JP2018185245A - Vehicle-mounted electronic control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle-mounted electronic control device which solves the problem that error of a sensor detection signal of a sensor configured to generate detection signal voltage with respect to a potential difference between a ground terminal and a power supply terminal of the sensor cannot be sufficiently corrected, unless voltage drop generated by resistance of things like a harness connecting to a power supply and the ground of the sensor is brought into consideration because the power supply current supplied to the sensor varies depending of a state of the sensor.SOLUTION: Pre-storing values of necessary wiring resistance and harness resistance and the like in a storage unit, and correcting an A/D converted value of a sensor detection signal together with a monitoring result of voltage at a branching point as needed allows for reducing the error of the detection signal of a sensor configured to generate detection signal voltage with respect to a potential difference between a ground terminal and a power supply terminal of the sensor.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an on-vehicle electronic control device that controls the operation of a vehicle based on a detection result detected by a sensor.

  2. Description of the Related Art Conventionally, a vehicle is equipped with an in-vehicle electronic control device configured with a microcomputer or the like that functions as a control center that electrically controls the operation of a vehicle engine or the like. In this control apparatus, sensor detection signals detected by various sensors that collect various information necessary for control are input, and various controls are performed based on the input sensor detection signals.

  A variety of sensors are mounted on the vehicle, and as a sensor that outputs the vehicle state as a detection signal voltage with respect to a potential difference between the ground terminal and the power terminal of the sensor, a throttle position sensor that indicates an accelerator opening is known. ing.

  For example, in the following document (see Patent Document 1), as shown in FIG. 2, a first monitor circuit that divides and monitors a power supply voltage VCC that is a reference voltage of the A / D converter 4 and a power supply to the sensor 2. Is provided with a second monitor circuit that divides and monitors the voltage AVCC of the power supply terminal 8 that supplies the signal, and corrects the detection signal of the sensor 2 based on the A / D conversion values of V1 and V2 that are the outputs of the respective monitor circuits. ing. Here, the voltage AVCC is a voltage tracker output that follows the power supply voltage VCC with a certain accuracy.

  Further, by using a power supply circuit with a feedback control function that is controlled so that the voltage AVCC of the power supply terminal 8 is kept constant by returning the voltage AVCC of the power supply terminal 8 that supplies power to the sensor 2 to the power supply circuit 6. A configuration that suppresses fluctuations in the power supply voltage AVCC of 2 is generally known.

JP 2007-69741

  Since the current of the power supplied to the sensor 2 varies depending on the state of the sensor 2, the sensor detection signal error due to the voltage variation of the power supply terminal 8 in the configuration of Patent Document 1 and the conventional configuration using the power supply circuit with a feedback function. However, the voltage drop caused by the resistance of the harness connected to the power supply and the ground of the sensor 2 cannot be taken into account, and the detection signal voltage for the potential difference between the ground terminal and the power supply terminal of the sensor 2 is output. The error of the sensor detection signal cannot be corrected sufficiently.

  Accordingly, the present invention has been made in view of the above, and an object of the present invention is to reduce an error in a detection signal of a sensor that outputs a detection signal voltage with respect to a potential difference between a ground terminal and a power supply terminal of the sensor. Another object of the present invention is to provide an in-vehicle electronic control device that improves the controllability of the vehicle based on the detection result of the sensor.

  In order to achieve the above object, a first aspect of the present invention provides a sensor that outputs a vehicle state as a detection signal voltage with respect to a potential difference between a ground terminal and a power supply terminal of the sensor, and a power supply circuit that generates and outputs a power supply voltage. An A / D converter for A / D converting the sensor detection signal of the sensor using the power supply voltage output from the power supply circuit as a reference voltage, and A of the sensor detection signal obtained by the A / D converter In a vehicle-mounted electronic control device having a control means for controlling the operation of the vehicle based on a D / D conversion value, provided in the middle of a substrate wiring from the power supply circuit to a power supply terminal for supplying power to the sensor An A / D converter for A / D converting the voltage at the branch point, a resistance value from the power supply circuit to the branch point, a resistance value from the branch point to the power supply terminal, and the sensor from the power supply terminal For up to A storage device for storing a resistance value such as a tone and a resistance value of a harness or the like from the sensor to a ground terminal of the on-vehicle electronic control device, and the control means is the A / D converter Using the A / D conversion value of the voltage at the branch point and the four resistance values stored in the storage device, the A / D conversion value of the sensor detection signal obtained by the A / D converter is corrected. It is characterized by doing.

