Opposed piston type monoblock brake caliper, and manufacturing method for opposed piston type monoblock brake caliper

Abstract

An opposed piston type monoblock brake caliper (1) is integrally formed from a metal. The brake caliper (1) is provided with a first body (3) provided on one side and a second body (4) provided on the other side with a disk accommodation space (2) therebetween. The brake caliper (1) is also provided with a first bridge part (5) and a second bridge part (6) that connect the first body (3) with the second body (4). A brake fluid path (10) is formed inside the first body (3), the second body (4), and the first bridge part (5) so as to connect first cylinders (81) in the first body (3) with second cylinders (82) in the second body (4). A bleeder path (12) to which a bleeder bolt (11) is attached is formed inside the first bridge part (5). The bleeder path (12) is connected to a small cross-sectional segment (10X) of the brake fluid path (10) inside the first bridge part (5).

Description

Opposed piston type monoblock brake caliper and method for manufacturing opposed piston type monoblock brake caliper

[0001] The present invention relates to an opposed-piston monoblock brake caliper and a method for manufacturing an opposed-piston monoblock brake caliper.

[0002] The following Patent Documents 1 and 2 are Japanese patent application publications filed by the same applicant and disclose an opposed-piston monoblock brake caliper formed integrally. Monoblock brake calipers have high rigidity and are capable of suppressing deformation during braking, thereby achieving high braking performance. The brake caliper disclosed in Patent Document 1 is manufactured by casting. The drawings in Patent Document 1 do not show a brake fluid path (though an explanation is given in paragraph

[0022] of Patent Document 1). However, according to the disclosure of Patent Document 2, two brake fluid paths are formed inside the caliper (see [Figure 3] and paragraphs

[0012] to

[0013] of Patent Document 2).

[0003] The caliper is equipped with two sets of opposing pistons. One of the two brake fluid paths connects two piston cylinders on one side and extends obliquely toward the other side, opening at the other side. The other of the two brake fluid paths connects two piston cylinders on the other side and extends obliquely toward the other side, opening at the one side. One path and the other path are formed substantially symmetrically with respect to the center plane of the brake disc, and their inclined portions intersect inside the caliper. A brake pipe from a brake master cylinder is connected to the open end of one path, and a bleeder bolt is attached to the open end of the other path.

[0004] Japanese Unexamined Patent Publication No. 2012-63528 Japanese Unexamined Patent Application No. 10-30660

[0005] If air remains inside the brake fluid passage in the brake caliper, the hydraulic pressure transmitted by the brake fluid will not be properly transmitted to the piston. Therefore, when refilling or replacing the brake fluid, the air in the brake fluid passage is expelled as much as possible using the bleeder bolt. In addition, it is also necessary to prevent air from entering the brake fluid passage not only when refilling or replacing the brake fluid. In other words, when designing the brake fluid passage, it is necessary to consider preventing air from remaining inside the brake fluid passage.

[0006] An object of the present invention is to provide an opposed-piston monoblock brake caliper that can effectively prevent air from accumulating in the brake fluid path. Another object of the present invention is to provide a method for manufacturing a brake caliper that can effectively prevent air from accumulating in the brake fluid path.

[0007] A first aspect of the present invention provides an opposed-piston monoblock brake caliper integrally formed from metal. The brake caliper includes a first body provided on one side of a disc accommodating space that accommodates a brake disc, and a second body provided on the other side. The brake caliper also includes a first bridge portion connecting the first body and the second body at one end of the disc accommodating space, and a second bridge portion connecting the first body and the second body at the other end. A brake fluid path is formed inside the first body, the second body, and the first bridge portion to connect the first cylinder of the first body and the second cylinder of the second body. A bleeder path is formed inside the first bridge portion, one end of which is connected to the brake fluid path and the other end of which is attached to a bleeder bolt. The bleeder path is connected to the brake fluid path inside the first bridge portion. The brake fluid path inside the first bridge portion includes a small cross-sectional area section having a cross-sectional area smaller than the cross-sectional areas of the other sections. The small cross-sectional area section is in communication with the bleeder path.

[0008] A second aspect of the present invention provides a method for manufacturing an opposed-piston monoblock brake caliper. The brake caliper manufactured by this method includes a first body provided on one side of a disc accommodating space that accommodates a brake disc, and a second body provided on the other side. The brake caliper also includes a first bridge portion connecting the first body and the second body at one end of the disc accommodating space, and a second bridge portion connecting the first body and the second body at the other end. The brake caliper is integrally formed from metal by three-dimensional printing, while a brake fluid path connecting the first cylinder of the first body and the second cylinder of the second body is formed inside the first body, the second body, and the first bridge portion.

