JPH01315A - supercharged engine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is configured such that the geometric compression ratio of the engine, that is, the ratio of the internal cylinder volume at top dead center to the volume at bottom dead center, is large. The present invention also relates to a supercharged engine equipped with a communication passage that communicates the exhaust passages of each cylinder.

(Prior Art) Engines equipped with a supercharger to increase the amount of intake air filling and thereby obtain high output have been known.
For example, Japanese Utility Model Application No. 56-171630 discloses an example of such a supercharged engine.

However, if the supercharging pressure becomes too high, the combustion chamber temperature will rise unduly, causing abnormal combustion such as knocking, which will have an adverse effect on output performance. For this reason, in the past, it was not possible to set a high geometric compression ratio, and therefore, at low loads when the supercharging effect was low, the thermal efficiency of the engine was poor and it was not always possible to obtain satisfactory fuel efficiency.

Furthermore, in order to suppress the occurrence of knocking as described above, a method is also known in which the air-fuel mixture is made richer than the required air-fuel ratio in terms of output, and the combustion chamber temperature is lowered by the latent heat of vaporization of the fuel. However, in this method, fuel that does not contribute to engine output is supplied, resulting in a problem that fuel efficiency deteriorates.

For this reason, set the geometric compression ratio to a relatively high value of 8.5 or higher, and set the intake valve closing timing at least 50 degrees later than bottom dead center to prevent the effective compression ratio from becoming unduly large. It has been proposed to configure the engine so as to suppress the occurrence of knocking and improve fuel efficiency in the non-supercharging range.

In addition, in a supercharged engine, increasing the boost pressure causes the exhaust gas temperature to rise, causing the turbocharger's turbine to
There is also the problem of thermal deterioration of the exhaust system, such as the air-fuel ratio sensor or the catalyst.

In view of this, a communication passage is provided to connect the exhaust passages of each cylinder in the operating range where the exhaust gas temperature is high, thereby preventing the exhaust gas pressure from becoming unreasonably high. A supercharged engine that suppresses temperature has been proposed.

(Problem to be solved) However, when combining the configurations proposed above based on each requirement, for example, when the intake valve closing timing is set at least 5Q degrees later than the bottom dead center, such as during low load, Furthermore, when accelerating from a situation where the communication passage is closed, the amount of filling into the engine does not increase immediately due to the above-mentioned late closing control, and as a result, there is a problem that desired engine output cannot be obtained.

Furthermore, if the exhaust passage is communicated during acceleration, the volume of the passage from the combustion chamber 6 to the turbine will rapidly increase, causing a problem in that the exhaust gas energy will temporarily decrease and the acceleration response will deteriorate.

(Means for Solving the Problems) The present invention has been constructed in view of the above circumstances, and is capable of effectively suppressing the occurrence of knocking and achieving desired results in a supercharged engine with a high geometric compression ratio. The purpose of this project is to provide an engine that can obtain high output, especially acceleration performance.

Furthermore, it is an object of the present invention to provide a supercharged engine that can achieve better results in terms of fuel efficiency than conventional supercharged engines.

The configuration of the present invention is such that the geometric compression ratio of the engine is 8.5 or more, and the intake valve is closed at the maximum amount of retardation depending on the engine operating condition, and the crank angle is at least 50 degrees below bottom dead center. In a supercharged engine, the supercharged engine is provided with a late closing control means for controlling the closing timing so as to close later than 100 degrees, a communication passage communicating the exhaust manifolds of each cylinder, and a control valve for opening and closing the communication passage. The control valve is configured to open the control valve after canceling the slow closing control when acceleration is performed from a state where the closing control is being performed and the control valve is closed. It is characterized by

(Function) According to the present invention, the geometric compression ratio of the engine, that is, the ratio of the cylinder volume when the piston is at the bottom dead center to the cylinder volume when the piston is at the top dead center, is the same as that of a normal engine. It is set higher than the configuration.

Further, the closing timing of the intake valve can be changed. In particular, the intake valve's closing timing is controlled at a crank angle later than the bottom dead center, and its maximum late closing amount is at least 50 degrees or more after the bottom dead center in terms of crank angle. be.

In this case, the closing timing of the intake valve is set to a late closing amount in accordance with the operating state so as to prevent knocking and to obtain as high a charging efficiency as possible.

