GB2555578A

GB2555578A - Hydraulic fluid ducts for disc brake calipers and method of manufacture thereof

Info

Publication number: GB2555578A
Application number: GB1618209.9A
Authority: GB
Inventors: Charles Smith Andrew; James Hodgkins Stephen; James Humble Richard
Original assignee: Alcon Components Ltd
Current assignee: Alcon Components Ltd
Priority date: 2016-10-27
Filing date: 2016-10-27
Publication date: 2018-05-09
Anticipated expiration: 2036-10-27
Also published as: GB201618209D0; GB2555578B

Abstract

A disc brake caliper body comprises a mounting side bracket 2 and a non-mounting side bracket 3 extending along a circumferential direction of the body with each bracket being configured to hold at least one brake pad. The caliper body further comprises at least one hydraulic fluid duct 6 formed by additive manufacturing. The hydraulic fluid duct comprises a side wall that extends continuously along a length of the duct. Where the side wall may be mathematically continuous in that it is differentiable at any point along its length resulting in improved, preferably laminar fluid flow. The duct may be an integral part of the caliper body and may be continuously curved when viewed in plan.

Description

(71) Applicant(s):

Alcon Components Limited (Incorporated in the United Kingdom)

Apollo, Lichfield Road Industrial Estate, TAMWORTH, Staffordshire, B79 7TN, United Kingdom (72) Inventor(s):

(56) Documents Cited:

EP 0907034 A2 WO 2013/105010 A1 US 20100320038 A1 JP H05293626

WO 2016/174426 A1 US 20150267812 A1 (58) Field of Search:

INT CL B33Y, F16D

Other: EPODOC, WPI, Patent Fulltext

Andrew Charles Smith Stephen James Hodgkins Richard James Humble (74) Agent and/or Address for Service:

Withers & Rogers LLP

More London Riverside, LONDON, SE1 2AU, United Kingdom (54) Title of the Invention: Hydraulic fluid ducts for disc brake calipers and method of manufacture thereof Abstract Title: Disc brake caliper comprising hydraulic fluid ducts (57) A disc brake caliper body comprises a mounting side bracket 2 and a non-mounting side bracket 3 extending along a circumferential direction of the body with each bracket being configured to hold at least one brake pad. The caliper body further comprises at least one hydraulic fluid duct 6 formed by additive manufacturing. The hydraulic fluid duct comprises a side wall that extends continuously along a length of the duct. Where the side wall may be mathematically continuous in that it is differentiable at any point along its length resulting in improved, preferably laminar fluid flow. The duct may be an integral part of the caliper body and may be continuously curved when viewed in plan.

Figure 1

1/5

Figure 1

2/5

Figure 3

3/5

Figure 4a

Figure 4b

4/5

101

104

111

102

107b

106c isss^jss-kssssi 1 11.....

l

120b

108c

Figure 5

108b

5/5

Figure 6a

314

Figure 6b

Hydraulic Fluid Ducts for Disc Brake Calipers and Method of Manufacture thereof

The present invention relates to a disc brake caliper body comprising at least one hydraulic fluid duct and a method of manufacture thereof. More specifically, the present invention is concerned with a disc brake caliper body comprising at least one hydraulic fluid duct formed by additive manufacturing.

Brake calipers are well known in the art. Such calipers are arranged to actuate a pair of opposed brake pads to clamp a brake disc therebetween. Clamping of the brake disc retards motion of a vehicle to which the caliper is attached. Brake calipers come in various forms. For example, pin-slider type calipers utilise a cylinder or cylinders on a single side of the disc to advance one of the two opposed pads. Once the pad is in contact with the disc, the caliper (which is slidably mounted for movement in the direction of actuation) slides such that the opposing pad also contacts the disc to clamp it between the pads. Opposed-piston type calipers, which are more common in motor sports, have a static caliper with two banks of cylinders, each of which advances a respective brake pad. As such, the caliper remains static but the disc is clamped between moving parts. In both cases, the general principle is the same - hydraulic pressure is increased in a cylinder to force two brake pads together to clamp a disc.

Known calipers comprise a brake caliper body which provides the strength and stiffness required to react to forces experienced under braking. The caliper body typically has two brackets, one either side of the plane of the brake disc, each bracket housing respective brake cylinders with associated pistons. Brake pads are mounted on a laterally inner face side of the caliper body for advancement towards the disc by pistons within the cylinders. The brackets are connected by one or more bridge members extending across, thereby straddling, the disc. Hydraulic fluid passages are attached to, and machined into, the caliper body to supply hydraulic fluid to the cylinders. For example, in a known brake caliper, an external hydraulic conduit is provided on the radial outer surface of one of bridge members spanning the caliper. The conduit is placed in fluid communication with a passage drilled into the bracket extending to the cylinder.

In other words, prior art solutions typically consist of two methods to transfer the hydraulic fluid within and around the caliper body: external hydraulic pipes and internal straight drillings. More recent inventions suggest casting a pipe into the caliper body. The stiffness of the caliper body is affected by the volume of hydraulic fluid present in the caliper as the fluid compresses. Straight drillings or cast features increase the hydraulic volume in the caliper body and hence reduce the stiffness of the caliper. Drillings are also limited to being straight and circular, which restricts their design freedom of the caliper and requires the caliper body generally to be larger as material is added to house the drillings of the hydraulic fluid ducts or enable bleeding of the latter. Extra material leads to higher weight caliper bodies, which are generally undesired particularly in racing applications. It is further a known problem that internal straight drillings require to be plugged at their intersection, rendering the manufacturing process more complicated and costly.

In view of the above, it is an object of the present invention to provide a disc brake caliper body with an improved hydraulic fluid duct, providing enhanced fluid transfer through the caliper. It is a further object of the invention to provide the improved hydraulic fluid transfer without comprising the structural integrity of the caliper body and at the same time reducing its weight.

According to a first embodiment, there is provided a disc brake caliper body comprising a mounting side bracket and a non-mounting side bracket extending along a circumferential direction of the body, each bracket being configured to hold at least one brake pad. The new disc brake caliper body further comprises at least one hydraulic fluid duct formed by additive manufacturing. The at least one hydraulic duct comprises a side wall extending continuously along a length of the hydraulic fluid duct.

