JP7269063B2 - brake disc - Google Patents

Description

TECHNICAL FIELD The present invention relates to a brake disc used in a vehicle such as a railway vehicle, and more particularly to a technique for reducing stress generated in fastening bolts due to frictional heat during braking.

Disc brakes used for braking railway vehicles and automobiles generate braking force by pressing brake pads against brake discs that rotate with axles and wheels, thereby braking the rotation of axles or wheels to control vehicle speed. known to do.

High-speed railway vehicles such as bullet trains are being driven at speeds exceeding 300 km/h as speed increases are being promoted.

In the brake disc of Patent Literature 1, the ratio of the total volume of the fastening portion and the non-fastening portion is specified to prevent strain from concentrating on one portion, thereby suppressing warpage and undulation.

In Patent Document 2, by optimizing the positional relationship between the contact position with the wheel on the inner and outer circumferences of the brake disc and the fastening hole, the bending load on the bolt is reduced and the durability of the bolt is ensured. .

Further, in the brake disc of Patent Document 3, a donut-shaped disc portion having a sliding surface on the front side thereof, a plurality of radial fin portions protruding radially from the back surface of the disc portion, and a disc portion and bolt holes penetrating the radial fin portion are provided, and the disk portion is attached to the wheel with the radial fin portion pressed against the plate portion of the wheel by fastening with bolts inserted through the bolt holes. In this radial fin portion, grooves are formed along the circumferential direction in the radially inner and outer peripheral regions sandwiching the bolt hole, thereby improving the cooling performance during braking and braking. I'm trying to improve the durability of the disc.

JP-A-2005-321091 JP-A-2006-9862 Japanese Patent No. 5924413

For example, according to the brake discs disclosed in Patent Documents 1 to 3, when emergency braking is applied from a high-speed running state, the brake disc deforms due to thermal expansion, and the stress load on the fastening bolts increases accordingly. There is a tendency.

In this way, brake discs specify a method for coping with the thermal stress that occurs, but the durability of the bolt can be improved by further reducing the stress that occurs in the fastening bolt.

SUMMARY OF THE INVENTION It is an object of the present invention to further reduce the stress generated in the fastening bolts of the brake disc due to frictional heat during braking.

In order to achieve the above object, the present invention suppresses the stress generated in the fastening bolts of the brake disc due to frictional heat.

Specifically, in the first invention,
A doughnut-shaped disk-shaped plate portion having a sliding surface on the surface side;
a plurality of bolt fastening fins projecting from the rear surface of the plate portion so as to extend radially at intervals, and fastened to the wheel by inserting fastening bolts into bolt insertion holes provided in the middle in the longitudinal direction; with
A stress avoidance gap is formed between the bolt fastening fin portion and the contact surface of the wheel on the radially inner side or the radially outer side of the bolt insertion hole.

That is, the frictional heat causes the brake disc to be deformed so as to swell to the side opposite to the wheel, so stress is applied in the direction of pulling the fastening bolt starting from the point of contact with the contact surface of the wheel. However, according to the above configuration, the stress avoidance gap is intentionally secured between the contact surface of the wheel on the radially inner side or the radially outer side of the bolt insertion hole, so that the brake disc is deformed by frictional heat. However, only the portion near the bolt through-hole abuts against the wheel in the portion with the stress avoidance gap, making it difficult to generate a force that applies a tensile load to the fastening bolt. Therefore, the durability of the fastening bolt is improved.

In the second invention, in the first invention,
A plurality of radial fins projecting from the back surface of the plate portion so as to radially extend at intervals between the plurality of bolt fastening fin portions, and substantially entirely in contact with the contact surface of the wheel in the radial direction. It also has a part.

According to the above configuration, the radial fin portion easily secures the contact pressure between the fastening bolt and the contact surface of the wheel, etc. without imposing a burden on the fastening bolt, and the heat dissipation effect is also easily improved.

In a third invention, in the first or second invention,
The bolt fastening fin portion has an end portion arranged radially inwardly from the center of the bolt insertion hole by 20 mm or more and 35 mm or less, or an end portion is arranged radially outwardly by 15 mm or more and 35 mm or less.

