JPH0364649A - Control device of engine with mechanical supercharger - Google Patents

Abstract

PURPOSE:To relax the torque shock when the load is varied by controlling to increase the compression ratio and delay the closing time of a suction valve in a low load area, to advance the closing time of the suction valve when the engine load is increased, and to reduce the compression ratio when the engine load is increased further. CONSTITUTION:In a piston 38 installed in a cylinder 36, the upper end 42a of a connecting rod 42 is connected to a piston pin 40 in which a projection 40a to compose a compression ration converting device 70 is formed at the middle part, and the volume of the combustion chamber 12 (the compression ratio) is different when the projection 40a is positioned at the upper side and when it is positioned at the lower side. A suction port 14 facing the combustion chamber 12 is opened or closed by a suction valve 14a whose closing time is variable by a closing time converting device 62. In this case, by using a control device 72, the system is controlled to increase the compression ratio and delay the closing time of the suction valve 14a in a low load area, to advance the closing time of the suction valve 14a when the engine load is increased, and to reduce the compression ratio when the engine load is further increased.

Description

DETAILED DESCRIPTION OF THE INVENTION 1. Field of Industrial Application The present invention relates to a control device for a mechanical supercharged engine.

``Prior art and problems to be solved by the invention'' Conventionally, a device for variable control of the compression ratio of the combustion chamber of an engine according to the engine speed and engine load was developed in 1988-1925.
It is shown in Publication No. 41. The device disclosed in this publication variably controls the compression ratio of the engine's combustion chamber, but it not only controls the compression ratio of the intake air introduced into the engine's combustion chamber, but also controls the closing timing of the intake valve. It is possible that A device for controlling the compression ratio of the combustion chamber and the closing timing of the intake valve in this manner will be described below.

First, in the low load range of the engine, the compression ratio of the combustion chamber is increased to improve fuel efficiency, and the closing timing of the intake valve is delayed to return a portion of the intake air to the intake passage. , the amount of intake air is reduced to reduce pumping loss. Note that in a low load region, knocking does not occur, so the compression ratio of the combustion chamber can be increased.

On the other hand, in the high load region of the engine, the compression ratio of the combustion chamber is lowered and the intake valve close timing is advanced (here, "early opening" is used to compare with the above-mentioned "late closing"). (refers to the normal closing timing) increases the amount of intake air and increases the torque. Note that in high load regions, the compression ratio of the combustion chamber is lowered to prevent knocking.

When applying the device that controls the compression ratio of the combustion chamber and the closing timing of the intake valve as described above to a mechanically supercharged engine,
There are the following problems. In other words, when the engine transitions from a low load area to a high load area or when the engine transitions from a high load area to a low load area, the switching line for the compression ratio of the combustion chamber and the switching line for the closing timing of the intake valve are set to the same line. If it is set to , two switchings occur at the same time, resulting in a problem of large torque shock.

An object of the present invention is to provide a control device for an engine equipped with a mechanical supercharger that can improve fuel efficiency in a low load region of the engine and improve torque in a high load region while alleviating torque shock during load fluctuations. It is about providing.

"Means for Solving the Problems" The present invention comprises: a mechanical supercharger; an intake port that introduces intake air supercharged by the mechanical supercharger into a combustion chamber of an engine; and an intake port that opens and closes the intake port. an intake valve; a closing timing changing means for changing the closing timing of the intake valve; a compression ratio changing means for changing the compression ratio of the intake air introduced into the combustion chamber; a load detecting means for detecting the load of the engine; and a control means for controlling the closing timing changing means and the compression ratio changing means based on the detection signal from the load detection means, the control means controlling the engine based on the detection signal from the load detection means. In low load areas, the compression ratio of the combustion chamber is increased,
In addition, the intake valve closing timing is delayed, and when the engine load increases, the intake valve closing timing is advanced, and when the engine load further increases, the compression ratio of the combustion chamber is reduced. shall be.

"Function" In the present invention, in the low load region of the engine, the compression ratio of the combustion chamber is increased and the closing timing of the intake valve is delayed.When the engine load increases, the closing timing of the intake valve is first delayed. If the engine load increases further, the compression ratio of the combustion chamber decreases. In this way, the switching line for the combustion chamber compression ratio and the switching line for the intake valve closing timing are set separately, so the two switchings do not occur at the same time, but are performed at a time lag, making it easier to switch between the two when the load fluctuates. torque shock can be alleviated.

Here, when the engine load increases, the closing timing of the intake valve is first changed, and then when the engine load increases further, the compression ratio of the combustion chamber is changed for the following reasons. .

If the compression ratio of the combustion chamber is first changed when the engine load increases, and then the intake valve closing timing is changed when the engine load further increases, then When the amount of intake air increases, the closing timing of the intake valve must be changed, and the amount of intake air increases rapidly, causing torque shock.

