JPS61226531A - Fuel supply device of engine - Google Patents

Abstract

PURPOSE:To continually maintain air-fuel ratio of a mixture to a proper value, by detecting an octane number of gasoline in an engine, which can use plural kinds of gasoline having the different octane number, and controlling a supply quantity of fuel in accordance with a detection value. CONSTITUTION:A fuel tank 40 mounts an octane number detecting sensor 50 detecting an octane number of gasoline in the tank, and a control unit 100 inputs a detection signal of said sensor. The control unit 100, inputting various operative condition detection signals of an engine 10, controls a fuel injection valve 20 to inject fuel in accordance with an operative condition. Additionally the control unit decreases an injection quantity of fuel, when the gasoline has a high octane number, smaller than that when the gasoline has a low octane number. In this way, air-fuel ratio of a mixture can be always controlled to a proper value in no relation to the octane number of the supplied gasoline.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a fuel supply system for an engine that supplies fuel according to the operating state of an engine that can use multiple types of gasoline with different octane numbers as fuel. Regarding equipment.

(Prior Art) In addition to so-called regular gasoline, high-octane gasoline with a higher octane number is used as fuel in automobile gasoline engines.

This high-octane gasoline contains a larger amount of aromatic components than regular gasoline, which are difficult to thermally decompose, therefore difficult to cause self-ignition phenomenon, and have stable combustion characteristics (in general, aromatic components The content ratio of group components is set to be 40% or more in high octane gasoline and less than 40% in regular gasoline). Therefore, when high octane gasoline is used as fuel for a gasoline engine, the occurrence of knocking is suppressed compared to when regular gasoline is used, so high octane gasoline is used, It becomes possible to operate the engine by setting the ignition timing so as to obtain the highest thermal efficiency under a predetermined compression ratio.

For this reason, when there is a possibility that regular gasoline and high octane gasoline are used in one engine, it has been considered to set appropriate ignition timings for each gasoline.

For example, Japanese Patent Application Laid-Open No. 58-131360 discloses that a fuel injection gun for injecting gasoline into a fuel tank is provided with a device that emits a signal according to the octane number of the gasoline, and
, the fuel tank is provided with a receiver that receives such signals, and the octane number of gasoline injected into the fuel tank is detected based on the signal emitted from the fuel injection gun, and the ignition timing is selected accordingly. There are descriptions about.

(Problems to be Solved by the Invention) As mentioned above, high octane number gasoline is said to contain a larger amount of aromatic components than regular gasoline, so the octane number is simply increased compared to regular gasoline. Not only that, but its relative importance is also considered to be large. For this reason,
For example, an electronic circuit control system is configured to control the amount of fuel supplied by a fuel injection valve or a carburetor according to the operating state of the engine in order to appropriately supply the air-fuel mixture to the combustion chamber of the engine. If this is done, if control is applied to high octane gasoline based on the control mode set for regular gasoline, the air-fuel ratio (A/F) of the air-fuel mixture used for combustion in the combustion chamber will change. ,
A problem arises in that the fuel consumption becomes smaller than when regular gasoline is used, that is, it fluctuates to the rich side.

In view of the above, the present invention supplies fuel according to the operating condition of an engine in which multiple types of gasoline with different octane numbers can be used as fuel, and the octane number of the gasoline used as fuel is An engine fuel that can maintain an appropriate air-fuel ratio of the air-fuel mixture provided for combustion in the combustion chamber even when the air-fuel ratio is different, and as a result, the fuel efficiency of the engine can be improved. The purpose is to provide a feeding device.

(Means for Solving the Problems) To achieve the above-mentioned object, the engine fuel supply device according to the present invention, as shown in the basic configuration in FIG. A fuel supply means for supplying gasoline as fuel, an octane number detection sensor for detecting the octane number of the supplied gasoline, and a fuel for controlling the fuel supply means so that the amount of gasoline supplied to the engine corresponds to the operating state of the engine. supply amount control means, the fuel supply amount control means controls the amount of gasoline supplied to the engine when the octane number of gasoline is high compared to when it is low, based on the octane number detection signal obtained from the octane number detection sensor. It is considered to be a small amount.

