DISK BRAKE ROTOR

Abstract: A ventilated type disc brake rotor includes a spindle, a wheel hub rotatably supported by the spindle, a fitting portion fixed to the wheel hub, a brake pad engaging portion, a step portion for connecting the fitting portion with the brake pad engaging portion, and a plurality of reinforcing and cooling fins fixed on the outer periphery of the step portion which are separate, and radially project from the outer periphery of the step portion. The fins are also fixed at one end thereof to the brake pad engaging portion so that the fins are placed over the brake pad engaging portion.

Description: DISC BRAKE ROTOR BACKGROUND OF TEE INVENTION This invention relates to a disc brake rotor. Fig. 1 shows a conventional disc brake rotor 1. The disc brake rotor 1 is of a ventilated type and includes a spindle 2, a wheel hub 3 supported through bearings 4, 4' by the spindle 2. A fitting portion 5 of the disc brake rotor 1 is fixed to the wheel hub 3 by means of bolts 6 so that the disc brake rotor 1 can rotate together with a wheel (not shown). A circular brake pad engaging portion 7 is placed in an offset position in the rotation axis direction by way of a step portion 8 extending perpendicular to the fixing portion 5 of the disc brake rotor 1. A pair of brake pads 9 are placed -at both sides of the brake pad engaging portion 7. When the brake pads 9 are pressed against opposite brake pad engaging surfaces 10, 11 of the brake pad engaging portion 7, the brake rotor 1 is braked. Many cooling fins 12 are fixed between the brake pad engaging surfaces 10, 11 of the brake pad engaging portion 7 in radial directions. Friction heat produced during braking is transmitted by way of the step portion 8 and the fitting portion 5 to the wheel hub 3 so as to cool the brake rotor 1. In addition, the friction heat is radiated by means of the cooling fins 12 into the atomosphere. In such a conventional structure, the rigidity of the disc brake rotor is low because the fitting portion 5 and the brake pad engaging portion 7 are joined by the step portion 8 extending perpendicular thereto. Also, because an area in section of the step portion 8 is small, the cooling efficiency is poor. SUMMARY OF TBE INVENTION According to this invention, the configuration of a step portion which connects a fitting portion of a disc brake rotor with a brake pad engaging portion thereof is improved in such a way that the step portion can be reinforced. A plurality of cooling fins are separately provided at the outer periphery of the step portion. An area in section of the step portion can be increased so that the heat transmission efficiency and air blowing characteristics can be improved. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic sectional view showing a prior art disc brake rotor; Fig. 2 is a schematic vertical sectional view a disc brake rotor according to this invention; and Fig. 3 is a front view showing the disc brake rotor shwon in Fig. 2. DETAILED DESCRIPTION OF A PREFERRED EMBODINENT Referring now to Figs. 2 and 3, the same references designate the same or corresponding members or parts as in the prior art disc brake rotor shown in Fig. 1. A disc brake rotor 1 is of a ventilated type and includes a spindle 2, a wheel hub 3 supported through bearings 4, 4' by the spindle 2. A fitting portion 5 of the disc brake rotor 1 is fixed to the wheel hub 3 by means of bolts 6 so that the disc brake rotor 1 can rotate together with a wheel (not shown). A circular brake pad engaging portion 7 is placed in an offset position in the rotation axis direction by means of a step portion 8 extending perpendicular to the fixing portion 5 of the disc brake rotor 1. A pair of brake pads 9 are placed at both sides of the brake pad engaging portion 7 and face opposite brake pad engaging surfaces 10, 11 of the brake pad engaging portion 7. When the brake pads 9 are pressed against the brake pad engaging surfaces 10, 11 of the brake pad engaging portion 7, the brake rotor 1 is braked. The fitting portion 5 of the disc brake rotor 1 is joined to the brake pad engaging portion 7 by means of the step portion 8 which extends perpendicular thereto in the rotation axis direction. Many cooling fins 12 are fixed between the brake pad engaging surfaces 10, 11 of the brake pad engaging portion 7 in radial directions. Friction heat produced during braking is transmitted by way of the step portion 8 and the fitting portion 5 to the wheel hub 3 so as to cool the brake rotor 1. The friction heat is radiated by means of the cooling fins 12 into the atmosphere. A plurality of reinforcing and cooling fins 15 are placed on the outer periphery of the step portion 8. Those fins 15 are positioned separately at regular intervals as best shown in Fig. 3. The fins 15 are fixed at the left end thereof to the brake pad engaging portion 7 as shown in Fig. 2. The fins 15 extend radially in such a manner that the fins 15 are placed partly over the brake pad engaging portion 7 and the fins 12. Therefore, the rigidity and strength of the disc brake rotor 1 can be increased. It should be noted that other arrangements of the fins 15 can be employed. Through-holes 16 for the air flowing purpose are formed in the step portion 8 between the fins 15 in the radius directions. Grooves 17 are formed in the fitting portion 5 so as to be continuously connected with the through-holes 16 whereby air can flow through the throughholes 16 and grooves 17. In operation, the step portion 5, the fins 15 and brake pad engaging portion 7 are integrally rotated. When the disc brake rotor 1 rotates, air is forcibly produced near the brake pad engaging surface 10 so that the radiation efficiency can be increased. The area in section of the disc brake rotor 1 for the purpose of the heat transmission from the brake pad engaging portion to a support portion can be increased. Thus, the disc brake rotor 1 can be sufficiently cooled. Fade phenomena due to rotor superheatings can be prevented from occurring.

Claims: WEAT IS CLAIMED IS: 1. A ventilated type disc brake rotor attached to a wheel hub including: a fitting portion fixed to the wheel hub; a brake pad engaging portion; and a step portion for connecting the fitting portion with the brake pad engaging portion; the improvement comprising: a plurality of reinforcing and cooling fins fixed on the outer periphery of the step portion; the fins being separate; the fins radially projecting from the outer periphery of the step portion; and the fins being fixed at one end thereof to the brake pad engaging portion so that the fins are placed over the brake pad engaging portion. 2. A disc brake rotor as defined in claim 1, wherein the fins are positioned at regular intervals. 3. A disc brake rotor as defined in claim 1, wherein through-holes for the air flowing purpose are formed in the step portion in an intermediate position between the adjacent fins in radius directions. 4. A disc brake rotor as defined in claim 3, wherein grooves are formed in the fitting portion so as to be continuously joined to the through-holes

Inventors: TOKUNAGA, MASAYUKI
Applicants: NISSAN MOTOR CO., LTD.
Application year: 1983
Main classification: F16D65
IPC codes: F16D65