JP2001289078A - Internal combustion engine with solenoid driven valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine capable of providing an appropriate feeling of slowing down even in a non-throttle state by making the generated quantity of slowing-down torque adjustable according to accelerator opening and engine speed. SOLUTION: This internal combustion engine comprises solenoid driven type valve systems 30, 31 for driving intake and exhaust valves 28, 29 to open/ close by magnetic force, and a control mechanism for controlling the intake and exhaust valves 28, 29. The internal combustion engine is provided with a means for determining whether engine speed to accelerator opening is the engine speed of fuel cut-off critical torque or less; a means for stopping the supply of fuel to the internal combustion engine 1 in the case of fuel cut-off critical torque or less, a means of computing target slowing-down torque on the basis of at least the value of the engine speed to the accelerator opening; and a means for changing the opening/closing timing or/and lift quantity of the intake and exhaust valves 28, 29 so as to coincide with the computed slowing-down torque. Further, the cycle number of one cylinder 21 or more is reduced to generate pumping loss in the compression stroke of air in the cylinder 21.

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 provided with an electromagnetically driven valve, and more particularly to an engine capable of adjusting a deceleration torque during deceleration.

[0002]

2. Description of the Related Art In order to improve fuel efficiency by reducing engine loss, the internal combustion engine may be made non-throttle. However, in such an internal combustion engine, pumping loss hardly occurs and engine braking is weakened. There's a problem.

[0003] To solve this, Japanese Patent Laid-Open No. Hei 10-331
In the control method of the internal combustion engine described in Japanese Patent No. 671, a pumping loss is effectively generated by using a variable valve mechanism capable of arbitrarily controlling the opening / closing timing of an intake valve and an exhaust valve and the lift amount thereof, thereby decelerating the vehicle. It is disclosed to assist the braking force at the time. In this control method, the brake pedal force and the like are detected, and the lift amount of the intake valve or the opening / closing timing of the intake / exhaust valve is changed in accordance with the brake operation amount.

[0004]

However, the conventional control described above generates an engine brake of a predetermined strength when a brake operation is performed during running of the vehicle, thereby realizing the assist of the braking force. Only. In other words, when the driver operates the accelerator to reduce the opening,
It does not make the driver feel the deceleration by the engine brake.

That is, in an internal combustion engine equipped with a throttle valve, the opening of the throttle valve decreases when the accelerator opening is reduced during traveling, and the internal pressure of the internal combustion engine becomes negative when the internal combustion engine reaches a predetermined rotational speed. become. Therefore, the action of the engine brake caused by the pumping loss occurred, and the operator could have a feeling of deceleration. Therefore, it is desirable that the same feeling is provided to the driver even in a non-throttle internal combustion engine.

On the other hand, even when the throttle valve is kept open and the non-throttle operation is performed despite the presence of the throttle valve in the internal combustion engine, the above-described engine brake does not act and the deceleration is felt. A situation arises in which you cannot obtain

The present invention has been made in view of such circumstances, and it is possible to adjust the amount of deceleration torque generated according to the accelerator opening and the engine speed so that a proper deceleration feeling can be obtained even in a non-throttle state. An internal combustion engine is provided.

[0008]

To solve the above problems, the present invention employs the following means. In other words, an engine that includes an electromagnetically driven valve operating mechanism that opens and closes intake and exhaust valves by magnetic force and a control mechanism that controls the intake and exhaust valves, wherein the engine speed with respect to the accelerator opening is equal to or less than the fuel cut critical torque Means for determining whether or not the engine speed, a means for stopping the supply of fuel to the internal combustion engine when the fuel cut critical torque or less, and a target deceleration torque at least by the value of the engine speed with respect to the accelerator opening degree It is characterized by comprising a calculating means, and a means for changing the opening / closing timing of the intake / exhaust valve and / or the lift amount so as to match the calculated deceleration torque.

In the control device for an internal combustion engine configured as described above, the non-throttle state, that is, the absence of the throttle valve or the presence of the throttle valve, the engine speed with respect to the accelerator opening becomes the fail-cut critical torque. In the following cases, the supply of fuel to the internal combustion engine is stopped. Then, a target deceleration torque is calculated from the accelerator opening and the engine speed, and a pumping loss is generated in the internal combustion engine by changing the opening / closing timing of the intake / exhaust valves and / or the lift amount, thereby adjusting the deceleration torque. . At this time, the effect of the engine brake occurs, so that the driver can have a feeling of deceleration.

When the driver wants to increase the engine speed, such as when accelerating the vehicle, or when a large torque is required, the driver depresses the accelerator pedal to increase the accelerator opening.
Conversely, when a large torque is not required, such as when driving at a constant speed or when decelerating, the accelerator pedal is reduced or the pedal is not depressed, so the accelerator opening is reduced or the accelerator opening is zero. Becomes

Therefore, the engine speed at which the engine speed with respect to the accelerator opening is equal to or lower than the fuel cut critical torque is a fuel whose engine speed is higher than a predetermined value and which is determined based on the accelerator opening. It refers to the case where the rotation speed is equal to or higher than the critical rotation speed. This also means that the generated torque of the internal combustion engine is equal to or less than the critical fuel cut torque determined based on the accelerator opening and the engine speed.

