JPS60150406A - Cylinder number controlling engine - Google Patents

Abstract

PURPOSE:To reduce vibration caused by variation in engine torque by adjusting the timing or the amount of lift of an intake valve so that the combustion pressure of operating cylinders is reduced when operating an engine with the number of cylinders reduced. CONSTITUTION:At the time of idling in an area, in which the number of cylinders is reduced, the closing timing of an intake valve is made delay later than the base timing, a slight blow-back of air occurs, charging efficiency is reduced, and combustion pressure is reduced, in a first and a second cylinder which continue to operate, causing variation in torque to be less, and the vibration of engine to be reduced. The closing timing of the intake valve may be made delay not only at the time of idling but also in the whole area at the time of operation with reduced cylinders. It is also possible to reduce vibration by advancing the closing timing of the intake valve earlier than the base timing, and increasing the amount of overlapping. A similar end can also be achieved by reducing the amount of lift of the intake valve.

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 during a specific operation such as when the engine is under light load and performs reduced-cylinder operation.

(Prior art) Conventionally, since fuel efficiency tends to be better during high-load operation, in a multi-cylinder engine, when the engine load is small, fuel supply to the negative cylinder is canted to stop operation. A cylinder number control engine is known that performs cylinder reduction operation so as to relatively increase the load on the remaining operating cylinders by this amount and improve overall fuel efficiency in the light load range (for example, Japanese Patent Application Laid-Open No. 57-338 reference).

However, since such engines are controlled with the same valve timing both when operating with reduced cylinders and when operating with all cylinders, the cycle time is long and charging efficiency is reduced due to only one explosion per revolution of the crankshaft. Since the combustion pressure is high, the 1 to 1 torque fluctuation is large, which is disadvantageous to vibration compared to when all cylinders are operated. The present invention attempts to reduce vibration by changing valve timing.

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

(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.

(Configuration of the Invention) In order to achieve the above-mentioned object, the configuration of the present invention is to provide a cylinder number controlled engine having a first cylinder group that is inactive during a specific operation and a second cylinder group that is constantly activated. The present invention is characterized in that 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.

(Example) Embodiments of the present invention will be described below based on the drawings.

The engine 1 shown in FIGS. 1 and 2 has a first cylinder group (second and third cylinders IB and IC) that is inactive during a specific operation.
and the second cylinder group (first and fourth cylinders IA
, ID) is a four-cylinder cylinder number control engine.

In Fig. 1, reference numeral 2 denotes an intake passage, from the upstream side an air cleaner (not shown), an air flow sensor 3, and a fuel injection valve 4.
and a main intake passage 6 in which a throttle valve 5 is arranged in order, and each cylinder IA, IB, branched from the main intake passage 6,
Four branch intake passages 7, 8, leading to the combustion chambers of IC and ID.
It consists of 9.10.

Branch intake passage 8 for the second and third cylinders IB and IC
, 9 are respectively provided with shutter valves 11 and 12, which output a negative pressure signal Sl corresponding to the intake negative pressure from the negative pressure sensor I3 and a rotation speed signal corresponding to the engine rotation speed from the rotation speed sensor I4. s2, as shown in FIG. 3, when the cylinder number control circuit 15 determines that the intake negative pressure is equal to or less than the set intake negative pressure Pm and the set engine rotation speed is equal to or less than the set engine speed Nm, the actuator 16 (for example, the electromagnetic solenoid 1 to is activated, shutter valves 11 and 12 are closed, and cylinder reduction operation is performed.

I7 is the exhaust passage for each cylinder], A, IB, IC, II]
It is branched into four branch exhaust passages leading to the combustion chamber.

A water temperature sensor 18 outputs a temperature signal S3'lt 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, another signal Sl , regardless of S2.

It is designed to perform all-cylinder operation. A throttle opening sensor 19 is connected to the throttle valve 5, inputs a slot opening signal S4 to the cylinder number control circuit 15, and performs all-cylinder operation during acceleration.

20 is a fuel injection control circuit which receives an intake air quantity signal S5 from a potentiometer 45 linked to the air flow sensor 3;
is input, a fuel injection amount corresponding to the intake air amount is determined, and a pulse signal S6 corresponding to the amount is sent to the fuel injection valve 4.

In FIG. 2 showing the first cylinder IA of the engine shown in FIG. 1, 21 is a cylinder block, on the upper side of which a cylinder head 23 is provided via gaskets 1-22. 24 is a combustion chamber.

Reference numerals 25 and 26 denote an intake port and an exhaust port i~, 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 each slidably supported on the cylinder head 23 via valve guides 29, 29, and are constantly biased upward, that is, in the valve closing direction, by valve springs 30, 30. There is.

At the top of the cylinder head 23, there is an intake and exhaust valve 27°2.
8, an intake-side and exhaust-side valve mechanism 31A that controls the opening and closing of
31B is provided. The intake side and exhaust side valve mechanisms 31A, 31B are connected to the engine crankshaft (
It has intake side and exhaust side camshafts 32A and 32B that are rotationally driven by a camshaft 3 (not shown).
Cams 33A and 33B are formed in 2A and 32B in correspondence with the intake and exhaust valves 27 and 28, so that the opening and closing of the intake and exhaust valves 27 and 28 are controlled by the rotation of the camshafts 32A and 32B. There is.