(Function) In the engine fuel supply device according to the present invention as described above, the fuel supply amount control means detects the engine operating state in response to the engine operating state detection signal, and controls the fuel supply amount based on the detection result. Controlling the supply means to vary the amount of gasoline supplied to the engine according to the operating state of the engine, and in response to an octane number detection signal generated when the octane number detection sensor detects the octane number of gasoline supplied to the engine, When the octane number of the gasoline supplied to the engine is high, the fuel supply means is controlled so as to reduce the amount of gasoline supplied to the engine compared to when the octane number is low. Therefore, even when the octane numbers of the gasolines used are different, the air-fuel ratio of the air-fuel mixture used for combustion is maintained appropriately.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a schematic configuration diagram showing an example of an engine fuel supply system according to the present invention together with the main parts of an engine to which the system is applied.

In FIG. 2, a combustion chamber 14 is formed in an engine body 10 having a cylinder into which a piston 11 is fitted. A fuel injection valve 20 is controlled by the intake air metered by a valve 18 and a control pulse signal cp from a control unit 100 (described later).
A mixture of fuel (gasoline) and an amount of fuel (gasoline) that is injected into the intake passage 16 at a predetermined timing according to the operating state of the engine is supplied via the intake valve 22 .

An air flow meter 24 is interposed in a portion of the intake passage 16 upstream of the throttle valve 18, and the air flow meter 24 generates a detection signal Sa corresponding to the amount of intake air and supplies it to the control unit 100. In addition, the intake passage 16
An intake negative pressure sensor 26 is installed downstream of the throttle valve 18 , and this intake negative pressure sensor 26 generates a detection signal sb corresponding to the intake negative pressure and supplies it to the control unit 100 .

The air-fuel mixture supplied to the combustion chamber 14 is ignited by the spark plug 28 and combusted, and the generated exhaust gas is led out to the exhaust passage 34 via the exhaust valve 32. An 02 sensor 36 that detects the oxygen concentration in the exhaust gas is installed in the exhaust passage 34. This 02 sensor 36 detects, for example, when the air-fuel ratio of the air-fuel mixture subjected to combustion is lower than the stoichiometric air-fuel ratio (on the rich side). ), the level is high and higher than the stoichiometric air-fuel ratio (lean side)
, generates a detection signal So that takes a low level,
It is supplied to the control unit 100.

As described above, fuel is injected from the fuel injection valve 20 to generate an air-fuel mixture and is supplied to the combustion chamber 14 to be combusted from the fuel tank 40 via a fuel supply system that includes a fuel pump, a fuel pressure regulator, etc. The fuel is supplied to the fuel injection valve 20 via a system 41 (indicated by a dashed line in FIG. 1). The fuel tank 40 is provided with a fuel injection port 43 and a cap 45 that is attached to cover the fuel injection port 43. When the cap 45 is opened, the fuel tank 40 is filled with fuel near the fuel injection port 43. When injected, it is turned on and generates a detection signal Sf, which is transmitted to the control unit) 100.
An opening/closing detection switch 47 is provided that sends out signals to the user. When the control unit 100 is supplied with the detection signal sr from the open/close detection switch 47, it stores it in its built-in memory.

A fuel inlet 4 is provided inside the fuel tank 40.
An octane number detection sensor 50 is provided for detecting the octane number of the fuel injected through the fuel tank 3 and determining its type. For example, the octane number detection sensor 50 does not directly detect the octane number of the fuel injected into the fuel tank 40, but indirectly detects the octane number of the fuel by detecting its specific gravity. Ru. In other words, the octane number of a fuel corresponds to the content of aromatic components contained in it, and the higher the proportion of aromatic components, the higher the octane number and the greater the specific gravity of the fuel.
Using this difference in specific gravity, it is determined whether the fuel in the fuel tank 40 is regular gasoline, high octane gasoline, or one with an octane value between these (hereinafter referred to as intermediate gasoline). That's what I do.

