Disc brake device

Abstract

To obtain a disc brake device capable of improving rust resistance and wear resistance as a whole.SOLUTION: A disc brake device comprises, as an example, a disc configured to be held between two brake pads when braking a vehicle, a hat connecting the disc to an axle of the vehicle, and metal coatings that is formed by electroless plating and electrolytic plating, where the metal coatings include a first coating that is provided on two surfaces of the disc facing the brake pads, and a second coating that is less prone to rust than the hat, is provided on the surface of the hat, and differs from the first coating in at least one of a material and a manufacturing method.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] An embodiment of the present invention relates to a disc brake device. [Background technology]

[0002] Conventionally, a disc brake device is known that applies brakes to a vehicle by clamping a disc rotor with brake pads. The disc rotor has, for example, a disc clamped between the brake pads and a hat connected to an axle. A coating may be applied to the surface of the disc, for example, to improve rust resistance (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2021-510409 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional configuration, the coating improves the rust resistance of the disk of the disk rotor, and there is still room for improvement in the rust resistance and wear resistance of the disk brake device as a whole.

[0005] Therefore, the present invention has been made in consideration of the above, and provides a disc brake device that can improve the rust resistance and wear resistance as a whole. [Means for solving the problem]

[0006] A disc brake device according to an embodiment of the present invention includes, as an example, a disc configured to be sandwiched between two brake pads when braking a vehicle, a hat connecting the disc to an axle of the vehicle, a first coating formed by electroless plating and electrolytic plating on two side surfaces of the disc facing the brake pads, and a second coating that is less susceptible to rust than the hat, is provided on the surface of the hat, and is different from the first coating in at least one of material and manufacturing method. Thus, as an example, the first coating improves the rust resistance and wear resistance of the side surfaces of the disc. Furthermore, the second coating improves the rust resistance of the surface of the hat. Thus, the disc brake device can improve the rust resistance and wear resistance as a whole. [Brief description of the drawings]

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

[0008] An embodiment will be described below with reference to FIGS. 1 to 5. In this specification, components according to the embodiment and their descriptions may be described in a number of ways. The components and their descriptions are merely examples and are not limited by the expressions in this specification. The components may be identified by names different from those in this specification. The components may also be described by expressions different from those in this specification.

[0009] In the following description, "suppress" is defined as, for example, preventing the occurrence of an event, action, or influence, or reducing the severity of an event, action, or influence. Also, in the following description, "restrict" is defined as, for example, preventing movement or rotation, or allowing movement or rotation within a predetermined range and preventing movement or rotation beyond the predetermined range.

[0010] Fig. 1 is a cross-sectional view showing a disc brake device 10 according to this embodiment. As shown in Fig. 1, the disc brake device 10 is mounted on a vehicle 1 such as a four-wheeled automobile. However, the disc brake device 10 is not limited to this example.

[0011] The disc brake device 10 includes a disc rotor 11 and two brake pads 12. The disc brake device 10 further includes, for example, a caliper that supports the two brake pads 12 and various other components.

[0012] Fig. 2 is a cross-sectional view showing the disk rotor 11 of this embodiment. Fig. 3 is a cross-sectional view showing the disk rotor 11 of this embodiment along the line F3-F3 in Fig. 2. As shown in Fig. 2, the disk rotor 11 is formed in a hat shape as a whole.

[0013] The disc rotor 11 is made of a metal such as cast iron. However, the material of the disc rotor 11 is not limited to this example. The disc rotor 11 has a hat 21 and a disc 22. The disc 22 may also be referred to as a sliding portion, for example. In this embodiment, the disc rotor 11 is a single component in which the hat 21 and the disc 22 are integrally formed. However, for example, the hat 21 and the disc 22 may be independent of each other and connected to each other by a fastener.

[0014] 1, the hat 21 is connected to an axle 30 of the vehicle 1. The axle 30 has, for example, a hub 31 and a drive shaft 32. However, the axle 30 is not limited to this example. The drive shaft 32 may also be referred to as an axle shaft.

