# US 11,999,315 B2 · Safety belt system and method for determining the belt strap extension by means of a safety belt system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,999,315 B2 - Document ID: US11999315B2 - Status: Granted - Kind: B2 - Application number: 17/056,780 - Filed: 2019-06-03 - Published: 2021-04-29 - Granted: 2024-06-04 - Earliest claimed: 2018-06-07 - Assignees: ZF Automotive Germany GmbH - Applicants: Zf Automotive Germany GmbH - Inventors: Wolfgang Holbein; David Reich - Web page: https://patentgrep.com/patent/US11999315B2 ## CPC - B60R 22/48: Control systems, alarms, or interlock systems, for the correct application of the belt or harness - B60R 2022/4825: {for sensing amount of belt winded on retractor} - B60R: VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR ## Abstract A seatbelt system for a vehicle comprises a webbing (28), a belt retractor, a belt reel (16) and a belt reel angle sensor (22) having a first gearwheel assembly (32) and a second gearwheel assembly (36). The belt reel angle sensor (22) includes a multi-stage gearing (58) having a first gear stage with a first reduction ratio and a second gear stage with a second reduction ratio. The belt reel angle sensor (22) further comprises a rotation angle sensor (64) and a rotation angle transmitter (34) associated with the rotation angle sensor (64) as well as a reference signal sensor (68) and a reference signal transmitter (38) associated with the reference signal sensor (68). The rotation angle transmitter (34) is associated with the first gearwheel assembly (32) and the reference signal transmitter (38) is associated with the second gearwheel assembly (36). Relative to the reference signal sensor (68), the second gearwheel assembly (36) has a parking position, a base position and a reference position at which the reference signal transmitter (38) generates a reference signal in the reference signal sensor (68). Moreover, a method for determining the webbing extension by means of such seatbelt system is described. ## Claims ### Claim 1 A seatbelt system (10) for a vehicle, comprising a controller (26), a belt webbing (28) and a belt retractor (12) which includes a belt reel (16) arranged for winding up the belt webbing (28) and a belt reel angle sensor (22) connected to the controller (26) to transmit signals, wherein the belt reel angle sensor (22) includes a first gearwheel assembly (32) having a first gearwheel (40) and a second gearwheel (42) coupled to the first gearwheel (40) as well as a second gearwheel assembly (36) having teeth (48), wherein a pinion (30) associated with the belt reel (16) is coupled to the first gearwheel (40) such that a first gear stage (60) having a first reduction ratio is formed, wherein the second gearwheel (42) is coupled to the teeth (48) such that a second gear stage (62) having a second reduction ratio is formed, wherein the belt reel angle sensor (22) comprises a rotation angle sensor (64) and a rotation angle transmitter (34) associated with the rotation angle sensor (64) as well as a reference signal sensor (68) and a reference signal transmitter (38) associated with the reference signal sensor (68), wherein the rotation angle transmitter (34) is associated with the first gearwheel assembly (32) and the reference signal transmitter (38) is associated with the second gearwheel assembly (36), wherein, relative to the reference signal sensor (68), the second gearwheel assembly (36) has a parking position, a base position and a reference position at which the reference signal transmitter (38) generates a reference signal in the reference signal sensor (68). ### Claim 2 (depends on 1) The seatbelt system according to claim 1, wherein the reference position is disposed following the parking position, especially between the parking position and the base position. ### Claim 3 (depends on 1) The seatbelt system according to claim 1, wherein the second gearwheel assembly (36) is rotatably supported relative to the reference signal sensor (68), wherein the angle (α) between the parking position and the reference position and/or the base position is less than 180°. ### Claim 4 (depends on 3) The seatbelt system according to claim 3, wherein the angle (α) between the parking position and the reference position and/or the base position is less than 60°. ### Claim 5 (depends on 1) The seatbelt system according to claim 1, wherein the first reduction ratio is lower than the second reduction ratio. ### Claim 6 (depends on 1) The seatbelt system according to claim 1, wherein the first reduction ratio amounts to at least 1/10. ### Claim 7 (depends on 1) The seatbelt system according to claim 1, wherein the second reduction ratio amounts to at most ½. ### Claim 8 (depends on 1) The seatbelt system according to claim 1, wherein the reduction ratio of the multi-stage gearing (58) formed by the first gear stage (60) and the second gear stage (62) amounts to at most 1/10. ### Claim 9 (depends on 1) The seatbelt system according to claim 1, wherein the belt retractor (12) comprises a locking side assembly (20), the belt reel angle sensor (22) being integrated in the locking side assembly (20). ### Claim 10 (depends on 1) The seatbelt system according to claim 1, wherein the seatbelt system (10) is configured such that the webbing extension between the parking position and a fully extended position at which the webbing (28) is completely extended results in a rotation angle of the belt reel (16) that is more than 360°. ### Claim 11 (depends on 1) A method for determining the webbing extension by means of a seatbelt system (10) according to claim 1, comprising the following steps: the reference signal is used to calibrate the belt reel angle sensor (22) by assigning a reference value to the belt reel (16) at the reference position, and the change of position of the belt reel (16) relative to the reference position is detected by means of the rotation angle sensor (64). ### Claim 12 (depends on 1) The seatbelt system according to claim 1, wherein the reference position is disposed between the parking position and the base position. ### Claim 13 (depends on 1) The seatbelt system according to claim 1, wherein the first reduction ratio amounts to at least ⅓. ### Claim 14 (depends on 1) The seatbelt system according to claim 1, wherein the first reduction ratio amounts to at least ⅕. ### Claim 15 (depends on 1) The seatbelt system according to claim 1, wherein the second reduction ratio amounts to at most ⅓. ### Claim 16 (depends on 1) The seatbelt system according to claim 1, wherein the second reduction ratio amounts to at most ¼. ### Claim 17 (depends on 1) The seatbelt system according to claim 1, wherein the reduction ratio of the multi-stage gearing (58) formed by the first gear stage (60) and the second gear stage (62) amounts to at most 1/15. ### Claim 18 (depends on 1) The seatbelt system according to claim 1, wherein the reduction ratio of the multi-stage gearing (58) formed by the first gear stage (60) and the second gear stage (62) amounts to at most 1/20. ### Claim 19 (depends on 1) The seatbelt system according to claim 1, wherein the seatbelt system (10) is configured such that the webbing extension between the parking position and a fully extended position at which the webbing (28) is completely extended results in a rotation angle of the belt reel (16) that is more than 1800°. ### Claim 20 (depends on 1) The seatbelt system according to claim 1, wherein the seatbelt system (10) is configured such that the webbing extension between the parking position and a fully extended position at which the webbing (28) is completely extended results in a rotation angle of the belt reel (16) that is more than 3600°.