Further, the communication passage of the exhaust passage is opened during a predetermined operation in order to suppress an unreasonable increase in exhaust gas temperature or exhaust gas pressure.

In the present invention, when an acceleration operation is performed in an operating state where the intake valve is controlled to close slowly and the control valve is closed to the communication passage, the slow-close control is immediately stopped. . However, in this case, the control valve does not open immediately;
It is then controlled to open at an appropriate time.

The operating state is basically determined by the engine speed and the engine load, and the engine load can be detected by, for example, detecting the intake pipe pressure, the throttle valve opening, and the like.

(Effects of the Invention) According to the present invention, when an acceleration operation is performed, the slow closing control of the intake valve is immediately canceled, so that blowback of intake air can be suppressed. A desired output can be ensured. In other words, acceleration response can be improved. In this case, when the exhaust passage is not in communication, the control valve is maintained in the closed state for a predetermined period of time even if the operating state reaches a region where communication is required. As a result, exhaust gas energy can be introduced into the turbine without decreasing it, and high output can be maintained.

Note that this control is performed only during acceleration and is not performed continuously, so problems such as knocking and thermal deterioration of the exhaust system do not occur.

Furthermore, according to the present invention, in suppressing an unreasonable rise in exhaust gas temperature, it does not depend on the heat of vaporization of the fuel, and since the geometric compression ratio is set large, energy efficiency is good. can be improved.

(Description of Examples) Examples of the present invention will be described below with reference to the drawings.

Referring to FIG. 1, the engine to which the present invention is applied is
It is a 4-cylinder engine, and each cylinder 2 of engine 1 in this example
A piston (not shown) is reciprocatably housed inside each of a, 2b, 2C1, and 2d, and the space above the piston constitutes a combustion chamber 3. An intake passage 4 and an exhaust passage 5 communicate with this combustion chamber 3.

The intake passage 4 branches near the combustion chamber 3, and has a primary port (5a) for low loads and a secondary port (5a) for high loads.
b opens into the combustion chamber 3. Also, in engine 1 in this example, there are also two boats on the exhaust side. a, 7b, with an intake valve and an exhaust valve associated with the respective port of each passage 4.5.

An air cleaner 8 and an air 70-sensor 9 are installed upstream of the intake passage 4, and a compressor 11 of a turbo supercharger 10 is installed downstream thereof.

An intercooler 12 is downstream of this compressor 11.
and throttle valve 13 are arranged in this order. A surge tank 14 is provided downstream of the throttle valve 13.

In the vicinity of the downstream combustion chamber 3, an injector 15 is attached near a branch point of a primary branch intake passage and a secondary branch intake passage through which fuel is injected, forming an intake system.

This injector 15 has a structure including two injection ports along the respective passage directions so that fuel can be injected and supplied to each of the secondary and secondary intake passages.

Further, an on-off valve 4a that opens in a high load region is provided in the intake passage on the secondary side.

Furthermore, the air cleaner 8 has an intake temperature sensor 8a that measures the intake air temperature, the throttle valve 13 has a throttle sensor 13a that detects the opening of the valve, and the surge tank 14 has an intake pipe pressure sensor 13a that measures the intake pipe pressure. A pressure sensor 14a for detection is attached to each.

Further, in the exhaust passage 5, a turbine 16 is arranged on a common axis with the compressor 11. In the structure of this example, the exhaust manifold is divided into two parts, each of which communicates with the turbine 16 independently. Further, a bypass passage 17 is formed in the exhaust passage 5 to bypass the turbine 16 and guide the exhaust gas to the downstream side. A wastegate valve 18 is arranged in this bypass passage 17.

This wastegate valve 18 has a diaphragm device 18a.
The pressure inside the intake pipe downstream of the compressor 11 is introduced into the rediaphragm device 18a through the pressure introduction pipe 18b.

As a result, when the intake pressure downstream of the compressor 11, that is, the supercharging pressure, exceeds a predetermined value, the wastegate valve 18 opens, bypassing the turbine 16, and part of the exhaust gas is sent to the downstream side.

The engine 1 of this example includes communication passages 19 and 20 that communicate the exhaust passages 5 of each cylinder.

In this case, the communication passage 19 is connected to the first cylinder 2a and the fourth cylinder 2a.
d, and the communication passage 20 connects the second cylinder 2b and the third cylinder 2.
They communicate with C.

