JPS58167843A - Compression ratio controller of engine with turbosupercharger - Google Patents

Abstract

PURPOSE:To obtain a full output of an engine and improve its fuel consumption, by operating an intake control valve in an intake bypass passage and an exhaust control valve in an exhaust bypass passage respetively in accordance with an operational condition to fully operate a turbine at low speed and low loaded time. CONSTITUTION:An intake bypass passage 20 is formed to a guide cylinder 14 fixedly provided to a hole 13 communicating a combustion chamber 5 to the outside of a cylinder head 4. While the upstream and downstream side passages 37, 38 of a turbine are communicated by an exhaust bypass passage 44. At low loaded operation, the passages 20 and 44 are closed to fully display performance of a turbosupercharger 34, and an engine increases its compression ratio to improve its output and fuel consumption. Simultaneously increased exhaust by the high compression ratio is fully applied to the turbine 35, and the supercharge of a compressor 36 is promoted to obtain further high output.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a compression ratio control device for a turbocharged engine.

Normally, in turbocharged engines, when the compression ratio of the engine is increased, the
The compression ratio is lowered to prevent knocking and engine burnout. Therefore, the turbine cannot be operated sufficiently at low rotation speeds or low loads, resulting in a decrease in engine output and poor fuel efficiency. Therefore, the compression ratio and the supercharging pressure are balanced by preventing the supercharging EE from rising above a predetermined value.

As such, for example,
The one described in Publication No. 53 is known. this is,
A bypass valve that forms a bypass passage that communicates a turbine upstream passage and a downstream passage of a turbocharger, and operates this bypass passage by an intake differential between the turbocharger compressor upstream passage and downstream passage. It opens and closes.

In other words, when the supercharging pressure increased by the turbo supercharger reaches a predetermined pressure, this turbocharged engine opens the bypass passage, reduces the displacement acting on the turbine, and reaches the upper limit of the supercharging pressure. is controlled at a constant level.

However, such conventional turbocharged engines are configured to reduce the displacement acting on the turbine due to the difference in intake pressure between the upstream and downstream passages of the compressor of the supercharger. As a result, the turbine could not be operated sufficiently at low rotation speeds or low loads, and the reduction ratio could not be increased sufficiently. Therefore, in such a case, there is a problem that sufficient engine output and improvement in fuel efficiency cannot be obtained.

This invention was made by focusing on such conventional problems, and includes an intake bypass passage that communicates the combustion chamber of the engine with the intake passage, an intake control valve that opens and closes the intake bypass passage, and a supercharging system. an exhaust bypass passage that communicates a turbine upstream passage with a turbine downstream passage of the engine; and an exhaust control valve that opens and closes the exhaust bypass passage; The purpose of this invention is to solve the above problems by operating the system.

Hereinafter, this invention will be explained based on the drawings.

1 and 2 are diagrams showing an embodiment of the present invention.

First, to explain the structure, in FIG. 1, (1) is a cylinder block of an engine (2), and a piston (3) is slidably housed in the cylinder block (1). A cylinder head (4) is fixed to the upper end of the cylinder block (1), and these cylinder block (1), piston (3) and cylinder head (4)
defines a combustion chamber (5). Cylinder head (4)
An intake passage (7) that communicates with the combustion chamber (5) and the intake manifold (6), and an exhaust passage (8) that communicates with the exhaust manifold are formed. The exhaust passage (8) is opened and closed by an intake valve and an exhaust valve. The intake valve operates in conjunction with the rocking of the rocker arm (9), and the rocker arm (9) is rocked by the rotation of the cam Ql.

A cylinder cover αB is attached to the upper end of the cylinder head (4) so as to cover the rocker arm (9) and the cam (II). The spark plug 02 is installed, and the combustion chamber (5) and cylinder head (4)
A hole (131) communicating with the outside is formed.

A guide tube α is fixed in the hole (131), and a seat surface (151) is provided at one end of the guide tube Q41 on the combustion chamber (5) side.
However, a spring seat 061 is formed at the other end.

