JPH01285846A - Apparatus for measuring concentration of alcohol - Google Patents

Abstract

PURPOSE:To measure the concn. of alcohol in an alcohol mixed liquid with high accuracy over a wide range without receiving polarizing effect or relaxing effect, by providing a potential difference type alcohol sensor and a resistor type alcohol sensor. CONSTITUTION:The reference voltage value based on the concn. of alcohol corresponding to the max. value of the voltage detected by a potential difference type alcohol sensor 11 is preset. When the detected voltage of a resistor type alcohol sensor 20 is equal to or less than the reference voltage, the concn. of alcohol is set to the predetermined concn. thereof to be operated by an alcohol concn. operator 21 and, as a result, the output voltage of the sensor 11 has a '1' value over the whole concn. region of alcohol. Therefore, the concn. of alcohol can be measured over a wide measuring range with good linearity and high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an alcohol concentration measuring device for measuring the alcohol concentration in a liquid containing alcohol.

(Prior Art) Recently, alcohol-mixed gasoline or so-called "gasohol", which is a mixture of alcohol and gasoline, has been used in various countries. Genuine gasoline and gasohol naturally differ in octane number, so genuine Karin has a different air-fuel ratio (
The important ratio of air to fuel) A/F is 15:l, whereas the air-fuel ratio of gasohol has the characteristics shown in Fig. 6, and if the alcohol concentration is 100%, the air-fuel ratio is 6°1.

Therefore, when using gasohol, it is necessary to detect the alcohol concentration and control the fuel injection amount, ignition timing, etc.

For this reason, as an alcohol sensor for detecting the alcohol concentration in gasoline, a resistance-type alcohol sensor that detects the alcohol concentration from the difference between the resistance value of gasoline and the resistance value of alcohol has been considered.

This type of resistive alcohol sensor is shown in Figures 7 to 881.
Shown in Figure 0.

In the figure, 1 is a fuel pipe, 2 is an alcohol sensor, and the alcohol sensor 2 includes a pair of electrodes 3 and 4, which are made up of a pair of electrode rods, electrode plates, etc., arranged spaced apart in the fuel pipe 1, and the electrode 3. , 4, and the detection circuit 5 includes a DC power source 6 connected to the electrode 3 on one side, and a detection resistor 7 provided between the DC type s6 and the electrode 4 on the other side. (See Figures 7 and 8).

The alcohol sensor 2 detects from both ends of the detection resistor 7 based on the fact that the resistance value decreases as the alcohol concentration C in the gasoline interposed between the pair of electrodes 3 and 4 increases (see FIG. 9). Alcohol concentration C due to voltage E
This is to detect.

(Problem to be Solved by the Invention) By the way, the voltage characteristics of the resistive alcohol sensor 2 are dominated by the resistance of gasoline in a region where the alcohol concentration C is low, for example, 10% or less, so the voltage characteristics are shown in FIG. 10. Thus, in a region where the alcohol concentration C is 01 or less, the output voltage E hardly changes, and there is a problem that the alcohol concentration C cannot be accurately detected in the low concentration region.

On the other hand, it is widely known that in general, electrolyzers exhibit a polarization effect in which ions accumulate on the electrodes and a relaxation effect that provides resistance to the movement of ions. The alcohol concentration C in the alcohol-mixed gasoline can be determined by immersing .4 in the alcohol mixture and applying electricity.
Even in the resistive alcohol sensor 2 that detects alcohol, a phenomenon occurs in which when the alcohol concentration increases, the electrical conductivity of the electrodes 3 and 4 is lost due to the polarization effect and the relaxation effect, resulting in a decrease in the electrical conductivity.

Therefore, when the alcohol concentration C increases, the output voltage E across the detection resistor 7 should increase, but due to the polarization effect and relaxation effect, the output voltage E decreases in the region where the alcohol concentration C is high.

As a result, a phenomenon occurs in which the output voltage E across the detection resistor 7 rapidly decreases on the high alcohol concentration side, as shown in Figure 1O, and the overall voltage characteristic is such that at a certain concentration (EA) or higher, the same alcohol concentration C is reached. However, there is a problem that alcohol concentration C cannot be detected accurately because it has two values (C2, C3).

As mentioned above, the conventional resistance alcohol sensor 2
In this case, the range in which the detection voltage E proportional to the alcohol concentration C can be obtained is only between the alcohol concentrations C1 and 02, so the disadvantage is that the usable range of the measurement results is narrow and the accuracy of the voltage characteristics as a whole is also inferior. There is a drawback.