[0015] The hub 31 is attached to, for example, a knuckle 35 of a suspension via a ball bearing 36. The hub 31 is supported by the knuckle 35 so as to be rotatable about a central axis Ax. The disc rotor 11 rotates integrally with the hub 31 about the central axis Ax.

[0016] The central axis Ax is an imaginary central axis of rotation of the hub 31, and extends substantially in the vehicle width direction of the vehicle 1. During turning, the direction in which the central axis Ax of the front wheel extends is inclined obliquely with respect to the vehicle width direction.

[0017] In this specification, the axial direction, radial direction, and circumferential direction are defined. The axial direction is a direction along the central axis Ax, and includes a first axial direction D1 and a second axial direction D2. The first axial direction D1 is a direction along the central axis Ax, and is substantially an outward direction in the vehicle width direction. The second axial direction D2 is an opposite direction to the first axial direction D1, and is substantially an inward direction in the vehicle width direction. The radial direction is a direction perpendicular to the central axis Ax. The circumferential direction is a direction around the central axis Ax.

[0018] One end of the drive shaft 32 is connected to the hub 31 and rotates integrally with the hub 31 about the central axis Ax. The drive shaft 32 transmits driving force from, for example, an engine or a motor to the hub 31. Note that when the vehicle 1 is an electric vehicle (EV), the drive shaft 32 may be the output shaft of the motor.

[0019] 2, the hat 21 has a bottom wall 41 and a peripheral wall 42. The bottom wall 41 is formed in a substantially disk shape and disposed so as to be substantially perpendicular to the axial direction. The peripheral wall 42 is formed in a substantially cylindrical shape surrounding the central axis Ax and extends from the edge of the bottom wall 41 on the radially outer side in the second axial direction D2.

[0020] The disk 22 has an annular portion 51 and a connection portion 52. The annular portion 51 is, for example, disposed so as to be substantially perpendicular to the axial direction and formed in a substantially disk shape surrounding the central axis Ax. The annular portion 51 has two side surfaces 51a, an inner edge 51b, an outer edge 51c, and an inner surface 51d. The side surface 51a may also be referred to as a sliding surface or a braking surface.

[0021] The two side surfaces 51a are located opposite to each other. One side surface 51a faces the first axial direction D1. The other side surface 51a faces the second axial direction D2. Each of the two side surfaces 51a is formed to be substantially flat. Note that the side surfaces 51a may have projections and recesses.

[0022] The inner edge 51b is located at the end of the annular portion 51 on the inside in the radial direction and is a cylindrical curved surface surrounding the central axis Ax. The inner edge 51b faces inward in the radial direction. In other words, the inner edge 51b faces the central axis Ax.

[0023] The outer edge 51c is located on the opposite side to the inner edge 51b. The outer edge 51c is located at the end of the annular portion 51 on the outer side in the radial direction, and is a substantially cylindrical curved surface arranged substantially coaxially (concentrically) with the inner edge 51b. The outer edge 51c faces outward in the radial direction.

[0024] A plurality of ventilation passages 53 are formed between the two side surfaces 51a of the annular portion 51. The ventilation passages 53 may be formed in other parts of the disk rotor 11. Each of the plurality of ventilation passages 53, for example, penetrates the annular portion 51 in a substantially radial direction. Therefore, one end of the ventilation passage 53 opens to the inner edge 51b, and the other end of the ventilation passage 53 opens to the outer edge 51c. Furthermore, as shown in FIG. 3, two ventilation passages 53 adjacent to each other in the circumferential direction communicate with each other between the inner edge 51b and the outer edge 51c. The inner surface 51d forms (defines or partitions) the ventilation passage 53. In other words, the inner surface 51d is the inner surface of the ventilation passage 53.