Further, the intake side valve operating mechanism 31Δ includes a variable timing mechanism 34 that variably controls the valve timing of the intake valve 27.
is provided. The variable timing mechanism 34 includes a tappet 35 interposed between the cam 33A and the valve stem 27a of the intake valve 27, a fitting hole 36a into which the tappet 35 is slidably fitted and held, and a circular ring of the cylinder head 23. Lower surface 36b formed in an arc shape corresponding to the arc-shaped inner surface
and a rotary member 36 that is rotatably supported on the intake camshaft 32A, and the rotary member 36 is rotated between the intake side force shafts 1 to 32A according to the operating state of the engine.
and an operating means 37 for rotating about the rotation center.

The rotating member 36 is divided into upper and lower members 36c and 36d at a portion supported by the intake camshaft 32A, and are integrally connected at a port 1-38.38.

Further, the operating means 37 has a rotating shaft 39 connected to the upper member 33c of the rotating member 36 of the variable timing mechanism 34, and a rotating shaft 39 that is disposed perpendicular to the rotating shaft 39 and connected to the rotating shaft 39. The reciprocating shaft 40 is engaged with the reciprocating shaft 40 and is capable of reciprocating in the left-right direction in FIG. A driving means 41 for rotating the rotating member 36 as described above via the shaft 39 is provided.

When the intake side force shaft 1-32A rotates and the cam 33 presses the pressure receiving part 35a of the tappet 35, and the tappets 1 to 35 are pushed down inside the insertion hole 36a, the intake valve 27 is moved by the valve spring. The intake port 25 is opened by being pushed down by the suppressing portion 35b of the tappet 35 against the urging force of the tappet 30.

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 determines the valve timing of the intake valve 27 according to the negative pressure signal S1 and the engine speed signal S2, and drives the drive means 41 with a corresponding drive signal S7. . 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 and the exhaust valve 2 are closed during regular operation, including during light load in the all-cylinder operating range of the engine.
8 are controlled to open and close at predetermined valve timings by an intake side valve mechanism 31A and an exhaust side valve mechanism 31B, respectively. That is, as shown by the solid line in FIG.
8 opens a little before the piston's bottom dead center (13IDC) and then closes near the top dead center (TDced), while the intake valve 27 opens near the piston's second dead center and closes a little later than the dead center. Controlled by base timing.

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 in the counterclockwise direction to change the opening timing of the intake valve 27 to the side delayed from the base timing. The outflow of exhaust gas to the exhaust passage 17 is promoted, and the introduction of fresh air in the next stroke is promoted using the intake inertia force due to the increase in the amount of intake air, thereby increasing the filling efficiency.

During idling operation in the reduced cylinder operation range.

In the first and fourth cylinders IA and ID that operate, the intake valve 27
Since the closing timing is delayed from the base timing, some blowback of intake air occurs, lowering the charging efficiency and lowering the effective compression ratio. Therefore, there is no need to increase the maximum combustion pressure and increase torque fluctuations, so vibrations can be reduced and a good operating condition similar to when all cylinders are operated 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, during cylinder reduction operation, the opening timing of the intake valve 27 is delayed from the base timing only during special 1: idle operation with severe vibration. The closing timing of 27 may be delayed.

``In addition to the second embodiment, as shown by the solid line in FIG. 6, the opening timing of the intake valve 27 is made earlier than the base timing.''
It is also possible to move the combustion engine earlier than the second dead center and increase the overlap period of the intake and exhaust air -jf21 and -2B, thereby causing slow combustion and lowering the maximum combustion pressure, thereby reducing vibration.

Further, a well-known means for changing the pulses 1 to m can also be used. That is, as shown in FIG. 7, in the all-cylinder operation region, the lift amount is increased at high load compared to the normal operation, that is, the base timing, and the closing timing of the intake valve 27 is delayed, while in the reduced-cylinder operation region, the lift amount is increased compared to the base timing. As shown in Fig. 8, during idling operation, the lift amount is made smaller than the base timing, the closing timing of the intake valve 27 is brought forward to reduce the pumping loss, and the maximum combustion pressure is reduced to reduce vibration. It is also possible to return the lift amount to the base timing by increasing the engine speed and engine load.

In the above embodiment, the cylinder number control circuit 15, fuel injection control circuit 20, and valve timing control circuit 45 are each described as being independent, but they are integrated into a digital computer with the above functions. However, it goes without saying that it may be provided to perform overall control.

(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 the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is an overall configuration diagram of a cylinder number control engine, FIG. 2 is a vertical cross-sectional view of the first cylinder, and FIG.
The figure is an explanatory diagram of the cylinder reduction operation region, Figs. 4 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. It is. LA, IB, IC, ID-... Cylinder, 2... Intake passage, 11, 1.2-... Shutter valve, 13
... Negative pressure sensor, 14 ... Rotation speed sensor, 15
-...Cylinder number control circuit, 27...Intake valve, 28
・・Exhaust valve, 32--・Cam shirt 1-233...
・Cam, 34...Variable timing mechanism

Claims (1)

[Claims] (1) In a cylinder number control engine that has a first cylinder group that is inactive during a specific operation and a second cylinder group that is always activated, the valve timing of the second cylinder group is changed during reduced-cylinder operation and during all-cylinder operation. An engine with a controlled number of cylinders, characterized in that the engine is equipped with a control means for controlling the maximum combustion pressure in a direction that lowers the maximum combustion pressure.