According to the above configuration, by providing the stress avoidance gap in the optimum range, the stress applied to the fastening bolt can be appropriately reduced compared to the conventional case where the bolt fastening fin portion abuts on the wheel in the entire radial direction. can be reduced.

As described above, according to the present invention, the stress avoidance gap is formed between the contact surface of the wheel on the radially inner side or the radially outer side of the bolt insertion hole in the bolt fastening fin portion, thereby improving the braking performance. It is possible to reduce the stress generated in the fastening bolts of the brake disc due to the frictional heat inside.

FIG. 5 is an enlarged front view of part I in FIG. 4 ; 1 is a front view showing a wheel to which a brake disc according to an embodiment of the invention is fastened; FIG. 3 is a cross-sectional view taken along line III-III of FIG. 2; FIG. It is a rear view showing the back of the brake disc concerning the embodiment of the present invention. 5 is a table showing analysis results of stress applied to the fastening bolts according to Example 1 and Comparative Example 1 when the positions of the inner peripheral side tip positions of the bolt fastening fin portions are changed. 9 is a table showing measured values of stresses applied to the fastening bolts of Example 2 and Comparative Example 2 when the tip position on the inner peripheral side of the bolt fastening fin portion is 35 mm. FIG. 11 is a table showing analysis results of stress applied to the fastening bolts according to Example 3 and Comparative Example 3 when the positions of the ends of the bolt fastening fins on the outer peripheral side are changed; FIG. FIG. 1 is a view equivalent to FIG. 1 according to Example 3 of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

1 to 4 show a brake disc 1 for a railroad vehicle according to an embodiment of the present invention. This brake disc 1 is provided on both front and back surfaces of a disk portion 20a of a wheel 20 of a railroad vehicle, for example, as fastening bolts. are detachably attached by means of a fastening bolt 21 and a fastening nut 22, respectively. The brake disc 1 is made of cast steel, for example.

The brake disc 1 includes a doughnut-shaped plate portion 1a having a circular opening in the center and having a surface side (outer side surface) as a sliding surface. A plurality of bolt fastening fin portions 2 are integrally protruding from the rear surface (inner side surface) of the plate portion 1a at intervals. The brake disc 1 is fastened to the wheel 20 by inserting the fastening bolt 21 into the bolt insertion hole 2a provided in the middle of each bolt fastening fin portion 2 in the longitudinal direction. In this embodiment, a total of 12 bolt fastening fins 2 are provided at intervals of 30°. In addition, this number is not necessarily limited to 12, and may be more or less.

In this embodiment, a total of 12 radial fin portions 3, for example, one between each pair of bolt fastening fin portions 2, are integrally protruded from the disc portion 20a so as to extend radially. The thickness of the radial fin portion 3 is the same as the thickness of the bolt fastening fin portion 2, but it may be thinner or thicker than the bolt fastening fin portion. Further, the number of fins is not necessarily limited to that of this embodiment, and may be more or less, and the radial fin portion 3 may be omitted. Note that the presence of the radial fins 3 makes it easier to secure the surface pressure between the fastening bolts 21 and the contact surfaces of the wheels 20 without putting a burden on them, and it is easy to improve the heat dissipation effect.

Incidentally, on the back surface of the plate portion 1a, inclined fin portions may protrude at a predetermined inclination angle on both sides of the bolt fastening fin portion 2 in the circumferential direction.

As shown in FIG. 3 , the pair of brake discs 1 sandwich the disk portion 20a of the wheel 20 from both sides in the thickness direction thereof, and are for fastening to fastening bolts 21 inserted through the bolt insertion holes 2a. By fastening the nut 22, it is detachably fixed to the wheel 20. - 特許庁

In this embodiment, as shown in an enlarged view in FIG. 1, the bolt fastening fin portion 2 is positioned radially inside the bolt insertion hole 2a between the contact surface of the wheel 20 while being fixed to the wheel 20. A stress avoidance gap 5 is formed in the .

As shown in an enlarged view in FIG. 3, the bolt fastening fin portion 2 is not in contact with the disk portion 20a at all in the stress avoidance gap 5 provided inside the inner peripheral side tip position x1.

That is, since the brake disc 1 tends to be deformed so as to swell in the opposite direction to the wheel 20 due to frictional heat, the direction in which the fastening bolt 21 is pulled from the point of contact with the contact surface of the disk portion 20a of the wheel 20 is the starting point. is stressed.

