JPH08246918A - Fuel injection type engine - Google Patents

Abstract

PURPOSE: To improve output and fuel consumption by controlling a fuel injection quantity by accurately detecting an air sucking quantity, and realizing the optimal air-fuel ratio. CONSTITUTION: In a fuel injection type engine 1 formed to inject a proper quantity of fuel into an upstream intake air passage 27 of an intake valve device 26 by finding a basic air quantity on the basis of opening of a throttle 28 and rotating speed of the engine 1, an intake air pressure detecting means 41 is arranged in the upstream of the intake valve device 26, and a fuel injection quantity is corrected on the basis of detected intake air pressure.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a fuel injection engine.

[0002]

2. Description of the Related Art A carburetor is used as a means for supplying an air-fuel mixture to an engine. The carburetor is located in the middle of the intake passage of the engine, and uses the flow of air that the engine inhales to suck the fuel out of the room inside the carburetor.
It is atomized and mixed with air and sent to the engine as a mixture of fuel and air.

The carburetor is trying to obtain the best setting by combining a number of jets in order to meet the characteristics of the engine and the running requirements. However, the carburetor flexibly adapts to changes in operating conditions and the surrounding environment. It was impossible to do.

Therefore, in recent years, an increasing number of engines have a fuel injection device instead of the carburetor. The fuel injection device has throttle opening, engine speed, engine temperature,
It detects outside air temperature and atmospheric pressure with a sensor, processes the information with a computer to obtain a correction value, and at that time the most appropriate required fuel amount is directly injected into the intake passage of the engine with a fuel injector, and the combustion efficiency is While the output can be improved well, there is an advantage that the fuel consumption is small because only the minimum required amount of fuel is injected.

By the way, since the exhaust outlet of a general engine is open to the atmosphere, the amount of air taken into the engine is uniquely calculated from the throttle opening and the engine speed.

[0006]

However, in the case of an outboard motor used for a motor boat or the like, since the exhaust outlet of the engine is underwater, the exhaust passage may be changed depending on the running condition of the hull, such as speed and forward / backward movement. Back pressure may change. In particular, in the case of an outboard motor equipped with a two-cycle engine, a change in back pressure changes the intake amount of air (intake amount). As a result, even if the intake air amount is obtained from the throttle opening and the engine speed as in the conventional fuel injection device, it may differ from the actual intake air amount, resulting in lower engine output, deterioration of fuel consumption, deterioration of exhaust gas, etc. There is a risk of problems.

Also, in the case of a multi-cylinder engine, the exhaust passage length of a general engine is configured to be substantially equal, but in the case of an outboard motor, the exhaust passage length of the engine may differ for each cylinder due to its structure. is there. Since the exhaust passage length of the engine is different for each cylinder, the back pressure of each exhaust passage is also different, and the intake amount of each cylinder varies. As a result, the conventional method of obtaining the intake air amount from the throttle opening and engine speed, the method of directly obtaining the intake air amount by using the hot wire system or the Karman vortex, the intake air pressure from the intake path pressure and the engine speed The optimum air-fuel ratio cannot be achieved even if the same amount of fuel is injected into each cylinder based on the calculated value by the method of calculating the amount, the method of calculating the intake amount from the pressure in the crankcase of one of the multiple cylinders, etc. However, problems such as a decrease in engine output, deterioration of fuel consumption, deterioration of exhaust gas, and the like may occur.

In order to solve the above-mentioned problem, there is a method of detecting the exhaust pressure and correcting the fuel injection amount as shown in, for example, Japanese Unexamined Patent Publication No. 5-18287, but for example, the temperature near the exhaust port is high. -Because of the high pressure, the exhaust pressure detecting means needs to have pressure resistance and temperature resistance, resulting in cost increase and the reliability of the exhaust pressure detecting means is poor. Further, since the cooling water passage and the scavenging port are arranged around the exhaust port, it is difficult to install the exhaust pressure detecting means. Furthermore, when the exhaust pressure detecting means is installed away from the exhaust port, moisture and salt may be attached, and the reliability of the exhaust pressure detecting means is also poor.

