Disc brake device

Abstract

A disc brake device according to an embodiment comprises, for example: a disc that is configured to be clamped between two brake pads when braking a vehicle; a hat that connects the disc to an axle of the vehicle; a first coating that is a metal coating formed by electroless plating and electrolytic plating, and is provided 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 a surface of the hat, and differs from the first coating in at least one of a material and a manufacturing method.

Description

disc brake device

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

[0002] Disc brake devices that apply brakes to a vehicle by clamping a disc rotor with brake pads are known. The disc rotor includes, for example, a disc clamped between the brake pads and a hat connected to an axle. The disc surface may be coated with a coating to improve corrosion resistance, for example (see Patent Document 1).

[0003] Special Publication No. 2021-510409

[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 entire disk brake device.

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

[0006] A disc brake device according to an embodiment of the present invention, for example, includes a disc configured to be sandwiched between two brake pads during vehicle braking, a hat connecting the disc to an axle of the vehicle, a first coating formed by electroless plating and electrolytic plating and disposed on two sides of the disc facing the brake pads, and a second coating that is less susceptible to rust than the hat and is disposed on the surface of the hat, differing from the first coating in at least one of material and manufacturing method. Thus, for example, the first coating improves the rust resistance and wear resistance of the sides of the disc. Furthermore, the second coating improves the rust resistance of the surface of the hat. Therefore, the disc brake device as a whole can have improved rust resistance and wear resistance.

[0007] Fig. 1 is a cross-sectional view schematically showing a disc brake device according to one embodiment. Fig. 2 is a cross-sectional view showing a disc rotor according to the embodiment. Fig. 3 is a cross-sectional view showing the disc rotor according to the embodiment along line F3-F3 in Fig. 2. Fig. 4 is a cross-sectional view showing a portion of the disc rotor according to the embodiment. Fig. 5 is a cross-sectional view showing a portion of the disc rotor during the process of forming a hard coating and an anticorrosion coating according to the embodiment.

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

[0009] In the following description, "suppress" is defined as, for example, preventing an event, action, or influence from occurring, 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 schematically 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 disc rotor 11 of this embodiment. Fig. 3 is a cross-sectional view showing the disc rotor 11 of this embodiment taken along line F3-F3 in Fig. 2. As shown in Fig. 2, the disc rotor 11 is formed in an overall hat shape.

[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 includes 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 includes, 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 suspension knuckle 35 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 width direction of the vehicle 1. When turning, the direction in which the central axis Ax of the front wheel extends is inclined obliquely with respect to the width direction of the vehicle.

[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 a direction opposite 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 around the central axis Ax. The drive shaft 32 transmits driving force from, for example, an engine or a motor to the hub 31. If 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 generally disk shape and is disposed so as to be generally perpendicular to the axial direction. The peripheral wall 42 is formed in a generally 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 connecting portion 52. The annular portion 51 is, for example, arranged 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 surfaces 51a may also be referred to as a sliding surface or a braking surface.

[0021] The two side surfaces 51a are located on opposite sides 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 irregularities.

[0022] The inner edge 51b is located at the radially inner end of the annular portion 51 and has a cylindrical curved surface that surrounds 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 of 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 has a substantially cylindrical curved surface that is substantially coaxial (concentric) 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 also be formed in other portions 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 passages 53. In other words, the inner surface 51d is the inner surface of the ventilation passage 53.

[0025] The ventilation passages 53 are not limited to the above example. For example, the ventilation passages 53 may extend obliquely relative to the radial direction, may extend in a spiral shape, or may branch. Furthermore, the ventilation passages 53 may open on the side surface 51 a.

[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 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. However, 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 51 a. The other plate portion 55 has the other side surface 51 a. Each of the two plate portions 55 has a part of an inner edge 51 b and a part of an outer edge 51 c.

[0029] The fins 56 are positioned 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. However, the arrangement of the fins 56 is not limited to this example.