[0009] According to the above feature, it is possible to effectively prevent air from accumulating in the brake fluid path.

[0010] FIG. 1 is a perspective view of an opposed-piston monoblock brake caliper according to a first embodiment. FIG. 2 is a rear view of the brake caliper. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. FIG. 4 is an enlarged cross-sectional view of part IV in FIG. 3. FIG. 5 is a perspective view of an opposed-piston monoblock brake caliper according to a second embodiment. FIG. 6 is a cross-sectional view (cross-sectional view taken along line VI-VI in FIG. 2) of an opposed-piston monoblock brake caliper according to a third embodiment. FIG. 7 is a perspective view of an opposed-piston monoblock brake caliper according to a fourth embodiment. FIG. 8 is a rear view of the brake caliper.

[0011] An opposed-piston monoblock brake caliper according to an embodiment and a manufacturing method thereof will now be described with reference to the drawings. First, a brake caliper according to a first embodiment will be described with reference to FIGS. 1 to 4.

[0012] The brake caliper 1 according to the first embodiment is a so-called "monoblock" brake caliper that is integrally formed from metal. Metal monoblock calipers can also be manufactured by casting or cutting, but the brake caliper 1 according to this embodiment is manufactured by three-dimensional printing (hereinafter simply referred to as "3D printing"). The method of manufacturing the brake caliper 1 by 3D printing will be described later.

[0013] The brake caliper 1 according to this embodiment is an "opposed piston type" brake caliper incorporating two pairs of opposed pistons. Figures 1 to 4 show a brake caliper 1 that does not incorporate pistons. However, the brake caliper 1 shown in Figures 1 to 4 is fitted with a bleeder bolt 11, which will be described later. Also, the brake disc that is sandwiched between the opposed pistons is not shown in the drawings. The brake caliper 1 shown in Figures 1 to 4 is a brake caliper for the front wheels of a four-wheeled vehicle.

[0014] The brake caliper 1 includes a first body 3 provided on one side (the left side in FIG. 1 ) and a second body 4 provided on the other side (the right side in FIG. 1 ) of a disc accommodating space 2 that accommodates a brake disc. The brake caliper 1 also includes a first bridge portion 5 provided on one end side (the right end side in FIG. 2 ) of the disc accommodating space 2, and a second bridge portion 6 provided on the other end side (the left end side in FIG. 2 ). As described above, the brake caliper 1 is a monoblock brake caliper, and therefore the first body 3, second body 4, first bridge portion 5, and second bridge portion 6 are made integrally.

[0015] When the brake caliper 1 is mounted on a vehicle, the first body 3 is disposed inside the vehicle, and the second body 4 is disposed outside. The above-mentioned disc accommodating space 2 is formed between the first body 3 and the second body 4. A brake pad accommodating recess 7 is formed on the inner surface of the first body 3 facing the disc accommodating space 2. Two first cylinders 81, each accommodating two first pistons (not shown), are formed on the inner surface of the brake pad accommodating recess 7, lined up in the circumferential direction of the brake disc.

[0016] 1 and 2 , a pair of brackets 9 for fixing the brake caliper 1 to a suspension part such as a hub carrier are also integrally formed at the bottom of the first body 3. Symmetrically to the first body 3, a brake pad accommodating recess 7 is formed on the inner surface of the second body 4 facing the disc accommodating space 2. Two cylindrical second cylinders 82, each accommodating two second pistons (not shown), are formed side by side in the circumferential direction of the brake disc on the inner surface of the brake pad accommodating recess 7. The second pistons in the second cylinder 82 face the first pistons in the first cylinder 81.

[0017] The first bridge portion 5 connects the first body 3 and the second body 4 across the disc accommodating space 2. The second bridge portion 6 similarly connects the first body 3 and the second body 4 across the disc accommodating space 2. In Figures 1 and 2, the disc accommodating space 2 and the brake pad accommodating recess 7 are open at the top. A part (not shown) that holds the brake pads is attached to this open portion.

[0018] The brake caliper 1 also includes a brake fluid path 10 formed inside the first body 3, the second body 4, and the first bridge portion 5 to connect the first cylinder 81 and the second cylinder 82. The brake fluid path 10 also connects the two first cylinders 81 to each other. The brake fluid path 10 also connects the two second cylinders 82 to each other. Looking at only this section of the brake fluid path 10, it appears to be U-shaped. However, in this embodiment, the brake fluid path 10 is also formed inside the second bridge portion 6 to connect the first cylinder 81 and the second cylinder 82, and as a whole forms a circular path.