On the other hand, as disclosed in, for example, Japanese Patent Laid-Open No. 5-10168, there is a method of detecting the pressure in the crankcase and correcting the fuel injection amount. The compression stroke considerably increases the pressure, and as described above, the intake pressure also becomes unstable due to the change in the intake air amount due to the change in the back pressure.

The present invention has been made in consideration of the above-mentioned circumstances, and improves output and fuel efficiency by accurately detecting the intake amount of air and controlling the fuel injection amount to realize the optimum air-fuel ratio. It is an object of the present invention to provide a fuel injection type engine aiming at the above.

[0011]

In order to solve the above-mentioned problems, a fuel injection engine according to the present invention is provided with:
A fuel injection engine in which the basic air amount is obtained based on the throttle opening and the engine speed, and an appropriate amount of fuel is injected into the upstream intake passage of the intake valve device, as described in 1. In the above, an intake pressure detecting means is provided on the upstream side of the intake valve device, and the injection amount of the fuel is corrected based on the detected intake pressure.

In order to solve the above-mentioned problems, as described in claim 2, the basic air amount is obtained based on the throttle opening and the engine speed, and the upstream intake passage of the intake valve device is obtained. In a fuel injection engine having a plurality of cylinders adapted to inject an appropriate amount of fuel therein, an intake pressure detecting means is provided immediately before the intake valve device of each cylinder, and the intake pressure of each detected cylinder is detected. The fuel injection amount to each cylinder is corrected based on the atmospheric pressure.

Further, in order to solve the above-mentioned problems,
As described in claim 3, the basic air amount is obtained based on the opening degree of the throttle and the engine speed, and an appropriate amount of fuel is injected into the upstream intake passage of the intake valve device. In a fuel injection engine having a cylinder of
Intake pressure detection holes are provided in front of the intake valve device of each cylinder, respectively, and these detection holes are connected to intake pressure detection means of a number equal to or less than the number of cylinders through an intake pressure detection passage.
The intake pressure detection means is provided with a switching valve in the middle of the intake pressure detection passage to selectively detect the intake pressure of each cylinder, and based on the detected intake pressure of each cylinder, It is configured to correct the fuel injection amount.

Further, in order to solve the above-mentioned problems, as described in claim 4, the basic air amount is obtained based on the opening degree of the throttle and the rotation speed of the engine, and the intake air on the upstream side of the intake valve device is obtained. In a fuel injection engine that has a plurality of cylinders and has different exhaust passage lengths extending from the respective cylinders, it is possible to inject an appropriate amount of fuel into the passages by performing experiments or the like in advance. The intake amount of each cylinder is calculated for each engine speed, and the fuel injection amount to each cylinder is corrected based on the intake amount.

In order to solve the above-mentioned problems,
As described in claim 5, the basic air amount is obtained based on the throttle opening and the engine speed, and an appropriate amount of fuel is injected into the upstream intake passage of the intake valve device. In a fuel injection type engine having a shift mechanism, in which a driven body driven by the engine can be rotated normally and reversely by the shift mechanism, an intake for each engine speed depending on a shift position of the shift mechanism has been previously conducted by an experiment or the like. The fuel injection amount is corrected based on the intake air amount.

[0016]

In the present invention having the above-mentioned structure, the basic air amount is obtained based on the opening degree of the throttle and the rotational speed of the engine, and an appropriate amount of fuel is injected into the upstream intake passage of the intake valve device. Since the intake pressure detecting means is provided on the upstream side of the intake valve device of the fuel injection engine, the injection amount of the fuel is corrected based on the detected intake pressure. Even if the back pressure in the exhaust passage changes the intake air amount, it is possible to control the fuel injection amount so that an optimum air-fuel ratio can be obtained by the relatively stable intake pressure, so that the engine output and the fuel consumption can be improved.

