US 7,031,822 B1 · On-vehicle electronic control unit

Abstract

In an on-vehicle electronic control unit, error in output voltages from a constant voltage power supply circuit (C.V.P.S.) for use in a reference power supply of an A/D converter, occurs due to temperature rise. Whereby, there is a problem of the decrease of an A/D conversion accuracy. A C.V.P.S. supplies a voltage to analog sensors and to an AD converter. Furthermore, an output from a temperature sensor that is disposed in the neighborhood of the C.V.P.S. is stored in a memory as a contrast temperature data T at a time point of shipping. In addition, voltage fluctuation characteristic data due to the change of temperatures of the C.V.P.S. and detection fluctuation characteristic data accompanied by the change of voltages of the analog sensor group have preliminarily been stored, and the fluctuations in digital converted values accompanied with the change of temperatures in the neighborhood of the C.V.P.S. are compensated.

An on-vehicle electronic control unit that comprises a microprocessor including a non-volatile memory storing a control program and a control constant to be transferred and written via an external tool, and an operation processing RAM memory;

said on-vehicle electronic control unit further comprises a constant voltage power supply circuit section, a temperature detection sensor, and a multi-channel AD converter, as well as said non-volatile memory further contains a calibration processing data, a conversion processing data, and a program acting as compensation operation means;
said constant voltage power supply circuit section is fed with an electric power from an on-vehicle battery to generate a predetermined constant voltage output, and feeds an electric power to said microprocessor, non-volatile memory, RAM memory, multi-channel AD converter, and an analog sensor group that is connected to said multi-channel AD converter;
said temperature detection sensor is constructed of a heat-sensitive element that is disposed in the neighborhood of said constant voltage power supply circuit section, and is fed with an electric power from said constant voltage power supply circuit section to generate a temperature detection voltage responsive to a temperature in the neighborhood of the constant voltage power supply circuit section;
said multi-channel AD converter is a conversion circuit element to which an output voltage from said analog sensor group and temperature detection sensor, which generates the maximum digital output of a predetermined resolution when an analog input voltage of an AD converter is equal to a reference voltage that is supplied from said constant voltage power supply circuit section, and which selectively inputs to said microprocessor digital converted values with respect to a large number of analog inputs;
said calibration processing data is data of measurement results obtained by means of a measuring device externally disposed being transferred and written from said external tool in adjustment operation stage of said on-vehicle electronic control unit, and said calibration processing data contains external measured data as to a temperature in the neighborhood of said constant voltage power supply circuit section to be estimated from an environmental temperature at a time point of adjustment operation, and an actual output voltage from said constant voltage power supply circuit section at a time point of adjustment operation, as well as contains as a contrast data a temperature detection voltage of said temperature detection sensor that is digital-converted with said multi-channel AD converter at a time point of adjustment operation;
said conversion processing data contains an average detection fluctuation characteristic data statistically calculated preliminarily by the actual measurement and determination for a large number of sensors as to fluctuation characteristics of a power supply voltage versus a detection output voltage of a part or all of the analog signals to be inputted to said multi-channel AD converter;
said voltage estimation means is means for estimating an output voltage from a constant voltage power supply circuit section under a different temperature environment based on a detection output from said temperature detection sensor and said calibration processing;
and
said compensation operation means is detection value compensation means for compensating at least a part of the values of the digital conversion voltage converted by said multi-channel AD converter based on the output voltage from the constant voltage power supply circuit section estimated by said voltage estimation means, and said conversion processing data.

6 more elements

On-vehicle electronic control unit

Life of this patent

On-vehicle electronic control unit

Life of this patent

Abstract

Claims12