[0019] A bleeder path 12 is also formed inside the first bridge portion 5, one end of which is connected to the brake fluid path 10 and the other end of which has a bleeder bolt 11 attached. Therefore, the bleeder path 12 is connected to the brake fluid path 10 inside the first bridge portion 5. A brake fluid discharge path is formed inside the bleeder bolt 11, and this discharge path is connected to the bleeder path 12 by loosening the bleeder bolt 11. When the bleeder bolt 11 is tightened, the bleeder path 12 is closed. When refilling or replacing brake fluid, air is discharged from the brake fluid path 10 through the bleeder path 12 using the bleeder bolt 11. Note that the bleeder bolt 11 in the figure has a rubber cap to prevent foreign matter such as sand and water from getting in, and an O-ring to prevent brake fluid leakage.

[0020] The brake fluid path 10 within the first bridge portion 5 has a small cross-sectional area section 10X formed therein, the cross-sectional area of ​​which is smaller than the cross-sectional area of ​​the other sections of the brake fluid path 10 (excluding an orifice 14, which will be described later). In other words, the inner diameter of the small cross-sectional area section 10X is smaller than the inner diameters of the other sections of the brake fluid path 10. The bleeder path 12 is directly connected to this small cross-sectional area section 10X. The cross-sectional area of ​​the bleeder path 12 is also the same as the cross-sectional area of ​​the small cross-sectional area section 10X. More specifically, the small cross-sectional area section 10X and the bleeder path 12 are arranged in a straight line, and a small cross-sectional area path is formed in a straight line from the small cross-sectional area section 10X to the bleeder path 12. The advantages of providing the small cross-sectional area section 10X will be described later.

[0021] A fluid introduction path 13 connected to a brake pipe extending from the brake master cylinder is also formed inside the first body 3. As shown in Fig. 4, one end of the fluid introduction path 13 is connected to the brake fluid path 10 between the two first cylinders 81. In this embodiment, orifices 14, the inner diameter of which is locally narrowed, are formed in the fluid introduction path 13 between each of the two first cylinders 81 and the other end (open end) of the fluid introduction path 13. More specifically, in the section of the brake fluid path 10 between the two first cylinders 81, an orifice 14 is formed immediately before one of the first cylinders 81, and another orifice 14 is formed immediately before the other first cylinder 81.

[0022] The orifice 14 locally narrows the cross-sectional area of ​​the brake fluid path 10. The orifice 14 acts as a flow resistance for the fluid and can slightly delay the buildup of brake fluid pressure in the brake caliper 1. The advantages of forming the orifice 14 will be explained later. Note that a single orifice 14 may be provided on the fluid introduction path 13. In this case as well, an orifice 14 is formed between each of the two first cylinders 81 and the other end (open end) of the fluid introduction path 13.

[0023] In the brake caliper 1 according to this embodiment, which is integrally formed by the first body 3, the second body 4, the first bridge portion 5, and the second bridge portion 6, a brake fluid path 10 is formed inside the first body 3, the second body 4, and the first bridge portion 5. A bleeder path 12 is also formed inside the first bridge portion 5, one end of which is connected to the brake fluid path 10 and the other end of which is fitted with a bleeder bolt 11. The bleeder path 12 is connected to the brake fluid path 10 inside the first bridge portion 5. A small cross-sectional area section 10X is formed in the brake fluid path 10 inside the first bridge portion 5, and the cross-sectional area is smaller than the cross-sectional area of ​​the other sections of the brake fluid path 10. The small cross-sectional area section 10X is in communication with the bleeder path 12.

[0024] The bleeder path 12, to which the bleeder bolt 11 is attached, is connected to the highest position of the brake fluid path 10 when the brake caliper 1 is mounted on the vehicle, due to its function of discharging air from the brake fluid path 10. When bleeding air from the brake fluid path 10, air accumulates in the small cross-sectional area section 10X, which is located at the highest position, and in the bleeder path 12. This air is discharged through the small cross-sectional area section 10X and the bleeder path 12 by brake fluid supplied from the large cross-sectional area section of the brake fluid path 10 to the small cross-sectional area section 10X. Because the cross-sectional area of ​​the discharge path terminal is reduced, air is less likely to remain in the small cross-sectional area section 10X and the bleeder path 12. Furthermore, the flow rate of the brake fluid increases in the small cross-sectional area section 10X and the bleeder path 12, making it easier for the air to be discharged together with the brake fluid. As a result, air accumulation in the brake fluid path 10, including the small cross-sectional area section 10X, can be effectively prevented.

