JPH06100113B2 - Fuel injection control device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a fuel injection control device applied to an engine using alcohol-blended fuel.

[Conventional technology]

Generally, genuine gasoline is used as fuel for automobile engines, but alcohol-mixed gasoline in which alcohol consisting of methanol is mixed may be used. And when comparing genuine gasoline and alcohol mixed gasoline, the octane number naturally changes, so the fuel injection amount, ignition timing, etc. of the engine will also differ, and the engine for alcohol mixed fuel will be installed. There is.

Here, regarding the basic injection amount T _P when using genuine gasoline, when the intake air amount is Q, the engine speed is N, and the constant is K, the basic injection amount T _P is T _P = K × Q / N …… (1) is calculated. Then, the basic injection amount T _P is corrected based on signals from various sensors such as a water temperature sensor and an oxygen sensor, various switches such as an engine switch and a throttle valve switch, and finally the fuel injection amount Ti by the injection valve Ti
Ti = T _P × α × α '× C _OEF + T _S (2) where α: Air-fuel ratio feedback correction coefficient α': Basic air-fuel ratio learning correction coefficient C _OEF : Various correction coefficients T _S : Battery voltage correction Calculate as a coefficient. At this time, the air-fuel ratio feedback correction coefficient α is corrected based on the enzyme concentration signal from the oxygen sensor, and the basic air-fuel ratio learning correction coefficient α ′ is learned and corrected from the basic injection amount T _P and the engine speed N. , Air-fuel ratio (weight ratio of air and fuel) A / F is controlled to be 15: 1.

In this way, the air-fuel ratio A / F of corrected gasoline is 15: 1, but the air-fuel ratio of alcohol-blended gasoline has the characteristics shown in Fig. 6, and the air-fuel ratio becomes 100% when the alcohol concentration is 100%.
It is known to be 6: 1.

Therefore, when using alcohol blended gasoline,
From the equation (2), the fuel injection amount Ti is Ti = C _K × T _P × α × α '× C _OEF + T _S (3) where C _K is a constant determined by the alcohol concentration.

Here, as the alcohol sensor for detecting the alcohol concentration in the alcohol-blended gasoline, a resistance-type alcohol sensor for detecting the alcohol concentration from the specific resistance value of gasoline and alcohol, and the alcohol concentration from the dielectric constant in the alcohol-blended gasoline are detected. Capacitive alcohol sensors, optical alcohol sensors that utilize the amount of transmitted light, and the like are being studied. Among these alcohol sensors, for example, as shown in FIG. 7, a resistance type alcohol sensor has a pair of electrodes b and c, which are opposed to each other with a predetermined distance apart in the middle of a pipe a which is a flow path. Based on the fact that the resistance value decreases as the alcohol concentration of the alcohol-blended gasoline d interposed between b and c decreases (see FIG. 8), the electrodes b and c and the voltage detection resistance e are connected in series to the DC power supply f. Then
The alcohol concentration is detected from the change in the output voltage E derived from the voltage detection resistor e.

That is, since the resistance values of the electrodes b and c decrease as the alcohol concentration C increases, the output voltage E from the voltage detection resistance e becomes
As shown in FIG. 9, it can be derived as a detection voltage that is directly proportional to the alcohol concentration C.

[Problems to be Solved by the Invention]

By the way, in an automobile using alcohol-blended gasoline, there is a difference of about 3 times in the air-fuel ratio between 6: 1 and 15: 1 depending on the alcohol concentration.

On the other hand, when the alcohol sensor fails, the output voltage E having the characteristic shown by the solid line in FIG. 9 cannot be output, and as shown by the dotted line in FIG. 9, regardless of the alcohol concentration,
A predetermined lower limit voltage E ₁ or less when the alcohol concentration is 0% or an upper limit voltage E ₂ or more when the alcohol concentration is 100% may be output. Here, the lower limit voltage E ₁ is a value lower than the normal output voltage when the alcohol concentration C is 0%, and the upper limit voltage E ₂ is the alcohol concentration C of 10%.
A value higher than the normal output voltage at 0%.

As described above, when the alcohol sensor fails and the normal detection voltage cannot be output, the fuel injection amount calculated by the equation (3) is calculated.
I can't calculate Ti. That is, when the detection voltage is equal to or lower than the lower limit voltage E ₁ , the gasoline concentration is calculated as 100%, and conversely, when the detection voltage is equal to or higher than the upper limit voltage E ₂ , the alcohol concentration is calculated as 100%.
As a result, normal engine control cannot be performed,
There is a problem that safe driving is hindered and causes an accident.

