JP2548393Y2 - Control device for internal combustion engine - Google Patents

Description

The present invention relates to a control device for an internal combustion engine, and more particularly to a control device for an internal combustion engine having a hydraulically driven intake valve.

(Prior Art) An internal combustion engine in which a hydraulic driving mechanism is interposed between a valve driving cam and an intake valve, and the opening and closing timing of the intake valve can be arbitrarily set by controlling the hydraulic pressure of the driving mechanism. Is conventionally known (for example, JP-A-61-275516).

(Problems to be Solved by the Invention) Since such a drive mechanism using hydraulic pressure does not operate when the operating hydraulic pressure is low, the following problems remain when starting the engine.

When the engine is stopped, the operating oil pressure is low,
When the engine is started, there is a time delay before the operating oil pressure rises from a low state and the drive mechanism becomes operable. In other words, there is a time delay from the start of the engine to the start of the normal valve operation due to the delay in the supply of the hydraulic oil, which depends on the viscosity of the hydraulic oil, the shape of the oil passage, the performance of the oil pump, and the like. For this reason, immediately after the start of the engine start, the valve does not operate at all or the lift amount is small, and at this time, the fuel injected into the intake pipe accumulates in the intake port or becomes an rich mixture. There is still room for improvement in the starting characteristics and the exhaust gas characteristics at the time of starting when the fuel is sucked into the cylinder.

The present invention has been made in view of the above points, and provides a control device for an internal combustion engine that can improve the starting characteristics and the exhaust gas characteristics at the time of starting of an engine having a hydraulically driven intake valve. With the goal.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a hydraulic chamber in which hydraulic oil is supplied by an oil pump driven by an internal combustion engine between a valve driving cam and an intake valve. Control device for an internal combustion engine having a hydraulically driven intake valve,
In a control device comprising start detection means for detecting the start of the engine, and lift amount detection means for detecting a lift amount of the intake valve, the lift amount of the intake valve at the time of starting the engine is controlled by the start of the engine. Fuel supply control means for determining whether or not the lift amount is equal to or less than a predetermined lift amount necessary for stopping the supply of fuel to the engine when the lift amount of the intake valve is equal to or less than the predetermined lift amount. It was made.

The fuel supply control means supplies fuel to the engine when the predetermined lift amount is exceeded when the engine is started.

When the engine is started, the supply of the ignition signal to the ignition plug of the engine is stopped when the lift amount is equal to or less than the predetermined lift amount, and the ignition signal is supplied when the lift amount exceeds the predetermined lift amount. It is preferable to provide ignition control means for supplying the ignition plug to the ignition plug.

(Operation) At the start of the engine, when the lift amount of the intake valve is equal to or less than the lift amount required for starting the engine, the fuel supply to the engine is stopped.

Further, when the lift amount exceeds a lift amount necessary for starting the engine, fuel is supplied to the engine.

When the engine is started, the ignition signal is not supplied while the fuel supply is stopped, and the supply of the ignition signal is started at the same time as the fuel supply is started.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing the main part of an internal combustion engine and its control device according to the present invention.

In FIG. 1, for example, a cylinder head 1 of a four-cylinder type internal combustion engine E is provided with an intake valve port 3 that opens to the top of a combustion chamber 2 of the internal combustion engine and communicates with an intake port 4 on the other. I have. The intake valve 5 is arranged so as to be movable in the vertical direction in the figure in the cylinder head 1 to open and close the intake valve port 3. A valve spring 7 is contracted between the flange 6 of the intake valve 5 and the cylinder head 1, and the intake valve 5 is biased upward (in the valve closing direction) by the spring 7. You.

On the other hand, above the cylinder head 1, a cam shaft 9 having a cam 8 is rotatably disposed. This camshaft 9
Is connected to a crankshaft (not shown) via a timing belt (not shown). A plurality of hydraulically driven valve units 10, which will be described in detail later, are interposed between the cam 8 formed integrally with the cam shaft 9 and the intake valve 5 for each cylinder (first).
Only one hydraulic drive valve unit is shown in the figure). The hydraulic drive valve unit 10 includes an oil tank 11 and an oil pump 12
A hydraulic signal is supplied through an oil passage 13 and a control signal (θ _OFF , θ _ON ) for controlling a closing timing of the intake valve 15 and the like is supplied from an electronic control unit (hereinafter referred to as “ECU”) 14. You.

In this embodiment, a valve mechanism similar to that of the intake valve is provided on the exhaust valve 15 side (not shown), but the exhaust valve side normally closes at a constant timing according to the cam profile. It may be a mechanism.

A lift sensor 18 for detecting a lift amount of the intake valve 5 is provided near the flange 6 of the intake valve 15, and a detection signal thereof is supplied to the ECU 14.

