JP2571465B2 - Gasoline property identification device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a gasoline property discriminating apparatus suitable for discriminating heavy, medium, light, etc. properties of gasoline used for automobile engines and the like. .

[Conventional technology]

Generally, pure gasoline used as fuel for automobile engines includes light gasoline mainly containing hydrocarbons such as heptane and pentane, heavy gasoline mainly containing hydrocarbons such as benzene, and heavy gasoline. There is medium-grade gasoline that is located between high-grade gasoline and light-grade gasoline. Light gasoline has the property of being easily vaporized, while heavy gasoline has the property of being hardly vaporized.

In a gasoline engine used for an automobile engine, ignition timing and the like are usually set in accordance with light gasoline.

[Problems to be solved by the invention]

By the way, as described above, a gasoline engine is adapted to control ignition timing and the like of the engine by matching with light gasoline. However, the use of heavy gasoline has recently become popular, and the use of heavy gasoline has been increasing due to reasons such as the enforcement of the Air Pollution Law.

However, if heavy gasoline is used as fuel in a gasoline engine that is set to match light gasoline to control the ignition timing of the engine, the ignition timing is delayed compared to light gasoline, As a result, there is a problem in that the leanness tends to increase, and the startability and drivability at low temperatures deteriorate. Further, even in a running state, when heavy gasoline is used, there is a problem that not only deterioration of driving performance such as a breathing phenomenon occurs, but also harmful components in exhaust gas increase due to incomplete combustion.

On the other hand, contrary to the above, when light gasoline is used for a gasoline vehicle that is set to control ignition timing and the like by matching heavy gasoline, the overall tendency becomes overrich, and the There is a problem that "smoldering" occurs.

In order to solve such a problem, the present applicant has previously filed Japanese Utility Model Application No. Hei 2-49724 (Japanese Utility Model Application Laid-open No. Hei 4-8956), which is disposed in gasoline and determined according to the properties of the gasoline. Capacitance detecting means for detecting the capacitance between the electrodes from the ratio, oscillating means for oscillating a frequency based on the capacitance detected by the capacitance detecting means, and oscillating frequency by the oscillating means to a voltage A gasoline property comprising frequency-to-voltage conversion means for converting, and property determination means for comparing a voltage signal output from the frequency-to-voltage conversion means with a predetermined voltage value to determine whether the gasoline is light gasoline or heavy gasoline. A (heavy and light) discriminator has been proposed (hereinafter referred to as prior art).

With such a configuration, since heavy gasoline has a higher dielectric constant between light gasoline and heavy gasoline, the capacitance formed between the electrodes due to the inherent dielectric constant by the capacitance detecting means. The oscillation means generates a frequency based on the detected capacitance, the frequency-voltage conversion means converts the oscillation frequency into a voltage, and the property judgment means compares this voltage signal with a predetermined comparison voltage value, Can be determined.

Meanwhile, commercially available genuine gasoline sometimes contains an alcohol such as methanol, ethanol, or MTBE (methyl tert-butyl ether) as an additive. When alcohol is mixed into the genuine gasoline in this manner, the dielectric constant is increased by the alcohol, so that the output voltage increases according to the mixing ratio of the additive as shown in FIG.

However, in the prior art gasoline property discriminating apparatus, since the output voltage is only compared with a predetermined comparison voltage value, for example, as shown in FIG. When the detected sensor output voltage V is V ₀ , there are three states: pure pure gasoline only, medium gasoline with 5% additive, and light gasoline with 10% additive. It may be detected, and even if the gasoline property is actually heavy gasoline, it will be determined as medium or light gasoline according to the mixing ratio of the additive, and the exact state of pure heavy gasoline will be determined. There is an unsolved problem that it cannot be detected.

The present invention has been made in view of the above-mentioned unsolved problems of the prior art. Even when gasoline contains an additive (alcohol), it has properties as a pure heavy gasoline, light and medium quality. Property determination device that accurately determines the properties of gasoline as high-quality gasoline (including the case where the gasoline is lightened due to the addition of additives to heavy gasoline) and enables appropriate engine control The purpose is to do.

[Means for solving the problem]

In order to solve the above-mentioned problems, a gasoline property discriminating apparatus adopted by the present invention includes a capacitance-type gasoline property detection sensor whose output voltage changes according to properties of light, medium, and heavy gasoline, A first determination for determining whether the region is light, medium or heavy gasoline based on a relationship between an output voltage from the gasoline property detection sensor and a temperature detected by the temperature sensor; Means, and when the first determination means determines that the gasoline property is in the heavy gasoline region, the output voltage of the gasoline property detection sensor is determined from the output voltage of the gasoline property detection sensor at different detection temperatures of the temperature sensor. Temperature gradient calculating means for calculating the temperature gradient of the gasoline, and the temperature in the heavy gasoline region is reduced by the temperature gradient calculated by the temperature gradient calculating means.
And a second determining means for determining whether the gasoline is medium-grade gasoline or pure heavy gasoline.

