Disc brake system for railway vehicles

Abstract

This invention provides a disc brake device for railway vehicles that can suppress the warping of a brake disc. The disc brake device (1) includes a brake disc (2) and a brake bushing (4). The brake disc (2) is connected to a wheel by a plurality of bolts (6) inserted into a plurality of bolt holes (21). The brake bushing (4) includes a plurality of sliding member groups (41). Each sliding member group (41) includes an inner peripheral sliding member (42i) and an outer peripheral sliding member (42o). When the projected areas of the inner peripheral sliding member (42i) and the outer peripheral sliding member (42o) formed on the sliding surface (22) of the brake disc (2) are divided into an inner peripheral projection area (PAi) and an outer peripheral projection area (PAo) by a virtual circle (PC) passing through the center of each bolt hole (21), the area of ​​the outer peripheral projection area (PAo) is larger than the area of ​​the inner peripheral projection area (PAi).

Description

Disc brakes for railway vehicles The present invention relates to a disc brake device for railway vehicles. Disc brakes are widely used as braking systems for railway vehicles. They consist of a brake disc, brake caliper, and brake lining. The brake disc is mounted on the wheel and rotates with it. The brake lining is supported by the brake caliper. The movement of the brake caliper presses the brake lining against the brake disc. The friction between the brake lining and the brake disc brakes the disc and the wheel. Typically, a brake disc is connected to the wheel by a plurality of bolts. The brake disc has a ring shape, and the surface opposite to the "surface facing the wheel" serves as a sliding surface. In addition, the brake lining has a plurality of sliding members. The plurality of sliding members are mounted on the brake caliper through a mounting plate, facing the sliding surface of the brake disc. During braking (brake), the sliding members are pressed against the sliding surface of the brake disc. At this time, the temperature of the sliding surface rises due to the friction between the sliding members and the sliding surface. For this reason, the sliding surface of the brake disc undergoes thermal expansion, and in some cases, plastic deformation occurs. If such braking is repeated, warping will occur in the brake disc (for example, Japanese Patent Application Publication No. 2007-205428 (Patent Document 1)). Brake disc warping typically occurs when the outer circumference of the sliding surface is closer to the brake lining than the inner circumference. Excessive brake disc warping places excessive load on the bolts connecting the disc to the wheel. Furthermore, excessive brake disc warping causes the sliding surface to tilt significantly, leading to inconsistent contact between the sliding member and the sliding surface during braking. Therefore, there is a desire to suppress brake disc warping. [Prior Art] [Patent] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-205428 [Problem to be Solved by the Invention] The present invention was developed in view of the above-mentioned problem. The object of the present invention is to provide a disc brake device for railway vehicles that can suppress the warping of the brake disc. [Means for Solving the Problem] The railway vehicle disc brake device of the present invention comprises a brake disc, a brake caliper, and a brake lining. The brake disc has a circular ring shape and is provided with a plurality of bolt holes on the circumference around the center axis of the brake disc. The brake disc is connected to the wheel by a plurality of bolts inserted into the corresponding plurality of bolt holes. The brake lining is supported by the brake caliper. The brake lining comprises: a mounting plate and a plurality of sliding component groups. The mounting plate is mounted on the brake caliper. One side surface of the mounting plate faces the sliding surface of the brake disc. The plurality of sliding component groups are arranged in the circumferential direction of the brake disc on one of the above-mentioned side surfaces of the mounting plate. The plurality of sliding component groups respectively comprise: an inner peripheral sliding member, an outer peripheral sliding member, a back plate, an inner peripheral elastic member, an outer peripheral elastic member, an inner peripheral connecting member, and an outer peripheral connecting member. The inner peripheral sliding member and the outer peripheral sliding member are arranged in the radial direction of the brake disc. The inner sliding member and the outer sliding member each appear as a pentagon when viewed from above. The back plate is fixed to the surface of the mounting plate side of both the inner sliding member and the outer sliding member. The inner elastic member is arranged between the inner sliding member and the mounting plate. The outer elastic member is arranged between the outer sliding member and the mounting plate. The inner connecting member connects the inner sliding member to the mounting plate. The outer connecting member connects the outer sliding member to the mounting plate. In a disc brake device of this structure, when the projection area "formed on the sliding surface by projecting all the inner sliding members and outer sliding members of a plurality of sliding member groups onto the sliding surface along the central axis of the brake disc" is divided into an inner projection area and an outer projection area with "a virtual circle passing through the centers of a plurality of bolt holes" as a boundary, the area of ​​the outer projection area is larger than the area of ​​the inner projection area. [Effect of the Invention] According to the railway vehicle disc brake device of the present invention, warping of the brake disc can