JP2001303997A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the degree of freedom of the working angle for a practical use of a suction valve or an exhaust valve. SOLUTION: Provided an opening time corresponding to a working angle (i.e., a minimum working angle) is T1 when a full opening holding time of the exhaust valve is '0', and when an opening time (an opening period) corresponding to the target operation angle of an exhaust valve is Tθ, the opening timing of a second exhaust valve is worked and controlled by delay by (Tθ-T1) from the opening timing of a first exhaust valve, and the two exhaust valves are worked at a minimum working angle in a way that a full opening holding time is set to '0'.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine capable of increasing a degree of freedom in setting a target operating angle of an intake valve or an exhaust valve.

[0002]

2. Description of the Related Art In an internal combustion engine, the operating angle of an intake / exhaust valve can be changed, and by changing the operating angle, intake characteristics or exhaust characteristics can be changed. There is something.

[0003] For example, Japanese Patent Application Laid-Open No. 8-2000025 discloses an internal combustion engine having a plurality of exhaust valves in one cylinder.
The operating angle of the exhaust valve can be varied by opening only one of the exhaust valves according to the operation state of the internal combustion engine, or by opening both exhaust valves by changing the opening timing relatively. Are disclosed.

[0004]

However, in the internal combustion engine disclosed in the above publication, the operating angle of each exhaust valve is not changed, and both exhaust valves are opened by changing the opening timing relatively. Even when the valve is opened, the relative shift of the valve opening timing is determined in one way, so that the operating angle of the exhaust valve cannot be set to an arbitrary value.

SUMMARY OF THE INVENTION The present invention has been made in view of such problems of the prior art, and an object of the present invention is to set the operating angle of an intake valve or an exhaust valve to an arbitrary value. It is an object of the present invention to provide an internal combustion engine.

[0006]

The present invention has the following features to attain the object mentioned above. That is, the present invention
In an internal combustion engine in which at least one of an intake valve and an exhaust valve is provided in a plurality of cylinders in one cylinder, an operation of obtaining a target operating angle of the plurality of valves in one cylinder in accordance with an operation state. Angle determining means, valve opening timing changing means for changing the valve opening timings of the plurality of valves provided in one cylinder relative to each other, and opening and closing the valve timings by the valve opening timing changing means relative to each other. Operating angle control means for controlling the operating angle of the valve to the target operating angle determined by the operating angle determining means.

In this internal combustion engine, the two valves are opened and closed by changing the valve opening timing relative to each other. In this case, the period from the start of opening of the first valve to the opening of the valve which has been opened later is the substantial valve opening period of the valve, and the valve opening of the valve is substantially completed. The operating angle can be freely set.

The internal combustion engine according to the present invention may include a delay amount determining means for calculating a relative delay amount of the valve opening timing based on the target operating angle determined by the operating angle determining means. .

In the internal combustion engine of the present invention, the plurality of valves provided in one cylinder may be constituted by electromagnetically driven valves which are opened and closed by using electromagnetic force.

[0010] In the internal combustion engine of the present invention, the valve opening timing changing means can relatively change the valve opening timing of the valve only when the target operating angle is less than a predetermined value.

In the internal combustion engine of the present invention, the plurality of valves, which relatively change the valve opening timing by the valve opening timing changing means, are shifted to the valve closing operation immediately before reaching the fully open position by the valve opening operation. Operation can be controlled. In this way, a small operating angle, which could not be set as a practical operating angle, can be set as a practical operating angle.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an internal combustion engine having a variable valve mechanism according to the present invention will be described below with reference to FIGS. The embodiments described below are embodiments in which the present invention is applied to a gasoline engine for driving a vehicle as an internal combustion engine.

FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine and an intake / exhaust system thereof according to the present embodiment. The internal combustion engine shown in FIG. 1 is a lean-burnable water-cooled 4-cylinder 4-cycle gasoline engine 1.

The engine 1 includes a cylinder block 1b in which four cylinders 21 and a cooling water passage 1c are formed, and a cylinder head 1 fixed on an upper portion of the cylinder block 1b.
a.

A crankshaft 23 as an engine output shaft is rotatably supported on the cylinder block 1b.
This crankshaft 23 is connected to the connecting rod 1
9 is connected to a piston 22 slidably mounted in each cylinder 21.