These communication passages 19 and 20 are provided with communication control valves 21 that open and close the passages.

The engine 1 of this example includes an on-off valve 4a that opens and closes a secondary intake passage communicating with the secondary boat 6b, and the communication passage 19.
A control system for controlling a communication control valve 21 that opens and closes 20 is provided.

This control system includes a diaphragm device 22 that controls the opening and closing of the on-off valve 4a, and a diaphragm device 23 that controls the opening and closing of the communication control valve 21.

A diaphragm device 22 for controlling the on-off valve 4a is connected to a vacuum tank 25 via a conduit 24a via a three-way solenoid valve 24, and a diaphragm device 23 for controlling the communication control valve 21 is connected to a conduit 26 via a three-way solenoid valve 26.
It is connected to the vacuum tank 25 by H.

Vacuum tank 25 is connected to conduit 25 via check valve 27.
It is connected to the surge tank 14 by a.

Under normal conditions, the three-way solenoid valve 24 is connected to the diaphragm device 2.
One of the chambers of 2 is communicated with the atmosphere, and in this case, the on-off valve 4a is open.

When the three-way solenoid valve 24 is actuated to communicate the chamber with the vacuum tank 25, the negative pressure held within the vacuum tank is introduced through the conduit 24a, and the on-off valve 4a is closed.

Referring to FIG. 2, the valve timing of the intake and exhaust valves used in this engine 1 is shown, and the closing timing of the secondary side intake valve is set to be later than that of the negative side intake valve. ing.

Therefore, when the on-off valve 4a is closed, the valve timing of the secondary intake valve does not affect the intake air intake, so the closing timing of the intake boat as a whole becomes relatively fast, and the on-off valve 4a closes. In this case, the secondary port (6b) is closed late, and the overall closing timing of the intake boat is delayed. That is, in this case, late closing control of the intake valve is achieved.

On the other hand, the diaphragm device 23 for the communication control valve 21
When one chamber communicates with the vacuum tank 25 due to the operation of the three-way solenoid valve 26, the communication control valve 2
1 opens.

Further, the vacuum tank 25 is connected to the surge tank 14 via a conduit 28, and if the opening degree of the throttle valve 13 is small and the negative pressure inside the surge tank 14 becomes strong,
The check valve 27 opens and negative pressure is introduced into the vacuum tank 25. Then, when the opening degree of the throttle valve 13 increases and the negative pressure becomes weaker than the vacuum tank 25, the check valve 27 closes. As a result, the vacuum tank 2
The negative pressure introduced into the vacuum tank 25 is maintained within the vacuum tank 25.

The engine 1 also includes an electronic control unit 28 which preferably includes a micro-combination unit that outputs command signals for controlling the fuel injection amount to the injector 15, the on-off valve 4a, the communication control valve 21, etc. is provided.

The control unit 28 includes a signal from the air flow sensor 9 indicating the amount of intake air, a signal from the throttle sensor 13a indicating the opening degree of the throttle valve 13, and an intake air temperature sensor 8.
a'-Pressure sensor 14aR A signal representing the engine rotation speed, etc. is input.

The control unit 28 calculates the human input signal and outputs a control signal to the three-way solenoid valves 24 and 26.

It also outputs a predetermined fuel injection control signal to the injector 15.

Regarding the supercharged engine configured as above, the opening/closing control of the opening/closing valve 4a and the communication control valve 21 will be explained.

Referring to FIG. 3, a flowchart for controlling the on-off valve 4a is shown.

In FIG. 3, the control unit 28 first initializes the system and reads various data (Sl). This data includes the engine speed Ne, the intake pipe internal pressure Pb1 based on the signal from the pressure sensor 14a, and the throttle valve opening TA.

Next, it is determined whether the engine is in an idle state (S2
).

When the engine 1 is in an idle state, the control unit 28 outputs a closing signal for the on-off valve 4a to the three-way solenoid valve 24 (S3).

Therefore, in this case, the secondary port 6b does not function and intake air is introduced only from the negative port, so that late closing control is not performed as a result.

This operation is necessary because the combustion state is unstable in extremely low speed and low load operating conditions such as idling, and if the intake valve 6 is controlled to close late in such conditions, combustion will be affected by blowback of intake air. This was done in consideration of the fact that it would encourage instability.