Guide tube (for 14+, from seat surface a9 to guide tube 04)
A large diameter communication hole (171 is formed, communication hole 0?) across the middle portion is communicated with the connection path 09 through the through hole Q81. The joint passage 09 communicates with the intake passage (7), and these communication holes (171, through hole 081 and joint passage 0
Reference numeral 9 constitutes an intake bypass passage (2) that communicates the combustion chamber (5) and the intake passage (8). A valve (211) is slidably inserted into the guide tube α.
1 has a pulp head @ that seats on the seat surface (151) and closes the intake bypass passage (2) at its tip. Also, a spring retainer (231 is fixed to the stem end of the valve (211). , spring retainer (
A valve spring C241 is compressed between the spring 231 and the spring H61. Valve Qυ is caused by this pulp spring so that the valve head @ seat surface 05
These valves (
211 and a pulp spring (241 constitutes an intake control valve that opens and closes the intake bypass passage (2). The valve (
An electromagnetic actuator (support) is fixed to the cylinder head (4) via a holder (5) at a position facing the stem end of the electromagnetic actuator 126.
1 is constructed as shown in FIG. In Fig. 2, (28) is the case of the electric/magnetic actuator (C) fixed to the cylinder head (4) via a holder. A protruding plunger 4 is slidably inserted into the holder.

The plunger (c) is located on an extension of the axis of the valve (211), one end of which faces the stem end of the valve (211), and a spring retainer formed at the other end.This spring retainer and the case ( A spring ■ is compressed between the two marks, and the spring biases the plunger (c) in the direction in which it separates from the valve (211).In addition, the plunger (c) is placed in the case (to). A solenoid 011 is housed so as to surround the valve (c), and when the solenoid (311 is energized), it moves the plunger @ in the direction of the valve (211.Solenoid 6
u is connected to the control circuit (32), and the control circuit C32
1 is incorporated in the control unit (331) shown in FIG.
(341 is a turbo supercharger,
is a turbine driven by engine exhaust; yc351
, a turbine (351) and a compressor (3
6) It has the following. Exhaust air flows from the turbine upstream passage (371) to the turbine (351) via the exhaust passage (8).
and is discharged from the turbine downstream passage (2) through an exhaust pipe (not shown). Fresh air is air cleaner (3
9 and an air flow meter (401) into the compressor upstream passage (from 411 to the compressor Zheng),
Fresh air is supplied from the compressor downstream passage (421) to the combustion chamber (5) via the throttle valve (43) and the intake passage (7). When fresh air is supplied to the combustion chamber (5), the fuel injection nozzle (4i) Fuel is injected into the fresh air (the intake air)
(The intake path (7) located downstream west of the throttle valve (431) and the fuel injection nozzle (4i)
) is open. The turbine upstream passage (37I) and the turbine downstream passage (9) are an exhaust bypass passage (44).
The exhaust bypass passage (44) is opened and closed by a swing pulp (451) which is an exhaust control valve.

The swing valve (451) is actuated by the swing valve controller (46). That is, the swing valve (45) is operated by the rod (471) via the fulcrum (481).
is connected to the diaphragm (49) of the controller (46), and the diaphragm is biased by a spring in the direction of closing the swing valve (451).
The downstream passage of the compressor (421) receives a force in the direction of opening the swing pulp (451) due to the pressure of the pressure chamber (521) led through the conduit all. Therefore, the swing valve (c) Downstream passage (pressure of 421 is a predetermined value (Vs), that is, spring 60)
When the biasing force is exceeded, the exhaust bypass path (, +4) is activated
open. That is, the exhaust bypass path (441) is opened and closed depending on the operating state, particularly the load.

On the other hand, the ignition coil (54) for the control unit) (331 Nistarter switch e > 31. Air flow meter (41 m), engine speed sensor 1.
Signals from the crank angle sensor e551 and a cooling water temperature sensor (not shown) are input, and the controller 1. The roll unit (g) uses these signals to control optimal ignition timing, optimal fuel injection timing and injection period, and optimal operation timing and time of the intake control valve (25). Here, the control circuit 62 that controls the operation of the intake control valve (251) will be explained. The control circuit (32 is represented as in the block diagram shown in FIG. This is an input circuit into which signals from a switch (53), an air 70 meter (40, ignition coil 54), a crank angle sensor mark, a cooling water temperature sensor, etc. are input.

The starter switch (531) detects the start position of the ignition key and outputs an ON signal when the ignition key is at the start position.

