JPH0541944B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a resistance-type alcohol concentration detection device for detecting the alcohol concentration in a liquid containing alcohol.

[Conventional technology]

Recently, alcohol-mixed gasoline (hereinafter referred to as "gasohol"), which is a mixture of alcohol and gasoline, has been used in various countries. Naturally, gasohol and genuine gasoline have different octane numbers, so while the air-fuel ratio (weight ratio of air and fuel) A/F of pure gasoline is 15:1, the air-fuel ratio of gasohol is as shown in Figure 13. When 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, in the prior art, as an alcohol sensor for detecting the alcohol concentration in gasohol, a resistance-type alcohol sensor that detects the alcohol concentration from the difference in resistance value between gasoline and alcohol has been considered.

This type of resistive alcohol sensor is shown in FIGS. 14 to 17. In the figure, 1 is a fuel pipe, 2 is an alcohol sensor, and the alcohol sensor 2 has a pair of electrode rods or electrode plates (hereinafter referred to as electrode rods) 3, which are inserted into the fuel pipe 1 at a distance.
4, and a detection circuit 5 connected to the electrode rods 3, 4, the detection circuit 5 includes a DC power source 6 connected to the electric rod 3 on one side, and a DC power source 6 connected to the electrode rod 4 on the other side. and a detection resistor 7 connected in series between the two and detecting the voltage E (see FIG. 15).

The above-mentioned alcohol sensor 2 has a detection resistance based on the fact that the wire resistance value (Ω cm) decreases as the alcohol concentration in the gasohol interposed between the pair of electrode rods 3 and 4 increases (see Fig. 16). 7
The alcohol concentration is detected from the change in the voltage E detected.

[Problem to be solved by the invention]

By the way, when detecting alcohol concentration using the resistive alcohol sensor 2, various factors such as the type of gasohol, water content, fuel temperature, and metal ions deposited from the fuel tank and fuel system parts due to changes over time are detected. The electrical conductivity of the gasohol changes depending on the following factors. Therefore, as shown in Figure 17, even though the alcohol concentration is actually constant, the detected voltage value differs between the initial detection and the detection after the change over time, and the apparent voltage value after the change over time is different. There is a problem in that the alcohol concentration becomes low and it is not possible to determine an appropriate amount of fuel to be supplied.

The present invention was made in view of the above-mentioned problems, and is a resistance-type alcohol concentration detection device that can output a concentration signal corresponding to the alcohol concentration even when gasohol changes due to aging or other factors. The purpose is to provide equipment.

[Means to solve the problem]

The configuration adopted by the present invention in order to solve the above-mentioned problems detects the alcohol concentration in a liquid containing alcohol based on the resistance value between electrodes,
A first resistance-type alcohol concentration detection means for converting into an electrical signal and the first alcohol concentration detection means are configured with different specifications, and detect the alcohol concentration in the liquid based on the resistance value between the electrodes. , a second resistance type alcohol concentration detection means for converting into an electrical signal, an output difference calculation means for calculating the output difference of the electrical signal from each of the resistance type alcohol concentration detection means, and an output difference calculation means output from the output difference calculation means. and a concentration calculation means for calculating alcohol concentration based on the output difference of the electrical signal with respect to the alcohol concentration.

[Effect]

An electrical signal corresponding to the alcohol concentration in the alcohol mixed liquid is detected at an initial time and after changes over time using first and second resistive alcohol concentration detection means having different endpoints. Regarding the electrical signals from each of these resistance-type alcohol concentration detection means, the output difference from the output difference calculation means at the initial time is substantially equal to the output difference from the output difference calculation means after changes over time. Therefore, the output difference between the electrical signals and the alcohol concentration at the initial time are stored as initial values. Then, the output difference between the electrical signals after the change over time is calculated by the output calculation means, and this output difference is output to the concentration calculation means. It is possible to output an alcohol concentration signal corresponding to

〔Example〕

Embodiments of the present invention will be described in detail below with reference to FIGS. 1 to 12. Note that the same reference numerals are given to the same components as those of the prior art described above, and the explanation thereof will be omitted.

1 to 8 show a first embodiment of the present invention. In the figure, reference numeral 11 indicates a first resistance alcohol sensor (hereinafter referred to as the first
The first alcohol sensor 11 consists of a pair of electrode rods 12 and 13 inserted spaced apart into the fuel pipe 1, and a detection circuit 14. A DC power source 15 connected to the electrode rod 12 and a detection resistor 1 connected in series between the electrode rod 13 on the other side and the DC power source 15.
It consists of 6.

