JPH0439914B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a bimetal meter that is powered by a bimetallic voltage regulator and is powered by a bimetallic voltage regulator to display measured quantities such as the remaining amount of fuel in an analog manner. It relates to a drive device.

(Prior art) Conventionally, as a drive device for a bimetal meter, for example, taking a fuel level gauge as an example, the one shown in Fig. 3 is known (see "Automotive Optical Handbook" published by the Society of Automotive Engineers of Japan, May 1981). (7th edition, 60 pages).

In FIG. 3, 1 is a bimetallic voltage regulator (mechanical type) for stabilizing the battery voltage _VB , and keeps the effective value of the output voltage constant by controlling the on/off of the switch contact. The power supply voltage stabilized by the bimetallic voltage regulator 1 is supplied to the bimetallic meter 2 with the sensor 3 connected in series.
Since the resistance value r of the sensor 3 changes according to the remaining amount of fuel, the bimetal meter 2 is directly driven by electric power with the drive current determined by the sensor resistance value r to display the remaining fuel amount with a needle.

(Problem to be solved by the invention) However, in such conventional bimetal meter drive devices, the meter drive current also flows through the sensor itself, so a sensor with a large rated capacity must be used. In addition, the diameter of the sensor resistor winding increases, which increases the size of the sensor itself.Furthermore, the thicker wire diameter causes the winding pitch to become rougher, resulting in lower resolution and lower detection accuracy. Although it was simple in terms of performance, it was insufficient in terms of performance.

On the other hand, in recent years, microcomputers have been installed to control various types of vehicles, such as engines and automatic transmissions. Control processing using a microcomputer is possible, and it is desirable to use a microcomputer for fuel display etc. using a bimetal meter.In addition, when using a microcomputer to drive and control a bimetal meter, reliability,
There are cases where it is desirable to use a conventional bimetallic voltage regulator from the viewpoint of cost or installation space, and as is well known, bimetallic voltage regulators have a lower output fluctuation when the battery voltage V _B fluctuates than electronic voltage regulators. is large, and there is a possibility that display errors may occur due to power supply fluctuations. Therefore, if fluctuations in the battery voltage _VB are detected, it is easy to drive a bimetal meter that corrects power fluctuations under program control using a microcomputer, so normally the battery voltage is converted to a digital signal using an A/D converter. It is conceivable to input the data into a microcomputer using

However, if an A/D converter was used to convert the battery detection voltage into a digital signal, the A/D converter would complicate the circuit and increase costs. Changing to a voltage regulator is cheaper and more practical.

(Means for Solving the Problems) The present invention was made in view of these conventional problems, and utilizes the characteristics of a bimetallic voltage regulator that produces a stabilized output by controlling the on/off of switch contacts. The object of the present invention is to provide a bimetal meter drive device that detects battery voltage without using an A/D converter and corrects display errors due to power fluctuations of the bimetal meter, and is configured as follows. It is.

In other words, power is supplied to the bimetal meter using a voltage regulator that stabilizes battery voltage fluctuations by controlling the on/off of switch contacts, and the display data obtained by processing the sensor detection signal with a microcomputer or the like is converted into analog. The bimetal meter is powered by the drive means, and the on/off duty of the bimetal voltage regulator depends on the battery voltage.
By calculating the battery voltage from this on/off duty and correcting display errors due to power supply fluctuations, it is possible to eliminate the need for an A/D converter.

(Embodiment) FIG. 1 is a circuit block diagram showing an embodiment of the present invention, taking as an example the measurement and display of the remaining amount of fuel.

First, to explain the configuration, numeral 10 is a sensor that detects the amount of fuel remaining in the fuel tank. For example, a resistance sensor is used that mechanically detects the vertical movement of a float due to the liquid level and changes the resistance value of a potentiometer. and outputs a sensor detection signal according to the liquid level in the fuel tank. 11 is an A/D converter, which converts the analog detection signal from the sensor 10 into a digital signal.

Reference numeral 12 denotes a control unit using a microcomputer, which inputs sensor detection data from the A/D converter 11, that is, liquid level data, to the measurement calculation means 13, and converts the bottom area of the fuel tank into the liquid level data in the measurement calculation means 13. The remaining fuel amount is calculated by executing a measurement calculation that multiplies the two, and the calculated remaining fuel amount is output as display data.

The output data of the measurement calculation means 13 is supplied to the D/A converter 15 via the correction means 14 which will be explained later, and after converting the display data into an analog display signal, it is sent to the power transistor 16 as a driving means supplying. The power transistor 16 is connected to the bimetal meter 2 as an emitter load.
The bimetal meter 2 is supplied with the battery voltage V _B stabilized by the bimetal voltage regulator 1, and therefore,
The bimetal meter 2 is powered by the operation of the power transistor 16 based on the display signal from the D/A converter 15, and the remaining fuel amount obtained based on the detection signal from the sensor 10 is displayed as a needle.