If the engine is not in an idling state, the control unit 28 determines whether the engine is in an accelerating state based on the magnitude of the rate of change ΔTA of the throttle valve opening TA (S4).
.

In this case, if the rate of change ΔTA exceeds the predetermined value TAo, it is determined that the vehicle is in an accelerated state.

If the acceleration state is determined, the control unit 2
8, the first shift of the intake pipe internal pressure pb is set to a predetermined value Pbo.
(For example, -10QmmHg) or more is determined (S5). In this determination, if the intake pipe internal pressure pbO value is less than or equal to the predetermined value Pbo, a close signal is output to the on-off valve 4a (S6).

That is, the late closing control of the intake valve is not substantially performed.

This is because, in the case of acceleration in this region, a higher filling rate can be obtained by not causing blowback.

Further, when the intake pipe internal pressure PbO value is equal to or higher than the predetermined value Pb0, an open signal is output to the on-off valve 4a (S7).

This is because, in this region, the pressure in the combustion chamber becomes high and there is a risk of non-king, so it is necessary to generate blowback to limit the increase in the filling rate.

Furthermore, even when it is determined in step (S4) that the engine is in a non-accelerating state, it is similarly determined whether the value of the intake pipe internal pressure Pb is equal to or greater than a predetermined value Pbo (S8).

If it is below the predetermined value Pbo, unlike the acceleration state, an open signal is output to the on-off valve 4a. This is to increase the opening degree of the throttle valve 13 by causing blowback, thereby reducing pumping loss.

Further, the control unit 28 of this example is provided with a map that gives the opening degree of the on-off valve 4a according to the engine speed Ne and the intake pipe internal pressure pb, and when the intake pipe internal pressure Pb is larger than a predetermined value Pb0, , engine speed Ne
Based on the intake pipe internal pressure Pb, the opening signal obtained from the map is output to the on-off valve 4a (S9).

Therefore, as shown in FIG. 4, in a non-accelerated state, that is, in a steady operating state, the on-off valve 4a is closed in the shaded region of the figure.

Next, the control of the communication control valve 21 will be explained with reference to FIG.

In FIG. 5, the control unit 28 first initializes the system and reads various data (SIO). This data includes engine speed Ne,
The intake pipe internal pressure pb is determined by the signal from the pressure sensor 14a.
The pressure applied to the turbine 16, that is, the exhaust pressure Pex and the throttle valve opening TA are included.

Next, the control unit 28 controls the throttle valve opening T
It is determined whether the engine is in an accelerating state from the magnitude of the rate of change ΔTA of A (Sll).

If the rate of change ΔTA exceeds the predetermined value TAG, it is determined that the vehicle is in an accelerated state.

If the acceleration state is determined, the control unit 2
Step 8 sets a timer and starts a counter (S12).

Then, the exhaust pressure P,ex becomes a predetermined value Pb (for example, +450 m
It is determined whether the amount exceeds ml (g) (S13). If the exhaust pressure Pex is below the predetermined value Pb+, the control unit 28 outputs a close signal for the communication control valve 21 to the three-way solenoid valve 26 (S14). In addition, if the exhaust pressure Pex exceeds the predetermined value Pb, the timer is reset/reset after the timer set time has elapsed.
A signal to open the communication control valve 21 is sent to the three-way solenoid valve 26.
(S15, S16, S1?).

During acceleration, the demand for output is strong, so even if the exhaust pressure Pex
Even if Pb exceeds a predetermined value Pb, the operation to open the communication control valve 21 is temporarily delayed.

On the other hand, in the acceleration determination (3, 11), even if it is determined that the vehicle is in a non-acceleration state, the control unit 28
Similarly, it is determined whether the exhaust pressure Pex exceeds a predetermined value Pb1 (318). In this case, if the predetermined value Pb1 is exceeded, the control unit 28 immediately outputs a signal to open the communication control valve 21 to reduce the load on the turbine 16. .