be suppressed. To achieve the above-mentioned objectives, the inventors of this application conducted intensive research and obtained the following insights. To suppress brake disc warping, the sliding surface temperature can be uniformly increased across the entire sliding surface during braking. This is because maintaining a uniform temperature rise across the entire sliding surface suppresses local thermal expansion. However, the temperature rise on the sliding surface is caused by the contact between the sliding component and the sliding surface. In reality, there are limitations to the configuration of sliding components. In this case, achieving a uniform temperature rise across the entire sliding surface and ensuring a uniform heat input from the sliding component to the sliding surface is difficult. In light of this, we used FEM analysis to examine the heat input distribution that minimizes warping in brake discs, considering the distribution of heat input on the sliding surface. The results are shown below. To connect the brake disc to the wheel via multiple bolts, the brake disc has multiple bolt holes. Each bolt hole is formed on a circumference around the central axis of the brake disc. Specifically, the center of each bolt hole is located on a virtual circle centered on the central axis of the brake disc. This virtual circle serves as a reference circle for the arrangement of the bolt holes and is also referred to as the pitch circle of the bolt holes in design. Hereinafter, this virtual circle for the arrangement of the bolt holes will sometimes be referred to as the pitch circle of the bolt holes. In a brake disc, when the sliding surface is divided into an outer circumference and an inner circumference, with the pitch circle of the bolt hole as the boundary, by making the heat input to the outer circumference greater than that to the inner circumference, warping can be suppressed to the same degree as with the same heat input, and excessive temperature rise can also be suppressed. To achieve this, the sliding member only needs to be positioned on the outer circumference of the brake disc's sliding surface, closer to the inner circumference. However, this heat input distribution and the placement of sliding components are determined by the contact conditions between the brake disc and the multiple sliding components. Specifically, to achieve this heat input distribution, the brake lining must have an isobaric structure, where each sliding component is in uniform contact with the brake disc. An isobaric brake lining has elastic components, such as springs, placed between each sliding component and the mounting plate. This elastic component ensures that the entire surface of each sliding component facing the brake disc is in uniform contact with the brake disc. In contrast, for example, in the case of a rigidly constructed brake lining in which "each sliding member is fixed to a mounting plate," no elastic member is arranged between each sliding member and the mounting plate. In this case, part of the sliding member does not come into contact with the brake disc, or only part of the sliding member comes into contact with the brake disc. This is based on the following reasons. The mounting plate is connected to the brake caliper in a part of the area, specifically in the central area of ​​the mounting plate. Therefore, the force applied to the mounting plate from the brake caliper strongly acts on the central area of ​​the mounting plate. Therefore, in a rigidly constructed brake lining, the part of the sliding member that overlaps with the "central area of ​​the mounting plate" is likely to come into contact with the brake disc. Another example of a brake lining with a structure similar to an "isostatic structure" is a structure in which multiple sliding members are connected using an elastically deformable plate, and the plate is fixed to a mounting plate. In this structure, although the compressive force (pressing force) is easily transmitted to the multiple sliding members through the plate, the compressive force (pressing force) is not evenly transmitted to all sliding members. The railway vehicle disc brake device of the present invention is an invention completed based on the above-mentioned insights. The following describes embodiments of the present invention. While examples are provided below to illustrate the embodiments of the present invention, the present invention is not limited to these examples. While specific numerical values ​​or materials are cited in the following description, the present invention is not limited to these. The railway vehicle disc brake device according to an embodiment of the present invention comprises a brake disc, a brake caliper, and a brake lining. The brake disc has a circular ring shape and is provided with a plurality of bolt holes on the circumference around the center axis of the brake disc. The brake disc is connected to the wheel by a plurality of bolts inserted into the corresponding plurality of bolt holes. The brake lining is supported by the brake caliper. The brake lining includes: a mounting plate and a plurality of sliding member groups. The mounting plate is mounted on the brake caliper. One side surface of the mounting plate faces the sliding surface of the brake disc. The plurality of sliding member groups are arranged in the circumferential direction of the brake disc on one of the above-mentioned side surfaces of the mounting plate. The plurality of sliding member groups respectively include: an inner peripheral sliding member, an outer peripheral sliding member, a back plate, an inner peripheral elastic member, an outer peripheral elastic member, an inner peripheral connecting member, and an outer peripheral connecting member. The inner peripheral sliding member and the outer peripheral sliding member are arranged in the radial