Since the battery voltage V _B normally fluctuates within a range of about 10 to 16 volts, the bimetallic voltage regulator 1 has the function of obtaining a stabilized output by controlling the on/off of the switch contact in response to fluctuations in the battery voltage V _B. , switch contact ON/OFF
Since the output is stabilized by off control, the stabilized output has an effective value of, for example, 8 volts.
The stabilized output of the bimetallic voltage regulator 1, which has an effective value of 8 volts, corresponds to the duty control of the battery voltage V _B by on/off control _of the switch contact.
When the battery voltage VB increases, the on-duty is lowered, and on the other hand, when the battery voltage _VB decreases, the on-duty is increased, so that a stabilized output with an effective value of 8 volts is always obtained. Therefore, the on-duty in on/off control for output stabilization in the bimetallic voltage regulator 1 depends on the value of the fluctuating battery voltage _VB .
The battery voltage V _B at that time can be known from the on-duty of the regulator output, and the control unit 12 detects the transmission time of the on-duty in a predetermined period from the stabilized output of the bimetallic voltage regulator 1, and calculates the on-duty at that time. means for detecting the battery voltage _VB .

That is, the control unit 12 is provided with a duty detection means 17 that directly inputs the stabilized output of the bimetallic voltage regulator 1, and the duty detection means 17 detects the on-duty of the stabilized output obtained as the on/off control output of the switch contact. To detect. The on-duty detected by the duty detection means 17 is given to the power supply voltage detection means 18, and the power supply voltage detection means 18 determines the current value based on the predetermined correlation of the battery voltage V _B with the on-duty of the regulator stabilized output. Detect battery voltage V _B. Battery voltage V _B detected by power supply voltage detection means 18
is given to the correction means 14, and the correction means 14 detects the deviation ±ΔV from the detected battery voltage _VB with respect to the reference battery voltage Vr=12 volts,
The display data of the remaining fuel amount calculated by the measurement calculation means 13 is corrected according to this deviation. For example, when the battery voltage V _B exceeds the reference voltage Vr, the regulated output of the bimetallic voltage regulator 1 is higher than the effective value of 8 volts, for example, the effective value of 8.3
volts, and if the bimetal meter 3 were to be driven by electric power as it was based on the display data of the measurement calculation means 13, the remaining fuel amount displayed on the bimetal meter 3 would be too large. Therefore, the correction means 14 corrects the display data to be reduced in accordance with the deviation +ΔV when the battery voltage V _B increases. Furthermore, when the battery voltage V _B is smaller than the reference voltage Vr, correction is performed to increase the display data based on the deviation -ΔV at that time. Through this correction, even if the stabilized output of the bimetallic voltage regulator 1 fluctuates in response to fluctuations in the battery voltage _VB , it is possible to always display the correct amount of remaining fuel on the bimetallic meter 3.

Next, the operation of the embodiment shown in FIG. 1 will be explained with reference to the flowchart shown in FIG.

When battery voltage is supplied by turning on the ignition switch, etc., first the block 19
Then, the detection data of the sensor 10 converted into a digital signal by the A/D converter 11 is read into the measurement calculation means 13 of the control unit 12. The measurement calculation means 13 calculates the remaining amount of fuel by multiplying the liquid level of the fuel tank given as sensor detection data by the bottom area of the tank in the next block 20, and outputs display data corresponding to this remaining amount of fuel. Further, the measurement calculation means 13 also performs calculation processing to prohibit an increase in the remaining fuel amount when the liquid level detected by the sensor 10 rises due to conditions other than refueling, such as driving vibration or running on a slope. .

When this calculation process for remaining fuel amount is completed,
In block 21, the duty detection means 17 detects the duty ratio of the stabilized output obtained by on/off control of the bimetallic voltage regulator 1, that is, the on-duty, and in the next block 22, the on-duty detected is detected. The battery voltage _VB is detected based on the battery voltage VB. The battery voltage V _B detected by the power supply voltage detection means 18 is given to the correction means 14, and first compared with the battery reference voltage Vr in the determination block 23. If both are equal, the process proceeds to block 24 where no correction is performed and measurement calculation is performed. A block 25 that outputs the display data of the remaining fuel amount obtained by the means 13 as it is, converts it into an analog signal by the D/A converter 15, and displays the measured remaining fuel amount in analog by driving the bimetal meter 3 with electric power by the power transistor 16. Execute output processing.

