1. A lubricating oil composition comprising a major amount of an oil of a Group II or higher base oil of lubricating viscosity and a minor amount of a polymer composition comprising at least a first polymer that is an ethylene \u03b1-olefin copolymer comprising no greater than 66 mass % of units derived from ethylene; and a second polymer comprising a linear diblock copolymer comprising at least one block derived primarily from a vinyl aromatic hydrocarbon monomer, and at least one block derived primarily from diene monomer.
2. A lubricating oil composition as claimed in claim 1, wherein the first polymer and the second polymer are present in a mass % ratio of from about 80:20 to about 20:80.
3. A lubricating oil composition as claimed in claim 2, wherein said ethylene \u03b1-olefin copolymer is an ethylene-propylene copolymer and said linear diblock copolymer is at least one diblock copolymer comprising at least one polystyrene block, and at least one block derived from isoprene, butadiene, or a mixture thereof.
4. A lubricating oil composition as claimed in claim 3, wherein said ethylene \u03b1-olefin copolymer is an ethylene-propylene copolymer and said linear diblock copolymer is at least one diblock copolymer selected from the group consisting of hydrogenated styrenebutadiene block copolymers and hydrogenated styreneisoprene block copolymers.
5. A lubricating oil composition as claimed in claim 3, wherein said ethylene-propylene copolymer comprises from about 20 to about 66 mass % of units derived from ethylene.
6. A lubricating oil composition as claimed in claim 3, wherein said ethylene-propylene copolymer has a Shear Stability Index (SSI) value of from about 20% to about 50% (30 cycles), and the polydiene block of the diblock copolymer comprises from about 40 mass % to 90 mass % derived from isoprene and from about 10 mass % to about 60 mass % derived from butadiene.
7. A lubricating oil composition as claimed in claim 1, wherein said base oil of lubricating viscosity has a saturates content of at least about 80.
8. A lubricating oil composition as claimed in claim 1, containing less than about 30 mass % of Group I base oil.
9. A lubricating oil composition as claimed in claim 1, further comprising a nitrogenous dispersant derived from a polyalkene having a number average molecular weight (Mn) of greater than about 1500, wherein said base oil of lubricating viscosity has a saturates content of at least about 80%, and wherein said lubricating oil composition contains less than about 0.4 mass % of sulfur, less than about 0.12 mass % phosphorus and less than about 1.2 mass % of sulfated ash.
10. A lubricating oil composition as claimed in claim 1, further comprising a metal-containing detergent.
11. A lubricating oil composition as claimed in claim 10, wherein the metal-containing detergent comprises less than 40 mole % of a metal salt of an aromatic carboxylic acid, based on the moles of the metal salts of organic acids in the detergent composition.
12. A lubricating oil composition as claimed in claim 11, wherein the metal-containing detergent is present in the composition in an amount, based on surfactant content, less than 5 millimoles of surfactant per kilogram of the oil composition (mmolkg).
13. A lubricating oil composition as claimed in claim 1, which contains no metal-containing detergent.
14. A method of operating an internal combustion engine, said method comprising lubricating said engine with a lubricating oil composition as claimed in claim 1, and operating the lubricating engine.
15. A method of operating an internal combustion engine, said method comprising lubricating said engine with a lubricating oil composition as claimed in claim 9, and operating the lubricating engine.
16. The method as claimed in claim 15, wherein said engine is a heavy duty diesel (HDD) engine.
17. A method of improving the soot-handling properties of a lubricating oil composition for the lubrication of an internal combustion engine, which method comprises formulating said lubricating oil composition with a polymer composition comprising at least a first polymer that is an ethylene \u03b1-olefin copolymer comprising no greater than 66 mass % of units derived from ethylene; and a second polymer comprising a linear diblock copolymer comprising at least one block derived primarily from a vinyl aromatic hydrocarbon monomer, and at least one block derived primarily from diene monomer.
18. The method as claimed in claim 17, wherein said lubricating oil composition is further formulated with a nitrogenous dispersant derived from a polyalkene having a number average molecular weight (Mn) of greater than about 1500, and a base oil of lubricating viscosity having a saturates content of at least about 80%, and wherein said lubricating oil composition contains less than about 0.4 mass % of sulfur, less than about 0.12 mass % phosphorus and less than about 1.2 mass % of sulfated ash.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An optical module comprising:
a light source;
a variable transmissivity member that is disposed in a light path of light emitted from the light source with a spacing of a first distance from the light source, the variable transmissivity member having transmissivity that increases as temperature rises;
a partial reflection member that is disposed on the light path of the light emitted from the light source with a spacing of a second distance from the light source, the second distance being larger than the first distance, the partial reflection member reflecting a first light component and transmitting a second light component of light that has been transmitted through the variable transmissivity member;
a light quantity monitor that is disposed in a light path of the first light component; and
an optical fiber that receives the second light component, the variable transmissivity member being disposed so as that the light path of the light emitted and the light path of the first light component pass through, and the light quantity monitor detecting quantity of the first light component,
wherein a first temperature inclination representing transmissivity variation with respect to temperature variation in the partial reflection member is smaller than a second temperature inclination representing transmissivity variation with respect to temperature variation in the variable transmissivity member.
2. The optical module according to claim 1, wherein a wavelength of the light emitted increases as temperature increases.
3. The optical module according to claim 2, wherein the light source is a vertical cavity surface emitting laser.
4. The optical module according to claim 1, wherein the transmissivity of the variable transmissivity member varies with variation in a wavelength of incident light.
5. The optical module according to claim 4, wherein the transmissivity of the variable transmissivity member increases as the wavelength of the incident light increases.
6. The optical module according to claim 1, wherein transmissivity of the partial reflection member is larger than transmissivity of the variable transmissivity member.
7. An optical communications device comprising the optical module according to claim 1.