US 2012/0205209 A1Published application

Drum brake type parking brake apparatus

OwnerHaruo Tsuzuku, Hiroyasu Ishikawa +3inventors

InventorsHaruo Tsuzuku, Hiroyasu Ishikawa, Hiroshi Ikegami, Hideki Kakizaki, Toshifumi Maehara

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Abstract

A joining link, a strut, and first and second expansion levers constitute an expansion and contraction device. At the time of the braking, the proximal end portion of both of the expansion levers are mutually pressed from the opposite sides by first and second pressing members constituting a driving device. The reaction due to the braking is offset by the joining link portion, whereby a large force is not applied to the back plate or the like.

Claims6

Dependent claims

A drum brake type parking brake apparatus comprising:

a back plate that is supported and fixed to a constitution member of a suspension device;
a pair of brake shoes that is fixed in two positions of opposite sides in a diameter direction of the back plate so as to be displaceable in the diameter direction of the back plate;
a drum that is provided in a state of covering both of the brake shoes and is rotated with vehicle wheels;
an expansion and contraction device that is provided between inner peripheral edges of webs constituting both of the brake shoes so as to expand or contract a gap between both of the brake shoes;
and a driving device for driving the expansion and contraction device,
wherein the expansion and contraction device includes a joining link, a strut, and first and second expansion levers, the joining link is disposed in a direction of expanding or contracting both of the brake shoes, the first expansion lever is pivotally supported on an end portion of a side of one brake shoe of the joining link at a portion near a middle portion distal end thereof, the distal end portion is engaged with the web of one brake shoe so that the distal end portion presses the web in an outer direction of the diameter direction, the second expansion lever is pivotally supported on an end portion of a side opposite to the one brake shoe of the joining link at a portion near a middle portion distal end thereof, the distal end portion is pivotally supported on the proximal end portion of the strut, and the distal end portion of the strut is engaged with the web of the other brake shoe of both of the brake shoes so that the distal end portion presses the web in the outer direction of the diameter direction,
wherein the driving device includes a pair of pressing members that is distantly moved in a disposition direction of the joining link in a state of mutually interposing the proximal end portions of the first and second expansion levers from opposite sides, and a driving source for expanding or contracting the gap between both of pressing members, and
wherein a distance from a center of a pivot portion between the end portion of the joining link and a portion near the middle portion distal end of the first expansion lever to an engagement portion of the distal end portion of the first expansion lever with the inner peripheral edge of the web of the one brake shoe is smaller than a distance to an engagement portion of the first expansion lever with the pressing member, and a distance from a center of a pivot portion between the end portion of the joining link and a portion near the middle portion distal end of the second expansion lever to a center of the pivot portion between the distal end portion of the second expansion lever and the proximal end portion of the strut is smaller than a distance to an engagement portion of the second expansion lever with the pressing member.

5 more elements

Dependencies are inferred from the claim text.

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Abstract

A drum brake type parking brake apparatus comprising:

a back plate that is supported and fixed to a constitution member of a suspension device;
a pair of brake shoes that is fixed in two positions of opposite sides in a diameter direction of the back plate so as to be displaceable in the diameter direction of the back plate;
a drum that is provided in a state of covering both of the brake shoes and is rotated with vehicle wheels;
an expansion and contraction device that is provided between inner peripheral edges of webs constituting both of the brake shoes so as to expand or contract a gap between both of the brake shoes;
and a driving device for driving the expansion and contraction device,
wherein the expansion and contraction device includes a joining link, a strut, and first and second expansion levers, the joining link is disposed in a direction of expanding or contracting both of the brake shoes, the first expansion lever is pivotally supported on an end portion of a side of one brake shoe of the joining link at a portion near a middle portion distal end thereof, the distal end portion is engaged with the web of one brake shoe so that the distal end portion presses the web in an outer direction of the diameter direction, the second expansion lever is pivotally supported on an end portion of a side opposite to the one brake shoe of the joining link at a portion near a middle portion distal end thereof, the distal end portion is pivotally supported on the proximal end portion of the strut, and the distal end portion of the strut is engaged with the web of the other brake shoe of both of the brake shoes so that the distal end portion presses the web in the outer direction of the diameter direction,
wherein the driving device includes a pair of pressing members that is distantly moved in a disposition direction of the joining link in a state of mutually interposing the proximal end portions of the first and second expansion levers from opposite sides, and a driving source for expanding or contracting the gap between both of pressing members, and
wherein a distance from a center of a pivot portion between the end portion of the joining link and a portion near the middle portion distal end of the first expansion lever to an engagement portion of the distal end portion of the first expansion lever with the inner peripheral edge of the web of the one brake shoe is smaller than a distance to an engagement portion of the first expansion lever with the pressing member, and a distance from a center of a pivot portion between the end portion of the joining link and a portion near the middle portion distal end of the second expansion lever to a center of the pivot portion between the distal end portion of the second expansion lever and the proximal end portion of the strut is smaller than a distance to an engagement portion of the second expansion lever with the pressing member.

5 more elements