Air flow meter (4) outputs a signal proportional to the intake air flow rate, and ignition coil e541 outputs a signal proportional to the number of revolutions per unit time of the engine. Detects 180° signal and 720° signal, and with these signals,
It outputs a signal that indicates the position of the piston, and a cylinder discrimination signal that determines which of the plurality of cylinders the signal belongs to. In addition, the cooling water temperature sensor outputs a signal proportional to the cooling water temperature, and the input circuit (!56) digitally converts the signals from these sensors, shapes the waveform, and outputs it to the discrimination circuit 1571. ing. The determination circuit 57) determines whether the cooling water temperature signal from the input circuit 5 exceeds a reference value, and determines whether the signal from the starter switch 6;3) is an ON signal. Then, only when the cooling water temperature signal exceeds the reference value, a signal proportional to the magnitude thereof is output, and when the signal from the starter switch 53) is an ON signal, an own signal is output to the arithmetic circuit section. Furthermore, the intake air amount signal and engine rotational speed signal from the input circuit (g) are output as they are to the arithmetic circuit. The calculation circuit 61O calculates the opening time of the intake control valve (c) based on the signal from the discrimination circuit 1571 and the data previously input to R0M5I, and outputs it to RAM-.

That is, when the arithmetic circuit side receives the signal [l] indicating the ON signal of the starter switch (531) from the discrimination circuit 57), it outputs the valve opening time (T, ) previously input to the ROM 51 to the RAM l0). When the cooling water temperature signal is input from the discrimination circuit 5D, its magnitude and R are determined in advance.
OM5! The valve opening time (T2) is calculated from the data stored in J and output to RAM-.

Furthermore, if the cooling water temperature signal is not input from the discrimination circuit port, and only the intake air amount signal and engine speed signal, which are indexes of the engine load, are input, the magnitude of these signals and the ROM (51 Calculates the valve opening time (T,) as a map from the data stored in and outputs it to RAM II.
At this time, when a cooling water temperature signal is also input from the discrimination circuit 6η, the valve opening time (T4) is calculated as a map from these three factors and the data in the ROM 61, and the R-A M IO
Output to. This RAM II) is connected to a counter 6υ, and a cylinder discrimination signal and a piston position signal, which are signals from a crank angle sensor ω, are further input from an input circuit (G) to the counter 6υ.

The counter outputs a valve opening command signal to the output circuit I7J at a predetermined valve opening timing, for example, at the bottom dead center of the piston, based on each signal from the input circuit (G), and also outputs a valve opening command signal to the output circuit I7J at the valve opening time ( 1) Count. At this time, the valve opening time σ) counted is the valve opening time at the start (T
, ) is input, this valve opening time (T, ) dominates to exclude other valve opening times, and the counter 6υ is set to the valve opening time (T, ).
1) Count.

After counting this valve opening time cT), the counter D stops outputting the valve opening command signal to the output circuit [21]. The output circuit 1B energizes the solenoid C311 of the electromagnetic actuator ■ only during the time when the valve opening command signal is input from the counter 6υ, and when the solenoid (31+) is energized, the plunger (c) pushes the stem end of the pulp Qυ and sucks air. Bypass path ■ opens.Discrimination circuit 6 mentioned above?
), the arithmetic circuit, the ROM (59, RAM II), the counter and the output circuit as a whole are connected to the control circuit C12.
1, and the electromagnetic actuator (3) and the control circuit c321 constitute a control means 131 that operates the intake control valve (c) according to the operating state.

Next, the action will be explained.

First, when starting the engine, the ignition key is turned to the start position, and at this time, the control means 11 operates the intake control valve (c) for the valve opening time (T,). That is, an ON signal is input from the starter switch 531 to the control circuit C32, and the control circuit (33' changes the valve opening time (T) from a predetermined valve opening timing (for example, BDC') as described above.
, ) is energized to the solenoid CtU. Solenoid 01
When power is applied to 1, the plunger (c) will release the pulp (21+
The stem end roller of the pulp CD is pushed by the suction in the direction, and the pulp head (22+) is separated from the sheet surface α9 to open the intake bypass path (2).

At this time, the piston (3) is at the bottom dead center and the combustion chamber (5
) is filled with air-fuel mixture. The intake bypass path ■ is
As shown in Fig. 3, the air-fuel mixture in the combustion chamber (5) is opened for T1 hours from the bottom dead center, and the air-fuel mixture in the combustion chamber (5) flows from the intake bypass path (4) to the intake path (7) as the piston (3) rises. After that, when the power to the solenoid C111 is cut off, the plunger (c) is urged by the spring arm and moves away from the stem end of the pulp (211), and in response, the pulp 12D is released from the pulp spring c! , and closes the intake bypass passage (2).In this way, the intake air in the combustion chamber (5) is recirculated to the intake passage (7), thereby reducing the substantial compression ratio. Therefore, when starting the engine, the starting load can be reduced, battery consumption is improved, and starting performance is improved.On the other hand, at this time, the exhaust bypass path (■) does not open. This is because the discharge pressure of the compressor ■ is low and the control (4G) does not operate.Furthermore, the control unit (c) calculates the optimal fuel injection amount and ignition timing at the time of startup, and controls the fuel injection nozzle (d) and spark plug (121). As a result, engine startability is improved and battery consumption is further improved.

