 as shown in FIG. The distribution is concentrated locally in the region Pb, and there is a possibility that a stable fastening force cannot be obtained at a position away from the region Pb. On the other hand, in the wheel 15 according to the present invention, as shown in FIG. 3 (b), the surface pressure distribution of the contact surface 15b that contacts the disk rotor 10 due to the presence of the groove portion 16 is outside the mounting hole 15a. The annular contact area Pout and the inner annular contact area Pin are distributed in a double ring shape, and the wheel 15 can be fixed to the hub body 2 with a more stable and uniform fastening force.

  In this case, the groove portion 16 is formed at an asymmetrical position where the center of the groove width does not coincide with the center of the attachment hole 15a with respect to the attachment hole 15a. In the present embodiment, the distance D1 to the outer side wall portion 16a of the groove portion 16 and the distance D2 to the inner side wall portion 16b of the groove portion 16 are set different from each other with the center of the mounting hole 15a as a reference. In addition, the groove portion 16 is disposed at a position where the relationship of D1 <D2 is satisfied. Thus, the contact between the outer contact area Pout and the inner contact area Pin of the contact surface 15b is established by offsetting the groove width center of the groove portion 16 asymmetrically with respect to the center of the mounting hole 15a. The difference in surface pressure can be eliminated.

  Hereinafter, the surface pressure distribution of the contact surface 15b will be described based on an analysis result obtained by an analysis model in which the contact surface 15b is divided into grid-like regions partitioned by a radial direction and a circumferential direction. This analysis model is a simple model for calculating contact stress for each region when a load corresponding to the axial force at the time of bolt fastening is applied.

  When the surface pressure component of the contact surface 15b is examined using the analysis model, as shown in FIG. 4A, the contact regions Pout and Pin of the contact surface 15b are not annular regions but linear shapes having no curved portions. In the case of the region, there is no difference in the contact surface pressure between the contact regions Pout and Pin. On the other hand, as shown in FIG. 4B, when the contact areas Pout and Pin of the contact surface 15b are annular areas, the center of the mounting hole 15a and the center of the groove width coincide with each other. If the groove is formed at the position, a difference occurs in the contact surface pressure between the contact areas Pout and Pin.

  That is, when the grooves are formed at symmetrical positions where the center of the mounting hole 15a and the center of the groove width coincide with each other in the same radial lattice region, as shown in FIG. In a linear contact region having no contact distance, the distance do from the center of the mounting hole 15a to the lattice region outside the contact surface 15b, and from the center of the mounting hole 15a to the lattice region inside the contact surface 15b. The distance di is equal, and the contact surface pressure is uniform in the outer region Pout and the inner region Pin.

  On the other hand, as shown in FIG. 4B, in the annular contact region, when the groove is formed at a symmetrical position where the center of the groove width coincides with the center of the attachment hole 15a, the hole of the attachment hole 15a is formed. The distance di from the center of the mounting hole 15a to the lattice region inside the contact surface 15b is smaller than the distance do from the center of the contact surface 15b to the lattice region outside the contact surface 15b, and the contact surface of the outer region Pout The contact surface pressure in the inner region Pin is higher than the pressure. This is because there is a difference in the distances di and do from the center of the mounting hole 15a to the inner and outer lattice regions, and the axial force at the time of bolt fastening is not evenly distributed to the inner and outer contact regions. A difference is considered to occur.

  Therefore, in the present embodiment, the distance D1 from the center of the mounting hole 15a to the side wall portion 16a outside the groove portion 16 is shorter than the distance D2 from the center of the mounting hole 15a to the side wall portion 16b inside the groove portion 16. By doing so, the above-mentioned distance do is further reduced. As a result, more bolt axial force can be distributed to the outer contact area Pout, and the contact surface pressure of the inner contact area Pin is prevented from becoming relatively high, and the contact surface pressure of the contact areas Pout, Pin is reduced. Can be made uniform.