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and is an alcohol concentration measurement method that enables the alcohol concentration in an alcohol mixed liquid to be measured over a wide range with high accuracy without being affected by polarization effects or relaxation effects. It provides equipment.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention provides a pair of current-carrying electrodes that are arranged facing each other at a distance in an alcohol mixed liquid and to which a constant voltage or current is applied; a potentiometric alcohol sensor, which has a pair of detection electrodes arranged opposite to each other with a predetermined distance between the detection electrodes, and which detects alcohol concentration using the potential difference between the detection electrodes; A resistive alcohol sensor that detects alcohol concentration from a resistance value in a mixed liquid, and whether or not the resistive alcohol sensor has detected a reference voltage value corresponding to the maximum value of the detection voltage to be detected by the potentiometric alcohol sensor. and determining means for determining the alcohol concentration, and when the determining means determines that the detected voltage of the resistive alcohol sensor is smaller than the reference voltage value, the alcohol concentration is determined as a predetermined alcohol concentration regardless of the detected voltage of the potentiometric alcohol sensor. When it is determined that the voltage is below the reference voltage value, the alcohol concentration is calculated using the detected voltage of the potentiometric alcohol sensor.

For Cf'r) 'Maximum detection voltage detected by the potentiometric alcohol sensor (/i) Set the X quasi-voltage value based on the alcohol concentration corresponding to the reference in advance.The detection voltage of the resistive alcohol sensor is the reference When the alcohol concentration is below the voltage value, by calculating the alcohol concentration as a predetermined alcohol concentration, the output voltage of the potentiometric alcohol sensor will have an I value over the entire alcohol concentration range, resulting in good linearity and high accuracy. It is possible to measure alcohol concentration over a wide measurement range.

〔Example〕

EMBODIMENT OF THE INVENTION Hereinafter, as an example of the present invention, a case where an alcohol concentration measuring device is applied to a fuel injection control device will be described in detail with reference to FIGS. 1 to 5.

Note that the same components as those of the prior art described above will be given the same reference numerals, and their explanation will be omitted.

In the figure, 11 is a potentiometric alcohol sensor; 12.
13 constitutes the alcohol sensor 11, and the fuel pipe 1
It is a current-carrying electrode consisting of a pair of electrode plates spaced apart from each other. It is connected to the DC type @ (14) and a constant voltage or constant current is applied.

16.17 is a detection electrode consisting of another pair of small electrode plates provided between the pair of electrodes 12 and 13, in order to measure the potential difference of the gasoline interposed between them. The electrodes 16.17 are spaced apart from the energizing electrodes 12.13 by a predetermined distance, and are arranged facing each other with a predetermined distance from each other. 18 is the pair of detection electrodes 16 and 17.
In order to detect the potential difference between the detection electrodes 16° and 17
A voltage detection device is connected between the two. Here, as will be described in detail later, the output voltage V of the potentiometric alcohol sensor 11 rises in a low concentration region of the alcohol concentration C, reaches the maximum value Vl11aX, and then becomes inversely proportional to the alcohol concentration C. It has a voltage characteristic that becomes smaller. The voltage detection device 18 is connected to an amplifier 19 that converts the detected voltage V having the above-mentioned characteristics into a transmittable output voltage (
(See Figure 3).

On the other hand, 20 is a resistive alcohol sensor that detects the alcohol concentration C in gasoline in the fuel pipe 1 together with the potentiometric alcohol sensor 11, and the resistive alcohol sensor 20 has a fixed resistor 15 similar to the prior art. A detection voltage E is derived from both ends, and this detection voltage E is output to an alcohol concentration calculation device 21, which will be described later.

Next, reference numeral 21 denotes an alcohol concentration calculation device consisting of a CPU, etc. The input side of the alcohol concentration calculation device 21 is connected to the amplifier 19 and the resistive alcohol sensor 20, respectively, and the output side is connected to an injection amount calculation device 23, which will be described later. It is connected. Reference numeral 22 denotes a storage device such as a ROM or RAM connected to the alcohol concentration calculating device 21. In addition to the block diagram shown in FIG. ■１
A data map of output voltage V versus alcohol concentration C shown as a characteristic diagram in FIG. 4 is also stored. The alcohol concentration calculation device 21 performs concentration calculation processing, which will be described later, based on the data stored in the storage device N22, and then outputs an alcohol concentration signal C to the injection amount calculation device 23.