[Action]

With the above configuration, the first determination means determines whether the gasoline is light, medium, or heavy gasoline based on the relationship between the output voltage from the gasoline property detection sensor and the detected temperature. As described above, even when the first determination unit determines that the gasoline is in the heavy gasoline region, the heavy gasoline may include light and medium gasoline due to the influence of the additive. Therefore, the temperature gradient is calculated by the temperature gradient calculating means from different output voltages from the gasoline property detection sensors at different detected temperatures, and the second determining means determines that the heavy gasoline region is light and medium in the heavy gasoline region. It is determined whether the high quality gasoline is genuine heavy gasoline. Thus, it is possible to determine whether the heavy gasoline region determined by the first determination unit is genuine heavy gasoline.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 7.

First, in FIG. 1, reference numeral 1 denotes, for example, a four-cylinder engine (only one cylinder is shown).
And a cylinder head 1B mounted on the cylinder 1A,
A piston 1C reciprocates in the cylinder 1A. Reference numeral 2 denotes an ignition plug (only one is shown) provided on the cylinder head 1B located above each cylinder 1A. The ignition plug 2 is used when a control unit 21 described later outputs an ignition signal. The mixture in 1A is burned (exploded).

Reference numeral 3 denotes an intake manifold provided on the intake side of the cylinder head 1B of the cylinder 1 with a base end serving as a branch pipe. An intake filter 4 is provided on the distal end side of the intake manifold 3, and an intake air amount is provided in the middle. , A throttle valve 7 provided with a throttle valve switch 6, and the like, and an injection valve 8 is provided near the cylinder head 1B. Gasoline is injected into the engine 1 by an injection signal.

Reference numeral 9 denotes a fuel tank for storing gasoline G therein. Inside the fuel tank 9, an in-tank type fuel pump 10 is provided. Reference numeral 11 denotes a fuel pipe. One end of the fuel pipe 11 is connected to a discharge side of the fuel pump 10 via a fuel filter 12, and the other end is connected to an injection valve 8 and an inflow side of a pressure regulator 13. Is connected to the fuel tank 9 via a return pipe 14.

Reference numeral 15 denotes, for example, a gasoline property detection sensor provided in the middle of the fuel pipe 11, and the gasoline property detection sensor 15 detects a change in the dielectric constant due to the property state of the gasoline G flowing in the fuel pipe 11 as a voltage. .

Here, as shown in FIG. 2, the gasoline property detection sensor 15 is composed of a pair of parallel plate type or coaxial same tube type electrodes provided in the fuel pipe 11, and in the case of a parallel plate type electrode, C = ε ₁ S ₁ / d ₁ (1) where ε ₁ : dielectric constant of gasoline S ₁ : electrode area d ₁ : distance between electrodes Capacitance detector
The oscillation frequency f is calculated based on the capacitance C detected by Here, L: inductance Co: an LC type oscillation circuit 17 oscillating as a capacitance of the circuit, and a frequency − that converts an oscillation frequency f from the oscillation circuit 17 into a detection voltage V.
Voltage conversion circuit 18 (hereinafter referred to as “f / V conversion circuit 18”)
And inverts and amplifies the detection voltage V from the f / V conversion circuit 18,
The circuit is roughly composed of an inverting amplifier circuit 19 that outputs an output voltage V. Each of the circuits 17, 18, and 19 is composed of an electronic component.

Here, the main component of hydrocarbons in gasoline G differs depending on the place of production, and the induction rate ε of the hydrocarbons (specific induction rate ε
₀ ) is as shown in the table below.

For this reason, the capacitance C between the electrodes by the capacitance detector 16
Has a characteristic as shown in FIG. 3 in proportion to the properties of pure gasoline, and the voltage E detected by the f / V conversion circuit 18 via the oscillation circuit 17 has a characteristic as shown in FIG. By inverting and amplifying the detection voltage E by the inverting amplifier circuit 19, a characteristic having an output voltage V as shown in FIG. 5 is obtained. Thus, the output voltage V having the characteristics shown in FIG. 5 can be obtained from the gasoline property detection sensor 15 in accordance with the heavy and light properties of pure gasoline.

