JP3470398B2 - Valve train for internal combustion engine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve train for an internal combustion engine.

[0002]

2. Description of the Related Art An internal combustion engine in which the number of operating cylinders is changed according to the operating state of the engine has been conventionally known.
In this internal combustion engine, for example, the first cylinder and the fourth cylinder out of the four cylinders are continuously operated and the remaining second cylinder and the third cylinder are deactivated during engine low load operation, so that each of the operating cylinders The load is increased to improve engine efficiency. When the two cylinders are operated in this way and the remaining two cylinders are deactivated, that is, when the reduced cylinder operation is performed, when the intake valve and the exhaust valve of the deactivated cylinder are driven, air is sucked into the combustion chamber of the deactivated cylinder. The air is then discharged into the engine exhaust passage without being burned, and then introduced into the three-way catalyst. In this case, since the exhaust gas guided to the three-way catalyst contains a large amount of oxygen, this exhaust gas will no longer greatly deviate from the active atmosphere of the catalyst, and therefore the three-way catalyst will not be able to purify the exhaust gas well. . Further, if the intake valve is driven to suck the air in the idle cylinder, the engine pumping loss cannot be satisfactorily reduced. Therefore, there is a known valve operating system for an internal combustion engine in which an intake valve and an exhaust valve of a deactivated cylinder are held in a closed state when a cylinder which is deactivated in accordance with an engine operating state is deactivated (Japanese Patent Laid-Open No. Sho-06-26). 54-57009).

[0003]

However, when the cylinder that is made to be inactive according to the engine operating condition as in this valve operating system is made to be inactive, the intake valve and the exhaust valve of the inactive cylinder are kept in the closed state. When this is set, when the piston of the idle cylinder descends, the in-cylinder pressure in the idle cylinder decreases, which reduces the pressure acting on the piston ring, so that the piston ring is no longer held in the normal position as when operating. There is a problem that engine oil in the ring groove is scraped out toward the combustion chamber when the piston of the idle cylinder descends, so-called oil rising occurs.

[0004]

[0005]

According SUMMARY OF THE INVENTION The above SL in order to solve the problem in the first invention, the internal combustion engine so as to change the number of operating cylinders in accordance with the engine operating state, the exhaust valve driving The first cam peak and the second cam per exhaust valve on the cam
Of forming a cam mountain exhaust valve by to open the exhaust valve during the exhaust stroke Rutotomoni second cam lobes is opened during the intake stroke by the first cam nose, it should suspend the operation of the cylinders Sometimes the intake valves of the cylinders that should be stopped should be kept closed.
However, a hydraulic chamber is formed between the piston driven by the cam lobes of the cam shaft and the top of the valve stem of the exhaust valve. By controlling the hydraulic pressure in the hydraulic chambers, the higher the engine load, the higher the second cam lobes. short opening period of the exhaust valve of the operating cylinders
To such so that, at the time of engine startup is shorter than the time of idling after completion of warming up the opening period of the exhaust valve of at least operating cylinders according to the second cam lobes.

In order to solve the above problems, the second
According to the invention, in the internal combustion engine in which the number of operating cylinders is changed according to the operating state of the engine, the intake valve drive cam of the cylinder that is made to pause according to the operating state of the engine causes the intake valve to move the intake valve during the intake stroke. A first cam crest for opening the valve and a second cam crest for opening the intake valve during an explosion stroke are provided, and when the cylinder is in operation, the intake valve is opened by the first cam crest. The opening operation of the intake valve by the second cam crest is stopped, and when the cylinder is stopped, the opening operation of the intake valve by the first cam crest is stopped and the opening operation of the intake valve by the second cam crest is performed. A valve opening control means is provided to keep the exhaust valve of the cylinder closed when the cylinder is inactive. Third, to solve the above problems
According to the invention, in the internal combustion engine in which the number of operating cylinders is changed according to the operating state of the engine, the exhaust valve drive cam of the cylinder that is made to stop depending on the operating state of the engine causes the exhaust valve to move during the exhaust stroke. A first cam crest for opening the valve and a second cam crest for opening the exhaust valve during an explosion stroke are provided, and when the cylinder is in operation, the exhaust valve is opened by the first cam crest and The opening operation of the exhaust valve by the second cam crest is stopped, and when the cylinder is stopped, the opening operation of the exhaust valve by the first cam crest is stopped and the opening operation of the exhaust valve by the second cam crest is performed. A valve opening control means is provided so that the intake valve of the cylinder is kept closed when the cylinder is inactive.

[0007]

[0008]

In the first aspect of the invention, since each exhaust valve is opened by the second cam lobe during the intake stroke, the exhaust gas in the engine exhaust passage is sucked into each cylinder. EGR in operating cylinders
Gas is supplied. In the idle cylinder, the cylinder pressure is prevented from decreasing when the piston is lowered. Further , the EGR gas amount is reduced as the engine load is higher. Further , the amount of EGR gas at the time of starting the engine is smaller than that at the time of idling operation after completion of warming up, so the catalyst is heated quickly.

In the second aspect of the invention, since the intake valve of the idle cylinder is opened during the explosion stroke, air is sucked into the idle cylinder via the intake valve, so that the in-cylinder pressure is prevented from decreasing when the piston is lowered. To be done. Further, since the exhaust valve of the deactivated cylinder is kept closed, air is prevented from being discharged into the engine exhaust passage without being burned. In the third invention,
Since the exhaust valve of the idle cylinder is opened during the explosion stroke, the exhaust gas is sucked into the idle cylinder via the exhaust valve, so that the in-cylinder pressure is prevented from decreasing when the piston is lowered. Further, since the intake valve of the idle cylinder is kept closed, the air is prevented from being discharged into the engine exhaust passage without being burned.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the embodiment shown in FIG. 1, an engine body 1 has four cylinders, that is, a first cylinder 2a, a second cylinder 2b, a third cylinder 2c and a fourth cylinder 2d. Referring to FIG. 1, each cylinder 2a, 2b, 2c, 2d is connected to a common surge tank 4 via a corresponding intake branch pipe 3. A throttle valve (not shown) is arranged in the intake duct. On the other hand, each cylinder 2a, 2b, 2c, 2d is connected to a common exhaust manifold 5, and the exhaust manifold 5 is connected to a three-way catalytic converter (not shown).

In the example shown in FIG. 1, the first cylinder 2a includes a pair of intake valves 6a and a pair of exhaust valves 7a. Similarly, the second cylinder 2b has a pair of intake valves 6b and a pair of exhaust valves 7b, the third cylinder 2c also has a pair of intake valves 6c and a pair of exhaust valves 7c, and the fourth cylinder 2d also has a pair of It has an intake valve 6d and a pair of exhaust valves 7d. Intake valve 6a of first cylinder 2a and intake valve 6d of fourth cylinder 2d
Are directly driven by corresponding cams 9a and 9d, respectively, and the exhaust valve 7a of the first cylinder 2a and the fourth cylinder 2d are also driven.
The exhaust valves 7d are directly driven by the corresponding cams 10a and 10d. On the other hand, the intake valve 6b of the second cylinder 2b is connected to the cam 9 via the corresponding hydraulic device 11.
The intake valve 6c of the third cylinder 2c is driven by the cam 9c via the corresponding hydraulic device 12, and the exhaust valve 7b of the second cylinder 2b is driven by the cam 10b via the corresponding hydraulic device 13. The exhaust valve 7c of the third cylinder 2c that is driven is driven by the cam 10c via the corresponding hydraulic device 14. The intake valve driving cams 9a, 9b, 9c, 9d are formed on a common cam shaft 15, and the exhaust valve driving cams 10a, 10b,
10c and 10d are formed on a common cam shaft 16.

Next, the structure and operation of the hydraulic devices 11, 12, 13, 14 will be described. These hydraulic devices 11,
Since the structures and operations of 12, 13, and 14 are the same, only the hydraulic device 11 will be described below with reference to FIGS. 2 to 4, and the structures and operations of the other hydraulic devices 12, 13, and 14 will be described. Omit it. First, the structure of the hydraulic device 11 will be described. 2 and 3, the hydraulic device 11 includes the cam side piston 16 slidably inserted in the cam side piston insertion hole 16a. The inner wall surface of the cam side piston insertion hole 16a and the bottom surface of the cam side piston 16 define a first hydraulic chamber 17, and the first hydraulic chamber 17 is communicated with the second hydraulic chamber 18 via a communication passage 17a. The second hydraulic chamber 18 communicates with the third hydraulic chamber 21 via the first flow passage 19 and the second flow passage 20. The third hydraulic chamber 21 is defined by the inner wall surface of the valve side piston insertion hole 22 and the top surface of the valve side piston 23 slidably inserted into the valve side piston insertion hole 22. The bottom surface of the valve side piston 23 is in contact with the top surface of the stem 24 of the intake valve 6b. The intake valve 6b is engaged with the retainer 26 via the cotter 25 in the stem 24, and the retainer 26 is urged upward by the valve spring 27 in FIG. 2, that is, in the closing direction of the intake valve 6b. The lower end of the valve spring 27 is locked to a cylinder head (not shown).

A second hydraulic chamber 18 to a third hydraulic chamber 18 are provided in a first flow path 19 which connects the second hydraulic chamber 18 and the third hydraulic chamber 21 to each other.
A check valve 28 that can flow only to the hydraulic chamber 21 is provided (see FIG. 3). On the other hand, the third hydraulic chamber 2 of the second flow path 20
An annular throttle portion 29 is formed at the end on the first side.