[0025] The ventilation passage 53 is not limited to the above example. For example, the ventilation passage 53 may extend obliquely with respect to the radial direction, may extend in a spiral shape, or may branch. The ventilation passage 53 may also open to the side surface 51a.

[0026] The annular portion 51 has two plate portions 55 and a plurality of fins 56. The plate portions 55 may also be referred to as a sliding portion. The annular portion 51 may have a plurality of pins (pillars) instead of the fins 56.

[0027] Each of the two plate portions 55 is, for example, disposed so as to be substantially perpendicular to the axial direction and formed in a substantially disk shape surrounding the central axis Ax. As shown in Fig. 2, the thickness of at least a portion of the plate portion 55 becomes thinner toward the central axis Ax. Note that the thickness of the plate portion 55 is not limited to this example.

[0028] The two plate portions 55 are spaced apart from each other in the axial direction. One plate portion 55 has one side surface 51a. The other plate portion 55 has the other side surface 51a. Each of the two plate portions 55 has a part of an inner edge 51b and a part of an outer edge 51c.

[0029] The fins 56 are located between the two plate portions 55 and connect the two plate portions 55. Each of the fins 56 extends, for example, in a substantially radial direction. In other words, the fins 56 extend substantially radially. As shown in Fig. 3, the fins 56 are arranged in two rows in the circumferential direction. Note that the arrangement of the fins 56 is not limited to this example.

[0030] Each of the two plate portions 55 and the multiple fins 56 has a part of the inner surface 51d. In other words, the two plate portions 55 and the multiple fins 56 form (define or partition) multiple ventilation passages 53. The multiple ventilation passages 53 are located, for example, between the two plate portions 55 in the axial direction and between two adjacent fins 56 in the circumferential direction.

[0031] When the disk rotor 11 rotates around the central axis Ax, for example, centrifugal force causes an airflow to pass through the ventilation passage 53. As a result, the disks 22 exchange heat with the airflow and are cooled. That is, the disk rotor 11 is an air-cooled disk rotor. Note that the disks 22 may be a single disk in which the ventilation passage 53 and the fins 56 are omitted.

[0032] 2, the connection portion 52 connects the inner edge 51b of one plate portion 55 and an end portion of the peripheral wall 42 in the second axial direction D2. The connection portion 52 is formed in a generally conical shape tapering toward the second axial direction D2. Note that the connection portion 52 is not limited to this example. Since the connection portion 52 is connected to the peripheral wall 42 of the hat 21, the hat 21 connects the disc 22 to the axle 30.

[0033] 1, the annular portion 51 of the disc 22 is disposed between the two brake pads 12. The two brake pads 12 are supported by, for example, a caliper so as to be axially movable.

[0034] Each of the two brake pads 12 has a back plate 61 and a friction material 62. The back plate 61 is disposed approximately perpendicular to the axial direction and formed in a plate shape extending approximately in the circumferential direction. The friction material 62 is attached to the back plate 61 so as to be located between the annular portion 51 and the back plate 61. A side surface 51a of the annular portion 51 faces the friction material 62 of the brake pad 12.

[0035] Fig. 4 is a cross-sectional view showing a portion of the disc rotor 11 of this embodiment. As shown in Fig. 4, the disc rotor 11 further has a hard coating 71 and an anticorrosive coating 72. The hard coating 71 is an example of a first coating. The anticorrosive coating 72 is an example of a second coating and a third coating.

[0036] The hard coating 71 is provided on the two side surfaces 51a of the disk 22. In this embodiment, the hard coating 71 covers substantially the entire area of ​​the side surface 51a. Note that the hard coating 71 may leave part of the side surface 51a exposed without covering it.

[0037] The hard coating 71 of this embodiment is a metal coating containing tungsten carbide (WC). For example, the hard coating 71 contains nickel (Ni), phosphorus (P), tungsten (W), carbon (C), and iron (Fe). However, the hard coating 71 is not limited to this example, and may contain, for example, chromium (Cr).

