JPS58222968A - Engine fuel supply system - Google Patents

Abstract

PURPOSE:To make the sufficient atomization of fuel achievable even in case of low fuel pressure as well as to make an optimum air-fuel ratio obtainable in accordance with a state of engine operation, by having a fuel feeder constituted of an air-fuel ratio adjusting mechanism, a control device, a throttle valve provided with a curved surface on its edge part, etc. CONSTITUTION:A solenoid valve that feeds an engine with fuel as opened by a control device is selected from any one among three solenoid valves 15-17. an air-fuel ratio adjusting control signal out of the control device is provided for the selected solenoid valve, and when the solenoid valve selected according to this control signal is set in on or off motion, the flow of fuel to be injected out of an injection nozzle connected to the selected solenoid valve is properly controlled owing to a combined action of a throttle valve 18 fitted with a thick part 19 and a Venturi tube made up at the inner wall of a suction passage. In this way, the engine is driven with a proper air-fuel ratio in accordance with a state of its operation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel supply system for an engine, and more particularly to a fuel supply system for an engine in which the supply of fuel can be electronically controlled.

Generally, when a mixture is supplied to each cylinder of a multi-cylinder engine through a hemanifold, it is necessary to sufficiently atomize the fuel in order to equalize the air-fuel ratio in each cylinder.

Therefore, in conventional engine fuel supply devices, various studies have been made, such as increasing the fuel pressure and injecting the fuel from minute holes, but there is still a problem that atomization of the fuel is insufficient.

Furthermore, increasing the fuel pressure requires an expensive high-pressure fuel pump and also requires safety considerations.

The present invention aims to solve these problems, and provides an engine that is capable of achieving sufficient fuel atomization even at low fuel pressures, and that is also capable of achieving an optimal air-fuel ratio depending on the operating conditions of the engine. The purpose is to provide a fuel supply device for

Therefore, the engine fuel supply device of the present invention includes an engine intake passage in which a throttle valve is interposed, and a fuel supply passage that supplies fuel at a predetermined pressure into the engine intake passage. An air-fuel ratio adjustment mechanism that adjusts the air-fuel ratio by adjusting the amount of fuel flowing through the supply passage, and a control means that outputs an air-fuel ratio adjustment control signal to the air-fuel ratio adjustment mechanism according to the operating state of the engine. A curved surface is formed on the edge of the throttle valve in order to gradually change the flow area of the venturi formed by the edge of the throttle valve and the inner wall of the intake passage as the throttle valve operates. , and the fuel supply passage is open near the narrowest part of the venturi.

Hereinafter, embodiments of the present invention will be explained with reference to the drawings.
Figures 1 to 8 show a fuel supply system for an engine as a first embodiment. Figure 1 is its overall configuration, Figure 2 is its block diagram, and Figure 3 is the details of its fuel supply section. Fig. 4 is an output characteristic diagram to explain its action, Fig. 5 is a graph showing an example of engine speed fluctuation, Fig. 6 is a fuel consumption-air fuel ratio characteristic diagram, and Fig. 7 is a graph showing an example of the engine speed fluctuation. A graph for explaining the operation of the fuel supply section, and FIG. 8 is a block diagram including other control means.

As shown in FIGS. 1 and 2, a rotation speed detection section (rotation speed sensor) 1 for detecting the rotation speed N of the engine E is provided.

Further, a throttle opening degree detection section (throttle opening degree sensor) 2 is provided as a load detection section, so that the load state of the engine E can be detected based on the opening degree θ of the throttle valve 18.

Further, an oxygen concentration detection section (02 sensor) 4 is provided which detects the oxygen concentration in the exhaust gas in the exhaust passage 3 of the engine E and detects air-fuel ratio information.
(r) A temperature detection unit (temperature sensor) 5 is provided for detecting temperature (for example, cooling 1, water temperature Tw, and lubricating oil temperature).

Also, a rotational fluctuation detection unit (ΔN sensor) that receives a signal from the rotational speed sensor 1 and detects a rotational fluctuation ΔN of the engine E.
6 is provided.

Further, an acceleration detection section (acceleration sensor) 7 is provided which receives a signal from the throttle opening sensor 2 and detects acceleration dθ/di (including deceleration). It is configured as a differentiation circuit that differentiates and outputs the signal from 2.