As the skilled person will understand, the directions of a brake caliper are usually specified in relation to its brake disc. As such, the circumferential direction of the caliper is a direction parallel to the circumference of the rotor disc. The radial direction refers to a radial vector originating in the centre of the brake disc and could also be entitled as a direction from the bottom to the top of the brake caliper. Finally, the lateral direction of a brake caliper refers to the direction of the rotational axis of the brake disc. The lateral direction, therefore, extends perpendicular to the circumferential and radial direction.

By manufacturing the hydraulic fluid ducts in an additive manufacturing process, the ducts can essentially have any shape required for an optimised transfer of hydraulic fluid through the caliper. To this end, it is preferable to produce the entire caliper body by additive manufacturing. However, in some embodiments, only the hydraulic fluid duct may be produced by additive manufacturing, while other parts of the caliper may be formed by conventional machining steps. The additive layer manufactured hydraulic fluid duct can be arranged significantly closer to other functional parts of the caliper body (e.g. the cooling fluid ducts or cylinder housings) than conventionally known, machined hydraulic fluid ducts. The new caliper body requires significantly less machining and no drilling for production of the hydraulic ducts. As such, there is no more requirement for plug inserts to stop the hydraulic fluid from leaking out of the caliper body. The new cooling fluid ducts can be designed significantly shorter than known fluid ducts, and thus require much less material supporting the ducts, resulting in a lighter brake caliper design.

The term continuous in this specification refers to a mathematical meaning, namely that the side wall extends along a path that is differentiable at any point along the length of the hydraulic fluid duct. In simple terms, the side wall does not exhibit any sudden bends or comers. Rather, every point of the side wall extends smoothly along the length of the at least one hydraulic fluid duct. The continuous shape of the hydraulic fluid duct has the advantage that pressure losses within the duct are minimised.

In another embodiment, the at least one hydraulic fluid duct is an integral part of the brake caliper body. Accordingly, the hydraulic fluid duct may be manufactured at the same time as the remaining parts of the caliper body, reducing subsequent manufacturing steps and increasing the general structural integrity of the caliper body.

In another embodiment, the at least one hydraulic fluid duct has a continuously curved shape, when viewed in plan. The curved shape of the fluid duct prevents hydraulic fluid from being trapped in corners or dead ends of the duct, which is conventionally known to increase the resistance to the hydraulic fluid flow provided by the master cylinder. In other words, the hydraulic fluid duct of the present invention does not include sharp corners to avoid unnecessary resistance to the hydraulic fluid flow. Once again, the term continuously refers to a curvature that is differentiable at any point along the along the length of the hydraulic fluid duct. The shape of the hydraulic duct is defined by its side wall.

According to another aspect, the curved shape of the hydraulic fluid duct is arranged to bend such that a flow of hydraulic fluid is substantially laminar along the entire length of the hydraulic duct. It will be understood that sharp bends or even u-tums within the fluid duct will cause unintentional turbulences within the hydraulic fluid flow, which can reduce the activation speed of the brake pistons. The design of the hydraulic fluid duct is calculated such that turbulences are prevented at the corresponding fluid pressures applied to the caliper.

In another embodiment a cross-sectional shape of the hydraulic fluid duct varies along the length of the duct. In this embodiment it is generally feasible to maintain a cross-sectional flow area constant while the cross-sectional shape changes along the length of the hydraulic fluid duct. In one example, the cross section of the hydraulic fluid duct could change from a substantially circular cross-section to an oval or elliptical cross-section, depending on the surrounding parts of the caliper body. As such, the shape of the cross-section can be optimized to fit the shape of adjacent parts of the caliper body, such as cylinder housing portions and/or bridging members, as closely as possible.

According to another embodiment, a flow cross-sectional area of the hydraulic fluid varies along the length of the duct. The variable diameter or flow cross-sectional area of the hydraulic fluid duct can be used to individually control the fluid flow rate in different parts of the caliper body, for example, forcing one piston to advance quicker than another or helping to balance the fluid flow rates applied to the brake pistons in the mounting and non-mounting side brackets. In this regard, it should be understood that the fluid flow rates in conventional caliper bodies tend to be higher in the mounting side bracket, which is where the hydraulic fluid is usually first introduced into the caliper. In one embodiment, to balance this difference in flow rate between the mounting side and the non-mounting side bracket, the 4 fluid duct can comprise a generally larger cross-sectional flow area within the non-mounting side bracket than the flow area of ducts provided within the mounting side bracket. In some embodiments, the cross-sectional flow area and the cross-sectional shape of the at least one hydraulic duct change simultaneously.

In another embodiment, the mounting side and/or non-mounting side bracket comprises at least one cylinder housing portion and wherein the hydraulic fluid duct is shaped such that, in use, a flow of hydraulic fluid is accelerated or decelerated towards the cylinder housing portions. To this end, the hydraulic fluid duct may be constructed as a throttle (i.e. with a reduced flow area) at an entrance port of the cylinder housing portions, thereby ejecting the hydraulic fluid into the pressure chamber of each cylinder housing portion at a decreased speed). Alternatively, the flow area of the hydraulic fluid duct may be enlarged at an entrance port of the cylinder housing portion to increase fluid flow into the pressure chamber of the corresponding cylinder housing portion. The skilled person will appreciate that such a design can improve control over actuation speed of the brake caliper, facilitating a more balanced actuation of the mounting side and non-mounting side brake pistons.

According to another embodiment, the mounting side bracket and/or the non-mounting side bracket comprises at least two adjacent cylinder housings each adapted to receive a brake piston, the hydraulic fluid duct having a first port connecting to a rear section of a first cylinder housing and a second port connecting to a rear section of the adjacent second cylinder housing. The first and second port having a substantially oval cross-section. In simple terms, the hydraulic fluid duct connects the rear sections of adjacent cylinder housing portions, specifically at their rear section, i.e. their pressure chambers, which are arranged behind the brake pistons. The hydraulic fluid duct extending between the adjacent cylinder housing portions opens into the rear sections of the latter via first and second ports, which have a substantially oval cross-section. As will be described in more detail below, this oval cross-section allows for the pressure chambers of the cylinder housing portions to be reduced in size, resulting in further weight savings of the new caliper body.