[0038] The hard coating 71 has higher rust resistance (which may also be referred to as corrosion resistance or rust prevention) than the disk 22. That is, the hard coating 71 is less susceptible to rust than the disk 22. In addition, the hard coating 71 is less susceptible to corrosion by chemicals than the disk 22.

[0039] Furthermore, the hard coating 71 has higher wear resistance (which may also be referred to as durability) than the disk 22. For example, the hardness of the hard coating 71 is higher than the hardness of the disk 22. Note that the hard coating 71 may have a lower hardness than the disk 22 as long as it is less susceptible to wear than the disk 22.

[0040] The anticorrosion coating 72 is provided on the surface 21a of the hat 21, the inner edge 51b, the outer edge 51c, and the inner surface 51d of the annular portion 51 of the disk 22, and the surface 52a of the connecting portion 52. The anticorrosion coating 72 of this embodiment covers substantially the entire areas of the surface 21a, the inner edge 51b, the outer edge 51c, the inner surface 51d, and the surface 52a. Note that the area on which the anticorrosion coating 72 is provided is not limited to this example.

[0041] A plurality of different types of anticorrosion coatings 72 may be provided on the surface 21a of the hat 21, the inner edge 51b, the outer edge 51c, and the inner surface 51d of the annular portion 51, and the surface 52a of the connecting portion 52. For example, the anticorrosion coating 72 provided on the surface 21a of the hat 21 and the anticorrosion coating 72 provided on the inner surface 51d of the annular portion 51 may be different from each other. Furthermore, at least a portion of the inner edge 51b, the outer edge 51c, and the inner surface 51d of the annular portion 51, and the surface 52a of the connecting portion 52 may not be covered with the anticorrosion coating 72.

[0042] The anticorrosion coating 72 is a coating that is different from the hard coating 71 in at least one of the material and the manufacturing method. The anticorrosion coating 72 is, for example, a metal coating that contains nickel (Ni) and phosphorus (P). Specifically, the anticorrosion coating 72 is nickel-phosphorus (Ni-P) plating. Note that the anticorrosion coating 72 is not limited to this example and may contain, for example, chromium (Cr) or may be a resin having rust resistance.

[0043] The anticorrosion coating 72 has higher rust resistance than the hat 21 and the disk 22. In other words, the anticorrosion coating 72 is less susceptible to rust than the hat 21 and less susceptible to rust than the disk 22. The anticorrosion coating 72 may have lower abrasion resistance than the hard coating 71. The anticorrosion coating 72 may have abrasion resistance equal to or greater than that of the hard coating 71.

[0044] 5, a method for forming the hard coating 71 and the anticorrosive coating 72, which is part of the method for manufacturing the disc brake device 10, will be described below. Note that the method for manufacturing the disc brake device 10 is not limited to the following method, and other methods may be used.

[0045] 5 is a cross-sectional view showing a part of the disc rotor 11 in the process of forming the hard coating 71 and the anticorrosive coating 72 of this embodiment. First, an electroless plating layer 81 is formed on the disc rotor 11.

[0046] The electroless plating layer 81 is a metal coating containing, for example, nickel (Ni) and phosphorus (P). The electroless plating layer 81 is formed on the surface 21a of the hat 21, the side surface 51a, the inner edge 51b, the outer edge 51c, and the inner surface 51d of the annular portion 51 of the disk 22, and the surface 52a of the connecting portion 52.

[0047] The electroless plating layer 81 is formed by, for example, electroless plating, which is wet plating. The assembled disc rotor 11 is immersed in a plating solution, whereby Ni-P plating, which is the electroless plating layer 81, is deposited on the surface 21a of the hat 21, the side surface 51a, the inner edge 51b, the outer edge 51c, and the inner surface 51d of the annular portion 51, and the surface 52a of the connecting portion 52.