direction of the brake disc. The inner sliding member and the outer sliding member each appear as a pentagon when viewed from above. The back plate is fixed to the surface of the mounting plate side of both the inner sliding member and the outer sliding member. The inner elastic member is disposed between the inner sliding member and the mounting plate. The outer elastic member is disposed between the outer sliding member and the mounting plate. The inner connecting member connects the inner sliding member to the mounting plate. The outer connecting member connects the outer sliding member to the mounting plate. In a disc brake device of this structure, when the projected area on the sliding surface formed by "projecting all the inner sliding members and outer sliding members of the plurality of sliding member groups onto the sliding surface along the central axis of the brake disc" is divided into an inner projection area and an outer projection area with a virtual circle passing through the centers of the plurality of bolt holes as a boundary, the area of ​​the outer projection area is larger than the area of ​​the inner projection area (first structure). In the disc brake device of the first structure, the brake lining includes multiple sliding member assemblies. In each sliding member assembly, an inner elastic member is positioned between the inner sliding member and the mounting plate, and the inner sliding member is connected to the mounting plate via an inner connecting member. Additionally, an outer elastic member is positioned between the outer sliding member and the mounting plate, and the outer sliding member is connected to the mounting plate via an outer connecting member. In this configuration, the brake lining has an isobaric structure. Therefore, the entire surface of each sliding member on the brake disc side contacts the sliding surface of the brake disc evenly. Furthermore, in the disc brake device of the first structure, when the projected area of ​​the inner and outer sliding members formed on the sliding surface of the brake disc is divided into an inner projected area and an outer projected area using a virtual circle passing through the centers of the multiple bolt holes (the pitch circle of the bolt holes) as the boundary, the outer projected area is larger than the inner projected area. Specifically, all inner and outer sliding members of the plurality of sliding member assemblies are positioned as a whole so as to be close to the outer circumference of the brake disc's sliding surface. This allows the outer and inner circumferences of the brake disc to be divided into a larger heat input compared to the inner circumference, using the pitch circle of the bolt holes as the boundary. Therefore, the railway vehicle disc brake device of the first structure can suppress brake disc warping to the same degree as under the same heat input, while also preventing excessive temperature increases in the brake disc. In the disc brake device of the first structure, the ratio of the area of ​​the outer peripheral side projected region to the area of ​​the inner peripheral side projected region is preferably 1.10 or greater (second structure). In this case, warping of the brake disc can be more effectively suppressed. In the disc brake device of the first or second configuration, when braking, the heat input applied to the sliding surface of the brake disc by the sliding of the inner and outer sliding members with the sliding surface is divided into inner and outer heat inputs with the aforementioned imaginary circle as the boundary. The ratio of the outer heat input to the inner heat input is preferably 1.10 or greater (third configuration). In this case, the heat input to the outer region is greater than the heat input to the inner region. Therefore, warping of the brake disc can be more effectively suppressed. Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The same or corresponding structures in the various drawings are denoted by the same reference numerals, and their descriptions will not be repeated. [Disc Brake System] FIG1 is a top view of a disc brake system 1 according to this embodiment. Disc brake system 1 is used as a braking system for railway vehicles. Referring to FIG1 , disc brake system 1 includes a brake disc 2 , a brake lining 3 , and a brake caliper 4 . [Structure of the brake disc] First, the structure of the brake disc 2 is described. As shown in Figure 1, the brake disc 2 has a ring shape. The brake disc 2 is connected to the wheel 5 by a plurality of bolts 6. In order to connect the bolts 6, the brake disc 2 has a plurality of bolt holes 21. The bolt holes 21 are arranged at intervals along the circumferential direction of the brake disc 2. Specifically, the bolt holes 21 are formed on the circumference around the central axis of the brake disc 2. That is, the center of each bolt hole 21 is arranged on a virtual circle PC with the central axis of the brake disc 2 as the center. In other words, the virtual circle PC passes through the center of each bolt hole 21. This virtual circle PC is the pitch circle of the bolt hole 21. Hereinafter, this virtual circle PC is sometimes referred to as the pitch circle of the bolt hole 21. Bolts 6 are inserted into bolt holes 21 to connect the brake disc 2 to the wheel 5. The brake disc 2 is substantially coaxial with the wheel 5. The brake disc 2 is disposed on both sides of the wheel 5. Fig. 2 is a cross-sectional view taken along line II-II of the disc brake device 1 shown in Fig. 1. In Fig. 2, only one of the brake discs 2 mounted on both sides of the wheel 5 is shown, and the other is omitted. Referring to Figure 2 , the brake disc 2 has a front surface 22 and a back surface 23. The front surface 22 faces outward in the thickness direction of the brake disc 2. The front surface 22 is a sliding surface to which a brake lining (not shown) is pressed. Hereinafter, the front surface 22 of the brake disc 2 will sometimes be referred to as the sliding surface 22. The back surface 23 is the side facing the wheel 5. If the brake disc 2 has multiple longitudinal fins extending in the radial direction, the back surface 23 is the top surface of the longitudinal fins. Each bolt hole 21 extends through the brake disc 2. Each bolt hole 21 includes a large-diameter portion 211 and a small-diameter portion 212. The large-diameter portion 211 is larger than the small-diameter portion 212. The large-diameter portion 211 and the small-diameter portion 212 are arranged in this order from the front (sliding surface) 22 toward the back 23 of the brake disc 2. The wheel 5 has a plurality of through-holes 51. These through-holes 51 correspond to the bolt holes 21 of the brake disc 2 and are formed in the wheel 5. The brake disc 2 is mounted on both sides of the wheel 5. Therefore, the bolt holes 21 of one brake disc 2, the through-holes 51 of the wheel 5, and the bolt holes of the other brake disc (not shown) are arranged in sequence. Insert the bolt 6 into: the bolt hole 21 of one of the brake discs 2, the through hole 51 of the wheel 5, and the bolt hole of the other brake disc. Place the head 61 of the bolt 6 in the large diameter portion 211 of the bolt hole 21 of one of the brake discs 2, and place the nut (not shown) in the large diameter portion of the bolt hole of the other brake disc. The brake disc 2 is connected to the wheel 5 by engaging the threaded portion of the bolt 6 with the threaded portion of the nut. In the example shown in Figure 2, an elastic member 7 is arranged between the head 61 of the bolt 6 and the small diameter portion 212 of the large diameter portion 211 of the bolt hole 21 of one of the brake discs 2. The elastic member 7 is, for example, made of stacked disc springs. Similarly, an elastic member is also arranged between the nut and the small diameter portion of the large diameter portion of the bolt hole of the other brake disc. [Structure of the brake lining] Returning to Figure 1, the structure of the brake lining 4 will be described. As shown in Figure 1, the brake lining 4 includes a mounting plate 40 and a plurality of sliding member groups 41. The brake lining 4 is supported by the brake caliper 3. Specifically, the mounting plate 40 has a roughly rectangular shape when viewed from the front. The mounting plate 40 is configured to overlap a portion of the brake disc 2 in the circumferential direction. The mounting plate 40 is mounted on the brake caliper 3. The mounting plate 40 is connected to the brake caliper 3 in the central area of ​​the mounting plate 40. A plurality of sliding member groups 41 are arranged at intervals in the circumferential direction of the brake disc 2. The plurality of sliding member groups 41 do not have to be arranged completely along the circumferential direction of the brake disc 2, as long as they are substantially arranged in the circumferential direction of the brake disc 2. In this embodiment, six sliding member groups 41 are arranged in the circumferential direction of the brake disc 2. Each sliding member group 41 includes an inner circumferential side sliding member 42i and an outer circumferential side sliding member 42o as sliding members. The inner circumferential side sliding member 42i is arranged on the inner circumferential side of the brake disc 2. The outer circumferential side sliding member 42o is arranged on the outer circumferential side of the brake disc 2. The inner circumferential side sliding member 42i and the outer circumferential side sliding member 42o are arranged at intervals in the radial direction of the brake disc 2. The inner sliding member 42i and the outer sliding member 42o are each plate-shaped and appear pentagonal when viewed from above. One of the five edges of the inner sliding member 42i is adjacent to the outer sliding member 42o, and this edge extends circumferentially around the brake disc 2. One of the five edges of the outer sliding member 42o is adjacent to the inner sliding member 42i, and this edge extends circumferentially around the brake disc 2. One of the five vertices of the inner sliding member 42i is located on the opposite side of the outer sliding member 42o, and the corner containing this vertex protrudes radially inward of the brake disc 2. One of the five vertices of the outer sliding member 42o is located on the opposite side of the inner sliding member 42i, and the corner containing this vertex protrudes radially outward of the brake disc 2. The shape of the inner circumferential sliding member 42i and the outer circumferential sliding member 42o when viewed from above can be essentially a pentagon. Specifically, the five edges of the inner circumferential sliding member 42i and the outer circumferential sliding member 42o can be straight or curved. For example, of the five edges of the inner circumferential sliding member 42i, the two edges extending in the radial direction of the brake disc 2 can also be curved to form an expanded shape. Of the five edges of the outer circumferential sliding member 42o, the two edges extending in the radial direction of the brake disc 2 can also be curved to form an expanded shape. In the example shown in Figure 1, the outer circumferential sliding member 42o of each of the four sliding member groups 41 arranged on the central side and the inner circumferential sliding member 42i of each of the two sliding member groups 41 arranged at the two ends have two curved edges. In addition, the corners of the inner circumferential sliding member 42i, each containing five vertices, can also be rounded. In the outer sliding member 42o, each of the corners having five vertices may be rounded. The shape of the inner sliding member 42i and the outer sliding member 42o in a plan view may