According to another aspect, the hydraulic fluid duct extending between adjacent cylinder housing portions has a substantially reduced cross-sectional flow area between the first and second port. At the same time, the hydraulic fluid duct may change its cross-sectional shape between the first and second port from an oval shape to a substantially circular cross-section and back to an oval shape. This change in cross-sectional flow area can again act to decelerate the hydraulic fluid passing between adjacent cylinder housing portions and thus slightly slow the overall actuation speed of the caliper body down. Preferably, this particular embodiment is mainly incorporated between cylinder housing portions of the mounting side bracket.

In another embodiment, the brake caliper body comprises one or more bridging members connecting the mounting and non-mounting side bracket in a substantially lateral direction, wherein the hydraulic fluid duct extends at least partly through the one or more bridging members. According to this embodiment, the hydraulic fluid duct can be used to transfer the hydraulic fluid from the mounting side of the caliper body towards the non-mounting side bracket. The hydraulic fluid duct can extend through one or all of the bridging members depending on the flow rate required for the desired actuation speeds and the impact on stiffness of the caliper. At least the bridging member may be wholly produced by additive manufacturing.

In another embodiment, the one or more bridging members comprise a first end bridge arranged and configured to connect leading ends of the brackets and a second end bridge arranged and configured to connect trailing ends of the brackets, the hydraulic fluid duct extending at least partly through the first and/or end bridge. By transferring the hydraulic brake fluid directly through the leading and trailing end bridges, it is no longer necessary to provide an external fluid duct, which requires additional assembly steps and is prone to leakage. Leading and trailing end bridges are terms known to the skilled reader and refer to the direction of travel of the brake disc.

In another embodiment, the hydraulic fluid duct defines a cavity for conveying hydraulic fluid, the cavity comprising supplementary structures extending from an inner surface of the hydraulic fluid duct and wherein the structures are formed by additive manufacturing. The supplementary structures inside the hydraulic fluid duct can be provided along the entire length of the hydraulic duct or just in predetermined places. The supplementary structures can be used for a variety of different purposes, such as increasing the stiffness of the caliper body in predetermined areas or gradually splitting a single fluid duct into two or more fluid ducts. In the latter case, the supplementary structure may divide the cross-section of the fluid duct into two or more distinct parts, which can then be used to convey hydraulic fluid in two or more different directions, starting from a single hydraulic fluid duct.

According to another embodiment, at least parts of the supplementary structures comprise a lattice structure having a partial skin. In this application, the term skin is intended to mean as portion having a bulk density of substantially 100% of the material density from which it is formed. The term lattice structure is intended to mean a portion having a bulk density of 50% or less of material density from which it is formed. Advantageously, the lattice structure results in a strong, stiff, yet light design of the hydraulic fluid duct. The skin may be external or internal of the lattice structure. The lattice structure may be arranged in parts of the hydraulic fluid duct, which are subject to high bending stresses during use of the caliper body.

Preferably, the bulk density of 50% or less of the lattice structure is achieved by providing voids in the lattice structure of a volume greater than 50% of the cross-sectional area of the parts of the hydraulic fluid duct, which comprise the lattice structure. More preferably, the voids have a percentage void volume of at least 70%, in other words the bulk density of lattice structure is preferably 30% or less. Most preferably, the voids have a percentage void volume of 90%, corresponding to a lattice bulk density of 10%.

According to another embodiment, at least parts of the supplementary structures comprise a plurality of vanes. The vanes may extend straight along the length of the hydraulic fluid duct or in an undulating manner. Similar to the lattice structure described hereinbefore, the vanes can provide bending strength and stiffness to the hydraulic fluid duct and the caliper body in areas exposed to high bending stresses. The vanes may be used to support control of the flow rate of the hydraulic fluid within the caliper body.

Of course, it should be noted that the aforementioned supplementary structures within the hydraulic fluid duct are preferably only provided in certain areas, which either require improved stability or improved control of the fluid flow. It is feasible to have more than one structure within the hydraulic fluid duct, whereas other parts of the fluid duct may be completely free of the supplementary structures. Alternative structures include dendritic forms, high chrome structures, body centred cubic structures or gyroid structures. Preferably, any of such aforementioned structures are formed such that at least a minimum crosssectional area remains within the hydraulic fluid duct, which is required for the desired actuation speeds of the brake caliper.

In another embodiment, the caliper body comprises at least one cooling fluid duct formed by additive manufacturing. Similar to the hydraulic fluid duct, the cooling fluid duct formed by additive manufacturing can essentially have any shape desired and preferably has a continuously curved shape when viewed in plan. The at least one cooling fluid duct can be an integral part of the brake caliper body or a separately removable part. The new cooling fluid duct also does not require straight drillings or plug inserts and can be arranged closely to the functional parts of the caliper body, thereby increasing the cooling efficiency.

In another embodiment, the curved shape of the cooling fluid duct is adapted to bend such that a flow of cooling fluid is substantially laminar along the entire length of the cooling fluid duct. In other embodiments, the cooling fluid duct may be shaped to introduce local turbulances in pre-determined areas, for example areas in which the cooling fluid should remain longer to absorb more heat.

According to another aspect, the flow cross-sectional area of the cooling fluid duct varies along the length of the duct. It will be understood that this can again be used to control the flow rate of the cooling fluid along the duct, to establish areas within the duct in which more heat is absorbed by the cooling fluid, i.e. in the vicinity of the cylinder housing portions.

In another embodiment, the at least parts of the cooling fluid duct are arranged coaxially with the at least one hydraulic fluid duct. In this embodiment, the cooling fluid duct may have a similar shape to the hydraulic fluid duct, that is, if the hydraulic fluid duct has an oval shape, the cooling fluid duct may have the same oval shape with a larger diameter. The cooling fluid duct of this embodiment can be used to actively control the temperature of the hydraulic fluid within the caliper. The skilled person will understand that this will help in maintaining constant functionality of the hydraulic brake caliper.