On the other hand, 17 is a second resistance alcohol sensor (hereinafter referred to as a second alcohol sensor) provided in the fuel pipe 1 together with the first resistance alcohol sensor 11.
7 is a pair of electrode rods 1 inserted into the fuel pipe 1
8, 19, and a detection circuit 20 having the same circuit configuration as the first alcohol sensor 11, and the detection circuit 20 is different from the first alcohol sensor in that it is composed of a DC power supply 21 and a detection resistor 22. There is no difference from 11. However, the second alcohol sensor 17 has specifications such as the distance l between the electrodes 18 and 19, the electrode area S, the applied voltage E of the DC power supply 21, and the resistance value _R1 of the detection resistor 22, etc. The detection voltage value of the first alcohol sensor 11 is different from that of the first alcohol sensor 11 when the alcohol concentration of the same gasohol is detected.
It is designed to output a detected voltage value _E2 different from _E1 .

Then, the above-mentioned pair of alcohol sensors 1
1 and 17, the known alcohol concentration C of gasohol at the initial stage is detected as voltage values E ₁ and E ₂ , respectively, and the alcohol concentration C′ of gasohol after the change over time is detected as voltage values E ₁ ′ and E ₂ ′. It is designed to detect each.

23 is the pair of alcohol sensors 11 and 17;
The output difference calculation circuit 22 is connected to each alcohol sensor 11, 1 as described above.
The output voltage difference ΔE _A between the initial detection voltage value E ₁ and E ₂ output by 7 and the detection voltage value E ₁ ′ after change over time.
The output voltage difference ΔE _A ′ of E ₂ ′ is calculated. This processing operation is performed as shown in FIG.

Next, 24 is an initial value storage circuit connected to the output side of the output difference calculation circuit 23, and the initial value storage circuit 24 stores the alcohol concentration C when the known alcohol concentration C at the initial time is changed. The voltage difference ΔE _A outputted from the output difference calculation circuit 23 for the output difference calculation circuit 23 is stored as a map of initial values.

On the other hand, 25 indicates a concentration calculation circuit connected to the output side of the output difference calculation circuit 23 and also connected to the initial value storage circuit 24.
is the initial value storage circuit 2 based on the output voltage difference ΔE _A ' after the change over time output from the output difference calculation circuit 23.
Arithmetic processing is performed with reference to the initial values (C, ΔE _A ) stored in 4, and a concentration signal corresponding to the alcohol concentration is output. This processing operation is shown in FIG.

Here, the initial alcohol concentration C and the output voltage difference ΔE _A have characteristics as shown by the solid line in FIG. On the other hand, if we look at the characteristics of the alcohol concentration C' and the output voltage difference ΔE _A ' after the change over time, we can see that the two characteristics are substantially the same before and after the change over time, as shown by the broken line in Figure 6. I understood. As a result, by referring to the initial alcohol concentration C and the output voltage difference ΔE _A , and finding the output voltage difference ΔE _A ′ after the change over time,
It is possible to know the alcohol concentration C' after changes over time.

According to this embodiment, a pair of alcohol sensors 11 and 17 with different specifications are used to detect gasohol at the initial stage as voltage values E ₁ and E ₂ for a known alcohol concentration C, and the detected voltage is The relationship between the output voltage difference ΔE _A between the values E ₁ and E ₂ and the known alcohol concentration C is stored as an initial value.

On the other hand, for example, the output voltage difference ΔE _A ′ of gasohol after aging is calculated in the same manner, and based on the output voltage difference ΔE _A ′, the initial value C shown in FIG.
Since the alcohol concentration C' is calculated with reference to ΔE _A , the alcohol concentration C' can be calculated for gasohol after aging under the same conditions as at the initial stage. Therefore, even if gasohol changes over time due to various factors such as the precipitation of metal ions, it is possible to output a concentration signal corresponding to the alcohol concentration C' while abstracting from these various factors.

Next, FIGS. 9 to 12 show a second embodiment of the present invention. Note that the same components as those of the first embodiment described above are designated by the same reference numerals.

FIG. 9 shows the first part of the apparatus of this embodiment.
The first alcohol sensor 31 includes a pair of electrode rods 32 and 33.
The detection circuit 34 has a DC power source 35 and a detection resistor 36, and has the same circuit configuration as the alcohol sensors 11 and 17 of the first embodiment.

On the other hand, FIG. 10 shows a second resistive alcohol sensor 37 of this embodiment, and the second alcohol sensor 37 has a detection circuit different from that of the first alcohol sensor 31. That is, the second alcohol sensor 37 consists of a pair of electrode rods 38 and 39 and a detection circuit 40, and the detection circuit 40 includes a DC power source 41 connected to the electrode rod 38 on one side and the electrode rod 39 on the other side. a detection resistor 42 directly connected between the DC power source 41 and the DC power source 41;
A parallel resistor 43 is connected between the electrode rods 38 and 39 in parallel.