Here, regarding the reference voltage value v1, the output voltage V of the potentiometric alcohol sensor 11 takes the maximum value Vmax in the low concentration region of the alcohol concentration C. Therefore, using the alcohol concentration C4 corresponding to the maximum value V + w a 11 as a reference, the voltage value when the resistive alcohol sensor 20 detects the alcohol concentration C4 is set to the output voltage V of the potentiometric alcohol sensor 11 or the maximum value. V m a X
, and the voltage value is set as the reference voltage value vl.Next, 23 is a fuel injection amount calculation device, and the injection amount calculation device 23 calculates the alcohol concentration signal C, the crankshaft Angle sensor 24
The amount of fuel to be injected is calculated from the engine rotational speed N, the intake air amount Q from the air flow meter 25, etc., and a fuel injection signal C is output to the injection valve 26. Further, 27 in the figure is an alcohol concentration meter.

The present embodiment is constructed as described above. Next, the functions of the potentiometric and resistance alcohol sensors 11 and 20 will be described first, and then the alcohol concentration calculation process will be described.

A pair of energizing electrodes 12 of the potentiometric alcohol sensor 11
．． 13 and a pair of detection electrodes 1 provided between them.
6.17 is immersed in alcohol-mixed gasoline in the fuel pipe 1. In this state, a pair of current-carrying electrodes 12
．． A constant voltage or current is applied from a DC power supply 14 during the period 13. At this time, if the alcohol concentration C in the alcohol mixed gasoline interposed between the current-carrying electrodes 12 and 13 is high,
Since the resistance value is small, the potential difference between the electrodes 12 and 13 becomes small. Conversely, if the alcohol concentration C is low, the resistance value is large and the potential difference between the electrodes 12 and 13 becomes large.

Therefore, the voltage detection device 18 detects the potential difference between the current-carrying electrodes 12.13 by a pair of detection electrodes 16.17 interposed between the current-carrying molds 8i12.13. In this way, as shown in FIG. 4, it is possible to obtain a voltage characteristic in which the maximum value V may occurs in the low concentration region of alcohol concentration C, and as the alcohol concentration C increases, the output voltage V decreases linearly. The alcohol concentration C in gasoline can be measured using the characteristics. Therefore, the linearity of the output voltage V is better than that of the resistive alcohol sensor according to the prior art, the range of use of the measurement results is wider, and moreover, the concentration can be measured with high accuracy. Further, when detecting the alcohol concentration C, since no current is applied to the detection electrodes 16.17, the electrodes 16.17 are not affected by polarization effects or relaxation effects. Therefore, even if the current-carrying electrodes 12.13 exhibit polarization effects or relaxation effects, the detection electrodes 16.17 can accurately detect the potential difference between the current-carrying electrodes 12.13.

By the way, as mentioned above, the output voltage V from the potentiometric alcohol sensor 11 rises once in the low concentration region and then reaches the maximum value V.
Since m a x is taken, the alcohol concentration C has two values over the entire range, and there is a problem that the alcohol concentration C cannot be detected accurately. On the other hand, the output voltage E of the resistive alcohol sensor according to the conventional technology has two values (C2, C:l) in the high concentration region of alcohol concentration C, but the output voltage E has two values (C2, C: l) in the region of alcohol concentration lower than C2. In contrast, the voltage characteristic has only one value.

Therefore, in this embodiment, by utilizing the characteristics of the output voltage E of the resistive alcohol sensor described above, the output voltage of the potentiometric alcohol sensor 11 is set to the l value over the entire range of the alcohol concentration C. A resistive alcohol sensor 20 is used in combination with the alcohol sensor 11, and the alcohol concentration is calculated from the detected voltages V and E of both alcohol sensors 11 and 20, as described below.

Therefore, this calculation process will be described with reference to the block diagram shown in FIG. First, when the engine is started and processing is started, the alcohol concentration calculation device 21 detects the potentiometric alcohol sensor 11 and the resistance alcohol sensor 2.
The alcohol concentration detection signals are read from 0 as detection voltage values V and E, respectively (steps 1 and 2). on the other hand,
In the next step 3, the alcohol concentration calculation device 21 reads out the reference voltage value V from the storage device 22.

