JPH01224655A - Resistance type alcohol concentration measuring instrument - Google Patents

Abstract

PURPOSE:To measure an exact alcohol concn. by using 1st and 2nd alcohol sensors of different specifications, computing the voltage values before the change with time and computing the alcohol concn. from the voltage value before the previously determined change with time in accordance with the computed voltage value. CONSTITUTION:An arithmetic unit 24 reads the output voltages E1, E2 from the 1st, 2nd alcohol sensors 11, 17 of the different specifications under the control of an arithmetic circuit 26 when the processing is started. The arithmetic unit, thereafter, makes computation in accordance with the read voltages E1, E2 and determines the margin for the change with time, determines the correction voltage ER by the prescribed equation and further determines the estimated output voltage E'1 before the change with time. After the voltage E'1 is computed in such a manner, the circuit 26 accesses the output voltage E10 before the change with time corresponding to the voltage E'1 by referring to a map 28 in a memory circuit 27 and determines the alcohol concn. in the position where E'1=E10 is attained. This concn. is computed as the true alcohol concn. The determined true alcohol concn. C is outputted to a fuel injection rate computing device 29 and an alcohol concn. meter 30 and is again returned.

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.

[Conventional technology]

In general, in Japan, it is prohibited to add alcohol or other foreign liquids to gasoline, which is used as automobile fuel. However, in some foreign countries, alcohol-mixed gasoline, which is alcohol mixed with gasoline, is It is used as "gasohol". Since genuine gasoline and gasohol naturally have different octane numbers, the air-fuel ratio (weight ratio of air and fuel) A/F of genuine gasoline is 15:l, whereas the air-fuel ratio of gasohol has the characteristics shown in Figure 8. Therefore, 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 fuel injection, 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 gasoline resistance value and the alcohol resistance value has been studied.

This type of resistive alcohol sensor is shown in FIGS. 9-12.

In the figure, ■ is a fuel vibrator, and 2 is an alniel sensor. 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 [6 and the electrode 4 on the other side. (See Figures 9 and 10).

The alcohol sensor 2 has a detection resistor based on the fact that as the alcohol concentration C in the gasoline interposed between the pair of electrodes 3.4 increases, the linear resistance value (Ω・c+s) decreases (see FIG. 11). The alcohol concentration C is detected by the output voltage E from both ends of the alcohol.

[Problem to be solved by the invention]

By the way, when detecting the alcohol concentration C using the resistive alcohol sensor 2, the type, property, water content, and fuel temperature of gasoline at the time of detection, as well as metal ions precipitated from the fuel tank and fuel system parts due to changes over time, are detected. The electrical conductivity of alcohol-mixed gasoline changes due to various factors such as: Therefore, even though the alcohol concentration C is constant, the detected voltage E differs between the initial period and after the change over time, as shown in FIG. 12, and the alcohol concentration C apparently becomes lower after the change over time. However, there is a drawback that it becomes impossible to perform appropriate fuel injection amount control.

The present invention was made in view of the above-mentioned drawbacks of the prior art, and an object of the present invention is to provide an alcohol concentration measuring device that can correct the initial alcohol concentration even when the alcohol concentration of an alcohol mixed liquid changes over time. shall be.

[Means to solve the problem]

In order to achieve the above object, the present invention includes a first alcohol concentration detection means that detects the alcohol concentration in a liquid containing alcohol based on a resistance value between electrodes and outputs it as a voltage signal; The alcohol concentration detecting means is configured with different specifications from the alcohol concentration detecting means, which detects the alcohol concentration in the liquid based on the resistance value between the electrodes and outputs it as a voltage signal, and the first alcohol concentration detecting means. Second
Based on the voltage signal from the alcohol concentration detection means of
Voltage value calculation means for calculating a voltage value before time-dependent change based on the first alcohol concentration detection means.

With respect to the liquid, storage means stores the mixed alcohol concentration and the voltage value before time change outputted from the first alcohol concentration detection means, and the voltage value calculated by the voltage value calculation means refer to the storage means,
and an alcohol concentration calculating means for calculating changes in alcohol concentration over time.

[Effect]

Using the first alcohol concentration detection means, the relationship between the alcohol concentration mixed in the liquid and the output voltage is stored in advance in the storage means as a value before time-dependent change (initial time). ．． Using the second alcohol concentration detection means, the alcohol concentration after change over time (at the present moment) is detected. And these first. Based on the detected voltage value from the second alcohol concentration detection means, the voltage value calculation means estimates and calculates the voltage value before the change over time. moreover.

The alcohol concentration calculation means calculates the alcohol concentration at the point where the calculated voltage value is equal to the voltage value stored by the storage means as the alcohol concentration at the first time i.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to FIGS. 1 to 7.