Further, it has a plurality of cylinders adapted to obtain a basic air amount on the basis of the throttle opening degree and the engine speed and inject an appropriate amount of fuel into the upstream intake passage of the intake valve device. An intake pressure detecting means is provided in front of each intake valve device of each cylinder of the fuel injection engine, and the fuel injection amount to each cylinder is corrected based on the detected intake pressure of each cylinder. Even if the intake air amount of each cylinder varies, the fuel injection amount can be controlled for each cylinder so that the optimum air-fuel ratio can be obtained, and the engine output and the fuel consumption can be improved.

Further, a basic air amount is obtained based on the opening degree of the throttle and the engine speed and a plurality of cylinders are arranged to inject an appropriate amount of fuel into the upstream intake passage of the intake valve device. An intake pressure detection hole is provided in front of each intake valve device of each cylinder of the fuel injection engine, and these detection holes are connected to intake pressure detection means of a number equal to or less than the number of cylinders through an intake pressure detection passage. The intake pressure detecting means is provided with a switching valve in the middle of the intake pressure detecting passage to selectively detect the intake pressure of each of the cylinders, and the intake pressure of each cylinder is detected based on the detected intake pressure of each of the cylinders. Since the fuel injection amount is corrected, the fuel injection amount can be controlled for each cylinder so that the optimum air-fuel ratio can be obtained even if the intake air amount of each cylinder varies. When there are many Intake pressure detection can be reduced tolerance means, can be improved and improvement fuel consumption of the engine output.

Furthermore, the basic air amount is calculated based on the throttle opening and the engine speed, and an appropriate amount of fuel is injected into the upstream intake passage of the intake valve device, and a plurality of The intake amount of each cylinder for each engine speed is obtained in advance by an experiment or the like of a fuel injection engine having cylinders and the lengths of the exhaust passages extending from the respective cylinders, and based on the intake amount Since it is configured to correct the fuel injection amount to each of the cylinders, even if the back pressure of each exhaust passage is different and the intake air amount of each cylinder varies, an optimum air-fuel ratio can be obtained. The fuel injection amount can be controlled for each cylinder, and the engine output and the fuel consumption can be improved.

Then, the basic air amount is obtained based on the throttle opening and the engine speed, and an appropriate amount of fuel is injected into the upstream intake passage of the intake valve device, and the shift mechanism is provided. Having a driven body driven by the engine, the intake amount for each engine speed depending on the shift position of the shift mechanism is obtained in advance by a test or the like of a fuel injection type engine in which the driven mechanism can be rotated normally and reversely by the shift mechanism,
Since the fuel injection amount is corrected based on this intake air amount, even if the intake air amount changes depending on the shift position, the fuel injection amount can be controlled so that the optimum air-fuel ratio can be obtained, and the engine output It is possible to improve the fuel efficiency, the fuel efficiency, and the fuel efficiency.

[0021]

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

FIG. 1 is a longitudinal sectional view showing an example of an outboard motor 2 having a fuel injection engine 1 to which the present invention is applied. The outboard motor 2 is mounted on a transom 4 of a hull 3 with a bracket 5 interposed therebetween. Be installed. The outboard motor 2 has a drive shaft housing 6, an engine holder 7 is provided on the drive shaft housing 6, and the engine 1 is installed on the engine holder 7. This engine 1
Is configured by combining the cylinder head 8, the cylinder block 9, the crankcase 10, and the like. The engine 1 installed on the engine holder 7 is covered with an engine cover 11. The engine 1 is, for example, a water-cooled 2-cycle 4-cylinder engine, and has a crankcase 1
The crankshaft 12, which is rotatably supported within 0, is arranged substantially vertically.

On the other hand, a gear case 13 is provided below the drive shaft housing 6, and a propeller shaft 14 which is a driven body driven by the engine 1 is rotatably supported by the gear case 13. The drive shaft 15 connected to the crankshaft 12 transmits the rotation of the engine 1 to the propeller shaft 14, and drives the propeller 16 supported at the rear end of the propeller shaft 14. A shift mechanism 17 is provided near the front end of the propeller shaft 14 so that the propeller shaft 14 can be rotated forward and backward by remote control. The shift mechanism 17 is provided with a shift position sensor (not shown) that detects the shift position (forward / neutral / reverse).

