GB2548632A

GB2548632A - Lightweight disc brake caliper body

Info

Publication number: GB2548632A
Application number: GB1605145.0A
Authority: GB
Inventors: James Humble Richard; James Wiseman Garry; Charles Smith Andrew
Original assignee: Alcon Components Ltd
Current assignee: Alcon Components Ltd
Priority date: 2016-03-26
Filing date: 2016-03-26
Publication date: 2017-09-27
Anticipated expiration: 2036-03-26
Also published as: GB201605145D0; GB2548632B

Abstract

A disc brake caliper body 1 comprises a mounting side bracket 11 and a non-mounting side bracket 12 that extend along a circumferential direction of the body. Each bracket comprises at least one cylinder housing portion that receives corresponding brake cylinders. First and second bridging members 20, 30 interconnect the brackets at leading 2 and trailing 3 ends of the caliper body respectively. At least one of the bridging members comprises a cavity 21 that extends in the circumferential direction of the body. The cavity may be a blind hole or a through hole. At least one of the bridging members may further comprise a fluid channel that extends in a lateral and/or radial direction of the body. The caliper body may further comprise at least one cooling channel that extends along a bottom edge of one of the brackets and a third bridging member 40 that connects the brackets at a central portion along the circumferential direction of the body.

Description

Lightweight Disc Brake Caliper Body

The present invention relates to a lightweight disc brake caliper body, in particular a disc brake caliper body for brake systems of racing cars. The invention further relates to a caliper for a disc brake that comprises such a body and a braking system comprising the caliper body.

In a disc brake system, the brake caliper is arranged astride of the outer circumferential edge of the brake disc. The caliper body usually comprises two elongated brackets that are arranged on opposite sides of the brake disc, so as to face opposite braking surfaces of the disc. The brackets of the caliper body are interconnected by one or more bridging members that straddle the circumferential edge of the brake disc. At least one of the elongated brackets has a cylinder housing portion suitable for receiving brake cylinders with hydraulic pistons. The brake cylinders exert a thrust action on friction pads, which are arranged between the brackets and the braking surfaces of the brake disc. Upon activation of the hydraulic brake cylinders, the friction pads are pressed against the braking surfaces of the brake disc to exert a braking action on the vehicle.

Typically, brake caliper bodies are made from metals like aluminium, aluminium alloys or cast iron. The brake caliper bodies can be produced by machining of a metal block but also by casting, or a combination of the two. Known caliper bodies are either produced as a single piece (so called monoblock) or in two similarly sized pieces, which are typically interconnected by lateral mounting screws.

During a braking event, the forces exerted by the braking pads on the brake disc cause reaction forces, which are introduced into the brake caliper body. As such, the brake caliper body must exhibit high structural integrity, especially in racing environments, to withstand inadvertent deformation of the body. In view of this structural integrity requirement, prior art calipers exhibit extremely rigid and heavy body structures which are known to add weight and bulk to the known braking systems.

In racing vehicles, there is an ever increasing need to reduce the weight of every vehicle part. Accordingly, there is a need for brake caliper bodies that are capable of withstanding extreme braking forces and, at the same time, are extremely low in weight to increase the performance of the racing vehicles.

It is, therefore, an object of the present invention to provide a new brake caliper body that exhibits lower weight with substantially the same structural stability as commonly known caliper bodies. It is a further object of the invention to provide a lightweight caliper body with improved cooling properties.

According to a first embodiment of the invention, the invention relates to a disc brake caliper body comprising a mounting side bracket and non-mounting side bracket extending along a circumferential direetion of the body, each bracket comprising at least one cylinder housing portion for receiving corresponding brake cylinders. First and second bridging members are arranged for interconnecting the brackets at a leading and a trailing end of the caliper body, wherein at least one of the bridging members eomprises a cavity extending substantially in the circumferential direction of the body.

In prior art solutions, the bridging members of the disc brake caliper body are manufaetured as solid metal pieces that extend between the mounting and nonmounting side brackets. In order to reduce weight, some solutions propose to arrange openings (sometimes called windows) extending radially through the bridging members that can result in substantially reduced caliper body stability. In contrast to this, it was found that cavities extending into or through the bridging members in a circumferential direetion do not affect the stability of the caliper significantly.