[0048] 5 covers a portion of the electroless plating layer 81. The masking 83 covers the electroless plating layer 81 formed on the surface 21a of the hat 21, the inner edge 51b, the outer edge 51c, and the inner surface 51d of the annular portion 51, and the surface 52a of the connecting portion 52. On the other hand, the masking 83 does not cover the electroless plating layer 81 provided on the side surface 51a of the disk 22, leaving it exposed.

[0049] Next, an electrolytic plating layer 85 is provided on the disk rotor 11. The electrolytic plating layer 85 is, for example, a metal coating containing nickel (Ni) and tungsten (W). The electrolytic plating layer 85 covers the electroless plating layer 81 provided on the side surface 51a of the disk 22. On the other hand, the electrolytic plating layer 85 does not cover the electroless plating layer 81 provided on the surface 21a of the hat 21, the inner edge 51b, the outer edge 51c, and the inner surface 51d of the annular portion 51, and the surface 52a of the connecting portion 52.

[0050] The electrolytic plating layer 85 is formed by, for example, wet electrolytic plating. When the disk rotor 11 with the masking 83 attached thereto is immersed in a plating solution, Ni-W plating, which is the electrolytic plating layer 85, is deposited on the electroless plating layer 81 provided on the side surface 51a of the annular portion 51.

[0051] Next, the masking 83 is removed from the electroless plating layer 81. As a result, the electroless plating layer 81 provided on the surface 21a of the hat 21, the inner edge 51b, the outer edge 51c, and the inner surface 51d of the annular portion 51, and the surface 52a of the connecting portion 52 is exposed.

[0052] Alternatively, the electrolytic plating layer 85 may be formed first, and then the electroless plating layer 81 may be formed. For example, first, a masking 83 covers the surface 21a of the hat 21, the inner edge 51b, the outer edge 51c, and the inner surface 51d of the annular portion 51, and the surface 52a of the connecting portion 52. Next, the electrolytic plating layer 85 is formed on the side surface 51a of the annular portion 51. Next, the masking 83 is removed. Next, the electroless plating layer 81 is formed on the surface 21a of the hat 21, the inner edge 51b, the outer edge 51c, and the inner surface 51d of the annular portion 51, the surface 52a of the connecting portion 52, and the electroless plating layer 85 provided on the side surface 51a.

[0053] Next, the electroless plating layer 81 and the electrolytic plating layer 85 are heated by heat treatment. As a result, for example, in the electrolytic plating layer 85, tungsten (W) crystallizes and nickel (Ni) forms a solid solution containing nickel (Ni) and iron (Fe), and the electrolytic plating layer 85 becomes a composite layer. Furthermore, diffusion occurs during the heat treatment, and the electroless plating layer 81 and the electrolytic plating layer 85 provided on the side surface 51a of the annular portion 51 become one layer.

[0054] Next, the carbon concentration of the electroless plating layer 81 and the electrolytic plating layer 85 increases by gas carburization. For example, tungsten (W) in the electrolytic plating layer 85 becomes tungsten carbide (WC) which is a hard particle. As a result, the electroless plating layer 81 and the electrolytic plating layer 85 become one hard coating 71 having tungsten carbide (WC) which is a hard particle and a solid solution containing nickel (Ni) and iron (Fe). Meanwhile, the electroless plating layer 81 provided on the surface 21a of the hat 21, the inner edge 51b, the outer edge 51c, and the inner surface 51d of the annular portion 51, and the surface 52a of the connecting portion 52 becomes the anticorrosive coating 72.

[0055] As described above, the hard coating 71 is a metal coating formed by electroless nickel plating, which is electroless plating, electrolytic plating to form the electrolytic plating layer 85, which is a nickel-tungsten coating, heat treatment, and gas carburization treatment. The anticorrosion coating 72 is a metal coating formed by electroless nickel plating, which is electroless plating. In this way, the hard coating 71 and the anticorrosion coating 72 are different from each other in terms of material and manufacturing method. However, the hard coating 71 and the anticorrosion coating 72 may be made of the same material or manufactured by the same method.

