Brakes – Wheel – Axially movable brake element or housing therefor
Patent
1995-02-22
1998-05-12
Graham, Matthew C.
Brakes
Wheel
Axially movable brake element or housing therefor
158 7344, B16D 55224
Patent
active
057494452
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a disk brake for a motor vehicle, comprising: which is a caliper straddling a brake disk, and the other of which is a carrier fixed to the vehicle; facing the disk, an opening closed by a piston; when the clamping means are actuated, these guide means comprising at least one guide pin fixed to one of the brake elements, and a blind bore formed in the other brake element and in which the guide pin slides, this guide pin and this bore respectively constituting first and second guide members exhibiting respective front parts formed by a free end of the guide pin and by the opening of the bore, and respective rear parts formed by a connected end of the guide pin and by the bottom of the bore; an elastically deformable annular sleeve surrounding the opening of the bore and the guide pin; and between the piston and the caliper, and applied to the disk when the clamping means are actuated.
Such brakes are well known in the prior art, as shown, for example, by document FR-A-2,353,755, or the equivalent document GB-A-1,572,451.
BACKGROUND OF THE INVENTION
A very old problem which is posed in brakes of this type, termed "sliding caliper" brakes, is that of the return of the caliper to its position of rest after the actuation of the brake.
In effect, contrary to the piston, which is moved directly by the hydraulic brake fluid, the caliper is moved solely by mechanical reaction of the piston on one of the pads which bears on the disk and must, what is more, slide over the guide pin or guide pins in order to return to its initial position, this return therefore being quite tricky.
Under these conditions, it is often the case that the pad facing that face of the disk opposite the one toward which the piston points rubs on the disk even when the brake is not actuated, and wears prematurely while unduly slowing the vehicle.
The invention is located within this context, and its object is to propose a sliding caliper disk brake of simple structure, but one in which the caliper nevertheless returns regularly to its position of rest as soon as the brake is released.
SUMMARY OF THE INVENTION
To this end, the brake of the invention, conforming, moreover, to the abovementioned preamble, is essentially characterized in that the rear part of at least one of the guide members which the caliper carries is further from the bottom of the cylinder than the front part of this guide member, and in that the air capable of escaping from the bore is at least partially contained inside the said sleeve.
Under these conditions, the air trapped in the blind bore and/or in the sleeve and which is expanded by the rise in temperature, which the actuation of the brake produces owing to the friction of the pads on the disk, pushes the caliper back into its position of rest by exerting a force directed along the axis of the guide pin or guide pins.
According to a first possible embodiment of the invention, the guide pin is carried by the caliper and the opening of the bore pierced in the carrier points in the same direction as the opening in the cylinder.
According to a second possible embodiment of the invention, the guide pin is carried by the carrier and the opening of the bore pierced in the caliper points in the opposite direction from that in which the opening in the cylinder points.
Other characteristics and advantages of the invention will emerge clearly from the description thereof which is given hereafter, by way of non-limiting indication, with reference to the appended drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan and partial section view of a brake, not in accordance with the invention;
FIG. 2 is a diagrammatic and partial section view of a brake in accordance with a first embodiment of the invention;
FIG. 3 is a diagrammatic and partial section view of a brake in accordance with a second embodiment of the invention;
FIG. 4 is a view in diagrammatic section of a brake in accordance with a variant of the first embodiment; and
FIG. 5 is a view in section along the line V--V of FIG. 4
REFERENCES:
patent: 4305483 (1981-12-01), Iveda
patent: 4427096 (1984-01-01), Stoka et al.
patent: 4446948 (1984-05-01), Meliuat
AlliedSignal Europe Services Techniques
Graham Matthew C.
McCormick Jr. Leo H.
Schwartz Chris
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