A hydraulic oil inlet 30 and a hydraulic oil outlet 31 are formed in the second hydraulic chamber 18. As shown in FIG. 4, the hydraulic oil inlet 30 is connected to the discharge side of, for example, an engine-driven pump 33 via a pair of check valves 32b and 32c, and the suction side of the pump 33 is, for example, a cylinder head (not shown).
It is connected to an oil sump 34 formed therein. These check valves 32b and 32c can flow only from the pump 33 to the second hydraulic chamber 18. On the other hand, the hydraulic oil outlet 3
1 is connected to the oil passage between the check valve 32b and the check valve 32c via the check valve 35, the electromagnetic valve 36, and the pressure accumulating chamber 37.
The check valve 35 is allowed to flow only from the second hydraulic chamber 18 toward the solenoid valve 36, and the accumulator chamber 37 is the second hydraulic chamber 18.
It acts to temporarily store the hydraulic pressure released from. A similar hydraulic device 11 is provided for the other intake valve 6b of the pair of intake valves 6b. In the present embodiment, the check valve 32c, the solenoid valve 36, and the pressure accumulating chamber 37 form a pair of hydraulic pressures. Commonly provided for the device 11. Further, a regulator 38 is connected in the oil passage between the discharge side of the pump 33 and the check valve 32c. This regulator 38 operates oil in the oil passage between the discharge side of the pump 33 and the check valve 32c when the oil pressure in the oil passage between the discharge side of the pump 33 and the check valve 32c becomes higher than a predetermined set pressure. To escape to the oil sump 34.

Next, the operation of the hydraulic device 11 will be described. When the intake valve 6b should be opened, the solenoid valve 3
6 is closed. When the cam 9b lowers the cam side piston 16 by the cam crest, the hydraulic oil in the first hydraulic chamber 17 is discharged into the second hydraulic chamber 18 via the communication passage 17a. At this time, since the solenoid valve 36 is closed, the hydraulic pressure in the second hydraulic chamber 18 rises as the cam side piston 16 descends, and as a result, the check valve 28 in the first flow path 19 opens. ,
Thus, the hydraulic oil in the second hydraulic chamber 18 is discharged into the third hydraulic chamber 21. Since the throttle portion 29 is provided in the second flow passage 20, the flow passage area of the second flow passage 20 is made smaller than the flow passage area of the first flow passage area 19, so that the second hydraulic chamber is formed. Most of the hydraulic oil that has flowed into 18 is the first flow path 19
Through the third hydraulic chamber 21. As a result, the hydraulic pressure in the third hydraulic chamber 21 rises as the cam side piston 16 descends. The hydraulic pressure in the third hydraulic chamber 21 is the valve spring 2
When the valve closing force of valve 7 becomes larger than the valve closing force of valve 7, the valve side piston 23 descends, and thus the intake valve 6b is opened.

When the cam 9b no longer urges the cam side piston 16 downward, it moves from the second hydraulic chamber 18 to the third hydraulic chamber 2.
Since the hydraulic oil does not flow into the first hydraulic pressure chamber 1, the hydraulic pressure in the third hydraulic pressure chamber 21 does not rise. At this time, the valve side piston 23 is urged upward in FIG. 2 by the spring force of the valve spring 27 together with the intake valve 6b, and when the spring force of the valve spring 27 becomes larger than the hydraulic pressure in the third hydraulic chamber 21. The valve side piston 23 rises together with the intake valve 6b. Valve side piston 23
When the pressure rises, the hydraulic oil in the third hydraulic chamber 21
8 is discharged. A third hydraulic chamber 21 is provided in the first flow path 19.
The check valve 28 that blocks the flow of the hydraulic oil from the second hydraulic chamber 18 to the second hydraulic chamber 18 is provided, so that the hydraulic oil discharged from the third hydraulic chamber 21 passes through the second flow passage 20 to the second hydraulic chamber. Flow into. When the valve side piston 23 starts to rise,
Since the top surface of the valve-side piston 23 is located below the opening of the second flow passage 20, the hydraulic oil in the third hydraulic chamber 21 is discharged relatively quickly, so that the intake valve 6b relatively quickly. Close the valve. When the valve-side piston 23 further rises, the third hydraulic chamber 21 communicates with the second hydraulic chamber 18 via the throttle portion 29 of the second flow passage 20, so that the hydraulic oil in the third hydraulic chamber 21 relatively slowly. It is discharged to the second hydraulic chamber 18, and therefore the closing speed of the intake valve 6b is delayed. As a result, noise and vibration when the intake valve 6b is seated on the valve seat (not shown) can be reduced. The hydraulic fluid that has flowed from the third hydraulic chamber 21 into the second hydraulic chamber 18 then flows into the first hydraulic chamber 17, and therefore the hydraulic pressure within the first hydraulic chamber 17 rises, so that the cam side piston 15 moves toward the cam 9b. It will rise while following the cam surface.

On the other hand, when the opening operation of the intake valve 6b should be stopped, the solenoid valve 36 is opened. When the cam 9b lowers the cam side piston 16 due to the cam mountain, the first hydraulic chamber 1
The hydraulic oil in 7 is discharged into the second hydraulic chamber 18 via the communication passage 17. At this time, since the solenoid valve 36 is opened, the hydraulic oil is discharged from the second hydraulic chamber 18, so that the hydraulic pressure in the second hydraulic chamber 18 does not rise even if the cam-side piston 16 descends. Therefore, the hydraulic oil is not discharged from the second hydraulic chamber 18 to the third hydraulic chamber 21, so that the hydraulic pressure in the third hydraulic chamber 21 does not rise, and therefore the intake valve 6b is kept closed by the spring force of the valve spring 27. Thus, the valve opening operation of the intake valve 6b is stopped.

When the drive of the intake valve 6b should be stopped, the solenoid valve 36 is opened for the same period as the period when the intake valve 6b is opened when the solenoid valve 36 is closed. That is, the solenoid valve 36 is opened at the same time that the cam crest of the cam 9b starts to urge the cam side piston 16 downward, and the cam crest of the cam 9b stops urging the cam side piston 16 downward at the same time.
6 is closed. When the solenoid valve 36 is closed, the hydraulic oil is supplied into the second hydraulic chamber 18 via the hydraulic oil inflow hole 30, whereby the hydraulic pressure in the first hydraulic chamber 17 and the second hydraulic chamber 18 is increased. Rises. As a result, the first hydraulic chamber 17
Also, the hydraulic pressure in the second hydraulic chamber 18 can be maintained at a hydraulic pressure sufficient to open the intake valve 6b. Therefore, the solenoid valve 36 is then closed to drive the intake valve 6b, and the cam side piston 16 is closed. The first hydraulic chamber 17, the second
The intake valve 6b can be opened by increasing the pressure in the hydraulic chamber 18 and the third hydraulic chamber 21. Further, in this embodiment, the solenoid valve 36 is opened while the solenoid valve 36 is being supplied with power, so that the solenoid valve 36 is opened only while the cam crest of the cam 9b drives the cam side piston 16. By opening the valve, power consumption can be reduced.

In this embodiment, the hydraulic devices 12, 13,
14 are provided with a hydraulic circuit similar to the hydraulic circuit shown in FIG. 4, and the pair of hydraulic devices 12 includes the check valve 3
The pair of hydraulic devices 1 is connected to the pump 33 via 9a.
3 is connected to the pump 33 via the check valve 39b, and the pair of hydraulic devices 14 is connected to the pump 33 via the check valve 39c. Therefore, the pump 33 has the hydraulic devices 11, 1
It will be commonly provided for 2, 13, and 14 (see FIG. 4). Further, the hydraulic pressure of the hydraulic device 12 is the solenoid valve 40.
The hydraulic pressure of the hydraulic device 13 is controlled by the solenoid valve 41, and the hydraulic pressure of the hydraulic device 14 is controlled by the solenoid valve 42 (see FIG. 1). These solenoid valves 36, 40, 4
1, 42 are controlled by an output signal from the electronic control unit 50.

By the way, the cams 9a, 9b, 9c and 9d for driving the intake valves of the respective cylinders each have one cam lobe, and the exhaust valve 7a of the first cylinder 2a.
The cam 10a for driving the engine and the cam 10d for driving the exhaust valve 7d of the fourth cylinder 2d also have one cam lobe. On the other hand, the exhaust valve 7 of the second cylinder 2b
The cam 10b for driving b and the cam 10c for driving the exhaust valve 7c of the third cylinder 2c are each provided with two cam lobes. Next, the exhaust valve 7b of the second cylinder 2b
5 shows the structure and operation of the cam 10b for driving the vehicle.
This will be described with reference to (A) and (B). In addition, here, the hydraulic device 13 provided between the cam 10b and the exhaust valve 7b.
A case will be described in which the solenoid valve 41 that controls is always closed. Regarding the structure and operation of the cam 10c for driving the exhaust valve 7c of the third cylinder 2c, the cam 1c will be described.
Since it is similar to the operation of 0b, the description thereof will be omitted.