[0056] When the driver brakes the vehicle 1, the piston of the caliper presses the brake pedal to apply the brakes, and the brake pad 12 is pushed toward the side surface 51a of the disc 22. As a result, the two brake pads 12 clamp the disc 22.

[0057] When the friction material 62 comes into contact with the rotating disc rotor 11, the brake pad 12 receives a circumferential force due to friction between the disc rotor 11 and the friction material 62. The brake pad 12 is supported by, for example, a caliper, and a braking torque is transmitted to the body of the vehicle 1. In this way, the disc brake device 10 brakes the disc rotor 11.

[0058] The friction material 62 of the brake pad 12 comes into contact with the hard coating 71 provided on the side surface 51a of the disc rotor 11. Therefore, friction occurs between the hard coating 71 of the disc rotor 11 and the friction material 62. The hard coating 71 has high abrasion resistance and is therefore not easily worn away by the friction. In other words, the hard coating 71 is not likely to generate particles (brake dust) caused by abrasion during braking.

[0059] Furthermore, for example, if the vehicle 1 is an EV or a hybrid vehicle (HV), the vehicle 1 can perform braking by regenerative braking. In this case, friction may occur less frequently on the side surface 51a than in a gasoline vehicle. That is, rust on the side surface 51a may progress more easily than in a gasoline vehicle. However, by providing the rust-resistant hard coating 71 on the side surface 51a, the side surface 51a is less susceptible to rust even in the case of the vehicle 1 that is an EV or HV.

[0060] An anticorrosive coating 72 is provided not only on the side surface 51a but also on the surface 21a of the hat 21, the inner edge 51b, the outer edge 51c, and the inner surface 51d of the annular portion 51, and the surface 52a of the connecting portion 52. Therefore, the entire disc rotor 11 is less susceptible to rust.

[0061] As described above, the disc rotor 11 can improve the wear resistance, so that brake dust is less likely to be generated, and for example, the environmental load can be reduced. In addition, the disc rotor 11 can improve the rust resistance, so that the risk of rusting of the disc rotor 11 caused by the electrification of the vehicle 1 can be suppressed.

[0062] If the side surface 51a of the disk 22 is covered with the anticorrosion coating 72, the anticorrosion coating 72 can make the side surface 51a of the disk 22 less susceptible to rust. However, the anticorrosion coating 72 has lower wear resistance than the hard coating 71. For this reason, the anticorrosion coating 72 may wear due to friction, and the rust resistance of the anticorrosion coating 72 may decrease. However, in this embodiment, the hard coating 71 is provided on the side surface 51a of the disk 22, so that the rust resistance of the side surface 51a can be maintained high.

[0063] In the disc brake device 10 according to the embodiment described above, the disc 22 is configured to be sandwiched between the two brake pads 12 when braking the vehicle 1. The hat 21 connects the disc 22 to the axle 30 of the vehicle 1. The hard coating 71 is a metal coating formed by electroless plating and electrolytic plating, and is provided on two side surfaces 51a of the disc 22 facing the brake pads 12. The anticorrosive coating 72 is less susceptible to rust than the hat 21, is provided on the surface 21a of the hat 21, and is a coating different from the hard coating 71 in at least one of the material and manufacturing method.

[0064] The hard coating 71 is provided on the side surface 51a of the disk 22, thereby making the side surface 51a less susceptible to rust. Furthermore, since the hard coating 71 is a metal coating formed by electroless plating and electrolytic plating, it generally has high wear resistance. Therefore, the hard coating 71 contacts the brake pad 12 when braking the vehicle 1, but wear is less likely to occur compared to when the brake pad 12 directly contacts the side surface 51a of the disk 22. That is, the hard coating 71 improves the rust resistance and wear resistance of the side surface 51a of the disk 22. Furthermore, the anticorrosive coating 72 is provided on the surface 21a of the hat 21, thereby making the surface 21a less susceptible to rust. However, the hat 21 is not a member that contacts the brake pad 12, and does not need to have high wear resistance. As described above, in the disc brake device 10, not only is the side surface 51a of the disc 22 provided with the hard coating 71 suited to the conditions of the side surface 51a, but also the surface 21a of the hat 21 is provided with the anticorrosive coating 72 suited to the conditions of the hat 21. Therefore, the disc brake device 10 can improve the rust resistance and wear resistance as a whole.

