JPS58152139A - Control of internal-combustion engine - Google Patents

Abstract

PURPOSE:To make it possible to operate an engine as a two-cycle engine when the engine load is high and to operate it as a four-cycle engine when the engine load is low by a method wherein the frequency of opening and closing operations of each of an intake valve and an exhaust valve is varied in accordance with the operation condition of the engine provided with a supercharger. CONSTITUTION:When an internal-combustion engine provided with a supercharger 17 is operated with low load or at low speed, an intake valve 13 and an exhaust valve 15 of the engine are opened and closed once every two rotations of the engine functioning as a four-cycle engine, while when the engine is operated with high load or at high speed, the valves are opened and closed once every single revolution of the engine functioning as a two-cycle engine, in the timing shown in the drawing. In this case, an ignition plug 16 is supplied with an ignition current every time when the piston comes near its top dead center. As a result, the combustion of the engine is stabilized when the engine is operated with low load, while when it is operated at high speed, the output thereof increases and the rotation thereof becomes smooth.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention I/'i relates to a control technique for an internal combustion engine, and particularly relates to a control device for an internal combustion engine that switches between 2-cycle and 4-cycle operating sounds depending on the engine operating state.

Figure 1 shows the operating principle of a conventional two-stroke engine (
Literary Automatic Engineering Engine Edition P280 Sankaido S 42
．． Published on 12.25). In (4), since the intake port 1 is open, the air-fuel mixture is sucked into the crank chamber 2, while the piston 4 descends due to combustion of the air-fuel mixture ignited by the first spark plug 3. The descending piston 4 closes the @2 port 1, and before the piston 4 reaches the bottom dead center, the exhaust port 5 is opened as shown in (B), and the combustion gas is discharged. Subsequently, the scavenging port 6 is opened, and the air-fuel mixture with a crank note of 2 yen is (C).
The scavenging air is sent into the combustion chamber through the scavenging port 6. The piston 4, which reverses and rises at the bottom dead center, is connected to the scavenging port 6. Close the exhaust port 5 and mix the combustion guide? Compress as in (2). Before the piston 4 reaches top dead center, it opens to the intake port 1', and then returns to the previous round, and the cycle is repeated.

Therefore, a 2-stroke engine, which completes one cycle in one engine per revolution, can omit one rotation of the engine for intake and exhaust in a 4-stroke engine, so when compared at the same rotation speed, a 2-stroke engine has a scavenging efficiency of 75%. At full load, the maximum output is 30 to 40 inches higher than that of a four-cycle engine. That is, in high-speed operating ranges and under heavy loads, the two-stroke engine has better maximum output and torque stability.

However, the conventional 2? In a 2-cycle engine, when the suction capacity is reduced during low-speed operating ranges or partial loads, the residual gas percentage tends to increase, and when compared to idling, the percentage of residual gas increases to about 90% in a 2-cycle engine.

On the other hand, in a 4-cycle engine, it is about 50%. Therefore, a four-cycle engine has better combustion in low-speed operating ranges or under partial load.

Does the present invention provide pulp opening/closing timing for intake and exhaust valves? We focused on the fact that by simply switching, it becomes a 2-stroke engine or a 4-cycle engine, and in low-speed operating ranges or partial loads, it operates as a 4-stroke engine for stable combustion, while in high-speed operating ranges or under high loads, it operates as a 2-stroke engine. It is an object of the present invention to provide a control system that achieves maximum output and smooth engine rotation by stabilizing the torque of the output shaft.

Hereinafter, one embodiment of the present invention will be explained based on the drawings. Figure 2 shows the suction;
Pulp opening/closing timing of the exhaust valve Fig. 4 is a diagram of the principle of operation when the engine is operated as a four-cycle engine. In the figure 11
is a piston that performs reciprocating sliding movement within the cylinder 10. Is the ignition current every time at the optimum ignition position near the upper part KVi of the cylinder 10 and the piston top dead center? The ignition plug 16 connected to the supply ignition device and the intake and exhaust ports 12 and 14
Suction and exhaust valves 13 and 15 for opening and closing are provided.