In this way, the octane number of the fuel is indirectly detected using the difference in specific gravity, and the type of fuel is determined.
two floats 51 and 52 and an octane number detection switch 5
5 and 56. floats 51 and 5
When the fuel in the fuel tank 40 is regular gasoline, both of the fuel tanks 2 and 2 are in a submerged state, and the octane number detection switches 55 and 56 are both turned off. When the fuel in the fuel tank 40 is intermediate gasoline, only the float 51 floats up and the octane number detection switch 55 is turned on, whereby an octane number detection signal S is obtained from the octane number detection switch 55 and the control is performed. Unit 100 is supplied. Further, when the fuel in the fuel tank 40 is high octane gasoline, the float 52 as well as the float 51 floats, and both the octane number detection switches 55 and 56 are turned on.
and octane number detection signals S, respectively.

and Sz are obtained and supplied to the control unit 100.

The control unit 100 receives the detection signals S a, S b, S o, S f as described above.
, S+, and St, a detection signal S corresponding to the engine rotation speed obtained from a rotation speed sensor 35 shown in a simplified diagram.
The control unit 100 controls the amount of fuel injected from the fuel injection valve 20 according to the engine operation based on these various detection signals. Depending on the state, a control pulse signal Cp is generated to control the air-fuel mixture provided for combustion in the combustion chamber 14 to have a predetermined air-fuel ratio, and is supplied to the fuel injection valve 20. For example, the fuel injection valve 20 receives a control pulse signal c
The intake passage 16 is opened only for a period corresponding to the pulse width of p.
Perform fuel injection to.

In this case, the control unit 100 indicates the operating state of the engine by taking the engine load represented by the intake negative pressure etc. on the vertical axis and the engine speed on the horizontal axis, as shown in FIG. When in the feedback region (F/B region) below the curve Q in the characteristic diagram, the air-fuel ratio of the air-fuel mixture used for combustion is set near the stoichiometric air-fuel ratio based on the detection signal SO from the Ot sensor 36. The air-fuel ratio feedback control is performed to maintain the air-fuel ratio. When such air-fuel ratio feedback control is performed, the fuel tank 40
The air-fuel ratio of the air-fuel mixture provided for combustion is controlled to be focused near the stoichiometric air-fuel ratio, regardless of the octane number of the fuel in the combustion chamber.

However, when the operating state of the engine is outside the feedbank region above the curve Q in the characteristic diagram shown in FIG. 3, for example, if the pulse width of the control pulse signal Cp is set for regular gasoline. ,
When high octane gasoline is used, the air-fuel ratio of the air-fuel mixture used for combustion will fluctuate to the rich side compared to when regular gasoline is used.

Therefore, in this example, when the control unit 100 detects that new fuel has been injected into the fuel tank 40,
When the detection signal Sf from the open/close detection switch 47 is supplied, the type of fuel in the fuel tank 40 is determined based on the octane number detection signals S and S from the octane number detection sensor 50, and the type of fuel is determined to be regular gasoline or intermediate gasoline. The pulse width of the control pulse signal Cp is set so that the air-fuel ratio of the air-fuel mixture provided for combustion is appropriate regardless of whether high-octane gasoline or high-octane gasoline is used.

That is, when neither of the octane number detection signals S1 and S2 is supplied from the octane number detection switches 55 and 56, the control unit 100 determines that regular gasoline is used as the fuel, and changes the pulse width of the control pulse signal Cp. The width tx is set according to the intake air amount and engine speed obtained from the detection signals Sa and Sn, and is supplied to the fuel injection valve 20.
When only the octane number detection signal S1 from the Nochi 55 is supplied, it is determined that intermediate gasoline is used as the fuel, and the pulse width of the control pulse signal Cp is narrower than the width tX when regular gasoline is used. If this is corrected to the width ty and supplied to the fuel injection valve 20, and the octane number detection signals S1 and St are supplied from the octane number detection switches 55 and 56, respectively, it is determined that high octane number gasoline is used. Then, the pulse width of the control pulse signal Cp is corrected to a width tz that is narrower than the width ty when intermediate gasoline is used, and this is supplied to the fuel injection valve 20. As a result, when intermediate gasoline or high octane gasoline is used, the amount of fuel supplied is reduced by a predetermined amount compared to when regular gasoline is used, and as a result, the amount of fuel supplied for combustion is reduced. A proper air-fuel ratio of the air-fuel mixture can be obtained, and the fuel efficiency of the engine can be improved.

