JPH0396844A - Arithmetic unit for temperature correction of alcohol concentration - Google Patents

Abstract

PURPOSE:To allow the computation for temp. correction of an alcohol concn. over the entire region by holding the alcohol concn. at a prescribed concn. value if concn. data does not exist in a selected concn. map at the time of computing the alcohol concn. in accordance with a detected electric signal quantity. CONSTITUTION:This unit has an alcohol concn. detecting means 101, an alcohol concn. computing means 106, a concn. data presence/absence deciding means 105, etc.. The alcohol concn. computing means 106 computes the alcohol concn. by using the detected electric signal quantity and the concn. map 1 when the concn. data presence/absence deciding means 105 decides that the alcohol concn. data corresponding to the selected concn. map 1 exists in accordance with the detected electric signal quantity from the alcohol concn. detecting means 101. On the other hand, the alcohol concn. is held at the prescribed concn. value by an alcohol concn. holding means 107 when the absence of the alcohol concn. data is decided. The region where the alcohol concn. cannot be computed is eliminated in this way and the temp. correction is surely executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an alcohol concentration temperature correction calculation device that is applied to, for example, a fuel injection amount calculation device for an engine using alcohol mixed fuel.

[Prior Art] Recently, alcohol-mixed gasoline has come to be used as fuel for automobile engines instead of genuine gasoline.

Naturally, the octane number will differ between genuine gasoline and alcohol-mixed gasoline, so the fuel injection amount, ignition timing, etc. of the engine will also differ.

Here, the fuel injection amount T. when using genuine gasoline with an alcohol concentration of 0%. Looking at it, T+=Tpxα
×α′×Col, f+T8...(l) However, TP
: Basic injection amount α : Air-fuel ratio feedback correction coefficient α′ : Basic air-fuel ratio learning correction coefficient Coat : Various correction coefficients Ts : Calculated as battery voltage correction coefficient. At this time, based on the oxygen concentration signal from the oxygen sensor, the air-fuel ratio fi and de-back correction coefficient α are corrected, and the basic air-fuel ratio learning correction coefficient α' is corrected by learning from the basic injection amount TP and engine speed N. As a result, the stoichiometric air-fuel ratio A/F is controlled to 14.7.

In this way, the air-fuel ratio A/F of genuine gasoline is 14.7, but when using methanol with an alcohol concentration of 100%, it is necessary to control the air-fuel ratio A/F to 65. When the alcohol concentration is in the range of 0 to 100%, the stoichiometric air-fuel ratio A/F will differ by about twice.

Therefore, when using alcohol-mixed gasoline,
From equation (1), calculate the fuel injection amount T1' as TI = CK x TP
Xα×α′×Coet+Ts (2) However, CX: It is necessary to calculate as a constant determined by the alcohol concentration.

Thus, in engines that use alcohol-mixed gasoline, the alcohol concentration in the fuel is detected by an alcohol sensor, which detects the alcohol concentration from the specific resistance value that gasoline and alcohol have. A resistive alcohol sensor, a capacitive alcohol sensor that uses changes in the dielectric constant of alcohol-mixed gasoline, an optical alcohol sensor that uses changes in the amount of transmitted light, etc. can be used.

By the way, the methanol content in alcohol-mixed gasoline has flow rate dependence in its physical and scientific properties, and its resistance value and dielectric constant change with temperature changes. For this reason,
When the output voltage is measured using a resistive alcohol sensor, capacitive alcohol sensor, etc., the characteristics of the alcohol concentration and the alcohol sensor output voltage are as shown in Figure 6. This characteristic changes. That is, M20℃, M30 in FIG.
°C, M40 °C means that the flame d is 20 °C, 30 °C, 40 °C, respectively.
It shows the relationship between alcohol concentration M and alcohol sensor output voltage E at ℃.

For this reason, in the alcohol concentration measuring device according to the prior art, a thermistor is attached to the alcohol sensor as a temperature detection sensor, and on the other hand, a characteristic diagram corresponding to the fuel temperature as shown in Fig. 6 is installed in the control unit for calculating the alcohol concentration. (Hereinafter, the relationship between the alcohol concentration M determined for each fuel temperature and the alcohol sensor output voltage E is referred to as a "concentration map").Then, a concentration map is created based on the detected fuel temperature from the thermistor. is selected, and using the selected concentration map, the alcohol concentration is calculated with the temperature corrected using the output voltage from the alcohol sensor as an address, so that the required detection accuracy is within ±10%.