  In this case, the groove portion 16 is set to an appropriate value as well as the center position of the groove width, and the contact region Pout outside the contact surface 15b and the side surface of the flange portion 3 of the hub body 2 with the disk rotor 10 interposed therebetween. 3a is set so as to always wrap with a predetermined width (for example, a width of 1 mm at a minimum). By providing such a lap portion that overlaps with the outer peripheral portion of the hub body 2 in the radial direction, it is possible to avoid the concentration of shearing load on the disk rotor 10 at the boundary portion outside the flange portion 3 of the hub body 2. The durability of the disk rotor 10 can be improved.

  FIGS. 5A and 5B show the distribution of the surface pressure center of the wheel 15 calculated using the above analysis model. In this surface pressure distribution, a plurality of lattice regions arranged in the radial direction are set as one group, and each group around the mounting hole 15a is defined as 1 to 13, and the position of the surface pressure center for each group is determined from the wheel center. It is represented by a distance H.

  The surface pressure center is indicated by the position of the region closest to the average value of the contact stresses of a plurality of lattice regions in one group, and the center of the mounting hole 15a and the center of the groove width of the groove portion 16 coincide with each other. The center of the surface pressure is indicated by a solid line, and the center of the surface pressure when the center of the groove width of the groove portion 16 is offset radially inward from the center of the mounting hole 15a is indicated by a broken line. FIG. 5B shows an enlarged distance H from the wheel center at the surface pressure center near the mounting hole 15a.

  5A and 5B, the center of the mounting hole 15a is centered on the surface pressure (solid line in the figure) when the center of the mounting hole 15a and the center of the groove width of the groove portion 16 coincide. On the other hand, it can be seen that the center of the surface pressure (broken line in the figure) when the center of the groove width of the groove portion 16 is offset radially inward is shifted to the outer diameter side. That is, when the wheel 15 of the present embodiment in which the center of the groove width of the groove portion 16 is offset radially inward with respect to the center of the mounting hole 15a is fastened and fixed to the hub body 2, the disk rotor 10 of the wheel 15 is fixed. It can be seen that the axial force of the hub bolt 11 acts more on the outer annular region Pout at the contact surface 15b.

  As described above, in the present embodiment, the annular groove portion 16 including the attachment hole 15a through which the hub bolt 11 is inserted is provided on the attachment surface 15c of the wheel 15 attached to the hub body 2, and the groove width center of the groove portion 16 is attached. It is formed offset from the center of the hole 15a radially inward.

  As a result, the contact surface 15b on the disk rotor 10 side is used as an inner and outer double ring-shaped contact region, and the surface pressure of the inner contact region is relatively increased by increasing the surface pressure of the outer contact region. The wheel 15 can be stably fixed to the hub body 2 on the outer diameter side, and the fastening and fixing performance of the wheel 15 can be improved. Further, by improving the fastening and fixing performance of the wheel 15, the delay time of the yaw rate with respect to the steering angle, the rigidity of the suspension can be increased, the unsprung load can be reduced, and the like, which can contribute to the improvement of the steering stability. .

  In the present embodiment, the wheel 15 has been described as being fastened and fixed by fastening the nut 12 to the hub bolt 11 fixed to the hub main body 2, but the wheel 15 is provided with a female screw on the hub side. An attachment form in which the bolt is fastened and fixed to the hub may be used.

DESCRIPTION OF SYMBOLS 1 Hub unit 2 Hub main body 3 Flange part 3a Side surface 10 Disc rotor 11 Hub bolt 12 Nut 15 Wheel 15a Mounting hole 15b Contact surface (pressure contact fixing surface)
15c Mounting surface 16 Groove

Claims (3)

In the wheel mounting structure that fastens the wheel by fastening bolts and nuts to the hub provided at the shaft end,
An annular groove portion including an attachment hole through which the bolt is inserted is formed on the attachment surface on the opposite side to the pressure-contact fixing surface on the hub side of the wheel, and the groove width center of the groove portion does not coincide with the center of the attachment hole. A wheel mounting structure characterized by being disposed at an asymmetric position.   The wheel mounting structure according to claim 1, wherein a groove width center of the groove portion is disposed so as to be located radially inward from a center of the mounting hole.   3. The wheel mounting structure according to claim 1, wherein the groove portion is disposed on a pressure contact fixing surface of the wheel on the hub side so that a lap portion that overlaps with an outer peripheral portion of the hub in a radial direction is generated.

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