As will be described in more detail below, the direetions of the caliper body mainly relate to its orientation with respect to the brake dise. As such, the circumferential direction of the brake caliper body refers to the circumferential edge of the corresponding brake disc and is in a plane with the longitudinal axis of the brake caliper body. The radial direction of the caliper body corresponds to the radial axis of the brake disc and hence extends from the bottom to the top surface of the ealiper body. Finally, a lateral direction of the caliper body is parallel to a rotational axis of the brake disc.

In another embodiment, the cavity in the at least one bridging member is a blind hole, which extends from a leading or trailing end towards the centre of a caliper body. In particular, if the cavity is arranged within the first bridging member at the leading end of the caliper body, the cavity preferably extends from the leading end towards the centre of the caliper body. Similarly, if the cavity is arranged within the second bridging member at the trailing end of the caliper body, the cavity preferably extends from the trailing end towards the centre of the caliper body. The particular arrangement of this embodiment is easy to manufacture, for example by machining material off from the trailing and/or leading end of the caliper body. In more detail, the cavities can be produced by drilling or milling the leading end of the first bridging member and/or the trailing end of the second bridging member. Of course, the blind hole of this embodiment could also extend from an inner side end of the first or second bridging member towards the leading or trailing end respectively. In one embodiment, both the first and second bridging members comprise a cavity extending in the circumferential direction of the caliper.

Constructing the cavity as a blind hole is particularly advantageous if the bridging members comprise fluid channels that must not connect with the cavity extending through the bridging member. In this case, the blind hole can assist in cooling fluids conducted through the bridging member via said fluid channels.

In another embodiment, the cavity is a through hole, which extends through at least one bridging member, between a leading or trailing end to the centre of a caliper body. In other words, the cavity of this embodiment extends circumferentially through the entire bridging member. As such, the cavity starts from the leading end in the case of the first bridging member and from the trailing end in the case of the second bridging member and continues to a second end of the respective bridging member, the second end being arranged facing the centre of the caliper body. The through hole may have a constant cross-section along the circumferential direction of the bridging member. Alternatively, the through hole may exhibit a varying cross-section, particularly if functioning members of the bridging member are to be avoided. The through hole may have a substantially funnel- or hourglass-like shape.

As mentioned previously, at least one of the bridging members may comprise a fluid channel, such as a brake fluid or coolant channel, extending in a substantially lateral and/or radial direction of the body. In this embodiment, the cavity will be constructed so as to avoid the fluid channel but can be used to cool the coolant or hydraulic brake fluid within the channel.

According to another embodiment, the caliper body further comprises at least one coolant channel extending along a bottom end of at least one of the brackets. The coolant channel is preferably arranged separate from the at least one bracket so as to be exposed to airflows surrounding the caliper body. The at least one cooling channel may be a fluid conduit, which is only attached to the bottom end of one of the brackets along its top edge. The cooling channel may be arranged radially below the at least one cylinder housing portion of the at least one bracket to achieve improved cooling of the brake cylinders.

In another embodiment, the at least one cooling channel has a substantially V-shaped profile, when viewed from the side. Accordingly, the at least one V-shaped cooling channel comprising a first and a second side channel portion wherein each side channel portion extends downwards from a common turning point. This arrangement is particularly advantageous if the at least one bracket comprises two or more cylinder housing portions that are circumferentially spaced from each other. In this case, the common turning point of the V-shaped cooling channel is preferably arranged between the two cylinder housing portions. Thus, the cooling channel is located in close proximity to the circumferential edge of the cylinder housing portions providing the best possible cooling effect.

According to another embodiment, the caliper body comprises a first cooling channel extending along the bottom end of the mounting side bracket and a second cooling channel extending along the bottom end of the non-mounting side bracket.

