| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a cetane number discriminating device of fuel in a diesel engine capable of discriminating easily and accurately a cetane number of fuel injected into a combustion chamber. <P>SOLUTION: A minute amount of fuel is injected into a combustion chamber during fuel cut (step S12), a cylinder internal pressure P is acquired via a cylinder internal pressure sensor 40 (step S13). At the same time, a volume V of combustion chamber 12 is acquired based on a crank angle θ via a crank angle sensor 37, a specific heat ratio κ is acquired, and then PV<SP POS="POST">κ</SP>(step S14) is calculated using the cylinder internal pressure P and the combustion chamber volume V and the specific heat ratio κ. Using the calculated three PV<SP POS="POST">κ</SP>(θ<SB POS="POST">start</SB>), PV<SP POS="POST">κ</SP>(θ<SB POS="POST">CN</SB>), PV<SP POS="POST">κ</SP>(θ<SB POS="POST">END</SB>), a combustion percentage MFB (θ<SB POS="POST">CN</SB>) in cylinder to a crank angle θ<SB POS="POST">CN</SB>of a combustion intermediate point at which the cetane value is discriminated. Determine a cetane number index corresponding to the MFB (θ<SB POS="POST">CN</SB>) acquired from a map (step S17). <P>COPYRIGHT: (C)2012,JPO&INPIT |