According to the present invention, the number of cycles of one or more cylinders can be reduced. There is at least one compression stroke of air in the cylinder in the reduced cycle. By doing so, the number of times of air compression in the cylinder increases, and control can be performed so that pumping loss increases. Therefore, the change in the pumping loss can be further increased, and the amount of generation of the deceleration torque of the internal combustion engine can be easily adjusted.

Specifically, in the case of a four-cylinder, four-cycle internal combustion engine, two-cycle operation can be exemplified in at least one cylinder, but the number of cylinders and the number of cycles are not limited. Further, the control for reducing the number of cycles and the control of the opening / closing timing of the intake / exhaust valve can be implemented in combination as much as possible.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A control device for an internal combustion engine according to the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine having an electromagnetically driven valve according to the present invention. The internal combustion engine 1 shown in FIG. 1 is a four-cycle gasoline engine including four cylinders 21 and two intake valves 28 and two exhaust valves 29 in each cylinder 21.

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

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

Above the piston 22, a piston 2
2 and a combustion chamber 24 surrounded by the wall surface of the cylinder head 1a. An ignition plug 25 is attached to the cylinder head 1a so as to face the combustion chamber 24.
The ignition plug 25 is connected to an igniter 25a for applying a drive current to the ignition plug 25.

In the cylinder head 1a, the open ends of the two intake ports 26 and the open ends of the two exhaust ports 27 are formed so as to face the combustion chamber 24, and the injection holes are formed so as to face the intake ports 26. A fuel injection valve 32 is attached.

Each open end of the intake port 26 is opened and closed by an intake valve 28 supported on the cylinder head 1a so as to be able to move forward and backward.
It is opened and closed by an electromagnetic drive mechanism 30 (hereinafter, referred to as an intake-side electromagnetic drive mechanism 30) provided on the cylinder head 1a.

Each open end of the exhaust port 27 is opened and closed by an exhaust valve 29 supported on the cylinder head 1a so as to be able to move forward and backward. These exhaust valves 29 are provided on the cylinder head 1a. It is opened and closed by a drive mechanism 31 (hereinafter, referred to as an exhaust-side electromagnetic drive mechanism 31).

Next, a specific configuration of the intake-side electromagnetic drive mechanism 30 and the exhaust-side electromagnetic drive mechanism 31 will be described. In addition,
Since the intake-side electromagnetic drive mechanism 30 and the exhaust-side electromagnetic drive mechanism 31 have the same configuration, only the intake-side electromagnetic drive mechanism 30 will be described as an example.

FIG. 3 is a sectional view showing the structure of the intake side electromagnetically driven valve 30. As shown in FIG. In the drawing, a cylinder head 1a of an internal combustion engine 1 includes a lower head 10 fixed to an upper surface of a cylinder block 1b, and an upper head 11 provided above the lower head 10.

An intake port 26 corresponding to each cylinder 21 is formed in the lower head 10, and a valve seat 12 on which a valve body 28 a of an intake valve 28 is seated is provided at an open end of each intake port 26 on the combustion chamber 24 side. Is provided.

The lower head 10 is formed with a through-hole having a circular cross section from the inner wall surface of each intake port 26 to the upper surface of the lower head 10. The through-hole has a valve shaft of an intake valve 28 inserted into the through-hole. A cylindrical valve guide 13 that guides 28b to be able to move forward and backward is inserted.

The upper head 11 has a core mounting hole 1 having a circular cross section into which the first core 301 and the second core 302 are fitted.
The core mounting hole 14 is located at a position where the axis of the core is the same as that of the valve guide 13. Core mounting hole 1
The lower part 4 has a large diameter lower part 14a and a lower large diameter part 14b.

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 and a flange 302a are respectively formed, the first core 301 is inserted into the core mounting hole 14 from above, and the second core 302 is inserted into the core mounting hole 14 from below, and the flange 301a and the flange 302a are fitted to the edge of the core mounting hole 14. The first core 301 and the second core 302 are positioned by contact with each other, and the gap 303 is maintained at a predetermined distance.

Further, a cylindrical upper cap 305 is provided above the first core 301, and is fixed to the upper surface of the upper head 11 by passing a bolt 304 through a flange portion 305a formed at the lower end thereof. At this time, the lower end of the upper cap 305 including the flange portion 305a abuts on the peripheral edge of the upper surface of the first core 301, and by holding this, the first core 301 is fixed to the upper head 11.

On the other hand, an annular lower cap 307 is provided below the second core 302, and a bolt 30
6 penetrates and is fixed to the downward step surface in the step portion of the small diameter portion 14a and the large diameter portion 14b. At this time, the lower cap 307 abuts on the lower peripheral edge of the first core 302 and holds the lower core 307 so that the first core 301 can move the upper head 11.
Fixed to

A first electromagnetic coil 308 is mounted in the groove formed on the surface of the first core 301 on the side of the gap 303, while the same is provided on the surface of the second core 302 on the side of the gap 303. , A second electromagnetic coil 309 is mounted thereon, and the first electromagnetic coil 308 and the second electromagnetic coil 30
9 are arranged facing each other.