[0025] In particular, in this embodiment, the small cross-sectional area section 10X and the bleeder path 12 are formed in a straight line, which facilitates the discharge of air and the discharge of brake fluid mixed with air.

[0026] According to the brake caliper 1 of this embodiment, the brake fluid path 10 is also formed inside the second bridge portion 6 to form a circular path. Therefore, there are no dead ends in the brake fluid path 10, and air in the brake fluid path 10 can be reliably discharged through the single bleeder path 12. That is, because the brake fluid path 10 forms a circular path, brake fluid can flow from both the brake fluid path 10 in the first body 3 and the brake fluid path 10 in the second body 4 to the bleeder path 12 and be reliably discharged through the bleeder path 12. Furthermore, because the cross-sectional area of ​​the small cross-sectional area section 10X is small, i.e., its inner diameter is small, fluid flow resistance in the small cross-sectional area section 10X increases. However, hydraulic pressure is reliably transmitted to the second cylinder 82 without delay by the brake fluid path 10 in the second bridge portion 6.

[0027] In a monoblock brake caliper, instead of the brake fluid path 10 inside the first bridge portion 5 (or second bridge portion 6) of this embodiment, it is also possible to arrange a pipe outside the brake caliper. However, using a pipe requires flare bolts for fastening, increasing the number of parts. It also increases the number of pipe installation steps and requires management of the fastening parts. There is also the possibility of the pipe being damaged by contact with the road wheel when changing the road wheel. If the fastening part of the pipe loosens, there is a concern that air or foreign matter may enter through the fastening part. If the entire brake fluid path 10 is formed inside the brake caliper 1, as in this embodiment, all of these concerns are eliminated.

[0028] Furthermore, with the brake caliper 1 of this embodiment, one end of the fluid introduction path 13 is connected to the brake fluid path 10, and the other end is connected to the brake piping. An orifice 14 is formed in each section of the brake fluid path 10 that directly connects one end of the fluid introduction path 13 to the two first cylinders 81. This delays the buildup of brake fluid pressure in the brake caliper 1. As described above, if the brake caliper 1 equipped with the orifice 14 of this embodiment is used on the front wheels and a brake caliper without an orifice is used on the rear wheels, the rear wheels will build up hydraulic pressure slightly earlier during braking. This prevents a deterioration in the vehicle's straight-line stability during braking, stabilizing vehicle behavior. Furthermore, building up hydraulic pressure on the rear wheels earlier can prevent the vehicle from nose-diving.

[0029] Because the orifice 14 is provided to delay the rise of brake fluid pressure in the brake caliper 1 in which the orifice 14 is formed, the above-mentioned advantages are similarly obtained even if a single orifice 14 is formed in the fluid introduction path 13. Furthermore, the position of the orifice 14 can vary depending on the connection position of one end of the fluid introduction path 13 to the brake fluid path 10. For example, if one end of the fluid introduction path 13 is connected to the brake fluid path 10 between the first cylinder 81 and the second cylinder 82, one end of the fluid introduction path 13 is directly connected to both the first cylinder 81 and the second cylinder 82. In such a case, the orifice 14 is provided in the section of the brake fluid path 10 that directly connects one end of the fluid introduction path 13 to the first cylinder 81. At the same time, another orifice 14 is provided in the section of the brake fluid path 10 that directly connects one end of the brake fluid path 10 to the second cylinder 82.

[0030] That is, the orifice 14 may be formed on the fluid introduction path 13 or on a section of the brake fluid path 10 that directly connects one end of the fluid introduction path 13 to the first cylinder 81 and / or the second cylinder 82. In this embodiment, one end of the fluid introduction path 13 is directly connected to the two first cylinders 81, but is not directly connected to the second cylinder 82.

[0031] Next, a method for manufacturing the brake caliper 1 of this embodiment will be described. In this embodiment, the brake caliper 1 is manufactured by the powder bed method. A laser beam or an electron beam is irradiated onto a spread metal powder to melt the metal powder and then solidify (or sinter). In particular, when a laser beam is used, this method is called the SLM (Selective Laser Melting) method or the SLS (Selective Laser Sintering) method. In this embodiment, the brake caliper 1 is printed in layers from below the state shown in FIG. 2 . However, after 3D printing, a cutting process is performed to smooth the bearing surface of the bracket 9, and minimal machining is performed to form the fastening threads of the bleeder bolt 11 and the brake piping at the open end of the fluid inlet path 13.