To solve such a problem, the alcohol concentration when the alcohol sensor is operating normally is stored, and the fuel injection amount is controlled by fixing the alcohol concentration at the normal state even after the alcohol sensor fails. You can drive and drive the car.

However, when alcohol-blended gasoline with different alcohol concentrations is refueled, such as when driving a long distance, or when 100% methanol alcohol or genuine gasoline is refueled, the alcohol concentration in the fuel tank changes significantly. As a result, a new problem arises in that the proper injection amount control cannot be performed.

The present invention has been made in view of such unsolved problems of the prior art, and enables highly accurate fuel injection control even when new fuel is refueled after the alcohol concentration detection means has failed. It is an object of the present invention to provide a fuel injection control device of the type.

[Means for Solving the Problems]

In order to achieve the above object, the present invention, as shown in the functional block diagram of FIG. 1, includes a fuel tank for storing an alcohol mixed fuel, a fuel pump for discharging the fuel in the fuel tank, and a fuel pipe. In a fuel injection control device including an injection valve for injecting fuel supplied from the fuel pump into an engine, a remaining amount detecting means for detecting a remaining amount in the fuel tank, the fuel tank, the fuel pump, and a fuel pipe. And an alcohol concentration detecting means provided at a desired position in the fuel supply system for detecting the alcohol concentration in the fuel, and the concentration detected by the alcohol concentration detecting means deviates from a normal detection range, and the alcohol concentration detecting means is Failure determination means for determining whether or not there is a failure, and whether or not refueling is performed after the failure determination means determines that the alcohol concentration detection means has failed When it is determined that refueling has been performed by the refueling determination means and the refueling determination means, the remaining amount before refueling detected by the remaining amount detection means, the current remaining amount after refueling, and alcohol or gasoline only in advance Alcohol concentration calculating means for calculating the alcohol concentration of the new fuel from the determined refueling oil type and the alcohol concentration before the failure detected by the alcohol concentration detecting means, and the alcohol of the new fuel calculated by the alcohol concentration calculating means It is characterized by comprising a failure injection control means for performing fuel injection control by the injection valve based on the concentration.

[Action]

With this configuration, when the failure determination means determines that the alcohol concentration detection means has failed, the refueling determination means determines that the fuel of the predetermined oil type, which is alcohol or gasoline, is refueled. ,
The alcohol concentration calculation means calculates the alcohol concentration of the new fuel in the fuel tank, and the failure injection control means calculates the fuel injection amount based on the calculated alcohol concentration and operates the injection valve.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 2 to 5.

2 to 4 show a first embodiment of the present invention.

In the figure, reference numeral 1 denotes an automobile engine, and the engine 1
Is provided with an injection valve 2 for injecting alcohol-mixed gasoline into the combustion chamber, an intake manifold 3 for inhaling outside air, and an air flow meter 5 for measuring the amount of intake air between the intake filter 4 and the intake filter 4. ing. Further, the engine 1 is provided with an exhaust manifold 6, and the exhaust manifold 6 is provided with an oxygen sensor (not shown).

7 is a fuel tank for storing alcohol mixed gasoline F,
A fuel pump 8 that discharges the alcohol-mixed gasoline F is provided in the fuel tank 7.

Reference numeral 9 denotes a float type fuel gauge attached to the fuel pump 8. The fuel gauge 9 detects the remaining amount of the alcohol mixed gasoline F stored in the fuel tank 7. In addition,
The fuel gauge 9 may be configured to output a detection signal according to the remaining amount Q in the fuel tank 7 regardless of the shape of the fuel tank 7, and detect only the liquid level of the fuel tank 7. Alternatively, it may be combined with a remaining amount calculation circuit that separately calculates the remaining amount Q in the tank.

Reference numeral 10 denotes a fuel pipe. One end of the fuel pipe 10 is connected to the discharge side of the fuel pump 8, the other end is connected to the injection valve 2, the inflow side of the pressure regulator 11, and the fuel filter 1
2, the alcohol sensor 13 is provided. On the other hand, the outflow side of the pressure regulator 11 is connected to the fuel tank 7 via a return pipe 14. Here, the alcohol sensor 13 is for detecting the alcohol concentration in the alcohol mixed gasoline 8 flowing in the fuel pipe 10 and outputting the output voltage E. The alcohol sensor 13 is, for example, shown in FIG. A resistance type alcohol sensor or the like is used. Further, the pressure regulator 11 guides the pressure in the intake manifold 3 as a control pressure to control so that the difference between the fuel pressure and the pressure in the intake manifold 3 is always constant.

