Patent Application
20200124122
The present invention relates to a disk brake for use as a braking device for a railway vehicle. In particular, the present invention relates to a brake lining for a railway vehicle configured to be pressed against a sliding surface of a brake disk fastened to a wheel or an axle, and to a disk brake for a railway vehicle that is equipped with the brake lining.
In recent years, the use of disk brakes as braking devices for land transportation vehicles such as railway vehicles, automobiles and motorcycles is increasing as such vehicles become faster and larger. A disk brake is a device that produces a braking force by means of friction generated by sliding contact between a brake disk and a brake lining.
As a disk brake for a railway vehicle, a donut-shaped brake disk is mounted and fastened to a wheel or an axle, and a brake caliper presses a brake lining against a sliding surface of the brake disk, and thereby, a braking force is produced. In this manner, the rotation of the wheel or the axle is controlled, so that the running vehicle slows down.
In the case of a disk brake, a brake disk vibrates and a noise that is called “brake squeal” occurs during operation of the disk brake. It is considered that brake squeal occurs because the whole brake unit generates an unstable vibration called a “self-excited vibration”. Such a vibration arises due to friction when the brake lining is pressed against the brake disk for braking. The self-excited vibration is a vibration with an increasing amplitude that is generated as a result of external steady energy turning into vibration energy inside the system, and the vibration energy vibrating the system itself. In order to suppress brake squeal, it is necessary to suppress the self-excited vibration caused by the friction during the braking motion.
Patent Literature 1 discloses a disk brake wherein a pad is pressed against a brake disk via a piston. In the disk brake, the pad is moved toward a trailing side (contact ending side) that is the downstream side in the rotational direction of the brake disk by a friction when the pad is pressed against the brake disk. Accordingly, the contact area of the piston with the pad is greater on the trailing side than on the leading side that is the upstream side with respect to the rotational direction of the brake disk. Patent Literature 1 states that by this means, self-excited vibration is suppressed and thus brake squeal can be suppressed.
In Patent Literature 3, a brake lining is disclosed that has a similar structure to the brake lining disclosed in Patent Literature 2, and in which two friction members that are adjacent are connected by a plate-like member.
Patent Literature 1: Japanese Patent Application Publication No. 2002-340056
Patent Literature 2: Japanese Patent Application Publication No. 2011-214629
Patent Literature 3: Japanese Patent Application Publication No. 2012-251597
However, when the technique disclosed in Patent Literature 1 is to be applied to an existing vehicle, it is necessary to change not only the brake lining but also the brake caliper configured to apply a pressing force on the brake lining, and this affects the design of the whole disk brake. Therefore, it is extremely difficult to apply the technique to an existing vehicle.
In the structure of the brake lining disclosed in Patent Literature 2, the support stiffness of each of the elastic members needs to be adjusted in accordance with the position thereof on the back board, and therefore the manufacture management is complicated.
In the brake lining disclosed in Patent Literature 3, the purpose of connecting the two friction members together by the plate-like member is to suppress rotation of the respective friction members and suppressing variations in frictional coefficient between the individual friction members. Patent Literature 3 does not discuss suppression of brake squeal.
In view of the situation described above, an objective of the present invention is to provide a brake lining that can suppress brake squeal and which can be easily applied to an existing vehicle and for which manufacture management is simple, and to also provide a disk brake that includes such a brake lining.
A brake lining according to the present embodiment is a brake lining configured to be pressed against a sliding surface of a brake disk fastened to a wheel or an axle of a railway vehicle, the brake lining including:
a plurality of friction members arranged to be spaced from each other, each of the friction members having a front surface that is to face the sliding surface of the brake disk;
a back board fastened to a back surface of each of the friction members; and
a base plate supporting each of the friction members at a region including a center portion of each of the friction members, wherein a spring member is disposed between the base plate and the back boards on a back surface side of each of the friction members;
wherein:
two of the friction members that are adjacent to each other are taken as a pair, and the back board that is fastened to the pair of friction members is a one-piece member; and
a width of the back board at a space between the friction members of the pair of friction members is greater than a width of the friction member.
A disk brake according to the present embodiment is a disk brake including:
a brake disk fastened to a wheel or an axle of a railway vehicle; and
the aforementioned brake lining to be pressed against a sliding surface of the brake disk.
The brake lining and disk brake of the present invention can suppress brake squeal. It is easy to apply the brake lining and disk brake of the present invention to an existing vehicle, and the manufacture management of the brake lining and disk brake is simple.
Hereunder, an embodiment of a brake lining and a disk brake for a railway vehicle of the present invention will be described in detail.
As shown in
The brake lining 2 shown in
The friction members 3 are made of a copper sintered material or a resin material or the like. As shown in
The back boards 4 which are made of a thin plate of a metal such as steel are fastened to the back surface of each friction member 3 in order to maintain the strength and stiffness of the friction members 3. Two of the friction members 3 that are adjacent to each other are taken as a pair, and one back board 4 is provided for each pair of the friction members 3. The back board 4 is a one-piece member extending over both of the friction members 3. The pair of friction members 3 are in a state in which they are connected together by the back board 4. Therefore, the pair of friction members 3 are in a state in which they are connected together by the back board 4.