Next, the alcohol concentration calculating device 21 compares the detected voltage value E of the resistive alcohol sensor 20 with the reference voltage value V, and determines the magnitude thereof (step 4). When it is determined in step 4 that E≧V, the process moves to the next step 5, where the detected voltage V-alcohol concentration C map shown in FIG. 4 stored in the storage device 22 is accessed, and the corresponding The alcohol concentration C is determined, and the alcohol concentration signal C is output to the injection amount calculation device 23.

On the other hand, when it is determined in step 4 that E<V, the detected 'tonne pressure V' of the potentiometric alcohol sensor 11 is the maximum value V□, and so on. V to hole 1, and outputs it to the C injection amount calculating device 23 as, for example, an alcohol B degree signal C=C.

2 in the entire range of output voltage V or alcohol concentration C
Since the output voltage V of the potentiometric alcohol sensor 11 always has only one value, the output 'tIT':
The linearity of V is good, and therefore the high-precision C detection results can be used in a wide range of applications.The potentiometric alcohol sensor IJll can be used for calculation of fuel injection and engine control.

In the embodiment, the output voltage V of the potentiometric alcohol sensor 11 reaches its maximum value V at a position where the alcohol concentration is c or about lo%.
Of course, it is assumed that I'll +l

In addition, step 4 is a specific example of a means for determining unissued QQ, and steps 5 and 6 are specific examples of the calculation stage of the present invention, or the present invention is not limited to processing of these steps. It may also be configured by a circuit. Furthermore, although alcohol-mixed gasoline is exemplified as the alcohol-mixed liquid in the embodiments, the present invention can be applied to other alcohol-mixed liquids.

〔Effect of the invention〕

Unreleased 1!11 is as described in detail below, and when the detected voltage value of the resistive alcohol sensor becomes less than the predetermined reference voltage value, the predetermined voltage is applied regardless of the detected voltage by the potentiometric alcohol sensor. By outputting the alcohol concentration, the potentiometric alcohol sensor is configured to take the l value over the entire alcohol concentration range, so the output voltage has good linearity, and the detection results are highly accurate and can be used over a wide range of alcohol concentration measurement devices. You can do it.

[Brief explanation of the drawing]

Figures 1 to 5 relate to embodiments of the present invention, where Figure 1 is a circuit diagram of a potentiometric alcohol sensor, Figure 2 is an explanatory diagram of the configuration of a potentiometric alcohol concentration sensor, and Figure 3 is an alcohol concentration diagram. A system configuration diagram when the measuring device is applied to a fuel injection control device, Fig. 4 is a characteristic line diagram showing the relationship between alcohol concentration and output voltage, Fig. 5 is a flow chart showing concentration calculation processing, and Figs. Figure 1O relates to the prior art: jS6
The figure is a diagram showing the relationship between air-fuel ratio and alcohol concentration.
Figure 7 is an explanatory diagram of the configuration of a resistive alcohol sensor, Figure 8 is a circuit diagram of a resistive alcohol sensor, Figure 9 is a diagram showing the relationship between alcohol concentration and detection resistance, and Figure 10 is an alcohol concentration and output voltage. FIG. DESCRIPTION OF SYMBOLS 11... Potential difference type alcohol sensor, 20... Resistance type alcohol sensor, 21... Alcohol concentration calculation device, 22... Storage device, 23... Injection concentration calculation device. Patent Applicant [Ihon Electronics Co., Ltd. Agent Patent Attorney Kazu Hirose Production Volume Naoki Nakamura Figure 4 1 ・No Alcohol Concentration C (V'10) Figure 5

Claims (1)

[Claims] a pair of current-carrying electrodes that are spaced apart and facing each other in an alcohol mixed liquid and to which a constant voltage or current is applied; A potentiometric alcohol sensor has a pair of detection electrodes and detects alcohol concentration using a potential difference between the detection electrodes, and a resistance type alcohol sensor detects alcohol concentration from a resistance value in the alcohol mixed liquid. an alcohol sensor; and a determining means for determining whether or not the resistive alcohol sensor has detected a reference voltage value corresponding to the maximum value of the detection voltage to be detected by the potentiometric alcohol sensor, and the determining means determines whether the When it is determined that the detection voltage of the resistive alcohol sensor is smaller than the reference voltage value, a predetermined alcohol concentration is calculated regardless of the detection voltage of the potentiometric alcohol sensor, and when it is determined that the voltage is equal to or higher than the reference voltage value, the potential difference is calculated. An alcohol concentration measuring device configured to calculate alcohol concentration using a detection voltage of a formula alcohol sensor.