Referring to FIG. 5A, the cam 10b for driving the exhaust valve 7b of the second cylinder 2b has a pair of cam ridges, that is, a first cam ridge 43 and a second cam ridge 44. The angle between the apex of the first cam crest 43 and the apex of the second cam crest 44 is 113 °, for example. When the cam 10b rotates in the direction of the arrow R, the exhaust valve 7b first detects the first cam crest 43.
Thus, the valve is opened in the exhaust stroke as indicated by A in FIG. In FIG. 5B, the crank angle is 0
“°” indicates the top dead center (called the exhaust top dead center) of the second cylinder 2b at the end of the exhaust stroke. Therefore, the exhaust valve 7b is opened by the first cam crest 43 before the piston (not shown) of the second cylinder 2b reaches the exhaust bottom dead center, and is closed at a position where the piston slightly exceeds the exhaust top dead center. It On the other hand, the exhaust valve 7b is opened by the second cam crest 44 at a position where the piston exceeds the exhaust top dead center, and is closed when the piston is substantially located at the intake bottom dead center. At this time, the lift amount of the exhaust valve 7b by the second cam crest 44 is the first
The lift amount of the exhaust valve 7 by the cam crest 43 is made smaller. As shown by C in FIG. 5B, the intake valve 6b of the second cylinder 2b is opened when the piston is located slightly before the exhaust top dead center, and the piston crosses the intake bottom dead center. The valve is closed in the open position. Therefore, when the intake valve 6b is opened, the exhaust valve 7b is held in the open state by the first cam crest 43. Then, when the piston exceeds the exhaust top dead center, the exhaust valve 7b is once closed and then the exhaust gas is exhausted. The valve 7b is opened again by the second cam crest 44, and the intake valve 6b is closed after the exhaust valve 7b is closed.

The cam 10a for driving the exhaust valve 7a of the No. 1 cylinder 2a and the cam 10d for driving the exhaust valve 7d of the No. 4 cylinder 2d have the same cam peaks as the first cam peak 43 of the cam 10b. Provided, but the second of the cam 10b
The cam mountain similar to the cam mountain 44 is not provided. Therefore, for the exhaust valve 7a of the first cylinder 2a and the exhaust valve 7d of the fourth cylinder 2d, only the valve opening operation shown by A in FIG. 5B is performed.

Referring again to FIG. 1, the electronic control unit 50 comprises a digital computer and a bidirectional bus 51.
ROM (Read Only Memory) 52, RAM (Random Access Memory) 53, C interconnected via
It has a PU (microprocessor) 54, an input port 55 and an output port 56. The air flow meter 59 generates an output voltage proportional to the intake air amount, and this output voltage is input to the input port 55 via the AD converter 60. A crank angle sensor 61 that generates an output pulse each time the crankshaft rotates, for example, 30 degrees is connected to the input port 55. The CPU 54 calculates the engine speed based on this output pulse. On the other hand, the output port 56 is connected to the solenoid valves 36, 4 via the corresponding drive circuit 62.
0, 41, 42.

By the way, in the embodiment shown in FIG. 1, four cylinders 2 are operated during engine medium load operation and engine high load operation.
a, 2b, 2c, 2d are operated, and this is called full-cylinder operation. On the other hand, during engine low load operation, the first cylinder 2a and the fourth cylinder 2d are operated and the operation of the second cylinder 2b and the third cylinder 2c are stopped, which is referred to as reduced cylinder operation. The control of the number of operating cylinders in this embodiment is performed according to the map shown in FIG.
That is, when the engine load Q / N (intake air amount Q / engine speed N) during all-cylinder operation falls below a predetermined first set load L1 (arrow A in FIG. 6), the reduced cylinder Driving is performed. On the other hand, the engine load Q /
When N increases beyond the predetermined second set load L2 (arrow B in FIG. 6), the all-cylinder operation is performed. When the reduced-cylinder operation is started, the opening degree of the throttle valve (not shown) driven by the step motor is increased, so that the engine pumping loss is reduced and thus the engine efficiency can be improved. The map shown in FIG. 6 is stored in the ROM in advance.
It is stored in 53.

Next, referring to FIG. 7, each cylinder 2a, 2b, 2
A method of driving the intake valves and the exhaust valves of c and 2d will be described. In FIG. 7, a crank angle of 0 ° indicates the exhaust top dead center of each cylinder. First, FIG. 7 (A) and FIG.
Referring to (B), the second cylinder 2b is stopped during the reduced cylinder operation.
A method of driving the intake valve and the exhaust valve of the third cylinder 2c will be described. FIG. 7 (A) shows when all cylinders are in operation, that is, 2
The operation of opening the intake valves and the exhaust valves of the second cylinder 2b and the third cylinder 2c during operation of the second cylinder 2b and the third cylinder 2c is shown. When the second cylinder 2b and the third cylinder 2c are in operation, the solenoid valve 36 for controlling the hydraulic device 11 and the solenoid valve 40 for controlling the hydraulic device 12 are always closed. Therefore, in FIG. As shown, the cam 9 corresponding to the opening operation of the intake valves 6b and 6c
b and 9c respectively. On the other hand, the hydraulic system 1
The solenoid valve 41 for controlling No. 3 and the solenoid valve 42 for controlling the hydraulic device 14 are closed during the exhaust stroke, so that the exhaust valves 7b, 7c are shown in FIG. 7 by the first cam crest 43 of the corresponding cams 10b, 10c. In A), it is driven during each exhaust stroke as indicated by A1. First cam mountain 4
The valve opening operation of the exhaust valves 7b and 7c by 3 is ended, and then the second cam crest 44 starts driving the cam side piston 16, and at the same time, the solenoid valves 41 and 42 are opened, and as a result, FIG.
In (A), as indicated by B1, the valve opening operation of the exhaust valves 7b, 7c by the second cam crest 44 is stopped.

On the other hand, in the reduced cylinder operation, that is, when the second cylinder 2b and the third cylinder 2c are at rest, the solenoid valves 36,
The valve 40 is opened only during a period in which the cams 9b and 9c that drive the intake valves 6b and 6c drive the corresponding cam-side pistons 16, so that the intake valves 6b and 6c are kept closed. If the intake valves 6b and 6c are opened when the second cylinder 2b and the third cylinder 2c are deactivated, engine pumping loss cannot be reduced, and if the exhaust valves 7b and 7c are opened at this time. The air is discharged into the exhaust manifold 5 without being burned, and thus the exhaust gas cannot be satisfactorily purified by the three-way catalyst. Therefore, in this embodiment, the second cylinder 2b and the third cylinder 2
By opening the solenoid valves 36, 40 when c is stopped, the opening operation of the intake valves 6b, 6c is stopped.
As a result, engine pumping loss can be reduced, and good purification of exhaust gas in the three-way catalyst can be ensured.

By the way, the second cylinder 2b and the third cylinder 2
When the opening operation of the intake valves 6b and 6c is stopped when c is stopped, the exhaust valves 7b and 7c are driven in the same manner as when the second cylinder 2b and the third cylinder 2c are operated, that is, only by the first cam mountain 43. When the valve is opened, the exhaust valve 7b,
7c is closed a short time after the pistons of the second cylinder 2b and the third cylinder 2c start to descend, and is then kept closed while the pistons descend.
Therefore, the pressure in each combustion chamber of the second cylinder 2b and the third cylinder 2c decreases as the piston lowers, and the pressure acting on the piston ring decreases accordingly. If the piston is lowered, the engine oil in the ring groove is scraped out toward the combustion chamber, so-called oil rising occurs. Therefore, in this embodiment, the exhaust valves 7b and 7c are driven by the first cam crests 43 by keeping the solenoid valves 41 and 42 closed while the second cylinder 2b and the third cylinder 2c are at rest ( The second cam crest 44 is also driven after (A2) in FIG. 7 (B) (B2 in FIG. 7 (B)), whereby the opening period of the exhaust valves 7b, 7c during the intake stroke is the second cylinder. It is designed to be longer than when the 2b and 3rd cylinders 2c are in operation. As a result, when the pistons of the second cylinder 2b and the third cylinder 2c descend, these second cylinder 2b and the third cylinder 2c can suck the exhaust gas in the exhaust manifold 5, so that the second cylinder 2b and the third cylinder 2c. Cylinder 2
It is possible to prevent the pressure in each combustion chamber of c from decreasing and thus prevent oil rising. Further, when the exhaust valves 7b and 7c are opened during the intake stroke, the exhaust gas in the exhaust manifold 5 will be the second cylinder 2b.
Also, since the intake air is sucked into the combustion chambers of the third cylinder 2c, it is possible to reduce the temperature drop in the combustion chambers of the second cylinder 2b and the third cylinder 2c at the time of rest. As a result, good combustion in the second cylinder 2b and the third cylinder 2c can be ensured when the operation of the second cylinder 2b and the third cylinder 2c is started again. Although the engine pumping loss increases when the exhaust gas is sucked through the exhaust valves 7b and 7c as described above, the lift amount of the exhaust valves 7b and 7c by the second cam crest 44 is small, so that the engine pumping loss is reduced. The amount of increase is small.

On the other hand, the method of driving the intake valve and the exhaust valve of the first cylinder 2a and the fourth cylinder 2d is the same in all cylinder operation and in reduced cylinder operation. That is, the intake valve 6a of the first cylinder 2a and the intake valve 6d of the fourth cylinder 2d are shown in FIG.
Driven as indicated by C3 at No. 1 cylinder 2
The exhaust valve 7a of a and the exhaust valve 7d of the fourth cylinder 2d are shown in FIG.
It is driven as shown by A3 in (C).

Next, the control routine for the number of operating cylinders will be described with reference to FIGS. 8 and 9. The routine shown in FIG. 8 is executed, for example, by interruption at regular intervals. Referring to FIG. 8, at step 70, it is judged if the flag that is set when the reduced cylinder operation should be performed is set. When the flag is not set, the routine proceeds to step 71, where it is judged if the engine load Q / N is lower than the first set load L1 shown in FIG. When Q / N <L1, the routine proceeds to step 72, where the flag is set. On the other hand, in step 71, Q / N
When ≧ L1, the processing cycle ends.

