JPH06323169A - Control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To reduce a combustion noise at the time of specific operation of an internal combustion engine. CONSTITUTION:An engine is formed by providing the third valve 7 provided in a port 3c of opening its one end to a combustion chamber to connect the other end to an exhaust port 3b in addition to intake/exhaust valves 5, 6 of an internal combustion engine, drive means 10 to 18 for opening/closing the third valve and a control means 20 for controlling the drive means to open the third valve during the time of a little period after closing the intake valve in the beginning from an exhaust stroke to a compression stroke when placed in a condition of specific operation by detecting an operation condition of the internal combustion engine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an internal combustion engine which is designed to reduce noise during specific operation of the internal combustion engine, particularly during idle operation.

[0002]

2. Description of the Related Art In an internal combustion engine, especially a diesel engine, it is preferable to set a high compression ratio (about 1/15) in order to improve fuel efficiency and reduce exhaust gas. During load operation, the ignition delay is shortened to reduce noise and there is no particular problem.

[0003]

However, when the compression ratio is high, problems such as an increase in combustion noise due to abrupt combustion and a deterioration in gear rattling noise due to an increase in engine rotation fluctuation occur in a low idle operation state. . This becomes a big problem in exhaust gas countermeasures. As a countermeasure against this, it is necessary to have a function that achieves a high compression ratio when the engine is loaded and a low compression ratio when the engine is idle.

The present invention has been made in view of the above points, and reduces the compression ratio during a specific operation and adds a slight exhaust gas recirculation (hereinafter referred to as "EGR") function to make combustion slower. An object of the present invention is to provide a control device for an internal combustion engine that reduces noise.

[0005]

In order to achieve the above object, according to the present invention, in addition to an intake valve and an exhaust valve of an internal combustion engine, a port having one end opened to a combustion chamber and the other end communicating with an exhaust port. And a drive means for opening and closing the third valve, an operating state of the internal combustion engine is detected, and the intake valve is closed from an exhaust stroke to an initial stage of a compression stroke when in a specific operating state. The control means controls the drive means to open the third valve until a short period of time elapses after the valve is opened.

[0006]

The control means controls the engine in a specific operation state, for example,
In the idle operation state, the drive means is controlled to control the drive means from the start of the exhaust stroke to the end of the intake stroke and a short period of time after the intake valve is closed at the beginning of the compression stroke. The valve is opened, and a small amount of exhaust gas is sucked into the combustion chamber to add the EGR function, and at the beginning of the compression stroke, the intake air is released to reduce the compression ratio. This makes combustion mild and reduces noise.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows a main part of a diesel engine to which the present invention is applied. An intake port 3a, an exhaust port 3b, and a port 3c are formed in a cylinder head 3 arranged on a cylinder block 2 of the engine 1. , The port 3c has one end open to the combustion chamber and the other end is the exhaust port 3b.
Is in communication with. Cylinder block 2 cylinder 2a
A piston 4 is fitted in the intake port 3, and an intake valve 5, an exhaust valve 6 and a valve 7 are provided in the intake port 3a, the exhaust port 3b and the port 3c, respectively. This valve 7 is called the third valve. The intake valve 5 and the exhaust valve 6 are driven by a valve mechanism (not shown).

A retainer 8 is fixed to the upper portion of the valve rod 7a of the valve 7, and a valve spring 9 is compressed between the retainer 8 and the cylinder head 3. The upper end of the valve rod 7a is fixed to the piston 11 of the slave cylinder 10, and the oil chamber 10a is provided with a check valve 12. The oil chamber 10 a is connected to the discharge port of the hydraulic pump 15 via the oil passage 13 and the one-way valve 14, and the suction port of the hydraulic pump 15 is connected to the oil tank 16. Further, the one-way valve 14 allows the hydraulic pressure to flow only from the hydraulic pump 15 toward the oil chamber 10a. Further, the oil passage 13 is connected to the oil tank 16 on the downstream side (discharging port side) of the one-way valve 14 via the oil passage 17, and the solenoid valve 18 is connected to the oil passage 17. The check valve 12 is connected to the oil tank 16.

The solenoid valve 18 is a normally open solenoid valve which is open when deenergized and closes when energized. Solenoid valve 18
Is opened, the hydraulic pressure discharged from the hydraulic pump 15 is applied to the one-way valve 14, the oil passage 17, and the solenoid valve 18 concerned.
Through the oil tank 16 and the slave cylinder 10
The oil pressure in the oil chamber 10a decreases and the valve 7 is closed by the valve spring 9. When the solenoid valve 18 is closed, the oil passage 17 is closed, and the hydraulic pressure discharged from the hydraulic pump 15 passes through the one-way valve 14 and the slave cylinder 10
Is supplied to the oil chamber 10a, and the piston 11 is pushed down against the spring force of the valve spring 9 to open the valve 7.