By the way, as shown in FIG. 3, the intake passage 8 of the engine E
A thick wall portion 19 is provided on the downstream left half surface of the throttle valve 18 installed in the throttle valve 18 so as to form a curved surface at the edge of the throttle valve 18. A venturi is formed with the inner wall of the intake passage 8, so that even if the opening degree of the throttle valve 18 changes, the flow area within the intake passage 8 does not change abruptly but changes gradually. ing.

Fuel injection ports 10 to 14 of the fuel supply section 9 are distributed and opened in the inner wall of the intake passage 8 adjacent to the narrowest portion of the formed venturi. As shown in FIG. 3, each fuel injection port 10 to 14 is provided with a solenoid valve (electromagnetic valve) 15 as a metering valve that constitutes an air-fuel ratio adjustment mechanism.
17 and the orifice, fuel is supplied from the fuel supply passage 22. These solenoid valves 15 to 17 are
The fuel supplied from the fuel supply passage 22 is controlled by duty control and is supplied to each of the fuel injection ports 10 to 14.

Note that three solenoid valves 1 disposed in the fuel supply section 9
5 to 17 each perform a different operation. That is,
Fuel injection into the intake passage 8 can be performed most efficiently at the narrowest part of the venturi formed by the thick part 19 of the throttle valve 18 and the inner wall of the intake passage 8. It changes depending on the opening degree of the valve 18. Therefore, so that fuel can be injected from the injection port closest to the narrowest part of the fuel injection ports 10 to 14, the solenoid valve connected to that injection port is opened to supply fuel, and the other two injection ports are Keep the solenoid valve closed.

Note that there is a thick wall portion 2 on the upstream right half of the throttle valve 18.
0 is set and 1. This thick portion 20 is provided to prevent the flow area of the intake passage 8 on the right side of the throttle valve 18 from becoming excessive even if the opening degree of the throttle valve 18 becomes narrow. May be omitted. Further, reference numeral 21 indicates a throttle axis.

Furthermore, the solenoid valves 15 to 15 in the fuel supply passage 22
A fuel pressure regulator 24 that operates according to the pressure (negative pressure) in the intake passage 8 acting through the passage 27 is disposed in a portion closer to the fuel tank 23 than the part where the fuel pressure regulator 17 is disposed. (fuel pressure) can be adjusted to an appropriate value (a value higher than atmospheric pressure).

Note that the reference numeral 26 in FIG. 3 indicates a return passage for returning fuel to the fuel tank 23, and P indicates a fuel pump.

With this configuration, sufficient fuel atomization can be achieved with low fuel pressure regardless of the opening degree of the throttle valve 18.

By the way, as shown in Figures 1 and 2, each sensor 1.2
．． A control means 28 that outputs an air-fuel ratio adjustment control signal according to the operating state of the engine E based on the signals from 4 to 7.
is provided.

This control means 28, as shown in FIG.
．． Interface 35 for solenoid valves 15-17.
First to third read memories
) as the first to third ROMs 36 to 38, the first to third ROMs 36 to 38 as
Third read/write memory (Read/Wri)
1st to 3rd RAM 39 as memory)
41 and a CPU 42 as a processor section.

In addition, each interface 29 to 35 and each ROM 36 to
38 and each RAM 39 to 41 are CPU; 42 and I1
0 bus 43.

The input interfaces 29 to 34 differ depending on the type of sensor, but if the sensor is an analog signal detection type, the interface used is a combination of an A/D converter and a serial/parallel converter. If the sensor is of a digital signal detection type, a serial/parallel converter or the like is used as an interface.

In addition, the output interface 35 supplies a serial pulse train signal to the duty control type solenoid valves 15 to 17, so the interface 35 is a parallel/serial converter that converts parallel data from the bus 43 into a serial signal. etc. are used.

The ilROM 36 contains a value corresponding to the fuel flow rate according to the engine speed N and the throttle opening θ as the engine load state [this value is actually the valve opening time TB (ms) of one duty control as shown in the following table. ) has been converted to ] is a read-only memory that stores data in a matrix-type map, and the data TB stored in this first ROM 36 will be the basis for subsequent fuel control, so this data TIl is called base data or base map.

The second ROM 37 is a read-only memory that stores a correction coefficient value K (dθ/dt) corresponding to the acceleration (dθ/dt), and the third ROM 38 stores a correction coefficient value K (dθ/dt) corresponding to the engine temperature (cooling water temperature) Tw. This is a read-only memory that stores K(Tw).