[0030] Each of the two plate portions 55 and the plurality of fins 56 has a portion of the inner surface 51d. In other words, the two plate portions 55 and the plurality of fins 56 form (define or partition) a plurality of ventilation passages 53. The plurality of 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, an airflow passes through the ventilation passage 53 due to, for example, centrifugal force. As a result, the disks 22 exchange heat with the airflow and are cooled. In other words, the disk rotor 11 is an air-cooled disk rotor. Note that the disks 22 may be a single disk, omitting the ventilation passage 53 and the fins 56.

[0032] As shown in Figure 2, the connecting portion 52 connects the inner edge 51b of one plate portion 55 to the end of the peripheral wall 42 in the second axial direction D2. The connecting portion 52 is formed in a generally conical shape that tapers toward the second axial direction D2. Note that the connecting portion 52 is not limited to this example. Because the connecting 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 substantially perpendicular to the axial direction and is formed in a plate shape extending substantially 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 51 a of the annular portion 51 faces the friction material 62 of the brake pad 12.

[0035] Figure 4 is a cross-sectional view showing a portion of the disc rotor 11 of this embodiment. As shown in Figure 4, the disc rotor 11 further has a hard coating 71 and an anticorrosion coating 72. The hard coating 71 is an example of a first coating. The anticorrosion 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 51 a of the disk 22. In this embodiment, the hard coating 71 covers almost the entire area of ​​the side surface 51 a. Note that the hard coating 71 may leave a portion of the side surface 51 a exposed.

[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. The hard coating 71 is also 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, outer edge 51c, and 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 surface 21a, inner edge 51b, outer edge 51c, inner surface 51d, and surface 52a. However, 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, outer edge 51c, and 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 may be different from the anticorrosion coating 72 provided on the inner surface 51d of the annular portion 51. Furthermore, at least a portion of the inner edge 51b, outer edge 51c, and 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 differs from the hard coating 71 in at least one of the material and manufacturing method. The anticorrosion coating 72 is, for example, a metal coating containing nickel (Ni) and phosphorus (P). Specifically, the anticorrosion coating 72 is nickel-phosphorus (Ni-P) plating. However, the anticorrosion coating 72 is not limited to this example and may contain, for example, chromium (Cr), or may be a rust-resistant resin.

[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. However, 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 anticorrosion 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 also 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 anticorrosion 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) and is formed on the surface 21 a of the hat 21, the side surface 51 a, inner edge 51 b, outer edge 51 c, and inner surface 51 d of the annular portion 51 of the disk 22, and the surface 52 a of the connecting portion 52.

[0047] The electroless plating layer 81 is formed by, for example, electroless plating, which is wet plating. By immersing the assembled disk rotor 11 in a plating solution, Ni—P plating, which is the electroless plating layer 81, is deposited on the surface 21 a of the hat 21, the side surface 51 a, inner edge 51 b, outer edge 51 c, and inner surface 51 d of the annular portion 51, and the surface 52 a 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 a metal coating containing, for example, nickel (Ni) and tungsten (W). The electrolytic plating layer 85 covers the electroless plating layer 81 provided on the side surface 51 a 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 21 a of the hat 21, the inner edge 51 b, the outer edge 51 c, and the inner surface 51 d of the annular portion 51, and the surface 52 a 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 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 51 a of the annular portion 51.

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

[0052] Alternatively, the electrolytic plating layer 85 may be formed first, followed by the electroless plating layer 81. 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 plated layer 81 and the electrolytic plated layer 85 are heated by heat treatment. As a result, for example, tungsten (W) in the electrolytic plated layer 85 crystallizes, and nickel (Ni) forms a solid solution containing nickel (Ni) and iron (Fe), turning the electrolytic plated layer 85 into a composite layer. Furthermore, diffusion occurs during the heat treatment, and the electroless plated layer 81 and the electrolytic plated layer 85 provided on the side surface 51 a of the annular portion 51 become a single layer.