However, in this embodiment, as shown enlarged in FIG. 3, a stress avoidance gap 5 is intentionally secured between the contact surface of the disk portion 20a and the radially inner side of the bolt insertion hole 2a. Therefore, even if the brake disc 1 is deformed by frictional heat, only the portion near the bolt through hole 2a contacts the wheel, and the portion with the stress avoidance gap 5 is pulled against the fastening bolt 21. It becomes difficult to generate the force that applies the load. Therefore, the durability of the fastening bolt 21 is improved.

-Example 1-
In the brake disc 1 of the above embodiment, the wheel diameter of 860 mm and the outer diameter of the brake disc 1 of 720 mm are assumed as Example 1. In the first embodiment, it is assumed that the stress avoiding gap 5 is provided with the inner circumference side tip position x1 set to x1=15 mm to 40 mm.

As Comparative Example 1, a brake disc 101 having the same size and having the bolt fastening fin portion 2 and the radial fin portion 3 in contact with the contact surface of the disc portion 20a of the wheel 20 substantially in the entire radial direction is assumed. The fastening bolt 21 used has a shaft diameter of 16 mm, and the analysis was performed under the conditions of applying 370 MPa as an initial tightening force.

Fig. 10 shows the result of analysis by the finite element method of the stress generated in the fastening bolt 21 when the vehicle having Example 1 and Comparative Example 1 applies the emergency brake once at a speed of 300 km/h. 5.

"Maximum" in FIG. 5 represents the maximum stress generated in the bolt during braking, and "fluctuating stress" represents the stress amplitude generated in the fastening bolt during braking.

This analysis result revealed that the maximum stress and the fluctuating stress were reduced by 3.5% or more compared to Comparative Example 1, especially when the inner circumference side tip position x1 was 20 mm to 35 mm.

-Example 2-
In Example 2, brake discs 1 and 101 of the same size as in Example 1 were used. A bench test was performed for the position x1=35 mm. The results are shown in FIG.

As can be seen from FIG. 6, it was found that the maximum stress and fluctuating stress were reduced in the bench test as well as in the analysis.

-Example 3-
In Example 3, unlike the above embodiment, as shown in FIG. 8, a stress avoiding gap 5' is formed by providing an end portion at x3=15 mm to 40 mm radially outward of the bolt fastening fin portion 2'. An analysis was performed on the brake disc 1'.

Specifically, Example 3 was assumed to have a wheel diameter of 860 mm, an outer diameter of the brake disc 1 of 720 mm, and a change in the outer peripheral side tip position x3. FIG. 7 shows the result of comparing a brake disc similar to Comparative Example 1 as Comparative Example 3. In FIG.

As shown in FIG. 7, it was found that the maximum stress and the fluctuating stress were reduced by 3.5% or more compared to Comparative Example 3 when x3=15 mm or more and 35 mm or less.

The above embodiments are essentially preferable examples, and are not intended to limit the scope of the present invention, its applications, or uses.

For example, in Examples 1 and 2, the stress avoidance gap 5 was formed only radially inward, and in Example 3, the stress avoidance gap 5' was formed only radially outward. A stress avoidance gap 5, 5' may be formed.

1 brake disc
1a plate
2, 2' bolt fastening fins
2a bolt insertion hole
3 radial fins
5,5' stress avoidance clearance
20 wheels
20a disk part
21 fastening bolt
22 fastening nut

Claims (1)

A doughnut-shaped disk-shaped plate portion having a sliding surface on the surface side;
a plurality of bolt fastening fins projecting from the rear surface of the plate portion so as to extend radially at intervals, and fastened to the wheel by inserting fastening bolts into bolt insertion holes provided in the middle in the longitudinal direction; with
A stress avoidance gap is formed between the bolt fastening fin portion and the contact surface of the wheel on the radially inner side or the radially outer side of the bolt insertion hole ,
A plurality of radial fins projecting from the back surface of the plate portion so as to radially extend at intervals between the plurality of bolt fastening fin portions, and substantially entirely in contact with the contact surface of the wheel in the radial direction. furthermore has a part
A brake disc characterized by:

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