A cylinder discrimination sensor (hereinafter, referred to as “CYL sensor”) 19 that outputs a signal pulse (hereinafter, referred to as “CYL signal pulse”) at a predetermined crank angle position of a specific cylinder is arranged on a holder (not shown) of the cam shaft 9. In addition, a TDC signal pulse is applied to the crankshaft of the engine at a crank angle position before a predetermined crank angle with respect to the top dead center (TDC) at the start of each cylinder's intake stroke (every 180 ° crank angle in a four-cylinder engine). A TDC sensor 20 that generates a crank angle sensor (hereinafter referred to as a “CRK sensor”) that generates one pulse (hereinafter referred to as a “CRK signal pulse”) at a constant crank angle (eg, 20 °) cycle shorter than the cycle of the TDC signal pulse. 21) is attached. These sensors 19 to 21 are electrically connected to the ECU 14, and a CYL signal pulse, a TDC signal pulse, and a CRK signal pulse are sent to the ECU 14. The output signal pulses of these three sensors 19, 20, 21 are used for various timing controls such as the closing timing of the intake valve, the fuel injection timing, the ignition timing, etc., and the detection of the engine speed.

The ECU 14 also includes an accelerator opening sensor (θ _ACC sensor) 22 that indicates the amount of depression of an accelerator pedal as a request detecting means that indicates a driver's request for the engine, and an atmospheric pressure sensor that detects the atmospheric pressure (P _A ). P _a sensor) 23, an intake air temperature sensor (T _a sensor for detecting the intake air temperature (T _a)) 24, and respectively detecting the oil pressure (Poil) and oil temperature (Toil) of operating oil of the hydraulic drive valve unit 10 Oil pressure sensor (Poil sensor) 2
5. Oil temperature sensor (Toil sensor) 26, engine cooling water temperature (T
a water temperature sensor (Tw sensor) 27, an oxygen concentration sensor (O ₂ sensor) 28 for detecting the oxygen concentration in the exhaust gas to detect the w) is electrically connected, the output signals from these sensors 22 to 28 is the ECU14 It is supplied to.

Further, the ECU 14 detects the output voltage (V _B ) of the battery and detects the start (cranking) of the engine based on the ON signal of the starter switch 17.

The ECU 14 includes a central processing unit, a memory, a control signal output circuit, and the like (not shown). Based on the detection signals from the various sensors 18 to 28 and the output voltage (V _B ) of the battery, the hydraulic drive valve unit 10 Control signals (θ _OFF , θ _ON ) to the engine and the amount of fuel supplied to the engine (fuel injection valve 29
Open time of) T _OUT, determines the ignition timing theta _IG of the spark plug 30 at an optimum value according to the operating state of the engine. Note that the fuel injection valve 29 is disposed slightly upstream of the intake port 4 of the intake pipe.

The hydraulic drive valve unit 10 is mounted for each cylinder corresponding to each of an intake valve and an exhaust valve, and as shown in FIG.
Hydraulic drive mechanism 51 that opens and closes by pressing downward against
And a hydraulic release mechanism 52 that invalidates the pressing force of the hydraulic drive mechanism 51 during the valve opening operation and thereby closes the intake valve 5 regardless of the cam profile.

The hydraulic drive mechanism 51 includes a cylinder body 53 fixed to a block 1a integrally formed with the cylinder head 1 and an intake valve 5
A valve-side piston 54 abutting on the upper end of the cylinder body 53 and swingably fitted to the lower part of the cylinder body 53;
A cam-side piston 56 slidably fitted to the upper portion of the cylinder body 53 with the upper end abutting on the lifter 55, and the cylinder body 53, the valve-side piston 54, and the cam-side piston 56. And a hydraulic oil chamber 57 as a main component.
When the oil pressure in 57 is equal to or higher than a predetermined value, the intake valve 5 is opened and closed according to the profile of the cam 8. The hydraulic oil chamber 57 communicates with an oil passage 58 of the hydraulic pressure release mechanism 52.

On the other hand, an oil pressure release mechanism 52 includes an oil passage 58 that connects the hydraulic oil chamber 57 and the oil supply gallery 61 via a feed valve 62 and a check valve 63, and a spill valve 59 that is provided in the middle of the oil passage 58.
And a feed valve 62 and a check valve 63 arranged in the oil passage 58.
And an accumulator 60 for maintaining the oil pressure in the accumulator circuit 58a defined by these valves 62 and 63 and the spill valve 59 at a predetermined value as main components. The refueling gallery 61 is provided to supply hydraulic pressure to a hydraulic drive valve unit provided for each cylinder, and is connected to the oil passage 13 via a pressure adjusting unit 64. The pressure adjustment unit 64
It is provided for adjusting the oil pressure pressurized by the oil pump 12 to an oil pressure within a predetermined range.