be, for example, round or a polygon such as a square or hexagon. Each sliding member group 41 includes an inner circumferential sliding member 42i and an outer circumferential sliding member 42o, and is mounted on one side of the mounting plate 40. The side faces the sliding surface 22 of the brake disc 2. In addition, the number of sliding member groups 41 is not particularly limited as long as it is plural. In the sliding member group 41, the size (dimensions) of the outer circumferential sliding member 42o in a top view may be the same as or different from the inner circumferential sliding member 42i. In addition, among the sliding member groups 41, the size (dimensions) of the inner circumferential sliding member 42i in a top view may be the same as or different from each other, and the size (dimensions) of the outer circumferential sliding member 42o in a top view may be the same as or different from each other. In the example shown in FIG1 , the outer sliding members 42 o of each of the four sliding member groups 41 arranged in the center and the inner sliding members 42 i of each of the two sliding member groups 41 arranged at the ends are of the same size (dimensions), while the inner sliding members 42 i of each of the four sliding member groups 41 arranged in the center and the outer sliding members 42 o of each of the two sliding member groups 41 arranged at the ends are of the same size (dimensions). For example, in the four sliding member groups 41 arranged in the center, the outer sliding members 42 o are larger than the inner sliding members 42 i. The brake lining 4 of this embodiment has an isobaric structure. Hereinafter, the brake lining 4 having an isobaric structure will be described with reference to FIG. 3 . Figure 3 is a cross-sectional view taken along line III-III of the disc brake device 1 shown in Figure 1. As shown in Figure 3, the sliding member assembly 41 constituting the brake lining 4 includes, in addition to the inner sliding member 42i and the outer sliding member 42o, a back plate 43, an inner elastic member 44i, an outer elastic member 44o, an inner connecting member 45i, and an outer connecting member 45o. The back plate 43 is fixed to the surface (back surface) of both the inner circumference side sliding member 42i and the outer circumference side sliding member 42o on the mounting plate 40 side. Specifically, a set of the inner circumference side sliding member 42i and the outer circumference side sliding member 42o are connected by a single back plate 43. The inner circumferential elastic member 44i is disposed between the inner circumferential sliding member 42i and the mounting plate 40. Specifically, the inner circumferential elastic member 44i is disposed between the mounting plate 40 and the back plate 43 fixed to the inner circumferential sliding member 42i behind the corresponding inner circumferential sliding member 42i. The outer circumferential elastic member 44o is disposed between the outer circumferential sliding member 42o and the mounting plate 40. Specifically, the outer circumferential elastic member 44o is disposed between the mounting plate 40 and the back plate 43 fixed to the outer circumferential sliding member 42o behind the corresponding outer circumferential sliding member 42o. The inner circumferential elastic member 44i and the outer circumferential elastic member 44o are, for example, disc springs. However, the inner circumferential elastic member 44i and the outer circumferential elastic member 44o may alternatively be leaf springs or coil springs. The inner connecting member 45i connects the inner sliding member 42i to the mounting plate 40. Specifically, the inner connecting member 45i is located at the center of gravity of the corresponding inner sliding member 42i. The outer connecting member 45o connects the outer sliding member 42o to the mounting plate 40. Specifically, the outer connecting member 45o is located at the center of gravity of the corresponding outer sliding member 42o. The inner connecting member 45i and the outer connecting member 45o are, for example, rivets. The inner sliding member 42i, the back plate 43, and the inner elastic member 44i are mounted to the mounting plate 40 via the inner connecting member 45i. The outer sliding member 42o, the back plate 43, and the outer elastic member 44o are mounted to the mounting plate 40 via the outer connecting member 45o. Thus, the brake lining 4 includes a plurality of sliding member assemblies 41. In each sliding member assembly 41, an inner elastic member 44i is disposed between the inner sliding member 42i and the mounting plate 40. The inner sliding member 42i is connected to the mounting plate 40 via an inner connecting member 45i. Additionally, an outer elastic member 44o is disposed between the outer sliding member 42o and the mounting plate 40. The outer sliding member 42o is connected to the mounting plate 40 via an outer connecting member 45o. In this embodiment, the brake lining 4 has an isobaric structure. Therefore, during braking, as long as the brake caliper is actuated to move the brake lining 4 toward the brake disc 2, the entire surfaces of the inner and outer sliding members 42i, 42o on the brake disc 2 side uniformly contact the sliding surface 22 of the brake disc 2. [Configuration of sliding members] FIG4 is a schematic diagram showing the configuration relationship of the inner circumferential sliding member 42i and the outer circumferential sliding member 42o relative to the brake disc 2 in the disc brake device 1 of the present embodiment. FIG4 shows a top view of the brake disc 2. As shown in FIG4, in the brake disc 2, the sliding surface 22 is divided into an outer circumferential area 22o and an inner circumferential area 22i with the pitch circle PC of the bolt hole 21 as the boundary. In addition, all the inner circumferential sliding