According to another aspect, the caliper body comprises a third bridging member for connecting the brackets at a central portion along the circumferential direction of the body. The third, central bridging member may be distanced from the first and second bridging members in the circumferential direction by a connecting portion. The connecting portion extends circumferentially between the third bridging member and the first and/or bridging member respectively.

In another embodiment, the connecting portion comprises a reduced radial thickness compared to the first and/or second and/or third bridging members. In other words, the connecting portion is a relatively thin layer of material spanning the distance between the first/second bridging member and the third bridging member. The connecting portion further improves stability of the caliper body without adding extensive amounts of weight.

In another embodiment, the connecting portion comprises at least one opening extending through the connecting portion in a radial direction of the caliper body. The at least one opening is preferably a slot substantially extending along the circumferential direction of the body. In order to achieve a further weight reduction, at least one opening of the connection portion may extend into a central side end portion of the first or second bridging member. If the bridging member comprises a cavity that is formed as a through hole, as described hereinbefore, the at least one opening may connect to the through hole of the respective bridging member.

The invention further relates to a brake caliper and a disc brake comprising the caliper body described hereinbefore.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying figures, in which:- FIG. 1 shows a perspective top view of a caliper body according to a first embodiment of the present invention; FIG.2 shows a perspective bottom view of the caliper body of FlG.l; FIG.3 shows a plan view of the caliper body shown in FIG.l; FIG.4 shows a cross-section along axis A-A shown in FIG 3; FIG.5 shows a perspective bottom view of the caliper body shown in FIG.l; FIG.6 shows a side view of the caliper body shown in FIG.l.

Figure 1 shows a perspective top view of a first embodiment of the disc brake caliper body. The disc brake caliper body 1 comprises a mounting side bracket 11 with mounting holes 111, 112 for mounting the caliper body 1 to a mounting structure of the vehicle frame. The body 1 further comprises a non-mounting side bracket 12, which is connected to the mounting side bracket 11, via first, second and third bridging members, 20, 30 and 40.

The mounting side bracket 11 and the non-mounting side bracket 12 of the body 1 extend in a circumferential direction 'x' which is aligned with a circumference of a corresponding brake disc (not shown). A radial direction 'z' of the brake caliper extends along a radial axis of a corresponding brake disc, that is, from the bottom to the top of the body 1. The lateral direction 'y' indicated in Figure 1 is a direction of the caliper body that is parallel to the rotational axis of the corresponding brake disc.

As can be derived from Figures 2 and 5, the mounting side bracket 11 and the nonmounting side bracket 12 each comprise two cylinder housing portions 14, 15, 18, 19 for receiving corresponding brake cylinders. The brackets 11, 12 may be profiled around the cylinder housing portions 14, 15, 18, 19 to further reduce the weight of the caliper body 1. A first bridging member 20 interconnects the brackets 11 and 12 at a leading end 2 of the caliper body 1. A second bridging member 30 interconnects the brackets 11 and 12 at a trailing end 3 of the caliper body 1. As mentioned hereinbefore, when the brake pads are pressed against the brake disc during use of the braking system. reacting forces will act on the brackets 11, 12, pushing the latter away from each other in the lateral direction 'y'. That is, during a braking event, the bridging members 20, 30 and 40 are subject to substantial tensioning stresses caused by the reaction forces. Traditionally, at least the first and second bridging member 20, 30 at the leading and trailing end 2, 3 of the body 1 were constructed as solid metal pieces to provide sufficient structural stability to absorb the lateral reaction forces.

In order to further reduce the weight of the caliper body 1, it was found that the first and second bridging member 20, 30 do not have to be formed of solid metal but can comprise circumferential cavities 21, 31, extending inside the respective bridging members 20, 30. Examples of circumferential cavities according to the first embodiment are shown in Figures 1, 2, 4 and 5. Accordingly, the caliper body 1 of the first embodiment comprises a first cavity 21 (Figure 1) extending circumferentially within the first bridging member 20 and a second cavity 31 (Figure 2), extending circumferentially within the second bridging member 30. Figures 2 and 4 further illustrate that the cavities 21, 31 essentially divide the first and second bridging members 20, 30 into a double I-beam structure comprising an upper I-beam 22, 32 separated from a lower I-beam 23, 33 by the respective cavity 21, 31.