Further, when the exhaust pressure Pex is less than or equal to the predetermined value Fly, the control unit 28 determines whether the engine rotation speed Ne is less than or equal to the predetermined value Ne+ (for example, 3500 rpm) (S19). If it does not exceed the predetermined value Ne1, a close signal for the communication control valve 21 is output, but if the rotation speed Ne is larger than the predetermined value Ne1, an open signal for the communication control valve 21 is output (S17). Exhaust pressure Pe
x can be lowered. In a non-accelerating state, the demand for output is not strong, so by lowering the exhaust pressure Pex as much as possible,
Thermal deterioration of the exhaust system such as the turbine 16 can be prevented.

On the other hand, if the rotational speed does not exceed the predetermined value Ne1, a closing signal for the communication control valve 21 is output (S20).

The relationship between the control of the on-off valve 4a and the communication control valve 21 during acceleration will be described with reference to FIG. 6.

When the control unit 28 determines that the acceleration state is present based on the opening change ΔTA of the throttle valve 13 at point T1 as shown in FIG. 6(d), the intake pipe internal pressure pb increases as shown in FIG. 6(C). Since it is less than the predetermined value Pbo,
As shown in FIGS. 6(a) and 6(b), both the on-off valve 4a and the communication control valve 21 are in a closed state.

In this case, the control unit 28 controls the sixth (b)
) Immediately close the on-off valve 4a as shown in the figure.

This prevents blowback and ensures high filling efficiency to meet output demands. Thereafter, if the intake pipe internal pressure Pb increases and exceeds a predetermined value Pbo, a knocking problem will occur, so the on-off valve 4a is closed as shown in FIG. 6(b). As a result, the secondary port) 6b functions and late closing control is achieved.

That is, it is possible to suppress the temperature rise in the combustion chamber 3 and prevent the occurrence of knocking.

On the other hand, as shown in FIG. 6 (83), the closed state is maintained until a predetermined time T2 when the exhaust pressure Pex exceeds the supercharging pressure after acceleration determination, or until T3 when the timer set time elapses.

Therefore, in an accelerated state, high-energy exhaust gas can be introduced into the turbine 16, and responsiveness during acceleration can be improved.

As described above, with the configuration of this example, desired output performance can be ensured while suppressing knocking.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a supercharged engine according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing the valve timing of intake and exhaust valves, and FIG. 3 is an illustration of the contents of the on-off valve control. FIG. 4 is a graph showing the relationship between the opening/closing of the on-off valve and the operating state; FIG. 5 is a flow chart showing the control contents of the communication control valve; as well as(
6) The figure is a graph showing the relationship between control of the communication control valve and the on-off valve during acceleration. 1...Engine, 2a% 2b, 2C, and 2d...Cylinder, 3.
...Combustion chamber, 4...Intake passage, 4a...
...Opening/closing valve, 5...Exhaust passage, 6a...
...-Next port, 6b...Secondary boat, 7a, 7b...Exhaust side port, 8...
Air cleaner, 9... Air flow sensor, 10
...Turbo supercharger, 11...
...Compressor, 12...Intertara,
13... Throttle valve, 14... Surge tank, 14a... Pressure sensor, 15...
... Injector, 16 ... Turbine, 17
...Bypass passage, 18...Wastegate valve, 18a...Diaphragm device, 18b...
...Pressure introduction pipe, 19.20...Communication path, 21
......Communication control valve, 22.23...Diaphragm device, 24.26
... Three-way solenoid valve, 27 ... Check valve, 28 ... Control unit. BDCTDCCBDC Engine rotation speed Figure 6 Procedure correction writing method) % formula % 1. Incident display 1988 Patent Application No. 155073
No. 2, Title of the invention Supercharged engine 3, Relationship to the case of the person making the amendment Applicant □ Name (313) Mazda Motor Corporation 4, Agent 5, Date of amendment order August 25, 1988 6, Subject of amendment Column 7 of brief explanation of drawings in the specification, contents of amendment

Claims (1)

[Claims] The geometric compression ratio of the engine is configured to be 8.5 or more, and the intake valve is configured to close at least 50 degrees later than bottom dead center at the crank angle as the maximum late closing amount depending on the engine operating condition. A state in which the late-closing control is performed, comprising: a late-closing control means for controlling the closing timing, a communication passage that communicates the exhaust manifolds of each cylinder, and a control valve that opens and closes the communication passage, and A supercharged engine characterized in that when acceleration is performed from a state where the control valve is closed, the control valve is opened after canceling the slow closing control of the intake valve. .