Piston seal and disc brake using the piston seal
AssigneesNissin Kogyo Co., Ltd., Fukoku Co., Ltd.
InventorsToru Noguchi, Kazuhito Kawata, Takashi Wanibuchi, Koichi Arita
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Abstract
A piston seal of a disc brake can stabilize the amount of rollback of a piston by reducing thermal expansion and a decrease in modulus of elasticity of the piston seal caused by an increase in temperature, thereby preventing a driver from feeling that the brake operation is unnatural. The piston seal is formed of a rubber composition in which at least 100 parts by weight or more of carbon black is added to 100 parts by weight of ethylene propylene rubber.
Claims4
A piston seal used for a caliper body for a disc brake,
- wherein the piston seal fluid-tightly and slidably maintains a piston in a cylinder bore, the piston sliding inside the cylinder bore, and the piston is rolled back,
- wherein the piston seal is formed of an ethylene propylene rubber composition comprising at least 100 parts carbon black per hundred parts rubber, and
- wherein the rubber composition has a dynamic modulus of elasticity of 12 MPa or more both at 10 Hz and 30° C., and at 10 Hz and 150° C.
A piston seal used for a caliper body for a disc brake,
- wherein the piston seal fluid-tightly and slidably maintains a piston in a cylinder bore, the piston sliding inside the cylinder bore, and the piston is rolled back,
- wherein the piston seal is formed of an ethylene propylene rubber composition comprising at least 100 parts carbon black per hundred parts rubber, and
- wherein the rubber composition has a rate of change in dynamic modulus of elasticity caused by an increase in temperature from 30° C. to 150° C. within ±25%.
Dependencies are inferred from the claim text.