GB2473001A

GB2473001A - Disc Brake Caliper Body having a cooling aperture

Info

Publication number: GB2473001A
Application number: GB0914846A
Authority: GB
Inventors: Stephen James Hodgkins
Original assignee: Alcon Components Ltd
Current assignee: Alcon Components Ltd
Priority date: 2009-08-25
Filing date: 2009-08-25
Publication date: 2011-03-02
Anticipated expiration: 2029-08-25
Also published as: GB0914846D0; GB2473001B

Abstract

A disc brake caliper body 10 has a mounting limb 12 and a non mounting limb 14 each having at least one hydraulic cylinder therein, bridging and strap portions 16,18 extending between respective first and second ends of the limbs 12,14. The strap portion 18 is narrower than the bridging portion 16. The caliper body 10 further has a strengthening member 66 extending between the limbs 12,14, a first strengthening leg 86 extending from the strengthening member 66 to the bridging portion 16 and two further strengthening legs 88a,88b extending from the strengthening member 66 in a direction away from the bridging portion to the mounting and non-mounting limbs 12,14 respectively, wherein a disc cooling aperture 106 in the caliper body 10 is defined between the strap portion 18, strengthening member 66, limbs 12,14 and the two further strengthening legs 88a,88b. The cooling aperture 106 is preferably on the trailing side of the caliper and the caliper is preferably used with a ventilated disc brake (fig 10).

Description

Disc Brake Caliper Body The present invention relates to a disc brake caliper body and a disc brake caliper assembly including such a body.

A typical disc brake caliper body includes a pair of limbs which, in use, are positioned on opposing sides of a brake disc. The caliper body may be of the fixed caliper type or the floating or sliding caliper type. A fixed caliper is, as its name suggests, fixed relative to the brake disc. Each limb is provided with at least one hydraulically operated piston which can move a brake pad associated with the limb into contact with the brake disc. The limbs are joined at their respective ends with bridges which are typically of equal dimensions to one another. A floating caliper, on the other hand, is able to move along an axis parallel to the rotational axis of the disc. For high performance applications such as, for example, racing and high performance road and track vehicles, fixed calipers are preferred as they are less prone to sticking than floating calipers.

For optimum braking performance a stiff caliper which is resistant to deflection under extreme braking loads is needed. This has lead to the development of caliper bodies which are provided with strengthening formations which extend between the limbs of the caliper body and around the periphery of the caliper body. With the addition of such formations the degree by which the caliper body shrouds the brake disc has increased which in turn has lead to heat retention issues.

It is an object of the present invention to provide a disc brake caliper body which seeks to at least mitigate this problem.

According to a first aspect of the present invention there is provided a disc brake caliper body having a mounting limb and a non mounting limb each having at least one hydraulic cylinder therein, a bridging portion extending between respective first ends of the limbs and a strap portion extending between respective second ends of the limbs, the strap portion being narrower than the bridging portion, the caliper body further having a strengthening member extending between the limbs at a position intermediate the bridging and strap portions, a first strengthening leg extending from the strengthening member to the bridging portion and two further strengthening legs extending from the strengthening member in a direction away from the bridging portion, said further strengthening legs extending to the mounting and non-mounting limbs respectively, wherein a disc cooling aperture in the caliper body is defined between the strap portion, strengthening member, limbs and further strengthening legs.

The disc cooling aperture permits heat to dissipate from the brake disc to the air surrounding the caliper body and hence limits the heat energy transmitted to the caliper body. In high performance braking systems ventilated brake discs are typically used. In a ventilated disc the opposing sides of the disc are separated by a plurality of fins or vanes. Rotation of the disc causes cooling air to be drawn through the disc by the vanes and expelled radially from the circumference of the disc. The provision of the cooling aperture reduces the amount by which heated air expelled from the brake disc in this manner impinges upon, and thus heats, the caliper body.

The disc cooling aperture is provided on the trailing side of the caliper body, with the term trailing being construed with reference to the normal, forward direction of rotation of the brake disc. It will be understood that during a braking event the brake disc is at it hottest at a rotational position that is on the immediate trailing side of the brake pads. By providing the cooling aperture at this location, more effective cooling of the brake disc can occur.

Each further strengthening leg preferably extends from the strengthening member to a brake pad abutment projection of a limb. Each further strengthening leg may include a through aperture which, in use, receives a fastener therethrough to permit attachment of a duct to the strengthening member. The through aperture is preferably provided at the junction of the further strengthening leg and the strengthening member. Each further strengthening leg is preferably of substantially uniform width along it's length between the through aperture and the limb. Each further strengthening leg is preferably of substantially uniform cross-section along it's length between the through aperture and the limb.

A further aperture is provided in the caliper body between the mounting limb, the strengthening member and the further strengthening leg closest the mounting limb. A corresponding further aperture is provided in the caliper body between the non-mounting limb, the strengthening member and the further strengthening leg closest the non-mounting limb.

The portion of the mounting limb which is between the mounting limb side strengthening leg and the strap portion has a greater cross-sectional area than the corresponding portion of the non-mounting limb which is between the non-mounting limb side strengthening leg and the strap portion, the cross-section being taken on a line which is transverse to the limbs. The cross-sectional area of the strap portion reduces in the direction from the mounting limb to the non-mounting limb. By minimising the dimensions of the portion of the caliper that extends between the limbs on the trailing side, the amount of heat energy that can be retained by the trailing side of the caliper is reduced.

The first strengthening leg which extends from the strengthening member to the bridging portion may merge into a rib of the bridging portion. The first strengthening leg may include a through aperture which, in use, receives a fastener therethrough to permit attachment of a duct to the strengthening member. The through aperture is preferably provided at the junction of the first strengthening leg and the strengthening member. The first strengthening leg is preferably of substantially uniform width along it's length between the through aperture and the bridging portion. The first strengthening leg is preferably of substantially uniform cross-section along it's length between the through aperture and the bridging portion.

According to a further aspect of the present invention there is provided a disc brake caliper body having a mounting limb and a non mounting limb each having at least one hydraulic cylinder therein, a bridging portion extending between respective first ends of the limbs arid a strap portion extending between respective second ends of the limbs, the strap portion having a cross-sectional area taken on a line parallel with one of the limbs which is less than a corresponding cross-sectional area of the bridging portion, the caliper body further having a strengthening member extending between the limbs at a position intermediate the bridging and strap portions, a first strengthening leg extending from the strengthening member to the bridging portion and at least one further strengthening leg extending from the strengthening member in a direction away from the bridging portion and joining one of the mounting and non-mounting limbs.

According to a further aspect of the present invention there is provided a disc brake caliper including the caliper body of the preceding aspects.

An embodiment of the present invention will now be described with reference to the accompanying figures in which: Figure 1 shows an isometric view of the radially outer side of a caliper body according to the present invention; Figure 2 shows a top plan view of the caliper body; Figure 3 shows a side view of the caliper body indicated by arrow A of figure 2; Figure 4 shows an end view of the caliper body indicated by arrow B of figure 2; Figure 5 shows an opposite side view of the caliper body indicated by arrow C of figure 2; Figure 6 shows an opposite end view of the caliper body indicated by arrow D of figure 2; Figure 7 shows a bottom plan view of the caliper body; Figure 8 shows another isometric view of the radially outer side of the caliper body; Figure 9 shoes an isometric view of the radially inner side of the caliper body; and Figure 10 shows an isometric view of a caliper including the caliper body of the present invention and a brake disc.

Referring to the figures there is shown a disc brake caliper body generally designated 10. The caliper body 10 is of the fixed type which is to say that, in use, the body 10 does not move relative to the brake disc to which it is associated. The caliper body 10 is of a monolithic construction and is formed from a billet of material such as, for example, aluminium or aluminium alloy. The caliper body 10 includes first and second limbs 12,14 which are connected to one another at respective opposing ends by a bridging portion 16 and a strap portion 18. The caliper body 10 is provided with a pair of spaced mounting apertures 20,22 which enable the caliper body 10 to be securely mounted to a vehicle structure such as, for example, a suspension or axle assembly. The mounting apertures 20,22 extend through one of the limbs 12 which is hereinafter referred to as the mounting limb 12. The other of the limbs 14 is hereinafter referred to as the non-mounting limb 14.

As can be seen from figure 10, the caliper body 10 is, in use, mounted relative to a brake disc 24. With reference to the rotational axis of the disc 24 the caliper body 10 has a radially inner side 26 and a radially outer side 28. The rotational direction of the disc 24 is indicated by arrow 30. With reference to the rotational direction 30 of the disc 24, the caliper body 10 has a leading side 32 and a trailing side 34. The bridging portion 16 is provided on the leading side of the caliper body 10 and the strap portion 18 is provided on the trailing side of the caliper body 10.

Each limb 12,14 is provided with a pair of cylindrical wells 36,38 within each of which, in use, there is provided a cylindrical piston. Each limb 12,14 is provided with a respective leading side well 36 and a trailing side well 38 The pistons and wells 36,38 oppose one another across a space 50 surrounded by the limbs 12,14, bridging and strap portions 16,18 within which a portion of a brake disc 24 is receivable. The wells 36,38 are connected by fluid passages (not shown) which extend through the caliper body 10 and which permit, in use, brake fluid to be supplied to the wells 36,3 8 to actuate the pistons. The mounting limb 12 is provided with a recessed aperture 40 to which a fluid supply connection can be connected. Recessed aperture 42 is a blanked fluid transfer port.

The portions 44,46 of the limbs 12,14 within which the wells 36,38 are located are shaped externally so as to partially follow the cylindrical interior shape of the wells 36,38. A through aperture 48 is provided between the wells 36,38 of each limb 12,14, which through aperture extends between the radially inner and outer sides 26,28 of the caliper body 10. The through apertures 48 permit cooling air pass between the limb portions 44,46 as will be described in greater detail below. The mouth 56,58 of each well 36,3 8 is at least partially surrounded by a flange 60. The trailing side of the non mounting limb 14 between the trailing side well 38 and strap portion 18 is provided with a further through aperture 52 which is provided for the purpose of overall weight reduction of the caliper body 10.

The caliper body 10 is further provided with peripheral strengthening ribs 62,64 in the region of the limb portions 44,46 within which the wells 36,38 are located. On the mounting limb 12, the strengthening rib 62 is provided across the limb portions 44,46 within which the wells 36,38 are located. On the non mounting limb 14, the strengthening rib 64 is again provided across the limb portions 44,46 within which the wells 36,38 are located and further extends around the edge of the trailing side of the non mounting limb 14 and the edge of the strap portion 18.

The caliper body 10 is further provided with a strengthening member or bridge 66 which extends between the limbs 12,14 and across the space 50 surrounded by the limbs 12,14, bridging and strap portions 16,18. The strengthening bridge 66 is connected to the flange 60 of each limb 12,14 which at least partially surrounds the mouths 56,5 8 of each well 36,38. The strengthening bridge 66 is connected to each respective limb flange 60 by respective leading and trailing side feet 68,70. The strengthening bridge 66 is thus connected to each limb 12,14 at two locations with the result that an aperture 72 is defined on each side of the caliper body 10 between the bridge 66, flange 60 and feet 68,70.

The radially outer side 74 of the strengthening bridge 66 is provided with leading and trailing side flanges 76,78 which extend across the caliper body between the limbs 12,14. The flanges 76,78 are separated by a central planar portion 80. The flanges 76,78 and planar portion 80 form part of a duct which, in use, channels a supply of cooling air to the limb through apertures 48. The duct is defined between the strengthening bridge 66 and a shroud (not shown) which is fitted thereto. The radially inner side 82 of the strengthening bridge 66 provides a planar guide surface 84 for the radially outer edge of brake pads fitted to the caliper body 10. In an alternative embodiment the strengthening bridge 66 may function solely to strengthen the caliper body 10 and hence not form part of a duct.

The caliper body 10 is further provided with additional strengthening legs 86,88 which extend from the strengthening bridge 66. The caliper body 10 is provided with a leading side strengthening leg 86 which extends from the leading side of the strengthening member 66 to the bridging portion 16. The strengthening leg 86 extends from a position of the strengthening member 66 which is substantially midway between the limbs 12,14. The strengthening leg 86 thus, in use, is aligned with and overlies the radially outer edge of the brake disc with which the caliper body 10 is associated, in use. The strengthening leg 86 is aligned with and extends parallel to the longitudinal centreline axis 108 of the caliper body 10. The strengthening leg 86 is aligned to and merged with a strengthening rib 90 of the bridging portion 16. At the juncture of the strengthening leg 86 with the strengthening bridge 66 there is provided an aperture 92 for a threaded fastener which, in use, is utilised to secure the aforementioned shroud to the caliper body 10.

The caliper body 10 is provided with a pair of trailing side strengthening legs 88a,88b which are hereinafter referred to as the mounting limb trailing side strengthening leg 88a and the non-mounting limb trailing side strengthening leg 88b so as to identify the limb 12,14 to which it is closest. Each strengthening leg 88a,88b extends from the trailing side of the strengthening member 66 and connects to a trailing side pad abutment projection 94 of each respective limb 12,14. The strengthening legs 88a,88b are parallel to one another and each leg 88a,88b is in turn parallel to the longitudinal centreline axis 108 of the caliper body 10. Each pad abutment projection 94 is provided with a pad abutment face 96 which, in use, abuts the trailing side edge of a brake pad. The caliper body 10 is provided with corresponding pad abutment projections 98 on the leading side of the body 10. Each leading side pad abutment projection 98 is provided with a pad abutment face 100 which, in use, abuts the leading side edge of a brake pad fitted to the caliper body 10.

Each strengthening leg 88a,88b extends from the strengthening member 66 at a lateral position that is between the leading side strengthening leg 86 and the limb 12,14 to which it is closest. At the juncture of each strengthening leg 88a,88b with the strengthening member 66 there is provided an aperture 102 for a threaded fastener which, in use, is utilised to secure the aforementioned shroud to the caliper body 10.

On respective sides of the caliper body 10 an aperture 104 is defined between the strengthening leg, 88a,88b, pad abutment projection 94, flange 60 and strengthening member 66. Each strengthening leg 88a,88b is of substantially uniform width and cross-section between the aperture 102 and the pad abutment projection 94.

A further aperture 106 is defined between the strengthening member 66, the strap portion 18, strengthening legs 88a,88b and trailing side pad abutment projections 94.

The position of the aperture 106 in the caliper body 10 is such that, in use, the brake disc 24 is at least partially received therein. This can be seen in figure 10. The provision of the aperture 106 enables more efficient cooling of the brake disc 24 by reducing the degree by which the brake disc 24 is shrouded by the caliper body 10 on the trailing side thereof. The spacing of the strengthening legs 88a,88b ensures that neither overlie the disc 24 in the same manner as the leading side strengthening leg 86.

This reduces the degree by which heated air expelled from the interior of the brake disc 24 impinges upon, and thus heats, the caliper body 10. It will be noted that, when viewed in plan, the strap portion 18 is significantly narrower than the bridge portion 16. This reduction in the size of the strap portion 18 in comparison to the bridge portion 16 is possible due to the provision of the strengthening member 66.

It will further be noted that the radially upper outer surface 110 of the strap portion 18 is inclined in the direction of the non-mounting leg 14 with the result that the cross-sectional area of the strap portion 18 reduces in the direction from the mounting leg 12 to the non-mounting leg 14. The provision of a strap portion 18 which is reduced in size compared to the bridge portion 16 produces a caliper body 10 which is lighter than a conventional caliper body where the limbs are connected by bridge portions of substantially equal size.

Claims

C'aims 1. A disc brake caliper body having a mounting limb and a non mounting limb each having at least one hydraulic cylinder therein, a bridging portion extending between respective first ends of the limbs and a strap portion extending between respective second ends of the limbs, the strap portion being narrower than the bridging portion, the caliper body further having a strengthening member extending between the limbs at a position intermediate the bridging and strap portions, a first strengthening leg extending from the strengthening member to the bridging portion and two further strengthening legs extending from the strengthening member in a direction away from the bridging portion, said further strengthening legs extending to the mounting and non-mounting limbs respectively, wherein a disc cooling aperture in the caliper body is defined between the strap portion, strengthening member, limbs and further strengthening legs.
2. A caliper body as claimed in claim I wherein each further strengthening leg preferably extends from the strengthening member to a brake pad abutment projection of a limb.
3. A caliper body as claimed in claim I or claim 2 wherein each further strengthening leg includes a through aperture which, in use, receives a fastener therethrough to permit attachment of a shroud to the strengthening member.
4. A caliper body as claimed in claim 3 wherein the through aperture is provided at the junction of the further strengthening leg and the strengthening member.
5. A caliper body as claimed in claim 4 wherein each further strengthening leg is of substantially uniform width along it's length between the through aperture and the limb.
6. A caliper body as claimed in claim 6 wherein each further strengthening leg is of substantially uniform cross-section along its length between the through aperture and the limb.
7. A caliper body as claimed in any preceding claim wherein a further aperture is provided in the caliper body between the mounting limb, the strengthening member and the further strengthening leg closest the mounting limb.
8. A caliper body as claimed in any preceding claim wherein a further aperture is provided in the caliper body between the non-mounting limb, the strengthening member and the further strengthening leg closest the non-mounting limb.
9. A caliper body as claimed in any preceding claim wherein the portion of the mounting limb which is between the mounting limb side strengthening leg and the strap portion has a greater cross-sectional area than the corresponding portion of the non-mounting limb which is between the non-mounting limb side strengthening leg and the strap portion, the cross-section being taken on a line which is transverse to the limbs.
10. A caliper body as claimed in claim 9 wherein the cross-sectional area of the strap portion reduces in the direction from the mounting limb to the non-mounting limb.
11. A caliper body as claimed in any preceding claim wherein the first strengthening leg extending from the strengthening member to the bridging portion merges into a rib of the bridging portion.
12. A caliper body as claimed in any preceding claim wherein the first strengthening leg includes a through aperture which, in use, receives a fastener therethrough to permit attachment of a shroud to the strengthening member.
13. A caliper body as claimed in claim 12 wherein the through aperture is provided at the junction of the first strengthening leg and the strengthening member.
14. A caliper body as claimed in claim 13 wherein the first strengthening leg is of substantially uniform width along its length between the through aperture and the bridging portion.
15. A caliper body as claimed in claim 14 wherein the first strengthening leg is of substantially uniform cross-section along its length between the through aperture and the bridging portion.
16. A disc brake caliper including a disc brake caliper body according to any preceding claim.