Next, reference numeral 20 denotes a temperature sensor as a temperature sensor provided near the gasoline property detection sensor 15. Here, since the fuel temperature of the gasoline G changes due to the heat of the engine 1 while circulating between the fuel tank 9 and the engine 1, the temperature sensor 20 detects the fuel of the gasoline G flowing through the fuel pipe 11. The temperature is output to a control unit 21 described later as a detection signal.

Reference numeral 21 denotes a control unit used in the present embodiment. The control unit 21 is constituted by, for example, a microcomputer or the like, and the control unit 21 is a RAM,
And a memory circuit 22 comprising M
A property determination processing program, a fuel injection amount calculation program, and an ignition timing control program shown in the figure (all not shown)
And so on. Further, the temperature characteristic maps 23 and genuine judgment temperature gradient alpha ₀ of heavy gasoline quality detecting sensor 15 shown in FIG. 6 is stored in the memory circuit 22.

Here, the temperature characteristic map 23 shown in FIG. 6 indicates the temperature t (hereinafter referred to as the heat temperature t) of the gasoline G of heavy, medium, and light gasoline.
This shows the characteristics of the output voltage V from the property detection sensor 15 in the present embodiment, and in this embodiment, the determination region A for heavy gasoline is set. The predetermined temperature gradient α ₀ indicates a temperature gradient of pure heavy gasoline.

On the input side of the control unit 21, in addition to the air flow meter 5, the throttle valve 7, the crank angle sensor 24 for detecting the number of revolutions of the engine 1, the gasoline property detection sensor 15, the temperature sensor 20, the engine switch 25, etc. Various sensors such as a sensor and an oxygen sensor are connected, and an ignition plug 2, an injection valve 8, and the like are connected to an output side.

The present embodiment is configured as described above, and its operation will be described next with reference to the gasoline property determination processing in FIG.

First, in step 1, the state of the engine switch 25 is read, and in step 2, it is determined whether or not the engine switch is ON. If "YES", the flow proceeds to step 5, and if "NO", the flow proceeds to step 3. In step 3, the counter i is reset (i = 0), and the process ends in step 4.

Determines "YES" in the step 2, if it proceeds to step 5, since the engine 1 in step 5 is activated, reads the fuel temperature t _i from the temperature sensor 20, in step 6 gasoline property detection reads the output voltage V _i from the sensor 15, the temperature characteristic map in the memory circuit 22 in the next step 7
The heavy area A is read from 23.

Now, it is determined to perform the next step 8 broad decision, that is obtained from the read elaborate fuel temperature t _i and the output voltage V _i is, whether the heavy region A of the temperature characteristic map 23 . If "YES" is determined in this step 8, this point is within the heavy area A because the point is within the heavy area A, and if "NO" is determined, this point is outside the heavy area A. To step 9. Then, in step 9, the gasoline G is determined to be medium or light gasoline, and stored in the storage circuit 22, and the process proceeds to step 15. In this step 15, the fuel temperature t _i is replaced with t _i−1 and stored, and in step 16 the output voltage V _i is replaced with V _i−1 and stored. Further, in step 17, the counter i is incremented by "1". Then, the process returns in step 18.

On the other hand, if it is determined “YES” in step 8 described above, it is determined in step 10 whether the counter i is “0”,
If "YES" is determined, it is the first program cycle, so the process proceeds to step 15, and returns from step 18 in the same manner as described above. If "NO" is determined, the process proceeds to step 11. It is moving.

By the way, if it is determined "NO" in step 10, the second
Because it is the second program cycle, step
The calculation of the temperature gradient α according to 11 is performed. That is, it is determined that the point obtained from the output voltage V _i and fuel temperature t _i is loaded in step 8 described above is present in heavy region A, in the heavy gasoline in this wide determination In addition, light gasoline exists while containing additives (alcohol).

Therefore, in step 11, the difference between the fuel temperature t _i and the output voltage V _i read this time and the difference between the fuel temperature t _i-1 and the output voltage V _i-1 in the previous program cycle stored in steps 16 and 17 are calculated. Based on the temperature gradient α, Is calculated as And in the next step 12, step
It is determined whether or not the temperature gradient α calculated in 11 is larger than the determination temperature gradient α ₀ of the genuine heavy gasoline stored in the storage circuit 22. That is, when it is determined to be “NO” in step 12, the temperature gradient α is equal to the determination temperature gradient α ₀ of the pure heavy gasoline.
Therefore, it is determined that the gasoline G is medium or light gasoline, and the process proceeds to step 13 to store this in the storage circuit 22, and then proceeds to step 15. On the other hand, "YES" in step 12
Is determined, the temperature gradient α is larger than the determination temperature gradient α ₀ of pure heavy gasoline, so that the gasoline G can be determined to be pure heavy gasoline, and the process proceeds to step 14 where it is stored in the storage circuit 22. Go to step 15.