In the middle of the gap 303, an annular armature 311 made of a soft magnetic material is arranged. The upper end of the armature 311 extends vertically from the center of the armature 311 to the inside of the upper cap 305 through the center of the first core 301, and the lower end of the upper core 305 of the second core 302. A columnar armature shaft 310 is provided to pass through the center and into the large-diameter portion 14b below the armature shaft 310. The armature shaft 310 is held so as to be able to advance and retreat in the axial direction.

A disc-shaped upper retainer 312 is joined to the base end of the armature shaft 310 extending into the upper cap 305, and an adjust bolt 313 is screwed into an upper opening of the upper cap 305. An upper spring 314 is interposed between the upper retainer 312 and the adjustment bolt 313. A spring seat 315 having an outer diameter substantially equal to the inner diameter of the upper cap 305 is interposed on the contact surface between the adjust bolt 313 and the upper spring 314.

On the other hand, the tip of the armature shaft 310 extending into the large diameter portion 12b is connected to the valve shaft 2 of the intake valve 28.
8b is in contact with the base end 281. This base end 28d
A disc-shaped lower retainer 28c is joined to an outer periphery of the lower head 10, and a lower spring 316 is interposed between the lower surface of the lower retainer 28c and the upper surface of the lower head 10.

In the intake-side electromagnetic drive mechanism 30 configured as described above, when no exciting current is applied to the first electromagnetic coil 308 and the second electromagnetic coil 309, the armature shaft 310 is moved downward by the upper spring 314. (Ie, the direction in which the intake valve 28 is opened) and the upward force of the intake valve 28 by the lower spring 316 (ie, the direction in which the intake valve 28 is closed) act, and as a result, The state where the armature shaft 310 and the intake valve 28 are in contact with each other and elastically supported at a predetermined position, that is, a so-called neutral state is maintained.

The biasing force of the upper spring 314 and the lower spring 316 is set such 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. You. When the neutral position of the armature 311 is deviated from the above-described intermediate position due to an initial tolerance or a secular change of the components, the neutral position of the armature 311 can be adjusted by the adjusting bolt 313 so as to match the above-described intermediate position. .

Further, the axial lengths of the armature shaft 310 and the valve shaft 28b are different from those of the armature 31.
When 1 is located at an intermediate position of the gap 303, the valve body 28a 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 above-described intake-side electromagnetic drive mechanism 30, when an exciting current is applied to the first electromagnetic coil 308, the first
Core 301, first electromagnetic coil 308, and armature 31
1, an electromagnetic force is generated in a direction to displace the armature 311 toward the first core 301, and when an exciting current is applied to the second electromagnetic coil 309, the second core 302 and the second electromagnetic An electromagnetic force is generated between the coil 309 and the armature 311 in a direction for displacing the armature 311 toward the second core 302.

Therefore, in the intake side electromagnetic drive mechanism 30,
The excitation current is alternately applied to the first electromagnetic coil 308 and the second electromagnetic coil 309, so that the armature 3
11, the valve body 28a is driven to open and close. At this time, the opening and closing timing of the intake valve 28 can be controlled by changing the excitation current application timing and the magnitude of the excitation current to the first electromagnetic coil 308 and the second electromagnetic coil 309.

Returning to FIG. 1, each intake port 26 of the internal combustion engine 1 is connected to a cylinder head 1a of the internal combustion engine 1.
Is connected to each branch pipe of the intake branch pipe 33 attached to the suction pipe. The intake branch pipe 33 is connected to a surge tank 34 for suppressing pulsation of intake air. An intake pipe 35 is connected to the surge tank 34. The intake pipe 35 is provided with an air cleaner box 36 for removing dust and dirt from the intake air.
Is connected to

The intake pipe 35 is provided with an air flow meter 44 for outputting an electric signal corresponding to the mass of the air flowing through the intake pipe 35 (mass of the intake air). In the intake pipe 35, the air flow meter 44
A throttle valve 39 for adjusting the flow rate of the intake air flowing through the intake pipe 35 is provided at a further downstream portion.

The throttle valve 39 is provided with a throttle actuator 40 comprising a stepper motor or the like for driving the opening and closing of the throttle valve 39 in accordance with the magnitude of the applied power.
And a throttle position sensor 41 that outputs an electric signal corresponding to the opening of the throttle valve 39.

A vacuum sensor 50 for outputting an electric signal corresponding to the pressure of the surge tank 34 is attached to the surge tank 34. On the other hand, each exhaust port 27 of the internal combustion engine 1 communicates with each branch pipe of the exhaust branch pipe 45 attached to the cylinder head 1a.
The exhaust branch pipe 45 is connected to an exhaust pipe 47 via an exhaust purification catalyst 46, and the exhaust pipe 47 is connected downstream to a muffler (not shown).