The sectional view in Figure 4 shows that the cavities 21 and 31 are formed as blind holes, which extend from the leading end 2 or the trailing end 3 of their respective bridging member 20, 30 towards the centre of the caliper body 1. In this embodiment, the cavities 21, 31 do not extend through the entire length of the bridging members 20, 30 to prevent leakage of hydraulic fluid or coolant from the fluid channels 27, 37, which, in this embodiment extend through the bridging members 20, 30 in a lateral direction. Although the embodiments shown in Figures 1 to 6 comprises blind holes as cavities 21 and 31, the skilled person would understand that the cavities could in principle extend through the bridging members 20, 30 entirely, that is from a leading or trailing end of the respective bridging member towards their inner or central side end.

The cavities 21 and 31 not only reduce the weight of the caliper body 1, but provide for improved cooling properties, particularly inside the bridging members by increasing the cooling surface area of the first and second bridging members 20, 30. According to the embodiment shown in Figure 4, the cavity 21, 31 may assist in cooling fluid that is transported through the fluid channels 27 and 37 respectively.

Figure 1 further illustrates that the central bridge 40 is connected to the first bridging member 20 by means of a connecting portion 50. The connecting portion 50 has a reduced radial thickness compared to the bridging members 20, 40. The connecting portion 50 further comprises three openings 53, 54, 55, which are constructed as parallel, circumferential slots extending radially through the connecting portion 50. The slots 53, 54, 55 divide the connecting portion into two, laterally spaced bars 51, 52, connecting the third, central bridging member 40 to the first bridging member 20. At least one of the openings 53, 54, 55 extends into the bridging member 20 as is more readily derivable from Figures 2 and 4. In this embodiment, the central slot opening 53 extends into the second bridging member 20, that is, beyond first flange members 116, 126 of the mounting and non-mounting side brackets 11, 12. The first flange members 116, 126 define a border between the connecting portion 50 and the bridging member 20, in the circumferential direction 'x'. That is, when looking at the sectional view of Figure 4, anything outside of the flange members 116, 115 shall be considered as part of the first and second bridging members 20, 30, while material between the flange sections 115, 116 is either part of the connecting portions 50, 60 or the first bridging member 40.

In the embodiment shown in Figure 1, the third bridging member 40 is connected to the second bridging member 30 via a similar connecting portion 60. The connecting portion 60 comprises a reduced radial thickness compared to the second and third bridging members 30, 40. The connecting portion 60 also comprises slot openings 63, 64, 65 which divide the connecting portion 60 into two laterally distant connecting bars 61, 62. The central slot opening 63 extends past the second flange members 115, 125 of the mounting and non-mounting side brackets 11, 12, into the second bridging member 30.

The illustration of Figure 1 further includes a guide groove 25 that extends laterally around the leading end side of the second bridging member 20. The guide groove 25 further reduces the weight of the brake caliper 1 and can be used to guide an external fluid channel for connecting the fluid supply of the mounting and non-mounting side brackets 11, 12.

Figures 2, 4 and 5 show that the caliper 1 of the first embodiment further comprises two exposed coolant channels 70, 80, which are arranged along the bottom surface 117, 127 of the mounting and non-mounting side brackets 11, 12. A first exposed cooling channel 70 extends below the cylinder housing portions 14, 15 of the mounting side bracket 11, whereas a second exposed cooling channel 80 extends below the cylinder housing portions 18, 19 of the non-mounting side bracket 12. The exposed cooling channel 70, 80 exhibit a substantially V-shaped profile as can be derived from Figures 2 and 5. As such, the coolant channels 70, 80 comprise first and second side channel portions 71, 72, 81, 82, extending downwards, that is away from the bottom end 117, 127 of the brackets 11, 12, starting at a common turning point 73, 83. The common turning point 73, 83 is a maximum turning point, which is located centrally between the circumferentially spaced cylinder housing portions 14, 15 and 18, 19 respectively and marks the radially highest point of the V-shaped coolant channels 70, 80.