An intake compressor 17A of a turbocharger 17 is installed in the intake port 12, and is driven by an exhaust turbine 17B installed in the exhaust port 14.

Intake air is forced into the intake port (intake port) 12.

(The turbocharger 17 is completely omitted in FIG. 2.) Next, the pulp opening/closing timings of the intake air 9P13 and the exhaust air 7P15 are changed widely depending on the operating conditions.

In the low-speed operating range of the engine, the crankshaft operates as a 4-cycle engine, that is, it opens and closes once every two rotations of the crankshaft, as shown in Figure 3, and in the high-speed operating range, it functions as a Fi 2-cycle engine. 1 per rotation of
Each turn is opened and closed at the timing shown in Figure 5.
controlled as follows.

The driving device for the suction/exhaust box 1315 for this purpose is shown in Figures 6 and 7 (however, only the side of the air box 13 is shown).
18 is a camshaft 19 which is rotated in synchronization with the crankshaft (rotated and connected to the piston 11 in FIGS. 2 and 4);
(rotates once for every 2 rotations of the engine) The intake valve 13 is urged upward (in the valve opening direction) by the spring 20 through the rocker arm 21, against the spring 20. Move it downward to open the 12 intake boats shown in Figures 2 and 4. The rocker arm 21 is loosely inserted into a rocker shaft 22 parallel to the camshaft 19 with both ends thereof in contact with the circumferential surface of the cam 18 and the upper end of the stem of the intake valve 13, respectively. As it rotates clockwise, it swings according to its profile and moves up and down the five intake squares 13.

By the way, the cam 18 is composed of a pair of cams 23 and 24, each having a different cam profile.
In the figure, cam 23Fi is shown on the paper.

Is there a profile for a 2-stroke engine that has two lift parts and lifts the intake box 13 once per rotation of the machine rjA as shown in Figure 3? The cam 24F'i is on the front side of the page.

As shown in Fig. 5, the engine rotates once and the engine ff 3 k I
It has a profile for a 4-stroke engine with a J aft.

On the other hand, the rocker arm 21 has a coil spring 26 elastically mounted between it and a bracket 25 that pivotally supports the rocker shaft 22. A control ring 27 that is loosely inserted into the rocker shaft 22 on the opposite side of the coil spring 26
The coil spring 28 is elastically mounted between the coil springs 26 and 28, and the same axial position is maintained by the balance of the elastic forces of the coil springs 26 and 28. An actuating rod 30 of an actuator 29, such as a hydraulic cylinder, is connected to the control ring 27. The actuating rod 30 is loosely supported by a bracket 31 for supporting the rocker shaft 22, and the actuator 29 is connected to the operating state of the engine (rotational speed,
By detecting the engine load), the control ring 27 is activated via the operating port RAD 30 when the engine is operating at high speed or under high load.
is moved from the position (■) in FIG. 6, which is the position in the low speed operating range or under low load, to the protruding position shown in Q).

The width of the cam side end 21a of the rocker arm 21 is approximately equal to the thickness and the same axial length of the cams 23 and 24, and the width of the intake valve side end 21b is approximately twice that. has been done.

Although the drive device for the exhaust gas 9P15 is not particularly shown, it is shared by the camshaft 19, the rocker shaft 22, and the actuator 291 that operates by detecting the engine operating state, and the rest has the same configuration as the drive device for the intake valve. be. That is, a pair of cams for exhaust valves with different cam profiles are provided;
Exhaust once per rotation* 15k! It has a profile for a 2-stroke engine that allows J-aft, and the other one has a profile for a 2-stroke engine that makes 1
Recycle exhaust 9P15' (has a profile for a 4-cycle engine to be lifted (see Figures 3 and 5)
The actuator 29Fi moves the control ring 27 to the position in the low speed operating range or under low load based on the detected values of the rotation speed sensor 35 and load sensor 36, which serve as operating state detection means, and a signal from the control circuit 37. ■
The valve opening/closing timing should be maintained at 11.1 in all cases as shown in Figure 3, and in high-speed operating ranges and high loads. Similarly, the pulp opening/closing timing is controlled to be as shown in FIG. 5 while maintaining the state of 1 position (3).