Problem to be solved by invention C] However, although the thermistor has negative characteristics as shown in Figure 5, this thermistor is composed of semiconductor components, and the output voltage characteristics may vary depending on manufacturing errors, material, etc. It is known that variations as shown by symbols A and B in FIG. 5 occur.

For this reason, if a concentration map is selected using the output voltage characteristics of a certain thermistor used and the alcohol concentration is calculated while correcting the temperature, there may be areas where temperature correction calculations cannot be performed, or the required accuracy of ±10% may be exceeded. It turned out that there was an unresolved problem.

That is, in order to correct the alcohol concentration by temperature, the relationship between thermistor detection temperature t and thermistor output voltage E is used, and thermistor A having characteristic A in FIG. 5 is used as a standard thermistor, and the temperature as shown in FIG. Assume that map A has been created. On the other hand, the thermistor used was B, and the fifth
Assume that it is characteristic B in the figure.

As a result, the thermistor B used generates an output voltage Vu, and the detected temperature ta (for example, tB
= 20°C). However, the control unit uses the temperature map A to calculate the detected temperature tA (for example, tn40'C) from the output voltage (18), and selects the depth map M40°C of 40°C. However, assuming that the actual fuel temperature is 30°C, the alcohol sensor will generate an output voltage E with the characteristic M30°C in FIG. For this reason, from the alcohol sensor E(
When an output voltage E greater than the output at 100% alcohol concentration is generated at a degree map M40°C, the alcohol concentration? The problem is that it cannot be calculated accurately.

Contrary to the above, thermistor B with characteristic B in FIG.
Assume that a temperature map B as shown in FIG. 5 is created using the standard thermistor.

On the other hand, assume that the thermistor used is A and has the characteristic A in FIG.

As a result, the thermistor A used generates an output voltage ■c, and the detected temperature tA at that time (for example, tA=
40°C). However, the control unit uses the temperature map B to calculate the detected temperature ti (for example, ta=20°C) from the output voltage Vx, and selects the concentration map M20°C of 20°C. However, assuming the actual fuel temperature is 30°C, the alcohol sensor
An output voltage is generated with the characteristic M 3 0 'C in the figure. For this reason, E2 from the alcohol sensor
When the output voltage E (output at the alcohol concentration of 100% when the concentration map M is 30° C.) is generated, there is a problem that the alcohol concentration appears as an error by ΔM in FIG. 6.

The present invention has been made in view of the problems of the prior art, and aims to eliminate the area where alcohol concentration cannot be calculated based on the amount of electrical signal detected by the alcohol concentration detection means, and to ensure temperature correction. An object of the present invention is to provide an alcohol concentration temperature correction calculation device.

[Means for Solving the Problems] In order to achieve the above object, the present invention detects the alcohol concentration in the body of the subject as an electrical signal amount, as shown in the functional block diagram of FIG. Alcohol concentration detection means 1
01, a temperature detection means 102 that detects the temperature of the liquid to be measured as an electrical signal amount, and an alcohol concentration and the alcohol concentration detection means 101 corresponding to the temperature of the liquid to be measured.
a concentration map in which one of the alcohol concentration maps 103 is selected based on the alcohol concentration map 103 having a relationship with the electric signal amount detected by the temperature detection means 102 and the electric signal amount detected by the temperature detection means 102; The selection means 104 refers to one concentration map selected by the concentration map selection means 104 based on the amount of electric signal detected by the alcohol concentration detection means 101, and detects the electric signal detected in the one concentration map. Concentration data presence/absence determining means 105 for determining whether or not alcohol concentration data corresponding to the amount exists; and concentration data presence/absence determining means 1
05, when it is determined that alcohol concentration data exists, alcohol concentration calculation for calculating the alcohol concentration from one concentration map selected by the concentration map selection means 104 and the electrical signal amount detected by the alcohol concentration detection means 101; means 106, and concentration holding means 107 for holding the alcohol concentration at a determined concentration value when the concentration data presence/absence determining means 105 determines that alcohol concentration data does not exist.
It is composed of.

[Operation] With this configuration, the concentration map selection means 10
4 to select one density map. When the concentration data presence/absence determining means 105 determines that corresponding alcohol concentration data exists in the selected one concentration map based on the amount of electric signal detected from the alcohol concentration detecting means 101, the alcohol concentration l-value calculating means 106 detects the presence or absence of alcohol concentration data. Alcohol concentration is calculated using the electrical signal amount and one concentration map. On the other hand, when the concentration data presence/absence determining means 105 determines that alcohol concentration data does not exist, the concentration holding means 107 holds the alcohol concentration at a predetermined concentration value.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to FIGS. 2 to 4.