A cylinder 18 is formed in the cylinder block 9 of the engine 1. It should be noted that the cylinder 18 is arranged first in the upper part of the drawing for the sake of convenience.
The cylinder 18a will be referred to as a second cylinder 18b, a third cylinder 18c, and a fourth cylinder 18d. A piston 19 is slidably inserted into each of the cylinders 18a, and the crank pin 20 of the crank shaft 12 is connected by a connecting rod 21. The reciprocating stroke of the piston 19 is converted into the rotational movement of the crankshaft 12.

An engine 22 is provided at the upper end of the crankshaft 12, and the rotation speed of the engine 1 (crank angle of the crankshaft 12) is output by detecting the rotation of the magnet 22 on the side of the magnet 22. A rotation speed sensor 23 is provided. Also, Engine 1
An engine temperature sensor (not shown) that detects the temperature of the engine and a cooling water temperature sensor (not shown) that detects the temperature of the engine cooling water are also provided in the. Reference numeral 24 is a combustion chamber, and a spark plug 25 is screwed to the center of the combustion chamber from the outside.

FIG. 2 is a sectional view taken along line II-II of FIG. 1, and FIG. 3 is a sectional view taken along line III-III of FIG. As shown in FIGS. 1 to 3, the crankcase 10 is provided with a reed valve device 26 as an intake valve device for each cylinder 18a. A surge tank 27 forming a part of the intake passage is provided upstream of the reed valve device 26.
Is arranged, and an intake pipe 29 having a throttle 28 is connected to the upstream side of the surge tank 27. A throttle opening sensor 30 for detecting the opening of the throttle 28 is provided outside the intake pipe 29. An air cleaner (not shown) is connected to the upstream side of the intake pipe 29.

A fuel injector 31 is attached to the surge tank 27 from the outside. The injector 31 is provided for each cylinder 18a, and is arranged so as to inject fuel toward the upstream side of each reed valve device 26.

On the other hand, the downstream side of the reed valve device 26 is connected to the crank chamber 10a inside the crankcase 10 and the scavenging port 32 formed in the cylinder block 9. The scavenging port 32 opens on the inner peripheral surface of the cylinder 18. Further, exhaust ports 33 are formed on the inner peripheral surface of the cylinder 18, and an exhaust passage 34 extends from these exhaust ports 33.

The exhaust passage 34a of the first cylinder 18a and the exhaust passage 34b of the second cylinder 18b join together on the way and extend to approximately the middle of the drive shaft housing 6. The exhaust passage 34c of the third cylinder 18c and the fourth
Similarly, the exhaust passage 34d of the cylinder 18d merges midway, extends to approximately the middle of the drive shaft housing 6, and merges with the exhaust passages 34a, 34b of the first and second cylinders 18a, 18b. The end of the exhaust passage 34 opens to the exhaust chamber 35 in the gear case 13, and the exhaust chamber 35 communicates with the final exhaust passage 36 formed around the propeller shaft 14.

By the way, the drive shaft housing 6
The lower half and the gear case 13 are submerged in water, and when the engine 1 is stopped, the lower half of the exhaust passage 34 and the exhaust chamber 35 are
Further, water has entered the final exhaust passage 36. When the engine 1 is operated, this water is pushed down by the exhaust pressure of the exhaust gas, and the exhaust gas is discharged into the water as shown by the solid arrow 37 in FIG. In addition, since the exhaust pressure is not high enough to push the water down when the engine is idling or operating at low speed, the exhaust gas passes through the bypass passage 39 formed in the drive shaft housing 6 as indicated by the broken arrow 38 in FIG. It is discharged from the auxiliary exhaust port 40 into the atmosphere.