[0032] The powder bed method can achieve high molding accuracy, and therefore can suitably form the brake fluid path 10 that curves inside the brake caliper 1. In particular, it is suitable for forming the small cross-sectional area section 10X and the bleeder path 12, which have a small cross-sectional area.

[0033] During 3D printing, the first body 3 (including the bracket 9, etc.), the second body 4, the first bridge portion 5, and the second bridge portion 6 are integrally formed. In parallel with this integral formation, the brake fluid path 10 (including the small cross-sectional area section 10X and the orifice 14), the bleeder path 12, and the fluid introduction path 13 are also simultaneously formed within them. Because this is 3D printing, there is a high degree of freedom in the routing of these paths. Because the brake disc becomes hot due to frictional heat, it is desirable to place the brake fluid path 10 (small cross-sectional area section 10X) inside the first bridge portion 5 and the second bridge portion 6 that straddle the brake disc as far away from the brake disc as possible, even within the brake caliper 1. 3D printing makes this routing easy, preventing the brake fluid in the brake fluid path 10 from overheating.

[0034] In this embodiment, the powder bed method is used as the 3D printing method. However, other 3D printing methods, such as a metal deposition method, may also be used. In such a case, the brake fluid path 10 can be suitably formed inside the brake caliper 1. In particular, 3D printing is suitable for forming the small cross-sectional area section 10X and the bleeder path 12, which have a small cross-sectional area.

[0035] According to the manufacturing method of this embodiment, the first body 3, the second body 4, the first bridge portion 5, and the second bridge portion 6 are integrally formed from metal by 3D printing. While these components are formed, the brake fluid path 10 connecting the first cylinder 81 and the second cylinder 82 is also formed inside the brake caliper 1. As described above, if the brake fluid path is formed using an external pipe, there is a concern that air may enter through the fastening portion of the pipe. However, in this embodiment, the brake fluid path 10 is formed inside the brake caliper 1, so that air stagnation in the brake fluid path 10 can be effectively prevented.

[0036] Furthermore, as described above, 3D printing provides a high degree of freedom in routing the brake fluid path 10, and it is easy to form a curved brake fluid path 10. For example, when manufacturing a monoblock brake by casting, the core used to form the brake fluid path 10 becomes very thin. This raises concerns about narrowing of the brake fluid path 10. It is also difficult to remove the core from the brake fluid path 10 after casting. Because the degree of freedom in shaping the core is not high, the degree of freedom in routing the brake fluid path 10 is low.

[0037] When manufacturing a monoblock brake by casting or cutting, it is also conceivable to form the brake fluid path by drilling. In the cases of Patent Documents 1 and 2 mentioned above, it is thought that intersecting paths are formed by drilling. However, the brake fluid path formed by drilling is necessarily linear, and the degree of freedom in routing the brake fluid path 10 is low. Furthermore, drilling also requires blocking unnecessary portions of the formed path. This raises concerns about the infiltration of air or foreign matter through such blocked portions. The manufacturing method of this embodiment eliminates all such concerns.

[0038] According to the manufacturing method of this embodiment, when the brake fluid path 10 is formed, the small cross-sectional area section 10X and the bleeder path 12 are also formed. As described above, the small cross-sectional area section 10X and the bleeder path 12 have small cross-sectional areas, making it difficult to cast them using a core or to machine them using a thin drill. In other words, 3D printing can suitably form such small cross-sectional area section 10X and the bleeder path 12. Furthermore, the brake caliper 1 manufactured by the manufacturing method of this embodiment also provides the above-described advantages of the small cross-sectional area section 10X and the bleeder path 12.

[0039] Furthermore, according to the manufacturing method of this embodiment, it is also easy to form the brake fluid path 10 inside the second bridge portion 6 as an annular path. The brake caliper 1 manufactured by the manufacturing method of this embodiment also provides the above-mentioned advantages brought about by the brake fluid path 10 being an annular path.

[0040] Furthermore, according to the manufacturing method of this embodiment, it is easy to form the orifice 14 in the fluid introduction path 13 or in the section of the brake fluid path 10 that directly connects one end of the fluid introduction path 13 to the first cylinder 81 and / or the second cylinder 82. The brake caliper 1 manufactured by the manufacturing method of this embodiment also provides the above-mentioned advantages of the orifice 14.