Above the piston 22 of each cylinder 21, a combustion chamber 24 surrounded by the top surface of the piston 22 and the wall surface of the cylinder head 1a is formed. The cylinder head 1a has an ignition plug 2 facing the combustion chamber 24 of each cylinder 21.
5 is attached, and the spark plug 25 is
An igniter 25a for applying a drive current to the power supply is electrically connected.

In the cylinder head 1a, each cylinder 2
Two open ends of the intake port 26 and two open ends of the exhaust port 27 are formed at a portion facing one combustion chamber 24. And the cylinder head 1
At a, an intake valve 28 that opens and closes each open end of the intake port 26 and an exhaust valve 29 that opens and closes each open end of the exhaust port 27 are movably mounted.

The cylinder head 1a is provided with an electromagnetic drive mechanism 30 (hereinafter referred to as an intake-side electromagnetic drive mechanism 30) for driving the intake valve 28 forward and backward by using an electromagnetic force generated when an exciting current is applied. The same number of intake valves 28 are provided. Each intake-side electromagnetic drive mechanism 30 is electrically connected to a drive circuit 30a (hereinafter, referred to as an intake-side drive circuit 30a) for applying an exciting current to the intake-side electromagnetic drive 30.

An electromagnetic drive mechanism 31 (hereinafter referred to as an exhaust-side electromagnetic drive mechanism 31) for driving the exhaust valve 29 forward and backward using an electromagnetic force generated when an exciting current is applied to the cylinder head 1a. ) Are provided in the same number as the exhaust valves 29. Each exhaust-side electromagnetic drive mechanism 31 is electrically connected to a drive circuit 31a (hereinafter, referred to as an exhaust-side electromagnetic drive mechanism 31) for applying an exciting current to the exhaust-side electromagnetic drive mechanism 31.

That is, the intake valve 28 and the exhaust valve 29 are electromagnetically driven valves. The configurations of the intake-side electromagnetic drive mechanism 30 and the exhaust-side electromagnetic drive mechanism 31 will be described later in detail.

The cylinder head 1a of the engine 1 has 4
An intake manifold 33 having two branch pipes is connected, and the intake port 26 of each cylinder 21 is connected to each branch pipe of the intake manifold 33. In the cylinder head 1a, a fuel injection valve 32 is mounted near a connection portion with the intake manifold 33 with its injection hole facing the intake port 26.

The intake manifold 33 is connected to a surge tank 34 for suppressing pulsation of intake air. The surge tank 34 is connected via an intake pipe 35 to an air cleaner box 36 for removing dust and dirt from the intake air.

An air flow meter 44 for outputting an electric signal corresponding to the mass of air flowing through the intake pipe 35 (mass of intake air) is attached to the intake pipe 35. Downstream of the air flow meter 44 in the intake pipe 35,
A throttle valve 39 for adjusting the flow rate of intake air flowing through the intake pipe 35 is provided.

The throttle valve 39 includes a stepper motor or the like, and a throttle actuator 40 for opening and closing the throttle valve 39 in accordance with the magnitude of the applied power, and a throttle for outputting an electric signal corresponding to the opening of the throttle valve 39. A position sensor 41 and an accelerator position sensor 43 that is mechanically connected to the accelerator pedal 42 and that outputs an electric signal corresponding to the operation amount of the accelerator pedal 42 are attached.

On the other hand, an exhaust manifold 45 having four branch pipes is connected to the cylinder head 1a of the engine 1, and each branch pipe of the exhaust manifold 45 is connected to the exhaust port 27 of each cylinder 21. I have.

The exhaust manifold 45 is provided with the exhaust purification catalyst 4
The casing 46 is connected to a casing 46 that houses the casing 6a. The casing 46 is connected to a muffler (not shown) via an exhaust pipe 47.

Here, as the exhaust purification catalyst 46a, for example, a three-way catalyst, a storage reduction type NOx catalyst, a selective reduction type N
An Ox catalyst or a catalyst obtained by appropriately combining these various catalysts can be used. The three-way catalyst refers to HC, C contained in the exhaust gas when the air-fuel ratio of the exhaust gas flowing into the catalyst is a predetermined air-fuel ratio near the stoichiometric air-fuel ratio.
Oxidation-reduction type NOx catalyst is a catalyst that purifies O and NOx. NOx contained in exhaust gas when the air-fuel ratio of exhaust gas flowing into the catalyst is leaner than the stoichiometric air-fuel ratio
The occluded, the air-fuel ratio of the inflowing exhaust gas was absorbed in the time equal to the stoichiometric air-fuel ratio or richer than that NOx released, a catalyst for reducing the N _2, is a selective reduction type NOx catalyst, the oxygen A catalyst that reduces or decomposes NOx in the presence of hydrocarbons in an excess atmosphere.

