# US 11,999,325 B2 · Friction member and master cylinder comprising same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,999,325 B2 - Document ID: US11999325B2 - Status: Granted - Kind: B2 - Application number: 17/287,624 - Filed: 2019-10-23 - Published: 2021-12-23 - Granted: 2024-06-04 - Earliest claimed: 2018-10-23 - Assignees: Hl Mando Corporation - Applicants: Hl Mando Corporation - Inventors: Joo Un Cho - Web page: https://patentgrep.com/patent/US11999325B2 ## CPC - B60T 11/165: {Single master cylinders for pressurised systems} - F16F 9/58: Stroke limiting stops, e.g. arranged on the piston rod outside the cylinder (F16F9/49 takes precedence) - B60T 11/18: Connection thereof to initiating means - F16D 65/097: Resilient means interposed between pads and supporting members {or other brake parts} - F16F 7/09: in dampers of the cylinder-and-piston type - B60T 8/4081: {Systems with stroke simulating devices for driver input (B60T8/4077 takes precedence)} - F16F 2222/04: Friction - B60T: VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL (electrodynamic brake systems for vehicle, in general B60L; brakes per se, i.e. devices where braking effect occurs, including ultimate brake actuators, F16D); ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES - F16F: SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION - F16D: COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES ## Abstract The present disclosure relates to a friction member and a master cylinder including the same. The master cylinder includes a cylinder body with a bore formed therein, a piston configured to move forward and backward in the bore and protrude a portion thereof from the cylinder body, a housing configured to surround the protruding portion of the piston and having a through hole formed therein such that an input rod connected to a brake pedal to press the piston is inserted, a friction member provided between the housing and the piston to increase a frictional force with the piston when the piston moves forward and backward, and a pedal simulator connected to the piston to provide a repulsive force to the brake pedal. ## Claims ### Claim 1 A master cylinder comprising: a cylinder body with a bore formed therein; a piston configured to move forward and backward in the bore and protrude a portion thereof from the cylinder body; a housing configured to surround the protruding portion of the piston and having a through hole formed therein such that an input rod connected to a brake pedal to press the piston is inserted; a friction member provided between the housing and the piston to increase a frictional force with the piston when the piston moves forward and backward; and a pedal simulator connected to the piston to provide a repulsive force to the brake pedal, wherein the friction member comprises: a body part having a hollow portion formed in a longitudinal direction; and an elastic pressing part formed on an inner circumferential surface of the body part and protruding to be in close contact with an outer circumferential surface of the piston, and the elastic pressing part and the outer circumferential surface of the piston come into close contact with a larger area when the piston moves backward than when the piston moves forward. ### Claim 2 (depends on 1) The master cylinder according to claim 1, wherein the pedal simulator is hydraulically connected to the bore and provided separately from the bore. ### Claim 3 (depends on 1) The master cylinder according to claim 1, wherein the elastic pressing part is configured to have a diameter smaller than a diameter of the piston in a predetermined section. ### Claim 4 A master cylinder comprising: a cylinder body with a bore formed therein; a piston configured to move forward and backward in the bore and protrude a portion thereof from the cylinder body; a housing installed on the cylinder body to surround a portion of the piston protruding from the cylinder body and having a through hole formed therein such that an input rod connected to a brake pedal to press the piston is inserted; and a friction member provided between the housing and the piston to increase a frictional force with the piston when the piston moves forward and backward, wherein the friction member comprises: a body part having a hollow portion formed in a longitudinal direction; and an elastic pressing part formed on an inner circumferential surface of the body part and protruding to be in close contact with an outer circumferential surface of the piston, and the elastic pressing part is configured such that an inner diameter of the body part gradually decreases in a backward movement direction of the piston. ### Claim 5 (depends on 4) The master cylinder according to claim 4, wherein the elastic pressing part is configured to have a diameter smaller than a diameter of the piston in a predetermined section. ### Claim 6 (depends on 5) The master cylinder according to claim 5, wherein a chamfer recessed inward from an end of the other side of the elastic pressing part is provided on the inner circumferential surface of an end of the body part. ### Claim 7 (depends on 4) The master cylinder according to claim 4, wherein a corrugated portion having an uneven shape is provided on an outer circumferential surface of the body part. ### Claim 8 (depends on 4) The master cylinder according to claim 4, wherein stoppers are configured to protrude at a regular interval along an outer circumferential surface of the other side of the body part. ### Claim 9 (depends on 8) The master cylinder according to claim 8, wherein a stopper groove into which each of the stoppers is fitted is provided at a position corresponding to each of the stoppers in the housing. ### Claim 10 A friction member, which is provided between a piston protruding from a master cylinder and a housing surrounding the piston, comprising: a body part having a hollow portion formed in a longitudinal direction; and an elastic pressing part protruding toward the piston from an inner circumferential surface of the body part, wherein the elastic pressing part is configured such that an inner diameter of the body part gradually decreases from one side of the body part to the other side, wherein stoppers are configured to protrude at a regular interval along an outer circumferential surface of the other side of the body part. ### Claim 11 (depends on 10) The friction member according to claim 10, wherein a chamfer recessed inward from an end of the other side of the elastic pressing part is provided on the inner circumferential surface of an end of the body part. ### Claim 12 (depends on 10) The friction member according to claim 10, wherein a corrugated portion having an uneven shape is provided on an outer circumferential surface of the body part. ### Claim 13 (depends on 10) The friction member according to claim 10, wherein the elastic pressing part is configured to have a diameter smaller than a diameter of the piston in a predetermined section.