[0065] The ventilation passage 53 is formed between the two side surfaces 51a. The anticorrosive coating 72 is provided on an inner surface 51d of the ventilation passage 53. The anticorrosive coating 72 is less susceptible to rust than the disk 22, and is different from the hard coating 71 in at least one of the material and the manufacturing method.

[0066] The anticorrosive coating 72 provided on the inner surface 51d makes the inner surface 51d less susceptible to rust. However, the inner surface 51d does not come into contact with the brake pad 12 and does not need to be highly wear-resistant. As described above, not only are the hard coating 71 and the anticorrosive coating 72 provided on the side surface 51a of the disc 22 and the surface 21a of the hat 21, but the anticorrosive coating 72 is also provided on the inner surface 51d in accordance with the conditions of the inner surface 51d. Therefore, the disc brake device 10 can improve the rust resistance and wear resistance as a whole.

[0067] The hard coating 71 is a metal coating formed by electroless plating, electrolytic plating, heat treatment, and gas carburizing treatment.

[0068] For example, the diffusion caused by the heat treatment and the gas carburization process combine the electroless plating layer 81 formed by electroless plating and the electrolytic plating layer 85 formed by electrolytic plating to form a single hard coating having, for example, tungsten carbide (WC) and a solid solution containing nickel (Ni) and iron (Fe). That is, the hard coating 71 can further improve the wear resistance of the side surface 51a of the disk 22.

[0069] The electroless plating is electroless nickel plating.

[0070] For example, a nickel-phosphorus coating formed by electroless nickel plating has high rust resistance. Therefore, the hard coating 71 can improve the rust resistance of the side surface 51a of the disk 22.

[0071] Electrolytic plating forms a nickel-tungsten coating.

[0072] The nickel-tungsten coating has higher wear resistance than cast iron, which is a typical material for the disc 22 of the disc brake device 10. That is, the hard coating 71 can further improve the wear resistance of the side surface 51a of the disc 22. Furthermore, although tungsten is generally expensive, the disc brake device 10 can reduce costs by not providing the nickel-tungsten coating on the hat 21.

[0073] The disc brake device according to at least one embodiment described above includes, as an example, a disc configured to be sandwiched between two brake pads when braking the vehicle, a hat connecting the disc to the axle of the vehicle, a first coating formed by electroless plating and electrolytic plating on two side surfaces of the disc facing the brake pads, and a second coating formed on the surface of the hat, which is less susceptible to rust than the hat and is different from the first coating in at least one of the material and manufacturing method. Thus, as an example, the first coating is provided on the side surface of the disc, making the side surface less susceptible to rust. Furthermore, since the first coating is a metal coating formed by electroless plating and electrolytic plating, it generally has high wear resistance. Therefore, although the first coating comes into contact with the brake pads when braking the vehicle, wear is less likely to occur compared to when the brake pads directly come into contact with the side surface of the disc. In other words, the first coating improves the rust resistance and wear resistance of the side surface of the disc. Furthermore, the second coating is provided on the surface of the hat, making the surface less susceptible to rust. However, the hat is not a member that comes into contact with the brake pad, and does not need to be highly wear-resistant. As described above, the disc brake device not only has a first coating provided on the side surface of the disc according to the conditions of the side surface, but also has a second coating provided on the surface of the hat according to the conditions of the hat. Therefore, the disc brake device can improve the rust resistance and wear resistance as a whole.