[0041] 5 shows a brake caliper 1 according to the second embodiment. The difference between the brake caliper 1 of this embodiment and the brake caliper 1 of the first embodiment described above is that a chamber 15 for storing brake fluid is formed on the brake fluid path 10 formed inside the second bridge portion 6. The configuration other than the chamber 15 is the same as the configuration of the first embodiment, so a duplicated description thereof will be omitted.

[0042] The chamber 15 can hold a sufficient amount of brake fluid therein. As described above, the bleeder path 12 is disposed at a high position when the brake caliper 1 is mounted on a vehicle. The brake fluid path 10 is connected to the highest position of the chamber 15 in the brake caliper 1 mounted on a vehicle. By providing the chamber 15, the amount of brake fluid inside the brake caliper 1 can be increased.

[0043] During braking, the brake pads are pressed against the brake disc by the pistons housed in the first cylinder 81 and the second cylinder 82. At this time, surface wobble of the brake disc may cause pulsation in the hydraulic pressure of the brake fluid in the brake caliper 1. By increasing the amount of brake fluid, such pulsation can be suppressed, which in turn reduces hydraulic pressure fluctuations and wheel torque fluctuations, thereby suppressing judder vibration.

[0044] In this embodiment, the chamber 15 is provided on the brake fluid path 10 inside the second bridge portion 6, but it may be provided anywhere on the brake fluid path 10 other than the small cross-sectional area section 10X. However, by providing the chamber 15 inside the second bridge portion 6, the capacity of the chamber 15 can be increased, and the above-mentioned pulsation damping effect can be effectively obtained. Furthermore, when the chamber 15 is provided inside the second bridge portion 6, the chamber 15 is located between the first body 3 and the second body 4, so the above-mentioned pulsation generated in the first cylinder 81 and the second cylinder 82 can be effectively damped.

[0045] In this embodiment, as in the first embodiment, the brake caliper 1 is manufactured by 3D printing. The chamber 15 is also formed when the brake fluid path 10 is formed. It is impossible to form the chamber 15, which expands the internal space, in the middle of the brake fluid path 10 using drilling. While this is possible using casting with a core, casting with a core has the above-mentioned concerns. In other words, 3D printing makes it possible to preferably form the chamber 15 on the brake fluid path 10. Furthermore, the brake caliper 1 manufactured by the manufacturing method according to this embodiment also achieves the above-mentioned advantages provided by the chamber 15.

[0046] Figure 6 shows a cross-sectional view of a brake caliper 1 according to a third embodiment. This cross-section is taken along line VI-VI in Figure 2 (the brake caliper 1 in Figure 2 is the first embodiment). In the first embodiment, the brake fluid path 10 inside the second bridge portion 6 is formed linearly, as shown by the dotted line in Figure 6. In this embodiment, the brake fluid path 10 inside the second bridge portion 6 is curved so as to be separated from the brake disc, i.e., so as to be separated from the disc accommodating space 2.

[0047] In other words, the brake fluid path 10 formed inside the second bridge portion 6 is curved convexly radially outward from the brake disc (disc accommodating space 2). As a result, the brake fluid path 10 inside the second bridge portion 6 is positioned closer to the outer peripheral surface of the brake caliper 1 than to the inner peripheral surface of the disc accommodating space 2. The brake disc inside the disc accommodating space 2 generates heat due to friction during braking. By forming the brake fluid path 10 in this curved shape, the brake fluid in the brake fluid path 10 can be moved radially away from the brake disc, which is a heat source, thereby suppressing heat transfer to the brake fluid. By suppressing heat transfer to the brake fluid, vapor lock can be avoided.

[0048] In this embodiment, the brake fluid path 10 within the second bridge portion 6 is curved as described above. The brake fluid path 10 within the first bridge portion 5, i.e., the small cross-sectional area section 10X of the brake fluid path 10, may be curved in the same manner. In this case, too, heat transfer to the brake fluid within the brake fluid path 10 (small cross-sectional area section 10X) can be suppressed. However, when the small cross-sectional area section 10X is curved, the fluid introduction path 13 is connected to the apex of the curve.

[0049] In this embodiment, as in the first embodiment, the brake caliper 1 is manufactured by 3D printing. As described above, when the brake fluid path 10 is formed, it is curved convexly outward in the radial direction. It is impossible to form such a curved brake fluid path 10 by drilling. Although it is possible to do so by casting using a core, casting using a core has the above-mentioned concerns. In other words, 3D printing makes it possible to suitably form the curved brake fluid path 10 described above. Furthermore, the brake caliper 1 manufactured by the manufacturing method according to this embodiment also achieves the above-mentioned advantages brought about by the curved brake fluid path 10 described above.