Here, the air-fuel ratio of the exhaust gas refers to the exhaust passage upstream of the exhaust purification catalyst 46a, the engine combustion chamber,
It means the ratio of the total amount of air supplied to the intake passage or the like to the total amount of fuel (hydrocarbon). Therefore, when no fuel, reducing agent or air is supplied into the exhaust passage upstream of the exhaust purification catalyst 46a, the air-fuel ratio of the exhaust gas matches the air-fuel ratio of the air-fuel mixture supplied into the engine combustion chamber.

In the collecting pipe of the exhaust manifold 45,
An air-fuel ratio sensor 48 that outputs an electric signal corresponding to the air-fuel ratio of the exhaust gas flowing in the exhaust manifold 45, in other words, the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst 46a.
Is attached.

An exhaust temperature sensor 49 for outputting an electric signal corresponding to the temperature of the exhaust gas flowing out of the exhaust purification catalyst 46a is attached to a portion of the exhaust pipe 47 located immediately downstream of the exhaust purification catalyst 46a. In this embodiment, the exhaust gas temperature detected by the exhaust temperature sensor 49 is used as the catalyst bed temperature of the exhaust purification catalyst 46a.

The engine 1 includes a crankshaft 2
3, a crank position sensor 51 including a timing rotor 51a attached to an end of the engine 3 and an electromagnetic pickup 51b attached to a cylinder block 1b near the timing rotor 51a, and cooling flowing through a cooling water passage 1c formed inside the engine 1. A water temperature sensor 52 attached to the cylinder block 1b to detect the temperature of water is provided.

Here, the aforementioned intake side electromagnetic drive mechanism 30
The exhaust-side electromagnetic drive mechanism 31 will be described. still,
Since the intake-side electromagnetic drive mechanism 30 and the exhaust-side electromagnetic drive mechanism 31 have the same configuration, the exhaust-side electromagnetic drive mechanism 31 will be described as an example, and the description of the intake-side electromagnetic drive mechanism 30 will be omitted.

FIG. 2 is a sectional view showing the structure of the exhaust-side electromagnetic drive mechanism 31. In FIG. 2, a cylinder head 1a of the engine 1 includes a lower head 10 fixed to an upper surface of a cylinder block 1b, and an upper head 11 provided on an upper portion of the lower head 10.

The lower head 10 is provided with the two exhaust ports 27 described above for each cylinder 21, and the exhaust valve 2 described above is provided at the open end of each exhaust port 27 on the combustion chamber 24 side.
The valve seat 12 for the seating of the nine valve bodies 29a is provided.

The lower head 10 has a through hole having a circular cross section penetrating from the inner wall surface of each exhaust port 27 to the upper surface of the lower head 10, and a cylindrical valve guide 13 is inserted and fixed in the through hole. . In the valve guide 13,
A valve shaft 29b of the exhaust valve 29 penetrates so as to be able to advance and retreat in the axial direction.

A core mounting hole 14 having a circular cross section is provided in the upper head 11 concentrically with the valve guide 13.
The core mounting hole 14 has a large-diameter portion 14 b having a large hole diameter at a portion facing the lower head 10.
a small-diameter portion 14 having a smaller hole diameter than the large-diameter portion 14b above b
a are connected.

An annular first core 301 and a second core 302 made of a soft magnetic material are fitted in the small diameter portion 14a in series in the axial direction with a predetermined gap 303 therebetween. At the upper end of the first core 301 and the lower end of the second core 302,
A flange 301a or a flange 302a is formed.
2 are inserted into the core mounting holes 14 from below, and the first core 301 is formed by the flange 301a and the flange 302a contacting the upper edge or the lower edge of the small diameter portion 14a.
And the second core 302 is positioned, and the gap 303
Is maintained at a predetermined distance.

Above the first core 301, a cylindrical upper cap 305 is attached. The upper cap 305 has a flange 305 formed at the lower end thereof.
a is fixed to the upper surface of the upper head 11 by passing a bolt 304 through it. Here, the lower end of the upper cap 305 including the flange portion 305a is fixed in a state of being in contact with the peripheral edge of the upper surface of the first core 301, whereby the first core 301 is fixed to the upper head 11.