Further, reference numeral 15 is an arithmetic unit constituted by a microcomputer or the like, and the arithmetic unit 15 is an input / output control circuit 16 as shown in FIG. 3, for example, a processing circuit 1 constituted by a CPU, MPU or the like.
7, a storage circuit 18 including, for example, a ROM and a RAM. The input side of the input / output control circuit 16 has various sensors such as an air flow meter 5, a fuel gauge 9, an alcohol sensor 13, a crank angle sensor 19, an oxygen sensor, a water temperature sensor, a vehicle speed sensor, an engine switch, a throttle valve switch, and a shift. It is connected to various switches such as switches and a battery (neither is shown), and the output side is an injection valve
2, It is connected with the alarm 20 etc. Here, the alarm 20
Not only informs the failure of the alcohol sensor 13, but at the time of the next refueling (at the time of refueling when it is judged as a failure), refueling only one predetermined oil type consisting of pure alcohol or gasoline only. This is for informing what should be done, and for example, a refueling liquid type instruction lamp, a voice informing device by voice synthesis, or the like is applied, and is usually provided in the cab.

The memory circuit 18 stores a program for injection amount calculation processing shown in FIG.
A is a detection voltage E with respect to the current alcohol concentration, a predetermined lower limit voltage E ₁ when the alcohol concentration is 0%, a predetermined upper limit voltage E ₂ when the alcohol concentration is 100%, a remaining amount value Q ₀ of the previous program cycle, When Q ₀ ′, the alcohol sensor 13 fails, the remaining amount Q ′ before refueling at the start of refueling is stored.

Further, the arithmetic unit 15 has a basic injection amount calculation function of calculating the basic injection amount T _P of the equation (1) based on the intake air amount Q from the air flow meter 5 and the engine speed N from the crank angle sensor 19, and the alcohol. The output voltage E corresponding to the detected alcohol concentration C from the sensor 13 is used to calculate the fuel injection amount Ti from the equation (3), and the output voltage E of the alcohol sensor 13 is stored for each program cycle. A failure determination function for determining whether or not the alcohol sensor 13 has failed by comparing with E ₁ or the upper limit voltage E _2, and when it is determined that the alcohol sensor 13 has failed, the stored alcohol concentration C immediately before the failure is stored. A failure injection amount calculation function for performing fuel injection control by fixing to (output voltage E), a failure notification function for activating the alarm device 21 when the alcohol sensor 13 fails, and a residual alarm function. A refueling start determination function that determines whether refueling is started based on a change in the value Q, a function that stores the remaining amount value Q before that when refueling is started, and a remaining amount value Q ′ after refueling Change determination function for determining whether or not refueling is completed, when refueling is completed, a remaining amount value Q'before refueling, an actual refueling amount (Q'-Q),
Refueling oil type notified by alarm 20 and alcohol sensor
It has an alcohol concentration calculating function for calculating the alcohol concentration C of the new fuel from the output value E of 13 and a function for calculating the injection amount from the equation (3) based on the calculated alcohol concentration.

The present embodiment is constructed in this way, and its operation will be described next with reference to FIG.

First, when the engine switch is turned on and the processing is started, in step 1, the arithmetic unit 15 reads the output voltage E from the alcohol sensor 13 under the control of the processing circuit 17.
Then, in the next step 2, the arithmetic unit 15 determines the engine speed N from the crank angle sensor 19 and the air flow meter 5
The intake air amount Q from is read to calculate the basic injection amount T _{P according} to equation (1), and the output voltage E (alcohol concentration C) read in step 1 and other signals from various sensors, switches, etc. Based on this, the fuel injection amount Ti of the alcohol mixed gasoline is calculated, and an injection pulse having a pulse duty corresponding to this fuel injection amount Ti is output to the injection valve 2. As a result, the alcohol mixed gasoline F in the fuel tank 7
Is supplied to the injection valve 2 via the fuel pump 8, the fuel pipe 10, the fuel filter 12, the alcohol sensor 13, etc., and drives the engine 1. The process of step 2 performed as described above is the normal injection control.

