Fail-safe hydrualic brake apparatus

Claim 2

Hydraulic brake apparatus comprising: a housing; a first recess defined in said housing having an end wall and an endless outer peripheral wall; a second recess defined in said housing having an end wall and an endless outer peripheral wall surrounding and spaced outwardly from the outer peripheral wall of said first recess; a first flexible resilient actuator mounted in said housing and forming a first closed chamber with the end wall of said first recess, said first actuator being movable to expand and contract said first chamber in response to pressure changes in said first chamber to respectively apply and release a braking pressure; and a second flexible resilient actuator mounted in said housing and forming a second closed chamber with the end wall of said second recess, said second actuator being movable to expand and contract said second chamber in response to pressure changes in said second chamber to respectively apply and release a braking pressure.

Claim 3

Apparatus as claimed in claim 1 wherein the end wall of said second recess is annular and the end wall of said first recess is spaced axially from the end wall of said second recess with the outer peripheral wall of said first recess terminating at the inner periphery of the end wall of said second recess.

Claim 4

Apparatus as claimed in claim 2 wherein said first actuator includes a fixed end portion secured to said housing; a movable end portion; and an endless side wall extending therebetween having at least one corrugation formed therein, said side wall being operable to change its length and hence the distance between said end portioNs in response to pressure changes in said first chamber.

Claim 5

Apparatus as claimed in claim 3 wherein said second actuator includes inner and outer fixed end portions secured to said housing; a movable end portion; an inner side wall extending between said inner fixed end portion and said movable end portion, and an outer side wall extending between said outer fixed end portion and said movable end portion; and at least one corrugation formed in each of said inner and outer side walls, said inner and outer side walls being operable to change their lengths and hence the distance between the fixed and movable end portions of said second actuator in response to pressure changes in said second chamber.

Claim 6

Apparatus as claimed in claim 4 including an extension formed on the inner side wall of said second actuator and extending along the outer peripheral wall of said first recess, said inner fixed end portion being formed on said extension at the end thereof remote from said movable end portion.

Claim 7

Apparatus as claimed in claim 5 wherein said housing includes a main body portion having an opening therein defining the outer peripheral wall of said second recess, a cap portion mounted on said main body portion having an opening therein smaller than the opening in said main body and defining the outer peripheral wall of said first recess, and a cover member mounted in said cap portion and defining the end wall of said first recess.

Claim 8

Apparatus as claimed in claim 6 wherein the outer fixed end portion of said second actuator is clamped between said cap portion and said main body portion, and the inner fixed end portion of said second actuator and the fixed end portion of said first actuator are clamped between said cap portion and said cover member.

Claim 9

Apparatus as claimed in claim 7 including a piston member received in the openings in said main body and cap portions, said piston projecting into engagement with the movable end portion of said first actuator and having a peripheral side surface engaged with the inner side wall of said second actuator, and said piston having an enlarged outer portion overlying the movable end portion of said second actuator.

Claim 10

Apparatus as claimed in claim 8 including a port in said cover member communicating with said first chamber and a port in said cap portion communicating with said second chamber.

Claim 11

Apparatus as claimed in claim 8 wherein the side walls of said first and second actuators each comprises metal with an outer layer of elastomeric material.

Claim 12

Hydraulic brake apparatus comprising: a housing including a main body portion having an opening therein; a cap member mounted on said main body portion and having an opening therein coaxial with and smaller than the opening in said main body portion such that a shoulder is defined by said cap member at the juncture of said openings; a cover member mounted on the outer end of said cap member; a first flexible actuator received in the opening in said cap member and having a peripheral mounting flange clamped between said cap and cover members; said first actuator defining a first closed chamber with said cover member and having a movable end portion and an endless outer side wall extending between said movable end portion and said mounting flange, said side wall having at least one corrugation formed therein and being operable to change its length and hence the distance between said movable end portion and said cover member in response to pressure changes in said first chamber; a second flexible actuator received in the opening in said main body portion and having an outer peripheral mounting flange clamped between said cap member and said main body portion; said second actuator defining a second closed chamber with said shoulder and having a movable end portion, an outer side wall extending between said movable end portion and said outer mounting flange, an inner side wall extending between said movable end portion and said shoulder, an extension projecting into the opeNing of said cap member from said inner side wall, and an inner mounting flange on the end of said extension opposite said inner side wall; said inner mounting flange being clamped between said cap and cover members, and said inner and outer side walls of said second actuator each having at least one corrugation formed therein and being operable to change its length and hence the distance between the movable end portion and said shoulder in response to pressure changes in said second chamber.