As described above, fuel supply control in this example is mainly performed by the operation of a microcomputer built into the control unit 100, but an example of a program executed by such a microcomputer is shown in the flowchart of FIG. I will explain.

The program represented by the flowchart in Figure 4 is as follows:
The ignition switch 37 is turned on to start the engine, and a detection signal St is supplied to the control unit 100 to start. First, in a process 101, detection signals Sa, Sb, So, Sf, S, sz, Sn, etc. is read, and in the subsequent decision 104, it is determined whether the engine operating state is in the feedback region.

This judgment is made based on the detection signal sb from the intake negative pressure sensor 26 and the detection signal Sn from the rotation speed sensor, and the intake negative pressure represented by the detection signals sb and Sn, and therefore the engine load and engine rotation speed, are By checking with the built-in control map corresponding to the characteristic diagram shown in the above-mentioned Figure 3, if the engine operating state is in the feedback region, the air-fuel ratio of the mixture to be used for combustion is determined theoretically. The process proceeds to process 102 to perform air-fuel ratio feedback control to bring the air-fuel ratio to a value close to that of the air-fuel ratio.

In the process 102, the detection signal S from the O2 sensor 36 is
The injection pulse width is set according to the level of o. for example,
When the detection signal So takes a high level, the air-fuel ratio is on the rich side, so the injection pulse width is narrowed, and conversely, the detection signal S
When o takes a low level, the air-fuel ratio is on the lean side, so the injection pulse width is set to widen it, and in the subsequent process 103, control is performed to have a pulse width corresponding to the set injection pulse width. A pulse signal Cp is formed and output to the fuel injection valve 20, and the process returns to process 101.

As a result, the fuel injection valve 20 operates only during a period corresponding to the pulse width of the control pulse signal Cp to perform fuel injection,
The air-fuel ratio used for combustion is focused around the stoichiometric air-fuel ratio.

On the other hand, if it is determined in decision 104 that the engine operating state is not in the feedback region,
Proceeding to decision 105, it is determined whether new fuel has been added. This determination is made by determining whether or not the detection signal Sf is newly supplied from the open/close detection switch 47. If it is determined that fuel has been newly replenished, it is necessary to detect the octane number of the fuel. Assuming that there is, the process proceeds to process 106. In process 106, based on octane number detection signals Sl and St from octane number detection switches 55 and 56 that indirectly detect the octane number using the specific gravity of the fuel, whether the fuel is regular gasoline, intermediate gasoline, or high octane number gasoline is determined. In other words, the octane number of the fuel is detected, and in the subsequent process 107, a correction coefficient for correcting the injection pulse width is set in accordance with the octane number of the fuel detected in the process 106. This correction coefficient is, for example, a positive number, and is k when the fuel is regular gasoline.

(=1), kz (<
k+), and (<kz) if the fuel is high octane gasoline.

Then, in the subsequent process 102, the detection signal Sa from the air flow meter 24 and the detection signal S from the rotation speed sensor 35 are
The basic injection pulse width is calculated based on the intake air amount and engine speed obtained from n, and the correction coefficient set in process 107 for this basic injection pulse width is
, or by , the injection pulse width tx when the fuel is regular gasoline, the injection pulse width ty when the fuel is intermediate gasoline, or the injection pulse width when the fuel is high octane gasoline. Set tz and proceed to process 103.

In process 103, a control pulse signal Cp having a pulse width corresponding to the injection pulse width tx, ty, or tz set in process 102 is formed and output to the fuel injection valve 20, and the process returns to process 101.

In addition, if it is determined in decision 105 that new fuel has not been replenished, the process proceeds to process 107 and sets the same correction coefficient for injection pulse width correction as before. 103 is executed in the same manner as described above and the process returns to process 101.

