JPH04213057A - Fuel-property detecting apparatus - Google Patents

Abstract

PURPOSE:To prevent the occurrence of erroneous detection caused by the decrease in rotation due to the action of an external load by using a fuel- property detecting apparatus for an engine which detects and judges the volatility of fuel based on the decreasing characteristic of the rotation of the engine. CONSTITUTION:An inhibiting means H, which inhibits the detecting operation of a fuel-property detecting means B for detecting the volatility of fuel based on the decrease and fluctuation of the rotation of an engine when the acting state of an external load is detected with an external-load detecting means D, is provided.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine fuel property detection device for detecting fuel volatility from changes in engine speed.

0002

[Prior Art] In recent years, engine fuels, especially gasoline, have become commercially available with low volatility, and when fuels with different fuel properties are supplied to an engine and combusted, various control characteristics can be changed using this type of fuel. It is necessary to make corrections in response to changes in fuel properties.

In other words, when a heavy fuel with low volatility is supplied, the various control characteristics that have been set up to that point for normal fuel will cause the fuel to deteriorate, especially during cold driving when the engine temperature is low. Evaporation and atomization decrease, resulting in poor running performance. On the other hand, if the fuel properties are detected and determined based on the volatility of the fuel, the fuel increase during cold operation can be corrected to increase by a predetermined amount based on the detection of the fuel properties. It becomes possible to improve.

[0004] Therefore, in order to detect and judge the fuel properties such as the volatility of the above-mentioned fuel, for example, Japanese Patent Laid-Open No. 1983-1999 has been used.
As seen in Publication No. 288335, fuel properties are detected and determined based on the in-cylinder pressure detected by a pressure sensor, based on the fact that heavy fuel and normal fuel have different combustion speeds, that is, pressure rises during combustion in the cylinder. Techniques that do this are well known.

[0005]Furthermore, since the air-fuel ratio of low-volatility fuel decreases during acceleration, it is conceivable to detect the air-fuel ratio using an air-fuel ratio sensor and determine the fuel properties.

[0006]

[Problem to be Solved by the Invention] However, in the above-mentioned system in which the volatility of fuel is detected from the fluctuation characteristics of the cylinder pressure in the engine, it is necessary to separately install a pressure sensor for this purpose. Yes, it is disadvantageous in terms of cost. Also,
If the volatility of the fuel is determined from the change in the air-fuel ratio during acceleration, the detection and determination cannot be made before the vehicle is running, and a reduction in drivability is inevitable until the detection is made.

On the other hand, it is preferable to detect fuel volatility using signals from existing sensors, such as changes in engine rotation. This is preferable because the amount of fuel that is heated and vaporized by the surrounding temperature is small, and the true volatility of the fuel can be detected, but this engine rotation fluctuates in response to various conditions, so It is difficult to perform highly accurate detection unless engine rotational fluctuations due to differences are distinguished from engine rotational fluctuations due to other factors.

In other words, when detecting and determining changes in fuel volatility from the characteristics of a decrease in engine speed, an alternator that can handle increases in driving load of an air conditioner compressor, driving load of an oil pump for power steering, and electrical load is required. When an external load such as a torque converter load is applied due to an increase in the drive load of the automatic transmission or a shift to a driving range such as the D range of the automatic transmission, the engine speed decreases due to this as well. Identification may not be possible and false detection may occur.

Therefore, in view of the above-mentioned circumstances, the present invention provides an engine fuel property detection device which prevents the occurrence of false detection due to the operation of an external load when detecting and determining fuel volatility based on the decreasing characteristic of engine rotation. The purpose is to provide

0010

[Means for Solving the Problems] In order to achieve the above object, the engine fuel property detection device of the present invention, as shown in the basic configuration in FIG. A rotation detecting means A is provided, and a signal from the engine rotation detecting means A is outputted to a fuel property detecting means B. The fuel property detecting means B detects the volatility of the fuel based on the decreasing fluctuation of the engine rotation. Further, the engine E is provided with an external load C whose operation increases the driving load acting on the engine E, and an external load detection means D is provided for detecting the operating state of the external load C. In response to the signal from the external load detecting means D, a prohibiting means H is provided which prohibits the fuel property detecting means B from detecting the volatility of the fuel when the external load C is in an operating state.