Claim 13

Hydraulic brake apparatus comprising: a housing including a main body portion having an opening therein; a cap member mounted on said main body portion and having an opening therein coaxial with and smaller than the opening in said main body portion such that a shoulder is defined by said cap member at the juncture of said openings; a cover member mounted on the outer end of said cap member; a first flexible actuator received in the opening in said cap member and having a peripheral mounting flange clamped between said cap and cover members; said first actuator defining a first closed chamber with said cover member and having a movable end portion and an endless outer side wall extending between said movable end portion and said mounting flange, said side wall having at least one corrugation formed therein and being operable to change its length and hence the distance between said movable end portion and said cover member in response to pressure changes in said first chamber; a second flexible actuator received in the opening in said main body portion and having an outer peripheral mounting flange clamped between said cap member and said main body portion; said second actuator defining a second closed chamber with said shoulder and having a movable end portion, an outer side wall extending between said movable end portion and said outer mounting flange, an inner side wall extending between said movable end portion and said shoulder, an extension projecting into the opeNing of said cap member from said inner side wall, and an inner mounting flange on the end of said extension opposite said inner side wall; said inner mounting flange being clamped between said cap and cover members, and said inner and outer side walls of said second actuator each having at least one corrugation formed therein and being operable to change its length and hence the distance between the movable end portion and said shoulder in response to pressure changes in said second chamber.

Claim 14

Apparatus as claimed in claim 11 including complementary inclined surfaces formed on the outer end of said cap member and said cover member, said mounting flange of said first actuator and said inner mounting flange of said second actuator being clamped between said complementary inclined surfaces.

Claim 15

Apparatus as claimed in claim 11 wherein the corrugations in said side walls are inelastically deformable in response to pressure increases in said chambers causing the lengths of the actuator sidewalls to change, the inelastic deformation of said corrugations preventing the sidewalls from elastically rebounding to their original lengths when the pressure is subsequently reduced.

Claim 16

Apparatus as claimed in claim 11 including a stepped piston having a reduced portion projecting into engagement with the movable end portion of said first actuator and having a peripheral side surface engaged with the inner side wall of said second actuator, and said piston having an enlarged outer portion overlying the movable end portion of said second actuator.

Claim 17

Apparatus as claimed in claim 14 wherein the corrugations in said side walls are inelastically deformable in response to pressure increases in said chambers causing the lengths of the actuator sidewalls to change, the inelastic deformation of said corrugations preventing the sidewalls from elastically rebounding to their original lengths when the pressure is subsequently reduced.

Claim 18

Apparatus as claimed in claim 15 wherein the sidewalls of each of said actuators comprises metal and an outer layer of elastomeric material.

Claim 19

Apparatus as claimed in claim 14 wherein said main body portion comprises a disc brake caliper having a peripheral base portion and a leg portion extending therefrom, the opening in said main body portion being formed in said leg portion.

Claim 20

Apparatus as claimed in claim 17 including a rotor extending alongside said leg portion with said base portion overlying the peripheral edge of said rotor, and a brake shoe carried by said piston and movable into braking engagement with said rotor by expansion of either of said first or second chambers.

Claim 21

Apparatus as claimed in claim 18 including a source of brake fluid, an opening in said cap member connecting said source with said second chamber, and an opening in said cover member connecting said source with said first chamber.