- The first RAM 39 is a preset operating area such as a low speed and low load operating area as shown by symbol A in FIG.
It is a readable and writable memory that can store correction coefficient values KA (θ, N) for correcting the signal from the first ROM 36 in a matrix-type map so that the fuel flow rate becomes the stoichiometric air-fuel ratio.

The second RAM 40 stores correction coefficient values KA to be stored in the first RAM 39 in other operating ranges different from the operating range A, such as high-speed operating ranges and high-output operating ranges as shown by symbols B and C in FIG. (θ.

N), the fuel flow rate is greater than the stoichiometric air-fuel ratio [
Correction coefficient value KC (θ+N) for correcting the signal from the first ROM 36 so that the signal is in a lean mixture (lean) state] or smaller [in a rich mixture (rich state)]
It is a readable and writable memory that stores information in a matrix-type map.

Generally, in a multi-cylinder engine E, the explosion timing differs for each cylinder, so the engine speed N constantly fluctuates as shown in Figure 5. Then, a misfire occurs in the cylinder, and as shown by the symbol, large irregularities in the rotational speed N (specifically, a significant decrease in the rotational speed N) occur due to this misfire. When a misfire occurs in this way, the fuel consumption deteriorates conversely as shown by the symbol F in FIG. 6.

Therefore, the mixture should be made lean to the extent that misfire does not occur, but the correction coefficient value K11 (θ, N) for this purpose is the third
It is stored in the RAM 41 in a matrix-type map.

Specifically, this corresponds to the number of times that a misfire occurs within a predetermined period of time (this corresponds to the number of times that the rotational fluctuation ΔN exceeds a predetermined value ΔN+ (this value is allowed to have a predetermined width). ] Calculate and determine the correction coefficient value KB (θ, N) that gives a certain value n (this value is also allowed to have a predetermined width), or
degree of misfire (this is the degree of misfire when the rotational fluctuation ΔN exceeds a predetermined value ΔN)
′”h f 51.s ′″′″111・ )”゛66
The correction coefficient KB (θ, N) is calculated and determined as follows.

The CPU 42 controls the timing of taking out the signals from each sensor 1, 2, 4 to 6 via the interfaces 29 to 34 and the 10 bus 43, and
36 to 38 via the i10 bus 43, data writing and data reading to the first to third RAMs 39 to 41 are controlled via the I10 bus 43, and control to the solenoid valves 15 to 17. Control the signal output via ■10 bus 43 and interface 35,
Based on the signals from each sensor 1, 2.4 to 6, the ROM36
38 and RAMs 39 to 41 and perform appropriate arithmetic processing.

Next, a specific example of air-fuel ratio control by this control means 28 will be explained.

In response to the signals from the rotational speed sensor 1 and the throttle opening sensor 2, base data T is read out from the corresponding address in the first ROM 36, and from this data T, C is read out.
The PU 42 determines what operating range the engine E is currently in (specifically, which of the operating ranges A, B, and C in FIG. 4 is the operating range).

Then, the CPU 42 uses the ROMs 36 to 38 and the RAM 3 to obtain an appropriate air-fuel ratio according to the operating ranges A to C.
Read data from 9-41 and solenoid valves 15-17
The output (air-fuel ratio adjustment control signal) TO is easily calculated.

Here, in operating region A (low speed, low load operating region), it is desirable to operate at a stoichiometric air-fuel ratio mainly from the viewpoint of exhaust gas purification, and in operating region B (high speed operating region), it is desirable to operate at a stoichiometric air-fuel ratio, mainly from the viewpoint of reducing fuel consumption. It is desirable to operate with a lean air-fuel mixture with an air-fuel ratio of about 18, and in operating region C (high-output operating region), the air-fuel ratio should be about 11 to 13, mainly from the viewpoint of improving output and preventing burnout of spark plugs, etc. It is desirable to operate with a rich mixture.

Therefore, in this example, the CPU 42 operates in the operating range A-C.
The following output TD is calculated accordingly.

First, in operating region A, TD = T++ ” KA (θ, N) φK (T, )・
The calculation K(dθ/d t ) number Φ ・(1) is performed, and in the operating region B, To ``” TB
”K11(θ, N)・K(Tw)・K(dθ/d t
)...e(2) is performed, and in operating region C, To ""TB
” Kc(θ, N) −K(TW) −K(dθ/d
t)...-(3) is performed.

