JPS6160981B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition timing control device for an engine equipped with a supercharger driven by exhaust gas, that is, an exhaust turbo supercharger.

In general, combustion in a spark ignition engine is as shown in Figure 1, where the air-fuel mixture is ignited at point B after a slight ignition delay period T from the spark ignition point A caused by the spark plug, and during the flame propagation period B-C. Then, after a direct combustion period of C-D, the maximum explosion pressure is reached at point D, and D
-The process leading to the afterburning period of
It is known that maximum engine output can be obtained when the angle is set at approximately 10 degrees.

In this case, the ignition delay period T is approximately inversely proportional to the charging efficiency, which is the ratio of the weight of the intake fresh air mixture to the weight of the mixture occupying the stroke volume under standard conditions, and the charging efficiency is proportional to the rotation speed. is inversely proportional to the load, and is directly proportional to the load. Therefore, the ignition delay period T becomes longer in proportion to the rotational speed, and is inversely proportional to the load. The relationship becomes shorter.

Therefore, in conventional ordinary engines (those without turbocharging), a centrifugal advance mechanism is installed in the distributor to control the rotation speed, and when the intake pipe negative pressure is set to atmospheric pressure, The characteristics of the ignition timing are controlled, for example, as shown by the solid line in Figure 2, while the distributor is equipped with a vacuum advance mechanism that uses the intake pipe negative pressure as an input signal to control the rotation speed. The characteristics of the ignition timing when constant is controlled as shown by the solid line in FIG. 3, for example.

On the other hand, an exhaust turbo supercharger has the feature that it can use the energy contained in the exhaust gas from the engine to improve the engine's output, but since it requires a considerable amount of exhaust gas energy to drive the exhaust turbine, In a turbocharged engine, the engine speed is low and the amount of exhaust gas from the engine is small.
In the low load range, turbocharging is not performed, resulting in a so-called non-turbo state, and in the rotation/load range above a certain level, turbocharging (on-turbo) is performed, and in the turbocharging (on-turbo) state, charging is The efficiency increases rapidly, and the ignition delay period T becomes shorter even more rapidly than when the load increases in a non-turbo state due to the sudden increase in charging efficiency. Applying the angle mechanism as is means that the point D of maximum explosion pressure in the turbocharged state is at or near top dead center, or in some cases, due to the shortening of the ignition delay period T due to supercharging. before top dead center (BTDC)
will be moved to.

This shift of the maximum explosion pressure point D toward top dead center causes an explosion during compression during the upward stroke of the piston, which not only causes a sudden drop in engine output, but also increases noise due to knocking. In some cases, this may lead to damage to the engine, and an engine that can withstand this damage will be significantly heavier.

Therefore, the maximum explosion pressure point D during turbocharging
In order to prevent the shift toward the top dead center, the second
The control characteristics of the ignition timing with respect to the rotation speed shown in the figure are as follows:
It may be possible to move parallel to the retard direction by the amount that shortens the ignition delay period T during turbocharging as shown by the two-dot chain line. However, in the low rotation/low load range where the engine is not yet fully operational, it is not possible to control the ignition timing to the optimum level, resulting in negative outcomes such as reduced output and increased fuel consumption. Become.

Furthermore, when controlling the ignition timing of a turbocharged engine using the conventional method described above, it is possible to prevent knocking during turbocharging by setting the compression ratio in the engine low. Lowering the compression ratio is not a good idea because it lowers the thermal efficiency and reduces engine output over the entire operating range.

The present invention provides a device that appropriately controls the ignition timing in such a turbocharged internal combustion engine over the entire operating range with a simple configuration.

For this reason, the present invention provides a turbocharged engine that includes an exhaust turbocharger in the intake system and supplies fuel in an amount corresponding to the amount of intake air to the engine from a fuel injection nozzle. The distributor with a centrifugal advance mechanism is provided with a pressure-type actuation mechanism that operates the breaker plate in the advance/retard direction, and the pressure-type actuation mechanism urges the breaker plate in the advance direction. A spring is provided in the pressure chamber of the pressure operating mechanism to control the fuel supply pressure to the fuel injection nozzle, and the breaker plate is operated in a retard direction against the spring at the fuel supply pressure. The configuration was introduced as follows.

In electronically controlled fuel injection engines, the amount of air taken into the internal combustion engine is directly measured using an air flow meter, etc., and a properly controlled amount of fuel is injected from the fuel injection nozzle accordingly. The fuel supply pressure to the injection nozzle is automatically controlled so that it is always a predetermined value (for example, about 2.5 kg/ ^cm2 ) higher than the pressure of intake air to the engine, that is, the intake pressure. In non-turbo mode, the pressure gradually approaches atmospheric pressure in proportion to the increase in load on the vacuum side, and in on-turbo mode, it gradually increases in proportion to the increase in load on the side above atmospheric pressure. Therefore, the fuel supply pressure to the fuel injection nozzle is
It is low when in non-turbo mode and high when on turbo mode.