When the flag is set in step 72, the process proceeds from step 70 to step 73 in the next processing cycle. In step 73, the engine load Q / N is as shown in FIG.
It is determined whether or not the load is higher than the second set load L2 shown in. When Q / N> L2, the routine proceeds to step 74, where the flag is reset. On the other hand, in step 73, Q / N ≦
When L2, the processing cycle ends.

The routine shown in FIG. 9 is executed, for example, by interruption every constant crank angle. Referring to FIG. 9, in step 80, the fuel injection action and the ignition action of the first cylinder 2a are performed. Next, at step 81, it is judged if the flag is set, that is, if it is during the reduced cylinder operation. When the flag is not set, that is, during all-cylinder operation, the routine proceeds to step 82, where the fuel injection action and ignition action of the third cylinder 2c are performed. Then, it proceeds to step 83. On the other hand, step 8
When the flag is set in 1, that is, when the reduced cylinder operation is performed, the routine jumps to step 83. Therefore, during the reduced cylinder operation, the operation of the third cylinder 2c is stopped. In step 83, the fuel injection action and the ignition action of the fourth cylinder 2d are performed. In the following step 84, it is again determined whether or not the flag is set. When the flag is not set, the routine proceeds to step 85, where the fuel injection action and the ignition action of the second cylinder 2b are performed. Then, the processing cycle is ended. On the other hand, when the flag is set in step 84, that is, when the reduced cylinder operation is performed, the processing cycle is ended. Therefore, 2 during reduced cylinder operation
The operation of the No. cylinder 2b is stopped.

Next, referring to FIG. 10, the solenoid valves 36, 4
The drive control routine of 0, 41, 42 will be described.
This routine is executed by interruption every fixed crank angle. At step 90, it is judged if the flag is set. When the flag is not set, that is, when all cylinders are in operation, the routine proceeds to step 91. In step 91, the solenoid valve 41 is opened. In this case, the solenoid valve 41 is opened only while the second cam crest 44 of the cam 10b drives the cam side piston 16. Therefore, the valve opening operation of the exhaust valve 7b by the second cam crest 44 is stopped. Next, the routine proceeds to step 92, where the solenoid valve 42 is opened only during the period when the second cam crest 44 of the cam 10c drives the cam side piston 16. Therefore, the valve opening operation of the exhaust valve 7c by the second cam crest 44 is stopped. Then, the processing cycle is ended.

When the flag is set in step 90, that is, when the reduced cylinder operation is performed, then step 9 is executed.
Go to 3. In step 93, the solenoid valve 36 is opened only while the cam crest of the cam 9b drives the cam side piston 16. Therefore, the opening operation of the intake valve 6b is stopped. Next, the routine proceeds to step 94, where the solenoid valve 40 is opened only during the period when the cam crest of the cam 9c drives the cam side piston 16. Therefore, the opening operation of the intake valve 6c is stopped. Then, the processing cycle is ended.

FIG. 11 shows another embodiment of the present invention. Figure 1
Referring to FIG. 1, in this embodiment, the internal combustion engine has a structure similar to that of the embodiment shown in FIG. That is, for example, 2
No. Cylinder 2b intake valve 6b and cam 9 for driving it
A hydraulic device 11 is provided between the intake valve 6c of the third cylinder 2c and a cam 9c for driving the intake valve 6c.
Is provided, the hydraulic device 13 is provided between the exhaust valve 7b of the second cylinder 2b and the cam 10b for driving the same, and the exhaust valve 7c of the third cylinder 2c and the cam 10 for driving it.
A hydraulic device 14 is provided between c. Further, either the all-cylinder operation or the reduced-cylinder operation is performed according to the engine operating state, and during the reduced-cylinder operation, the operation of the second cylinder 2b and the third cylinder 2c is stopped. However, in this embodiment, the second cylinder 2b
The cam 110b for driving the exhaust valve 7b of No. 3 and the cam 110c for driving the exhaust valve 7c of No. 3 cylinder 2c each have only one cam lobe. Moreover, cam 1
The shape of the cam peaks of 10b and 110c is different from the shape of the cam peak of the cam 9a, which has one cam peak, for example.

That is, in the present embodiment, while the corresponding solenoid valves 41, 42 are held closed, the exhaust valves 7b, 7c will pass the exhaust top dead center of the piston of the corresponding cylinder for a while. The cams 110b and 110c are formed so as to be closed after the operation.
Referring to FIG. 12 showing the opening operation of the exhaust valve 7b of the second cylinder 2b, the exhaust valve 7b is opened as indicated by A when the electromagnetic valve 41 is held in the closed state. In FIG. 12, C indicates the opening operation of the intake valve 6b, and the crank angle 0 ° indicates the exhaust top dead center. Further, the opening operation of the exhaust valve 7c of the third cylinder 2c by the cam 110c is the same as the opening operation of the exhaust valve 7b of the second cylinder 2b, and thus the description thereof will be omitted.

By the way, as described above, the exhaust valves 7b, 7
The valve c is opened according to the hydraulic pressures in the three hydraulic chambers 17, 18, 21 of the corresponding hydraulic devices 13, 14, and the hydraulic pressures in these hydraulic chambers 17, 18, 21 are controlled by the solenoid valve 4
1, 42 respectively. In this case, for example, when the solenoid valve 41 is opened when the exhaust valve 7b is opened, the hydraulic oil in the second hydraulic chamber 18 is quickly discharged to the outside of the hydraulic device 13, and as a result, the cam 110b drives the cam side piston 16. However, since the hydraulic pressure in the third hydraulic chamber 21 does not rise, the exhaust valve 7b starts to close. For example, until the crank angle reaches −90 °, the solenoid valve 41
When the solenoid valve 41 is opened when the crank angle reaches −90 ° when B is kept closed, B in FIG.
As shown in FIG. 12, the opening period of the exhaust valve 7b is set to A in FIG.
It can be shortened compared to the case. When the exhaust valve 7b is driven as shown in FIG. 12B, the period during which the exhaust valve 7b is open when the piston descends becomes very short. The opening period of the exhaust valve 7c can be controlled as shown by B in FIG. 12 by opening the electromagnetic valve 42 when the exhaust valve 7c is opened.

Next, referring to FIGS. 13A and 13B, a method of driving the intake valve and the exhaust valve of the second cylinder 2b and the third cylinder 2c which are stopped during the reduced cylinder operation will be described. In FIG. 13, the crank angle of 0 ° indicates the exhaust top dead center of each cylinder. FIG. 13 (A) shows when all cylinders are in operation.
That is, it shows the opening operation of the intake valve and the exhaust valve of the second cylinder 2b and the third cylinder 2c when the second cylinder 2b and the third cylinder 2c are in operation. When the second cylinder 2b and the third cylinder 2c are in operation, the solenoid valve 36 that controls the hydraulic device 11 and the solenoid valve 40 that controls the hydraulic device 12 are always closed, and therefore C1 in FIG.
As shown, the intake valves 6b and 6c are opened by the corresponding cams 9b and 9c, respectively. on the other hand,
Solenoid valve 41 controlling hydraulic device 13 and hydraulic device 14
The solenoid valve 42 for controlling the exhaust valves is closed at the start of the exhaust stroke, and therefore the corresponding cams 110b, 110c start the opening operation of the exhaust valves 7b, 7c. Next, when the crank angle becomes −90 °, the solenoid valves 41, 42 are opened, and as a result, the exhaust valves 7b, 7c are closed as shown by B1 in FIG. 13 (A). In this case, the opening period of the exhaust valves 7b and 7c during the intake stroke is very short.

On the other hand, when the reduced cylinder operation is performed, that is, when the second cylinder 2b and the third cylinder 2c are at rest, the solenoid valves 36,
The valve 40 is opened only during a period in which the cams 9b and 9c that drive the intake valves 6b and 6c drive the corresponding cam-side pistons 16, so that the intake valves 6b and 6c are kept closed. As a result, engine pumping loss can be reduced, and good purification of exhaust gas in the three-way catalyst can be ensured. On the other hand, the solenoid valves 41 and 42 are kept closed during the reduced cylinder operation, and as a result, the exhaust valve 7
b and 7c are opened according to the cam peaks of the cams 110b and 110c, respectively. Therefore, the exhaust valves 7b and 7c are driven as shown by A2 in FIG.
Thus, the opening period of the exhaust valves 7b and 7c during the intake stroke is made longer than when the second cylinder 2b and the third cylinder 2c are in operation. As a result, the second cylinder 2b and the third cylinder 2c
Since the No. 2 cylinder 2b and the No. 3 cylinder 2c can suck the exhaust gas in the exhaust manifold 5 when the piston of No. 2 descends, the cylinder pressures of the No. 2 cylinder 2b and the No. 3 cylinder 2c decrease. Therefore, it is possible to prevent the oil from rising.
In addition, the second cylinder 2b and the third cylinder 2c at rest
No. 2 cylinder 2b by introducing hot exhaust gas into the
And the decrease of the in-cylinder temperature of the No. 3 cylinder 2c can be reduced, and as a result, when the No. 2 cylinder 2b and the No. 3 cylinder 2c should be operated again, the No. 2 cylinder 2b and the No. 3 cylinder 2c can be re-operated well. The start can be secured. The first cylinder 2a
The method of driving the intake valve and the exhaust valve of the fourth cylinder 2d is the same as that of the above-described embodiment described with reference to FIG.