A pair of alcohol sensors 31 according to this embodiment,
37 has the above-mentioned configuration, and when detecting the alcohol concentration of the same gasohol, it outputs different detection voltage values E ₃ and E ₄ at the initial stage, and outputs different detection voltage values E ₃ ′ and E ₄ after changing over time. There is no difference from the pair of alcohol sensors 11 and 17 of the first embodiment in that they each output .

Then, the above-mentioned pair of alcohol sensors 3
1 and 37 are output difference calculation circuits 2 as in the first embodiment.
It is connected to the input side of 3.

The present embodiment has the above-described configuration, and a pair of alcohol sensors 31 and 37 measure the alcohol concentrations C and C' of gasohol at the initial time and after changes over time using voltage values E ₃ ,
Detected as E ₄ and E ₃ ′, E ₄ ′, detected voltage values E ₃ , E ₄
The output difference calculation circuit 23 calculates the difference voltages ΔE _B and ΔE _B ' from E ₃ ' and E ₄ '. Then, the initial alcohol concentration C and the output voltage difference ΔE _B are stored in the initial value storage circuit 24 as an initial value map, and the concentration calculation circuit 25 calculates the output voltage difference ΔE _B ′ when changing over time.
Based on this, perform calculation processing by referring to the initial value,
The point of outputting the concentration signal is the same as in the first embodiment.

Note that each embodiment uses a pair of electrode rods 12, 13, 1
Although it has been described that the change in voltage due to the change in resistance between 8, 19, 32, 33 and 38, 39 is detected as the alcohol concentration, the alcohol concentration may also be detected from the change in resistance value. In addition, although gasohol is taken as an example of the alcohol mixed liquid in each embodiment, the present invention is as detailed above, and the alcohol concentration in the alcohol mixed liquid is detected by a pair of resistance alcohol concentration detection methods having different specifications. Since the electrical signal is detected as an electrical signal by the means, this electrical signal is computed by the output difference computing means, and the alcohol concentration is computed based on this output difference by the concentration computing means. The alcohol concentration can be determined by referring to the initial value based on the output difference after changes over time, and the alcohol concentration can be detected without being affected by various factors that change over time. .

[Brief explanation of the drawing]

1 to 8 show a first embodiment of the present invention, in which FIG. 1 is a configuration diagram of an alcohol concentration detection device, FIG. 2 is a circuit diagram of a first resistive alcohol sensor, and FIG. 3 is a circuit diagram of a first resistive alcohol sensor. A circuit diagram of the second resistive alcohol sensor, Fig. 4 is a block diagram showing the overall configuration of this embodiment, Fig. 5 is a characteristic diagram showing the relationship between alcohol concentration and output voltage before and after changes over time, and Fig. 6 is a diagram showing the relationship between the output voltage difference before and after aging of alcohol-mixed gasoline and the alcohol concentration, FIG. 7 is a flowchart showing initial value storage processing, FIG. 8 is a flowchart showing concentration calculation processing, and FIGS. FIG. 12 shows a second embodiment of the present invention, FIG. 9 is a circuit diagram of a first resistive alcohol sensor constituting the alcohol concentration detection device, and FIG. 10 is a circuit diagram of a second resistive alcohol sensor. , Fig. 11 is a characteristic diagram showing the relationship between alcohol concentration and output voltage before and after aging, Fig. 12 is a characteristic diagram showing the relationship between output voltage difference and alcohol concentration before and after aging of alcohol-mixed gasoline, and Fig. 13. 17 to 17 relate to the prior art,
Fig. 13 is a characteristic diagram showing the relationship between air-fuel ratio and alcohol concentration, Fig. 14 is a configuration diagram of an alcohol concentration detection device, Fig. 15 is a circuit diagram of a resistance type alcohol sensor, and Fig. 16 is a graph showing alcohol concentration and resistance type. A characteristic diagram showing the relationship between alcohol sensor resistance and FIG. 17 is a characteristic diagram showing the relationship between alcohol concentration and output voltage before and after aging. 11, 31...first resistance alcohol sensor, 17, 37...second resistance alcohol sensor.

Claims (1)

[Claims] 1. A first resistance-type alcohol concentration detection means that detects the alcohol concentration in a liquid containing alcohol based on the resistance value between electrodes and converts it into an electric signal, and the first alcohol concentration detection means have specifications. a second resistance-type alcohol concentration detection means configured differently and configured to detect the alcohol concentration in the liquid based on the resistance value between the electrodes and convert it into an electrical signal;
Output difference calculating means for calculating the output difference of the electrical signals from each of the resistive alcohol concentration detecting means; and concentration calculating means for calculating the alcohol concentration based on the output difference of the electric signals with respect to the alcohol concentration output from the output difference calculating means. A resistance-type alcohol concentration detection device comprising calculation means.