The surge tank 27 arranged upstream of the reed valve device 26 is provided with an intake pressure sensor 41 which is a means for detecting intake pressure upstream of the crank chamber 10a, an atmospheric pressure sensor (not shown), and an intake temperature sensor. In the first embodiment of the present invention shown in FIG. 1, only one intake pressure sensor 41 is used, and its intake pressure detection hole 42 opens in the surge tank 27. Since the intake amount (intake amount) of air in each cylinder is slightly different, the intake pressure detection hole 42 is provided at a portion where the intake pressure is relatively stable, for example, at a location distant from the reed valve device 26.

Further, in the second embodiment of the present invention shown in FIG. 4, the number of intake pressure sensors 41 is the same as the number of cylinders, and four in this embodiment. The intake pressure detection hole 42 of each intake pressure sensor 41 corresponds to each cylinder 18a ...
It is provided just before 6.

Further, in the third embodiment of the present invention shown in FIG. 5, as in the second embodiment, the intake pressure detecting hole 42 of the intake pressure sensor 41 is connected to the reed valve device 26 of each cylinder 18a.
Although the number of cylinders of the intake pressure sensor 41 is equal to or less than the number of cylinders, for example, only one, and a solenoid valve or the like is provided in the middle of the intake pressure detection passage 43 connecting the intake pressure sensor 41 and the intake pressure detection hole 42. The switching valve 44 is provided.

Next, the operation of each embodiment of the present invention will be described.

The fuel injection amount from the fuel injector 31 is basically as shown in FIG. 6, the engine speed, the opening degree of the throttle 28, the intake pressure in the surge tank 27, the atmospheric pressure, the engine temperature, The cooling water temperature and the intake air temperature are detected by the respective sensors and input to the control unit 45. In the control unit 45, a microcomputer 46
Calculates the intake air amount based on each data, and after making various corrections, calculates the fuel injection amount, and the fuel injector 31
Output. In addition to the average value that has passed through a filter, etc., the average value of the negative pressure portion, the peak value and the average value of each engine revolution, the pressure at a constant crank angle instant, etc. Can be used.

In the first embodiment, the intake pressure detecting hole 42 of the intake pressure sensor 41 is provided in a portion of the surge tank 27 arranged upstream of the reed valve device 26 where the intake pressure is relatively stable. , Exhaust passage 3 due to various causes
The fuel injection amount can be controlled so that the optimum air-fuel ratio can be obtained even if the back pressure of 4 changes the intake amount. Further, unlike the conventional case, it is not necessary to detect the exhaust pressure which becomes high temperature and high pressure and the pressure in the crankcase 10, so that the intake pressure sensor 41 does not need to take pressure resistance, temperature resistance, water resistance and salt resistance into consideration. become,
The intake pressure sensor 41 has great merits in terms of cost, reliability, freedom of mounting position, mounting structure, and the like.

On the other hand, in the second and third embodiments,
The intake pressure sensor 4 is provided in front of the reed valve device 26 of the surge tank 27 arranged upstream of the reed valve device 26.
By providing the intake pressure detection hole 42 of No. 1, the engine 1 such as a multi-cylinder engine mounted on the outboard motor 2 is provided.
The length of the exhaust passage 34 of each cylinder 18a is different for each cylinder 18a.
It is possible to control the fuel injection amount for each cylinder 18a so that the optimum air-fuel ratio can be obtained even if the intake air amount varies. Further, when the pressure values of the cylinders 18a ... Are greatly differently detected before the engine 1 is started or at the time of idling, it may be determined that the sensor or the like has failed, and the sensor failure display may be performed. This method is applicable not only to the engine 1 of the outboard motor 2 but also to an engine whose back pressure changes due to some external factor.

By the way, when the intake pressure sensor 41 is provided for each cylinder 18a as in the second embodiment, since the intake pressure sensor 41 has a tolerance (error), the intake pressure sensor 41 increases as the number of cylinders increases. If the number of sensors is increased, the error may increase. Further, if the number of intake pressure sensors is increased, the cost will increase. Therefore, as in the third embodiment,
The number of intake pressure sensors 41 is smaller than the number of cylinders 18a, and a switching valve 44 is provided in the middle of an intake pressure detection passage 43 that connects the intake pressure sensors 41 and the intake pressure detection holes 42 to each other. If the intake pressure sensors 41 of a small number are used to detect the above, the above problem can be solved. In addition, a switching valve 4 for switching the atmospheric pressure detection passage (not shown)
If connected to No. 4, the atmospheric pressure sensor can be omitted. The switching valve 44, as shown in FIG.
The intake pressure detection passage 43 is switched by a drive signal from the control unit 45 to guide the pressure of each cylinder 18a to the intake pressure sensor 41.