  According to the first aspect of the present invention, the four resistance values required in advance are stored in the storage device, and the A / D conversion value of the sensor detection signal is appropriately displayed together with the monitoring result of the voltage at the branch point. It is possible to reduce the error of the detection signal of the sensor that outputs the detection signal voltage with respect to the potential difference between the ground terminal and the power supply terminal of the sensor. Thereby, the controllability of the vehicle based on the detection result of the sensor can be improved.

  According to a second aspect of the present invention, in the on-vehicle electronic control device according to the first aspect, of the four resistance values stored in the storage device, the resistance value from the power supply circuit to the branch point, and the branch point The resistance values from to the power supply terminal are stored as absolute values of the respective resistance values.

  According to the second aspect of the present invention, absolute values such as a resistance value measured in advance and a theoretical resistance value obtained from design information such as the width, length and thickness of the substrate wiring are stored. By doing so, various voltage values and the like described later can be directly obtained.

  According to a third aspect of the present invention, in the on-vehicle electronic control device according to the first aspect, of the four resistance values stored in the storage device, the resistance value from the power supply circuit to the branch point, and the branch point One of the resistance values from the power supply terminal to the power supply terminal is stored as an absolute value, and the other is stored as a ratio to the one resistance value.

  According to the third aspect of the present invention, only one resistance value can be measured as an absolute value, and the other can be stored as a design-determined ratio, thereby simplifying the manufacturing process. Is possible. Also, when storing a theoretical resistance value instead of a measured value, the calculation formula can be simplified by storing the other as a ratio. For example, when the ratio is 1: 1, the absolute values of both are equal, and the parameter used for the calculation can be reduced by one.

  According to a fourth aspect of the present invention, in the in-vehicle electronic control device according to the first aspect, of the four resistance values stored in the storage device, the resistance value of a harness or the like from the power supply terminal to the sensor, The resistance value of a harness or the like from the sensor to the ground terminal of the on-vehicle electronic control device stores each resistance value as an absolute value.

According to invention of Claim 4 of the said characteristic, absolute values, such as the theoretical resistance value calculated | required from resistance values, such as the harness measured previously and the thickness and length of the conducting wire of a harness By storing, various voltage values described later can be directly obtained.
According to a fifth aspect of the present invention, in the in-vehicle electronic control device according to the first aspect, of the four resistance values stored in the storage device, a resistance value of a harness or the like from the power supply terminal to the sensor, and the The resistance value of the harness or the like from the sensor to the ground terminal of the in-vehicle electronic control device stores either one of the resistance values as an absolute value, and stores the other as a ratio to the one resistance value. .

  According to the fifth aspect of the present invention, only one resistance value can be measured as an absolute value, and the other can be stored as a design-determined ratio, thereby simplifying the manufacturing process. Is possible. Also, when storing a theoretical resistance value instead of a measured value, the calculation formula can be simplified by storing the other as a ratio. For example, when the ratio is 1: 1, the absolute values of both are equal, and the parameter used for the calculation can be reduced by one.

  According to a sixth aspect of the present invention, in the on-vehicle electronic control device according to the first to fifth aspects of the present invention, an A / D conversion is performed on the voltage at the branch point for the four resistance values stored in the storage device. The input resistance value of the / D converter is sufficiently large.

  According to the sixth aspect of the present invention, since the current flowing from the branch point to the A / D converter is small and the voltage drop can be sufficiently reduced, the detection signal of the sensor can be corrected with high accuracy. .

  According to a seventh aspect of the present invention, in the on-vehicle electronic control device according to the first to fifth aspects, the sensor detection signal of the sensor is A / D converted for the four resistance values stored in the storage device. The input resistance value of the A / D converter is sufficiently large.

  According to the seventh aspect of the present invention, since the current flowing from the sensor to the A / D converter is small and the voltage drop can be sufficiently reduced, the detection signal of the sensor can be corrected with high accuracy.

  According to an eighth aspect of the present invention, in the on-vehicle electronic control device according to any one of the first to fifth aspects, the four resistance values stored in the storage device are applied to the MPU from the ground terminal of the on-vehicle electronic control device. The resistance value to the ground terminal is sufficiently small.

  According to the eighth aspect of the present invention, since the voltage drop due to the current flowing from the ground terminal to the MPU can be sufficiently reduced, the detection signal of the sensor can be corrected with high accuracy.

