Lubricating oil composition for diesel engine

Abstract

The invention provides lubricant compositions for diesel engines having a regenerative DPF, which prolong life of the DPF by inhibiting accumulation of components depositable on DPF inner walls, diesel engine system shaving a regenerative DPF with prolonged life, and a method for inhibiting accumulation of components depositing on the DPF in the system. The present composition is for diesel engines having a regenerative DPF and running on diesel fuel with <10 mass ppm sulfur, contains a base oil and additives including (A) metal detergent, (B) ashless dispersant, and (C) phosphorus-based anti-wear agent, and satisfies the conditions of a sulfated ash content of 0.4-2 mass %, an atomic ratio of metal from component (A) to the total phosphorus of 0.2-3, an atomic ratio of the total boron to metal from component (A) of 0.2-2, and an atomic ratio of the total sulfur to metal from component (A) of 0-4.

Description

FIELD OF ART [0001] The present invention relates to a lubricant composition for a diesel engine equipped with a regenerative DPF, a diesel engine system equipped with a regenerative accumulation of depositing components on a regenerative DPF in such a system. BACKGROUND ART [0002] Emission regulations have become more and more strict every year over the world in light of environmental problems. In particular, it is imperative to reduce NOx and particulate matters (PM) in the exhaust gas from diesel engines. For reducing such exhaust gas, combustion improvement technologies, such as high-pressure injection and exhaust gas recirculation (EGR) systems, or exhaust gas treatment technologies, such as oxidation catalysts, diesel particulate filters (DPF), and NOx storage reduction catalysts, have been under development. [0003] DPFs, which are used for capturing and removing PM in exhaust gas with a filter, have various structures. For example, a wall-flow type DPF has a structure wherein...

AI Technical Summary

Benefits of technology

"The present invention provides a lubricant composition for a diesel engine that can prolong the life of a regenerative DPF by inhibiting the accumulation of components that are easily deposited on its inner walls. This is achieved by using a lubricant composition that contains a metal detergent, an ashless dispersant, and a phosphorus-based anti-wear agent, and that satisfies specific conditions. The use of this lubricant composition results in a reduction of ash content, an atomic ratio of metal to phosphorus, an atomic ratio of the total boron to metal, and an atomic ratio of the total sulfur to metal. The invention also provides a diesel engine system equipped with a regenerative DPF and using this lubricant composition, as well as a method for inhibiting accumulation of a depositing component on a DPF and facilitating removal of accumulated components."

Problems solved by technology

However, this type of a DPF has problems in that the captured PM accumulates to increase pressure loss, lower engine power, or deteriorate fuel efficiency.

However, it has been revealed that deposition of ash on a DPF cannot be inhibited merely by lowering the ash content.

Such deposited ash cannot be removed easily by back flushing operation by means of air blow in the regeneration.

The deposited ash has severe impact on the life span of a DPF, particularly of a continuous regenerative DPF.

However, details of the depositing ash formation has not been fully investigated so far, and little report has been made to date on actual evaluation and optimization of the impact of fuel and lubricant on diesel engines equipped with a regenerative DPF.

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