[0011] The external load C includes drive loads such as an air conditioner compressor, a power steering oil pump, an alternator, and an automatic transmission.

0012

[Operation and Effect] In the fuel property detection device as described above, when an external load is operating, detection of fuel volatility is prohibited even if other fuel volatility detection conditions are met. This prevents the occurrence of false detection of volatility due to a drop in rotation due to the operation of an external load, and performs appropriate control in response to volatility based on accurate detection of fuel properties. It is something that can be done.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. FIG. 2 is an overall configuration diagram of an engine equipped with a fuel property detection device according to an embodiment.

An intake port 4 and an exhaust port 5 are opened in communication with a combustion chamber 3 formed above the piston 2 of the engine body 1 so as to have a variable volume. It is opened and closed.

An intake passage 8 connected to the intake port 4
is equipped with an air flow sensor 11 and a throttle valve 12 that detect the amount of intake air from the upstream side, and a surge tank 1.
A downstream portion of the cylinder 3 is branched into each cylinder, and an injector 14 for injecting and supplying fuel is disposed there.

Further, a bypass air passage 15 is formed in the intake passage 8, which bypasses the throttle valve 12 and is connected to the intake passage 8 above and below the intake passage 8. A control valve 16 is provided to adjust the amount of air. Further, an ignition plug 17 is disposed facing the combustion chamber 3, and a discharge voltage is applied to the ignition plug 17 via an ignition coil 18 and a distributor 19 to adjust the ignition timing.

A control signal is output from the controller 20 to the ignition coil 18 and the control valve 16 of the bypass air passage 15 to perform ignition timing control and bypass air control. Furthermore, the injector 14
Fuel injection control is performed according to the operating state using control signals from the controller 20.

In order to detect the operating state, the controller 20 receives a rotation signal from the distributor 19 for detecting the engine rotation speed, an intake air amount signal from the air flow sensor 11, an engine water temperature signal from the water temperature sensor 22, and a signal from the throttle valve 12. A signal from the idle switch 23 that operates in the fully closed state, a signal from the shift sensor 24 that detects the neutral state of the transmission (in the case of a manual transmission),
A signal from the starter switch 25 that starts the starter, a signal from the air conditioner switch 27 to detect the operating state of an external load, a signal from the power steering switch 28 according to the operation of the power steering, a signal from the electric load switch 2
9, a range position signal from the inhibitor switch 30 (in the case of an automatic transmission), etc. are inputted.

Further, the controller 20 has the function of the fuel property detecting means B for detecting and determining a signal related to fuel volatility from the decreasing fluctuation of the engine speed during a predetermined period immediately after the engine is started, and It has the function of inhibiting means H that determines the operating state of the load and prohibits fuel volatility detection when the external load is operating.

In addition, in the fuel injection control by the controller 20, if it is detected that the fuel used at the time of starting the engine is a heavy fuel with low volatility, an increase in the amount of fuel supplied during cold conditions (warm-up amount increase) is performed. It is configured to perform correction control in which the amount increases and decreases as the engine water temperature rises, and correction to increase the amount of acceleration increase during acceleration.

Specifically, the fuel properties are determined by detecting changes in the engine speed after cold starting, and a time chart thereof will be explained based on FIG. 3. When starting the starter motor at point a and starting cranking to start the engine, the engine speed begins to rise and increases further when the fuel is ignited and reaches a complete explosion state, and then decreases once after starting. The engine speed shifts to the engine speed (target value No.) corresponding to the engine water temperature, throttle opening, etc.

[0022] In the state of decrease from point b, heavy fuel has low fuel volatility and a lean air-fuel ratio compared to normal fuel, so the rate of decrease is fast, so that the engine speed decreases to a predetermined rotation speed Nc. If the rotation speed drops below the set rotation speed Nd after a predetermined time t, it is determined that heavy fuel is being supplied. In addition, even if the rate of decrease in the engine speed is slower than the above conditions, the engine speed may be lower than the lower limit rotation speed N.
3, it is also determined that heavy fuel is being supplied.