In FIG. 2, reference numeral 1 denotes an alcohol concentration calculation device that is composed of, for example, a CPU, an MPU, etc., and calculates the alcohol concentration while correcting the temperature through the processing described later. A storage device 2 is attached to constitute a control unit, and the storage device 2 stores a mixture map 3 related to the thermistor 5, which will be described later, and an alcohol concentration map 4 related to the alcohol sensor 6, as shown in FIG. Flowcharts are stored as programs. Here, in the temperature map 3, the thermistor detected temperature t and thermistor output voltage (2) are stored as the characteristics of the standard thermistor, similar to that explained with reference to FIG. Also, in the alcohol concentration map 4, the relationship between the alcohol concentration M and the alcohol sensor output voltage E is, for example, 20'C, 30°C, 40°C, .
Concentration map for each...4M2 0℃, 4M30℃,
It is stored as 4M40℃,...

On the other hand, 5 is a thermistor for detecting the fuel temperature in the fuel supply pipe, and 6 is an alcohol sensor for detecting the alcohol concentration in the alcohol-mixed gasoline flowing in the fuel pipe. is connected to the input side of the alcohol concentration calculation device 1. Here, as the alcohol sensor 6, for example, a resistance type alcohol sensor is used, and the thermistor 5 is attached to the alcohol sensor 6. The resistance-type alcohol sensor has a pair of flat electrodes installed in the fuel supply pipe, and detects a change in the resistance value of the alcohol-mixed gasoline interposed between the electrodes as a voltage signal amount.

Reference numeral 7 denotes an injection amount calculation device constituted by, for example, a microcomputer, and the input side of the injection amount calculation device 7 includes an alcohol concentration calculation device 1, a crank angle sensor 8, an airflow make 9, an oxygen sensor, and a hydrogen sensor (all not shown). figure)
etc., and the output side is connected to an injection valve 10 that injects fuel into the engine. Here, the injection amount calculation device 7 calculates the basic injection amount Tp based on the engine rotation speed N from the crank angle sensor 8 and the intake air ffiQ from the air flow meter 9, and also calculates the basic injection amount Tp.
In addition to the alcohol concentration M from T1', the fuel injection amount ``r,'' is calculated by equation (2) based on the signals from various sensors, and an injection pulse with a pulse duty corresponding to this fuel injection amount T1' is injected. It outputs to the valve 10.

The present embodiment is configured as described above, and the temperature correction calculation process for alcohol concentration will be described based on FIG.

First, when the process starts, the alcohol concentration calculation device 1 reads the output voltage ■ from the thermistor 1 in step 1, reads the temperature map 3 in the storage device 2 in the next step 2, and reads the thermistor corresponding to the output voltage V. Determine the detected temperature t. Next, in step 3, the alcohol concentration map 4 in the storage device 2 is read out, and the alcohol concentration map 4 is read out using the detected temperature t determined in step 3 as an address.
Select one of the density maps. For example, assuming that the thermistor-detected temperature t is 40°C, a concentration map 4M of 40°C is selected from among the alcohol concentration maps 4 and determined. Note that steps 1 to 3 in FIG. 4 are specific examples of the density map selection means according to the present invention.

Next, the alcohol concentration calculation device l moves to step 4 and reads the output voltage E from the alcohol sensor 6, and in step 5, concentration data corresponding to the output voltage E is present in the concentration map selected in step 3. Determine whether or not to do so. That is, in the case of the above-mentioned specific example, if one concentration map selected in step 3 is 4M40°C, concentration data regarding alcohol concentration M corresponding to output voltage E exists in the concentration map 4M40°C. As explained earlier in FIG. 6, the density map M
At 40°C, the alcohol concentration is 100% when the alcohol sensor output voltage E is E, and the output voltage E is E1.
If it is larger, no concentration data exists.

In this way, when rYEsJ is determined in step 5,
That is, when it is determined that there is concentration data corresponding to the alcohol sensor output voltage E in the selected one concentration map, the process moves to step 6, and when it is determined that rNOJ is present,
Since the alcohol concentration cannot be calculated, the process moves to step 7. Therefore, step 5 constitutes a specific example of the density data presence/absence determining means according to the present invention.

Next, when rYESJ is determined in step 5 as described above, proceed to step 6, use the selected concentration map of ~, and use the alcohol sensor output voltage E read in step 4 as an address to create the concentration map of the concerned one. The alcohol concentration M corresponding to the output voltage E is calculated.

The calculated alcohol concentration M is then output to the injection amount calculation device 7. Note that step 6 is a specific example of the alcohol concentration calculation means according to the present invention.

Furthermore, when it is determined in step 5 that rNOJ, there is no concentration data corresponding to the alcohol sensor output voltage E in the selected concentration map, and alcohol concentration calculation is impossible. Although various reasons can be considered for this, it is thought that the characteristic relationship between the thermistor output voltage (2) and the detected temperature t of the thermistor 5 actually used varies with respect to the standard thermistor. Therefore, in this case, a process is performed to hold the alcohol concentration M at 90%, and M=90% is output to the fuel injection device 7. Therefore, step 7 is a specific example of the alcohol concentration holding means according to the present invention.

As described above, according to this embodiment, one concentration map is selected based on the temperature t detected by the thermistor 5, and the alcohol degree M is calculated based on the selected concentration map. This alcohol concentration M can always be calculated as a temperature-corrected value. Furthermore, if there is no concentration data corresponding to the alcohol sensor output voltage E in the concentration map in step 5, the alcohol concentration M is held at 90% in step 7, so the concentration calculation is impossible. Also, the alcohol concentration M can be output to the injection amount calculation device 7. As a result, the injection amount can be calculated and controlled, thereby preventing the worst case scenario of engine stall. Furthermore, each concentration map of alcohol concentration map 4...4M2 0℃, 4M3
By appropriately setting concentration data such as 0℃, 4M40℃, etc., the required accuracy of alcohol concentration detection can be ±10.
% range.

In addition, although the thermistor 5 was illustrated as the temperature detection means in the embodiment, a thermosensor or other temperature sensing element may be used.

In addition, alcohol concentration map 4, 16, has been described assuming that each concentration map is created in units of 10°C, but 5°C. It may be prepared in units of 1°C. Furthermore, the alcohol concentration held in step 7 is 90%.
Of course, it is not limited to.

〔Effect of the invention〕

The alcohol concentration temperature correction calculation device according to the present invention is as described in detail above, and selects a concentration map from the temperature detected by the temperature detection means, and uses the selected one concentration map to detect the temperature detected by the alcohol concentration detection means. When calculating the alcohol concentration based on the detected electric signal amount, if there is no concentration data in the selected concentration map, the alcohol concentration is held at a predetermined concentration value.
Even if there are variations in the temperature detected by the temperature detection means, it is possible to prevent the occurrence of regions in which alcohol concentration calculations are impossible, and to enable temperature correction calculations of alcohol concentration over the entire region, thereby achieving high accuracy. Concentration detection can be performed.

[Brief explanation of drawings]

FIG. 1 is a functional block diagram showing the configuration of the present invention, FIGS. 2 to 4 are embodiments of the present invention, and FIG. 2 is a block diagram showing the circuit configuration of this embodiment. An explanatory diagram showing a map stored in the storage device in the figure, FIG. 4 is a flowchart showing the temperature correction calculation process of this embodiment, and FIGS.
The figures relate to the prior art; FIG. 5 is a diagram showing the relationship between the temperature detected by the thermistor and the thermistor output voltage, and FIG. 6 is a diagram showing the relationship between the alcohol concentration and the alcohol sensor output voltage. 1... Alcohol concentration calculation device, 2... Storage device,
3... Temperature map, 4... Alcohol concentration map,
5...Thermistor, 6...Alcohol sensor, 7.
... Injection amount calculation device, 10... Injection valve.

Claims (1)

[Claims] an alcohol concentration detection means for detecting the alcohol concentration in the liquid to be measured as an electric signal amount; a temperature detection means for detecting the temperature of the liquid to be measured as an electric signal amount; select one of the alcohol concentration maps based on the relationship between the alcohol concentration map and the electric signal amount detected by the alcohol concentration detection means, and the electric signal amount detected by the temperature detection means; density map selection means for
Referring to one concentration map selected by the concentration map selection means based on the electric signal amount detected by the alcohol concentration detection means, alcohol concentration data corresponding to the electric signal amount detected in the one concentration map. and when the concentration data presence/absence determining means determines that alcohol concentration data exists, one concentration map selected by the concentration map selection means and the alcohol concentration detection alcohol concentration calculation means for calculating alcohol concentration from the amount of electrical signal detected by the means; and concentration hold for holding the alcohol concentration at a predetermined concentration value when the concentration data presence/absence determination means determines that alcohol concentration data does not exist. An alcohol concentration temperature correction calculation device comprising means.