The control unit 20 includes a solenoid valve 18
Engine speed sensor, crank angle sensor, accelerator opening sensor (all not shown)
The operating state of the engine 1 is determined by the engine speed signal, the crank angle signal (TDC), and the accelerator opening signal input from the solenoid valve, and the drive signal is output when the engine 1 is in a specific operating state. Control 18 That is, the control unit 20 closes the electromagnetic valve 18 and opens the valve 7 during the exhaust stroke, the intake stroke, and the beginning of the compression stroke when the engine 1 is in the idle operation state. These valves 7, one-way valve 14, hydraulic pump 15,
The oil passage 17, the solenoid valve 18, and the control unit 20 constitute the control device of the present invention.

The operation will be described below with reference to the time chart of FIG. The intake valve 5 and the exhaust valve 6 are driven by a valve mechanism in synchronization with the intake, compression, expansion, and exhaust strokes of the engine 1 (FIGS. 2A and 2B). On the other hand, the control unit 20 opens the solenoid valve 18 when the engine 1 is in the acceleration or cruise operation state. Solenoid valve 1
When the valve 8 is opened, the hydraulic pressure discharged from the hydraulic pump 15 flows to the oil tank 16 through the one-way valve 14, the oil passage 17, and the solenoid valve 18, and the oil chamber 1 of the slave cylinder 10 is closed.
The oil pressure in 0a decreases. As a result, the valve 7 is closed by the spring force of the valve spring 9. Therefore, the control device does not function at all and does not affect the performance under engine load.

When the engine 1 is in the idling state, the control unit 20 controls the start of the exhaust stroke to the beginning of the intake stroke and the compression stroke, that is, when the intake valve 5 is closed, as shown in FIG. 2 (c). The electromagnetic valve 18 is closed and the valve 7 is opened until a short period ΔT elapses. That is, the control unit 20 closes the valve 7 with a slight delay from the closing timing of the intake valve 5. The control unit 20 opens the solenoid valve 18 and closes the valve 7 from the time ΔT at the beginning of the compression stroke to the end of the expansion stroke.

Since the valve 1 of the engine 1 is opened from the start of the exhaust stroke to the end of the intake stroke and after the intake valve 5 is closed at the beginning of the compression stroke, a short period ΔT has elapsed. As shown in FIG. 2 (d), the exhaust efficiency is improved in the exhaust stroke, the exhaust system residual gas is slightly sucked by blowback in the intake stroke, and the intake air sucked into the cylinder at the beginning of the compression stroke is increased. The compression ratio is reduced by escaping from the valve 7 to the exhaust port 3b. As a result, in the engine 1, the compression ratio is lowered, and a slight EGR function is added, the combustion in the combustion chamber becomes mild, and the combustion noise is reduced.

Further, this control device also functions as a synchronous power source device with a third valve. That is, when the accelerator pedal is released during running and the engine braking operation is started, the control unit 20 has the engine speed equal to or higher than a predetermined speed and the power switch (not shown) is turned on. In this case, a drive signal is output from a predetermined crank angle position near the top dead center of the compression stroke for a predetermined period (for example, a period in which the crank angle advances by 100 °) to close the solenoid valve 18 and open the valve 7. Let me speak. As a result, the compression work done by the engine during the compression stroke is
When the valve 7 is opened, it is released to the exhaust port, and the action of pushing down the piston 4 in the expansion stroke is lost, resulting in the absorbed horsepower of the engine. This increases the engine braking force.

[0015]

As described above, according to the present invention, it is possible to control the combustion during a specific operation without affecting the performance under load, and particularly when the engine is idling, the compression ratio is lowered and some EGR is performed. By adding a function, there is an effect that combustion can be made mild and engine noise can be reduced.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of an engine control device according to the present invention.

FIG. 2 is a time chart showing the operation of the engine control device of FIG.

[Explanation of symbols]

 1 Diesel engine 2 Cylinder block 3 Cylinder head 3a, 3b, 3c Port 5 Intake valve 6 Exhaust valve 7 Third valve 10 Slave cylinder 14 One-way valve 15 Hydraulic pump 18 Solenoid valve 20 Control unit

Claims (1)

[Claims] 1. An intake valve and an exhaust valve of an internal combustion engine, a third valve provided at a port having one end opened to a combustion chamber and the other end communicating with an exhaust port, and a drive for opening and closing the third valve. Means for detecting the operating state of the internal combustion engine, and controlling the drive means during a specific operating state from the exhaust stroke until a short period after the intake valve is closed at the beginning of the compression stroke. And a control means for opening the third valve.