The exhaust branch 45 is connected to the exhaust branch 45.
The air-fuel ratio of the exhaust flowing through the inside, in other words, the exhaust purification catalyst 4
An air-fuel ratio sensor 48 that outputs an electric signal corresponding to the air-fuel ratio of the exhaust gas flowing into the exhaust gas 6 is attached.

The exhaust gas purifying catalyst 46 includes, for example, hydrocarbons (HC) contained in the exhaust gas when the air-fuel ratio of the exhaust gas flowing into the exhaust gas purifying catalyst 46 is a predetermined air-fuel ratio near the stoichiometric air-fuel ratio. Carbon oxide (CO), nitrogen oxide (NO
When the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst 46 is a lean air-fuel ratio, nitrogen oxides (NOx) contained in the exhaust gas are stored, and the air-fuel ratio of the inflowing exhaust gas is reduced. When the stoichiometric air-fuel ratio or the rich air-fuel ratio is attained, the occlusion-reduction type NOx catalyst that reduces and purifies while releasing the stored nitrogen oxides (NOx). Nitrogen oxides (NOx) in the exhaust when in a state and a predetermined reducing agent is present
This is a selective reduction type NOx catalyst for reducing and purifying NOx, or a catalyst obtained by appropriately combining the various catalysts described above.

The exhaust gas purifying catalyst 46 is provided with a catalyst temperature sensor 49 for outputting an electric signal corresponding to the bed temperature of the exhaust gas purifying catalyst 46. The internal combustion engine 1 includes a timing rotor 51a attached to an end of the crankshaft 23, and a timing rotor 51a.
A crank position sensor 5 comprising an electromagnetic pickup 51b attached to a nearby cylinder block 1b
1 and a water temperature sensor 52 attached to the cylinder block 1b to detect the temperature of cooling water flowing through a cooling water passage 1c formed inside the internal combustion engine 1.

The thus configured internal combustion engine 1 has an electronic control unit (ECU, hereinafter referred to as an ECU) for controlling the operation state of the internal combustion engine 1.
That. ) 20 are also provided.

The ECU 20 includes a throttle position sensor 41, an accelerator position sensor 43, an air flow meter 44, an air-fuel ratio sensor 48, and a catalyst temperature sensor 4.
9, various sensors such as a vacuum sensor 50, a crank position sensor 51, and a water temperature sensor 52 are connected via electric wiring, and output signals of the sensors are input to the ECU 20.

The ECU 20 is connected to drive circuits 301 and 310 of the intake-side electromagnetic drive mechanism 30 and the exhaust-side electromagnetic drive mechanism 31, respectively. Drive circuits other than these drive circuits 301 and 310 include an igniter 25
a, fuel injection valve 32, throttle actuator 40
Are connected via electric wiring, and the ECU 20 uses these igniters 2 by using output signal values of various sensors as parameters.
5a, the fuel injection valve 32, and the intake-side electromagnetic drive mechanism 30, the exhaust-side electromagnetic drive mechanism 3 via the drive circuits 301 and 310.
1 can be controlled.

Here, as shown in FIG. 3, the ECU 20 connects the CPs connected to each other by a bidirectional bus 400.
U401, ROM 402, RAM 403, backup RAM 404, external input circuit 405, and external output circuit 40
6 is provided.

The external input circuit 405 inputs the output signals of a sensor such as the crank position sensor 51 which outputs a digital signal, and transmits those output signals to the CPU 401 or the RAM 403.

The external input circuit 405 includes a throttle position sensor 41, an accelerator position sensor 43,
An output signal of a sensor that outputs a signal in the form of an analog signal, such as an air flow meter 44, an air-fuel ratio sensor 48, a catalyst temperature sensor 49, a vacuum sensor 50, and a water temperature sensor 52, is input, and the output signals are converted into digital signals. To the CPU 401 and the RAM 403.

The external output circuit 406 is connected to the CPU 4
01 is supplied to the igniter 25a.
Drive circuits 301 and 310 for the exhaust valve, the fuel injection valve 32,
And an alarm 53.

The ROM 402 includes a fuel injection amount control routine for determining the fuel injection amount, a fuel injection timing control routine for determining the fuel injection timing, and the opening of the intake valve for determining the opening timing of the intake valve 28. Valve timing control routine,
Exhaust valve opening timing control routine for determining the valve opening timing of the exhaust valve 29, ignition timing control routine for determining the ignition timing of the spark plug 25 of each cylinder 21, throttle valve 39
Excitation current control routine for determining the amount of excitation current to be applied to the intake-side electromagnetic drive mechanism 30 and the exhaust-side electromagnetic drive mechanism 31 in addition to an application program such as a throttle opening control routine for determining the opening of the vehicle. The routine stores an intake valve opening amount control routine for controlling the intake valve 28 to a desired lift amount, and an exhaust valve control routine for controlling the exhaust valve 29 to a desired lift amount.