In this way, after performing the normal injection control in step 2, in the next step 3, the storage area 18A of the storage circuit 18 is
The output voltage E from the alcohol sensor 13 read in step 1 is stored therein. Then, in the next step 4, the output voltage E is compared with the lower limit voltage E ₁ and the upper limit voltage E ₂ stored in the storage area 18A, and the output voltage E is within the range of these respective voltages E ₁ , E ₂ . If it is within the range, it is determined that the alcohol sensor 13 is operating normally, the process returns to step 1 and the normal injection control is performed. On the other hand, the output voltage E is the lower limit voltage E ₁
If it is less than or equal to the upper limit voltage E ₂ , it is determined that the alcohol sensor 13 has failed because the alcohol concentration is an output voltage outside the range of 0 to 100%. Thus,
Step 4 constitutes the failure determination means of the present invention.

If it is determined in step 4 that the alcohol sensor 13 has failed, the process proceeds to the next step 5, in which the fuel injection amount Ti calculated by the equation (3) is calculated from the output voltage E stored in the storage area 18A of the storage circuit 18 immediately before the failure. Calculate this fuel injection amount
Fix to Ti. That is, the fact that the alcohol sensor 13 has failed means that normal injection control cannot be performed, but since the output voltage E in the program cycle before the failure is stored in step 3, fuel is newly supplied. Unless otherwise, the alcohol concentration of the alcohol mixed gasoline F in the fuel tank 7 is considered to be the same as the value based on the output voltage E. Therefore, in step 5, the fuel injection amount Ti of the equation (3) is calculated by the alcohol concentration C stored immediately before the failure, and the injection control is fixed.

Further, after the process of step 5 is performed, the process proceeds to the next step 6 to output an operation signal to the alarm device 20 to inform the driver that the alcohol sensor 13 has failed and that only alcohol or only gasoline should be refueled.

Next, when the processes of steps 5 and 6 are completed, the remaining amount value Q is read from the remaining amount meter 9 in the next step 7, and the remaining amount value Q ₀ in the previous program cycle is read from the memory circuit 18 in step 8. In step 9, the difference ΔQ = Q−Q ₀ between the two is compared to determine whether or not there is a change in the remaining amount value Q. If there is no difference between the two, the remaining amount value Q read in step 7 is set in the previous program in step 10. The remaining amount value Q ₀ in the cycle is stored in the storage area 18A, and the process returns to step 5. On the other hand, if the difference ΔQ between the present detected remaining amount value Q and the remaining amount value Q ₀ in the previous program cycle is greater than or equal to a predetermined value in step 9, it is determined that refueling has started.

Next, when "YES" is determined in step 9, the refueling work has been started, so the process moves to step 11 to store the pre-refueling remaining amount value Q in the storage area 18A. Then, in step 12, the remaining amount value Q'after refueling is started is read from the fuel gauge 9, the remaining amount Q ₀ 'in the previous program cycle is read in step 13, and the difference ΔQ' between the two is read in step 14.
= Q′−Q ₀ ′ is compared to see if the remaining amount value Q ′ is constant. If the difference between the two is greater than or equal to a predetermined value, it is determined that refueling is in progress and the remaining amount value Q ′ read in step 12 In step 15, the storage area 18 is set as the remaining amount value Q ₀ ′ in the previous program cycle.
Store in A and return to step 12. On the other hand, in step 14, the detected remaining amount Q ′ of this time and the remaining amount value in the previous program cycle.
If the difference ΔQ ′ from Q ₀ ′ is less than or equal to a predetermined value, it is determined that refueling has ended. Therefore, steps 7 to 15 are specific examples of the refueling determination means according to the present invention.

When it is determined in step 14 that refueling is completed, the process proceeds to step 16, and the remaining amount value Q before refueling stored in step 11, the actual refueling amount (= Q'-Q) accompanying refueling this time, and the alarm
The alcohol concentration C of the new fuel after refueling is calculated based on the predetermined refueling oil type notified in step 20, the output value E before the failure of the alcohol sensor 13 stored in step 3, and the like.
Therefore, step 16 constitutes the alcohol concentration calculating means of the present invention.

Further, when the calculation in step 16 is performed, step 17
In the same manner as in the case of calculating the fuel injection amount in step 2, based on the calculated alcohol concentration C of the new fuel, the fuel injection amount Ti of the alcohol-mixed gasoline after refueling is calculated by the equations (1) and (2), An injection pulse having a pulse duty corresponding to the fuel injection amount Ti is output to the injection valve 2. As a result, the new alcohol-mixed gasoline F in the fuel tank 7 is converted into the fuel pump 8, the fuel pipe 10, and the fuel filter 1.
2, supplied to the injection valve 2 via the alcohol sensor 13 and the like,
The engine 1 is driven. Therefore, step 17 constitutes the injection control means at the time of failure of the present invention.