[0074] As an example, the above-mentioned disc brake device further includes a ventilation passage formed between the two side surfaces, and the third coating, which is less prone to rust than the disc and differs from the first coating in at least one of material and manufacturing method, is provided on the inner surface of the ventilation passage. Thus, as an example, the third coating is provided on the inner surface of the ventilation passage, making the inner surface less prone to rust. However, the inner surface does not contact the brake pad and does not need to be highly wear-resistant. As described above, not only are the first coating and the second coating provided on the side surface and the surface of the hat of the disc, but the third coating according to the conditions of the inner surface is provided on the inner surface of the ventilation passage. Therefore, the disc brake device can improve the rust resistance and wear resistance as a whole.

[0075] In the above-mentioned disc brake device, as an example, the first coating is a metal coating formed by the electroless plating, the electrolytic plating, heat treatment, and gas carburization treatment. Therefore, as an example, the coating formed by the electroless plating and the coating formed by the electrolytic plating become one hard coating having, for example, tungsten carbide (WC) and a solid solution containing nickel (Ni) and iron (Fe) by the diffusion caused by the heat treatment and the gas carburization treatment. That is, the first coating can further improve the wear resistance of the side surface of the disc.

[0076] In the above-mentioned disc brake device, as an example, the electroless plating is electroless nickel plating. Therefore, as an example, for example, a nickel-phosphorus coating formed by electroless nickel plating has high rust resistance. Therefore, the first coating can improve the rust resistance of the side surface of the disc.

[0077] In the above-mentioned disc brake device, as an example, the electrolytic plating forms a nickel-tungsten coating. Thus, as an example, the nickel-tungsten coating has higher wear resistance than cast iron, which is a common material for discs in disc brake devices. That is, the first coating can further improve the wear resistance of the side surface of the disc. In addition, although tungsten is generally expensive, the disc brake device can reduce costs by not providing the nickel-tungsten coating on the hat.

[0078] The manufacturing method of the disc brake device according to at least one embodiment described above includes, as an example, forming a first coating, which is a metal coating, by electroless plating and electrolytic plating on a side of the disc of the disc rotor that faces the brake pad, and forming a second coating, which is less susceptible to rust than the hat and is different from the first coating in at least one of material and manufacturing method, on a surface of the hat that connects the disc of the disc rotor to the axle of the vehicle. Thus, as an example, the rust resistance and wear resistance of the disc brake device as a whole can be improved.

[0079] Although the embodiments of the present invention have been illustrated above, the above-mentioned embodiments and modifications are merely examples and are not intended to limit the scope of the invention. The above-mentioned embodiments and modifications can be implemented in various other forms, and various omissions, substitutions, combinations, and modifications can be made without departing from the gist of the invention. In addition, the configurations and shapes of each embodiment and each modification can be partially replaced and implemented. [Explanation of symbols]

[0080] 10...disc brake device, 12...brake pad, 21...hat, 21a...surface, 22...disc, 30...axle, 51a...side, 51d...inner surface, 53...ventilation passage, 71...hard coating (first coating), 72...corrosion prevention coating (second coating, third coating).

Claims

1. A disc configured to be sandwiched between two brake pads when braking a vehicle; a hat connecting said disk to an axle of said vehicle; a first coating formed by electroless plating and electrolytic plating on two sides of the disk facing the brake pad; a second coating which is less susceptible to rust than the hat and is provided on the surface of the hat and which is different from the first coating in at least one of material and manufacturing method; A disc brake device comprising:

2. A ventilation passage formed between the two side surfaces, a third coating, which is less susceptible to rust than the disk and is different from the first coating in at least one of material and manufacturing method, is provided on the inner surface of the ventilation passage; The disc brake device of claim 1.

3. the first coating is a metal coating formed by the electroless plating, the electrolytic plating, a heat treatment, and a gas carburizing treatment; The disc brake device of claim 1.

4. The electroless plating is electroless nickel plating. The disc brake device of claim 1.

5. The electrolytic plating forms a nickel-tungsten coating. The disc brake device of claim 1.

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