According to this configuration, when one engine is operating at a low speed or under low load, the actuator 29 does not operate and the control ring 27 is placed in the position 2 in FIG. 6 due to the operation control 30. Therefore, due to the balance between the springs 26 and 28, the rocker arm 21 is placed in an axial position where the cam side end 21a contacts the circumferential surface of the cam 240 for a four-cycle engine as shown in FIG. 6, and swings according to the profile of the cam 24. Then, the intake valve 13 is opened and closed. Similarly, the exhaust valve 15 also opens and closes in accordance with the current force profile for a four-stroke engine. Since the pulp opening/closing timing of the intake and exhaust valves 13 and 15 at this time is set as shown in FIG. 3, one engine operates as a four-cycle engine shown in FIG. 2.

That is, when the piston 11 begins to descend from top dead center,
The intake valve 13 is opened as shown in FIG. 2(a) (at this time, the exhaust valve 9P15 is closed as shown in FIG. 3).

The air-fuel mixture is sucked into the cylinder 10 through the intake boat 12. When the piston 11 reaches the bottom dead center, it reverses and rises,
Shortly, the intake air 9P13 is closed, and thereafter the air-fuel mixture is compressed as shown in FIG. 2(b). When the piston 11 is near the top dead center, a high voltage ignition current is supplied to the ignition plug 16 by the ignition device to ignite, and the pressure rises by 10 yen in the cylinder due to combustion of the mixture, resulting in the rise in temperature shown in Fig. 2 (C). As such, the piston 11 descends. Before the piston 11 reaches the bottom dead center again, the third
The exhaust valve 15 opens as shown. Since the piston 11 reverses at the bottom dead center and rises, the combustion gas h
mkiho) is discharged from 14. In addition, piston 1
1 rises, just before top dead center (in Figure 3).

When the exhaust valve 15Fi is open and the exhaust valve 13 is still closed, the ignition device supplies the entire ignition current to the ignition plug 1.
6 ignites again, but 1 ignition is performed on the gas after combustion, so it does not affect the operation of the 4-cycle engine. In addition, during 4-cycle operation, if the ignition current is supplied only for the explosion stroke, once every two revolutions, there is no need to consume extra ignition energy. After that, intake valve 1
3 opens and the piston 11 reaches top dead center. Thereafter, the piston 11 begins to move downward, moving to the second suction stroke shown in FIG. 2(a), and the cycle is repeated.

On the other hand, when one engine is operating at high speed or under high load.

The actuator 29 is actuated by a drive signal from the control circuit 37 and is connected to the control ring 2 via the actuating rod 30.
7. Move to the position marked ■ in Figure 6.

As a result, the balance position of the springs 26 and 28 is moved upward in the figure, and as a result, the cam side end 21a of the rocker arm 21 comes into contact with the circumferential surface of the cam 23 for the two-cycle engine. Therefore, the rocker arm 21 swings according to the profile of the cam 23, and opens and closes according to the intake air -ffl 3'.

Similarly, the exhaust valve also swings according to the profile of the cam for a two-stroke engine, and the exhaust valve 15 is fully opened and closed. This time, the pulp opening/closing timing of the intake and exhaust valves 13 and 15 follows the timing shown in FIG. 5, and the engine operates as a two-cycle, cycle engine as shown in FIG.

That is, the piston 11 descends, and on the way down, the exhaust gas 9P
15. Subsequently, [phase] air-7P13 opens as shown in FIG. At the same time as the intake air 13 opens, the turbocharger 17 pumps (supercharges) the p@ air and the combustion gas flows into the exhaust boat 14.
pushed out more. This scavenging.

Even at the stage where the piston 11 reverses at the bottom dead center and rises, the process continues as shown in FIG. 4(a). Thereafter, the exhaust valve 15 is closed, followed by @9f13', and the compression stroke begins.