In the above equation, T□ is the data in the first ROM36, and K
(dθ/dt) is the data in the second ROM 37, K ('
rw) is data in the third ROM 38, and KA(θ,
N) is data in the first RAM 39, Kc (θ, N) is data in the second RAM 40, KB (θ, N) is data in the third RAM
This is the data in 41.

Note that T, , K (dθ/dt) and K (Tw) are fixed data written in advance in the ROM, but K
A (θ, N), KB (θ, N), KC (θ, N)
For example, the data is calculated by the CPU 42 to an appropriate value according to the operating state and then written to each RAM. Therefore K.A.
(θ, N), Kl (θ, N), and KC (θ+N) are rewritten at predetermined intervals according to the operating state.

In addition, in Fig. 4, the characteristic indicated by the symbol θ is the output characteristic when the throttle opening is θ, and the symbol NA indicates the appropriate engine speed representing the boundary between the low speed range and the high speed range. There is.

In this way, the appropriate output TD can be set according to each operating region A to C.
The solenoid valves 15 to 17 are used as air-fuel ratio adjustment control signals.
However, in the acceleration operation state (including deceleration operation) and constant speed operation state, the above formula +1j ~ (3
), the output TD should be different, but
The cases of such an accelerated driving state and a constant speed driving state will be explained.

First, in the case of accelerated driving, the driving conditions change rapidly, so it is necessary to read and process data from memory with extremely high responsiveness. The value is fixed to 1 (for example, 1) and arithmetic processing is quickly performed.

That is, the fixed data TB according to the output is stored in the first ROM3.
At the same time, the fixed data K (dθ/d t ) corresponding to the acceleration is quickly read from the second ROM 37, and is immediately subjected to signal processing and outputted as the output TD.

The kneading is the same in all operating ranges A-C. At this time, temperature data K(Tw) from the third ROM 38 is also used, but other data KA(θ, N)Kll(θ, N
) l KC (θ, N) is fixed to an appropriate value as described above.

As a result, even in such an accelerated driving state, fine-grained and responsive fuel control, that is, air-fuel ratio control, can be performed.

In the case of constant speed operation, there are almost no changes in the operating state, or even if there are, the changes are gradual, so the writing and reading of data to and from the memory (RAM) that can be written to and read from is performed appropriately. . In addition, in the case of ideal constant speed operation, there is a possibility that the acceleration becomes zero and the output TD becomes zero, so in such a case, set an appropriate value (for example, 1
) in the second ROM 37 so that the correction coefficient value K (d
θ/dt) is set.

By the way, the lRO is adjusted so that the fuel flow rate becomes the stoichiometric air-fuel ratio.
Correction coefficient value K A for correcting the signal from M36
Calculation of (θ, N) can be done in a very short time because it can be fixed values (of course, these values vary depending on the output, so the data becomes a matrix). Even though you can read and write it in no time.

On the other hand, calculating the correction coefficient Kc (θ, N) for correcting the signal from the first ROM 36 so as to obtain another air-fuel ratio takes more time than the above calculation.

Therefore, for example, in operating region C, 4
~5 rotations is based on the signal from the 02 sensor 4.
Using the correction coefficient value KA (θ, N) (this value can be obtained instantaneously) to be stored in M39, correct the signal TB from the first ROM 36 to the stoichiometric air-fuel ratio of 5,
During these 4 to 5 rotations, the signal T from the 1st ROM 36 is sent so that the air-fuel ratio becomes appropriate (in this case, 11 to 13 to achieve a rich state) based on the correction coefficient KA (θ, N).
, the CPU calculates the correction coefficient value Kc (θ, N) for correcting
42, the correction coefficient value K obtained in this way
After writing C(θ, N) to the second RAM 40, the remaining 15 to 16 rotations are based on the signal from the same < 02 sensor 4 and using the above correction coefficient value Kc(0, N). The signal T from the first ROM 36 is corrected so that the mixture becomes a mixture.

Similarly, for operating region B, the operation is performed at the stoichiometric air-fuel ratio for several times (for example, 4 to 5 rotations) out of a predetermined number of rotations (for example, 20 rotations), and for the remaining number of rotations (for example, 15 to 1 rotation).
6 rotations) are operated with a lean mixture.

In addition, in the constant speed driving state in driving region B, it is preferable to operate with a mixture as lean as possible without causing a misfire in order to improve fuel efficiency.
The correction coefficient value KB (θ, N) that achieves the optimal lean mixture as described above is determined by the CPU
42, and the correction coefficient value KB (θ, N) thus obtained is written into the third RAM 41, and then read out from the third RAM 41 and used for calculating the output TD. .