Next, referring to FIG. 14, the solenoid valves 36, 4
The drive control routine of 0, 41, 42 will be described.
This routine is executed by interruption every fixed crank angle. Note that, also in this embodiment, the operating cylinder number control routine shown in FIGS. 8 and 9 is executed. At step 120, it is judged if the flag set in the routine of FIG. 8 is set. When the flag is not set, that is, when all cylinders are in operation, the routine proceeds to step 121. In step 121, the solenoid valve 41 is opened. In this case, the solenoid valve 41 has a crank angle of -9.
The valve is opened when it reaches 0 ° and closed again when the crank angle reaches 90 °. As a result, the opening period of the exhaust valve 7b is shortened. Then, the process proceeds to step 122 and step 1
In 22, the solenoid valve 42 has a crank angle of −90 ° to 90 °.
The valve is opened up to °. Therefore, the opening period of the exhaust valve 7c is shortened. Then, the processing cycle is ended.

When the flag is set in step 120, that is, when the reduced cylinder operation is performed, the routine proceeds to step 123. In step 123, the solenoid valve 36 is opened only while the cam crest of the cam 9b drives the cam side piston 16. Therefore, the opening operation of the intake valve 6b is stopped. Then, the process proceeds to step 124 and step 12
4, the solenoid valve 40 is opened only while the cam crest of the cam 9c drives the cam side piston 16. Therefore, the opening operation of the intake valve 6c is stopped. Then, the processing cycle is ended.

FIG. 15 shows still another embodiment of the present invention. In FIG. 15, the crank angle of 0 ° indicates the exhaust top dead center of each cylinder. No. 2 cylinder 2 in this embodiment
cam for driving the exhaust valve 7b of No. 3b and No. 3 cylinder 2
The exhaust valve 7b, the cam for driving the exhaust valve 7c of c
7c is provided with only one cam crest that opens the valve once during the corresponding exhaust stroke,
Therefore, these cams are formed similarly to the cam 10a for driving the exhaust valve 7a of the first cylinder 2a and the cam 10d for driving the exhaust valve 7d of the fourth cylinder 2d.

When all cylinders are in operation, that is, when the second cylinder 2b and the third cylinder 2c are in operation, the solenoid valves 36 and 40 are kept closed, whereby the intake valves 6b of the second cylinder 2b and the third cylinder 2c, The valve opening operation of 6c is performed according to the respective cam peaks of the corresponding cams 9b and 9c. As a result, the intake valves 6b and 6c are opened as shown by C1 in FIG. 15 (A). Further, the solenoid valves 41, 42 are also kept closed during the all cylinder operation, whereby the exhaust valves 7b, 7c of the second cylinder 2b and the third cylinder 2c are discharged.
The valve opening operation is performed according to the cam peaks of the corresponding cams 10b and 10c. As a result, the valve opening operation of the exhaust valves 7b and 7c is performed as indicated by A1 in FIG.

On the other hand, during the reduced cylinder operation, that is, when the second cylinder 2b and the third cylinder 2c are stopped, the cams 10b, 1
The solenoid valves 41 and 42 are opened only during the period in which 0c drives the corresponding cam side piston 16, whereby the opening operation of the exhaust valves 7b and 7c of the No. 2 cylinder 2b and the No. 3 cylinder 2c is halted. No. 2 cylinder 2b during reduced cylinder operation
Also, the exhaust valves 7b and 7c of the third cylinder 2c are kept closed (see A2 in FIG. 15B). On the other hand, in the reduced cylinder operation, when the cams 9b and 9c start driving the corresponding cam side pistons 16, the solenoid valves 36 and 40 are held in the closed state, and as a result, in FIG. No. 2 cylinder 2b and No. 3 cylinder 2 as shown
the intake valves 6b and 6c of c respectively correspond to the cam 10b,
The valve is opened according to the cam crest of 10c. However, in this embodiment, the crank angle is, for example, 20 during the reduced cylinder operation.
The solenoid valves 36 and 40 are opened when the temperature becomes °, and as a result, as shown in FIG.
5 (B), as indicated by B2, the intake valve 6b,
6c is urged in the valve closing direction. Therefore, during reduced cylinder operation,
The opening period of the intake valves 6b and 6c in each intake stroke of the second cylinder 2b and the third cylinder 2c is longer than that when the second cylinder 2b and the third cylinder 2c are in operation (see C2 in FIG. 15B). Will be shortened. Therefore, during the reduced cylinder operation, it is possible to prevent the oil pumping loss from increasing in the second cylinder 2b and the third cylinder 2c while preventing the engine pumping loss from increasing. At this time, the second cylinders 2b and 3
Since the exhaust valves 7b and 7c of the No. 2 cylinder 2c are kept closed, it is possible to prevent air from being discharged into the exhaust manifold 5 through the No. 2 cylinder 2b and the No. 3 cylinder 2c. It is possible to ensure a good exhaust gas purifying action in the three-way catalyst. The other operation of the internal combustion engine and the method of driving the intake valve and the exhaust valve are the same as those in the embodiment shown in FIG.

FIG. 16 shows still another embodiment of the present invention. In FIG. 16, the crank angle of 0 ° indicates the exhaust top dead center of each cylinder. In this embodiment, the cam 9b for driving the intake valve 6b of the second cylinder 2b has a first cam mountain for opening the intake valve 6b during the intake stroke and a second cam mountain for opening during the explosion stroke. Is provided. Similarly, a cam 9 for driving the intake valve 6c of the third cylinder 2c
The c has a first cam crest that opens the intake valve 6c during the intake stroke and a second cam crest that opens during the explosion stroke. On the other hand, cams 10b and 10c for driving the exhaust valves 7b and 7c of the second cylinder 2b and the third cylinder 2c, respectively.
Is provided with one cam crest that opens the corresponding exhaust valve 7b, 7c once each during the exhaust stroke. Generally, when forming a pair of cam ridges for one cam, it becomes complicated to form these cam ridges.
This is particularly complicated when the angle between the apex of the first cam lobe and the apex of the second cam lobe is small. However, in this embodiment, the apex of the first cam peak that opens the intake valves 6b and 6c formed on the cams 9b and 9c during the intake stroke, and the first cam peak that opens the intake valves 6b and 6c during the explosion stroke. The angle between the vertices of the two cam peaks is about 180 °, so the cams 9b,
A pair of cam ridges can be formed on 9c relatively easily.

When the second cylinder 2b and the third cylinder 2c are in operation (when all cylinders are in operation), the intake valves 6b and 6c of the second cylinder 2b and the third cylinder 2c are the first cam peaks of the corresponding cams 9b and 9c, respectively. The valve is opened during the intake stroke by (Fig. 16 (A)).
C1). However, the solenoid valve 3 is operated only while the second cam crests of the cams 9b and 9c drive the cam side piston 16.
6 and 40 are opened, and as a result, B in FIG.
1, the intake valves 6b and 6c are prevented from opening during the explosion stroke. When the second cylinder 2b and the third cylinder 2c are in operation, the exhaust valves 7b and 7c of the second cylinder 2b and the third cylinder 2c are A1 in FIG. 16 (A).
As shown, the valve is opened during the exhaust stroke.

On the other hand, when the second cylinder 2b and the third cylinder 2c are at rest (during reduced cylinder operation), the cams 9b and 9c are in the first positions.
The solenoid valves 36 and 40 are opened only during the period when the cam peaks drive the corresponding cam-side pistons 16, and as a result, the intake valve 6 as shown by C2 in FIG. 16 (B).
The valves b and 6c are prevented from opening during the intake stroke. As a result, the engine pumping loss can be reduced during the reduced cylinder operation. On the other hand, the electromagnetic valves 36 and 40 are closed during the period in which the second cam peaks of the cams 9b and 9c drive the corresponding cam side pistons 16, respectively, and as a result, FIG.
At B2, the intake valves 6b, 6c are opened during the explosion stroke. As a result, air is sucked into the second cylinder 2b and the third cylinder 2c via the intake valves 6b and 6c, so that it is possible to prevent the oil from rising during the reduced cylinder operation. Further, at this time, since the exhaust valves 7b and 7c are held in the closed state as indicated by A2 in FIG. 16B, the air is not burned through the second cylinder 2b and the third cylinder 2c. Exhaust manifold 5
It can be prevented from being discharged inside.

In the embodiment described above with reference to FIG. 16, the intake valves 6b of the second cylinder 2b and the third cylinder 2c,
A second cam lobe is formed on each of the cams 9b, 9c for driving the 6c, and the intake valves 6b, 6c are opened by the second cam lobe during the cylinder reduction operation during the explosion stroke. However, the second cylinder 2b and the third cylinder 2
a cam 10b for driving each exhaust valve 7b, 7c of c,
Second cam ridges are formed on each of 10c, and the exhaust valves 7b, 7c are opened by the second cam ridges during the explosion stroke during the cut-off cylinder operation, or the opening period of the exhaust valves 7b, 7c during the explosion stroke is activated. You may make it longer than time. In this case, high temperature exhaust gas is introduced into the second cylinder 2b and the third cylinder 2c at the time of rest, and as a result, the in-cylinder temperature of the second cylinder 2b and the third cylinder 2c can be prevented from lowering at the time of rest.