On the other hand, a lower cap 307 made of an annular body having an outer diameter substantially the same as that of the large diameter portion 14b of the core mounting hole 14 is attached to a lower portion of the second core 302. The lower cap 307 is fixed by a bolt 306 to a step surface formed at a boundary between the small diameter portion 14a and the large diameter portion 14b. Here, the lower cap 307 is connected to the second core 30.
The second core 302 is fixed to the upper head 11 in a state in which it abuts on the lower peripheral edge of the second core 302.

A first electromagnetic coil 308 is mounted on a groove formed on the end face of the first core 301 on the gap 303 side, and a groove formed on an end face of the second core 302 on the gap 303 side is provided. The second electromagnetic coil 309 is mounted. The first electromagnetic coil 308 and the second electromagnetic coil 309 are arranged to face each other with a gap 303 interposed therebetween, and the first and second electromagnetic coils 308 and 309 are electrically connected to the exhaust-side drive circuit 31a, respectively. Connected.

In the gap 303, an armature 311 made of a disk-shaped soft magnetic material having an outer diameter smaller than the inner diameter of the gap 303 is arranged. An armature shaft 310 is fixed through the center of the armature 311. The upper half of this armature shaft 310 is the first
The upper portion of the core 301 penetrates through the hollow portion of the core 301 so as to project into the upper cap 305, and the lower half of the core 301 penetrates through the hollow portion of the second core 302 so that the lower end projects into the large-diameter portion 14b. The first core 301 and the second core 302 are held movably in the axial direction.

A disc-shaped upper retainer 312 is fixed to the upper end of the armature shaft 310 protruding into the upper cap 305, and an adjust bolt 313 is screwed into the upper opening of the upper cap 305. . These applique retainer 312 and adjust bolt 3
An upper spring 314 is interposed between the adjusting bolt 313 and a spring seat 315 between the adjusting bolt 313 and the armature shaft 310 and the armature 311 by the upper spring 314. (Ie, downward in FIG. 2).

On the other hand, the upper end of the valve shaft 29b of the exhaust valve 29 abuts against the lower end of the armature shaft 310 projecting into the large diameter portion 14b. A disc-shaped lower retainer 29c is fixed to the upper end of the valve shaft 29b,
A lower spring 316 is sandwiched between the lower retainer 29c and the lower head 10, and the lower spring 316 urges the exhaust valve 29 in a valve closing direction (that is, upward in FIG. 2). As a result, the upper end of the valve shaft 29b of the exhaust valve 29 abuts on the lower end of the armature shaft 310, and moves the armature shaft 310 and the armature 311 away from the large diameter portion 14b of the core mounting hole 14 (ie, upward in FIG. 2). Energize.

In the exhaust-side electromagnetic drive mechanism 31 configured as described above, when no exciting current is applied to the first electromagnetic coil 308 and the second electromagnetic coil 309 from the exhaust-side drive circuit 31a, the armature 311, the upper spring 314 biases the armature 311 downward (that is, the direction in which the exhaust valve 29 is opened), and the lower spring 316 raises the armature 311 upward (that is, the direction in which the exhaust valve 29 is closed). The armature 311 is elastically supported at a position where these urging forces are balanced, and is maintained in a neutral state.

The biasing force of the upper spring 314 and the lower spring 316 is set so that the neutral position of the armature 311 coincides with the intermediate position between the first core 301 and the second core 302 in the gap 303. When the neutral position of the armature 311 is deviated from the above-described intermediate position due to an initial tolerance of components, aging, etc., it is possible to adjust the neutral position of the armature 311 with the adjust bolt 313 so as to match the above-described intermediate position. Has become.

The length of the armature shaft 310 and the valve shaft 29b in the axial direction is determined by the distance between the armature 311 and the gap 30.
3, the valve body 29a is set to an intermediate position between the fully open side displacement end and the fully closed side displacement end (hereinafter, referred to as a middle open position).