members 42i and the outer circumferential sliding members 42o of the plurality of sliding member groups 41 are projected onto the sliding surface 22 along the central axis of the brake disc 2, and a projection area PA of the inner circumferential sliding member 42i and the outer circumferential sliding member 42o is formed on the sliding surface 22. Then, with the pitch circle PC of the bolt hole 21 as the boundary, the projection area PA is divided into an inner circumferential projection area PAi and an outer circumferential projection area PAo. In the disc brake device 1 of this embodiment, all inner sliding members 42i and outer sliding members 42o of the plurality of sliding member groups 41 are arranged so that the area of ​​the outer projected area PAo is larger than the area of ​​the inner projected area PAi. Specifically, all inner sliding members 42i and outer sliding members 42o of the plurality of sliding member groups 41 are positioned so as to be closer to the outer periphery of the sliding surface 22 of the brake disc 2. In this case, when braking is performed, the inner and outer sliding members 42i, 42o slide against the sliding surface 22. Once heat is input to the sliding surface 22 from the inner and outer sliding members 42i, 42o experience greater heat input to the outer area 22o than to the inner area 22i. [Effect] In the disc brake device 1 of this embodiment, the brake lining 4 is an isobaric structure. Therefore, the entire surface of the inner circumferential sliding member 42i and the outer circumferential sliding member 42o on the brake disc 2 side is in uniform contact with the sliding surface 22 of the brake disc 2. In addition, all the inner circumferential sliding members 42i and the outer circumferential sliding members 42o of the plurality of sliding member groups 41 are arranged as a whole so as to be close to the outer circumferential side of the sliding surface 22 of the brake disc 2. For this reason, the heat input amount to the outer circumferential area 22o of the brake disc 2 can be increased compared to the heat input amount to the inner circumferential area 22i. Therefore, as described above, the warping of the brake disc 2 can be suppressed to the same degree as "when the heat input amount is the same", and the excessive temperature rise of the brake disc 2 can be suppressed. In the disc brake device 1 of this embodiment, a plurality of sliding member assemblies 41 are arranged circumferentially around the brake disc 2. Each sliding member assembly 41 includes an inner sliding member 42i and an outer sliding member 42o arranged radially relative to the brake disc 2. Therefore, the inner sliding members 42i and outer sliding members 42o are appropriately sized to effectively absorb the elastic forces from the inner and outer elastic members 44i and 44o. Furthermore, since the inner and outer sliding members 42i and 42o are connected by a back plate 43, they are prevented from falling or spinning. In this embodiment, the inner sliding member 42i and outer sliding member 42o in each sliding member assembly 41 each have a pentagonal shape when viewed from above. This allows the inner sliding members 42i and outer sliding members 42o to be closely spaced. Consequently, the contact area between the inner sliding members 42i and outer sliding members 42o and the sliding surface 22 of the brake disc 2 is sufficiently ensured. [Ideal State] For the brake lining 4, a plurality of inner sliding members 42i and outer sliding members 42o are arranged so that the ratio of the area of ​​the outer projection area PAo to the area of ​​the inner projection area PAi is greater than 1.10. As long as the ratio of the area of ​​the outer projection area PAo to the area of ​​the inner projection area PAi is greater than 1.10, the warping of the brake disc 2 can be more effectively suppressed. The area ratio is preferably greater than 1.20, and more preferably greater than 1.25. There is no particular upper limit to the area ratio. However, if the area ratio is too large, the temperature of the brake disc will rise locally, resulting in uneven wear. Therefore, the area ratio is preferably less than 1.80. For the brake disc 2, when braking, the heat input applied to the sliding surface 22 of the brake disc 2 by the sliding movement of the inner and outer sliding members 42i, 42o against the sliding surface 22 is preferably divided into inner and outer heat inputs, using the pitch circle PC of the bolt hole 21 as the boundary. The ratio of the outer heat input to the inner heat input is preferably 1.10 or greater. In other words, the ratio of the heat input of the outer projected area 22o to the heat input of the inner projected area 22i is preferably 1.10 or greater. When the ratio of the heat input of the outer projected area 22o to the inner projected area 22i is 1.10 or greater, the heat input to the outer area 22o is greater than the heat input to the inner area 22i. Consequently, warping of the brake disc 2 can be more effectively suppressed. This heat input ratio is preferably 1.20 or greater, and more preferably 1.25 or greater. There is no particular upper limit to this heat input ratio. However, if the heat input ratio is too large, the temperature of the brake disc will rise locally, causing partial wear. Therefore, the heat input ratio is preferably below 1.80. [Example] Next, in order to confirm the effect of the disc brake device 1 of this embodiment, FEM analysis was performed. FIG5 is a cross-sectional view of the analysis model of the brake disc 2 used in the FEM analysis of the embodiment. The analysis model shown in FIG5 is a model that simulates the disc brake device 1 shown in FIG1 , and the cross section shown in FIG5 is equivalent to the cross section shown in FIG2 . The analysis model is composed of a brake disc 2, a bolt 6, an elastic member 7, and a wheel 5. Taking