[0050] 7 and 8 are a perspective view and a rear view, respectively, of a brake caliper 1 according to a fourth embodiment. In this embodiment, a plurality of heat dissipation fins 16 are formed on the outer surface of the first bridge portion 5 along the brake fluid path 10 (small cross-sectional area section 10X) formed inside the first bridge portion 5. In addition, a plurality of heat dissipation fins 16 are also formed on the outer surface of the second bridge portion 6 along the brake fluid path 10 formed inside the second bridge portion 6. The configuration other than the heat dissipation fins 16 is the same as the configuration of the first embodiment, so a duplicated description thereof will be omitted.

[0051] In this embodiment, the heat dissipation fins 16 are formed over a wide area, and are formed on almost the entire outer surfaces of the first bridge portion 5 and the second bridge portion 6. Furthermore, in this embodiment, the heat dissipation fins 16 are formed over an even wider area, and are also formed on part of the outer surface of the first main body 3 and part of the outer surface of the second main body 4.

[0052] As described above, the brake disc becomes hot due to frictional heat, and the brake fluid in the brake fluid path 10 (small cross-sectional area section 10X) inside the first bridge portion 5 and second bridge portion 6 that straddle the brake disc is easily affected by the heat. Therefore, by forming the heat dissipation fins 16 as in this embodiment to increase the surface area, it is possible to promote heat dissipation in the first bridge portion 5 and the second bridge portion 6. As a result, it is possible to prevent the temperature of the brake fluid in the brake fluid path 10 from rising.

[0053] In the present embodiment, the heat dissipation fins 16 are formed on the outer surfaces of the first bridge portion 5 and the second bridge portion 6. However, the heat dissipation fins 16 may be formed only on the outer surface of the first bridge portion 5. Alternatively, the heat dissipation fins 16 may be formed only on the outer surface of the second bridge portion 6. Furthermore, the heat dissipation fins 16 only need to be formed along the brake fluid path 10 formed inside the first bridge portion 5 (or the second bridge portion 6), and may be formed over a wider area as in the present embodiment.

[0054] In this embodiment, as in the first embodiment, the brake caliper 1 is manufactured by 3D printing. The heat dissipation fins 16 are integrally formed at the same time as printing the brake caliper 1. Although it is possible to form the heat dissipation fins 16 by cutting afterwards, this would increase the number of cutting steps. With 3D printing, it is relatively easy to form multiple heat dissipation fins 16 with complex shapes. With casting, it is difficult to fill a narrow space with molten metal, so it is difficult to form such heat dissipation fins 16. Furthermore, the brake caliper 1 manufactured by the manufacturing method according to this embodiment also achieves the above-mentioned advantages provided by the heat dissipation fins 16.

[0055] REFERENCE SIGNS LIST 1 Brake caliper 2 Disc accommodating space 3 First body 4 Second body 5 First bridge portion 6 Second bridge portion 81 First cylinder 82 Second cylinder 10 Brake fluid path 10X Small cross-sectional area section 11 Bleeder bolt 12 Bleeder path 13 Fluid introduction path 14 Orifice 15 Chamber 16 Heat dissipation fin

Claims

1. An opposed piston type monoblock brake caliper integrally formed from metal, a first body provided on one side of a disk housing space for housing a brake disk and having a first cylinder for housing a first piston; a second body having a second cylinder formed therein and accommodating a second piston opposed to the first piston, the second body being provided on the other side of the disk accommodating space; a first bridge portion provided at one end of the disk storage space and connecting the first body and the second body across the disk storage space; a second bridge portion provided on the other end side of the disk storage space and connecting the first body and the second body across the disk storage space; A brake fluid path formed inside the first body, the second body, and the first bridge portion so as to connect the first cylinder and the second cylinder; a bleeder passage formed inside the first bridge portion, one end of which is connected to the brake fluid passage and the other end of which is provided with a bleeder bolt, The bleeder path is connected to the brake fluid path inside the first bridge portion, a small cross-sectional area section that is in communication with the bleeder path and has a cross-sectional area smaller than a cross-sectional area of ​​other sections of the brake fluid path, an opposed-piston type monoblock brake caliper, wherein the brake fluid path formed inside the first bridge portion is curved convexly radially outwardly of the brake disc, spanning the disc accommodating space between the first body and the second body.