[0054] Next, the carbon concentration of the electroless plated layer 81 and the electrolytic plated layer 85 is increased by gas carburizing. For example, the tungsten (W) in the electrolytic plated layer 85 becomes tungsten carbide (WC), which is a hard particle. As a result, the electroless plated layer 81 and the electrolytic plated layer 85 become a single hard coating 71 containing tungsten carbide (WC), which is a hard particle, and a solid solution containing nickel (Ni) and iron (Fe). Meanwhile, the electroless plated 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 a corrosion-resistant 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 carburizing treatment. The anticorrosion coating 72 is a metal coating formed by electroless nickel plating, which is electroless plating. Thus, the hard coating 71 and the anticorrosion coating 72 differ from each other in terms of material and manufacturing method. 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 pads 12 press the brake pads 12 against the side surfaces 51a of the discs 22. As a result, the two brake pads 12 clamp the discs 22.

[0057] When the friction material 62 comes into contact with the rotating disc rotor 11, friction between the disc rotor 11 and the friction material 62 causes the brake pad 12 to receive a circumferential force. The brake pad 12 is supported by, for example, a caliper, and 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 51 a of the disc rotor 11. As a result, 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 less likely to wear away due to this friction. In other words, the hard coating 71 is less likely to produce particles (brake dust) caused by wear during braking.

[0059] Furthermore, for example, if the vehicle 1 is an EV or hybrid vehicle (HV), the vehicle 1 can brake using regenerative braking. In this case, friction may occur less frequently on the side surface 51a than in a gasoline-powered vehicle. That is, rust on the side surface 51a may progress more easily than in a gasoline-powered 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 an EV or HV vehicle 1.

[0060] The anticorrosion 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, outer edge 51c, and inner surface 51d of the annular portion 51, and the surface 52a of the connecting portion 52. This makes the entire disc rotor 11 less susceptible to rust.

[0061] As described above, the disc rotor 11 can have improved wear resistance, which reduces brake dust generation and, for example, can reduce environmental impact. Furthermore, the disc rotor 11 can have improved rust resistance, which can prevent the risk of disc rotor 11 rusting, which would otherwise increase due to the electrification of the vehicle 1.

[0062] If the side surface 51 a of the disk 22 were covered with the anticorrosion coating 72, the anticorrosion coating 72 could make the side surface 51 a of the disk 22 less susceptible to rust. However, the anticorrosion coating 72 has lower wear resistance than the hard coating 71. Therefore, the anticorrosion coating 72 could be worn away by friction, reducing the rust resistance of the anticorrosion coating 72. However, in this embodiment, by providing the hard coating 71 on the side surface 51 a of the disk 22, the rust resistance of the side surface 51 a can be maintained at a high level.

[0063] In the disc brake device 10 according to the embodiment described above, the disc 22 is configured to be sandwiched between 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 that face the brake pads 12. The anticorrosion 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 that differs from the hard coating 71 in at least one of material and manufacturing method.

[0064] The hard coating 71 is provided on the side surface 51 a of the disc 22, making the side surface 51 a 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, although the hard coating 71 comes into contact with the brake pad 12 when braking the vehicle 1, it is less susceptible to wear than when the brake pad 12 directly contacts the side surface 51 a of the disc 22. In other words, the hard coating 71 improves the rust resistance and wear resistance of the side surface 51 a of the disc 22. Furthermore, the anticorrosion coating 72 is provided on the surface 21 a of the hat 21, making the surface 21 a less susceptible to rust. However, the hat 21 is not a component that comes into contact with the brake pad 12, and therefore does not need to have high wear resistance. As described above, in the disc brake device 10, not only is the side surface 51 a of the disc 22 provided with the hard coating 71 suited to the conditions of the side surface 51 a, but the surface 21 a of the hat 21 is provided with the anticorrosion coating 72 suited to the conditions of the hat 21. Therefore, the disc brake device 10 can improve its overall rust resistance and wear resistance.

[0065] The ventilation passage 53 is formed between the two side surfaces 51 a. The anticorrosion coating 72 is provided on an inner surface 51 d of the ventilation passage 53. The anticorrosion 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 anticorrosion 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 anticorrosion coating 72 provided on the side surface 51a of the disc 22 and the surface 21a of the hat 21, but the anticorrosion 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 its overall rust resistance and wear resistance.