On the other hand, determination block 22 determines that the battery voltage V _B
is greater than the reference voltage Vr, the process proceeds to block 26, where the battery voltage _VB and the reference voltage Vr are
The display data corresponding to the remaining fuel amount from the measurement calculation means 13 is corrected to be reduced to a lower value according to the deviation +ΔV from Analog display of corrected display data is performed. In other words, battery voltage +V _B
When Vr is fluctuating to a large value, the stabilized output (effective value) of the bimetallic voltage regulator 1 is higher than when the reference voltage Vr = 12V,
Electric drive based on display data that is not corrected will display a relatively high amount of fuel remaining. However, in the present invention, since the display data is corrected to be lower when the battery voltage V _B is high, even if the power supply voltage to the bimetal meter 3 becomes high, the display data calculated by the measurement calculation means 13 will not change. Corresponding accurate fuel remaining amount display can be performed.

Further, if the battery voltage V _B is smaller than the reference voltage Vr in the determination block 23, the process proceeds to block 27, and the display data corresponding to the remaining fuel amount from the measurement calculation means 13 is increased in accordance with the deviation -ΔV. Perform data correction. When making corrections that increase this display data, the battery voltage
As V _B decreases, the stabilized power supply voltage to the bimetal regulator 3 also decreases, and if the power is driven as it is based on the display data from the measurement calculation means 13, a lower remaining fuel amount will be displayed. However, since the display data is corrected to increase, even if the power supply voltage of the bimetal meter 3 decreases, the remaining fuel amount calculated by the measurement calculation means 13 can be accurately displayed by increasing the display data. can do.

Furthermore, since the battery voltage V _B for correcting display data is detected from the pulse duty obtained by on/off control of the switch contact, which is the stabilized output of the bimetallic voltage regulator 1, the battery voltage V _B is digitally detected. There is no need to use an A/D converter for converting into a signal, and the detection of the pulse duty of the stabilized output and the detection of the battery voltage based on this pulse duty are all achieved by program control of the microcomputer that constitutes the control unit 12.
Since there is no need to use an A/D converter, even if the bimetal voltage regulator 1 is used as is, it is easy to accurately measure and display the remaining fuel amount by correcting display errors of the bimetal meter 3 due to fluctuations in battery voltage. can be realized.

Although the above-mentioned embodiment takes as an example the display of the remaining fuel amount using a bimetal meter, the present invention is not limited to this, and the bimetal type voltage regulator is used to generate a stabilized power source to power the bimetal type meter. The present invention can be applied to any appropriate device as long as it is a device that performs supply.

(Effects of the Invention) As described above, according to the present invention, power is supplied to the bimetal meter by the voltage regulator that stabilizes battery voltage fluctuations by controlling the on/off of the switch contacts, and the sensor detection signal is The display data obtained through arithmetic processing using a microcomputer, etc. is converted into analog, and the driving means drives the bimetal meter with electric power. At the same time, the duty pulse, which is the stabilized output of the bimetallic voltage regulator obtained by on/off control of the switch contact, is generated. Detect the duty ratio, for example on-duty,
Since the battery voltage is calculated from this detected on-duty to correct the display drive of the bimetal meter, the battery voltage is converted to digital data using an A/D converter to correct the display data according to power fluctuations using digital processing. At the very least, the actual battery voltage can be detected from the on/off characteristics depending on the battery voltage of the bimetallic voltage regulator, and the A/D
Since no converter is used, the circuit configuration is simpler and the cost is lower. As a result, it is possible to drive a bimetal meter with electric power without causing display errors due to voltage fluctuations even if the conventionally used bimetal voltage regulator is used as is.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram showing an embodiment of the present invention, FIG. 2 is a flowchart showing the control process of FIG. 1, and FIG. 3 is a circuit block diagram showing a conventional example. 1: Bimetal voltage regulator, 2: Bimetal meter, 10: Sensor, 11: A/D converter, 12: Control unit, 13: Measurement calculation means, 14: Correction means, 15: D/A converter, 16: Power transistor , 17: Duty detection means, 18: Power supply voltage detection means.

Claims (1)

[Scope of Claims] 1. A bimetallic voltage regulator that stabilizes and outputs battery voltage fluctuations through on/off control of switch contacts, a bimetallic meter that receives power supply from the stabilized output of the voltage regulator, and a sensor detection signal. measurement calculation means for converting the data into display data through predetermined calculation processing and outputting the data; driving means for driving the bimetal meter with electric power based on the output data of the measurement calculation means; and battery voltage from the on/off duty of the voltage regulator. 1. A driving device for a bimetal meter, comprising: a battery voltage detecting means for detecting the battery voltage; and a correcting means for correcting the output data of the measurement calculation means based on the detected voltage of the battery voltage detecting means.