# US 9,038,792 B2 · Shock absorber > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,038,792 B2 - Document ID: US9038792B2 - Status: Granted - Kind: B2 - Application number: 13/818,911 - Filed: 2011-11-29 - Published: 2013-06-20 - Granted: 2015-05-26 - Earliest claimed: 2010-12-02 - Assignees: Kayaba Industry Co., Ltd. - Applicants: Masashi Sumida - Inventors: Masashi Sumida - Web page: https://patentgrep.com/patent/US9038792B2 ## CPC - F16F 9/18: with a closed cylinder and a piston separating two or more working spaces therein - B62K 25/08: for front wheel - F16F 9/06: using both gas and liquid {(F16F9/486 take precedence; self-pumping fluid springs B60G17/044)} - F16F 9/064: {Units characterised by the location or shape of the expansion chamber (F16F9/068, F16F9/08 take precedence)} - F16F 9/368: {Sealings in pistons} - B62K 2025/048: {with suspension manual adjustment details} - F16F: SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION - B62K: CYCLES; CYCLE FRAMES; CYCLE STEERING DEVICES; RIDER-OPERATED TERMINAL CONTROLS SPECIALLY ADAPTED FOR CYCLES; CYCLE AXLE SUSPENSIONS; CYCLE SIDECARS, FORECARS, OR THE LIKE ## Abstract A shock absorber includes a shock absorber main body composed of a vehicle-body side tube and a wheel side tube and formed with a lubrication clearance, a damper including a cylinder, a piston which partitions the interior of the cylinder into two working chambers, and a rod, a reservoir chamber composed of an air chamber and a working fluid chamber, a partition wall member for partitioning the working fluid chamber into an upper working fluid chamber and a lower working fluid chamber, a flow path having a check valve for permitting only a movement of the working fluid from the upper working fluid chamber to the lower working fluid chamber, and a communication path for allowing communication between the lower working fluid chamber and the lubrication clearance. A cross-sectional area of the lubrication clearance and that of the rod are different. ## Claims ### Claim 1 A shock absorber, comprising: a shock absorber main body composed of a vehicle-body side tube and a wheel side tube to be slidably inserted into the vehicle-body side tube via a pair of upper and lower bearings, the upper bearing being mounted on the outer periphery of the wheel side tube, the lower bearing being mounted on the inner periphery of the vehicle-body side tube and a lubrication clearance being formed between the pair of upper and lower bearings; a damper including a cylinder which stands in an axial center part of the wheel side tube and stores a working fluid, a piston which is held in sliding contact with the inner periphery of the cylinder and partitions the interior of the cylinder into two working chambers, and a rod which intrudes into and exits from the cylinder via the piston; a reservoir chamber formed between the shock absorber main body and the damper, composed of an air chamber and a working fluid chamber and configured to compensate for the working fluid that becomes excessive and insufficient in the damper; a partition wall member partitioning the working fluid chamber into an upper working fluid chamber and a lower working fluid chamber; a flow path formed in the partition wall member and having a check valve to permit only a movement of the working fluid from the upper working fluid chamber to the lower working fluid chamber; and a communication path allowing communication between the lower working fluid chamber and the lubrication clearance; wherein a cross-sectional area of the lubrication clearance and that of the rod are different. ### Claim 2 (depends on 1) The shock absorber according to claim 1, wherein the cross-sectional area of the lubrication clearance is smaller than that of the rod. ### Claim 3 (depends on 1) The shock absorber according to claim 1, wherein the cross-sectional area of the lubrication clearance is larger than that of the rod. ### Claim 4 (depends on 1) The shock absorber according to claim 1, further comprising a base member provided at a bottom part of the cylinder, wherein: the two working chambers partitioned by the piston are an extension side working chamber formed at the rod side and a compression side working chamber formed at the piston side; and the compression side working chamber and the lower working fluid chamber communicate via the base member provided at the bottom part of the cylinder. ### Claim 5 (depends on 1) The shock absorber according to claim 1, wherein the partition wall member is an annular rod guide mounted on a head part of the cylinder. ### Claim 6 (depends on 5) The shock absorber according to claim 5, wherein the rod guide includes a large-diameter portion, the outer periphery of which is formed to have a larger diameter than that of the cylinder, and the flow path is formed between the outer periphery of the large-diameter portion and the wheel side tube. ### Claim 7 (depends on 6) The shock absorber according to claim 6, wherein: an annular groove having a C-shaped cross section is formed in the outer periphery of the large-diameter portion and an annular check valve is loosely fitted in an outer peripheral of the annular groove; the annular groove is formed by a vertical surface facing the inner periphery of the annular check valve and an upper surface and a lower surface formed to face each other at the upper and lower ends of the vertical surface; and the annular check valve is formed to have an axial length shorter than a length of the vertical surface, the outer periphery of the annular check valve is held in sliding contact with the inner periphery of the wheel side tube, a radially formed cut is provided in the lower surface of the annular check valve, and a clearance flow path is formed between the inner periphery of the annular check valve and the vertical surface. ### Claim 8 (depends on 6) The shock absorber according to claim 6, wherein: an annular groove having a C-shaped cross section is formed in the outer periphery of the large-diameter portion, and the check valve is an