In the same figure, reference numeral 11 denotes an alcohol sensor if installed in the fuel pipe l, and the alcohol sensor 11 includes a pair of electrodes 12.13 and each electrode 12. The detection circuit 14 is composed of a DC power supply 15 connected to the electrode 12 on one side, and a detection resistor 16 provided between the DC power supply 15 and the electrode 13 on the other side. (see FIG. 2), and generates an output voltage E1 from both ends of the detection resistor 16. Note that this configuration is substantially the same as the alcohol sensor 2 according to the prior art.

On the other hand, 17 indicates a second alcohol sensor provided in the fuel vibe 1 together with the first alcohol sensor 11, and the second alcohol sensor 17 also has a pair of electrodes 18 and 19 spaced apart in the fuel pipe 1. , each electrode 18.19
and a detection circuit 20 connected to the detection circuit 20.
A DC power supply 21 connected to the electrode 18 on one side, and a detection resistor 22 provided between the DC power supply 21 and the electrode 19 on the other side.
and a parallel resistor 23 connected in parallel with the electrodes 18 and 19 (see FIG. 3), and generates an output voltage E2 from both ends of the detection resistor 22.

Here, the first alcohol sensor 11 has a pair of electrodes 12
．． 13 and a detection resistor 16 are connected in series with the DC power supply 15, and a change in resistance between the electrodes 12 and 13 is immediately derived as a change in the output voltage E1. On the other hand, in the second alcohol sensor 17, a pair of electrodes 18.
A parallel resistor 23 is connected in parallel with the electrodes 18 .
Even if there is a change in the resistance between 19 and 19, the circuit resistance including the detection resistor 22 does not change significantly, so the output voltage E2 from the detection resistor 22 is not affected by the alcohol concentration C and outputs a substantially constant voltage. It has become. In this way, the first
．． By changing the specifications of the second alcohol sensor 11, 17, the output voltages El and E2 have characteristics as shown in FIG. In Fig. 7, the voltage characteristics El and E2 indicated by dotted lines indicate the output voltage after the change over time (at the present time), and the voltage characteristics EIO and E20 indicated by the solid line indicate the output voltage before the change over time (at the initial time). It shows.

In addition, the :jSA diagram shows a block diagram showing the concentration measuring device according to the present embodiment, and 24 in the figure is a calculation device constituted by, for example, a microcomputer, and the calculation device 24
is an input/output control circuit 25, a processing circuit 26 consisting of a CPU, etc.
．． It is configured to include a memory circuit 27 consisting of RAM, ROM, etc., and a map 28 having characteristics as shown in FIG. 5 is stored in the memory circuit 27, as well as a program etc. shown in FIG. 6. , the alcohol concentration C before the change over time is determined by arithmetic processing to be described later.

The input side of the input/output control circuit 25 is the first . The second alcohol sensors 11 and 17 are connected, and the output side is connected to, for example, a fuel injection amount calculation unit 2129 and an alcohol concentration meter 30.

Here, the map 28 corresponds to the first alcohol sensor 11.
Using the known alcohol concentration C before the change over time,
It stores the relationship between the output voltage EIG and the alcohol concentration C, and is a characteristic plotted by actual measurements for each alcohol concentration.

The present embodiment is configured as described above, but the first. FIG. 6 and FIG. This will be explained with reference to Figure 7.

First, the true alcohol concentration calculation principle according to this embodiment will be explained.

First, in FIG. 7, if we look at the current output voltage E1 (after change over time) of the first alcohol sensor 11 and the output voltage EIO before change over time, we can see that if the corrected voltage due to change over time is ER, then the output voltage for one car There is a relationship between E1 and EIO as follows: E+o=E1-ER-...''(1).

On the other hand, when focusing on the correction voltage ER, as is clear from FIG. 7, the correction voltage ER increases in proportion to the alcohol concentration C. Therefore, the output voltage E1. If EIO is a linear function related to alcohol concentration C, then correction voltage ER is also a linear function proportional to alcohol concentration, that is, ER=aα+b (2) where a, b: constant α: time It is given as a change allowance.

Furthermore, let's look at the change over time α. It is assumed that the output voltage E2 from the second alcohol sensor 17 does not depend on the alcohol concentration before and after the change over time, and is always a constant output voltage. On the other hand, it is assumed that the output voltage El of the first alcohol sensor 11 increases in response to changes over time, regardless of the same alcohol concentration. Then, the rate of change over time in the output voltage E1 with respect to the output voltage E2 is proportional to the ratio of El and E2, that is, El/E2. As a result, the aging variation α is in relation to the output voltage E1.

α=El−βXI, 1/E2 (3) where β: can be given as a constant.

Thus, from Equation (1) or Equation 3), the estimated output voltage El' before the change over time can be obtained as El'=E1 -ER (4) . Note that if there is no change over time, the second term on the right side of equation (4) will be zero, so the constant a is determined by actual measurement of the alcohol concentration.

b and β may be determined as appropriate.

Next, in order to execute the above alcohol concentration calculation principle,
The arithmetic processing by the arithmetic unit 24 will be described with reference to FIG.