It is a figure which shows the structure of the vehicle-mounted electronic control apparatus which concerns on Example 1 of this invention. It is a figure which shows the structure of the conventional vehicle-mounted electronic control apparatus.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS The best embodiment for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration of an in-vehicle electronic control device according to a first embodiment of the present invention. 1 is characterized in that the wiring resistance Rcom from the power supply circuit 6 to the branch point S3 and the power supply terminal from the branch point S3 to the configuration shown in FIG. A storage device for storing wiring resistance Ra up to 8, resistance Rh of harness etc. from power supply terminal 8 to sensor 2, and resistance Rg of harness etc. from sensor 2 to ground terminal 9 of in-vehicle electronic control device 1 10 is provided.

  The voltage dividing resistors R3 and R4 of the monitor circuit of FIG. 2 are provided so that the A / D converter 4 of the MPU 3 can monitor a voltage higher than the power supply voltage VCC. Is also applicable, but is omitted for simplicity of explanation.

  The resistance of the harness etc. from the power supply terminal 8 to the sensor 2 is Rh, the resistance of the harness etc. from the sensor 2 to the ground terminal 9 is Rg, the wiring resistance from the power supply circuit 6 to the branch point S3 is Rcom, and the power supply terminal from the branch point S3 If the wiring resistance value up to 8 is Ra, and based on the voltage Vcom of the branch point S3 read by the MPU3 and the detection signal V1 of the sensor 2 read by the MPU3, the potential difference Vs between the power supply side voltage Vsp of the sensor 2 and the ground side voltage Vsg. And the ratio Ratio of Vout to Vs is obtained by the following equation.

Sensor power supply side voltage Vsp = AVCC− (AVCC−Vcom) × (Rcom + Ra + Rh) / Rcom
Sensor ground side voltage Vsg = (AVCC−Vcom) × Rg / Rcom
Therefore, the potential difference Vs between the power supply side voltage Vsp and the ground side voltage Vsg of the sensor is
Vs = AVCC− (AVCC−Vcom) × (Rcom + Ra + Rh−Rg) / Rcom
Detection signal V1 of the sensor 2 read by the A / D converter 4 of the MPU 3 = Vout + (AVCC−Vcom) × Rg / Rcom
Therefore, the ratio of Vout to Vs is
Ratio = Vout / Vs
= (Rcom x V1-(AVCC-Vcom) x Rg) / (Rcom x Vcom-(AVCC-Vcom) x (Ra + Rh + Rg))
Here, since the output voltage AVCC of the power supply circuit 6 is known and the values of the resistors Rcom, Ra, Rh, Rg are stored in the storage device 10 of the MPU 3, the power supply side voltage Vsp of the sensor 2 and the ground side voltage Vsg The ratio Ratio of Vout to the potential difference Vs can be obtained by calculation from the detection signal V1 of the sensor 2 read by the A / D converter 4 of the MPU 3.

  Here, Ra as a parameter can be eliminated from the above formula by expressing Ra as a ratio of Rcom. Of course, if Rcom is expressed as a ratio of Ra, Rcom as a parameter can be eliminated. Similarly, if Rg is expressed as a ratio of Rh, Rg as a parameter can be eliminated from the above formula, and if Rh is expressed as a ratio of Rg, Rh as a parameter can be eliminated from the above formula.

  In the ratio equation, V1 and Vcom are values detected by the A / D converter 4 of the MPU 3, and the reference voltage VCC of the A / D converter 4 is within a tolerance range from the design value (for example, 5.00 V) (for example, + Even if it fluctuates at (−0.10V), it can be seen that the tolerance variation of VCC is absorbed.

  AVCC in the ratio equation is a voltage tracker output voltage that follows a power supply voltage VCC while maintaining a certain accuracy (for example, +/− 0.01 V), variation in VCC tolerance is absorbed, and resistance Rcom, It is smaller than the voltage drop at Ra, Rh, and Rg (for example, the voltage drops between 0.00 V and 0.20 V due to the fluctuation current supplied to the sensor 2).

  The physical quantity indicating the state of the vehicle detected by the sensor 2 is the ratio of Vout to the potential difference Vs between the power supply side voltage Vsp and the ground side voltage Vsg of the sensor 2, that is, Ratio.

  Therefore, the sensor that varies depending on the state of the sensor 2 by correcting the input signal V1 from the sensor 2 from the voltage Vcom at the branch point S3 and the values of the resistors Rcom, Ra, Rh, and Rg stored in the storage device 10 of the MPU3. The error of the detection signal of the sensor 2 due to the current of 2 and the resistance of the harness or the like can be reduced.