Next, when the engine is started and operating at low load,
The intake bypass path (■) and the exhaust bypass path (44J) are closed, and the performance of the turbocharger C341 is fully exhibited.In other words, during low load operation, the control circuit C32
The valve opening time (T, ) calculated by the arithmetic circuit r5 mark becomes zero, and the control means (63) does not operate the intake control valve Q51. In addition, the discharge pressure of the compressor (support) is not high enough to activate the controller (46), and the swing pulp (4) exhaust control valves are not activated. Therefore, the engine has a high compression ratio, combustion output, and improved fuel efficiency. At the same time, all of the increased exhaust gas due to the high compression ratio is transferred to the turbine C.
35+, it promotes supercharging of the compressor (3), obtains even higher output, and improves fuel efficiency. In addition, even in this case, when the signal from the cooling water temperature sensor exceeds the reference value, as described above, the control means 13
1 operates the intake control valve (251) for the valve opening time (T2) to open the intake bypass path (2).

1. Therefore, the engine has a low FE compression ratio, and knocking and engine burnout can be prevented.

Also, during high load operation, the pressure in the compressor downstream passage (421) is at a predetermined value (Vs), for example 4001
1Hg, or less, and cases where it exceeds a predetermined value (Vs). First, when the temperature is below a predetermined value (Vs), the intake bypass path (2) is opened for the valve opening time (T3) or the valve opening time (T4), and the exhaust bypass path (441 is closed. In other words, the cooling water temperature sensor When the signal from the discrimination circuit mark does not exceed the reference value, the cooling water temperature signal from the discrimination circuit mark is not input to the arithmetic circuit 6 bar, and the valve opening time (T'
) are determined only by the engine's intake air amount signal and engine speed signal. Therefore, the arithmetic circuit (to) these two
The control means 13) calculates the valve opening time (T3) from two factors as described above, and controls the valve opening time (T3) from the predetermined valve opening timing.
) only operate the intake control valve (c) to open the intake bypass path■
open. Further, when the signal from the cooling water temperature sensor exceeds the reference value, a cooling water temperature signal proportional to the cooling water temperature is input from the discrimination circuit 67) to the calculation circuit 6Q, and the factor determining the valve opening time is the cooling water temperature signal. , an intake air amount signal, and a rotational speed signal. Therefore, the calculation circuit 58 calculates the valve opening time (T4) from these three factors as described above, and the control means calculates the valve opening time (T4) from the predetermined valve opening timing.
Activate the intake control valve (c) only to open the intake bypass passage ■. Therefore, under high load, the effective compression ratio of the engine is reduced, making it possible to prevent knocking and engine burnout, and to reduce the displacement acting on the turbine (c). However, since the exhaust bypass passage (441) is closed and the engine is operated under high load, the turbine supercharger (commercial) is able to sufficiently supercharge and obtain an appropriate supercharging pressure. It is possible to increase output and improve fuel efficiency.Next, the pressure in the compressor downstream passage (421) reaches a predetermined value (
When the value exceeds the predetermined value (Vs), the intake bypass path (2) is opened in the same way as when the value is less than the predetermined value (Vs), and the exhaust bypass path (4) is also opened.

That is, when the pressure in the compressor lower fL side passage (421) exceeds a predetermined value (Vs), the pressure in the pressure chamber (521) of the controller (461) overcomes the biasing force of the spring, and the diaphragm (491) moves in the direction of the spring (A). As the diaphragm (491) moves, the rod (471) moves and the swing valve (451 opens, opening the exhaust bypass path (
441 opens. Therefore, most of the exhaust gas that has flowed from the combustion chamber (5) to the turbine upstream passage r371 flows through the exhaust bypass passage (441) to the turbine downstream passage (■), and the amount of exhaust gas acting on the six turbines is significantly reduced. do.