The structure of the third embodiment will be described below with reference to the flow chart shown in FIG. First, in step 1 and step 2 (hereinafter, referred to as S1, S2 ...) The throttle 2
The opening degree of 8 and the rotation speed of the engine 1 are detected, and the basic intake air amount is calculated in S3. Further, in S4, a correction coefficient is calculated from the data of the intake air temperature, atmospheric pressure, engine temperature, etc. detected by other sensors, and the basic intake air amount obtained in S3 is corrected.
The intake air amount obtained in S4 is further corrected in S5 by a correction coefficient (described later) for each cylinder 18, and each cylinder 18a
The final fuel injection amount for each cylinder is calculated and the fuel is injected for each cylinder 18 in S6.

The correction coefficient for each cylinder 18 is from S7 to S.
Obtained by repeating steps up to 18. Specifically, first, preparation is made to detect the intake pressure of the first cylinder 18a by controlling the switching valve 44 (electromagnetic valve) in S7. Since the pressure is unstable immediately after the switching of the valve, after a certain delay (S8), the crank angle is detected by the engine speed sensor 23 (S9), and the first rotation of the engine 1 at a predetermined speed is performed.
The intake pressure of the cylinder 18a is detected and calculated in S10, and S1
The correction coefficient of the first cylinder 18a is calculated from the difference from the average value described later in 1. After the correction coefficient of the first cylinder 18a is calculated, the solenoid valve is controlled in S12 to prepare to detect the intake pressure of the next cylinder (Nth cylinder).
In 13 to S16, the correction coefficient of the Nth cylinder is calculated. Then, after the intake pressures of all the cylinders 18a are detected and calculated, the average pressure value of all the cylinders 18a is calculated in S17,
A correction coefficient for each cylinder 18a ... Is calculated from the pressure difference from this pressure average value in S18, and is output to S5. At the same time, the flow returns to S7 to detect the intake pressure of each cylinder 18a in order from the first cylinder 18a.・ Repeat calculation.

As in the second embodiment, when the pressure values of the cylinders 18a are greatly different before the engine 1 is started or when the engine is idling, it is determined that the sensor or the like has failed and the sensor failure is displayed. May be. Although not shown in detail, when the second and third embodiments are applied to a four-cycle engine, the intake pressure detection hole 42 of the intake pressure sensor 41 is provided in the intake passage upstream of the intake valve. The same effect as the two-cycle engine 1 described above can be obtained.

By the way, in the engine 1 of the outboard motor 2 as shown in FIG. 1, the lengths of the exhaust passages 34 extending from the respective cylinders 18a ... Engine 1
The length of the exhaust passage 34 differs among the cylinders 18a ... And the back pressure of the exhaust passages 34a. Therefore, if the intake air amount of each cylinder 18a for each engine speed is obtained in advance by an experiment or the like, and the data is used as a correction coefficient to calculate the fuel injection amount, and the fuel injection amount is output to the fuel injector 31, the above problem can be solved. Is. This method is applicable not only to the engine 1 of the outboard motor 2 but also to an engine in which the back pressure in the exhaust passage changes due to some external factor.

Further, in the engine 1 of the outboard motor 2 as shown in FIG. 1, the propeller shaft 14 can be rotated forward and backward by the shift mechanism 17 for the purpose of use. It is also possible to bring the propeller shaft 14 into a neutral state in which it does not rotate.