In the exhaust-side electromagnetic drive mechanism 31 configured as described above, when an excitation current is applied to the first electromagnetic coil 308 from the exhaust-side drive circuit 31a, the first core 30
Between the first electromagnetic coil 308 and the armature 311, an electromagnetic force is generated in a direction for displacing the armature 311 toward the first core 301, and the second electromagnetic force is generated from the exhaust-side drive circuit 31 a.
When an exciting current is applied to the electromagnetic coil 309 of
An armature 311 is provided between the second core 302, the second electromagnetic coil 309, and the armature 311.
An electromagnetic force is generated in the direction of displacing to the side.

Therefore, the exhaust side electromagnetic drive mechanism 31
Then, the armature 311 and the armature shaft 310 move forward and backward by alternately applying the exciting current from the exhaust-side drive circuit 31a to the first electromagnetic coil 308 and the second electromagnetic coil 309, and the valve is synchronized with the operation. Shaft 29b
Is driven forward and backward, and as a result, the valve body 29a is driven to open and close.

At this time, the first electromagnetic coil 308 and the second
By changing the timing of applying the exciting current to the electromagnetic coil 309 and the magnitude of the exciting current, the exhaust valve 29
Opening / closing timing can be controlled.

The exhaust-side electromagnetic drive mechanism 31 includes:
Valve lift sensor 317 for detecting displacement of exhaust valve 29
Is attached. This valve lift sensor 317
Is composed of a disk-shaped target 317a attached to the upper surface of the applicator 312, and a gap sensor 317b attached to a part of the adjustment bolt 313 facing the above-mentioned retainer 312.

In the valve lift sensor 317 thus configured, the target 317a is displaced integrally with the armature 311 and the gap sensor 317b outputs an electric signal corresponding to the distance between the gap sensor 317b and the target 317a.

At this time, the output signal value of the gap sensor 317b when the armature 311 is in the neutral state is stored in advance, and the deviation between the output signal value and the current output signal value of the gap sensor 317b is calculated. Thus, the displacement of the armature 311 and the exhaust valve 29 can be specified.

The engine 1 has an electronic control unit (Electronic Control Unit) for controlling the operation state of the engine 1.
A control unit (ECU) 20 is also provided. ECU2
Numeral 0 denotes a digital computer, and CPUs interconnected by a bidirectional bus 400 as shown in FIG.
(Central processor unit) 401, ROM (read only memory) 402, RAM (random access memory) 403, input port 405, output port 406
A / A connected to the input port 405
A D converter (A / D) 407 is provided.

An analog port output from the throttle position sensor 41, the accelerator cell sensor 43, the air flow meter 44, the air-fuel ratio sensor 48, the exhaust temperature sensor 49, the water temperature sensor 52, the valve lift sensor 317, etc. is provided to the input port 405 of the ECU 20. Signal is A / D converter 4
07 is converted into a digital signal and input. The digital signal output from the crank position sensor 51 is directly input to the input port 405 of the ECU 20.

The output port 406 of the ECU 20 includes the igniter 25a, the intake side drive circuit 30a, and the exhaust side drive circuit 3
1a, fuel injection valve 32, throttle actuator 4
0 and the like.

The ROM 402 of the ECU 20 stores a fuel injection amount control routine for determining a fuel injection amount, a fuel injection timing control routine for determining a fuel injection timing, and an ignition timing of the ignition plug 25 of each cylinder 21. , The throttle opening control routine for determining the opening of the throttle valve 39, the intake valve opening / closing timing control for determining the opening / closing timing of the intake valve 28, and the opening / closing timing of the exhaust valve 29. Valve opening / closing timing control routine for determining the amount of excitation current to be applied to the intake-side electromagnetic drive mechanism 30, and determining the amount of excitation current to be applied to the exhaust-side electromagnetic drive mechanism 31 In this embodiment, in addition to application programs such as an exhaust-side excitation current amount control routine for Stores small operating angle control routine that predicate.

The ROM 402 of the ECU 20 stores various control maps in addition to the above-described application programs. For example, a fuel injection amount control map showing the relationship between the operating state of the engine 1 and the fuel injection amount, a fuel injection timing control map showing the relationship between the operating state of the engine 1 and the fuel injection timing, the operating state of the engine 1 and each ignition Stopper 2
5, an ignition timing control map showing the relationship between the ignition timing of the engine 5, the throttle opening control map showing the relationship between the operating state of the engine 1 and the opening of the throttle valve 39, the operating state of the engine 1 and the opening timing of the intake valve 28 , An intake valve opening angle control map showing the relationship between the operating state of the engine 1 and the opening period (duration) of the intake valve 28, the operating state of the engine 1 and the exhaust valve An exhaust valve opening timing control map showing the relationship between the opening timing of the exhaust valve 29, the exhaust valve working angle control map showing the relationship between the operating state of the engine 1 and the opening period of the exhaust valve 29, the operating state of the engine 1, and the intake air An excitation current amount control map or the like showing a relationship with an excitation current amount to be applied to the side electromagnetic drive mechanism 30 and the exhaust side electromagnetic drive mechanism 31.