The caliper body 1 also comprises openings 16, 17 that extend through the brackets 11, 12 between the cylinder housing portions 14, 15 and 18, 19 respectively. The openings 16, 17 further improve the cooling characteristics and decrease weight of the caliper body 1.

The invention is not restricted to the particular embodiment described with reference to the attached illustrations. In particular, the cavities 21 and 31 could be formed as through holes that extend through the entire bridging member 20, 30. Furthermore, only one of the two end bridging members 20, 30 may include said cavity.

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 comprising at least one cylinder housing portion for receiving corresponding brake cylinders, • a first bridging member for interconnecting the brackets at a leading end of the caliper body; • a second bridging member for interconnecting the brackets at a trailing end of the caliper body, wherein at least one of the bridging members comprises a cavity extending substantially in the circumferential direction of the body.

2. The disc brake caliper body of claim 1, wherein the cavity is a blind hole, which extends from a leading or trailing end towards a centre of the caliper body.

3. The disc brake caliper body of claim 1, wherein the cavity is a through hole, which extends through the at least one bridging member, between a leading or trailing end towards a centre of the caliper body.

4. The disc brake caliper body of any of claims 1 to 3, wherein the first and second bridging members each comprise a cavity extending substantially in the circumferential direction of the body.

5. The disc brake caliper body of any of claims 1 to 4, wherein the at least one of the bridging members further comprises a fluid channel extending in a substantially lateral and/or radial direction of the body.

6. 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 comprising at least one cylinder housing portion for receiving corresponding brake cylinders. • a first bridging member for interconnecting the brackets at a leading end of the caliper body; • a second bridging member for interconnecting the brackets at a trailing end of the caliper body, wherein the caliper body further comprises at least one cooling channel extending along a bottom end of at least one of the brackets.

7. The disc brake caliper body of claim 6, wherein the at least one cooling channel is arranged radially below the at least one cylinder housing portion of the at least one bracket.

8. The disc brake caliper body of claim 6 or 7, wherein the at least one cooling channel has a substantially V-shaped profile, when viewed from the side.

9. The disc brake caliper body of claim 8, wherein the at least one V-shaped cooling channel comprises a first and a second side channel portion, wherein each side channel portion extends downwards from a common turning point.

10. The disc brake caliper body of claim 9, wherein the at least one bracket comprises at least two cylinder housing portions, said at least two cylinder housing potions being circumferentially spaced from each other, and wherein the common turning point of the V-shaped cooling channel is arranged between the two cylinder housing portions.

11. The disc brake caliper body of any of claims 6 to 10, wherein the body comprises a first cooling channel extending along the bottom end of the mounting side bracket and a second cooling channel extending along the bottom end of the non-mounting side bracket.

12. 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 comprising at least one cylinder housing portion for receiving corresponding brake cylinders. • a first bridging member for interconnecting the brackets at a leading end of the caliper body; • a second bridging member for interconnecting the brackets at a trailing end of the caliper body, wherein the caliper body further comprises a third bridging member for connecting the brackets at a central portion along the circumferential direction of the body.

13. The disc brake caliper body of claim 12, wherein at least one of the first and second bridging members is connected to the third bridging member by a connecting portion extending circumferentially between the first or second bridging member and the third bridging member.

14. The disc brake caliper body of claim 13, wherein the connecting portion comprises a reduced radial thickness compared to the first and/or second and/or third bridging members.

15. The disc brake caliper body of claim 13 or 14, wherein the connecting portion comprises at least one opening extending through the connecting portion in a radial direction of the caliper body.

16. The disc brake caliper body of claim 15, wherein the at least one opening is a slot substantially extending in the circumferential direction of the body, and wherein the at least one opening extends into a central side end portion of the first or second bridging member.

17. A brake caliper comprising the caliper body of any of claims 1 to 16 and a plurality of brake cylinder housings adapted to be received in the cylinder housing portions of the first and second brackets.

18. A disc brake comprising a braking disc and the brake caliper of claim 17.