In this embodiment the back board 4 is an elliptical shape. In each pair of friction members 3, at a portion on an opposite side to a portion facing the other friction member 3, the back board 4 has substantially the same radius of curvature as the respective friction members 3, and an edge of the friction member 3 and an edge of the back board 4 substantially overlap. The arrangement direction of the pair of friction members 3 that are connected by the back board 4 is not particularly limited, and the pair of friction members 3 may be arranged in the radial direction of the brake disk 1, may be arranged in the circumferential direction, or may be arranged in a direction other than the radial direction and circumferential direction.
Each friction member 3 is fastened to the base plate 6, as well as the back board 4, by the rivet 7 that is inserted through the small hole 3a in the center portion of the individual friction members 3. That is, each friction member 3 is supported by the base plate 6 by means of the rivet 7 at a region that includes the center portion of the respective friction members 3. On a back surface side of each friction member 3, the spring member 5 is disposed between the back board 4 and the base plate 6. By this means, the plurality of friction members 3 are in a state in which each friction member 3 is elastically supported individually. Note that although disk springs are shown as an example of the spring members 5 in
According to the disk brake including the brake lining 2 having the configuration described above, each friction member 3 is individually movable. By this means, the contact surface pressure between the brake lining 2 and the brake disk 1 during braking motion can be uniformized.
Further, because each pair of friction members 3 is in a state in which the pair of friction members 3 are connected together by a one-piece back board 4, the movements thereof are constrained in comparison to a case where the friction members 3 are not connected together by a back board. Therefore, the frictional coefficient between the brake disk 1 and the brake lining 2 can be stabilized regardless of the running speed of the vehicle at the start of braking motion.
Furthermore, since each pair of friction members 3 is fastened to the base plate 6 by two rivets 7 as fastening members, a pair of friction members 3 does not rotate on the spot during braking motion, and thus looseness can be prevented from arising at portions at which the friction members 3 are fastened to the base plate 6. Even if the looseness arises at the fastening portions, the friction members 3 will not immediately fall off unless the fastening portions at the two locations are damaged at the same time. Therefore, sufficient durability and sufficient reliability of the disk brake can be ensured.
Since each of the friction members 3 is elastically supported with the position of the rivet 7 that is directly below the center portion thereof acting as a support point, the friction members 3 do not incline significantly even if the friction members 3 contact with the brake disk 1 and move during braking motion, and the entire contact surface of each friction member 3 becomes worn uniformly over the whole area thereof, and partial wearing of the friction members 3 does not occur.
In the brake lining 2 of the present invention, as shown in
By adopting a configuration so that 1<W/D, the bending stiffness of the back board 4 is increased, and it becomes difficult for the respective friction members 3 of the pair of friction members 3 to move independently. As a result, self-excited vibration of the brake lining is suppressed, and brake squeal decreases. To sufficiently exert this effect, preferably 1.1≤W/D, and more preferably 1.2≤W/D. Further, because the individual friction members 3 are supported at a region that includes the center portion of the friction member, self-excited vibration of the brake lining is suppressed and brake squeal decreases in comparison to, for example, a case where a pair of friction members is supported using a back board at only the middle portion of the pair of friction members.
In a case of applying this brake lining configuration to an existing vehicle, for example, it suffices to only change the back boards (back metals), and it is not necessary to change a brake caliper and the like. Further, in this brake lining there is no necessity to change the support stiffness of the spring members 5 depending on the positions thereof on the base plate 6. Accordingly, it is easy to apply the brake lining 2 to an existing vehicle, and the manufacture management of the brake lining 2 is simple.
If the connection portion width W of the back board 4 is too large in comparison to the width D of the friction member 3, the necessity will arise to increase the size of the base plate 6 in order to prevent interference between the back boards 4 to which the respective pairs of adjoining friction members 3 are attached. Therefore, the ratio of the connection portion width W of the back board 4 to the width D of the friction member 3 is preferably not more than 2 (1<W/D≤2), and more preferably is not more than 1.5 (1<W/D≤1.5).
Preferably the edge of the back board is smoothly continuous. Here the term “smoothly continuous” means that a tangential direction does not abruptly change. For example, if there is a portion which is not smoothly continuous, such as a notch, in the edge of the back board, the stiffness will decrease and stress will concentrate at the portion such as a notch, and for this reason it is not preferable for the edge to have a portion which is not smoothly continuous. The shape of the back board edge may be composed of only a curve, or may partially include a straight line shape.
Similarly to the back board 4 shown in
Squeal index values of brake linings were determined by a FEM (finite element method) analysis in a case where the width D of the friction member was made constant and the connection portion width W of the back board was changed. The term “squeal index value” refers to a value determined by, among damping values calculated by FEM complex eigenvalue analysis, summing up the damping values with negative values, that is, unstable oscillations, in each frequency range with a ⅓ octave band, obtaining the absolute value of the sum for the frequency range, and extracting the maximum value from the values for each frequency range. A smaller value of the squeal index means a smaller brake squeal sound.
Based on
Based on
The equal pressure performance (uniformity of pressure within butting faces of friction members with respect to a brake disk) was determined by FEM analysis for the respective brake linings illustrated in
The brake lining and disk brake for a railway vehicle of the present invention can be effectively utilized in various railway vehicles, and in particular is effectively utilized in high-speed railway vehicles which can run at various speeds in a wide range from low speed to high speed.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-255435 | Dec 2015 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2016/088092 | 12/21/2016 | WO | 00 |