Thus, when the alcohol of the type of oil or gasoline notified by the alarm device 20 is refueled in the processing of steps 9 to 15, the alcohol concentration of the new fuel after refueling can be accurately calculated by the processing of step 16. Therefore,
Even if the fuel tank 7 is refueled after the alcohol sensor 13 has failed, injection control based on accurate alcohol concentration is also possible, and highly accurate control is possible, as well as engine stall accidents due to overrich or over lean. Etc. can be prevented and safety can be improved.

Next, FIG. 5 shows a second embodiment of the present invention. The feature of the present embodiment is that in a vehicle type in which a cap switch is provided at the fuel filler port of the fuel tank 7, the refueling determination is performed using the cap switch. The means has been configured.

That is, in FIG. 5, the signal from the cap switch is read after the alarm device 20 is activated in step 26, and when the switch signal is output in step 28, it is determined that refueling is started, while in step 32 the switch signal is output. When it is stopped, it is determined that the refueling is completed.

Although the present embodiment is configured in this way, it has the same effect as the first embodiment.

In addition, although the resistance type alcohol sensor is exemplified as the alcohol concentration detecting means of the present invention in the embodiment, a capacitance type alcohol sensor or the like may be used, and in this case, the lower limit output voltage of the capacitance type alcohol sensor is used. It suffices to make a failure determination from the upper limit output voltage.

〔The invention's effect〕

The fuel injection control device according to the present invention is as described above in detail, and constantly monitors whether or not the alcohol concentration detecting means has failed, and when the alcohol concentration detecting means has failed, whether or not refueling has been performed is performed. Since the alcohol concentration of the new fuel is calculated by the alcohol concentration calculating means when the fuel is monitored and a predetermined oil type is supplied after the breakdown, the fuel injection control at the time of the breakdown is performed. Accurate injection control can be performed even if the means is out of order, and sudden engine stop accidents caused by a large change in the air-fuel ratio can be prevented in advance to ensure safe driving of the vehicle. You can

[Brief description of drawings]

FIG. 1 is a functional block diagram showing the configuration of the present invention, FIGS. 2 to 4 relate to a first embodiment of the present invention, and FIG. 2 is an overall configuration diagram of a fuel injection control device according to the present embodiment, FIG. 3 is a block diagram showing a circuit configuration, FIG. 4 is a flow chart showing an injection amount calculation process, FIG. 5 is a flow diagram showing an injection amount calculation process according to a second embodiment of the present invention, and FIGS. FIG. 6 relates to the prior art, FIG. 6 is a diagram showing the relationship between alcohol concentration and air-fuel ratio, FIG. 7 is a configuration diagram showing a specific configuration of a resistance type alcohol sensor, and FIG. FIG. 9 is a diagram showing the relationship with the resistance, and FIG. 9 is a diagram showing the relationship between the alcohol concentration and the output voltage. 1 ... Engine, 2 ... Injection valve, 7 ... Fuel tank, 8
...... Fuel pump, 9 ... Fuel gauge, 10 ... Fuel piping, 13 ...
… Alcohol sensor, 15 …… Computing device, 20 …… Alarm.

Claims (1)

[Claims] 1. A fuel tank for storing an alcohol-mixed fuel, a fuel pump for discharging the fuel in the fuel tank, and an injection valve for injecting the fuel supplied from the fuel pump through a fuel pipe to an engine. In the fuel injection control device, a remaining amount detecting means for detecting the remaining amount in the fuel tank and a fuel supply system including the fuel tank, the fuel pump, and the fuel pipe are provided at a desired position to control the alcohol concentration in the fuel. An alcohol concentration detecting means for detecting, a failure determining means for determining whether or not the alcohol concentration detecting means has deviated from a normal detection range and the alcohol concentration detecting means has a failure, and the failure determining means is an alcohol Refueling determination means for determining whether or not refueling has been performed after determining that the concentration detection means has failed, and refueling is performed by the refueling determination means. When it is determined that the remaining amount before the refueling detected by the remaining amount detecting means and the current remaining amount after refueling, a predetermined refueling oil type consisting of alcohol or gasoline only, and the alcohol concentration detecting means are detected. When an alcohol concentration calculating means for calculating the alcohol concentration of the new fuel from the alcohol concentration before the failure and a fuel injection control by the injection valve based on the alcohol concentration of the new fuel calculated by the alcohol concentration calculating means A fuel injection control device comprising an injection control means.