Additionally, if the closing timing of the intake valve is earlier, the opening timing of the intake valve will also be earlier, and the time overlapping with the open state of the exhaust valve will be longer, so more exhaust gas will be discharged by intake ( (so-called improved scavenging efficiency), which results in a sharp increase in torque. Therefore, if the intake valve closing timing is changed in this manner when the engine is under high load and the amount of intake air is increased, fluctuations in torque shock become particularly noticeable.

For the above reasons, when the engine load increases,
The closing timing of the intake valve is changed, and then when the engine load increases further, the compression ratio of the combustion chamber is changed.

"Embodiments" Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 1 shows a control device for a mechanical supercharged engine according to an embodiment of the present invention.

In FIG. 1, reference numeral 10 indicates a DOHC type mechanical supercharged engine, and the engine 10 has a combustion chamber 12. As shown in FIG. The combustion chamber 12 is provided with an intake port 14 and an exhaust port 16, and the intake port 14 and exhaust port 16 are opened and closed by an intake valve 14a and an exhaust valve 16a, respectively.

Note that the exhaust port 16 is open to the atmosphere via an exhaust passage 17.

Reference numeral 18 indicates a mechanical supercharger, and the mechanical supercharger 18
communicates with the intake boat 14 via an intake passage 20, and a surge tank 22 is provided in the middle of the intake passage 20.
, a fuel injection valve 23 is arranged. Further, the mechanical supercharger 18 is open to the atmosphere through an intake passage 24, and an air cleaner 26, an air flow meter 28, and a throttle valve 30 are arranged in the middle of the intake passage 24.

Note that the intake passage 20 and the intake passage 24 are connected by a bypass passage 32, and a control valve 34 is disposed in the bypass passage 32. When the mechanical supercharger 18 is stopped, the control valve 34 is opened. It is opened to allow intake air to be introduced into the combustion chamber 12 via the bypass passage 32.

In the engine 10, the reference numeral 36 indicates a cylinder, and a piston 38 is disposed within the cylinder 36 so as to be slidable in the vertical direction. A piston pin 40 is disposed within the piston 38, and the piston pin 40 has an upper end of a connecting rod 42 (not shown in FIG. 1).
The lower end of the connecting rod 42 is pivotally supported by a crankshaft 44.

A crank pulley 46 is attached to this crankshaft 44, while a drive shaft 4 of the mechanical supercharger 18 is attached to the crankshaft 44.
A driven pulley 50 is attached to 8, and a belt 52 is stretched around the driven pulley 50 and the crank pulley 46, so that the rotation of the crankshaft 44 operates the mechanical supercharger 18. ing. In addition, an electromagnetic clutch 54 is installed in the middle of the drive shaft 48 of the mechanical supercharger 18.
is arranged, and the mechanical supercharger 18 is operated or stopped by engaging or disengaging the electromagnetic clutch 54.

The intake valve 14a1 and the exhaust valve 16a are the cam 56a of the intake camshaft 56 and the exhaust camshaft 5, respectively.
It is opened and closed at a predetermined timing by the No. 8 cam 58a. Here, the closing timing of the intake valve 14a is changed by a closing timing changing means, and this closing timing changing means will be explained below.

The rotation of the engine crankshaft 44 is transmitted to the large gear 60 via a power transmission means (not shown). This large gear 60 and intake camshaft 56
are connected by closing timing changing means 62,
This closing timing changing means 52 includes a helical gear portion 64 formed coaxially with the large gear 60, a helical gear 866 formed at the end of the camshaft 56, and both gear portions 6.
4.66 and an axially movable annular body 68.

Then, by moving the annular body 68 in the axial direction,
The rotational phase of the camshaft 56 relative to the large gear 60 changes, thereby changing the phase of the cam 56a and changing the closing timing of the intake valve 14a.

Next, the engine 10 includes compression ratio changing means for changing the compression ratio of intake air introduced into the combustion chamber 12. below,
This compression ratio changing means will be explained with reference to FIGS. 2A and 2B.

Reference numeral 42a indicates the upper end of the connecting rod 42, and the upper end 42a is coupled to the piston pin 40. The piston pin 40 is not completely cylindrical, but has a convex portion 4 in the middle that constitutes the compression ratio changing means 70.
ua is formed (see 2nd Δ, 2B).

Therefore, the position of the piston 38 is a distance i? between when the convex portion 40a of the piston pin 40 is located above (FIG. 2A) and when it is located below (FIG. 2B). The difference is ltL, that is, the volume of the combustion chamber 12 is different. Therefore, when the convex portion 40a of the piston pin 40 is located upward (FIG. 2A), the volume of the combustion chamber 12 is large, so the compression ratio of the intake air introduced into the combustion chamber 12 is small. On the other hand, when the convex portion 40a of the piston pin 40 is located downward (FIG. 2B), the volume of the combustion chamber 12 is small, so the compression ratio of the intake air introduced into the combustion chamber 12 is large.

