JPS59224430A - Control of intake control valve - Google Patents

Abstract

PURPOSE:To prevent stagnation of engine revolution due to the concentration of mixed gas, by forming a plurality of intake passages for each cylinder and installing an intake control valve in one intake passage for each cylinder and opening said control valve on start. CONSTITUTION:An intake control valve 14 is installed in one intake passage for each cylinder of a 4-cylinder engine equipped with two intake valves 21 for each cylinder. A surge tank 17 and a subinjector 19 are installed on the upstream side of the control valve 14. Though said intake control valve 14 is closed to strengthen swirl during low speed operation the valve 14 is opened out start, and the concentration of the mixed gas due to the fuel adhering onto the valve is prevented, and the reduction of the number of revolutions immediately after starting is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intake control method for an engine having two intake passages in each cylinder, and particularly to improvement of low-temperature startability.

Conventionally, the intake passage leading to a single combustion chamber is divided into two, and by installing an intake control valve on one side and controlling this, it is possible to achieve both an increase in torque in the low rotation range and an increase in torque in the high rotation range. There was a way.

The control method is, for example, as shown in FIG. 2, in which the opening and closing of the intake control valve is controlled at a predetermined set rotational speed or a predetermined amount of air (not shown). However, when the above-mentioned intake control valve system is introduced into an internal combustion engine that has a sub-injector for cold starting in the intake pipe gathering part as shown in Fig. 1, the generation of negative pressure during cranking is small.
There was a problem in that half of the fuel injected from the sub-injector during startup ended up in the vicinity of the closed valve and was not supplied to the combustion chamber. Then, when the engine is completely started, this adhering fuel is supplied to the combustion chamber as negative pressure is generated. As a result, there was a problem in that the air-fuel ratio immediately after starting became excessively rich for a moment, and the rotational behavior immediately after starting became unstable.

Therefore, in view of the above problems, the present invention significantly reduces fuel adhesion near the intake control valve of the sub-injector by opening the intake control valve, which is normally closed at low rotation speeds, only at the time of startup or for a certain period of time after startup. The purpose is to reduce this and stabilize rotational behavior after startup.

An embodiment of the present invention will be described below based on the drawings.

FIG. 4 is an overall configuration diagram of an internal combustion engine implementing the present invention. 1 is an internal combustion engine main body, 2 is a distributor 1 having a built-in rotation angle sensor, and 3 is a pressure sensor. 4 is a linear throttle sensor, 5 is a water temperature sensor, and 6 is an 02 sensor. 7 is an intake air temperature sensor, and 8 is an engine control unit incorporating a microcomputer. 9 is an ignition coil integrated with an igniter, 10 is an injector that injects fuel, 11 is a throttle valve, and 12 is a throttle valve 1
This is an air valve that controls the amount of air that bypasses 1.

13 is a variable intake system, and 14 is an intake control valve.

Further, FIG. 1 shows the relationship among the intake valve, intake control valve, sub-injector, etc. in more detail. FIG. 1 shows a four-cylinder engine. There are two intake valves 21 and two exhaust valves 22 at the top of the combustion chamber.
There is. Two intake pipes are provided from the surge tank 17 to each cylinder, and one of the intake pipes is provided with the above-mentioned intake control valve. In this engine, as shown in Figure 2, the intake control valve is closed at low speeds to increase the intake speed, and the swirl effect and intake inertia increase torque at low speeds, and the intake control valve is closed at high speeds. It is adapted to open to make it easier to take in air and increase torque in the high rotation range.

However, during the adaptation of this engine, as shown in Figure 5,
A phenomenon was discovered in which the engine speed temporarily dropped immediately after starting. As a result of analyzing the cause of this, it was found that, as mentioned above, the adhering fuel was sucked into the cylinder due to the generation of negative pressure, resulting in an excessively rich air-fuel ratio. In other words, if the intake control valve is closed when starting the engine, the generation of negative pressure in the engine is small during cranking, so the sub-injector 1 for low-temperature starting is installed upstream of the intake control valve.
A part of the fuel injected from the control valve 9 ends up adhering to the upstream side of the control valve. Next, when the engine reaches a complete explosion, negative pressure is suddenly generated, and this adhering fuel is sucked into the engine combustion chamber 20. As a result, the mechanism by which the instantaneous air-fuel ratio becomes excessively rich immediately after the engine starts, resulting in sluggish engine rotation as shown in FIG. 5, was clarified.

Therefore, the present invention solves the above problem by detecting the starting state of the engine by the control unit 8 that controls the intake control valve 14 in the system shown in FIG. Resolved the point.

In FIG. 3, the control unit 8 controls the starter signal (ST
A) is taken in, and it is determined in step sI whether or not it is in the starting state. If the start switch is ON, it is determined that the engine is starting, and the process proceeds to step s2.

In step S2, a control signal is output to open the intake control valve, and the control signal is sent from the control unit 8 to the solenoid valve 1 of the actuator.
5 to open the intake control valve.

On the other hand, when it is determined in step Sl that the engine is not in the starting state, the process advances to step s3. In step s3, it is determined whether or not the rotation speed is equal to or higher than a set value using the rotation speed data acquired in another routine. If the rotational speed is equal to or higher than the set value, the process proceeds to step s2 and the intake control valve is opened in the same manner as in the previous case. If it is determined in step S3 that the rotational speed is not greater than the set value, the process proceeds to step s4, where the intake control valve is controlled to close.

Here, the determination in step s3 may be made based on the intake air amount rather than the rotational speed. Alternatively, a value that combines the rotational speed and the intake pipe negative pressure may be used.

By performing the above control, the intake pipe at the front is drawn into the combustion chamber even during startup, so even if a complete explosion occurs, it will not become over-rich, and the engine speed will be prevented from becoming sluggish. have an effect.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of intake control valve installation, Figure 2 is a torque characteristic diagram when controlling the intake control valve, Figure 3 is a flowchart of intake valve control, Figure 4 is a schematic diagram of the entire system configuration, FIG. 5 is an engine rotation characteristic diagram at the time of starting. l...Engine body, 2...Distributor. 3...Pressure sensor, 4...Linear throttle sensor. 5... Water temperature sensor, 6... O2 sensor, 7 River intake temperature sensor, 8... Engine control unit, 9 River coil W
/igniter, 1o...injector, 11...throttle valve, 12...air valve, 13...variable intake system, 14...intake control valve, 15...
- Solenoid valve, 17... surge tank, 18... intake passage, 19... sub-injector. Representative Patent Attorney Takashi Okabe

Claims (1)

[Claims] In an engine having a plurality of intake passages for one intake, an intake control valve is provided in one intake passage for each cylinder, and the intake control valve is opened at startup. How to control the valve.