The RAM 403 stores output signals of each sensor and C
The calculation result of the PU 401 is stored. The calculation result is:
For example, it is an engine speed calculated based on an output signal of the crank position sensor 51 or the like. Various data stored in the RAM 403 is rewritten to the latest data every time the crank position sensor 51 outputs a signal.

The backup RAM 45 is a non-volatile memory that retains data even after the operation of the engine 1 is stopped, and stores learning values related to various controls. CPU 401
Operates according to an application program stored in the ROM 402, and executes fuel injection control, ignition control, throttle control, small operating angle control, and the like.

At this time, the CPU 401 determines the operating state of the engine 1 using output signal values of the crank position sensor 51, the accelerator position sensor 43, the air flow meter 44, and the like as parameters, and various types of operation are performed in accordance with the determined operating state. Execute control.

For example, when the CPU 401 determines that the operating state of the engine 1 is in the low-to-medium load operation range, the CPU 401 performs lean combustion operation using an air-fuel mixture in an excess oxygen state (air-fuel mixture with a lean air-fuel ratio). The throttle opening, fuel injection amount, opening / closing timing of the intake valve 28, opening / closing timing of the exhaust valve 29, and ignition timing are controlled.

If it is determined that the operating state of the engine 1 is in the high load operation range, the CPU 401 determines the throttle opening, fuel, and the like to realize stoichiometric operation with a stoichiometric mixture (stoichiometric mixture). Injection amount, intake valve 28
, The opening / closing timing of the exhaust valve 29, and the ignition timing.

Next, the operation angle control of the intake valve 28 and the exhaust valve 29 in this internal combustion engine will be described. Since the operating angle control method for the intake valve 28 and the exhaust valve 29 is the same, the operation angle control of the exhaust valve 29 will be described as an example, and the description of the operation angle control of the intake valve 28 will be omitted.

When the exhaust valve 29 is fully closed, the armature 311 of the exhaust-side electromagnetic drive mechanism 31 is attracted to the first core 301 by the electromagnetic force of the first electromagnetic coil 308 and magnetically attached, and the exhaust valve 29 is fully opened. In the state, the armature 311 is attracted to the second core 302 side by the electromagnetic force of the second electromagnetic coil 309, and the armature 311 is magnetically attached to the second core 302 during the fully open state holding period.

Two exhaust valves 2 provided in one cylinder 21
The valve opening period (operating angle) of the engine 9 is set in advance according to the operating state of the engine 1, and is stored in the ROM 402 of the ECU 20 as the exhaust valve operating angle control map described above.

Normally, the two exhaust valves 29 are operated in synchronization with the valve opening timing. FIG. 4 shows a valve lift curve when both exhaust valves 29 are operated in synchronization. In this case, the operating angle θ of the exhaust valve 29 is equal to the closing / opening movement time t from when the exhaust valve 29 changes from the fully closed state to the fully opened state.
_1, fully opened holding time t ₂ for holding the fully open state is determined by the sum of the opening and closing movement time t ₃ until reaching the fully closed state from the fully open state. Since the closing and opening movement time t ₁ and the opening and closing movement time t ₃ are constant irrespective of the engine speed, when the operating angle θ of the exhaust valve 29 is changed, the fully open holding time t ₂ is changed.

In the opening operation in which the exhaust valve 29 moves from the fully closed state to the fully opened state, as shown in FIGS. 5 and 6, the valve lift is unstable immediately after reaching the fully opened state (maximum lift). There, it is necessary stabilization time T ₂ to stabilize at maximum lift. Incidentally, FIG. 5 is an enlarged view of the valve lift curve in the stabilization wait T _2. Thus the valve lift in a stable wait time T ₂ becomes unstable, because the armature 311 when the exhaust valve 29 becomes fully open, etc. bounce generated when seated on the second core 302. Thus the exhaust valve 29 starts the closing operation when in the stabilization time T _2, valve closing operation becomes unstable, the control of the working angle θ of the exhaust valve 29 becomes difficult.