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

[0068] For example, due to diffusion caused by heat treatment and gas carburizing treatment, the electroless plating layer 81 formed by electroless plating and the electrolytic plating layer 85 formed by electrolytic plating become a single hard coating containing, for example, tungsten carbide (WC) and a solid solution containing nickel (Ni) and iron (Fe). In other words, the hard coating 71 can further improve the wear resistance of the side surface 51 a 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, so the hard coating 71 can improve the rust resistance of the side surface 51 a 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. In other words, the hard coating 71 can further improve the wear resistance of the side surface 51 a of the disc 22. Furthermore, although tungsten is generally expensive, not providing the nickel-tungsten coating on the hat 21 allows the disc brake device 10 to reduce costs.

[0073] At least one embodiment of the disc brake device described above includes, for example, a disc configured to be sandwiched between two brake pads during vehicle braking, a hat connecting the disc to an axle of the vehicle, a first coating formed by electroless plating and electrolytic plating and disposed on two sides of the disc facing the brake pads, and a second coating formed on the surface of the hat and differing in at least one of material and manufacturing method from the first coating, and being more rust-resistant than the hat. Thus, for example, the first coating is disposed on the side of the disc, thereby making the side surface rust-resistant. Furthermore, because 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 contacts the brake pads during vehicle braking, it is less likely to wear compared to when the brake pads directly contact the side of the disc. In other words, the first coating improves the rust resistance and wear resistance of the side 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 component 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 its overall rust resistance and wear resistance.

[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 is made of a different material and / or manufacturing method than the first coating, 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 come into contact with the brake pad, and does not need to be highly wear-resistant. As described above, not only are the first and second coatings provided on the side surfaces and hat surface of the disc, but a third coating corresponding to the conditions of the inner surface is provided on the inner surface of the ventilation passage. Therefore, the disc brake device can improve its overall rust resistance and wear resistance.

[0075] In the above-described disc brake device, for example, the first coating is a metal coating formed by the electroless plating, the electrolytic plating, heat treatment, and gas carburizing treatment. Therefore, for example, due to the diffusion caused by the heat treatment and the gas carburizing treatment, the coating formed by the electroless plating and the coating formed by the electrolytic plating become a single hard coating containing, for example, tungsten carbide (WC) and a solid solution containing nickel (Ni) and iron (Fe). In other words, the first coating can further improve the wear resistance of the side surface of the disc.

[0076] In the above-described disc brake device, for example, the electroless plating is electroless nickel plating. Therefore, 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-described disc brake device, as one example, the electrolytic plating forms a nickel-tungsten coating. Therefore, as one example, the nickel-tungsten coating has higher wear resistance than cast iron, which is a common material for discs in disc brake devices. In other words, the first coating can further improve the wear resistance of the side surface of the disc. Furthermore, although tungsten is generally expensive, not providing a nickel-tungsten coating on the hat allows the disc brake device to reduce costs.

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

[0079] While the embodiments of the present invention have been described above, the above-described embodiments and modifications are merely examples and are not intended to limit the scope of the invention. The above-described embodiments and modifications can be implemented in various other forms, and various omissions, substitutions, combinations, and modifications can be made without departing from the spirit of the invention. Furthermore, the configurations and shapes of each embodiment and each modification can be partially interchanged.

Claims

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

2. The disc brake device of claim 1, further comprising a ventilation passage formed between said two side surfaces, and a third coating is provided on the inner surface of said ventilation passage, said third coating being less prone to rust than said disc and differing from said first coating in at least one of material and manufacturing method.

3. The disk brake device according to claim 1, wherein the first coating is a metal coating formed by the electroless plating, the electrolytic plating, a heat treatment, and a gas carburizing treatment.

4. The disc brake device according to claim 1, wherein the electroless plating is electroless nickel plating.

5. The disk brake device according to claim 1, wherein the electrolytic plating forms a nickel-tungsten coating.

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