In this case, the correction coefficient value KB is adjusted so that the air-fuel ratio is gradually increased until the number of misfires occurs reaches a predetermined value n.
(θ, N) is updated in the third RAM 41, and is updated with a correction coefficient value KB(θ, N)-i: such that the number of misfires eventually reaches a predetermined value n.

Furthermore, the output TD is also corrected according to the engine temperature Tw, and the correction coefficient value in this case is -(T
, ), for example, if the cooling water temperature is below ]O0C, K(
TwL), K (TwM) for lO to 50°G, and K (TwII) for 50°C or higher, and are stored in the third ROM 38. The correction coefficient value K(Tw) is set such that the lower the engine temperature, the richer the mixture becomes.

This allows for appropriate control depending on the engine operating condition.
1-The processed output To is determined.

In particular, the CPU determines which solenoid valve to open among the 15 to 170 solenoid valves based on the throttle valve 180 opening degree θ.
42, but the selection method is, for example, the 7th
From the relationship between the intake air flow rate and the fuel amount corresponding to the opening degree θ of the throttle valve 180 as shown in the figure, the solenoid valve 15 is activated in the area a, the solenoid valve 16 is activated in the area b, and the solenoid valve 16 is activated in the area C. A respective selection of the solenoid valves 17 is performed.

In this way, the output TD, which has been appropriately processed according to the engine operating state, is sent via the I10 bus 43 and the interface 35 to the throttle valve opening as a control signal for adjusting the air-fuel ratio in the form of pulse width modulation, etc. It is supplied to the selected solenoid valve accordingly.

The solenoid valve selected in this manner is subjected to duty control according to the output TI to turn on and off the fuel supply passage 22, so that the flow rate of fuel supplied from the fuel injection port communicating with the selected solenoid valve is controlled. , Thick wall portion 19-handed throttle valve 18 and intake passage inner wall (throttle bore)
Coupled with the action of the venturi formed by the engine 1, the engine 1 is appropriately controlled, and thereby the engine E is operated at an appropriate air-fuel ratio depending on its operating state.

Note that the reference numeral 44 in FIG. 1 indicates an air cleaner.

Further, the control means 28' may be constructed as shown in FIG. That is, what is shown in FIG. 8 is the first to third R.
The OM36-38 receives the signal from the sensor 1゜2.5.7, and operates the first to third ROM36-38 in response to the signals from the sensors
Fixed data TB, K at the corresponding address within 38
(dθ/di).

K(Tw) is output, and other functions are almost the same as those of the previous embodiment.

Note that in FIG. 8, the same reference numerals as in FIG. 2 indicate substantially the same parts.

Furthermore, the correction coefficient value kA(θ,
N), KB(θ, N), and Kc(θ, N) in the RAM, the correction coefficient values KA(θ), KB(of, KC(/7 );KA
(N), KII(N), and KC(N) may be stored in RAM, and , KR, and Kc may be stored in RAM as correction coefficient values as constants that are determined independently of θ and N. good.

FIG. 9 is an explanatory diagram showing details of main parts of an engine fuel supply device as a second embodiment of the present invention, and in FIG.
The same reference numerals as in Figures 8 to 8 indicate almost the same parts.

In this second embodiment, as shown in FIG. 9, bleed air supply mechanisms 48 to 50 are disposed immediately before the fuel injection ports 45 to 47 of the fuel supply passage 22 in the fuel supply section 9.

These bleed air supply mechanisms 48 to 50 take in bleed air from orifice-shaped bleed air intakes 51 to 53 and blow out the bleed air from bleed air injection ports 54 to 56 that open just before the fuel injection ports 45 to 47. Then, the atomized fuel is injected into the intake passage 8 from the fuel injection ports 45 to 47.

By atomizing the fuel in advance using bleed air in this manner, the effect of fuel atomization at low fuel pressure is further promoted.

In addition, also in the case of this second embodiment, the control means 28;
The solenoid valve to be opened by 8' to supply fuel is selected from among the three solenoid valves 15 to 17. This selected solenoid valve is also connected to control means 28;
An air-fuel ratio adjustment control signal is supplied from 8', and the selected solenoid valve is turned on and off according to this control signal, thereby increasing the flow rate of fuel injected from the fuel injection port connected to the selected solenoid valve. , combined with the action of the venturi formed by the throttle valve 18 with the thick wall portion 19 and the inner wall of the intake passage (throttle bore), is appropriately controlled.
As a result, as in the first embodiment described above, the engine E is operated at an appropriate air-fuel ratio depending on its operating state.