The ROM 402 stores various control maps in addition to the application programs described above. The control map includes, for example, a fuel injection amount control map indicating a relationship between the operating state of the internal combustion engine 1 and the fuel injection amount, a fuel injection timing control map indicating a relationship between the operating state of the internal combustion engine 1 and the fuel injection timing, An intake valve opening / closing timing control map showing the relationship between the operating state of the internal combustion engine 1 and the opening / closing timing of the intake valve 28, an exhaust valve opening / closing timing control map showing the relationship between the operating state of the internal combustion engine 1 and the opening / closing timing of the exhaust valve 29, Internal combustion engine 1
Current amount control map showing the relationship between the operating state of the engine and the amount of exciting current to be applied to the intake-side electromagnetic drive mechanism 30 and the exhaust-side electromagnetic drive mechanism 31; the operating state of the internal combustion engine 1 and each ignition plug 2
And a throttle opening control map showing the relationship between the operating state of the internal combustion engine 1 and the opening of the throttle valve 39, and the like.

The RAM 403 stores an output signal of each sensor, a calculation result of the CPU 401, and the like. The calculation result is, for example, an engine speed calculated based on an output signal of the crank position sensor 51. The RAM
The various data stored in 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 internal combustion engine 1 is stopped, and stores learning values and the like for various controls. The CPU
401 operates in accordance with the application program stored in the ROM 402 to execute the intake valve opening / closing control and the exhaust valve opening / closing control, which are the gist of the present invention, in addition to fuel injection control, ignition control, and the like.

Hereinafter, control of the opening / closing timing of the intake / exhaust valve according to the first embodiment will be described. The four-cycle internal combustion engine 1 is provided with an intake valve 28 and an exhaust valve 29 for each cylinder.

When the internal combustion engine 1 is operating and the vehicle is running, the accelerator opening set by the driver operating the accelerator 42 is determined by the accelerator position sensor 4.
The electric signal is converted into an electric signal by the external circuit 3 and input to an external input circuit 405 in the ECU 20.

The number of revolutions of the internal combustion engine 1 is determined by the CPU 401 based on an output signal from the crank position sensor 51.
Is calculated. On the other hand, FIG. 4 is a diagram showing the relationship between the accelerator opening and the engine speed, and a state where no output is required for the internal combustion engine is shown as output torque = 0 in the figure. At this time, if the opening and closing timings of the intake valve 28 and the exhaust valve 29 are in a normal state, the intake air enters the combustion chamber without being throttled, so that the in-cylinder pressure during the intake stroke becomes a value close to the atmospheric pressure. When the fuel is cut in this state, the rotational speed gradually decreases due to the friction between the piston and the cylinder, the friction between the bearings, etc. (hereinafter simply referred to as friction), but the operation of the engine brake is very weak, and the driver almost feels a sense of deceleration. Absent.

However, in order to keep the engine speed constant, it is necessary to generate torque enough to overcome the friction. Therefore, if the fuel is cut at the stage of output torque = 0, a deceleration shock occurs, and the internal combustion engine rotates at a constant speed. You can't keep numbers. Therefore, the torque obtained by subtracting the output lost due to friction, that is, the torque that only keeps the engine speed constant, is defined as the illustrated torque,
The region where the indicated torque ≦ 0 was defined as a fuel cut region (indicated by hatching in the figure). If fuel cut is performed for the first time when only a torque (deceleration torque) less than the indicated torque that can maintain the constant number of rotations of the internal combustion engine is required, a smooth engine brake can be generated. Therefore, this indicated torque can be said to be a fuel cut critical torque. The deceleration torque below the fuel cut critical torque becomes larger as the accelerator opening is smaller. FIG. 5 shows the relationship between the accelerator opening and the deceleration torque.

When the indicated torque ≦ 0, the ECU 20 calculates a target deceleration torque based on a deceleration torque map (for example, a table as shown in FIG. 4) indicating the relationship between the accelerator opening and the engine speed. . This deceleration torque map is set in advance and stored in the ROM 402. By controlling the engine speed so that the calculated deceleration torque is obtained, the opening / closing timing of the intake and exhaust valves and / or the lift amount are changed.

The relationship between the opening / closing operation of the intake valve and the exhaust valve and the cylinder internal pressure will be described below. First, as shown in FIG. 6A, the exhaust valve opens at the bottom dead center (BDC), the exhaust valve is closed just before the top dead center (TDC), and the intake valve is opened near the top dead center to open the fresh air. If the intake valve is closed after a half stroke to the bottom dead center, a sufficient amount of intake air cannot be obtained as shown in FIG. Therefore, weak engine braking occurs due to low pump efficiency.

In FIG. 7A, the exhaust valve opens at the bottom dead center and the exhaust valve closes at the top dead center, while the intake valve opens at the top dead center and closes at the bottom dead center. As described above, as the piston approaches the bottom dead center, a large negative pressure is generated in the cylinder. In this case, the pump efficiency is higher than in the case shown in FIG.