As shown in FIG. 3, the spill valve 59 has a first valve body.
A pilot valve 69 comprising a first valve seat 69a and a first valve seat 69b;
The main components of the main valve 73 include a valve body 73a and a second valve seat 73b, and a solenoid 71 for moving the first valve body 69a. The first valve body 69a is formed integrally with the rod 68 and the armature 67, and is slidably fitted in a cylinder hole 66 formed in the housing 65. First valve body 69
A spring 70 is contracted between a and the first valve seat 69b,
The first valve body 69a is provided with a hole 69c and an oil passage 69d for allowing oil in the hydraulic chamber 75 to leak from the outlet port 78 when the valve body moves upward and is in a valve-open state. I have. The main valve 73 is provided below the pilot valve 69 so as to connect / disconnect the first port 76 and the second port 77 to each other.
A spring 74 is contracted between the valve body 73a and the first valve seat 69b so as to press the 73a downward. Further, the valve body of the main valve 73
An orifice hole 73c is provided in 73a.

The solenoid 71 is disposed in the chamber 65b of the housing 65, and is connected to the ECU 14.

Further, the accumulator 60 is provided in the middle of the accumulator circuit 58a to maintain the oil pressure in the accumulator circuit 58a at a predetermined pressure, a cylinder hole 80 formed in the block 1a, and a cap 81 having an air hole 81a, Piston 82 slidably fitted in cylinder hole 80, cap 81 and piston 82
And a spring 83 contracted between them.

The operation of the hydraulic drive mechanism 51 and the hydraulic release mechanism 52 configured as described above will be described below.

When the solenoid 71 is energized by a control signal from the ECU 14, the valve body 69a of the pilot valve
Against the force of the armature 67 and the rod 68, the pilot valve 69 is closed (the moving amount of the valve body 69a is very small, so even when the pilot valve is closed, The gap between the upper end of the valve body 69a and the housing 65 in FIG. 3 is very narrow). At this time, the oil pressure on the first port 76 side is equal to the oil pressure on the hydraulic chamber 75 side, and the spring 74
With this force, the second valve body 73a is pressed downward, and the main valve 73 is closed. As a result, the hydraulic oil chamber of the hydraulic drive mechanism 51
The hydraulic pressure in 57 is maintained at a high pressure (not less than a predetermined value), and the opening and closing drive of the intake valve 5 according to the profile of the cam 8 is performed.
Valve operating characteristics in this case (crank angle θ and valve lift amount Li
The relationship with f is, for example, as shown by the broken line in FIG.

On the other hand, when the solenoid 71 is deenergized, the first valve body 69a moves upward by the force of the spring 70, and the pilot valve 69 is opened. As a result, the oil in the hydraulic chamber 75 is
The air is discharged through the outlet port 78, the second valve body 73a moves upward, and the main valve 73 is driven to open. as a result,
The hydraulic pressure in the hydraulic oil chamber 57 of the hydraulic drive mechanism 51 drops, and the cam 8
, The intake valve 5 starts the valve closing operation. Accordingly, for example, when the solenoid 71 is deenergized at the crank angle θ _OFF shown in FIG. 4, the valve operating characteristics shown by the solid line are obtained.

As described above, the solenoid 71 is deenergized or energized by the control signal from the ECU 14, and the operation of the hydraulic drive mechanism 51 is invalidated at the time of the deactivation, whereby the closing start timing of the intake valve 5 can be arbitrarily set. Can be set. As a result, the intake air amount of each cylinder can be controlled by the control signal of the ECU 14.

FIG. 5 is a flowchart showing a procedure for determining the fuel supply amount T _OUT and the ignition timing θ _IG .

In step S1, the engine is cranking (starting)
Is determined. In this embodiment, this determination is made by determining whether or not the star switch 17 is turned on. For example, whether or not the engine speed is equal to or lower than a predetermined speed, The determination may be made based on whether or not the value is equal to or more than the value, or whether or not the position of the starter rack is at the cranking position.

When the answer to step S1 is negative (No), that is, when cranking is not being performed, the process proceeds to step S3 to perform basic mode control. In the basic mode control, the reference values of the fuel supply amount T _OUT and the ignition timing θ _IG are read from a map set according to the engine speed Ne and the accelerator opening θ _ACC ,
This reference value is corrected using a correction term determined according to the detection signals from the various sensors to calculate the fuel supply amount T _OUT and the ignition timing θ _IG , and based on the calculation results, the fuel injection valve
A drive signal is output to 29 and the ignition plug 30.