Since the hull 3 advances when the propeller shaft 14 rotates forward, the pressure of the final exhaust passage 36 formed around the propeller shaft 14 decreases, and exhaust gas is easily discharged. Therefore, the back pressure in the exhaust passage 34 extending from the cylinder 18 also decreases, and the intake amount increases. on the other hand,
Since the hull 3 moves backward when the propeller shaft 14 rotates in the reverse direction, the pressure in the final exhaust passage 36 increases due to water pressure,
Exhaust gas is difficult to discharge. Therefore, the back pressure in the exhaust passage 34 extending from the cylinder 18 also increases and the intake amount decreases. On the other hand, when the propeller shaft 14 is in neutral, the engine 1 has a low rotational speed, so the exhaust pressure is not high enough to push down the water sufficiently, and the exhaust gas is discharged from the auxiliary exhaust port 40 to the atmosphere through the bypass passage 39.

As described above, since the intake air amount changes depending on the shift position of the shift mechanism 17, the intake air amount for each engine speed depending on the shift position is previously obtained by an experiment or the like, and this data is detected by the shift position sensor as a correction coefficient. The above problem can be solved by calculating the fuel injection amount according to the shifted position and outputting it to the fuel injector 31.

In any of the embodiments, the output and fuel consumption can be improved by accurately detecting the intake amount of air and controlling the fuel injection amount to realize the optimum air-fuel ratio.

[0047]

As described above, according to the fuel injection type engine of the present invention, the basic air amount is calculated based on the opening degree of the throttle and the engine speed, and the upstream intake passage of the intake valve device is obtained. In a fuel injection type engine in which an appropriate amount of fuel is injected into the engine, an intake pressure detecting means is provided on the upstream side of the intake valve device, and the injection amount of the fuel is determined based on the detected intake pressure. Since it is configured to correct, even if the back pressure in the exhaust passage changes the intake amount due to various causes, it is possible to control the fuel injection amount so that the optimum air-fuel ratio can be obtained by the relatively stable intake pressure. The engine output and fuel consumption can be improved.

Further, it has a plurality of cylinders adapted to obtain a basic air amount based on the throttle opening and the engine speed and inject an appropriate amount of fuel into the upstream intake passage of the intake valve device. In a fuel injection engine, an intake pressure detecting means is provided immediately before the intake valve device of each cylinder, and the fuel injection amount to each cylinder is corrected based on the detected intake pressure of each cylinder. Therefore, even if the intake air amount of each cylinder varies, it is possible to control the fuel injection amount for each cylinder so that the optimum air-fuel ratio can be obtained.
The engine output and fuel consumption can be improved.

Further, it has a plurality of cylinders for determining a basic air amount based on the throttle opening and the engine speed and injecting an appropriate amount of fuel into the upstream intake passage of the intake valve device. In a fuel injection engine, intake pressure detection holes are provided in front of the intake valve devices of the respective cylinders, and these detection holes are connected to intake pressure detection means of a number equal to or less than the number of cylinders via an intake pressure detection passage. At the same time, the intake pressure detecting means is provided with a switching valve in the middle of the intake pressure detecting passage to selectively detect the intake pressure of each cylinder, while the cylinders are detected based on the detected intake pressure of each cylinder. Since it is configured to correct the fuel injection amount to each cylinder, the fuel injection amount can be controlled for each cylinder so that the optimum air-fuel ratio can be obtained even if the intake air amount of each cylinder varies, and the number of cylinders Where there are many It can reduce the tolerance of the intake pressure detecting means, thereby improving the enhancement and fuel consumption of the engine output.

Furthermore, the basic air amount is calculated based on the throttle opening and the engine speed, and an appropriate amount of fuel is injected into the upstream intake passage of the intake valve device, and a plurality of In a fuel injection type engine having cylinders and different lengths of exhaust passages extending from the respective cylinders, an intake amount of each cylinder for each engine speed is previously obtained by an experiment etc. Since the fuel injection amount to each cylinder is corrected based on the above, even if the back pressure of each exhaust passage is different and the intake air amount of each cylinder varies, an optimum air-fuel ratio can be obtained. The fuel injection amount can be controlled for each cylinder, and the engine output and the fuel consumption can be improved.

