JPH059610B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an improvement in a cylinder number control engine that suspends the operation of some cylinders and performs reduced-cylinder operation during specific operations such as when the engine is under light load.

(Prior art) Conventionally, fuel efficiency tends to be better during high-load operation, so in multi-cylinder engines, fuel supply to some cylinders is cut off when the engine load is light, and the fuel supply is cut off to reduce fuel consumption. There is a known cylinder number control engine that performs cylinder reduction operation so as to relatively increase the load on the remaining operating cylinders and improve overall fuel efficiency in the light load range (for example,
(See No. 338).

However, in such engines, the same valve timing is used both during cylinder reduction and full cylinder operation, so the crankshaft
The cycle time is long for just one explosion per rotation, and since the charging efficiency is high and the combustion pressure is large, torque fluctuations are large, which is disadvantageous in terms of vibration compared to when all cylinders are operated. The present invention attempts to reduce vibration by changing valve timing.

Incidentally, as a device for changing valve timing, a tappet device for driving a valve of an internal combustion engine, for example, disclosed in Japanese Publication No. 34-10554, has been known.

(Object of the Invention) An object of the present invention is to reduce vibration during cylinder reduction operation in an engine with controlled number of cylinders.

(Structure of the Invention) In order to achieve the above-mentioned object, the structure of the present invention includes a first cylinder group whose operation is suspended during a specific operation;
In a cylinder number controlled engine having a second cylinder group that is constantly activated, a control means is provided for controlling the valve timing of the second cylinder group in a direction in which the maximum combustion pressure is lower during reduced-cylinder operation than during full-cylinder operation. It is characterized by:

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

The engine 1 shown in FIG. 1 and FIG. , 1D).

In FIG. 1, 2 is an intake passage, and from the upstream side, an air cleaner (not shown), an air flow sensor 3,
A main intake passage 6 in which a fuel injection valve 4 and a throttle valve 5 are disposed in order, and four branch intake passages 7 that branch from the main intake passage 6 and communicate with the combustion chambers of each cylinder 1A, 1B, 1C, and 1D. It consists of 8, 9, and 10.

Shutter valves 1 are installed in branch intake passages 8 and 9 for the second and third cylinders 1B and 1C, respectively.
1 and 12 are interposed, and the negative pressure signal S ₁ corresponding to the intake negative pressure from the negative pressure sensor 13 and the rotation speed signal S ₂ corresponding to the engine rotation speed from the rotation speed sensor 14 are used. As shown in FIG. 3, when the cylinder number control circuit 15 determines that the intake negative pressure is below the set intake negative pressure Pm and below the set engine rotation speed Nm,
Activate the actuator 16 (for example, an electromagnetic solenoid), close the shutter valves 11 and 12,
It is now possible to operate with fewer cylinders.

17 is an exhaust passage for each cylinder 1A, 1B, 1C,
It is branched into four branch exhaust passages leading to the 1D combustion chamber.

18 is a water temperature sensor which outputs a temperature signal _S3 corresponding to the engine cooling water temperature to the cylinder number control circuit 15, and when it is determined that the engine is in a cold state based on the temperature signal _S3 , other signals are output. Regardless of S ₁ and S ₂ ,
The engine is now running on all cylinders. 19 is a throttle opening sensor, which is linked to the throttle valve 5;
The slot opening signal _S4 is input to the cylinder number control circuit 15, and all cylinders are operated during acceleration.

20 is a fuel injection control circuit which receives an intake air amount signal _S5 from a potentiometer 45 linked to the air flow sensor 3, determines the fuel injection amount according to the intake air amount, and outputs a pulse signal corresponding to the intake air amount signal S5. _S6 is sent to the fuel injection valve 4.

In FIG. 2 showing the first cylinder 1A of the engine shown in FIG.
3 is provided. 24 is a combustion chamber.

Reference numerals 25 and 26 denote an intake port and an exhaust port, respectively, and an intake valve 27 and an exhaust valve 28, which open and close at predetermined timing, are disposed at the openings to the combustion chamber 24, respectively.

The intake valve 27 and the exhaust valve 28 are connected to the cylinder head 2 via valve guides 29, 29, respectively.
3, and is constantly biased upward, that is, in the valve closing direction, by valve springs 30, 30.

At the upper part of the cylinder head 23, intake side and exhaust side valve operating mechanisms 31A and 31B for controlling the opening and closing of the intake and exhaust valves 27 and 28 are provided. The intake side and exhaust side valve mechanisms 31A and 31B have intake side and exhaust side camshafts 32A and 32B that are rotationally driven by an engine crankshaft (not shown), and the camshafts 32A,
32B has a cam 3 corresponding to the intake and exhaust valves 27 and 28.
3A, 33B are formed, and the rotation of the camshafts 32A, 32B opens the intake and exhaust valves 27, 28.
are now controlled to open and close.

Further, the intake side valve operating mechanism 31A is provided with a variable timing mechanism 34 that variably controls the valve timing of the intake valve 27. The variable timing mechanism 34 is configured by a tappet 35 interposed between the cam 33A and the valve stem 27a of the intake valve 27.
and a fitting hole 36a into which the tappet 35 is slidably fitted and held, and a lower surface 36b formed in an arc shape corresponding to the arc-shaped inner surface of the cylinder head 23.
and a rotating member 36 rotatably supported with respect to the intake camshaft 32A, and the rotating member 36 is rotated about the rotation center of the intake camshaft 32A depending on the operating state of the engine. The operating means 37 is also provided.

The rotating member 36 is connected to the intake side camshaft 32
In the portion supported by A, the upper and lower members 36c,
It is divided into 36d parts, which are connected together with bolts 38, 38.

Further, the operating means 37 includes the timing variable mechanism 3
A rotation shaft 39 connected to the upper member 33c of the rotation member 36 of No. 4, and a rotation shaft 39 disposed perpendicularly to the rotation shaft 39 and engaged with the rotation shaft 39, as well as in the left-right direction in FIG. A reciprocating shaft 40 that is capable of reciprocating
and a drive means 41 that converts the rotational motion of a motor into reciprocating motion, causes the reciprocating shaft 40 to reciprocate in the above direction, and rotates the rotary member 36 as described above via the rotary shaft 39. Be prepared.

Then, when the intake side camshaft 32A rotates and the cam 33 presses the pressure receiving part 35a of the tappet 35, and the tappet 35 is pushed up inside the insertion hole 36a, the intake valve 27 is moved against the valve spring 30.
The tappet 35 is pushed down by the pressing portion 35b against the urging force of the tappet 35, and the intake port 25 is opened.

Further, a tappet 42 is also interposed between the valve stem 28a of the exhaust valve 28 and the cam 33B, and the tappet 42 is slidably inserted and held in the insertion hole 3a of the cylinder head 3.

43 is a valve timing control circuit, which outputs a negative pressure signal.
Intake valve 2 according to S ₁ and engine speed signal S ₂
7 is determined, and the drive means 41 is driven with a drive signal _S7 corresponding to the valve timing. 44 is a spark plug.

The variable timing mechanism is provided for the intake valve of each cylinder, so that the drive means 41 can control all the cylinders simultaneously.

With the above configuration, the intake valve 27 is
and the exhaust valve 28 are each provided with an intake side valve mechanism 31.
A and the exhaust side valve operating mechanism 31B control opening and closing at predetermined valve timing. That is, as shown by the solid line in FIG. 4, the exhaust valve 28 opens slightly before the piston's bottom dead center (BDC) and then closes near the top dead center (TDC), while the intake valve 27 opens just before the piston's bottom dead center (BDC). It is also controlled by the base timing, which opens near the point and then closes a little later than the bottom dead center.

Further, when the engine is under high load and at low rotation speed, the variable timing mechanism 34 operates to advance the closing timing of the intake valve 27 compared to the base timing, thereby preventing blowback of intake air and increasing charging efficiency.

On the other hand, when the engine is under high load and at high speed, the variable timing mechanism 34 operates and rotates the rotating member 36 counterclockwise to change the closing timing of the intake valve 27 to a later side than the base timing. The flow of air into the exhaust passage 17 is promoted, and the introduction of fresh air in the next stroke is promoted by utilizing the intake inertia caused by the increased amount of intake air, thereby increasing the filling efficiency.

During idling operation in the reduced cylinder operation range,
In the operating first and fourth cylinders 1A and 1D, the closing timing of the intake valves 27 is delayed from the base timing, so some blowback of intake air occurs, reducing charging efficiency and reducing the effective compression ratio. Become. Therefore, since the maximum combustion pressure is not increased and the torque fluctuation is not increased, vibrations can be reduced and a good operating condition similar to that in all cylinder operation can be achieved. As the engine speed and engine load increase, the closing timing of the intake valves 27 is gradually advanced so as to approach the base timing, and in the switching region to all-cylinder operation, the closing timing is almost the base timing.

In the above embodiment, the closing timing of the intake valve 27 is delayed from the base timing only during idle operation with particularly severe vibration during cylinder reduction operation. The closing time may be delayed.

In addition to the above-mentioned embodiment, as shown by the solid line in FIG.
It is also possible to increase the overlap period of 28, thereby slowing combustion and lowering the maximum combustion pressure, thereby reducing vibration. In addition, a well-known valve lift amount variable means can also be used. That is, as shown in FIG. 7, in the all cylinder operating region,
During high load, the lift amount is increased compared to normal operation, that is, the base timing, and the closing timing of the intake valve 27 is delayed, while in the cylinder reduction operation region, as shown in FIG. 8, the lift amount is higher than the base timing during idle operation. This reduces pumping loss by advancing the closing timing of the intake valve 27, reduces vibration by lowering the maximum combustion pressure, and as the engine speed and engine load increase, the lift amount is adjusted to the base timing. You can also set it back.

In the above embodiment, the cylinder number control circuit 15,
Although the fuel injection control circuit 20 and the valve timing control circuit 45 are described as being independent, they may also be integrated into a digital computer with the above functions and provided for overall control. Of course it's good.

(Effects of the Invention) Since the present invention is constructed as described above, it is possible to reduce vibrations during cylinder reduction operation and obtain a good operating condition.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is an overall configuration diagram of an engine with cylinder number control, FIG.
5 and 5 are explanatory diagrams of the valve timing of the intake and exhaust valves, and FIGS. 6 to 8 are explanatory diagrams of the valve timing of the intake and exhaust valves of modified examples. 1A, 1B, 1C, 1D...Cylinder, 2...Intake passage, 11, 12...Shutter valve, 13...
... Negative pressure sensor, 14 ... Rotation speed sensor, 15 ...
Cylinder number control circuit, 27...Intake valve, 28...Exhaust valve, 32...Camshaft, 33...Cam, 34
...Variable timing mechanism.

Claims (1)

[Claims] 1. A first cylinder group that suspends operation during specific operations,
In a cylinder number controlled engine having a second cylinder group that is constantly activated, a control means is provided for controlling the valve timing of the second cylinder group in a direction in which the maximum combustion pressure is lower during reduced-cylinder operation than during full-cylinder operation. A cylinder number control engine featuring the following features: