GB1566002A

GB1566002A - Disc brakes

Info

Publication number: GB1566002A
Application number: GB566677A
Authority: GB
Original assignee: Tokico Ltd
Current assignee: Tokico Ltd
Priority date: 1976-02-12
Filing date: 1977-02-11
Publication date: 1980-04-30
Also published as: JPS5297079A; BR7700880A

Description

(54) IMPROVEMENTS IN DISC BRAKES (71) We, TOKICO LTD., a Japanese body corporate of 6-3, Fujimi 1-chome, Kawasaki-ku, Kawasaki-shi, Kanagawaken, Japan, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: - This invention relates to a disc brake and more particularly, to a floating caliper type disc brake of relatively large size, especially for use in a lorry.

There have been proposed and in practice employed a great variety of disc brakes. However, conventional disc brakes generally present a problem in respect to avoidance of vibration when the disc brake employs a relatively heavy floating member. And in the disc brake in which the floating caliper comprises a cylinder member and a bridge piece, in the mounting of the floating caliper, the cylinder member and the bridge piece cannot be tightened together as desired which makes it difficult to provide a sufficiently rigid floating caliper.

Therefore, an object of the present invention is to provide a disc brake which can effectively overcome the difficulty possessed by the conventional disc brakes referred to hereinabove.

According to the present invention, a disc brake comprises a torque member adapted to be fixedly secured to the body of a vehicle and having a pair of arms at its leading and trailing ends, respectively, with respect to the intended normal direction of disc rotation, said arms having through bores extending transversely thereof, a floating caliper slidably supported on said torque member by means of a pair of sleeves respectively received in said through bores in said arms for slidable movement therein and a pair of tie rods extending respectively through each of said sleeves, a first friction pad disposed on one side of a brake disc and supported by said torque member and a second friction pad disposed on the opposite side of said brake disc and supported by said floating caliper, the fitting relationship between the sleeve and the arm bore at the leading end of said torque member differing from the fitting relationship between the sleeve and arm bore at the trailing end of said torque member whereby in braking, the braking force provided by the friction pad supported by the floating caliper is transmitted to the torque member arm at the leading end of the torque member.

The weight of the torque member is thus reduced, the strength of the torque member is increased and the rigidity of the floating member is increased.

The invention is further described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a plan view of a first embodiment of disc brake constructed in accordance with the present invention showing a portion thereof in cross-section; Fig. 2 is a side elevational view of said disc brake as seen along substantially the line II-II of Fig. 1; Fig. 3 is similar to Fig. 2, but shows a second embodiment of disc brake constructed in accordance with the present invention; and Fig. 4 is a fragmentary cross-sectional view showing the interfitting relationship between one rod and the associated sleeve of a further embodiment.

The present invention will be now described referring to the accompanying drawings and more particularly, to Figs. 1 and 2 thereof wherein the first embodiment of disc brake of the invention is shown.

The disc brake generally comprises a torque member 1 adapted to be fixedly secured to the body of a vehicle (not shown), a pair of space tie rods 2, 3 which transversely extend through the torque member 1 at the opposite ends of the latter, a floating caliper 6 which includes a cylinder member 4 extending between and fixedly secured to one end of the rods 2, 3 disposed at the opposite ends of the torque member 1, respectively and a caliper reaction body 5 extending between and fixedly secured to the other end of the rods 2, 3, respectively, friction pads 7, 8 disposed on the opposite sides of a brake disc (not shown) between the rods 2, 3 and a pair of pistons 9, 9 disposed within separate chambers 4a defined in the cylinder member 4 for applying one of the friction pads 7 against the disc.

The torque member 1 has an arm la at the inlet or leading end of the torque member, an arm 1b at the outlet or trailing end of the torque member and an intermediary beam ic extending between and connecting the lower ends of the arms la, 1b together. The lower end of each of the arms la, lb is further provided with a transverse through bore through which a fastening means such as a set screw (not shown), for example, extends to secure the torque member 1 to the vehicular body. The upper ends of the arms la, ib are provided with cylinder portions le, if, respectively, which define through bores lg, 1h therein, respectively and which are positioned between the cylinder 4 and caliper reaction body 5.

Extending through the bores lg, 1h in the arms la, ib, respectively, are sleeves 10, 11 through which the above-mentioned rods 2, 3 extend, respectively to support the above-mentioned cylinder member 4 and caliper reaction body 5 at the ends of the rods. The sleeve 10 fits closely in the arm bore 1g whereas the sleeve 11 fits loosely in the arm bore 1h for the purpose to be described hereinafter, an annular space being provided between sleeve 11 and torque member arm bore lh. The cylinder member 4 and caliper reaction body 5 abut against the adjacent ends of the sleeves 10, 11 and are maintained in a predetermined spaced relationship under tension by means of the heads of the rods 2, 3 and nuts 12, 13 threaded at the ends of the rods opposite from the heads. In the arrangement as shown in Fig. 1, the rods 2, 3 are not designed to slidably move within the respectively associated bores ig, 1h in the cylinder portions le, if and thus, the surfaces of the rods 2, 3 need not be precisely finished and the cylinder member 4 and caliper reaction body 5 can be more firmly tightened together to increase the rigidity of the floating member 6. A precise finish has been necessary for the corresponding rods in the conventional disc brakes of this type. However, such arrangement of the rods 2, 3 is not absolutely necessary in the present invention. Instead, as is more clearly shown in Fig. 4, it is also within the scope of the present invention if the sleeve 10' is closely fitted on the rod 2' and the opposite ends of the sleeve are tapered to be received in the complementally shaped recesses in the bores of the cylinder member 4 and caliper reaction body 5. In this arrangement as shown in Fig. 4, the cylinder mernber 4 and caliper reaction body 5 can be more rigidly fastened together by the wedging action provided by the cooperating tapered ends of the sleeve and the complementally shaped recesses in the cylinder member and caliper reaction body.

Referring to Fig. 1 again, the center portion of the torque member 1 between the arms la, ib is formed with a recess 1d for receiving the friction pad 7 secured to the backing plate 7a which is secured to and adapted to be applied against the disc by the pistons 9, 9 in the cylinder member 4. The other friction pad 8 having the associated backing plate secured thereto is fixedly secured to the caliper reaction body S.

In braking, fluid under pressure is fed by a conventional suitable means (not shown) into the fluid chamber 4a, 4a defined between the outer ends of the pistons 9, 9 and the adjacent wall of the cylinder member 4 and acts on the pistons at the outer ends thereof. Upon receiving the fluid pressure thereon, the pistons 9, 9 extend to apply the friction pad 7 against one side of the brake disc whereupon a reaction force is produced. The thus produced reaction force acts to move the cylinder member 4 away from the brake disc. Such movement of the cylinder member 4 in turn moves the caliper reaction body 5 integral with the cylinder body 4 in the same direction as the cylinder member which in turn applies the friction pad 8 secured to the caliper reaction body 5 against the other side of the brake disc whereby braking force is applied to the brake disc on the opposite sides thereof.

In the braking operation described hereinabove, in order to prevent foreign matter from entering the annular spaces between the cylinder portions le, if and sleeves 10, 11 when the sleeves 10, 11 slidably move within the cylinder portions le, lf, respectively, conventional boots 14, 14 are disposed about the opposite ends of the sleeves 10, 11 between the cylinder member 4 and caliper reaction body 5, respectively.

Details of the braking action supplied by the first embodiment of the invention will be described referring to Figs. 1 and 2 hereinbelow.

In the first embodiment as shown in Figs. 1 and 2, although one of the sleeves 10 is closely fitted in the corresponding bore 1g of the torque member cylinder portion le, the other sleeve 11 is freely received in the corresponding bore lh of the torque member cylinder portion lf.

Thus, assuming that the brake disc is rotating in the arrow direction as shown by reference numeral 15 in Figs. 1 and 2, in the braking of the brake disc, the friction pad 7 biases the torque member 1 in the arrow direction as shown by reference numeral 16 in Fig. 1 and the braking force provided by the pad 7 is directly transmitted from the torque member 1 through the outlet end arm 1b to the vehicular body (not shown). On the other hand, the braking force provided by the other friction pad 8 biases the torque member 1 in the same direction as that in which the pad 7 biases the torque member, but since the friction pad 8 is fixedly secured to the caliper reaction body 5 for movement therewith, the braking force provided by the friction pad 8 in the arrow direction 16 moves the caliper reaction body 5 in the same direction. Since caliper reaction body 5 is supported at the opposite ends by the rods 2, 3, the biasing force acting on the caliper reaction body 5 is transformed into a force which biases the rods 3, 3 in the arrow direction 16. Since the rod 3 and more particularly, the sleeve 11 is freely received in the torque member cylinder portion lf, the biasing force provided by the friction pad 8 is transmitted through the rod 2, sleeve 10 and inlet end arm la to the torque member 1. Thus, it will be appreciated that in the disc brake as described the whole braking force by the brake is transmitted to the vehicular body in two halves through the two torque member arms la, lb, respectively.

The second embodiment as shown in Fig. 3 is substantially similar to the first embodiment except that the axes of the rods 2, 3 and more particularly, of the sleeves 10", 11' are inwardly offset with respect to the axes of the bores lug', lah', respectively. Although both axes are shown offset in this figure, it is to be understood that only one of the rods 2, 3 and of the respective sleeves 10,' 11' may be so arranged, in which case the other, if at the trailing end of the torque member would have the sleeve and torque arm bore interfitting loosely, or if at the leading end have them interfitting closely.

Although the second embodiment is identical to the first embodiment with respect to the fact that the braking force provided by the pad 8 secured to the caliper reaction body 5 is transmitted to the torque member 1 through the rod 2 and more particularly, the inner side of the sleeve associated with the rod 2 or the side of the sleeve facing the other rod 3, the second embodiment having the eccentric arrangement of rod and sleeve units is different from the first embodiment with respect to the fact that -even when the disc is rotating in the direction opposite from the arrow direction 15, the second embodiment of disc brake can effect braking operation in the same manner as that in which the brake effects the braking operation when the disc is rotating in the the arrow direction 15.

Furthermore, preloads can be applied to the sleeves and rods, that is, the sleeves can have a compressive preload applied thereto and the rods can have a tension preload applied thereto, respectively. With the application of preloads to the sleeves the rods, when the disc brake is applied, the rods resist deformation until the mag nitude of a load applied to the rods by fluid pressure reaches that of the tension force applied to the rods as the preload and thus, the axial deformation of the rods can be minimized and at the same time, the axial rigidity of the rods can be increased.

In the embodiment of Figs. 1 and 2, the opposite ends of the sleeves 10, 11 are partially and sealingly received in the cylinder member 4 and caliper reaction body 5, respectively and this arrangement of the sleeve is advantageous in that each of the sleeves can also arrest a force perpendicular to the axis thereof. However, it will be, of course, appreciated that such arrangement of the sleeves is not an essential feature of the present invention.

As mentioned hereinabove, each of the torque member arms receives one half of the whole braking force of the disc brake and transmits such partial braking force to the vehicular body and the rods 2, 3, exclusively act to abut against the cylinder member 4 and caliper reaction body 5.

Only the sleeves 10, 11 slidably move with respect to the torque member 1. Such arrangement of the torque member arms, rods and sleeves is different from that of any of the conventional corresponding devices in which the rods not only abut against the cylinder member and caliper reaction body, but also are slidably movable with respect to the torque member.

Thus, the present invention significantly contributes in increasing the rigidity of the device and especially, of the floating member, reducing the size and weight of the torque member and other aspects.

Still furthermore, since the rods ex clusively act to abut against the cylinder member and caliper reaction body, but do not slidably move with respect to the torque member, the rods are not required to be so precisely machined as is necessary for the corresponding parts of the conventional disc brakes. Thus, the present invention provides improvements over the conventional disc brakes with respect to production efficiency and cost.

While preferred embodiments of the invention have been shown and described in detail, it will be understood that they are for the illustration only and are not to be taken as a definition of the invention, reference being had for this purpose to the appended claims.

WHAT WE CLAIM IS: 1. A disc brake comprising a torque member adapted to be fixedly secured to the body of a vehicle and having a pair of arms at its leading and trailing ends, respectively, with respect to the intended normal direction of disc rotation, said arms having through bores extending transversely thereof, a floating caliper slidably supported on said torque member by means of a pair of sleeves respectively received in said through bores in said arms for slidable movement therein and a pair of tie rods extending respectively through each of said sleeves, a first friction pad disposed on one side of a brake disc and supported by said torque member and a second friction pad disposed on the opposite side of said brake disc and supported by said torque member and a second friction pad disposed on the opposite side of said brake disc and supported by said floating caliper, the fitting relationship between the sleeve and the arm bore at the leading end of said torque member differing from the fitting relationship between the sleeve and arm bore at the trailing end of said torque member whereby in braking, the braking force provided by the friction pad supported by the floating caliper is transmitted to the torque member arm at the leading end of the torque member.

2. A disc brake as claimed in claim 1, in which said sleeve and torque arm bore at the trailing end of said torque member interfit loosely and said sleeve and torque member arm bore at the leading end of said torque member interfit closely.

3. A disc brake as claimed in claim 1 or 2, in which the axis of at least one of said rods and of at least one of said sleeves in which the rod is received is offset with respect to the axis of the said torque arm bore in which the sleeve and rod are received, respectively.

4. A disc brake as claimed in claim 1, 2 or 3 in which an annular space is defined between said sleeve and said torque member arm bore at the trailing end of said torque member.

5. A disc brake as claimed in any preceding claim, in which said floating caliper includes a cylinder body and a reaction body tightened together by said tie rods.

6. A disc brake as claimed in claim 5, in which said sleeves abut at the opposite ends thereof against said cylinder body and reaction body respectively.

7. A disc brake as claimed in claim 5 in which the opposite ends of said sleeves are wedged in said cylinder member and said reaction body, respectively.

8. A disc brake as claimed in claim 5, 6 or 7, in which boots are disposed about the opposite ends of said sleeves between said cylinder body, said arms and said reaction body.

9. A disc brake constructed substantially as herein described with reference to and as illustrated in Figures 1 and 2, Figure 3 or Figure 4 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. not slidably move with respect to the torque member, the rods are not required to be so precisely machined as is necessary for the corresponding parts of the conventional disc brakes. Thus, the present invention provides improvements over the conventional disc brakes with respect to production efficiency and cost. While preferred embodiments of the invention have been shown and described in detail, it will be understood that they are for the illustration only and are not to be taken as a definition of the invention, reference being had for this purpose to the appended claims. WHAT WE CLAIM IS:

1. A disc brake comprising a torque member adapted to be fixedly secured to the body of a vehicle and having a pair of arms at its leading and trailing ends, respectively, with respect to the intended normal direction of disc rotation, said arms having through bores extending transversely thereof, a floating caliper slidably supported on said torque member by means of a pair of sleeves respectively received in said through bores in said arms for slidable movement therein and a pair of tie rods extending respectively through each of said sleeves, a first friction pad disposed on one side of a brake disc and supported by said torque member and a second friction pad disposed on the opposite side of said brake disc and supported by said torque member and a second friction pad disposed on the opposite side of said brake disc and supported by said floating caliper, the fitting relationship between the sleeve and the arm bore at the leading end of said torque member differing from the fitting relationship between the sleeve and arm bore at the trailing end of said torque member whereby in braking, the braking force provided by the friction pad supported by the floating caliper is transmitted to the torque member arm at the leading end of the torque member.