The cooling fluid duct can surround at least parts the hydraulic fluid duct, in which case the hydraulic fluid duct is constructed as a tube running inside the cooling fluid duct. The cooling fluid duct being separated from the hydraulic fluid duct by material of the caliper body. The cooling fluid duct may be constructed as a hollow cavity or, similar to the hydraulic fluid duct, with a plurality of supporting members. As such, the cooling fluid duct may comprise supplementary structures in the form of a lattice structure, vanes or column shaped reinforcement ribs. In a particular example, the cooling fluid duct may be constructed as a lattice structure surrounding the hydraulic fluid duct, the voids of the lattice structure being used to conduct the cooling fluid.

In another embodiment, the mounting side and/or non-mounting side bracket comprises at least one cylinder housing portion, the cooling fluid duct extending around at least parts of a circumference of the cylinder housing portions. In this embodiment, parts of the cooling duct surrounding the cylinder housing portions may be constructed as a cooling jacket, enclosing at least parts of the cylinder housing portions. In one embodiment, the cooling fluid duct extends around at least a seal groove of the cylinder housing portions. In other words, the cooling fluid duct may at least extend around a front part of the cylinder housing portions to protect the piston seals from overheating. In other embodiments, the cooling fluid duct may only extend around parts of the circumference of the respective cylinder housing portions.

That is, the cooling fluid duct may cover less than 360 degrees the cylinder housing circumference, such as half the circumference or 180 degrees, etc.

According to another embodiment, the cooling fluid duct defines a cavity for conveying cooling fluid, the cavity comprising supplementary structures extending from an inner surface of the cooling fluid duct and wherein the structures are formed by additive manufacturing. The supplementary structures inside the cooling fluid duct can be provided along the entire length of the cooling fluid duct or just in predetermined places. The supplementary structures can be used for a variety of different purposes, such as increasing the stiffness of the caliper body in predetermined areas or increasing the surface area contacted by cooling fluid running through cooling fluid duct.

The supplementary structures inside the cooling fluid duct can once again have any desired shape or form, such as the lattice and vane structures described hereinbefore with reference to the hydraulic fluid duct.

The present invention further relates to a method of forming a brake caliper body, the method comprising constructing the caliper body layer by layer, according to a digital record of a caliper body with a hydraulic fluid duct. In another embodiment, the digital record of the caliper body may include a hydraulic fluid duct and a cooling fluid duct. The digital record of the caliper body may be created using an FE simulation of the brake caliper body. The hydraulic fluid duct and/or cooling fluid duct may be provided in low stress areas of the caliper body simulated by the FE simulation. Alternatively or additionally, a lattice structure, vanes or reinforcement members can be provided within the hydraulic fluid duct and/or the cooling fluid duct in areas of high stress.

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings. The drawings show:

FIGURE 1 is a blank view of an embodiment of the caliper body according to the present invention;

FIGURE 2 is a perspective cross-section along line A-A in Figure 1;

FIGURE 3 is a partial cross-section of a mounting side bracket of a caliper body according to another embodiment of the present invention;

FIGURE 4a is a vertical cross-section through a cylinder housing portion of a caliper body according to another embodiment of the present invention;

FIGURE 4b shows a cross-section of adjacent cylinder housing portions shown in Figure 4a;

FIGURE 5 is a plan view of half a caliper body according to another embodiment of the present invention; and

FIGURE 6a is a schematic cross-section through a hydraulic fluid duct and a cooling fluid duct according to another embodiment of the present invention.

FIGURE 6b is a schematic cross-section through a hydraulic fluid duct and a cooling fluid duct according to another embodiment of the present invention.

Figure 1 shows a top plan view of a caliper body 1 comprising a mounting side bracket 2 and a non-mounting side bracket 3. In this embodiment, the mounting side bracket 2 is connected to the non-mounting side bracket 3 via bridging members 4, 5 and 9 which extend in a lateral direction Y between the mounting side and non-mounting side brackets 2 and 3. A first bridging member 4 extends at a leading end of the caliper body 1 and forms a leading end bridge. A second bridging member 5 extends at an opposite, trailing end of the caliper body 1 and forms a tailing end bridge. A third bridging member 9 is arranged between the first and second end bridges 4, 5 and separated from them by radial openings 41, 42.

The mounting side bracket 2 comprises three cylinder housing portions 7a, 7b and 7c. The cylinder housing portions 7a, 7b, 7c are arranged in series, that is adjacent to each other, in a circumferential direction X of the caliper body 1. The non-mounting side bracket 3 also comprises three cylinder housing portions 8a, 8b and 8c. The cylinder housing portions 8a, 8b and 8c are arranged next to each other in a circumferential direction X of the caliper body 1.

A plurality of hydraulic fluid ducts 6a, 6b, 6c, 6d and 6e are provided within the caliper body 1 by additive manufacturing. The hydraulic fluid ducts 6a to 6e are adapted to provide each of the cylinder housings 7a, 7b, 7c, 8a, 8b and 8c with hydraulic fluid, which is conventionally introduced into a rear part of each corresponding cylinder housing portion 7a to 8c. Accordingly, the hydraulic fluid ducts 6a, 6b, 6c, 6d and 6e are conventionally attached to the respective cylinder housing portions 7a to 8c at a rear section thereof. Hydraulic fluid ducts 6a, 6b, 6d and 6e are adapted to connect adjacent cylinder housing portions with each other. In contrast to this, the hydraulic fluid duct 6c connects cylinder housing portion 7c of the mounting side bracket 2 with the cylinder housing portion 8c of the non-mounting side bracket 3. As such, the hydraulic fluid duct 6c extends through the trailing end bridge 5 and extends in a substantially lateral direction between the nonmounting side bracket 3 and the mounting side bracket 2.

As will be described in more detail below, each of the hydraulic fluid ducts 6a to 6e has a side wall that extends continuously along the length of the respective fluid duct 6a to 6e. That is, the side wall extend along a mathematical path that is differentiable at any paint along the length of the hydraulic fluid duct.