FIG. 17 shows still another embodiment of the present invention. Referring to FIG. 17, similarly to the embodiment shown in FIG. 1, the intake valve 6a of the first cylinder 2a and the intake valve 6d of the fourth cylinder 2d are directly driven by the corresponding cams 9a and 9d, respectively. 2b intake valve 6b and 3rd cylinder 2
The intake valve 6c of c corresponds to the corresponding hydraulic devices 11, 12
It is driven by cams 9b and 9c via. Further, the exhaust valve 7b of the second cylinder 2b and the exhaust valve 7c of the third cylinder 2c
Is connected to the cam 1 via the corresponding hydraulic devices 13 and 14, respectively.
Driven by 0b, 10c, and these cams 10b, 10c
c is the two cam ridges 43, as described with reference to FIG.
44 are provided respectively. Further, in the present embodiment, the exhaust valve 7a of the first cylinder 2a and the exhaust valve 7d of the fourth cylinder 2d.
Is also driven by cams 130a and 130d via corresponding hydraulic devices 131 and 132, respectively. These cams 130a, 130d are cams 10b, 10
Similar to c, it has two cam peaks 43 and 44, respectively, and therefore the exhaust valves 7a and 7d are opened by the first cam peak 43 in the exhaust stroke and by the second cam peak 44 in the intake stroke. It is like this. The hydraulic devices 131 and 132 are configured similarly to the hydraulic device 11, for example, and the hydraulic device 131 is controlled by the solenoid valve 133, and the hydraulic device 132 is controlled by the solenoid valve 134.
These solenoid valves 133 and 134 are configured similarly to the solenoid valve 36, for example. In this embodiment as well, similar to the embodiment shown in FIG. 1, either the all-cylinder operation or the reduced-cylinder operation is performed according to the engine operating state, and during the reduced-cylinder operation, the second cylinder 2b and the third cylinder 2c are operated. The operation is suspended.

Next, a method of driving the intake valve and the exhaust valve of each cylinder will be described with reference to FIG. In FIG. 18, the crank angle of 0 ° indicates the exhaust top dead center of each cylinder. First, during the reduced cylinder operation, that is, when the No. 2 cylinder 2b and the No. 3 cylinder 2c are at rest, these No. 2 cylinders 2b and 3 are
A method of driving each intake valve and each exhaust valve of the second cylinder 2c will be described. During the reduced-cylinder operation, the solenoid valve 3 is operated only while the cams 9b and 9c drive the corresponding cam-side pistons 16.
6 and 40 are opened, whereby the intake valve 6b of the second cylinder 2b and the intake valve 6c of the third cylinder 2c whose operation is stopped as indicated by C2 in FIG. Each is paused. As a result, the intake valves 6b and 6c are kept closed during the reduced cylinder operation, which prevents an increase in engine pumping loss and at the same time prevents air from being discharged into the exhaust manifold 5 without being burnt. Thus, good purification of exhaust gas in the three-way catalyst can be ensured.

Further, during the reduced cylinder operation, the solenoid valves 41 and 42 are opened only during the period in which the first cam crests 43 of the cams 10b and 10c drive the corresponding cam-side pistons 16, and as a result, in FIG. 18B. As indicated by A2, the exhaust valves 7b, 7 by the first cam crests 43 of the cams 10b, 10c.
The valve opening operation of c is stopped. When the driving of the cam side piston 16 by the first cam crest 43 is completed, the solenoid valves 41 and 42 are closed again, and as a result, the cam side piston 16 is moved to the cam 10
It is driven by the second cam crest 44 of b and 10c, and thus the exhaust valves 7b and 7c are opened as shown by B2 in FIG. 18 (B). Thus, the exhaust valve 7b of the second cylinder 2b and the exhaust valve 7c of the third cylinder 2c, which are not in operation, are opened during the intake stroke, so that oil rises in the second cylinder 2b and the third cylinder 2c. Can be prevented. Further, in the present embodiment, the exhaust valve 7 by the first cam crests 43 of the cams 10b and 10c during the reduced cylinder operation.
By stopping the valve opening operation of b, 7c, the exhaust valve 7b,
Vibration and noise when 7c is seated on the valve seat can be reduced as compared with the embodiment shown in FIG. In this embodiment, the exhaust valve 7b of the second cylinder 2b and the exhaust valve 7c of the third cylinder 2c are set to the maximum open period during the reduced cylinder operation, that is, the second cam crests 44 correspond to each other. As the cam side piston 16 is driven, the exhaust valves 7a, 7b, 7c and 7d are driven.

On the other hand, when all cylinders are in operation, that is, when the second cylinder 2b and the third cylinder 2c are driven, 2
The intake valves and exhaust valves of the No. cylinder 2b and No. 3 cylinder 2c are driven as shown in FIG. 18 (A). That is, the solenoid valves 36 and 40 are kept closed during all cylinder operation,
As a result, the intake ports 6b and 6c are opened by the corresponding cam peaks of the cams 9b and 9c as shown by C1 in FIG. 18 (A). On the other hand, the solenoid valves 41 and 42 are basically kept closed during the all-cylinder operation. As a result, the exhaust valves 7b and 7c first correspond to the corresponding cams 10.
18b by the first cam crests 43 of the cams 10b and 10c, the valve is opened during the exhaust stroke as indicated by A1 in FIG. 18A.
As indicated by B1 in (A), the valve is opened during the intake stroke. Therefore, the second cylinder 2b and the third cylinder 2
When c is in operation, the exhaust gas in the exhaust manifold 5 is sucked into each combustion chamber of the second cylinder 2b and the third cylinder 2c as so-called EGR gas, and as a result, the temperature rise in the combustion chamber can be reduced. As a result, the amount of NO _x discharged into the exhaust manifold can be reduced.

On the other hand, the intake valves 6a and 6d and the exhaust valves 7a and 7d of the first cylinder 2a and the fourth cylinder 2d are the intake valves 6b of the second cylinder 2b and the third cylinder 2c, respectively, during all cylinder operation. 6c and the exhaust valves 7b, 7c are driven by the same driving method. As shown in FIG. 17, a hydraulic device is not provided for the intake valves 6a and 6d, so that the intake valves 6a and 6d can be operated as shown in FIG.
At C1, each valve is opened during the intake stroke. On the other hand, the solenoid valves 133 and 134 for controlling the opening operation of the exhaust valves 7a and 7d are basically kept in the closed state, so that the exhaust valves 7a and 7d are first of all placed in the corresponding cams 130a and 130d. The first cam crest 43 opens the valve during the exhaust stroke as indicated by A1 in FIG. 18A, and then the second cam crest 44 of the cams 130a and 130d causes the intake stroke as indicated by B1 in FIG. 18A. It is sometimes opened. Therefore, the exhaust gas in the exhaust manifold 5 is sucked into the combustion chambers of the first cylinder 2a and the fourth cylinder 2d as so-called EGR gas, and as a result, the NO _x amount can be reduced.

By the way, since the engine output must be increased when the engine load is high, it is necessary to increase the intake air amount of each cylinder. However, the exhaust valves of the operating cylinders, that is, the exhaust valves 7a, 7a of the first cylinder 2a and the fourth cylinder 2d, respectively.
d and the exhaust valves 7b, 7c of the second cylinder 2b and the third cylinder 2c during the all-cylinder operation are opened by the corresponding second cam ridges 44 during the intake stroke, the second cam ridges 44 The exhaust valve 7a, 7b, 7c, 7d is opened by the maximum opening period, and the exhaust valve 7a, 7b, 7c, 7d is opened by the second cam crest 44.
/ N, the intake air amount Q of each cylinder increases as the engine load Q / N increases, and the EGR gas amount also increases. As a result, the intake air amount Q increases as the engine load Q / N increases. Cannot be increased sufficiently. Therefore, in the present embodiment, the exhaust valves 7a, 7b, 7c, and
The corresponding solenoid valves 133, 4 during the valve opening operation of 7d
1, 42, 134 are opened, and the solenoid valve 133, 41, 42, 134 is opened earlier as the engine load Q / N becomes higher, that is, the exhaust valves 7a, 7b, 7c, 7d are closed. As the engine load Q / N is increased by advancing the timing, the exhaust valves 7a, 7b, 7c,
The valve opening period of 7d is shortened. The valve opening operation of each exhaust valve 7a, 7b, 7c, 7d at this time is shown by D1 in FIG. 18A, for example. As a result, as the engine load Q / N becomes higher, the EGR gas sucked into the combustion chamber of each cylinder is decreased, so that a large intake air amount can be secured at the time of high engine load, and therefore at the time of high engine load. The engine output can be secured. The solenoid valves 133, 41, 42, and 134 are connected to the exhaust valves 7 respectively.
When the a, 7b, 7c and 7d are opened to shorten the valve opening period, when the second cam crest 44 of each cam stops driving the corresponding cam side piston 16, each solenoid valve 133, 41 , 42, and 134 are closed.

Each exhaust valve 7a, 7 by the second cam crest 44
The valve opening periods of b, 7c and 7d are stored in advance in the ROM 53 in the form of the map shown in FIG. Referring to FIG. 19, when the engine load Q / N is extremely low, the valve opening period is maintained at the maximum opening period, and when the engine load Q / N is full load, the exhaust valves 7a, 7b, 7c, 7d are closed. The valve state is maintained, so that at this time, no EGR gas is supplied to each combustion chamber.

Next, referring to FIG. 20, the solenoid valves 36, 4
The drive control routine of 0, 41, 42 will be described.
This routine is executed by interruption every fixed crank angle. Note that, also in this embodiment, the operating cylinder number control routine shown in FIGS. 8 and 9 is executed. First, at step 140, the second cam mountain 4 from the map shown in FIG.
The open period of the exhaust valves 7a, 7b, 7c, 7d by 4 is calculated. Then, the procedure proceeds to step 141 and step 14
At 1, it is determined whether or not the flag set in the routine of FIG. 8 is set. When the flag is not set, that is, when all cylinders are in operation, the routine proceeds to step 142. At step 142, the opening period of the exhaust valve 7a by the second cam crest 44 of the cam 130a is calculated while the exhaust valve 7a is being opened by the first cam crest 43 of the cam 130a. The solenoid valve 133 is driven so that the valve period is reached. Next, in step 143, the cam 10 is operated.
The opening period of the exhaust valve 7b by the second cam crest 44 of the cam 10b is set to the valve opening period calculated in step 140 while the opening operation of the exhaust valve 7b by the first cam crest 43 of b is performed. Then, the solenoid valve 41 is driven. Next, the routine proceeds to step 144, and at step 144, the cam 10
The opening period of the exhaust valve 7c by the second cam crest 44 of the cam 10c is set to the valve opening period calculated in step 140 while the opening operation of the exhaust valve 7c by the first cam crest 43 of c is performed. The solenoid valve 42 is driven. Next, the routine proceeds to step 145, and at step 145, the cam 13
The opening period of the exhaust valve 7d by the second cam crest 44 of the cam 130d is set to the valve opening period calculated in step 140 while the opening operation of the exhaust valve 7d by the 0d first cam crest 43 is performed. Then, the solenoid valve 134 is driven. Then, the processing cycle is ended.

When the flag is set in step 141, that is, when the reduced cylinder operation is performed, the routine proceeds to step 146. In step 146, the solenoid valve 36 is driven so that the opening operation of the intake valve 6b is stopped. Next, in step 147, the intake valve 6c
The solenoid valve 40 is driven so that the valve opening operation of 1 is stopped. Next, the routine proceeds to step 148, where at step 148, the opening period of the exhaust valve 7a by the second cam crest 44 of the cam 130a is set while the opening operation of the exhaust valve 7a by the first cam crest 43 of the cam 130a is performed. 140
Solenoid valve 133 so that the valve opening period calculated in
Is driven. Next, in step 149, the opening period of the exhaust valve 7b by the second cam crest 44 of the cam 10b is stopped while the opening operation of the exhaust valve 7b by the first cam crest 43 of the cam 10b is stopped. The solenoid valve 41 is driven so that the maximum valve opening period is reached. Next, at step 150, at step 150, the opening period of the exhaust valve 7c by the second cam crest 44 of the cam 10c is stopped while the opening operation of the exhaust valve 7c by the first cam crest 43 of the cam 10c is stopped. Solenoid valve 4 for the maximum valve opening period
2 is driven. Next, the routine proceeds to step 151. At step 151, the cam 130 is opened while the exhaust valve 7d is opened by the first cam crest 43 of the cam 130d.
The electromagnetic valve 134 is driven so that the opening period of the exhaust valve 7d by the second cam crest 44 of d becomes the opening period calculated in step 140. Then, the processing cycle is ended.

By the way, in a normal internal combustion engine in which the number of operating cylinders is changed according to the engine operating state, at the time of engine starting, that is, for example, the starter motor switch is ON or the starter motor switch is OFF. When the engine is idling and the engine cooling water temperature is lower than the set temperature, the reduced-cylinder operation is prohibited, that is, the all-cylinder operation is performed to start the engine as quickly as possible. However, as in the embodiment described above with reference to FIG. 17, the exhaust valves 7a, 7b, 7c, 7d are opened by the corresponding second cam crests 44 during the intake stroke of each cylinder during all-cylinder operation. E to each cylinder by
If the GR gas is supplied, a part of the relatively high temperature exhaust gas discharged from each combustion chamber into the exhaust manifold 5 will flow back into each combustion chamber without reaching the three-way catalyst. The amount of exhaust gas reaching the original catalyst is reduced, and as a result, the three-way catalyst cannot be quickly heated to the catalyst activation temperature by the heat of the exhaust gas at the time of starting the engine. May not be properly purified. Moreover, in the embodiment shown in FIG. 17, each exhaust valve 7 by the second cam crest 44 is operated during idling operation.
The valve opening periods of a, 7b, 7c, and 7d are set to the maximum valve opening period, and in this case, quick heating of the three-way catalyst at the time of engine start is further hindered.

Therefore, when the engine is started, that is, when the starter motor switch is ON, or when the starter motor switch is OFF and the idling operation is in progress and the engine cooling water temperature is lower than the set temperature,
The all-cylinder operation may be performed, and the opening period of each exhaust valve 7a, 7b, 7c, 7d by the second cam crest 44 of the corresponding cam may be shortened as compared with the idling operation after completion of warm-up. . As a result, when starting the engine, EG
Since the amount of exhaust gas supplied to each combustion chamber as R gas decreases, the amount of exhaust gas reaching the three-way catalyst increases, and therefore the heat of the exhaust gas rapidly heats the three-way catalyst to the catalyst activation temperature. Therefore, it is possible to ensure good purification of the exhaust gas at the time of starting the engine. FIG. 17
In the embodiment shown in FIG.
a, 7b, 7c and 7d are opened by the second cam crest 44 of the corresponding cam for the maximum valve opening period. In this case, when the engine is started, the exhaust valves 7a, 7b, 7c, 7d
The corresponding solenoid valves 133, 41, 42, and 134 when the corresponding cams are opened by the second cam crests 44, respectively.
To open each exhaust valve 7a, 7b by the second cam crest 44,
The valve opening period of 7c and 7d may be set to, for example, half of the maximum valve opening period.

FIG. 21 shows a drive control routine for the solenoid valves 36, 40, 41, 42 when the engine is started in the embodiment shown in FIG. This routine is started when the starter motor switch is turned on, and is executed by interruption at every constant crank angle. Referring to FIG. 21, first, at step 160, it is judged if the starter motor switch is ON. The routine shown in FIG. 21 starts to be executed when the starter motor switch is turned on. Therefore, when the process proceeds to step 160 for the first time after the starter motor switch is turned on, the process proceeds to step 161. In step 161, the warm-up completion flag that is set when the warm-up operation is completed is reset. Next, in step 162, the cam 130a is opened while the exhaust valve 7a is being opened by the first cam crest 43 of the cam 130a.
The solenoid valve 133 is driven so that the opening period of the exhaust valve 7a by the second cam lobe 44 is half the maximum opening period.
Next, at step 163, at step 163, the exhaust valve 7b is opened by the first cam crest 43 of the cam 10b while the exhaust valve 7b is opened by the second cam crest 44 of the cam 10b. The solenoid valve 41 is driven so as to be half the valve period. Next, at step 164, at step 164, the first cam crest 43 of the cam 10c is formed.
The solenoid valve 42 is driven so that the valve opening operation of the exhaust valve 7c is performed and the valve opening period of the exhaust valve 7c by the second cam crest 44 of the cam 10c is half the maximum valve opening period. Next, at step 165, at step 165, the opening period of the exhaust valve 7d by the second cam crest 44 of the cam 130d is maximized while the opening operation of the exhaust valve 7d by the first cam crest 43 of the cam 130d is performed. The solenoid valve 134 is driven so as to be half the valve period. Then, the processing cycle is ended.

Next, when the starter motor switch is turned off, the routine proceeds from step 160 to step 166. At step 166, it is judged if the idling operation is currently performed. When the engine is idling, the routine proceeds to step 167, where it is judged if the engine cooling water temperature T is lower than a preset temperature TW. When T <TW, the process proceeds to step 161. In this case, since the warm-up completion flag has already been reset, the above-described steps 161 to 1
Proceed to 65 and then end the processing cycle.

When the idling operation is not being performed at step 166, or when T ≧ TW at step 167.
If, then the process proceeds to step 168. In step 168, it is determined that the warm-up operation is completed, and the warm-up completion flag is set. Then, the processing cycle is ended. Note that once the warm-up completion flag is set, execution of the operating cylinder number control routine shown in FIGS. 8 and 9 is started, and FIG.
The execution of the solenoid valve drive control routine shown in is started.

In the above-described embodiment, the exhaust valve 7a, when the starter motor switch is ON, or even when the starter motor switch is OFF during idling operation and the engine cooling water temperature is lower than the set temperature. 7
The valve opening period by the second cam crests 44 of b, 7c, 7d is shortened to reduce the EGR gas amount. However, a sensor for detecting the temperature of the three-way catalyst is provided in the three-way catalyst, and when the temperature of the three-way catalyst is lower than the activation temperature, the valve opening period by the second cam crest 44 of the exhaust valves 7a, 7b, 7c, 7d. May be shortened.

As described above, the normal internal combustion engine does not perform the reduced cylinder operation when the engine is started. However, in the case where the hydraulic device is used to control the opening operation of the intake valve and the exhaust valve as in the present embodiment and the engine-driven pump 33 is used to supply the hydraulic oil to the hydraulic device. May perform the reduced-cylinder operation for a very short time after the starter motor switch is turned on.
When the reduced-cylinder operation is performed, for example, in the embodiment shown in FIG. 17, the exhaust valve 7 is provided to at least the hydraulic devices 131 and 132.
If a sufficient hydraulic pressure to drive the a and 7d can be supplied, the engine can be started, so that the engine can be started quickly. In this case, the second cylinder 2 which is inactive
The valve opening period by the second cam crest 44 corresponding to the exhaust valve 7b of b and the third cylinder 2c may be shorter than the maximum valve opening period. As a result, the three-way catalyst can be heated more quickly when the engine is started.