Then, the basic air amount is obtained based on the throttle opening and the engine speed, and an appropriate amount of fuel is injected into the upstream intake passage of the intake valve device, and the shift mechanism is set. In a fuel injection engine that has a driven body that is driven by the engine and can be rotated in the forward and reverse directions by the shift mechanism, an intake amount for each engine speed depending on the shift position of the shift mechanism is previously obtained by an experiment or the like. Since the fuel injection amount is corrected based on this intake air amount, even if the intake air amount changes depending on the shift position, the fuel injection amount can be controlled so that the optimum air-fuel ratio can be obtained, and the engine output It is possible to improve the fuel efficiency, the fuel efficiency, and the fuel efficiency.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of an outboard motor equipped with a fuel injection engine according to the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a vertical sectional view of a surge tank showing a second embodiment of the present invention.

FIG. 5 is a vertical sectional view of a surge tank showing a third embodiment of the present invention.

FIG. 6 is a basic configuration diagram of fuel injection amount control.

FIG. 7 is a flowchart showing a configuration of fuel injection amount control according to a third embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 engine 2 outboard motor 6 drive shaft housing 10 crankcase 12 crankshaft 13 gear case 14 propeller shaft (driven body driven by engine) 15 drive shaft 16 propeller 17 shift mechanism 18 cylinder (cylinder) 23 engine speed sensor 26 lead Valve device (intake valve device) 27 Surge tank (intake passage) 28 Throttle 29 Intake pipe 30 Throttle opening sensor 31 Fuel injector 34 Exhaust passage 41 Intake pressure sensor (intake pressure detection means) 42 Intake pressure detection hole 43 Intake pressure detection Passage 44 Switching valve 45 Control unit

Claims (5)

[Claims] 1. A fuel injection engine in which a basic air amount is obtained based on a throttle opening and an engine speed, and an appropriate amount of fuel is injected into an upstream intake passage of an intake valve device. A fuel injection engine characterized in that an intake pressure detecting means is provided on the upstream side of the intake valve device, and the injection amount of the fuel is corrected based on the detected intake pressure. 2. A plurality of cylinders adapted to obtain a basic air amount based on a throttle opening and an engine speed and inject an appropriate amount of fuel into an upstream intake passage of an intake valve device. In a fuel injection engine, an intake pressure detecting means is provided immediately before the intake valve device of each cylinder, and the fuel injection amount to each cylinder is corrected based on the detected intake pressure of each cylinder. A fuel injection engine characterized by the above. 3. A plurality of cylinders adapted to obtain a basic air amount based on a throttle opening and an engine speed and inject an appropriate amount of fuel into an upstream intake passage of an intake valve device. In a fuel injection engine, an intake pressure detection hole is provided in front of each intake valve device of each cylinder.
These detection holes are connected to intake pressure detecting means of a number equal to or less than the number of cylinders through an intake pressure detecting passage, and the intake pressure detecting means is provided with a switching valve in the middle of the intake pressure detecting passage to provide the cylinders with the respective cylinders. Is selectively detected, while the fuel injection amount to each cylinder is corrected based on the detected intake pressure of each cylinder. 4. A basic air amount is obtained based on a throttle opening and an engine speed, and an appropriate amount of fuel is injected into an upstream intake passage of an intake valve device.
In a fuel injection engine that has a plurality of cylinders and the lengths of the exhaust passages extending from the respective cylinders are different,
A fuel injection engine, characterized in that an intake air amount of each cylinder for each engine speed is obtained in advance by experiments and the fuel injection amount to each cylinder is corrected based on the intake air amount. 5. A basic air amount is obtained based on a throttle opening and an engine speed, and an appropriate amount of fuel is injected into an upstream intake passage of an intake valve device, and
In a fuel injection engine having a shift mechanism, in which a driven body driven by the engine can rotate forward and backward by the shift mechanism, an intake amount for each engine speed depending on a shift position of the shift mechanism in advance through experiments or the like. Is obtained, and the fuel injection amount is corrected based on the intake air amount.