The processing of the controller 20 will be explained with reference to the flowcharts of FIGS. 4 and 5. This FIG. 4 shows a fuel property determination routine, in which after control start, various signals are read in step S1, and in steps S2 to S7 it is determined whether fuel property detection conditions for determining fuel volatility are satisfied. Determine.

First, in step S2, the starter switch 2
It is determined whether or not a predetermined time (approximately 60 seconds) has passed since the switch 5 was turned on. Outside of this period, there is a high possibility of false detection due to rotation fluctuations due to load fluctuations in response to changes in operating conditions. Therefore, volatility detection is performed only during this period.

Further, in step S3, it is determined whether the engine water temperature Tw is in a cold state within a predetermined range Ta to Tb. The lower limit temperature Ta is about 0° C., and in a region lower than this temperature, the combustion state is unstable, and even with normal fuel, the rotational speed decreases greatly, increasing the possibility of false detection. On the other hand, the upper limit temperature Tb is about 40
The temperature is ~60°C, and during a warm start that is higher than this temperature, the fuel is warmed and vaporized, and there is little difference in vaporization between heavy fuel and normal fuel, and there is little increase in fuel quantity, and even with normal fuel, the engine speed decreases after it increases. Since this increases the possibility of false detection, volatility detection is performed only in the predetermined range Ta to Tb.

Further, in step S4, it is determined whether or not the starter switch 25 is on and the starter is operating during cranking, and during cranking, even if the engine is started, the rotational speed is low and the lower limit rotational speed N3 is reached. Volatile detection should not be performed because the following may occur.

Next, in step S5, it is determined whether the throttle valve 12 is fully closed, and in step S6, it is determined whether the throttle valve 12 is in the neutral state. Throttle valve 1
2 is fully closed and in neutral, volatile detection is performed.

On the other hand, in step S7, it is determined whether or not the external load is turned on based on the signals from the air conditioner switch 27, power steering switch 28, electric load switch 29, and inhibitor switch 30. The operating state is when the air conditioner compressor is operating and its driving load is acting, when the driving load of the oil pump for power steering is acting in response to steering operation, and when the electric power such as headlamp lighting is being applied. This occurs when the drive load on the alternator increases in response to an increase in load, or when the torque converter load is acting on the automatic transmission due to shifting to a driving range such as D range. When the engine is running, the rotation will drop and there is a high possibility of false detection, so volatile detection is not performed.

[0029] When the above fuel property detection conditions are satisfied, volatility detection and determination are performed in steps S8 to S17. First, in step S8, the engine speed N is 1250 r.
It is determined whether or not it has become equal to or less than pm (Nc). If this determination is YES, it is determined in step S9 whether or not the previous engine rotation speed Ni-1 was higher than 1250 rpm. If this judgment is also YES and the engine speed N becomes 1250 rpm or less for the first time, step S1
0, the timer t is set to a predetermined time (for example, 2 seconds).

[0030] Thereafter, in response to a decrease in the engine speed N, if the determination in step S9 is NO, the process proceeds to step S11, where the timer t is decremented, and in step S12, it is determined whether or not the timer t has reached 0. This step S1
When the determination in step 2 is YES and a predetermined period of time has elapsed, it is determined in step S13 whether or not the engine speed has decreased to 1000 rpm (Nd) or less, and if this determination is YES, the predetermined time t is Since the rotational speed has decreased to a predetermined value or more during this period, it is determined that the volatility of the fuel is low, and in step S15, the fuel flag G is set to 1 and a heavy fuel determination is performed. On the other hand, even if the predetermined time t has passed, 1
If the speed has not decreased below 000 rpm, it is determined that the volatility of the fuel is not low, and the fuel flag G is set to 0 in step S16.

[0031]Also, even if it is not determined that the fuel is heavy fuel due to the decrease in engine speed N at the predetermined time t, the engine speed N itself is lowered to the lower limit rotation speed N in step S14.
3 (for example, 500 rpm), it is determined that the fuel is heavy and the fuel flag G is set to 1 in step S15.

[0032] When this heavy weight determination is completed, step S1
The determination completion flag F is set to 1 in step S18.
This routine ends based on the judgment of
Until then, the detection continues with a NO determination in step S18.

Next, in the fuel control routine shown in FIG. 5, after the control is started, various signals are read in step S21, and based on these, the basic injection amount Tp is calculated in step S22. This basic injection amount Tp is a fuel amount corresponding to an intake air filling amount obtained by dividing the intake air amount by the engine rotational speed and multiplying the result by a count.

Then, in step S23, it is determined whether or not the fuel flag G is set to 1. If the volatility of the fuel set to 1 is low, in step S24, the warm-up increase coefficient Cw is set to 1. Warm-up increase coefficient Cw1 for fuel
On the other hand, in the case of normal fuel with the fuel flag G reset to 0, the warm-up increase coefficient Cw is set to the warm-up increase coefficient Cw2 for normal fuel in step S25. The warm-up increase coefficients Cw1 and Cw2 are set corresponding to the engine water temperature Tw, as shown in FIG. The fuel increase is set to be large, and the warm-up increase coefficient Cw1 for heavy fuel is set.
is set larger than the warm-up increase coefficient Cw2 for normal fuel, and increases the fuel increase in a state where the volatility of the fuel is low.

Further, step S26 is for determining the acceleration state based on changes in throttle opening, etc. When the acceleration exceeds a predetermined value, it is determined in step S27 whether or not the fuel flag G is set to 1. In a state where the volatility of the fuel is low, the acceleration increase coefficient Cacc is changed to the acceleration increase coefficient Cacc1 for heavy fuel in step S28.
On the other hand, in the case of normal fuel which has been reset to 0, the acceleration increase coefficient Cacc is set to the acceleration increase coefficient Cacc2 for normal fuel in step S29. Furthermore, if the determination in step S26 is NO and there is no acceleration,
In step S30, the acceleration increase coefficient Cacc is set to zero. Then, the acceleration increase coefficient Cacc1 for the heavy fuel
is set to a larger value than the warm-up increase coefficient Cacc2 for normal fuel, and corrects the air-fuel ratio becoming lean during acceleration due to its low volatility.

Step S31 is a feedback correction value,
Other correction amounts Ce such as learning values are calculated, and the final injection pulse T is calculated in step S32 based on this correction amount Ce, the basic injection amount Tp, the warm-up increase coefficient Cw, and the acceleration increase coefficient Cacc. In step S33, the result is output to the injector 14 to inject a predetermined amount of fuel.

[0037] Due to the above-mentioned action, when detecting and determining the volatility of the fuel based on the decreasing characteristic of the engine speed within a predetermined period after a cold start, the external load is activated when detecting the fuel properties. In this case, volatile detection judgment is prohibited to prevent false detection, and volatile detection is also prevented under other conditions where a drop in rotational speed occurs that is not due to fuel volatility. The fuel properties can be detected with high reliability based on the detected fuel properties, and based on the detected fuel properties, the warm-up fuel increase and the acceleration fuel increase can be corrected to ensure good running performance.

[Brief explanation of the drawing]

[Fig. 1] Basic configuration diagram of an engine fuel property detection device of the present invention.

FIG. 2 is a schematic configuration diagram of an engine equipped with a fuel property detection device according to an embodiment of the present invention.

[Fig. 3] Explanatory diagram showing an example of fluctuation in engine speed when detecting fuel properties

[Fig. 4] Main part flowchart diagram for explaining the gravity determination process of the controller

[Fig. 5] Main part flowchart for explaining fuel control processing of the controller

[Figure 6] Characteristic diagram showing the setting characteristics of the warm-up increase correction coefficient

[Explanation of symbols]

1 Engine body 8 Intake passage 12 Throttle valve 20 Controller A Engine rotation detection means B Fuel property detection means D External load detection means H Prohibited means

Claims (1)

[Claims] Claims: 1. A fuel property detector comprising: engine rotation detection means for detecting fluctuations in engine rotation; and fuel property detection means for detecting volatility of the fuel based on fluctuations in decrease in engine rotation using a signal from the engine rotation detection means. The detection device includes an external load detection means for detecting the operating state of an external load acting on the engine, receives a signal from the external load detection means, and detects the fuel property detection means when the external load is in the operating state. A fuel property detection device characterized in that it is provided with a prohibition means for prohibiting the detection of volatility of the fuel.