FIG. 5 is a schematic configuration diagram showing another example of the engine fuel supply system according to the present invention together with a part of the engine to which this is applied.

In FIG. 5, parts corresponding to the respective parts shown in FIG. 2 are shown with the same reference numerals as in FIG. 2, and detailed explanation thereof will be omitted. The example shown in FIG. 5 includes a carburetor 60 installed in the intake system of the engine, and the carburetor 60 includes a float chamber 61 in which the liquid level of fuel is kept constant by a float 62. It is provided.

A main system fuel passage 63 is open at the bottom of the float chamber 61, and the fuel in the float chamber 61 is guided to a main nozzle 67 via a main jet 65 and a main air bleed 66 provided in this main system fuel passage 63. It will be destroyed.

The main nozzle 67 is a small bench eri 68. large bench area 6
9 and a choke valve 71 are arranged therein, the small bench area 68 is opened into the inner wall of the small bench area 68 in order to supply fuel to the intake passage 70 in which the choke valve 71 and the choke valve 71 are disposed. Further, the main air bleed 66 has an open downstream end of an auxiliary air bleed passage 73 that communicates with the atmosphere.

The starting end of the slow system fuel passage 72 is open between the main jet 65 and the main air bleed 66 of the main system fuel passage 63, and the fuel in the float chamber 61 passes through the main system fuel passage 63 to the slow jet 74 and the main air bleed passage 66. Through a slow system fuel passage 72 provided with a slow air bleed 76 and the like, air is also taken in from both a slow boat 77 that opens upstream from the throttle valve 80 and an idle boat 79 whose effective opening area is adjusted by an idle adjustment screw 78. It is supplied to passage 70.

In addition to this configuration, in this example, an air-fuel ratio control solenoid valve 82 that is operated to converge the air-fuel ratio of the air-fuel mixture generated by the carburetor 60 to a target value is located upstream of the auxiliary air bleed passage 73. connected to the end. When the built-in solenoid 82a is excited, the air-fuel ratio control solenoid valve 82 resists the elasticity of the spring means 82b and assumes an open state that communicates the auxiliary air bleed passage 73 with the atmosphere. When not energized, the elasticity of the spring means 82b keeps the auxiliary air bleed passage 73 in a closed state that isolates it from the atmosphere. The amount of air supplied to the main air bleed 66 is adjusted by alternating between the closed state and the closed state.

A control unit 100' that supplies a control pulse signal Cq to an air-fuel ratio control electromagnetic valve 82 is configured to detect an octane number detection sensor 5 disposed inside the fuel tank, similar to the example shown in FIG.
Three AND circuits 91 to which detection signals S and S2 from the zero octane number detection switches 55 and 56 are supplied, respectively.
．． 92 and 93 and these AND circuits 91.92 and 9
The air bleed control circuit 95 is supplied with the output signal Sx, Sy, or Sz from the cap 45 and the detection signal Sf from the opening/closing detection switch 47, which is turned on when the cap 45 is opened. There is.

The air bleed control circuit 95 has three built-in air bleed maps corresponding to the respective octane numbers of regular gasoline, intermediate gasoline, and high octane gasoline.
The air bleed control circuit 95 includes the above-mentioned AND circuit 91.
In addition to the output signals Sx, Sy, and Sz from 92 and 93, detection signals Sn and sb from the rotation speed sensor and the intake negative pressure sensor, respectively, are responsive to the engine speed and intake negative pressure, and therefore the engine load. Supplied.

With this configuration, when the camp is opened and new fuel is injected into the fuel tank, the opening/closing detection switch 47 is activated.
A detection signal Sf is supplied from the air bleed control circuit 95 to the air bleed control circuit 95. At this time, the octane number detection switches 55 and 56
When neither of the octane number detection signals S1 and S2 is obtained from , therefore, when the fuel used is regular gasoline, an output signal Sx having a high level is obtained from the AND circuit 91, and this is used for air bleed control. The signal is supplied to circuit 95. As a result, the air bleed control circuit 95 selects the air bleed map X corresponding to regular gasoline. In addition, the octane number detection switch 55
When only the octane number detection signal S is obtained from
An output signal sy having a high level is obtained from the AND circuit 92 and is supplied to the air bleed control circuit 95.

