Grease composition and steering gear device

A grease composition with trimellitic acid ester, poly-α-olefin, lithium 12-hydroxystearate, lithium stearate, and molybdenum dialkyldithiocarbamate addresses lubrication issues in steering gear devices, enhancing wear resistance and maintaining steering performance by forming a tribo-film on friction surfaces.

JP7878334B2Active Publication Date: 2026-06-23JTEKT CORP
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Patent Information

Application Number
JP2023578360
Authority / Receiving Office
JP · JP
Patent Type
Patents
Current Assignee / Owner
Priority Date
2022-02-01
Filing Date
2022-06-17
Publication Date
2026-06-23
Estimated Expiration
2042-06-17

AI Technical Summary

Technical Problem

Existing grease compositions for steering gear devices fail to adequately lubricate the meshing portions between rack and pinion teeth and the sliding contact areas between the rack shaft and the rack guide mechanism, leading to wear and poor lubrication, especially when the rack guide mechanism is made of resin like PTFE.

Method used

A grease composition comprising trimellitic acid ester, poly-α-olefin, lithium 12-hydroxystearate, lithium stearate, and molybdenum dialkyldithiocarbamate, which forms a tribo-reaction film to enhance lubrication and suppress wear on friction surfaces, including those made of steel and resin.

Benefits of technology

The grease composition effectively lubricates both meshing and sliding contact areas, reducing wear and maintaining steering performance over time by forming a stable tribo-film on friction surfaces.

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Abstract

Provided is a grease composition comprising a base oil, a thickener, and an extreme pressure additive, wherein the base oil includes trimellitate ester and poly-α-olefin, the content of the trimellitate ester is 10.0-60.0 mass% with respect to the total amount of the trimellitate ester and the poly-α-olefin, the thickener includes lithium 12-hydroxystearate and lithium stearate, the content of the lithium 12-hydroxystearate is 5.0-95.0 mass% with respect to the total amount of the lithium 12-hydroxystearate and the lithium stearate, the extreme pressure additive includes molybdenum dialkyldithiocarbamate, and the content of the molybdenum dialkyldithiocarbamate is 0.6-16.0 mass% with respect to the total amount of the trimellitate ester, the poly-α-olefin, the lithium 12-hydroxystearate, the lithium stearate, and molybdenum dialkyldithiocarbamate.
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