On the other hand, when the fully open holding time t _{2 is set} to “0”, that is, when the exhaust valve 29 is shifted to the valve closing operation immediately before reaching the fully open position, the exhaust valve 29 is changed from the open operation to the open operation. It has been experimentally confirmed that the control can be stably performed over the closing operation. The valve opening period T _{1 in} this case is
The sum of the closing and opening movement time t ₁ and the opening and closing movement time t ₃ (T ₁ =
t ₁ + t ₃ ). Here, the valve opening period T ₁ may be that the time-converted value of the minimum working angle.

Therefore, the opening timings of both exhaust valves 29 are the same.
If the exhaust valve 29 is to be operated in
Assuming Tθ, (i) Tθ = T₁Or (ii) Tθ ≧ T₁
+ T_TwoThe exhaust valve 29 can be controlled stably in the range of
K, but T₁<Tθ <T₁+ T_TwoIn the region of the exhaust valve 29
Since stable control is difficult, the opening period of the exhaust valve 29 is set to T
₁<Tθ <T₁+ T_TwoCannot be set in the range.

Therefore, in this internal combustion engine, when the valve opening period Tθ of the exhaust valve 29 is set in the range of T ₁ <Tθ <T ₁ + T ₂ , as shown in FIG. 29 is set to be shorter than the opening timing of the first exhaust valve 29 by (Tθ−T
₁ ) and the two exhaust valves 2
9 fully open holding time t ₂ of the "0", performs control so as to shift to closed operation just prior to reaching the respective exhaust valves 29 to the full open position.

In this manner, the opening period of the exhaust valve 29
Tθ is substantially T₁<Tθ <T₁+ T _TwoSet within the range
And when set in the range, two
Both the exhaust valves 29 are stable from the opening operation to the closing operation.
Can be controlled. As a result, T₁Greater than
During the valve opening period, the exhaust valve 29 is freely and stably
Can be controlled.

Next, the operating angle control (hereinafter referred to as small operating angle control) performed by changing the valve opening timing of the two exhaust valves 29 will be described with reference to the flowchart of FIG. CPU4
In executing the small operating angle control, 01 executes a small operating angle control routine shown in FIG. This small operating angle control routine is stored in the ROM 402 of the ECU 20 in advance, and is repeatedly executed by the CPU 401 at regular intervals.

<Step 101> First, the CPU 401
In step 101, the target operating angle of the exhaust valve 29 according to the engine operating state is determined by referring to the exhaust valve operating angle control map in the ROM 402, and a time conversion value Tθ obtained by converting the target operating angle into time is determined.

<Step 102> Next, the CPU 401
Proceeds to step 102, T.theta calculated in step 101 it is determined whether or not smaller than the predetermined time T _0. Here, the predetermined time T ₀ is the sum of the time conversion value T ₁ of the minimum operating angle and the stabilization waiting time T ₂ (T ₀ = T ₁ + T ₂ ).

If a negative determination is made in step 102,
The CPU 401 ends the execution of this routine once. That is, in this case, normal control for operating the two exhaust valves 29 in synchronization with the valve opening timing is performed.

<Step 103> On the other hand, step 102
If an affirmative determination is made in step 1, the CPU 401 proceeds to step 1
Proceed to 03, seek the valve opening delay time T ₃ from the following equation. T ₃ = Tθ−T ₁

<Step 104> Next, the CPU 401
Proceeds to step 104, and executes the valve opening timing changing operation control for both exhaust valves 29. That is, the second exhaust valve 29
With the opening timing than the opening timing of the first exhaust valve 29 for controlling the opening timing to delay only the valve opening delay time T _3, both the two exhaust valves 29 is operated at the minimum working angle. After executing the valve opening timing change operation control, the CPU 401
Terminates the execution of this routine once.

In this embodiment, the CPU 401
Of the series of signal processing according to the present invention realizes the operating angle determining means by the portion for executing step 101, and
Is executed by the part that executes the step (a), and the valve opening timing changing part and the operating angle control part are realized by the part that executes the step 104.