into account the axial symmetry, a model of "forming 1 / 2 in the axial direction of the wheel having the brake disc and forming 1 / 12 in the circumferential direction of the brake disc" is adopted as the analysis model. The brake disc 2 is constructed of an elastic-plastic solid to replicate thermal deformation. Other components (bolts 6, elastic member 7, and wheel 5) are constructed of either an elastic or an elastic-plastic solid. Each component uses a hexahedron primary element as its element type. The minimum element size for the brake disc 2 and other components is 0.5 mm. The minimum element size for other components may be larger. Assume that the analysis model is subjected to three braking energies equivalent to a specific braking condition. The braking condition is an emergency stop from a speed of 360 km / h. The initial axial force of bolt 6 is determined based on the actual brake disc 2. Next, in the analysis model of the brake disc 2, a heat input distribution Q is assigned to the entire area of ​​the sliding surface 22. The heat input distribution Q adopts 7 conditions. However, the total amount of heat input is the same in the 7 conditions. Figures 6, 7, 8, 9, and 10 show the patterns of the heat input distribution Q under the 7 conditions. Figure 6 is a schematic diagram showing the heat input distribution Q of Inventive Examples 1 to 3. Figure 7 is a schematic diagram showing the heat input distribution Q of Comparative Example 1. Figure 8 is a schematic diagram showing the heat input distribution Q of Comparative Example 2. Figure 9 is a schematic diagram showing the heat input distribution Q of Comparative Example 3. Figure 10 is a schematic diagram showing the heat input distribution Q of Comparative Example 4. Referring to Figure 6, in Inventive Examples 1-3, the heat input to the outer peripheral area 22o is greater than that to the inner peripheral area 22i. In this case, the area of ​​the outer peripheral projected area PAo is larger than that of the inner peripheral projected area PAi. Referring to Figure 7, in Comparative Example 1, the heat input is the same. Referring to Figures 8 and 9, in Comparative Examples 2 and 3, the heat input to the outer peripheral area 22o is the same as that to the inner peripheral area 22i. However, as shown in Figure 8, in Comparative Example 2, the heat input at the pitch circle PC of the bolt hole 21 is reduced, resulting in an overall W-shaped heat input. As shown in Figure 9, in Comparative Example 3, the heat input at the pitch circle PC of the bolt hole 21 is increased, resulting in an overall V-shaped heat input. In Comparative Examples 1-3, the area of ​​the outer peripheral projected area PAo is the same as that of the inner peripheral projected area PAi. Referring to Figure 10, in Comparative Example 4, the heat input to the outer peripheral area 22o is smaller than that to the inner peripheral area 22i. In this case, the area of ​​the outer peripheral side projection area PAo is smaller than the area of ​​the inner peripheral side projection area PAi. More specifically, in Inventive Examples 1 to 3, the heat input ratio of the outer peripheral area 22o to the inner peripheral area 22i is greater than 1.00. The heat input ratio of Inventive Example 1 is 1.70. In this case, the area ratio of the outer peripheral projected area PAo to the inner peripheral projected area PAi is 1.70. The heat input ratio of Inventive Example 2 is 1.40. In this case, the area ratio is 1.40. The heat input ratio of Inventive Example 3 is 1.20. In this case, the area ratio is 1.20. In Comparative Examples 1 to 3, the heat input ratio of the outer peripheral area 22o to the inner peripheral area 22i is 1.00. In this case, the area ratio of the outer peripheral projected area PAo to the inner peripheral projected area PAi is 1.00. In Comparative Example 4, the heat input ratio of the outer peripheral area 22o to the inner peripheral area 22i is less than 1.00. The heat input ratio of Comparative Example 4 is 0.60. In this case, the area ratio of the outer peripheral side projection area PAo to the inner peripheral side projection area PAi is 0.60. Figure 11 is a cross-sectional view of the analysis model of a brake disc 2 that warps due to heat input. In the FEM analysis, the amount of warpage d generated in the brake disc 2 is evaluated. The warpage d is the displacement in the thickness direction of the outer periphery of the sliding surface 22. Using "Comparative Example 1 with the same heat input" as a benchmark, as long as the warpage is equal to that of Comparative Example 1 or is within 15% of the warpage of Comparative Example 1, it is judged as good (OK). In addition, the "maximum temperature within 6 mm from the sliding surface 22" is evaluated. As long as the maximum temperature does not exceed the 700°C limit set by the brake disc 2, it is judged as good (OK). The analysis results are shown in Table 1. The results in Table 1 reveal the following. As in Inventive Examples 1-3, when the heat input to the outer circumferential region 22o is greater than that to the inner circumferential region 22i, warpage is suppressed, and excessive temperature rise of the brake disc 2 is prevented. As in Comparative Example 2, when the heat input to the outer circumferential region 22o is the same as that to the inner circumferential region 22i, and when the heat input to the pitch circle PC of the bolt hole 21 is reduced, no suppression of warpage is observed. As in Comparative Example 3, even when the heat input to the outer circumferential region 22o is the same as that to the inner circumferential region 22i, warpage is suppressed when the heat input to the pitch circle PC of the bolt hole 21 is increased. However, in Comparative Example 3, excessive temperature rise of the brake disc 2 is observed. As in Comparative Example 4, when the heat input to the outer circumferential region 22o is less than that to the inner circumferential region 22i, no suppression of warpage is observed. The above results confirm the effectiveness of the disc brake device 1 of this embodiment. The above describes the embodiment of the present invention. However, the above embodiment is merely an example for implementing the present invention. Therefore, the present invention is not limited to the above embodiment, and the above embodiment can be appropriately modified and implemented without departing from the scope of the present invention. 