Here, the control of the intake valve 28 and the exhaust valve 29 will be described with reference to FIG. FIG. 15 is a flowchart illustrating an example of a control procedure in the first embodiment of the internal combustion engine of the present invention. This flowchart is a control routine in a case where the opening / closing timing of the intake valve 28 and the exhaust valve 29 is changed to generate a negative pressure in the cylinder. This routine is repeatedly executed at predetermined time intervals after the start of the internal combustion engine. First, step (hereinafter referred to as “S”) 101
, The vehicle speed is detected to determine whether or not the vehicle is running. If the vehicle speed is 0, it is determined that the vehicle is stopped, and the process proceeds to S103, where the deceleration torque is calculated using a separate map from that used when the vehicle is in a running state.

On the other hand, if the vehicle speed is not 0, it is determined that the vehicle is traveling and the process proceeds to S102. In S102, based on the accelerator opening θ detected by the accelerator position sensor 43 and the engine speed Ne detected by the crank position sensor 51, it is determined whether or not the indicated torque ≦ 0, that is, whether or not the fuel cut critical torque ≦ 0. I do. When the indicated torque is larger than 0, this control is ended.

On the other hand, when the indicated torque is 0 or smaller, the process proceeds to S103, and the ECU 20 calculates a target deceleration torque from the engine speed Ne with respect to the accelerator opening θ. Next, in S104, the opening and closing timing of the intake valve 28 and the exhaust valve 29 is selected by the ECU 20 so that a predetermined deceleration torque is obtained. This opening / closing timing is executed through the intake / exhaust valve drive circuits 301 and 310 in S105, and this routine ends.

Next, a second embodiment of the present invention will be described. In this embodiment, when it is determined that the engine speed Ne is equal to or less than the fuel cut critical torque, fuel cut is performed to reduce the number of cycles in the cylinder. In this embodiment, the internal combustion engine 1 is normally operated in a four-cycle operation in which an intake stroke and an exhaust stroke are performed once while the crankshaft rotates twice, but this operation is referred to as a two-cycle operation.

That is, since the expansion stroke is eliminated in the cylinder after the fuel cut, the internal combustion engine of the four-cycle operation can be easily changed to the two-cycle operation. In this two-cycle operation, the intake stroke and the exhaust stroke are performed once each while the crankshaft makes one revolution. At this time, if one compression action is generated per one rotation of the crankshaft, the number of compressions is twice that in the case of the four-cycle operation.
Since pumping loss occurs during this compression, the feeling of deceleration is doubled due to the generation of a powerful engine brake.

The operation of the engine brake by changing the opening / closing timing of the intake / exhaust valve in the two-cycle operation will be described below. FIG. 8A shows a case where the intake valve is fully closed and only the exhaust valve is fully opened, and FIG. 8B shows a change in the cylinder internal pressure at that time. In this case, an intake action occurs while the piston moves from top dead center to bottom dead center, and an exhaust action occurs when the piston moves from bottom dead center to top dead center. There is almost no work.

When both the intake valve and the exhaust valve are normally fully closed, the air in the cylinder is compressed near the top dead center and expanded near the bottom dead center. And the effect of the expansion are canceled out, and the operation of the engine brake hardly occurs.

FIG. 9A shows a case where the intake valve is fully closed and only the exhaust valve is operated, and the exhaust valve is closed and opened at the top dead center while the piston moves from bottom dead center to top dead center. Show.
(B) shows that the cylinder pressure at that time is high at the top dead center and rapidly decreases before reaching the bottom dead center, and the compression action occurs only while the exhaust valve is closed. Although the time during which this compression action takes place is not long, it causes some pumping loss and therefore a moderate engine brake action.

In FIG. 10 (a), the intake valve is fully closed and only the exhaust valve is operated, and the exhaust valve is closed while the piston moves from bottom dead center to top dead center. It shows the case where it is open while moving from to the bottom dead center. (B) shows that the cylinder pressure at that time becomes considerably high at the top dead center and becomes low at the bottom dead center. The compression action occurs while the exhaust valve is closed, and this compression action causes pumping loss, resulting in strong engine braking action.

The examples shown in FIGS. 9 and 10 described above generate a pumping loss due to the compression action, and have an advantage that so-called oil rise can be prevented. Next, an example in which the exhaust valve is opened and closed around the top dead center and the bottom dead center will be described with reference to FIGS.

FIG. 11A shows a case where the intake valve is fully closed and only the exhaust valve is operated, and the exhaust valve is opened relatively long before and after the top dead center and the bottom dead center. (B)
Shows a change in the cylinder pressure, a negative pressure is generated between the top dead center and the bottom dead center, and a compression action is generated between the bottom dead center and the top dead center. Although the pumping loss occurs due to the negative pressure and the compression, the function of the engine brake occurs, but the engine brake is relatively weak because the opening time of the exhaust valve is long.

FIG. 12 (a) shows a case where the intake valve is fully closed and only the exhaust valve is operated, and the exhaust valve is opened shortly before and after the top dead center and the bottom dead center.
In (b), a negative pressure is generated between the top dead center and the bottom dead center, and a compression action is generated between the bottom dead center and the top dead center. A large pumping loss is generated by the negative pressure and the compression, and a strong engine braking action is provided.

In the above-mentioned example, the case where the intake valve is closed and only the exhaust valve is operated has been described. Conversely, the same operation occurs when the exhaust valve is closed and only the intake valve is operated. Next, control of the above-described intake valve and exhaust valve will be described based on a flowchart shown in FIG. This flowchart is a control routine for performing a two-cycle operation as described above to generate a pumping loss mainly due to a compression action, or to generate a negative pressure in a cylinder in addition to the pumping loss. This routine is repeatedly executed at predetermined time intervals after the start of the internal combustion engine. First, at step (hereinafter referred to as "S") 106, the vehicle speed is detected to determine whether or not the vehicle is running. If the vehicle speed is 0, it is determined that the vehicle is stopped, and the process proceeds to S108, where the deceleration torque is calculated using a separate map from that for the traveling state.

On the other hand, if the vehicle speed is not 0, it is determined that the vehicle is traveling and the process proceeds to S107. In S107, based on the accelerator opening θ detected by the accelerator position sensor 43 and the engine speed Ne detected by the crank position sensor 51, it is determined whether or not the indicated torque ≦ 0, that is, whether or not the fuel cut critical torque ≦ 0. to decide. When the indicated torque is larger than 0, this control is ended.

On the other hand, when the indicated torque is 0 or smaller, the process proceeds to S108, and the ECU 20 calculates a target deceleration torque from the engine speed Ne with respect to the accelerator opening θ. Next, in S109, the ECU 20 switches the operation to the two-cycle operation so as to obtain the deceleration torque, and then selects the opening / closing timing of the intake / exhaust valve. The opening / closing timing of the intake / exhaust valve is determined at S110 by the intake / exhaust valve drive circuit 30.
This routine is executed through the steps 1 and 310 and the routine ends.

The step S106 for judging whether or not the vehicle is in a running state is not always necessary in this control, and may be omitted. A third embodiment of the present invention will be described.

In this embodiment, when it is determined that the engine speed Ne is equal to or lower than the fuel cut critical torque, the lift amount of the intake valve 28 is reduced, and the intake valve during the intake stroke is reduced. 28 to reduce the opening area. In this case, the intake air amount is reduced, and the cylinder pressure becomes negative, so that a large pumping loss occurs. Therefore, the driver can have a feeling of deceleration due to the engine brake.

FIG. 14 shows the relationship between the lift amount of the intake valve 28 and the engine brake. Here, it is understood that the maximum lift amount is set to 8 mm, and the strength of the engine brake decreases as the lift amount is reduced. The operation of the lift amount of the intake valve may be performed in combination with the control of the opening / closing timing of the intake / exhaust valve during the four-cycle operation described above.

FIG. 13 shows the relationship between the lift amount of the intake valve 28 and the cylinder internal pressure. When the intake valve 28 is operated at the opening / closing timing in the normal operation state, the pressure diagram 60
This is a case where the intake valve 28 is operated by the lift 601. Since the intake valve 28 is opened near the maximum lift, the intake air flows into the cylinder without being throttled. At this time, the cylinder pressure is close to the atmospheric pressure, and pumping loss hardly occurs.

On the other hand, when the intake valve 28 is the lift 610, the amount of intake air is reduced, and the cylinder pressure becomes as shown in the pressure diagram 61. At this time, since the cylinder pressure becomes negative during the intake stroke, pumping loss occurs and engine braking occurs.

In order to change the lift amount, for example, a first electromagnetic coil 308 for applying an electromagnetic force in the valve closing direction to the valve element as described above, and an electromagnetic force in the valve opening direction for the valve element are applied. In the intake-side electromagnetic drive mechanism 30 including the second electromagnetic coil 309, the first electromagnetic coil 308 or one of the second electromagnetic coils 309 is replaced
When these electromagnetic coils are displaced, they are displaced in the valve axis direction by means such as supplying oil to an oil chamber whose volume fluctuates. Thus, the lift amount can be changed.

The control of the intake and exhaust valves will be described with reference to the flowchart shown in FIG. This flowchart is a control routine for a case where the lift amount of the intake valve is reduced and the cylinder pressure is set to a negative pressure. This routine is repeatedly executed at predetermined time intervals after the start of the internal combustion engine. First, in step (hereinafter referred to as “S”) 111, the vehicle speed is detected to determine whether or not the vehicle is running. If the vehicle speed is 0, it is determined that the vehicle has stopped, and the process ends. On the other hand, when the vehicle speed is not 0, it is determined that the vehicle is traveling, and the process proceeds to S112. This S11
2, the indicated torque ≦ 0 based on the accelerator opening θ detected by the accelerator position sensor 43 and the engine speed Ne detected by the crank position sensor 51.
It is determined whether or not fuel cut critical torque ≦ 0. When the indicated torque is larger than 0, this control is ended. On the other hand, when the indicated torque is 0 or smaller, the process proceeds to S113, and the ECU 20 calculates a target deceleration torque from the engine speed Ne with respect to the accelerator opening θ.