As a result, the air bleed control circuit 95 selects the air bleed map Y corresponding to intermediate gasoline. Furthermore, when the octane number detection signals S and S8 are obtained from the octane number detection switches 55 and 56, respectively, and therefore, when the fuel used is high octane number gasoline,
An output signal Sz having a high level is obtained from the AND circuit 93 and is supplied to the air bleed control circuit 95.

As a result, the air bleed control circuit 95 selects the air bleed map Z corresponding to high octane gasoline.

After selecting one of the air bleed maps Maps X, Y and Z 1
Based on the detection signals Sn and sb, the control pulse signal Cq has a pulse width depending on the operating state of the engine.
is formed and supplied to the air-fuel ratio control solenoid valve 82.

In this case, the pulse width of the control pulse signal Cq when air bleed map X corresponding to regular gasoline is selected is narrower than that when air bleed map Y corresponding to intermediate gasoline is selected; The pulse width of the control pulse signal Cq when air bleed map Y corresponding to high octane gasoline is selected is narrower than that when air bleed map 2 corresponding to high octane gasoline is selected.

Therefore, when intermediate gasoline is used, the period in which the air-fuel ratio control solenoid valve 82 is kept open is longer than when regular gasoline is used, and the main The amount of air supplied to the air bleed 66 is increased. As a result, the intake passage 70
The amount of fuel supplied to the engine is reduced compared to when regular gasoline is used. Furthermore, when high-octane gasoline is used, the period in which the air-fuel ratio control solenoid valve 82 is kept open is longer than when intermediate gasoline is used, and the main The amount of air supplied to the air bleed 66 is increased. As a result, the amount of fuel supplied to the intake passage 70 is reduced compared to when intermediate gasoline is used. As a result, in this example, as well as in the example shown in FIG. 2, even if the octane numbers of the fuels used are different, an appropriate air-fuel ratio of the mixture for combustion can be obtained, and the fuel Wasteful usage is reduced.

(Effects of the Invention) As is clear from the above explanation, according to the engine fuel supply device according to the present invention, in an engine that can use multiple types of gasoline with different octane numbers as fuel, When the octane number of the gasoline used as fuel is different, the octane number is detected, and the higher the detected octane number, the smaller the amount of fuel supplied to the engine. Since the fuel supply amount is controlled according to the octane number, the air-fuel mixture provided for combustion in the combustion chamber maintains an appropriate air-fuel ratio, and as a result, the fuel efficiency of the engine is improved. can be done.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the basic configuration of the present invention in accordance with the claims, and FIG. 2 is a schematic configuration showing an example of an engine fuel supply device according to the present invention together with the main parts of an engine to which it is applied. 3 is a characteristic diagram used to explain the operation of the example shown in FIG. 2, and FIG. 4 shows an example of an operating program of a microcomputer in an example of a control unit used in the example shown in FIG. Flowchart showing, No. 5
The figure is a schematic configuration diagram showing another example of the engine fuel supply system according to the present invention together with a part of the engine to which it is applied. In the figure, 20 is a fuel injection valve, 40 is a fuel tank, 50 is an octane number detection sensor, 73 is an auxiliary air bleed passage, 8
2 is an air-fuel ratio control solenoid valve, 95 is an air bleed control circuit, and 100 and 100' are control units. Figure 2 4, 1 Figure 3 Engine rotation speed

Claims (1)

[Claims] A fuel supply means for supplying gasoline containing aromatic components to the engine as fuel, an octane number detection sensor for detecting the octane number of the gasoline, and controlling the fuel supply means to control the amount of gasoline supplied to the engine as described above. Based on the octane number detection signal obtained from the octane number detection sensor and based on the octane number detection signal obtained from the octane number detection sensor, when the octane number of the gasoline is high, the gasoline supplied to the engine is 1. A fuel supply device for an engine, comprising a fuel supply amount control means for reducing the amount of fuel supplied.