JPS61286579A - Fuel-injection type engine - Google Patents

Abstract

PURPOSE:To make improvements in a restarting characteristic, by performing a fuel cut at the time of engine stalling, while scavenging the unburned fuel inside a cylinder by assist air, in case of an engine which leads the assist air into a surrounding of a fuel injection stream out of the fuel injection valve installed in a suction passage. CONSTITUTION:At the time of engine driving, cooling water temperature Tw by a water temperature sensor 23 is compared with the specified value Tw1 at a control unit 20, and when the temperature difference is Tw > Tw1, succes sively an engine speed N out of a distributor 22 is compared with an idle keep ing speed N1. And, at the time of normal driving in the temperature difference of N >= N1, a fuel injection quantity and an assist air quantity both are con trolled on the basis of a basic map. On the other hand, at the time of engine stalling when the temperature difference is N < N1, a control valve 17 is con trolled so as to cause a passage area of an assist air passage 14 to become the maximum, while fuel injection out of a fuel injection valve 11 is controlled so as to be stopped, whereby the unburned fuel in a combustion chamber 2 inside a cylinder is made so as to be restrained as low as possible.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a fuel injection type engine, and particularly to a fuel injection type engine in which assist air is introduced into a fuel injection flow from a fuel injection valve to atomize the fuel. The present invention relates to measures to prevent warm locking when the engine stalls using this assist air system.

(Prior Art) Conventionally, in fuel injection type engines, as disclosed in, for example, Japanese Unexamined Patent Publication No. 57-108460, an assist air passage has been provided in the vicinity of a nozzle portion of a fuel injection valve provided in an intake passage of the engine. By opening the assist air passage and introducing assist air around the fuel injection tJ4m from the fuel injection valve, the assist air system promotes fuel atomization and improves the combustion performance of the engine. What you have is known.

(Problem to be Solved by the Invention) By the way, in a fuel-injected engine, when the engine is warm and the engine speed drops below the idle speed due to ignition failure, etc., and the engine stalls, the ignition key switch is activated. Since fuel cut was not performed so that the engine could continue operating with the engine in the ON state, and the engine was stopped due to ignition failure, each cylinder was stopped in an unignited state. As a result, when the engine stalls, the fuel in the cylinder vaporizes and self-ignites, increasing the pressure in the cylinder, and the compression ratio appears to be low. Therefore, when restarting the engine from this stalled state, there is a problem in that the starter motor does not rotate even if it is turned, resulting in a so-called warm lock. Incidentally, when the engine is stopped by turning the ignition key switch OFF, fuel is cut, so there are few cylinders that stop in an unignited state, and warm lock almost never occurs.

The present invention has been made in view of this point, and focuses on the use of the above-mentioned assist air system.When the engine stalls, the fuel is cut and the unignited fuel in the cylinder is scavenged by the assist air. The purpose of this system is to promote fuel atomization using assist air during engine operation to ensure improved combustibility, while preventing warm engine lock when the engine stalls and improving restartability.

<Means for Solving the Problems> In order to achieve the above object, the solving means of the present invention includes a fuel injection valve that is provided in the intake passage and supplies fuel by injection, and a fuel injection valve that is disposed in the vicinity of the nozzle portion of the fuel injection valve. In a fuel injection type engine equipped with an assist air passage that opens at the center of the fuel injection valve and introduces assist air around a fuel injection flow from a fuel injection valve, a control valve is provided that adjusts a passage area of the assist air passage. Further, an engine temperature compensation detection means for detecting the temperature of the engine is provided. and an engine rotation speed detection means for detecting the engine rotation speed, and an output from both of the detection means, and when the engine rotation speed falls below the idle maintenance rotation speed at engine 21 hours, the fuel injection valve is activated. The present invention includes a control means for controlling the control valve so as to stop fuel injection and maximize the passage area of the assist air passage.

(Function) With the above configuration, in the present invention, during normal operation of the engine, assist air is introduced from the assist air passage around the fuel injection tJJ flow injected from the fuel injection valve, so that the assist air causes fuel atomization is promoted,
As a result of supplying sufficiently atomized fuel to the cylinders, its combustion is performed satisfactorily.

