JP2000170805A - Brake disc for rolling stock - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the brake disc for a rolling stock which can prevent the generation of an excessive thermal stress, even if it is used for an emergency during a high speed running. SOLUTION: By providing the clearance 9 of 0.2-1.5 mm between the tip of a fin 6 and a wheel 2 side surface and escaping the thermal expansion by an excessive heat on a slide surface 4 to the thickness direction of the disc 1, the thermal stress of a periphery direction is relieved and the generation of a crack and deformation are prevented. By minimizing the escape of the slide surface 4 by the push-press force of a pad 5, the friction coefficient on the slide surface 4 can be maintained to a high value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an integrated brake disk for a railway vehicle.

[0002]

2. Description of the Related Art Electric brakes and mechanical brakes are used as brakes for railway vehicles, and disc brakes are often used as mechanical brakes. Usually, an electric brake is used for deceleration from a high speed, and a disc brake is used after deceleration to some extent. However,
When a trouble in the electric system occurs for some reason during running and the electric brake becomes unusable, it is necessary to use the disc brake even during high-speed running.

[0003] There are two types of disc brakes, one of which is mounted on the side of a wheel and the other of which is mounted on an axle. The disc brake of which is mounted on the side of a wheel utilizes a space on the side of the wheel and stores a brake disc in this space. Due to the system, a compact design can be achieved.

[0004] There are two types of brake disks: an integral type in which the disk is integrally formed, and a split type in which the disk is divided into a plurality of sector shapes. The split-type disk has the advantage that thermal stress due to frictional heat generated when a brake is applied can be reduced, and it is not necessary to remove the wheel from the axle when installing, and it is easy to replace. However, there is a disadvantage that the pad is easily worn out by a slight step generated at the same time, and a loud noise is generated. The integrated disk has the advantage that the sliding surface can be formed flat, the life of the pad can be prolonged, the noise can be reduced, and the processing can be simplified and the manufacturing cost can be reduced, but the thermal stress increases.

As described above, since the split-type disk has low thermal stress, cast iron or a particle-dispersed aluminum alloy casting, which is inferior in toughness but excellent in sliding characteristics, is usually used as a material thereof. On the other hand, cast steel or forged steel excellent in toughness is usually used for an integrated disk having a large thermal stress.

FIG. 5 shows a conventional integrated brake disc. This brake disc is a pair of two discs 1
The pair of disks 11 is fastened to both sides of the wheel 12 by bolts 13. Each disk 11
A flat sliding surface 14 is provided on the front surface side, and fins 15 for heat radiation are provided on the rear surface side. Pads 16 are pressed from both sides of each sliding surface 14.

Each of the disks 11 needs to be reduced in thickness in order to fit in the limited space on the side surface of the wheel 12, and the disk 11 escapes to the side surface of the wheel 12 by elastic deformation due to the pressing force of the pad 16. The tips of the fins 15 are designed to substantially contact the side surfaces of the wheel 12 so that the frictional force between the sliding surface 14 and the pad 16 does not decrease.

[0008]

The above-mentioned conventional integrated brake disc has a problem that when it is used for emergency in a high-speed running state due to the above-mentioned troubles, cracks and deformations occur due to thermal stress due to excessive heat generation. is there.

That is, when the disk thermally expands due to excessive heat generation on the sliding surface, the compressive stress in the circumferential direction is applied to the outer peripheral side of the disk provided with the sliding surface, and the inner peripheral side of the disk provided with the fastening bolt holes. In this case, tensile stress is generated in the circumferential direction. As described above, in the conventional disk, since the rear surface side on which the fins are provided is constrained in the thickness direction by the wheel side surface, the absolute values of the compressive stress and the tensile stress in the circumferential direction increase.

When the tensile stress becomes excessive, cracks are generated starting from the inner peripheral end face of the disk or the fastening bolt hole where the stress tends to concentrate. These cracks grow due to repeated thermal stress and may lead to disk breakage. When the toughness of the disk material is high, thermal deformation occurs instead of cracks, and the contact with the pad becomes uneven. In extreme cases, the disc will always come into contact with the pad, forcing it to be replaced.

SUMMARY OF THE INVENTION An object of the present invention is to provide a railway vehicle brake disc which can prevent the occurrence of excessive thermal stress even when used for emergency during high-speed running.

[0012]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is directed to a vehicle equipped with a pad mounted on both sides of a wheel of a railway vehicle, a sliding surface with a pad on the front side, and a radiating fin on the back side. In a brake disc for a railway vehicle comprising a pair of discs provided with a pair of discs, a configuration is provided in which a gap of 0.2 to 1.5 mm is provided between the tip of the fin and the side face of the wheel.

That is, by providing a small gap between the tip of the fin and the side of the wheel, thermal expansion due to excessive heat generation on the sliding surface is released in the thickness direction of the disk, and the heat of compression and tension in the circumferential direction is reduced. The stress can be reduced. The lower limit of the gap is 0.2 mm and the upper limit is 1.5 mm
Is determined based on the brake test results described below. If the gap is less than 0.2 mm, the thermal stress cannot be sufficiently reduced, and if it exceeds 1.5 mm, the disc is pushed to the wheel side by the pressing force of the pad. Escape and frictional force with the pad on the sliding surface cannot be sufficiently secured.