1 ignition current when piston 11 comes before top dead center? The ignition plug 16 is ignited by the supplied ignition device, the compressed air-fuel mixture is ignited, and the piston 11 is reversed at the top dead center.
As shown in b), the piston 11 descends due to the increase in pressure due to combustion. While the piston 11 is descending, exhaust 9F15. Next, the intake valve 1/3 is opened and the intake (scavenging) stroke begins, and the cycle is repeated thereafter.

Furthermore, since the rocker arm 21 is supported by the rocker shaft 22 by springs 26 and 28, when the rocker arm 21 is being driven by the cam 24, the control ring 27 can be moved as the actuator 29 operates.
Even if the rocker arm 21 and cam 2 are moved from
4 and the rocker arm 21 due to friction with the stem of the intake section 13.

The coil spring 28 is only compressed and held in the same position, and then the side end 21a of the rocker arm 21 is moved to the cam 24.
When the rocker arm 21 moves from the lift section to the base circle, the rocker arm 21 moves to the ■ position and comes into contact with the cam 23. Further, the action of the rocker arm 21 returning from the position ◯ to the position ◯ in Fig. 6 is completely opposite, and its explanation will be omitted.

Further, although the turbocharger 17 is operated when the engine is a two-stroke engine that produces high output, it may also be operated when the engine is a four-cycle engine. (In addition, 4
To stop the operation of the turbocharger 17 during cycle IFM@5 operation, 1, for example, provide an exhaust bypass passage to bypass the exhaust pressure to the turbine 17B' and release it. As described above, according to the present invention, depending on the operating state of the engine, @, the opening and closing of the exhaust valve, 4? in the low speed operating range, or at low load. Once for every 2 engine revolutions, once for each engine revolution in high speed operating range or high 9 load.
In order to ensure that the ignition current is supplied to the ignition plug each time near the top dead center of the piston, the 4-stroke engine can stabilize combustion and improve fuel efficiency during low speed operation or low load. The characteristics of the Fi2 cycle engine provide the same effect in terms of output and smooth engine rotation in high-speed operating ranges or high loads.

Figures 2 (IL) to (d) are diagrams of the operating principles of a four-stroke engine according to the present invention, and Figure 3 is an explanation showing the pulp opening/closing timing of the intake and exhaust valves in the same four-stroke engine. Figure 4 (a), (bl is a diagram of the operating principle when the two-stroke engine of the present invention is used, and Figure 5 is an explanatory diagram showing @ and the pulp opening and closing timing of exhaust exhaust when the same two-stroke engine is used. , FIG. 6 is a plan view showing the drive device for the intake section, and FIG. 7 is an exploded view showing the drive device &.

12...Intake boat, 13...Intake portion, 14...
Exhaust boat, 15... Exhaust valve, 16... Spark plug, 1
7...Turbocharger, 18,23.24...Cam, 21...Rocker arm, 22...Rocker shaft S 26°28...Spring, 29...Actuator, 35...Rotational speed Sensor %36...Load sensor, 37...Control circuit.

Patent applicant: Nissan Automatic Wataru Co., Ltd.
(PJP ki) (C)
(D) Figure 2 (a) Figure 2 (b) Figure 2 (c) Figure 2 (d) Figure 3 Figure 5 Figure 4 (a, Figure 6)

Claims (1)

[Scope of Claims] In an internal combustion engine equipped with a supercharger that supercharges intake air, intake and exhaust valves that open and close in synchronization with one engine rotation speed, and a spark plug that ignites and burns the intake air-fuel mixture, one engine rotation A means to check the operating status of the number, square cargo, etc. A variable drive device that switches the intake and exhaust valves at predetermined timing to open and close the intake and exhaust valves depending on the operating condition, once every two engine revolutions in low-speed operating ranges, and once per engine revolution in high-speed operating ranges. . A control device for an internal combustion engine equipped with an ignition device that supplies a wide current to the spark plug near the top dead center of the piston.