First, when processing is started, the arithmetic unit 24
6 under the control of the first. Second alcohol sensor 11,1
The output voltage from E1. Read E2 (step l)
. In the next step 2, the equation (3) is calculated based on the read output voltages El and E2, and the aging variation α is calculated.
In the next step 3, the corrected voltage ER is determined by the equation (2), and in the next step 4, the estimated output voltage El' before the change over time is determined by the equation (4).

After calculating the estimated output voltage El' in this way,
The processing circuit 26 refers to the map 28 in the memory circuit 27 and calculates the estimated output voltage El in step 5).
The output voltage Ego corresponding to ' is accessed, and the alcohol concentration C at the position where El'=EIO is determined and calculated as the true alcohol concentration.

Then, the obtained true alcohol concentration C is outputted to the fuel injection amount calculation device 29, alcohol concentration meter 30, etc., and the process returns again.

Thus, according to this embodiment, the first and second
The output voltage El, E from the alcohol senna 11.17
2 can be used to calculate the alcohol concentration before change over time, so even if alcohol-mixed gasoline changes over time due to various factors, these factors can be abstracted to determine the true alcohol concentration. can.

In addition, in the embodiment, steps 1 to 4 in FIG. 6 are specific examples of the voltage value calculation means according to the present invention, steps 5 and 6 are specific examples of the alcohol concentration calculation means, and furthermore, the map 2
8 is a specific example of the storage means, but the present invention is not limited to these specific examples.

Also, 1st. Regarding the second alcohol sensor 11゜17, in order to make the specifications different, the second alcohol sensor 1
Although the parallel resistor 23 is inserted in the electrode 18.
19, the surface area of the electrodes, the applied voltage of the DC power supply 21, etc. may be changed. The second alcohol sensor 11.17 may also have a reverse configuration.

Furthermore, although alcohol-mixed gasoline is illustrated as an alcohol-mixed liquid, the present invention can be applied to other alcohol-containing liquids.

〔Effect of the invention〕

The present invention has been described in detail above, and the first invention has different specifications. Since the second alcohol sensor is used to calculate the voltage value before the change over time, and based on this voltage value, the alcohol concentration is calculated from the pre-stored voltage value before the change over time. Accurate concentration measurements can be made without being affected by factors.

[Brief explanation of the drawing]

1 to 7 show embodiments of the present invention, and FIG. m1 is the first embodiment of the present invention. A layout diagram showing the second alcohol sensor placed in the fuel pipe, Figure 2 is a circuit diagram showing the first alcohol sensor, Figure 3 is a circuit diagram showing the second alcohol sensor, and Figure 4 is the main alcohol sensor. A block diagram showing an arithmetic device of an embodiment,
FIG. 5 is a diagram showing the relationship between the alcohol concentration before time-dependent changes stored in the map and the output voltage, FIG. 6 is a flowchart showing the alcohol concentration calculation process by the arithmetic unit, and FIG. Characteristic diagram showing the relationship between alcohol concentration and output voltage before and after change over time regarding the second alcohol senna, No. 8
12 to 12 relate to the prior art, FIG. 8 is a characteristic diagram showing the relationship between the air-fuel ratio and the alcohol concentration, FIG. 9 is a layout diagram showing the prior art alcohol sensor arranged in a fuel pipe, and FIG. Figure 10 is a circuit diagram showing the alcohol sensor, Figure 11 is a characteristic line diagram showing the relationship between alcohol concentration and detection resistance, and Figure 12 is a characteristic line diagram showing the relationship between alcohol concentration and output voltage before and after changes over time. be. DESCRIPTION OF SYMBOLS 11... First alcohol sensor, 17... Second alcohol sensor, 12, 13, 18.19... Electrode, 14.20... Detection circuit, 16.22... Detection resistor, 23...Parallel resistance, 24...Arithmetic device, 28.
...Matsupu. Patent applicant Kazuhiko Hirose, agent for Uhon Electronics A Co., Ltd., patent attorney
Naoki Nakamura Figure 1 Figure 2 Figure 3 Figure 4 , 4 Figure 5 Figure 6 Alcohol 1 note C (''/,) Figure 9 Figure 10 Figure 11

Claims (1)

[Claims] The first alcohol concentration detection means detects the alcohol concentration in the liquid containing alcohol based on the resistance value between the electrodes and outputs it as a voltage signal, and the first alcohol concentration detection means is configured with different specifications. a second alcohol concentration detection means for detecting the alcohol concentration in the liquid based on the resistance value between the electrodes and outputting it as a voltage signal; and a voltage signal from the first and second alcohol concentration detection means. a voltage value calculation means for calculating a voltage value before a change over time based on the first alcohol concentration detection means; and a voltage value calculation means for calculating a voltage value before a change over time based on the first alcohol concentration detection means, and a change over time outputted from the mixed alcohol concentration and the first alcohol concentration detection means regarding the liquid. and alcohol concentration calculation means for calculating the alcohol concentration over time by referring to the storage means based on the voltage value calculated by the voltage value calculation means. A resistance-type alcohol concentration measuring device.