As a result, in the control unit 21, the storage circuit 22
Memory circuit according to the state of gasoline G stored in
The fuel injection amount calculation process and the ignition timing control process built in 22 are divided into pure heavy gasoline and medium and light gasoline.

As described above, according to the present embodiment, the gasoline G is different from the pure heavy gasoline with the pure heavy gasoline from the difference in the output voltage V obtained by the difference in the dielectric constant depending on the property and the characteristic of the fuel temperature t. When judging light gasoline, even when alcohol such as an additive is contained in gasoline G, it is configured to judge pure heavy gasoline with the influence of the alcohol being removed. A highly accurate gasoline property determination device can be provided. As a result, the ignition advance angle and the retard angle are corrected according to the properties of the gasoline G, and the fuel injection amount is corrected to prevent over-lean and over-rich, thereby providing appropriate material conditions. Therefore, as described in the prior art, even when the ignition timing of the engine is matched with light gasoline, when using pure heavy gasoline, this ignition timing can be corrected to the ignition timing corresponding to this heavy gasoline, and the ignition timing can be corrected. Thus, problems such as incomplete combustion due to misalignment can be solved, and harmful components in exhaust gas can be effectively reduced.

Steps 5 to 8 in the program shown in FIG. 7 are specific examples of the first determining means according to the present invention.
11 to 14 are specific examples of the second determination means according to the present invention.
Further, the first determination means is determined based on the heavy region A of the map 23, but may be determined based on the comparison voltage value as in the above-described prior art.

In addition, an inverting amplifier circuit 19 is provided in the gasoline property detection sensor 15.
However, a non-inverting amplifier circuit may be used.

Furthermore, although the gasoline property detection sensor 15 and the temperature sensor 20 of the present embodiment have been described as being provided in the middle of the fuel pipe 11, for example, they may be provided in the fuel tank 9; It may be a place.

〔The invention's effect〕

The gasoline property determination device according to the present invention is as described in detail above, and uses a dielectric constant determined according to the property of gasoline, and outputs from a capacitance-type gasoline property detection sensor whose output voltage changes. From the output power and the temperature detected by the temperature sensor for detecting the temperature of the gasoline, the first determination means determines whether the gasoline is in the light, medium gasoline or heavy gasoline region. When it is determined that the gasoline is in the heavy gasoline region, the temperature gradient of the output voltage is calculated from the output voltage of the gasoline property detection sensor at different detected temperatures by the temperature gradient calculating means, and the temperature gradient is calculated by the second determining means. Is designed to determine whether the gasoline is genuine heavy gasoline or light / medium gasoline. Therefore, even if the gasoline contains additives (alcohol) etc. The determination by the determination unit, heavy gasoline region or genuine heavy gasoline, light, medium petrol of determination can be performed accurately, the control process of the engine can be performed accurately.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram when an embodiment of the present invention is applied to a fuel injection control device, FIG. 2 is a block diagram showing a circuit configuration of this embodiment, and FIG. Fig. 4 shows the relationship between gasoline properties and f /
FIG. 5 is a diagram showing the relationship between the detected voltages from the V conversion circuit, FIG. 5 is a diagram showing the relationship between the gasoline properties and the output voltage from the inverting amplifier circuit, and FIG. FIG. 7 is a flow chart showing the control processing by the control unit, and FIG. 8 is a characteristic diagram of the output voltage with respect to the gasoline properties of pure gasoline and gasoline mixed with an additive. 15, Gasoline property detection sensor, 16 Capacitance detector, 17 Oscillation circuit, 18 Frequency-voltage conversion circuit, 19
…… Inverting amplifier circuit, 20 …… Temperature sensor (temperature sensing sensor),
21: Control unit, A: Heavy area, α:
Temperature gradient, α ₀ ... Determination temperature gradient of pure heavy gasoline.

Claims (1)

(57) [Claims] 1. A capacitance type gasoline property detection sensor whose output voltage changes according to the properties of light, medium and heavy gasoline, a temperature-sensitive sensor for detecting the temperature of the gasoline, and the gasoline. First determining means for determining whether the gasoline is light, medium gasoline or heavy gasoline based on the relationship between the output voltage from the property detection sensor and the temperature detected by the temperature sensor; If it is determined that the temperature of the gasoline property detection sensor is different from the temperature of the gasoline property detection sensor at a different detection temperature, a temperature gradient calculation means for calculating a temperature gradient of the output voltage of the gasoline property detection sensor; A second determining means for determining whether the heavy gasoline region is light, medium gasoline or pure heavy gasoline based on the temperature gradient calculated by the gradient calculating means. Gasoline property determination device.