Grease composition, machine component, and starter overrunning clutch

Patent metadata

Field	Value
Publication number	US-11713430-B2
Application number	US-202016794507-A
Country	US
Kind code	B2
Filing date	Feb 19, 2020
Priority date	Mar 11, 2016
Publication date	Aug 1, 2023
Grant date	Aug 1, 2023

Abstract

A silicone grease composition is disclosed. The grease composition contains a silicone oil and zinc dialkyldithiocarbamate as an extreme-pressure additive. The grease composition contains substantially no zinc dialkyldithiophosphate. The grease composition achieves high friction characteristics and wear characteristics. A method for transmitting torque of a clutch or a torque limiter mechanism is also disclosed. Moreover, a method for producing a clutch or a torque limiter mechanism is disclosed. The methods utilize the aforementioned grease composition.

First claim

The invention claimed is:

1. A method for transmitting torque of a clutch or a torque limiter mechanism, the method comprising:
enclosing a grease composition in a lubricating part of the clutch or the torque limiter mechanism;
wherein the enclosed grease composition consists of:
(A) a silicone oil having the general formula (I): R 1 a SiO (4-a)/2 in which each R 1 is independently selected from the group consisting of monovalent hydrocarbon groups, and a is from 1.8 to 2.2;
(B) zinc dialkyldithiocarbamate having the general formula (II): [R 5 2 N—C(═S)—S] 2 —Zn in which each R 5 is a methyl group; and
(C) an organic thickener selected from the group consisting of lithium soap and lithium complex soap;
wherein a content of the silicone oil (A) is from 60 mass % to 90 mass %, a content of the zinc dialkyldithiocarbamate (B) is from 7.5 mass % to 20 mass %, and a content of the organic thickener (C) is from 2.5 mass % to 20 mass %, each relative to the total amount of the enclosed grease composition, provided the total of components (A), (B), and (C) is 100 mass % of the enclosed grease composition.

2. The method according to claim 1 , wherein the silicone oil (A) has an aromatic hydrocarbon group per molecule.

3. The method according to claim 1 , wherein the clutch is an overrunning clutch and wherein the enclosed grease composition is enclosed in a clutch cam chamber formed by an outer clutch and an inner clutch.

4. The method according to claim 1 , wherein the organic thickener (C) is lithium stearate.

5. The method according to claim 4 , wherein the silicone oil (A) is of the general formula
Me 3 SiO(Me 2 SiO) I (R 2 R 3 SiO) m SiMe 3

where Me is a methyl group, R 2 is a methyl group or a phenyl group, R 3 is a phenyl group, I is 0 or a positive integer, and m is a positive integer.

6. The method according to claim 1 , wherein the silicone oil (A) is of the general formula
Me 3 SiO(Me 2 SiO) I (R 2 R 3 SiO) m SiMe 3

where Me is a methyl group, R 2 is a methyl group or a phenyl group, R 3 is a phenyl group, I is 0 or a positive integer, and m is a positive integer.

7. The method according to claim 1 , wherein the organic thickener (C) is a lithium soap.

8. The method according to claim 1 , wherein:
(i) the content of the silicone oil (A) is from 73.74 mass % to 77.14 mass %;
(ii) the content of the zinc dialkyldithiocarbamate (B) is from 9.25 mass % to 13.25 mass %;
(iii) the content of the organic thickener (C) is from 13.01 mass % to 13.61 mass %; or
(iv) each one of (i) to (iii); and
wherein each mass % is relative to 100 mass % of the enclosed grease composition.

9. The method according to claim 1 , further comprising:
providing the grease composition prior to the enclosing step, wherein the grease composition consists of components (A), (B), and (C).

10. The method according to claim 1 , further comprising:
providing an automobile starter, the automobile starter having the clutch or torque limiter mechanism.

11. The method according to claim 10 , wherein the clutch is an overrunning clutch and wherein the enclosed grease composition is enclosed in a clutch cam chamber formed by an outer clutch and an inner clutch.

12. The method according to claim 10 , further comprising:
powering the automobile starter, thereby transmitting torque of the clutch or torque limiter mechanism via the enclosed grease composition.

13. A method for transmitting torque of a clutch or a torque limiter mechanism, the method comprising:
providing an automobile starter, the automobile starter having the clutch or torque limiter mechanism;
providing a grease composition;
enclosing the grease composition in a lubricating part of the clutch or the torque limiter mechanism of the automobile starter; and
powering the automobile starter, thereby transmitting torque of the clutch or torque limiter mechanism via the enclosed grease composition;
wherein the enclosed grease composition consists of:
(A) a silicone oil having the general formula (I): R 1 a SiO (4-a)/2 in which each R 1 is independently selected from the group consisting of monovalent hydrocarbon groups, and a is from 1.8 to 2.2;
(B) zinc dialkyldithiocarbamate having the general formula (II): [R 5 2 N—C(═S)—S] 2 —Zn in which each R 5 is a methyl group; and
(C) an organic thickener selected from the group consisting of lithium soap and lithium complex soap;
wherein a content of the silicone oil (A) is from 60 mass % to 90 mass %, a content of the zinc dialkyldithiocarbamate (B) is from 7.5 mass % to 20 mass %, and a content of the organic thickener (C) is from 2.5 mass % to 20 mass %, each relative to the total amount of the enclosed grease composition, provided the total of components (A), (B), and (C) is 100 mass % of the enclosed grease composition.

14. The method according to claim 13 , wherein the clutch is an overrunning clutch and wherein the enclosed grease composition is enclosed in a clutch cam chamber formed by an outer clutch and an inner clutch.

15. The method according to claim 13 , wherein the organic thickener (C) is lithium stearate.

16. The method according to claim 15 , wherein the silicone oil (A) is of the general formula
Me 3 SiO(Me 2 SiO) I (R 2 R 3 SiO) m SiMe 3

where Me is a methyl group, R 2 is a methyl group or a phenyl group, R 3 is a phenyl group, I is 0 or a positive integer, and m is a positive integer.

17. The method according to claim 13 , wherein:
(i) the content of the silicone oil (A) is from 73.74 mass % to 77.14 mass %;
(ii) the content of the zinc dialkyldithiocarbamate (B) is from 9.25 mass % to 13.25 mass %; and
(iii) the content of the organic thickener (C) is from 13.01 mass % to 13.61 mass %;
wherein each mass % is relative to 100 mass % of the enclosed grease composition.

18. The method according to claim 13 , consisting of the providing, enclosing, and powering steps.

Assignees

• Denso Corp
• Dow Corning Toray Co Ltd
• Dupont Toray Specialty Materials Kk

Inventors

• Fukushima Yoshinori
• Hasegawa Youichi
• MASAMURA Yuji
• Mori Makoto
• Sakakibara Koji

Classifications

• C10M107/50 Primary

  containing silicon · CPC title

• C10M117/02

  having only one carboxyl group bound to an acyclic carbon atom, cycloaliphatic carbon atom or hydrogen · CPC title

• C10M135/18

  thiocarbamic type, e.g. containing the groups [IMAGE cpc-sch-C10M-1027.gif] · CPC title

• C10M169/04 Primary

  Mixtures of base-materials and additives · CPC title

• C10M169/06

  Mixtures of thickeners and additives · CPC title