On the other hand, when the engine is warm and the engine speed drops below the idle maintenance speed, that is, when the engine stalls, fuel injection from the fuel injection valve is stopped and the area of the assist air passage is maximized. Since the above-mentioned fuel cut reduces the amount of unignited fuel in the cylinder, a large amount of assist air (outside air) supplied from outside the intake passage cools the inside of the cylinder and suppresses self-ignition. , and unignited fuel is scavenged out of the cylinder. As a result, an increase in cylinder pressure due to fuel vaporization or self-ignition within the cylinder is prevented, and subsequent restarts can be performed satisfactorily, and warm lock does not occur.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 shows an embodiment in which the present invention is applied to a four-cylinder engine, in which 1 is an engine, 2 is a combustion chamber in each cylinder of the engine 1, and 3 is an engine 1 whose upstream end is open to the atmosphere via an air cleaner 4. An intake passage for supplying intake air to each combustion chamber 2, and each intake passage 3 has an air flow meter 5 for detecting the amount of intake air and a throttle valve 6 for controlling the amount of intake air downstream of the air flow meter 5. A surge tank 7 is provided downstream of the throttle valve 6 in the intake passage 3, and branches from the surge tank 7 corresponding to each cylinder to independently supply the combustion chamber 2 of each cylinder. A branch intake passage 3a is provided which communicates with the. 8 is an intake valve provided at the opening of each branch intake passage 3a into the combustion chamber 2; 9 is an exhaust passage for discharging exhaust gas from each combustion chamber 2; 10 is each combustion chamber of the exhaust passage 9; This is an exhaust valve provided at the opening of chamber 2.

A fuel injection valve 11 is provided in each branch intake passage 3a to inject and supply fuel to each branch intake passage 3a. As shown in detail in FIG. 2, the multi-fuel injection valve 11 has a socket 1 inserted into a mounting hole 12 provided in the side wall of the branched intake passage 3a.
3, and the downstream end of the assist air passage 14 is located near the nozzle portion 11a of each fuel injection valve 11.
An annular space 14a provided on the outer periphery of the socket 13 corresponding to the nozzle portion 11a and a large number of ejection holes 14b, 14b, . . . and
The upstream ends of each of the assist air passages 14 are gathered together and open upstream of the throttle valve 6 of the intake passage 3 and downstream of the air flow meter 5, so that a part of the intake air is taken into the assist air passage 14 as assist air, and This assist air is introduced from the downstream end of the assist air passage 14 around the fuel injection stream injected from the nozzle portion 11a of each fuel injection valve 11 to promote atomization of the fuel. Note that 15 is a fuel passage that supplies fuel to each fuel injection valve 11. Further, in FIG. 2, 16 is a sealing material.

Furthermore, a control valve 17 is disposed in the middle of each of the assist air passages 14 to adjust the passage area of the assist air passage 14 to control the amount of assist air. The control valve 1
7 includes a valve body 18 that opens and closes the assist air passage 14 as shown in FIG. 2, and an actuator 19 that opens and closes the valve body 18 to adjust its opening degree.

A control unit 20 consisting of a CPU or the like is connected to one actuator of each of the fuel injection valves 11 and each control valve 17 to control the operation of these. Along with the intake air amount signal, a throttle opening signal (engine load signal) from a throttle opening sensor 21 that detects the opening of the throttle valve 6, and an engine rotation speed and crank angle signal from a distributor 22 as an engine rotation speed detection means. , as well as a water temperature signal (engine temperature signal) from a water temperature sensor 23 serving as an engine temperature detection means for detecting the engine temperature from the temperature of engine cooling water. Therefore, the control unit 20 controls the amount of intake air, the throttle opening (
The fuel injection amount from each fuel injection valve 11 is controlled according to the engine operating state based on signals such as engine load), cooling water temperature (engine temperature), engine speed, and crank angle. Accordingly, the amount of assist air is controlled by controlling the opening degree of the control valve 17, that is, the passage area of the assist air passage 14, so that the atomization is sufficiently promoted. Furthermore, when the engine is warm and the engine speed drops below the idle maintenance speed, that is, when the engine stalls, the fuel injection from the fuel injection valve 11 is stopped and the control is performed so that the amount of assist air is maximized. A control means 24 is configured to control the opening degree of the valve 17, that is, the passage area of the assist air passage 14 to the maximum.