The hydraulic fluid ducts 6a to 6e are also connected to an inlet port 21, which is preferably arranged along the mounting side bracket 2, although it will be understood that it is equally possible to arrange the inlet port 21 along the non-mounting side bracket 3 or along both side brackets 2, 3 instead. In the illustrated embodiment, the inlet port is directly connected to the central cylinder housing portion 7b of the mounting side bracket 2, however the inlet port could be arranged along the leading or trailing cylinder housing portions 7a or 7c respectively, instead. Hydraulic fluid entering the caliper body 1 from the master cylinder (not shown) via inlet port 21, will be conveyed to the other cylinder housing portions by means of the hydraulic fluid ducts 6a to 6e. Fig. 1 further shows to exemplary bleed ports 22, 32, one at the leading end of the mounting side bracket 2 and the other at a leading end of the non-mounting side bracket 3.

From the plan view of Figure 1, it is derivable that at least hydraulic fluid duct 6c has a continuously curved shape, which provides for improved, preferably laminar flow between the cylinder housing portion 7c and 8c. In contrast to this, prior art solutions implement straight hydraulic ducts with several sharp comers, which impede the fluid flow.

The hydraulic fluid duct 6c shown in Figure 1 also has a varying cross-sectional flow area between the cylinder housing portion 7c and 8c. In particular, and by way of example only, the cross-sectional flow area of the hydraulic fluid duct 6c is smaller at its end portions (where the hydraulic fluid duct 6c connects with the cylinder housing portions 7c and 8c respectively). Between these two sections, the cross-sectional flow area of the hydraulic fluid conduit 6c is increased, thereby providing a shape in which hydraulic fluid flowing through duct 6c from the mounting side bracket cylinder housing portion 7c can be accelerated towards the non-mounting side cylinder housing portion 8c.

The hydraulic fluid duct of the present invention can essentially have any shape required for optimal fluid flow between the cylinder housing portions and an inlet port of caliper body 1, for as long as the side wall extends continuously throughout. In the embodiment of Figure 1, the side wall 65c of the hydraulic fluid duct 6c has an oval cross-section, as can be derived from Figure 2. The oval shaped duct can be arranged such that the longer diameter of the duct 6c is aligned with the circumferential direction X of the caliper body 1. As a consequence, the shorter diameter of the hydraulic fluid duct 6c is aligned with the radial direction set of the caliper body 1, thereby enabling the trailing end bridge 5 to be substantially reduced in thickness. As mentioned earlier, the cross-sectional shape of the hydraulic fluid ducts may vary along the length of the duct, with or without changing the cross-sectional flow area of the duct.

Figure 2 further shows an inlet port 61 of hydraulic fluid conduit 6b within cylinder housing portion 8c, which will be described in more detail with reference to Figures 4a and 4b below.

Figure 3 shows another embodiment of a caliper body according to the present invention. In the embodiment shown in Figure 3, a hydraulic fluid duct 6c' is shown which has substantially straight sections connected by a gradually curved comer portion. While not all portions of the hydraulic fluid duct 6c' are curved, it should be noted that the duct 6c' is a unitary stmcture in which all of the straight and curved parts are produced at the same time, that is by additive manufacturing. The straight and curved parts of the duct 6c' extend continuously, that is side wall 65c' is differentiable at any point along its length. As will be described in more detail with reference to Figure 5 below, a cooling jacket 120a' may be formed at least partly around the circumference of one or more of the cylinder housing portions 8c'. The cooling jacket 120a' is part of a cooling fluid duct, which is also formed by additive manufacturing, an example of which is shown in Figure 5.

As mentioned previously, adjacent cylinder housing portions 7a to 8c are interconnected by hydraulic fluid ducts 6a, 6b, 6d and 6e along their rear end portions. One embodiment of such a hydraulic fluid duct 6a' between the cylinder housing portions 8a' and 8b' is illustrated in Figures 4a and 4b. The hydraulic fluid duct 6a' has a first port 61 connecting the hydraulic fluid duct 6a' with the cylinder housing portion 8b' and a second fluid port 62, connecting the hydraulic fluid duct 6a' with the adjacent cylinder housing portion 8a'. While it is conventionally known to connect hydraulic fluid ducts with the rear part of the cylinder housing portions, Figure 4a shows that port 61 (and preferably also port 62) has an oval shape. The longer diameter of the oval shaped first port 61 is aligned with the circumference of the cylinder housing portion 8b, that is in a radial direction of the caliper body 1, while the shorter diameter of the oval shaped port 61 is arranged along the lateral direction Y of the caliper body 1. As such, the hydraulic fluid conduit 6a' can be connected to the circumferential side wall of the cylinder housing portion 8b', without extending too far into the cylinder housing portion along the lateral direction Y of the caliper body. As a consequence, the cylinder housing portions 7a to 8c of the present caliper body can be constructed in a more compact manner and fluid introduced into the pressure chamber behind the brake piston will act more effectively on a back surface of the respective piston.

As indicated by Figure 4b, the second port 62 of the hydraulic fluid conduit 6a' extending into the adjacent cylinder housing portion 8a' also has an oval shaped cross-section. In order to 14 optimise hydraulic fluid flow between the first port 61 and the second port 62 of the hydraulic fluid duct 6a'. A central portion 63 connecting the first fluid port 61 to the second fluid port 62 may have a different cross-sectional flow area and/or shape, such as a reduced crosssectional flow are with substantially circular cross-sectional shape. In other words, even the hydraulic fluid ducts 6a, 6b, 6d and 6e can have a varying cross-section along their length. The reduced cross-sectional flow area of the central portion 63 effectively acts as a throttle between the adjacent cylinder housing portions 8a', 8b'. Hydraulic fluid ducts with a reduced cross-sectional flow area may advantageously be implemented between cylinder housing portions of the mounting side bracket, too slow down actuation of the mounting side brake pistons. Hydraulic fluid ports on the non-mounting side, however, may have a central portion with an increased cross-sectional flow area, thereby improving fluid flow between adjacent cylinder housing portions, resulting in higher actuation speeds of the non-mounting side brake pistons. In this way, the shape and size of the hydraulic fluid ducts 6a to 6e may be varied to balance actuation speed between the mounting side and non-mounting side brackets.