Therefore, supercharging pressure is reduced. In addition, at this time, as mentioned above, the intake bypass passage ■ is open for the valve opening time (T, ) or the valve opening time (T4), so the compression ratio is reduced, and a large part of this reduced displacement is A portion flows through the exhaust bypass passage (441) to the turbine downstream passage (toward).As a result, the compression ratio is reduced and the boost pressure is reduced, making it possible to prevent engine burnout and knocking. .

Figure 4 shows these effects in terms of the relationship between engine speed and load. Area (B) indicates a medium load area, where the intake-bypass path (201 is open and the exhaust bypass path (441 is closed).Area C) represents a high-load area, where the intake bypass path (201) is open and the exhaust bypass path (441 is closed). (44J are both opened, for example, the compression ratio is 8.0, and the supercharging pressure is controlled to 40011MHH.'
ing.

In addition, in the above embodiment, the load sensor is simplified,
In order to reduce production costs, the exhaust bypass valve is controlled by a swing controller operated by the pressure in the downstream passage of the compressor, but the present invention is not limited to this. That is, the above pressure may be detected by a pressure sensor, and the exhaust bypass path may be electrically opened when the pressure is higher than a predetermined pressure, or a signal of intake air amount or intake air amount/engine speed may be used instead of the pressure sensor. Good too. Further, although the load, which is one of the factors for opening and closing the intake bypass passage, has been detected based on the intake air amount and rotational speed of the engine, the present invention is not limited to this. For example, the load can be determined based on the throttle opening degree, intake passage negative pressure, torque, or the like. When torque is used, for example, the ratio in Figure 5 may be increased, and the compression ratio may be reduced during high loads with large torque.

As described above, according to the present invention, there is provided an intake bypass passage that communicates the combustion chamber of the engine with the intake passage, an intake control valve that opens and closes the intake bypass passage, a turbine upstream passage of the supercharger, and a turbine upstream passage of the turbocharger. A turbo supercharger comprising an exhaust bypass passage that communicates with a downstream passage, and an exhaust control valve that opens and closes the exhaust bypass passage, the intake control valve and the exhaust control valve being operated according to operating conditions, respectively. Since it is a compression ratio control device for an engine equipped with an engine, the boost pressure and compression ratio can be appropriately set depending on the operating condition. therefore,
It is possible to reduce fuel consumption, obtain high output, and prevent engine burnout and knocking.

In the above embodiment, the intake bypass passage is formed in the cylinder head, the intake bypass passage is communicated with the intake passage on the downstream side of the throttle valve, and the intake control valve is also provided in the cylinder head, so that the intake air is removed from the combustion chamber. It is possible to prevent the throttle valve and parts in the vicinity of the throttle valve from deteriorating due to the air-fuel mixture that is returned to the air passage, and it is possible to simplify the structure of the intake control valve. Furthermore, since the exhaust control valve is controlled by a swing controller operated by the pressure in the downstream passage of the compressor, the load sensor can be simplified and production costs can be reduced.

[Brief explanation of the drawing]

Figures 1 and 2 are diagrams showing an embodiment of the compression ratio control device for a turbocharged engine according to the present invention. FIG. 3.4 is an enlarged view of the control means, and is an explanatory diagram of the operation of the compression ratio control device for a turbocharged engine according to the present invention. FIG. Fig. 4 shows the relationship between engine speed and load, and Fig. 5 shows the compression ratio control system for a turbocharged engine according to the present invention. FIG. 3 is a diagram showing the relationship between compression ratio and torque when engine load, which is one of the control factors, is expressed in torque. (2)...Engine (5)...Combustion chamber (7)
...Intake path ■...Intake binocular path (25
)...Intake control valve (Foundation)...Turbo supercharger (3
'ri...Turbine upstream passage■...Turbine downstream passage (4)...Exhaust bypass passage (45)...Swing valve (exhaust control valve) Patent applicant Nissan Motor Co., Ltd. Agent Patent attorney I have an army - Department Figure 3, Figure 4, Figure 5.

Claims (1)

[Claims] An intake bypass passage that communicates the combustion chamber of the engine with the intake passage; an intake control valve that opens and closes the intake bypass passage; an exhaust bypass passage that communicates the turbine upstream passage and the turbine downstream passage of the supercharger; An exhaust control valve for opening and closing a bypass passage, and a compression ratio control device for a turbocharged engine, wherein the intake control valve and the exhaust control valve are each operated according to operating conditions. A compression ratio control device for an engine equipped with a turbocharger.