1: Disc brake 2: Brake disc 3: Brake caliper 4: Brake lining 5: Wheel 6: Bolt 21: Bolt hole PC: Virtual circle (pitch circle) 22: Surface (sliding surface) 22i: Inner area 22o: Outer area 40: Mounting plate 41: Sliding member assembly 42i: Inner sliding member 42o: Outer sliding member PA: Projected area PAi: Inner projected area PAo: Outer projected area 43: Back plate 44i: Inner elastic member 44o: Outer elastic member 45i: Inner connecting member 45o: Outer connecting member [Figure 1] Figure 1 is a top view of the disc brake device of the present embodiment. [Figure 2] Figure 2 is a cross-sectional view of the disc brake device shown in Figure 1 taken along the line II-II. [Figure 3] Figure 3 is a cross-sectional view of the disc brake device shown in Figure 1 taken along the line III-III. [Figure 4] Figure 4 is a schematic diagram showing the arrangement relationship of the inner circumferential sliding member and the outer circumferential sliding member relative to the brake disc in the disc brake device of the present embodiment. [Figure 5] Figure 5 is a cross-sectional view of the analysis model of the brake disc used in the FEM analysis of the embodiment. [Figure 6] Figure 6 is a schematic diagram showing the heat input distribution of Inventive Examples 1 to 3. [Figure 7] Figure 7 is a schematic diagram showing the heat input distribution of Comparative Example 1. [Figure 8] Figure 8 is a schematic diagram showing the heat input distribution of Comparative Example 2. [Figure 9] Figure 9 is a schematic diagram showing the heat input distribution of Comparative Example 3. [Figure 10] Figure 10 is a schematic diagram showing the heat input distribution of Comparative Example 4. [Figure 11] Figure 11 is a cross-sectional view of an analytical model of a brake disc warping due to heat input. 1: Disc brake device 2: Brake disc 6: Bolts 21: Bolt hole 22: Surface (sliding surface) 22i: Inner circumference area 22o: Peripheral area PA: Projection Field PAi: Inner projection area PAo: Peripheral Projection Area PC: Virtual circle (pitch circle)

Claims

1. A disc brake device for railway vehicles, comprising: a brake disc having an annular shape and having a plurality of bolt holes formed on the circumference around the central axis of the brake disc, for connection to a wheel by inserting a plurality of bolts into the corresponding plurality of bolt holes; a brake caliper; a brake pad supported by the brake caliper and mounted on the brake caliper, comprising a mounting plate and a plurality of sliding member assemblies, wherein one side of the mounting plate faces the sliding surface of the brake disc, the plurality of sliding member assemblies are arranged in the circumferential direction of the brake disc on the aforementioned side of the mounting plate, and the plurality of sliding member assemblies each include: an inner peripheral sliding member and an outer peripheral sliding member arranged radially on the brake disc and respectively appearing pentagonal in a top view; and a back plate fixed to the surfaces of the inner peripheral sliding member and the outer peripheral sliding member on the mounting plate side. An inner peripheral elastic member is disposed between the aforementioned inner peripheral sliding member and the aforementioned mounting plate; an outer peripheral elastic member is disposed between the aforementioned outer peripheral sliding member and the aforementioned mounting plate; an inner peripheral connecting member connects the aforementioned inner peripheral sliding member to the aforementioned mounting plate; an outer peripheral connecting member connects the aforementioned outer peripheral sliding member to the aforementioned mounting plate. When the projected area of ​​all the aforementioned inner peripheral sliding members and the aforementioned outer peripheral sliding members of the aforementioned plurality of sliding member groups is projected onto the aforementioned sliding surface along the central axis of the aforementioned brake disc, and the projected area on the aforementioned sliding surface is divided into an inner peripheral projection area and an outer peripheral projection area by using the virtual circle passing through the center of each of the aforementioned plurality of bolt holes as the boundary, the area of ​​the aforementioned outer peripheral projection area is larger than the area of ​​the aforementioned inner peripheral projection area.

2. The disc brake device as described in claim 1, wherein the ratio of the area of ​​the aforementioned outer peripheral projection field to the area of ​​the aforementioned inner peripheral projection field is 1.10 or more.

3. The disc brake device as described in claim 1 or claim 2, wherein when braking, the heat input applied to the aforementioned sliding surface by the sliding of the aforementioned inner peripheral sliding member and the aforementioned outer peripheral sliding member with the aforementioned brake disc, when the heat input is divided into inner peripheral heat input and outer peripheral heat input by the aforementioned virtual circle as a boundary, the ratio of the aforementioned outer peripheral heat input to the aforementioned inner peripheral heat input is 1.10 or more.

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