Therefore, the breaker plate of the centrifugal advance mechanism distributor of the engine is provided with a pressure-type actuation mechanism that operates the breaker plate in the advance/retard direction, and the pressure-type actuation mechanism is used to advance the breaker plate. A spring is provided that biases in an angular direction, and the pressure chamber of the pressure-operated mechanism is provided with a fuel supply pressure to the fuel injection nozzle, and the breaker plate is applied in a retard direction against the spring at the fuel supply pressure. By introducing it to operate,
When non-turbo, the ignition timing in the engine can be advanced in proportion to the decrease in intake pressure due to the decrease in fuel supply pressure and the action of the spring, while when on-turbo, the ignition timing can be controlled to be retarded in proportion to the increase in intake pressure. .

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, 1 is an engine having an intake manifold 2 and an exhaust manifold 3, 4 is an exhaust turbo supercharger directly connected to an exhaust turbine 5 and a blower compressor 6, and 7 is an engine having an intake manifold 2 and an exhaust manifold 3. Various devices installed in the exhaust system, such as a muffler, a catalytic converter, or a reactor, which release exhaust gas into the atmosphere are shown. It is connected to the discharge side of the blower compressor 6 through a passage 9, and the suction side of the blower compressor 6 is connected to an air cleaner 11 through a suction passage 10, and an air flow is provided in the suction passage 10 to measure the amount of intake air. A meter 12 is provided, and the intake manifold 2 further includes:
Fuel pump 14 connected to fuel tank 13
A fuel injection nozzle 16 connected to the cylinder via a fuel supply passage 15 is provided for each cylinder.

The fuel injection nozzle 16 is connected to the computer 1
associated with said air flow meter 12 via 7;
Fuel is supplied from a fuel injection nozzle 16 in an amount corresponding to the actual amount of intake air measured by an air flow meter 12, and the intake manifold is connected to the fuel supply passage 15 via a passage 18. 2, the fuel supply passage 15
When the fuel supply pressure in the intake manifold 2 is higher than the intake pressure in the intake manifold 2 by a predetermined value (for example, about 2.5 kg/cm ² ), surplus fuel is released from the return passage 19 to the fuel tank 13. The fuel supply pressure at is always approximately lower than the intake pressure.
A pressure regulator 20 is provided which maintains a pressure higher by 2.5 Kg/cm ² .

Further, the exhaust side of the exhaust turbine 5 is an exhaust pipe 2.
1 to the muffler 7, and the inlet side of the exhaust turbine 5 is connected to the exhaust manifold 3 via an exhaust passage 22, respectively.

Reference numeral 23 denotes a centrifugal advance angle which has an advance angle characteristic as shown by the solid line in FIG. A distributor equipped with a mechanism 25, inside which the camshaft 2 is mounted.
A breaker plate 2 having a breaker arm 27 with a contact 26 that turns on and off by rotation at 4
8 is provided, and when the breaker plate 28 rotates in the direction of arrow 29, the ignition timing is advanced, and when it rotates in the direction of arrow 30, the ignition timing is retarded.

Reference numeral 31 indicates a pressure-type operating mechanism for rotating the breaker plate attached to the side surface of the distributor 23, and the pressure-type operating mechanism 31 is connected to the diaphragm case 32 and the breaker plate 28 by a rod 3.
3, and pressure chambers 35 and 36 formed on both sides of the diaphragm 34. One of the pressure chambers 35 communicates with the atmosphere, and the diaphragm 34 and the breaker plate 28 are connected inside the diaphragm 34, and pressure chambers 35 and 36 are formed on both sides of the diaphragm 34. A spring 37 is provided in the other diaphragm chamber 36 to bias the ignition timing in the direction of advance of the ignition timing as indicated by the arrow 29. It is introduced through a passage 38 so as to operate in the retardation direction of the arrow 30.

In this configuration, the ignition timing of the engine is controlled by the distributor 2 with respect to the engine speed.
The centrifugal advance mechanism 25 in FIG. 3 controls the advance direction in accordance with the characteristics shown by the solid line in FIG. 2 as the rotational speed increases.

On the other hand, in the region where the opening degree of the throttle 8 is small,
Since the amount of intake air is small, and therefore the amount of exhaust gas is small, and the rotation of the exhaust turbo supercharger 4 is slow, supercharging by the exhaust turbo supercharger 4 is not performed (non-turbo state), and in this region, the intake manifold 2 The intake pressure in the fuel supply passage 15 is low as it is close to the vacuum side, and therefore the fuel supply pressure in the related fuel supply passage 15 is also low.
Since a low pressure acts on the pressure chamber 36 of the pressure-type actuating mechanism 31, the ignition timing is advanced by rotating the breaker plate 28 connected to the diaphragm 34 in the advance direction of the arrow 29 using the spring 37. Ru. Next, as the throttle valve 8 is opened, the intake pressure gradually changes to approach atmospheric pressure, and the fuel supply pressure related to this intake pressure also gradually increases as the throttle valve 8 opens, that is, the engine load increases. As the breaker plate 28 connected to the diaphragm 34 in the pressure actuation mechanism 31 rotates in the retard direction of the arrow 30 against the spring 37, the ignition timing relative to the load gradually changes as the load increases. Delay controlled.

Then, when the throttle valve 8 is further opened, the amount of exhaust gas increases as the amount of intake air increases, and the exhaust turbo supercharger 4 is sufficiently rotationally driven to enter a supercharging state (on-turbo). As a result, the intake pressure in the intake manifold 2 gradually increases on the side higher than the atmospheric pressure, and the related fuel supply pressure also changes to become higher. As a result of this increase in fuel supply pressure, the breaker plate 28 continues to rotate in the retarding direction of the arrow 30 against the spring 37. Therefore, the ignition timing for the load in the on-turbo state is determined by the maximum delay control amount in the non-turbo state. Beyond this, the control is further delayed.

In this case, by selecting the spring constant of the spring 37, for example, the ignition timing characteristics as shown by the two-dot chain line in FIG. 3 can be controlled in conjunction with the load over the entire operating range of the engine.

The actual ignition timing in the engine is
This is the value obtained by subtracting the delay control amount due to an increase in engine load from the advance control amount due to the increase in engine speed, and the actual ignition timing when on turbo is higher than the actual ignition timing during non-turbo. As the supercharging increases, the delay control is further performed, and by this delay control during on-turbo, the point D of the maximum explosion pressure can be set to the maximum output of the engine while the ignition delay period is shortened due to the turbo supercharging. It is possible to maintain the angle approximately 10 degrees after dead center.

As described above, the present invention can automatically control the ignition timing in the engine to an appropriate value over the entire operating range from non-turbo to on-turbo when an electronically controlled fuel injection engine is configured with exhaust turbo supercharging. Therefore, it is possible to reliably prevent knocking and engine damage during turbocharging without setting the engine compression ratio low, and it is also possible to reliably achieve improved output and reduced fuel consumption over the entire operating range of the engine. Furthermore, the present invention has a simple configuration in which the fuel supply pressure to the fuel injection nozzle is introduced into the spring-equipped pressure actuating mechanism connected to the breaker plate in the distributor, so the installation space is saved. It also has the advantage of no increase.

[Brief explanation of the drawing]

Figure 1 is a pressure diagram showing the process of ignition and combustion of the air-fuel mixture, Figure 2 is a diagram showing the advance angle characteristics with respect to the engine speed, Figure 3 is a diagram showing the advance angle characteristics with respect to the engine load, and Figure 4 is a diagram showing the advance angle characteristics with respect to the engine load. The figure is a diagram of an embodiment of the present invention, and FIG. 5 is an enlarged sectional view taken along the line V-V in FIG. 4. 1...Engine, 4...Exhaust turbo supercharger, 5
...Exhaust turbine, 6...Blower compressor, 8...
...Throttle valve, 9...Supercharging passage, 12...Air flow meter, 16...Fuel injection nozzle, 15...
...fuel supply passage, 23...distributor,
24...Cam shaft, 25...Centrifugal advance mechanism, 28...
...Breaker plate, 31...Operating mechanism, 34
...Diaphragm, 37...Spring, 36...Diaphragm chamber.

Claims (1)

[Claims] 1. In a turbocharged engine in which the intake system is equipped with an exhaust turbosupercharger and fuel is supplied from a fuel injection nozzle in an amount corresponding to the amount of intake air into the engine, a centrifugal advance mechanism in the engine is provided. A distributor with a breaker plate is provided with a pressure-type actuation mechanism that operates the breaker plate in the advance/retard direction, and the pressure-type actuation mechanism is provided with a spring that biases the breaker plate in the advance direction. , a pressure chamber in the pressure-type actuating mechanism receives fuel supply pressure to the fuel injection nozzle,
An ignition timing control device for a turbocharged engine, characterized in that the breaker plate is introduced so as to operate in a retard direction against the spring at the fuel supply pressure.