  The input resistance value of the A / D converter 4 may be sufficiently larger than the resistance value stored in the storage device 10. The voltage Vcom at the branch point S3 read by the A / D converter 4 of the MPU 3 has the same potential as that at the branch point S3, and the voltage drop hardly occurs, so that the accuracy is further improved.

  Similarly, the input resistance value of the A / D converter 4 of the MPU 3 that reads the detection signal V <b> 1 of the sensor 2 may be sufficiently larger than the resistance value stored in the storage device 10.

  If the resistance value of the ground of the on-vehicle electronic control device is sufficiently smaller than the resistance value stored in the storage device 10, the ground terminal of the on-vehicle electronic control device 1 and the ground terminal of the MPU 3 have the same potential, and a voltage drop occurs. Because it is difficult, the accuracy is improved.

DESCRIPTION OF SYMBOLS 1 ... Vehicle-mounted electronic control apparatus 2 ... Sensor 3 ... MPU
4 ... A / D converter 5 ... battery terminal 6 ... power supply circuit 7 ... ground terminal 8 ... power supply terminal 9 ... ground terminal 10 ... storage devices R1 to R4 ... resistances Rcom, Ra ... wiring resistances Rh, Rg ... resistances of harness, etc.

Claims (8)

A sensor 2 for outputting the state of the vehicle as a detection signal voltage with respect to a potential difference between the ground terminal and the power supply terminal of the sensor;
A power supply circuit 6 for generating and outputting a power supply voltage;
An A / D converter 4 for A / D converting a sensor detection signal of the sensor using a power supply voltage output from the power supply circuit 6 as a reference voltage;
In the vehicle-mounted electronic control device 1 having control means MPU3 for controlling the operation of the vehicle based on the A / D conversion value of the sensor detection signal obtained by the A / D converter 4,
An A / D converter 4 for A / D converting the voltage at the branch point S3 provided in the middle of the substrate wiring from the power supply circuit 6 to the power supply terminal 8 for supplying power to the sensor 2;
A resistance value from the power supply circuit 6 to the branch point S3; a resistance value from the branch point S3 to the power supply terminal 8; a resistance value of a harness or the like from the power supply terminal 8 to the power supply of the sensor 2; A storage device 10 for storing a resistance value of a harness or the like from the sensor 2 to the ground terminal 9 of the in-vehicle electronic control device 1;
The control means includes an A / D conversion value of the voltage at the branch point S3 obtained by the A / D converter 4, and
An in-vehicle electronic control characterized by correcting an A / D conversion value of the sensor detection signal obtained by the A / D converter 4 using four resistance values stored in the storage device 10 apparatus. Of the four resistance values stored in the storage device 10,
A resistance value from the power supply circuit 6 to the branch point S3;
The resistance value from the branch point S3 to the power supply terminal 8 is
The in-vehicle electronic control device according to claim 1, wherein each resistance value is stored as an absolute value. Of the four resistance values stored in the storage device 10,
A resistance value from the power supply circuit 6 to the branch point S3;
The resistance value from the branch point S3 to the power supply terminal 8 is
2. The on-vehicle electronic control device according to claim 1, wherein one of the resistance values is stored as an absolute value, and the other is stored as a ratio to the one resistance value. Of the four resistance values stored in the storage device 10,
A resistance value of a harness or the like from the power supply terminal 8 to the sensor 2, and
The resistance value of a harness or the like from the sensor 2 to the ground terminal 9 of the in-vehicle electronic control device 1 is
The in-vehicle electronic control device according to claim 1, wherein each resistance value is stored as an absolute value. Of the four resistance values stored in the storage device 10,
The resistance value of the harness or the like from the power supply terminal 8 to the sensor 2 and the resistance value of the harness or the like from the sensor 2 to the ground terminal 9 of the on-vehicle electronic control device 1 are either absolute values. The on-vehicle electronic control device according to claim 1, wherein the other is stored at a ratio to the one resistance value. For the four resistance values stored in the storage device 10,
6. The on-vehicle electronic control device according to claim 1, wherein an input resistance value of the A / D converter 4 for A / D converting the voltage at the branch point S3 is sufficiently large. For the four resistance values stored in the storage device 10,
6. The on-vehicle electronic control according to claim 1, wherein an input resistance value of an A / D converter 4 for A / D converting a sensor detection signal of the sensor 2 is sufficiently large. apparatus. For the four resistance values stored in the storage device 10,
6. The on-vehicle electronic control device according to claim 1, wherein a resistance value from the ground terminal 9 of the on-vehicle electronic control device 1 to the ground terminal 7 of the MPU 3 is sufficiently small.

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