2. 2. The opposed piston type monoblock brake caliper according to claim 1, An opposed piston type monoblock brake caliper, wherein the brake fluid path is also formed inside the second bridge portion to form an annular path.

3. 3. The opposed piston type monoblock brake caliper according to claim 2, an opposed-piston type monoblock brake caliper, wherein the brake fluid path formed inside the second bridge portion is curved convexly radially outwardly of the brake disc, spanning the disc accommodating space between the first body and the second body.

4. 4. The opposed piston type monoblock brake caliper according to claim 2 or 3, An opposed-piston type monoblock brake caliper, wherein a plurality of heat dissipation fins are formed on an outer surface of the first bridge portion or the second bridge portion along the brake fluid path formed inside the first bridge portion or the second bridge portion.

5. An opposed piston type monoblock brake caliper according to any one of claims 1 to 3, an opposed piston type monoblock brake caliper, wherein a chamber for storing brake fluid is formed on the brake fluid path other than the small cross-sectional area section.

6. An opposed piston type monoblock brake caliper according to any one of claims 1 to 3, a brake fluid introduction passage having one end connected to the brake fluid passage and the other end connected to a brake pipe; an opposed-piston type monoblock brake caliper, wherein an orifice is formed in the fluid inlet path or in a section of the brake fluid path that directly connects the one end of the fluid inlet path to the first cylinder and / or the second cylinder.

7. A method for manufacturing an opposed piston type monoblock brake caliper, comprising the steps of: a first body provided on one side of a disk housing space for housing a brake disk and having a first cylinder formed therein for housing a first piston; a second body having a second cylinder formed therein and accommodating a second piston opposed to the first piston, the second body being provided on the other side of the disk accommodating space; a first bridge portion provided at one end of the disk storage space and connecting the first body and the second body across the disk storage space; a second bridge portion provided on the other end side of the disc accommodating space and connecting the first body and the second body across the disc accommodating space, A brake fluid path connecting the first cylinder and the second cylinder is formed inside the first body, the second body, and the first bridge portion, and the brake fluid path is integrally formed from metal by three-dimensional printing; A method for manufacturing an opposed-piston type monoblock brake caliper, wherein the brake fluid path formed inside the first bridge portion is curved convexly radially outward of the brake disc, spanning the disc accommodating space, between the first body and the second body.

8. A method for manufacturing the opposed piston type monoblock brake caliper according to claim 7, comprising the steps of: forming a bleeder passage inside the first bridge portion, the bleeder passage having one end connected to the brake fluid passage and the other end to which a bleeder bolt is attached, and forming the brake caliper integrally by three-dimensional printing; a small cross-sectional area section communicating with the bleeder path, the small cross-sectional area section being smaller than the cross-sectional area of ​​other sections of the brake fluid path in the first bridge portion.

9. A method for manufacturing an opposed piston type monoblock brake caliper according to claim 8, comprising the steps of: A method for manufacturing an opposed-piston monoblock brake caliper, comprising forming the brake caliper integrally by three-dimensional printing while forming the brake fluid path also inside the second bridge portion so that the brake fluid path forms a ring-shaped path.

10. A method for manufacturing an opposed piston type monoblock brake caliper according to claim 9, comprising the steps of: A method for manufacturing an opposed-piston type monoblock brake caliper, wherein the brake fluid path formed inside the second bridge portion is curved convexly radially outward of the brake disc, spanning the disc accommodating space between the first body and the second body.

11. A method for manufacturing an opposed piston type monoblock brake caliper according to claim 9 or 10, comprising the steps of: A manufacturing method for an opposed-piston type monoblock brake caliper, comprising forming a plurality of heat dissipation fins on an outer surface of the first bridge portion or the second bridge portion by three-dimensional printing along the brake fluid path formed inside the first bridge portion or the second bridge portion.

12. A method for manufacturing an opposed piston type monoblock brake caliper according to any one of claims 8 to 10, comprising the steps of: A method for manufacturing an opposed piston type monoblock brake caliper, wherein a chamber for storing brake fluid is formed on the brake fluid path other than the small cross-sectional area section.

13. A method for manufacturing an opposed piston type monoblock brake caliper according to any one of claims 7 to 10, comprising the steps of: a fluid introduction path having one end connected to the brake fluid path and the other end connected to a brake pipe is formed at the same time as the brake fluid path is formed; A method for manufacturing an opposed-piston type monoblock brake caliper, wherein an orifice is formed in the fluid inlet path or in a section of the brake fluid path that directly connects the one end of the fluid inlet path to the first cylinder and / or the second cylinder.