[0079]

According to the internal combustion engine of the present invention, in an internal combustion engine in which at least one of an intake valve and an exhaust valve is provided in a plurality of cylinders, a plurality of valves are provided in one cylinder. Operating angle determining means for obtaining a target operating angle of the valve according to an operating state; valve opening timing changing means for relatively changing valve opening timings of the plurality of valve operating valves provided in one cylinder; Operating angle control means for controlling the valve operating angle to the target operating angle determined by the operating angle determining means by changing the valve opening timing of the valve relative to each other by the valve timing changing means. Accordingly, an excellent effect that the degree of freedom in setting the practical operating angle of the valve train can be increased.

Further, in the present invention, the operation control is performed so that the plurality of valves, which relatively change the valve opening timing by the valve opening timing changing means, shift to the valve closing operation immediately before reaching the fully open position by the valve opening operation. In this case, an excellent effect is obtained in that a small operating angle, which could not be set as a practical operating angle, can be set as a practical operating angle.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine according to the present invention.

FIG. 2 is a diagram showing the configuration of an exhaust valve and its electromagnetic drive mechanism.

FIG. 3 is a block diagram showing an internal configuration of an ECU.

FIG. 4 is a valve lift curve (1) of an exhaust valve.

FIG. 5 is a valve lift curve (2) of an exhaust valve.

FIG. 6 is a valve lift curve showing the stability waiting time portion in an enlarged manner.

FIG. 7 is a valve lift curve of an intake / exhaust valve during execution of a valve opening timing change operation control.

FIG. 8 is a flowchart illustrating a valve opening timing change operation control routine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine (internal combustion engine) 20 ECU 22 Piston 28 Intake valve (valve drive, electromagnetic drive valve) 29 Exhaust valve (valve drive, electromagnetic drive valve) 30 Intake side electromagnetic drive mechanism 31 Exhaust side electromagnetic drive mechanism 30a Intake side drive circuit 31a Exhaust side drive circuit

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshihiro Iwashita 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Kazuhiko 1 Toyota Motor Town Toyota City, Aichi Prefecture Inside Toyota Motor Corporation ( 72) Inventor Masashi Katsumada 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Masato Ogiso 1 Toyota Town Toyota City, Toyota City Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Hideyuki Nishida Aichi Prefecture 1 Toyota Town, Toyota City Toyota Motor Corporation (72) Inventor Tomomi Yamada 1 Toyota Town Toyota City, Aichi Prefecture Toyota Motor Corporation F-term (reference) 3G018 AB09 BA38 DA24 DA36 DA41 DA66 DA83 EA02 EA11 EA13 EA14 EA16 EA17 EA32 EA33 EA35 FA01 FA07 FA08 GA02 3G092 AA01 AA09 AA11 BB01 BB06 DA01 DA02 DA03 DC03 DG08 EA06 EA07 EA16 EA17 EC01 EC05 EC09 GA05 GA06 HA01Z HA06X HA06Z HA13X HA13Z HD01Z HD02Z HD05X HE01Z HE03Z HE08Z HF08Z 3G301 HA01 HA09 HA15 HA19 KA08 KA09 LA03 LA07 LC01 LC04 LC10 MA11 MA18 PE02 NE11 PD12 NE11 PD11 PE10A PE10Z PF03Z

Claims (5)

[Claims] In an internal combustion engine in which at least one of an intake valve and an exhaust valve is provided in a plurality of cylinders in one cylinder, a target operating angle of the plurality of valves in one cylinder is set to an operating state. Operating angle determining means determined in accordance with the following: valve opening timing changing means for relatively changing the valve opening timings of the plurality of valve operating valves provided in one cylinder; and opening of the valve operating means by the valve opening timing changing means. An internal combustion engine comprising: operating angle control means for controlling the operating angle of the valve to the target operating angle determined by the operating angle determining means by changing the valve timings relative to each other. 2. The apparatus according to claim 1, further comprising delay amount determining means for calculating a relative delay amount of the valve opening timing based on the target operating angle obtained by the operating angle determining means. An internal combustion engine as described. 3. The internal combustion engine according to claim 1, wherein the plurality of valves provided in one cylinder are constituted by electromagnetically driven valves that are opened and closed using electromagnetic force. 4. The internal combustion engine according to claim 3, wherein the valve opening timing changing means relatively changes the valve opening timing of the valve only when the target operating angle is less than a predetermined value. 5. The operation of the plurality of valves, which relatively change the valve opening timing by the valve opening timing changing means, is performed so as to shift to a valve closing operation immediately before the valve opening operation reaches a fully open position. The internal combustion engine according to claim 4, characterized in that: