Engine oil degradation-estimating device and device for estimating antioxidant performance of engine oil

A device for estimating an antioxidant performance of engine oil, which is used as an indicator for determining degradation of engine oil, comprising:

• fuel concentration-acquiring means for acquiring a concentration of fuel in the engine oil;
• antioxidant performance-estimating means for estimating an antioxidant performance of engine oil, based on the acquired concentration of fuel;
• oil temperature-acquiring means for acquiring a temperature of engine oil;
• and
• NOx concentration-acquiring means for acquiring a NOx concentration within a crankcase of the engine,
• wherein said antioxidant performance-estimating means estimates the antioxidant performance further based on the acquired oil temperature and NOx concentration;
• wherein said antioxidant performance-estimating means comprises:
• first antioxidant performance-estimating means for estimating an antioxidant performance of an antioxidant contained in the engine oil as a first antioxidant performance;
• and
• second antioxidant performance-estimating means for estimating an antioxidant performance of a peroxide decomposer contained in the engine oil as a second antioxidant performance, and calculates the antioxidant performance based on the estimated first antioxidant performance and second antioxidant performance;
• wherein said first antioxidant performance-estimating means calculates a rate of change in oxidation induction time corresponding to the antioxidant in the engine oil by a following equation (A), and calculates the oxidation induction time corresponding to the antioxidant as the first antioxidant performance, by integrating the calculated rate of change, and
• wherein said second antioxidant performance-estimating means calculates a rate of change in oxidation induction time corresponding to the peroxide decomposer in the engine oil by a following equation (B), and calculates the oxidation induction time corresponding to the peroxide decomposer as the second antioxidant performance, by integrating the calculated rate of change,
• d[OIT]AH/dt=k1+k2×[NOx]2+k3×[FUEL]2 (A)
• d[OIT]ZN/dt=[OIT]ZN×(k4+k5×[NOx]2+k6×[FUEL]2) (B)
• wherein
• d[OIT]AH/dt:
• rate of change in the oxidation induction time corresponding to the antioxidant,
• d[OIT]ZN/dt:
• rate of change in the oxidation induction time corresponding to the peroxide decomposer,
• [OIT]ZN:
• oxidation induction time corresponding to the peroxide decomposer,
• k1 to k6:
• reaction rate coefficients,
• [NOx]:
• NOx concentration in the crankcase, and
• [FUEL]:
• concentration of fuel in the engine oil.