annular check valve and is loosely fitted in an outer peripheral part of the annular groove; the annular groove is formed by a vertical surface facing an inner periphery of the check valve and an upper surface and a lower surface formed to face each other at upper and lower ends of the vertical surface; the check valve is formed to have an axial length shorter than a length of the vertical surface, an outer periphery of the check valve is held in sliding contact with an inner periphery of the wheel side tube, a radially formed cut is provided in a lower surface of the check valve, and a clearance flow path is formed between the inner periphery of the check valve and the vertical surface. ### Claim 9 (depends on 1) The shock absorber according to claim 1, wherein the lubrication clearance has an upper end at the upper bearing, further wherein the working fluid is in the lubrication clearance, and the working fluid in the lubrication clearance directly contacts the upper bearing based upon a difference between a pressure of the upper working fluid chamber and a pressure of the lower working fluid chamber. ### Claim 10 (depends on 9) The shock absorber according to claim 9, wherein the working fluid in the lubrication clearance passes by the upper bearing and into the air chamber based upon the difference. ### Claim 11 (depends on 9) The shock absorber according to claim 9, wherein the working fluid in the lubrication clearance passes by the upper bearing, into the air chamber and then into the upper working fluid chamber based upon the difference. ### Claim 12 (depends on 9) The shock absorber according to claim 9, wherein the working fluid in the lubrication clearance passes by the upper bearing, and then into the upper working fluid chamber based upon the difference. ### Claim 13 A shock absorber, comprising: a shock absorber main body including a vehicle-body side tube, and a pair of upper and lower bearings, the lower bearing being mounted on an inner periphery of the vehicle-body side tube, a wheel side tube slidably inserted into the vehicle-body side tube via the pair of upper and lower bearings, the upper bearing being mounted on an outer periphery of the wheel side tube, a lubrication clearance being formed between the pair of upper and lower bearings; a damper including a cylinder which stands in an axial center part of the wheel side tube and stores a working fluid, a piston slidable along an inner periphery of the cylinder, the piston partitioning an interior of the cylinder into two working chambers, and a rod which intrudes into and exits from the cylinder via the piston; a reservoir chamber formed between the shock absorber main body and the damper, the reservoir chamber being composed of an air chamber and a working fluid chamber and configured to compensate for the working fluid when the working fluid becomes excessive and insufficient in the damper; a partition wall member partitioning the working fluid chamber into an upper working fluid chamber and a lower working fluid chamber; a flow path formed in the partition wall member and allowing for communication between the upper working fluid chamber and the lower working fluid chamber; a check valve in the flow path to permit only a movement of the working fluid from the upper working fluid chamber to the lower working fluid chamber; and a communication path allowing communication between the lower working fluid chamber and the lubrication clearance, wherein a cross-sectional area of the lubrication clearance and that of the rod are different. ### Claim 14 (depends on 13) The shock absorber according to claim 13, wherein the lubrication clearance has an upper end at the upper bearing, further wherein the working fluid is in the lubrication clearance, and the working fluid in the lubrication clearance directly contacts the upper bearing based upon a difference between a pressure of the upper working fluid chamber and a pressure of the lower working fluid chamber. ### Claim 15 (depends on 14) The shock absorber according to claim 14, wherein the working fluid in the lubrication clearance passes by the upper bearing and into the air chamber based upon the difference. ### Claim 16 (depends on 14) The shock absorber according to claim 14, wherein the working fluid in the lubrication clearance passes by the upper bearing, into the air chamber and then into the upper working fluid chamber based upon the difference. ### Claim 17 (depends on 14) The shock absorber according to claim 14, wherein the working fluid in the lubrication clearance passes by the upper bearing, and then into the upper working fluid chamber based upon the difference. ### Claim 18 (depends on 13) The shock absorber according to claim 13, wherein the partition wall member is an annular rod guide mounted on a head part of the cylinder. ### Claim 19 (depends on 18) The shock absorber according to claim 18, wherein the rod guide includes a large-diameter portion, the outer periphery of which is formed to have a larger diameter than that of the cylinder, and the flow path is formed between the outer periphery of the large-diameter portion and the wheel side tube. ### Claim 20 (depends on 19) The shock absorber according to claim 19, wherein: an annular groove having a C-shaped cross section is formed in the outer periphery of the large-diameter portion, and the check valve is an annular check valve and is loosely fitted in an outer peripheral of the annular groove; the annular groove is formed by a vertical surface facing an inner periphery of the check valve and an upper surface and a lower surface formed to face each other at upper and lower ends of the vertical surface; the check valve is formed to have an axial length shorter than a length of the vertical surface, an outer periphery of the check valve is held in sliding contact with an inner periphery of the wheel side tube, a radially formed cut is provided in a lower surface of the check valve, and a clearance flow path is formed between the inner periphery of the check valve and the vertical surface.