When the answer to step S1 is affirmative (Yes), that is, during cranking, the detected lift amount Lif of the intake valve is reduced to a predetermined value Lo.
It is determined whether or not it is below (step S2). When this answer is affirmative (Yes), that is, when Lif ≦ Lo holds, the intake valve 5 is not opened at all or is slightly opened, and the mixture is sucked into the cylinder. Since it is not or insufficient, the supply of the fuel and the supply of the ignition signal to the ignition plug are stopped (steps S5 and S6).

As a result, it is possible to prevent the fuel injected into the intake port 4 from staying and deteriorating the starting characteristics and the exhaust gas characteristics. Also, by stopping the supply of the ignition signal at the same time, the power consumption of the battery can be reduced.

When the answer to step S2 is negative (No), that is, when Lif> Lo is satisfied, since a sufficient lift amount of the intake valve has been obtained, the process proceeds to step S4 to perform start mode control. In the start mode, the reference value of the fuel injection amount set according to the engine coolant temperature Tw is corrected by a correction term corresponding to the engine speed Ne and the battery voltage, and the fuel supply amount T _OUT is calculated. The ignition timing θ _IG is
The angle is set to be more advanced than in the basic mode. As a result, after a sufficient lift amount of the intake valve is secured, fuel supply and ignition suitable for starting the engine are performed until cranking ends, and good starting characteristics can be secured.

In the present embodiment, the determination as to whether or not the lift amount of the intake valve is sufficiently secured is made based on the detection signal of the lift sensor 18. However, the present invention is not limited to this. And whether the detected intake air amount is equal to or more than a predetermined amount, or whether the engine speed Ne is equal to or more than a predetermined number of revolutions, is determined. The determination may be made based on whether or not the above is true.

(Effects of the Invention) As described in detail above, the present invention has the following effects.

According to the control device of the first aspect, at the time of starting the engine, when the lift amount of the intake valve is equal to or less than a predetermined lift amount required for starting the engine, the fuel supply to the engine is stopped. It is possible to prevent the fuel from accumulating and deteriorating the starting characteristics or the exhaust gas characteristics at the time of starting.

According to the control device of the second aspect, when the lift amount of the intake valve exceeds the predetermined lift amount, a suitable amount of fuel is supplied to the engine at the time of starting the engine, so that good startability is ensured.

According to the control device of the third aspect, at the time of starting the engine, the ignition signal is not supplied while the supply of the fuel is stopped, and the supply of the ignition signal is started at the same time as the start of the fuel supply. You can save money.

[Brief description of the drawings]

FIG. 1 is a diagram showing a main part of an internal combustion engine and its control device according to the present invention, FIG. 2 is a diagram showing a valve operating mechanism of the engine of FIG. 1, and FIG. FIG. 4 is a diagram showing the operation characteristics of the intake valve, and FIG. 5 is a flowchart showing a procedure for determining the fuel supply amount and the ignition timing. 5 ... intake valve, 8 ... cam, 10 ... main pressure drive valve unit, 14 ... electronic control unit (ECU), 18 ...
Lift sensor, 19 ... Cylinder discrimination sensor, 20 ... TDC sensor, 21 ... Crank angle sensor, 22 ... Accelerator opening sensor, 51 ... Hydraulic drive mechanism, 52 ... Hydraulic release mechanism, 59 ...
Spill valve, 71 ... Solenoid.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-168950 (JP, A) JP-A-63-117149 (JP, A) JP-A-62-162753 (JP, A) 157143 (JP, U)

Claims (3)

(57) [Scope of request for utility model registration] A control device for an internal combustion engine having a hydraulically driven intake valve in which a hydraulic chamber to which hydraulic oil is supplied by an oil pump driven by the internal combustion engine is provided between a valve driving cam and an intake valve. In a control device including a start detection unit that detects start of the engine, and a lift amount detection unit that detects a lift amount of the intake valve, the lift amount of the intake valve when the engine is started, Fuel supply control having a determination means for determining whether or not the lift amount required for starting the engine is equal to or less than a predetermined lift amount, and stopping fuel supply to the engine when the lift amount of the intake valve is equal to or less than the predetermined lift amount; A control device for an internal combustion engine, characterized by comprising means. 2. The fuel supply control device according to claim 1, wherein the fuel supply control means supplies fuel to the engine when the lift amount of the intake valve exceeds the predetermined lift amount at the time of starting the engine. Control device for internal combustion engine. 3. When starting the engine, when the lift amount is equal to or less than the predetermined lift amount, supply of an ignition signal to a spark plug of the engine is stopped, and when the lift amount exceeds the predetermined lift amount. 3. The control device for an internal combustion engine according to claim 1, further comprising an ignition control means for supplying an ignition signal to said ignition plug.