A bottom plan view of a caliper body according to another embodiment of the present invention is shown in Figure 5. Functionally identical parts of the embodiments in Figures 1 and 5 are labelled with identical reference signs increased by 100. As shown, a hydraulic fluid conduit 106c is provided to connect the rear parts of cylinder housing portions 107c and 108c. Similar to the hydraulic fluid duct 6c in Figure 1, the hydraulic fluid duct 106c has a continuously curved shape to provide substantially only laminar flow of hydraulic fluid between the cylinder housing portions 107c and 108c.

In addition to the hydraulic fluid duct 106c, a cooling fluid duct 110 is provided. The cooling fluid duct extends in a continuously curved shape from a cooling fluid inlet port 111. The cooling fluid inlet port 111 is arranged on the mounting side bracket 102 of the caliper body

101. The cooling fluid duct 110 extends from the inlet port 111 towards one of the cylinder housing portions 107c on the mounting side bracket 102 of the caliper body and to one of the non-mounting side cylinder housing portions 108c. As such, the cooling fluid duct 110 extends in a substantially lateral direction Y of the caliper body, through the leading end bridge 104. As can be seen, the cooling fluid duct 110 extends close to and is interwoven with the hydraulic fluid duct 106c between the cylinder housing portions 107c and 108c. At 15 the cylinder housing portions 107c, the cooling fluid duct 110 forms a cooling jacket 120a on the mounting side bracket 2 and a cooling jacket 120b on the non-mounting side bracket 103. As shown, the cooling jackets 120a and 120b do not cover the entire length (lateral direction Y) of their respective cylinder housing portions 107c, 108c, but do surround the cylinder housing portions 107c and 108c at least at seal grooves at a front part of the cylinder housing portions. The cooling fluid duct 110 can be adapted to conduct any fluids, such as gas or liquid. In one embodiment, the fluid conducted by the cooling fluid duct 110 is cooling water, which is provided to the caliper body via inlet port 111.

An alternative embodiment is shown in Figure 6a. In this embodiment, a schematic crosssection of one variant of the hydraulic fluid and cooling fluid ducts is shown. In this embodiment, a hydraulic fluid duct 206 is surrounded by cooling fluid duct 210. The cooling fluid duct 210 is separated from the hydraulic fluid duct 206 by a portion 212 of the caliper body. The shape of the cooling fluid duct 210 is defined by another portion of the caliper body surrounding the cooling fluid duct 210. This construction is obtained by forming a unitary structure of the caliper body and the cooling and hydraulic fluid ducts 206, 210 during additive manufacturing. In the embodiment of Figure 6a, the hydraulic fluid duct 206 and the cooling fluid duct 210 are formed as empty cavities. However, it is equally feasible to provide internal support structures within the hydraulic fluid duct and/or the cooling fluid duct, as can be derived from Figure 6b.

Figure 6b shows an embodiment of the hydraulic fluid duct and cooling fluid ducts shown in Figure 6a, in which supplementary structures in the form of vanes 307 and 311 are provided within the cavities of the hydraulic fluid duct 306 and the cooling fluid duct 310 respectively. The vanes 307 and/or 311 can extend in any desired direction. While undulating vanes 311 within the cooling fluid duct 310 effectively increase the surface area contacted by the cooling fluid running within the cooling fluid duct 310, vane 307 separates hydraulic fluid duct 306 into two distinct ducts 306a, 306b. Furthermore, it should be appreciated that the supplementary structures such as the vanes 307 and 311 can have any other shape or form, such as straight/undulating vanes or a lattice structure, for example.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out the preceding paragraphs, in the claims and/or in the detailed description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

Claims

1. A disc brake caliper body comprising:

• a mounting side bracket and a non-mounting side bracket extending along a circumferential direction of the body, each bracket being configured to hold at least one brake pad, and • at least one hydraulic fluid duct formed by additive manufacturing, the at least one hydraulic duct comprising a side wall extending continuously along a length of the hydraulic fluid duct.

2. The disc brake caliper body of claim 1, wherein the at least one hydraulic fluid duct is an integral part of the brake caliper body.

3 .The disc brake caliper body of claim 1 or 2, wherein the at least one hydraulic fluid duct has a continuously curved shape, when viewed in plan.

4. The disc brake caliper body of claim 3, wherein the continuously curved shape of the hydraulic fluid duct is arranged to bend such that a flow of hydraulic fluid is substantially laminar along the entire length of the hydraulic duct.

5. The disc brake caliper body of any of claims 1 to 4, wherein a cross-sectional shape of the hydraulic fluid duct varies along the length of the duct.

6. The disc brake caliper body of any of claims 1 to 5, wherein a cross-sectional flow area of the hydraulic fluid duct varies along the length of the duct.

7. The disc brake caliper body of any of claims 6, wherein the mounting side and/or nonmounting side bracket comprises at least one cylinder housing portion and wherein the hydraulic fluid duct is shaped such that, in use, a flow of hydraulic fluid is accelerated or decelerated towards the cylinder housing portions.

8. The disc brake caliper body of any of claims 1 to 7, wherein the mounting side bracket and/or the non-mounting side bracket comprises at least two adjacent cylinder housing 18 portions each adapted to receive a brake piston, the hydraulic fluid duct having a first port connecting to a rear section of a first cylinder housing portions and a second port connecting to the a rear section of the adjacent cylinder housing portion, the first and second port having a substantially oval cross-section.

9. The disc brake caliper body of claim 8, wherein hydraulic fluid duct has a substantially circular cross-section between the first and second port.

10. The disc brake caliper body of any of claims 1 to 9, wherein the brake caliper body comprises one or more bridging members connecting the mounting and non-mounting side brackets in a substantially lateral direction, wherein the hydraulic fluid duct extends at least partly through the one or more bridging members.

11. The disc brake caliper body of claim 10, wherein the one or more bridging members comprise a first end bridge arranged and configured to connect leading ends of the brackets and a second end bridge arranged and configured to connect trailing ends of the brackets, the hydraulic fluid duct extending at least partly through the first and/or second end bridge.