Next, the operation of the control unit 20 when the engine stalls will be explained using the approach 1r shown in FIG.
After starting, first set the engine speed N1 at step $1.
After reading the signals of the cooling water temperature (engine temperature) TW and the intake air amount, in step S2, the cooling water ITw
is larger than a predetermined value TW+, and determines whether Tw≦T
If W+ is NO, it is determined that the engine is cold, and in step S3, the fuel injection tI4ffi and the assist air amount (assist air passage area) are controlled based on the basic map for when the engine is cold. On the other hand, 7w > Tw + YES
At the next step, it is determined that the engine is warm, and the next step S is performed.
4, the engine speed N is the idle maintenance speed N1
If the answer is No (N≧N1), it is determined that it is normal warm operation, and in step S5, the fuel injection amount and assist air amount are controlled based on the basic map during warm operation. do.

On the other hand, if the determination in step S4 is YES (N<N+), it is determined that the engine is stalled when the engine is warm and the engine speed is lower than the idle maintenance speed, and the assist air passage 14 is opened in step S6. The control valve 17 is controlled so that the passage area is maximized, and step Sy
The fuel injection valve 11 is controlled to stop fuel injection from the fuel injection valve 11 in preparation for a subsequent restart.

Therefore, in the above embodiment, during normal engine operation (including cold and warm times), a predetermined amount of fuel is injected from the fuel injection valve 11 according to the operating state, and this fuel By adjusting the opening degree of the control valve 17, that is, the passage area of the assist air passage 14, according to the amount of injection tA, a predetermined amount of assist air is injected around the fuel injection flow to promote atomization of the fuel. is sufficiently planned,
As a result, this atomized fuel is supplied to the combustion chamber 2 of each cylinder and combusted favorably, thereby significantly improving combustibility.

On the other hand, when the engine is warm and the engine speed drops below the idle maintenance speed, that is, when the engine is stalled, fuel injection from the fuel injection valve 11 is stopped, and the opening of the control valve 17, that is, the assist air passage. By maximizing the passage area of No. 14, the amount of unignited fuel in the combustion chamber 2 in the cylinder is suppressed by the above-mentioned fuel cut, and a large amount of assist air supplied from the assist air passage other than the intake passage 3, The combustion chamber 2 in the cylinder is cooled, self-ignition of the fuel in the combustion chamber 2 is suppressed at τ warm time, and unignited fuel in the combustion chamber 2 is scavenged to the exhaust passage 9.

This prevents the cylinder pressure from increasing due to fuel vaporization and self-ignition in the combustion chamber 2 of each cylinder, making it possible to perform subsequent restarts smoothly and efficiently. Interval lock can be reliably prevented.

(Effects of the Invention) As explained above, according to the present invention, in a fuel-injected engine equipped with an assist air system, when the engine stalls, the fuel is cut and the amount of assist air is maximized. While ensuring improved combustibility by promoting fuel atomization using assist air during operation, it is possible to improve restartability by preventing warm lock when the engine stalls.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is an overall schematic diagram, FIG. 2 is an enlarged view of the main parts, and FIG. 3 is a flow chart diagram showing the operation of the control unit. 3...Intake passage, 11...Fuel injection valve, 11a...
・Nozzle part, 14...Assist air passage, 17...
Control valve, 20... Control unit, 22...
Distributor (engine speed detection means), 23
...Water temperature sensor (engine salinity detection means), 24...
- Control means. Agent Patent Attorney Former 1) Hiroshi, 1. ,,=-:. J: 1:'hZ -1, -21

Claims (1)

[Claims] (1) A fuel injection valve that is installed in the intake passage and supplies fuel by injection, and an assist air that opens close to the nozzle part of the fuel injection valve and introduces assist air around the fuel injection flow from the fuel injection valve. A fuel injection type engine having a passage, a control valve that adjusts the passage area of the assist air passage, an engine temperature detection means that detects the temperature of the engine, and an engine rotation speed detection means that detects the rotation speed of the engine. In response to the outputs of both of the detection means, when the engine is warm and the engine speed falls below the idle maintenance speed, the fuel injection by the fuel injection valve is stopped and the passage area of the assist air passage is maximized. 1. A fuel injection type engine, comprising: control means for controlling the control valve so that