Note that the number of fuel injection ports communicating with each solenoid valve may be one or more. When a plurality of fuel injection ports are provided for one valve, the fuel injection ports are distributed so as to be close to the narrowest part of the venturi, which changes with the operation of the throttle valve 18.

Furthermore, instead of providing the thick wall portion 19 so that a curved surface is formed at the edge of the throttle valve 18, the edge of the throttle valve 18 is bent so that a curved surface is formed at the bent edge. Good too.

As described above in detail, the engine fuel supply device of the present invention includes an engine intake passage in which a throttle valve is interposed, and a fuel supply passage that supplies fuel having a predetermined pressure into the engine intake passage. an air-fuel ratio adjustment mechanism that adjusts the air-fuel ratio by adjusting the amount of fuel flowing through the fuel supply passage; and an air-fuel ratio adjustment mechanism that outputs a control signal for air-fuel ratio adjustment according to the operating state of the engine to the air-fuel ratio adjustment mechanism. control means is provided to control the edge of the throttle valve so as to gradually change the flow area of the venturi formed by the edge of the throttle valve and the inner wall of the intake passage as the throttle valve is actuated; With a simple configuration in which a curved surface is formed on the venturi and the fuel supply passage opens near the narrowest part of the venturi, it has the advantage of sufficient fuel atomization even at low fuel pressure, and the engine This has the advantage of being able to achieve the optimum air-fuel ratio depending on the operating conditions of the vehicle.

[Brief explanation of drawings]

1 to 8 show a fuel supply device for an engine as a first embodiment of the present invention, in which FIG. 1 is an overall configuration diagram thereof, FIG. 2 is a block diagram thereof, and FIG. 3 is a fuel supply unit thereof. FIG. 4 is an output characteristic diagram to explain its action, FIG. 5 is a graph showing an example of engine rotation fluctuation, FIG. 6 is a fuel consumption-air fuel ratio characteristic diagram, and FIG. The figure is a graph for explaining the operation of the fuel supply section, FIG. 8 is a block diagram including other control means, and FIG. 9 is a diagram of a fuel supply system for an engine as a second embodiment of the present invention. FIG. 3 is an explanatory diagram showing details of main parts. 1. Rotation speed sensor, 2. Throttle opening sensor as load detection section, 3. Exhaust passage, 4. 02 sensor as oxygen concentration detection section, 5. Temperature sensor, 6. Rotation fluctuation detection ΔN sensor, 7-unit acceleration sensor,
8e. Intake passage, 9. Fuel supply section, 10 to 14. Fuel injection port, 15 to 17. Renoid valve constituting the air-fuel ratio adjustment mechanism, 18. Throttle valve, 19. Flesh with curved surface. Thick part, 20... Thick part, 21... Throttle shaft, 22... Fuel supply passage, 23... Fuel tank, 24...
・Fuel pressure regulator, 26...Return passage, 27...
Passage, 28.28'... Control means, 29-35... Interface, 36-38... First to third ROMs as first to third read memories, 39-41... First to third.
1st to 3rd RA as third read/write memory
M142...CI"U as a piff processor section, 43
・-I10 bus, 44・Φ air cleaner, 45-47 fist・fuel injection port, 48-50・・bleed air supply mechanism,
51-53...Bleed air intake, 54-56...Bleed air outlet, E...Engine, P...Fuel pump. Figure 1 Figure 3 Figure 4 Figure 5 Figure 6 Figure 421- Figure 7 Intake air flow rate-

Claims (1)

[Claims] The engine intake passage has a throttle valve interposed therein, and a fuel supply passage that supplies fuel at a predetermined pressure into the engine intake passage, and adjusts the amount of fuel flowing through the fuel supply passage to adjust the air-fuel ratio. an air-fuel ratio adjustment mechanism that adjusts the air-fuel ratio adjustment mechanism; and a control means that outputs an air-fuel ratio adjustment control signal to the air-fuel ratio adjustment mechanism according to the operating state of the engine. In order to gradually change the flow area of the venturi formed by the edge of the throttle valve and the inner wall of the intake passage, a curved surface is formed at the edge of the throttle valve, and the fuel supply passage is formed at the narrowest point of the venturi. 1. A fuel supply device for an engine, characterized in that it has an opening near the section.