12. The disc brake caliper body of any of claims 1 to 11, wherein the hydraulic fluid duct defines a cavity for conveying hydraulic fluid, the cavity comprising supplementary structures extending from an inner surface of the hydraulic fluid duct, and wherein the structures are formed by additive manufacturing.

13. The disc brake caliper body of claim 12, wherein the supplementary structures are adapted to increase stiffness, at least in predetermined areas of the caliper body.

14. The disc brake caliper body of claim 12 or 13, wherein at least parts of the supplementary structures comprise a lattice structure having a partial skin.

15. The disc brake caliper body of claim 14, wherein the lattice structure has a density of 10% to 50%, more preferably 10% to 30%.

16. The disc brake caliper body of any of claims 12 to 15, wherein at least parts of the supplementary structures comprise a plurality of vanes.

17. The disc brake caliper body of claim 16, wherein the vanes extend straight along the length of the hydraulic fluid duct.

18. The disc brake caliper body of claim 17, wherein the vanes extend in an undulating manner along the length of the hydraulic fluid duct.

19. The disc brake caliper body of any of claims 1 to 18, wherein caliper body comprises at least one cooling fluid duct formed by additive manufacturing.

20. The disc brake caliper body of claim 19, wherein the at least one cooling fluid duct is an integral part of the brake caliper body.

21. The disc brake caliper body of claim 19 or 20, wherein the at least one cooling fluid duct has a continuously curved shape, when viewed in plan.

22. The disc brake caliper body of claim 21, wherein the a continuously curved shape of the cooling fluid duct is adapted to bend such that a flow of cooling fluid is laminar along the entire length of the cooling fluid duct.

23. The disc brake caliper body of any of claims 19 to 22, wherein a flow cross-sectional area of the cooling fluid duct varies along the length of the duct.

24. The disc brake caliper body of any of claims 23, wherein the mounting side and/or nonmounting side bracket comprises at least one cylinder housing portion, and wherein the cooling fluid duct is shaped such that, in use, a flow of cooling fluid is accelerated towards the cylinder housing portion.

25. The disc brake caliper body of any of claims 19 to 24, wherein at least parts of the cooling fluid duct are arranged coaxially with the at least one hydraulic fluid duct.

26. The disc brake caliper body of claim 25, wherein the cooling fluid duct surrounds at least parts of the hydraulic fluid duct.

27. The disc brake caliper body of any of claims 19 to 26, wherein the brake caliper body comprises one or more bridging members connecting the mounting and non-mounting side brackets in a substantially lateral direction, wherein the cooling fluid duct extends at least partly through the one or more bridging members.

28. The disc brake caliper body of claim 27, wherein the one or more bridging members comprise a first end bridge arranged and configured to connect leading ends of the brackets and a second end bridge arranged and configured to connect trailing ends of the brackets, the cooling fluid duct extending at least partly through the first and/or second end bridge.

29. The disc brake caliper body of any of claims 19 to 28, wherein the mounting side and/or non-mounting side bracket comprises at least one cylinder housing portion, the cooling fluid duct extending around at least parts of a circumference of the cylinder housing portions.

30. The disc brake caliper body of claim 29, wherein the cooling fluid duct extends around at least parts of a seal groove of the cylinder housing portions.

31. The disc brake caliper body of any of claims 19 to 30, wherein the cooling fluid duct defines a cavity for conveying hydraulic fluid, at least parts of the cavity comprising supplementary structures extending from an inner surface of the cooling fluid duct, and wherein the structures are formed by additive manufacturing.

32. The disc brake caliper body of claim 31, wherein the supplementary structures are adapted to increase stiffness and/or increase the surface area contacted by the cooling fluid, at least in predetermined areas of the caliper body.

33. The disc brake caliper body of claim 31 or 32, wherein at least parts of the supplementary structures comprise a lattice structure having a partial skin.

34. The disc brake caliper body of any of claims 31 to 33, wherein at least parts of the 5 supplementary structures comprise a plurality of vanes.

35. The disc brake caliper body of claim 34, wherein the vanes extend straight along the length of the hydraulic fluid duct.

10 36.The disc brake caliper body of claim 35, wherein the vanes extend in an undulating manner along the length of the hydraulic fluid duct.

37. A method of forming a brake caliper body, said method comprising constructing the caliper body layer by layer, according to a digital record of a caliper body with a hydraulic fluid

15 duct.

38. The method of claim 37, wherein the digital record of the caliper body is created using an FE simulation of the brake caliper body.

20 39.The method of claim 38, wherein the method includes providing the hydraulic fluid duct in low stress areas of the caliper body simulated by the FE simulation.

40.The method of any of claims 37 to 39, wherein the method includes providing a lattice structure, vanes or reinforcement members within the hydraulic fluid duct in areas of high

25 stress.

Amendments to the claims have been filed as follows:

06 10 17

1. A disc brake caliper body comprising:

• a mounting side bracket and a non-mounting side bracket extending along a

5 circumferential direction of the body, each bracket being configured to hold at least one brake pad, and • at least one hydraulic fluid duct formed by additive manufacturing, the at least one hydraulic duct comprising a side wall extending continuously along a length of the hydraulic fluid duct, wherein the hydraulic fluid duct defines a cavity for conveying

10 hydraulic fluid, the cavity comprising supplementary structures extending from an inner surface of the hydraulic fluid duct, and wherein the structures are formed by additive manufacturing.

2. The disc brake caliper body of claim 1, wherein the at least one hydraulic fluid duct is an

15 integral part of the brake caliper body.

3. The disc brake caliper body of claim 1 or 2, wherein the at least one hydraulic fluid duct has a continuously curved shape, when viewed in plan.

20 4.The disc brake caliper body of claim 3, wherein the continuously curved shape of the hydraulic fluid duct is arranged to bend such that a flow of hydraulic fluid is substantially laminar along the entire length of the hydraulic duct.

5. The disc brake caliper body of any of claims 1 to 4, wherein a cross-sectional shape of the

25 hydraulic fluid duct varies along the length of the duct.