Note that the position of the convex portion 40a is changed by rotating the piston pin 40 while the piston 38 is in operation. here,
Piston pin 40 is rotatable relative to piston 38. The lock pin 43 disposed in the hole 42b of the connecting rod 42 is engaged with the engagement hole 40b or 40c of the piston pin 40 by the hydraulic pressure of the hydraulic passage 42c, thereby maintaining the position of the protrusion 40a.

Next, in FIG. 1, reference numeral 72 indicates a control means for controlling the closing timing changing means 62 and the compression ratio changing means 70. Further, reference numeral 74 is a load detection means for detecting the load of the engine, and the load detection means 74 is composed of an opening sensor of the throttle valve 30.
is a rotation speed detection means for detecting the rotation speed of the engine. The control means 72 controls the closing timing change means 62 and the compression ratio change means 70 based on the detection signal from the load detection means 74 and the detection signal from the rotation speed detection means 76.

Hereinafter, the control of the closing timing changing means 62 and the compression ratio changing means 70 by the control means 72 will be explained with reference to the control map shown in FIG.

First, in the low load region of the engine, the compression ratio of the combustion chamber 12 is increased to improve fuel efficiency, and the closing timing of the intake valve 14a is delayed to divert a portion of the intake air once introduced to the intake passage 20.
This reduces the amount of intake air and reduces pumping loss. On the other hand, in a high load region of the engine, the compression ratio of the combustion chamber 12 is lowered to prevent knocking, and the closing timing of the intake valve 14a is advanced to increase the amount of intake air and torque.

Here, when transitioning from a low load region to a high load region, the switching of the compression ratio of the combustion chamber and the switching of the closing timing of the intake valve are not performed at the same time, but are performed with a time lag. In other words, in the low load region of the engine, the compression ratio of the combustion chamber is increased and the closing timing of the intake valve is delayed. When the engine load increases, the closing timing of the intake valve is first advanced, and then the engine As the load increases further, the compression ratio of the combustion chamber is reduced.

In this way, the switching line for the combustion chamber compression ratio and the switching line for the intake valve closing timing are set separately, so the two switchings do not occur at the same time, but are performed at different times.
Torque shock during load fluctuations can be alleviated.

Here, when the engine load increases, the closing timing of the intake valve is first changed, and then when the engine load increases further, the compression ratio of the combustion chamber is changed for the following reasons. .

If the compression ratio of the combustion chamber is first changed when the engine load increases, and then the intake valve closing timing is changed when the engine load further increases, then When the amount of intake air increases, the closing timing of the intake valve must be changed, and the amount of intake air increases rapidly, causing torque shock.

Additionally, if the closing timing of the intake valve is earlier, the opening timing of the intake valve will also be earlier, and the time overlapping with the open state of the exhaust valve will be longer, so more exhaust gas will be discharged by intake ( (so-called improved scavenging efficiency), which results in a sharp increase in torque. Therefore, when the intake valve closing timing is changed as described above when the engine is under high load and the amount of intake air is large, fluctuations in torque shock become particularly noticeable.

For the above reasons, when the engine load increases,
The closing timing of the intake valve is changed, and then when the engine load increases further, the compression ratio of the combustion chamber is changed.

[Effects of the Invention] As explained above, according to the present invention, it is possible to improve fuel efficiency in the low load region of the engine and improve torque in the high load region, while alleviating torque shock during load fluctuations. can.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the configuration of a control device for a mechanical supercharged engine according to an embodiment of the present invention, FIGS. 2A and 2B are explanatory diagrams of the configuration of a compression ratio changing means, and FIG. FIG. 2 is a control map diagram of a mechanically supercharged engine according to an embodiment of the invention. 10...Engine, 12...Combustion chamber, 14...Intake boat, 14a...Intake valve, 16...Exhaust port, 16a ...Exhaust valve, 18...Mechanical supercharger, 17...Exhaust passage, 20.24...Intake passage, 36...・Cylinder, 38... Piston, 40... Piston pin, 42... Connecting rod, 4...
・Crankshaft, 6.58...camshaft, 6a, 58a...cam, 2...closing timing changing means, 0...compression ratio changing means , 2... Control means, 4... Load detection means, 6... Rotation speed detection means.

Claims (1)

[Scope of Claims] A mechanical supercharger, an intake port that introduces intake air supercharged by the mechanical supercharger into a combustion chamber of an engine, an intake valve that opens and closes the intake port, and the intake valve. a closing timing changing means for changing the closing timing of the combustion chamber; a compression ratio changing means for changing the compression ratio of the intake air introduced into the combustion chamber; a load detecting means for detecting the load of the engine; and from the load detecting means. control means for controlling the closing timing changing means and the compression ratio changing means based on the detection signal from the load detection means, the control means controlling the combustion chamber in a low load region of the engine based on the detection signal from the load detection means. Increase the compression ratio of
In addition, the intake valve closing timing is delayed, and when the engine load increases, the intake valve closing timing is advanced, and when the engine load further increases, the compression ratio of the combustion chamber is reduced. A control device for an engine with a mechanical supercharger.