FIG. 22 shows another embodiment of a cam having two cam ridges, for example, the cam 10b. FIG. 22 (A)
Referring to, the top of the first cam mountain 43 and the second cam mountain 44
The angle between the vertices is 146 °, for example, and as a result, as shown by B in FIG.
The valve opening operation of the exhaust valve 7b is performed later than in the embodiment shown in FIG. That is, the lift amount of the intake valve 6b (see FIG.
The exhaust valve 7b is started to open by the second cam crest 44 at or near the crank angle at which (C) in (B) is substantially maximum, and the exhaust valve 7b is closed at about the same time as the intake valve 6b is closed. 7b is closed. In this case, the exhaust valve 7
The valve b is open even after the piston starts to rise above the intake bottom dead center (180 °). As a result, when the valve opening operation of the intake valve 6b is stopped during the reduced cylinder operation, the exhaust valve 7b is secondly opened by the cam crest 44 to suck the exhaust gas into the combustion chamber during the intake stroke, so that the piston moves. By preventing the pressure in the combustion chamber from decreasing when descending, and then discharging part of the exhaust gas in the combustion chamber into the exhaust manifold 5 when the piston rises, the exhaust valve 7b and the intake valve 6b are It is possible to reduce the compression work of the engine when the valve is closed. Thus, the engine efficiency can be further improved.

In the embodiments described so far, each exhaust valve 7 when the second cylinder 2b and the third cylinder 2c are at rest.
b, 7c valve opening period extension action, that is, the opening operation of each exhaust valve 7b, 7c that makes the valve opening period of each exhaust valve 7b, 7c during the intake stroke during the reduced cylinder operation longer than that during operation The control is performed once for each intake stroke of the corresponding cylinder. However, the operation of extending the opening period of each of the exhaust valves 7b and 7c may be performed once every time the intake stroke of the corresponding cylinder is performed a plurality of times. In this case, the second cylinder 2b and the third cylinder 2
Since the number of times each exhaust valve 7b, 7c is opened during the intake stroke is reduced when c is stopped, the number of times each exhaust valve 7b, 7c is seated on its respective valve seat is reduced, resulting in engine noise and vibration. Can be reduced compared to the embodiment shown in FIG. 1, for example.

[0066]

[0067]

According to the first aspect of the present invention, since each exhaust valve is opened by the second cam lobe during the intake stroke, the exhaust gas in the engine exhaust passage is sucked into each cylinder, resulting in EGR in the operating cylinder. Since the gas is supplied, the amount of NO _x discharged into the engine exhaust passage can be reduced. In the deactivated cylinder, the cylinder pressure is prevented from lowering when the piston descends, so oil rise can be prevented, and at this time the intake valve is held closed, reducing engine pumping loss. Exhaust gas can be satisfactorily purified by the catalyst. Further, it is possible to reduce the decrease in the in-cylinder temperature of the deactivated cylinders, so that when the deactivated cylinders are operated again, these cylinders can be favorably restarted. Further , the EGR gas amount is reduced as the engine load is higher, so that the intake air amount of each cylinder can be secured,
Therefore, the engine output can be secured at the time of high engine load. Et al is, since the EGR gas amount at the time of engine starting operation is decreased from the time of idling after completion of warming-up can be heated catalyst promptly.

In the second aspect , since the intake valve of the idle cylinder is opened in the explosion stroke, air is sucked into the idle cylinder,
As a result, it is possible to prevent the oil from rising in the idle cylinder. Further, at this time, since the exhaust valve of the inactive cylinder is held in the closed state, the air is prevented from being discharged into the engine exhaust passage without being burned, and therefore, the exhaust gas is properly purified by the catalyst. You can In the third aspect of the invention, the exhaust valve of the idle cylinder is opened during the explosion stroke, so that exhaust gas is sucked into the idle cylinder, and as a result, oil rise in the idle cylinder can be prevented. Further, at this time, since the intake valve of the deactivated cylinder is held in the closed state, the air is prevented from being discharged into the engine exhaust passage without being burned, so that the exhaust gas can be properly purified by the catalyst. You can

[Brief description of drawings]

FIG. 1 is an overall view of an internal combustion engine showing an embodiment of the present invention.

FIG. 2 is a sectional view of a hydraulic device.

3 is a cross-sectional view of the hydraulic device taken along line III-III in FIG.

FIG. 4 is a diagram showing a part of a hydraulic circuit.

5A and 5B are views for explaining the structure and action of the exhaust valve driving cams of the second cylinder and the third cylinder in the embodiment shown in FIG.

FIG. 6 is a diagram for controlling the number of operating cylinders.

FIG. 7 is a diagram illustrating an opening operation of an intake valve and an exhaust valve in the embodiment shown in FIG.

FIG. 8 is a flowchart for controlling the number of operating cylinders.

FIG. 9 is a flowchart for controlling the operation of cylinders.

10 is a flow chart for controlling drive of a solenoid valve in the embodiment shown in FIG.

FIG. 11 is an overall view of an internal combustion engine showing another embodiment of the present invention.

12 is a diagram for explaining the valve opening action of the exhaust valves by the exhaust valve driving cams of the second cylinder and the third cylinder in the embodiment shown in FIG.

13 is a diagram for explaining the opening operation of the intake valve and the exhaust valve of the second cylinder and the third cylinder in the embodiment shown in FIG.

FIG. 14 is a flow chart for controlling drive of a solenoid valve in the embodiment shown in FIG.

FIG. 15 is a diagram for explaining an opening operation of an intake valve and an exhaust valve in yet another embodiment of the present invention.

FIG. 16 is a diagram for explaining an opening operation of an intake valve and an exhaust valve in yet another embodiment of the present invention.

FIG. 17 is an overall view of an internal combustion engine showing still another embodiment of the present invention.

FIG. 18 is a diagram for explaining the opening operation of the intake valve and the exhaust valve in the embodiment shown in FIG.

FIG. 19 is a diagram showing a valve opening period of an exhaust valve by a second cam lobe.

20 is a flow chart for controlling the drive of the solenoid valve in the embodiment shown in FIG.

FIG. 21 is a flowchart for controlling driving of a solenoid valve at the time of starting the engine.

FIG. 22 is a diagram showing another embodiment of the exhaust valve driving cams of the second cylinder and the third cylinder.

[Explanation of symbols]

2a, 2d ... Cylinder (also operated during reduced cylinder operation) 2b, 2c ... Cylinder (paused during reduced cylinder operation) 6a, 6b, 6c, 6d ... Intake valve 7a, 7b, 7c, 7d ... Exhaust valve 9a, 9b, 9c, 9d ... Intake valve driving cam 10a, 10b, 10c, 10d ... Exhaust valve driving cam 11, 12, 13, 14 ... Hydraulic system 36, 40, 41, 42 ... Solenoid valve 16 ... Cam side piston 17, 18, 21 ... Hydraulic chamber 23 ... Valve side piston 43 ... 1st cam mountain 44 ... second cam mountain

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI F02M 25/07 550 F02M 25/07 550H 580 580C (72) Inventor Shinji Kato 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd. (72) Inventor Hideo Saruhashi 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (72) Inventor Yoshihiro Iwashita 1 Toyota Town, Toyota City, Aichi Toyota Motor Co., Ltd. (56) References JP-A-57-38639 (JP, A) JP-A-58-195006 (JP, A) JP-A-58-176428 (JP, A) Actual opening Sho-59-19906 (JP, U) Actual opening Sho-53-92510 (JP , U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F02D 17/02 F02D 13/02 F02D 13/06 F01L 13/00 303 F02M 25/07

Claims (3)

(57) [Claims] 1. The number of operating cylinders is changed according to the operating condition of the engine.
In an internal combustion engine designed to
Each exhaust valve has a first cam peak and a second cam peak.
Form and open the exhaust valve during the exhaust stroke by the first cam peak
And the second cam mountain causes the exhaust valve to move during the intake stroke.
Open the valve, and stop when cylinders should stop operating
Keep the intake valve of the cylinder closed and
Of the piston and exhaust valve driven by the cam lobe
A hydraulic chamber is formed between the system tops and the hydraulic pressure in the hydraulic chamber is controlled.
As the engine load increases due to
To shorten the opening period of the exhaust valve of the operating cylinder due to
However, at the start of the engine, at least due to the second cam mountain
Idling after warming up the exhaust valve opening period of the operating cylinder
A valve operating system for an internal combustion engine that is shorter than during normal operation . 2. The number of operating cylinders is changed according to the operating condition of the engine.
In the internal combustion engine,
The intake valve drive cam of the cylinder that is deactivated accordingly
The first cam crest that opens the air valve during the intake stroke and the intake
With a second cam lobe for opening the valve during the explosion stroke
However, when the cylinder is operating, the intake valve is opened by the first cam peak.
The valve operation is performed and the intake valve is opened by the second cam peak.
The work is stopped, and when the cylinder is stopped
The opening operation of the intake valve is stopped and the second cam crest is used.
And a valve opening control means for opening the intake valve.
To keep the exhaust valve of the cylinder closed when the cylinder is at rest
Valve operating system for an internal combustion engine that was. 3. The number of operating cylinders is changed according to the operating condition of the engine.
In the internal combustion engine,
The exhaust valve drive cam of the cylinder
The first cam crest that opens the air valve during the exhaust stroke and the exhaust
With a second cam lobe for opening the valve during the explosion stroke
However, when the cylinder is in operation, the exhaust valve is opened by the first cam lobe.
The valve operation is performed and the exhaust valve is opened by the second cam crest.
The work is stopped, and when the cylinder is stopped
The opening operation of the exhaust valve is stopped and the second cam mountain
A valve opening control means for opening the exhaust valve.
To keep the intake valve of the cylinder closed when the cylinder is at rest
Valve operating system for an internal combustion engine that was.