30 7.The disc brake caliper body of any of claims 6, wherein the mounting side and/or nonmounting side bracket comprises at least one cylinder housing portion and wherein the hydraulic fluid duct is shaped such that, in use, a flow of hydraulic fluid is accelerated or decelerated towards the cylinder housing portions.

8. The disc brake caliper body of any of claims 1 to 7, wherein the mounting side bracket and/or the non-mounting side bracket comprises at least two adjacent cylinder housing portions each adapted to receive a brake piston, the hydraulic fluid duct having a first port

5 connecting to a rear section of a first cylinder housing portions and a second port connecting to the a rear section of the adjacent cylinder housing portion, the first and second port having a substantially oval cross-section.

9. The disc brake caliper body of claim 8, wherein hydraulic fluid duct has a substantially

10 circular cross-section between the first and second port.

lO.The disc brake caliper body of any of claims 1 to 9, wherein the brake caliper body comprises one or more bridging members connecting the mounting and non-mounting side brackets in a substantially lateral direction, wherein the hydraulic fluid duct extends at

15 least partly through the one or more bridging members.

11.The disc brake caliper body of claim 10, wherein the one or more bridging members comprise a first end bridge arranged and configured to connect leading ends of the brackets and a second end bridge arranged and configured to connect trailing ends of the brackets, the hydraulic fluid duct extending at least partly through the first and/or second end bridge.

12. The disc brake caliper body of any of claims 1 to 11, wherein the supplementary structures are adapted to increase stiffness, at least in predetermined areas of the caliper body.

13. The disc brake caliper body of any of claims 1 to 12, wherein at least parts of the supplementary structures comprise a lattice structure having a partial skin.

14. The disc brake caliper body of claim 13, wherein the lattice structure has a density of 10% 30 to 50%, more preferably 10% to 30%.

15.The disc brake caliper body of any of claims 1 to 14, wherein at least parts of the supplementary structures comprise a plurality of vanes.

16.The disc brake caliper body of claim 15, wherein the vanes extend straight along the length of the hydraulic fluid duct.

5 17.The disc brake caliper body of claim 16, wherein the vanes extend in an undulating manner along the length of the hydraulic fluid duct.

18. The disc brake caliper body of any of claims 1 to 17, wherein caliper body comprises at least one cooling fluid duct formed by additive manufacturing.

19. The disc brake caliper body of claim 18, wherein the at least one cooling fluid duct is an integral part of the brake caliper body.

2O.The disc brake caliper body of claim 18 or 19, wherein the at least one cooling fluid duct 15 has a continuously curved shape, when viewed in plan.

21. The disc brake caliper body of claim 20, wherein the a continuously curved shape of the cooling fluid duct is adapted to bend such that a flow of cooling fluid is laminar along the entire length of the cooling fluid duct.

22. The disc brake caliper body of any of claims 18 to 21, wherein a flow cross-sectional area of the cooling fluid duct varies along the length of the duct.

23. The disc brake caliper body of any of claims 22, wherein the mounting side and/or non25 mounting side bracket comprises at least one cylinder housing portion, and wherein the cooling fluid duct is shaped such that, in use, a flow of cooling fluid is accelerated towards the cylinder housing portion.

24. The disc brake caliper body of any of claims 18 to 23, wherein at least parts of the cooling 30 fluid duct are arranged coaxially with the at least one hydraulic fluid duct.

25. The disc brake caliper body of claim 24, wherein the cooling fluid duct surrounds at least parts of the hydraulic fluid duct.

26. The disc brake caliper body of any of claims 18 to 25, wherein the brake caliper body 5 comprises one or more bridging members connecting the mounting and non-mounting side brackets in a substantially lateral direction, wherein the cooling fluid duct extends at least partly through the one or more bridging members.

27. The disc brake caliper body of claim 26, wherein the one or more bridging members 10 comprise a first end bridge arranged and configured to connect leading ends of the brackets and a second end bridge arranged and configured to connect trailing ends of the brackets, the cooling fluid duct extending at least partly through the first and/or second end bridge.

28.The disc brake caliper body of any of claims 18 to 27, wherein the mounting side and/or non-mounting side bracket comprises at least one cylinder housing portion, the cooling fluid duct extending around at least parts of a circumference of the cylinder housing portions.

CO

120 29.The disc brake caliper body of claim 28, wherein the cooling fluid duct extends around at least parts of a seal groove of the cylinder housing portions.

30.The disc brake caliper body of any of claims 18 to 29, wherein the cooling fluid duct defines a cavity for conveying hydraulic fluid, at least parts of the cavity comprising

25 supplementary structures extending from an inner surface of the cooling fluid duct, and wherein the structures are formed by additive manufacturing.

31.The disc brake caliper body of claim 30, wherein the supplementary structures are adapted to increase stiffness and/or increase the surface area contacted by the cooling fluid, at least

30 in predetermined areas of the caliper body.

32.The disc brake caliper body of claim 30 or 31, wherein at least parts of the supplementary structures comprise a lattice structure having a partial skin.

06 10 17

33.The disc brake caliper body of any of claims 30 to 32, wherein at least parts of the supplementary structures comprise a plurality of vanes.

5 34.The disc brake caliper body of claim 33, wherein the vanes extend straight along the length of the hydraulic fluid duct.

35. The disc brake caliper body of claim 34, wherein the vanes extend in an undulating manner along the length of the hydraulic fluid duct.

36. A method of forming a brake caliper body, said method comprising constructing the caliper body layer by layer, according to a digital record of a caliper body with a hydraulic fluid duct.

15

37.The method of claim 36, wherein the digital record of the caliper body is created using an FE simulation of the brake caliper body.

38. The method of claim 37, wherein the method includes providing the hydraulic fluid duct in low stress areas of the caliper body simulated by the FE simulation.

39. The method of any of claims 36 to 38, wherein the method includes providing a lattice structure, vanes or reinforcement members within the hydraulic fluid duct in areas of high stress.

Intellectual

Property

Office

Application No: Claims searched:

GB1618209.9

1-40