By forming the gap so as to be larger toward the outer periphery of the disk, a radial gradient of the circumferential thermal stress can be further reduced.
That is, since the amount of heat generated on the sliding surface is larger on the outer peripheral side where the sliding distance is longer, the amount of thermal expansion becomes larger on the outer peripheral side of the disk. The change in the gap in the radial direction can be tapered, stepped, or the like.

By forming the disk from cast iron or a particle-dispersed aluminum alloy casting, the sliding characteristics on the sliding surface can be improved.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. This brake disc is shown in FIG.
As shown in FIG. 2, the disk 1 comprises a pair of discs 1 made of a cast aluminum alloy with SiC particles dispersed therein.
Are housed in spaces formed on both sides of the side surface of the wheel 2 and are fastened with bolts 3. A flat sliding surface 4 is provided on the surface side of each disk 1, and pads 5 are pressed from both sides of each sliding surface 4.

As shown in FIGS. 2 and 3, a large number of heat dissipating fins 6 are provided radially on the back surface of the disk 1, and on the inner peripheral side of these fins 6, the fastening bolts 3 are provided. Hole 7 is provided. In the outermost part,
A flank 8 is provided to avoid contact with the wheel 2.

A gap 9 is provided between the tip of the fin 6 and the side surface of the wheel 2, as shown in FIG. This gap 9 is 0.2 mm
The outer peripheral edge excluding the flank 8 is 1.1 mm.

In this embodiment, the disc material is made of SiC
Although a particle-dispersed aluminum alloy casting was used, other particle-dispersed aluminum alloy castings can also be employed.
Of course, cast iron or steel-based materials can also be used.

Examples and comparative examples will be described below.

[0021]

EXAMPLE A brake disk having a clearance 9 of 1.1 mm at the outer peripheral end except for the flank 8 shown in FIGS. 1 to 4 was prepared.

[0022]

[Comparative Example] The same size and material as those of the embodiment were used, and the gap was 1.
A brake disk (Comparative Example 1) having a size as large as 6 mm;
A conventional brake disk (Comparative Example 2) having the gap of 0.1 mm was prepared.

The brake disks of the above embodiment and comparative example were mounted on a brake tester having wheels mounted on a high-speed rotating shaft, and brake tests were performed at various rotational speeds. The friction coefficient on the disk sliding surface was calculated from the pad pressing force at the time of the test and the increase in the torque of the high-speed rotating shaft.

[0024]

[Table 1]

Table 1 shows the test results. The friction coefficient ratio in the table is based on Comparative Example 2. Comparative Example 2 of the conventional product shows a high friction coefficient, but the rotational speed is 230 km / h.
Then, cracks occurred in the fastening bolt holes.

It can be seen that the brake disk of the embodiment does not crack even at the maximum test speed of 355 km / h, and a high friction coefficient ratio of 90% or more with respect to the conventional product can be secured. On the other hand, in Comparative Example 1 where the gap is large, no crack is generated, but the decrease in the friction coefficient ratio in a high-speed region of 170 km / h or more is large, and is less than 90%.

[0027]

As described above, the brake disc for a railway vehicle according to the present invention has a structure in which 0.1 mm is provided between the tip of the fin and the side surface of the wheel.
With a 2-1.5mm gap, thermal expansion caused by excessive heat generation on the sliding surface is released in the thickness direction of the disk even in emergency use during high-speed running, and thermal stress in the circumferential direction is reduced. As a result, the occurrence of cracks and deformation can be prevented, and the escape of the sliding surface due to the pressing force of the pad can be minimized, and the coefficient of friction on the sliding surface can be maintained at a high value. In addition, due to the relaxation of the thermal stress, the disc can be formed of cast iron having low toughness or a cast of aluminum alloy dispersed with particles, and an integrated brake disc having excellent sliding characteristics on the sliding surface can be provided.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a state in which a brake disc according to an embodiment is mounted on wheels.

FIG. 2 is an exploded perspective view of FIG. 1 with a part omitted;

FIG. 3 is a rear view of the brake disc of FIG. 1;

FIG. 4 is an enlarged sectional view of a main part of FIG. 1;

FIG. 5 is an enlarged sectional view of a main part in a state where a conventional brake disc is mounted on wheels.

[Explanation of symbols]

 Reference Signs List 1 disc 2 wheel 3 bolt 4 sliding surface 5 pad 6 fin 7 hole 8 flank 9 gap 11 disk 12 wheel 13 bolt 14 sliding surface 15 fin 16 pad

Continued on the front page (72) Inventor Rikiya Inoue 1-12-19 Kitahorie, Nishi-ku, Osaka-shi F-term in Kurimoto Iron Works, Ltd. (reference) 3J058 AA53 AA62 AA87 BA37 CB12 CB14 CB23 CB25 DD02 DE02 DE05 EA05 EA08 FA21

Claims (3)

[Claims] 1. A brake disk for a railway vehicle, comprising a pair of disks mounted on both sides of a wheel side surface of a railway vehicle and having a sliding surface with a pad on a front surface side and radiating fins on a rear surface side. A brake disk for a railway vehicle, wherein a gap of 0.2 to 1.5 mm is provided between a tip of the fin and a wheel side surface. 2. The railway vehicle brake disk according to claim 1, wherein the gap is formed so as to increase toward the outer peripheral side of the disk. 3. The brake disk for a railway vehicle according to claim 1, wherein the disk is formed of cast iron or a particle-dispersed aluminum alloy casting.