Next, in S114, the ECU 20 selects the lift amount of the intake valve so that the fuel injection is stopped and the deceleration torque is obtained. The control of the lift amount is executed in S115 via the drive circuits 301 and 310 of the intake and exhaust valves. When the target deceleration torque is reached, this control ends. Note that the determination in S111 can be omitted.

In the above-described embodiment of the present invention, the fuel cut is performed in the region where the indicated torque ≦ 0, so that the fuel efficiency is improved. Further, even if the fuel cut is performed, there is no deceleration shock, and the deceleration torque can be adjusted efficiently and without impairing the driving feeling.

By further increasing the deceleration torque, the operability of the vehicle can be improved.

[0088]

According to the present invention, when the engine speed is equal to or lower than the critical fuel cut torque, the supply of fuel is stopped, and the intake and exhaust are adjusted so as to match the target deceleration torque. Since the operating state of the valve is changed, it is possible to adjust the deceleration torque and improve the sense of deceleration due to ineffective engine braking.

When the number of operation cycles of the internal combustion engine is reduced, the pumping loss in the cylinder can be further increased, so that the adjustment of the deceleration torque is further facilitated, and the driver can have a more appropriate deceleration feeling. Can be.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a configuration of an intake-side electromagnetic drive mechanism.

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

FIG. 4 is a diagram illustrating a relationship between an accelerator opening and an engine speed;

FIG. 5 is a diagram showing a relationship between an accelerator opening and a deceleration torque.

6A is a diagram showing the opening / closing timing of an intake valve and an exhaust valve, and FIG. 6B is a diagram showing a change in cylinder internal pressure when the opening / closing timing is set to the opening / closing timing.

FIG. 7A is a diagram showing the opening / closing timing of an intake valve and an exhaust valve, and FIG. 7B is a diagram showing a change in the cylinder pressure when the opening / closing timing is set;

FIG. 8A is a diagram showing the opening and closing timing of the intake valve and the exhaust valve in the two-cycle operation, and FIG. 8B is a diagram showing the change in the cylinder pressure when the opening and closing timing is set;

9A is a diagram showing the opening and closing timings of the intake valve and the exhaust valve in the two-cycle operation, and FIG. 9B is a diagram showing the change in the cylinder internal pressure when the opening and closing timings are used;

10A is a diagram showing the opening / closing timing of the intake valve and the exhaust valve in the two-cycle operation, and FIG. 10B is a diagram showing a change in the cylinder pressure when the opening / closing timing is set;

11A is a diagram showing the opening and closing timing of an intake valve and an exhaust valve in a two-cycle operation, and FIG. 11B is a diagram showing a change in the cylinder pressure when the opening and closing timings are used;

12A is a diagram showing the opening and closing timings of an intake valve and an exhaust valve in a two-cycle operation, and FIG. 12B is a diagram showing a change in cylinder pressure when the opening and closing timings are used;

FIG. 13 is a diagram showing changes in the lift amount of the intake valve and the internal pressure of the cylinder.

FIG. 14 is a diagram showing the relationship between the lift amount of an intake valve and the strength of an engine brake.

FIG. 15 is a flowchart of the first embodiment.

FIG. 16 is a flowchart of the second embodiment.

FIG. 17 is a flowchart of the third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Internal combustion engine 20 ECU 28 Intake valve 29 Exhaust valve 30 Intake side electromagnetic drive mechanism 31 Exhaust side electromagnetic drive mechanism 32 Fuel injection valve 43 Accelerator position sensor 51 Crank position sensor 301 Intake valve drive circuit 303 First electromagnetic coil 304 Second Electromagnetic coil 310 Exhaust valve drive circuit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) F02D 13/06 F02D 13/06 F 17/02 17/02 V 41/04 330 41/04 330G 41/12 330 41/12 330 J F term (reference) 3G018 AB09 AB16 CA12 DA35 DA36 DA38 DA39 DA40 DA41 EA09 EA12 FA01 FA06 FA07 GA12 3G092 AA01 AA11 DA01 DA02 DA07 DA12 DA15 DC01 DG09 EA11 FA03 FA34 GA13 GB08 HA09Z HA13Z HB01ZHF11Z HA01 HA19 JA03 KA16 KA23 KA26 LA01 LA07 LB01 MA11 NE06 PA11Z PA14Z PE01Z

Claims (2)

[Claims] An electromagnetically driven valve mechanism for opening and closing an intake / exhaust valve by a magnetic force, and a control mechanism for controlling the intake / exhaust valve, wherein the engine speed with respect to the accelerator opening is equal to or less than a fuel cut critical torque. Means for determining whether the engine speed is equal to or less than, a means for stopping the supply of fuel to the internal combustion engine when the fuel cut critical torque or less, and a target based on at least the value of the engine speed with respect to the accelerator opening. An internal combustion engine having an electromagnetically driven valve, comprising: means for calculating a deceleration torque; and means for changing the opening / closing timing and / or lift amount of an intake / exhaust valve so as to match the calculated deceleration torque. . 2. An internal combustion engine having an electromagnetically driven valve according to claim 1, further comprising means for reducing the number of cycles of one or more cylinders.