JPS6052315B2 - Ignition timing control device for turbocharged engines - 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, that is, an exhaust turbo supercharger, driven by an exhaust gas turbine.

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. Next, the maximum explosion pressure is reached at point D through the direct combustion period of CD, and the process of reaching the afterburning period of DE takes place, and the point D of the maximum explosion pressure is set after the top dead center of the crank angle (
It is known that the maximum output of the engine can be obtained when the engine is set to about 100 (ATDC).

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 mixer that occupies the intake stroke volume under standard conditions, and the charging efficiency is proportional to the rotation speed. Since the ignition delay period is inversely proportional to the rotation speed and directly proportional to the load, the ignition delay period increases in proportion to the rotation speed, and increases in inverse proportion to the load. The relationship is getting shorter.

Therefore, in conventional ordinary engines (those without a turbocharger), a centrifugal advance mechanism is installed in the distributor to determine the rotation speed when the negative pressure in the intake pipe is set to atmospheric pressure. For example, the characteristics of the ignition timing for
While controlling the load as shown by the solid line in the figure,
The distributor is equipped with a vacuum advance mechanism that uses the intake pipe negative pressure as an input signal, and the characteristics of the ignition timing when the rotational speed is kept constant are controlled, for example, as shown by the solid line in Figure 3. There is.

On the other hand, an exhaust gas turbo supercharger has the advantage of being able to use the energy contained in the exhaust gas from the engine to improve the engine's output, but it requires a considerable amount of exhaust gas energy to drive the exhaust gas turbine. In an exhaust turbocharged engine, turbocharging is not performed at low speeds and low load ranges where the amount of exhaust gas from the engine is small, and the engine is in a so-called non-turbo state.
Turbocharging (on-turbo) is performed in the load range, and in the turbocharging state, the charging efficiency increases rapidly, and this rapid increase in charging efficiency shortens the ignition delay period T.
tends to become shorter more rapidly than when the load increases in a non-turbo state.

Therefore, applying the conventional centrifugal and vacuum advance mechanism to this turbocharged engine means that with the vacuum advance mechanism, the ignition is controlled in the advance direction as the engine speed increases. Since the timing cannot be controlled in the retarded direction in the turbocharging region, the point D of maximum explosion pressure in the turbocharging state is at or near top dead center due to the shortening of the ignition delay period due to supercharging. or, in some cases, before top dead center (BTDC). This shift of the maximum explosion pressure point toward top dead center not only causes a sudden drop in engine output, but also increases noise due to knocking, and in some cases may cause engine damage. Engines that can withstand this damage will be significantly heavier. Therefore, in order to prevent the maximum explosion pressure point D from shifting toward top dead center during turbocharging, the control characteristics of the ignition timing with respect to the rotation speed shown in FIG.
It may be possible to move parallel to the retard direction by the amount that the ignition delay period T is shortened during turbocharging as shown by the two-dot chain line, but if this is done, the turbosupercharger will not operate in non-turbo mode, that is, the turbosupercharger will not operate. Otherwise, at low rotation speeds and low loads where the engine is not in a state where it can operate satisfactorily, the optimum ignition timing may not be controlled, resulting in negative results such as a decrease in output and an increase in fuel consumption.

Furthermore, when controlling the ignition timing of a turbocharged engine using the conventional method described above, it may be 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 the ζ output of the engine will decrease over the entire operating range.

The present invention provides a turbo-supercharged edge engine equipped with a carburetor (throttle valve in the case of a fuel injection engine) upstream of a blower compressor of a turbo-supercharger. When using a two-channel system, it is in the non-turbo region when air is taken only from the primary side, and it shifts to the turbocharged region when air is drawn from the primary side and then from the secondary side.
The ignition timing is controlled in the advance direction in proportion to the engine speed, and in the non-turbo range, the optimum ignition timing is controlled further in accordance with the load by changing the pressure of the throttle boat on the primer side throttle valve. On the other hand, in the on-turbo range, the ignition timing is controlled in the advance direction according to the rotation speed, and the delay control is applied to the flow from the blower J-compressor to the engine by switching the switching valve linked to the throttle valve on the secondary side. By controlling the turbocharging pressure, the ignition timing during on-turbo is controlled in the retard direction by an amount commensurate with the shortening of the ignition delay period during turbocharging.

Next, an example of the present invention will be explained with reference to the drawings. In the drawing, 1 is an engine having an intake manifold 2 and an exhaust manifold 3, 4 is an exhaust turbine 5 and a blower compressor 6.
7 indicates a muffler or a catalytic converter that discharges exhaust gas into the atmosphere, and a collection part 8 of the intake manifold 2 is connected to the discharge side of the blower compressor 6 via an intake passage 9. connected, blower compressor 6
The primary side 11 and the secondary side 12 are on the intake side of the
A dual carburetor 10 (a dual throttle valve in the case of a fuel injection engine) and an air cleaner 13 having
The exhaust side of the exhaust turbine 5 is connected to the muffler 7 via an exhaust pipe 14, and the inlet side of the exhaust turbine 5 is connected to the exhaust manifold 3 via an exhaust passage 15.

Both the primary side 11 and the secondary side 12 of the dual carburetor 10 (double throttle valve in the case of fuel injection system) are equipped with throttle valves 16 and 17, respectively, and the primary throttle valve 16 is connected to the accelerator pedal (
(not shown), and the secondary throttle valve 17 is opened and closed by the primary throttle valve 16 as is conventionally known.
The primary throttle valve 16 is connected to the primary throttle valve 16 so that it will automatically open in conjunction with this if it does not open to a certain extent.

Reference numeral 18 denotes a distributor which is equipped with a centrifugal advance angle mechanism 20 having an advance angle characteristic, for example, as shown by the solid line in FIG. A breaker plate 22 having a breaker arm 21 equipped with a contact point 2'' that turns 0N-0FF as the camshaft 19 rotates is provided inside the breaker plate 22.
When the breaker plate 22 rotates in the direction of the arrow 23, the ignition timing advances, and when the breaker plate 22 rotates in the direction of the arrow 24, the ignition timing retards.

Reference numeral 25 denotes a diaphragm type actuation mechanism for rotating the breaker plate attached to the side surface of the distributor 18. The actuation mechanism 25 includes a diaphragm case 26 and a diaphragm 28 connected to the breaker plate 22 via a connecting rod 27.
and diaphragm chambers 29 and 30 formed on both sides of the diaphragm chambers 29 and 30, in which a spring 31 that resists movement of the diaphragm 28 from the illustrated position in the advance angle direction is placed in the diaphragm chamber 29 in the other diaphragm chamber. 30 are each provided with a spring 32 abutting the diaphragm 28 to resist movement of the diaphragm 28 in the retarded direction from the illustrated position.

In this case, in another embodiment, as shown in FIG. 6, a spring 32'' serving as a resistance in the retard direction is provided in one diaphragm chamber 29, with both ends engaged with the case 26 and the diaphragm 28. Also, as shown in FIG. 7, a spring 3'' in one diaphragm chamber 29 is provided with one end attached to the case 26 and the other end attached to the diaphragm 28, so that the spring 3'' is attached to the diaphragm 28 in the advancing direction of the diaphragm 28. For the movement of the spring 3
In other words, one spring 3'' is used to advance and retard the movement of the diaphragm 28 in the retard direction so that the compressive force of the spring 3'' acts as a resistance, and the tensile force of the spring 3'' acts as a resistance to the movement of the diaphragm 28 in the retard direction. The scuttle port 33 is located slightly upstream of the closed position of the throttle valve 16 on the primary side 11 of the carburetor 10 (double throttle valve in the case of a fuel injection system), and is used as an intake port. Intake pipe boats 34 are provided at appropriate locations in the passage 9, and throttle boats 33
The passage 35 from the intake pipe boat 34 and the passage 36 from the intake pipe boat 34 are connected to the passage 37 to the diaphragm chamber 29 of the actuating mechanism 25 in the distributor 18. The throttle valve 17 on the secondary side 12 of the throttle valve (type throttle valve) is provided with a switching valve 39 that is linked via an interlocking mechanism 38 such as a linking rod, and when the secondary throttle valve 17 is closed, the passage 35 from the throttle boat 33 is However, when the secondary throttle valve 17 is opened, the passage 36 from the intake pipe boat 34 is switched to communicate with the passage 37.

In this configuration, the ignition timing of the engine is controlled by the centrifugal advance mechanism 20 in the distributor 18 as the engine speed increases along the characteristic shown by the solid line in FIG. Controlled in the direction of travel.

On the other hand, in the region where the opening degree of the primary throttle valve 16 is small, the secondary throttle valve 17 does not open yet and the amount of intake air is small, so the amount of exhaust gas is small and the rotation of the turbo supercharger 4 is slow, so the turbo is overloaded. It has not reached the supply range. Throttle boat 3 on the primary side 11 of the carburetor 10 (double throttle valve in case of fuel injection system)
The pressure in No. 3 is atmospheric pressure during idling when the primary throttle valve 16 is closed;
A high negative pressure is created by slightly opening the diaphragm chamber 29 of the actuating mechanism 25 through passages 35 and 37.
The diaphragm 28 is pulled into one diaphragm chamber 29 against the spring 31 or 3'', and the breaker plate 22 is rotated in the advance direction of the arrow 23, thereby advancing the ignition timing. However, since the pressure on the vacuum side of the throttle boat 33 gradually approaches atmospheric pressure as the primary throttle valve 16 opens, the breaker plate 22 The amount of advance angle is decreased by the spring 31 or 3', and the ignition timing is sequentially rotated in the retard direction.Therefore, the ignition timing by the breaker plate 22 is determined by the free length and spring constant of the spring 31 or 3'. Since the characteristics can be controlled as shown by the solid line in Figure 3, the actual ignition timing in the engine is the sum of the amount of advance control due to an increase in engine speed and the amount of advance that is decreased as the load increases. In other words, in the non-turbo range, the ignition timing is controlled in the same way as a normal engine without a turbocharger.Then, when the primary throttle valve 16 is further opened, this In conjunction with this, the secondary throttle valve 17 also opens, the amount of exhaust gas increases, and the turbo supercharger 4 is sufficiently rotationally driven to shift to a supercharging state.

In conjunction with the opening of the secondary throttle valve 17, the switching valve 39 is switched so that the passages 36 and 37 are communicated with each other. Then, the supercharging pressure of the intake pipe boat 34 acts on the diaphragm chamber 29 in the actuating mechanism 25, and the diaphragm 28
The spring 32, 32' or 3' is pressed in the direction of the other diaphragm chamber 30 against the force of the breaker plate 2.
2 is rotated in the retard direction of the arrow 24. Therefore, as the turbo charge increases in the turbo charge region, the ignition timing can be controlled in the retard direction.
"By setting the free length and spring constant, it is possible to control the characteristics as shown by the two-dot chain line in Figure 3, so the actual ignition timing in the engine is delayed as the supercharging increases, and this control By this, the point D of the maximum explosion pressure can be maintained near about 10 degrees after top dead center, where the maximum output of the engine is obtained, in order to shorten the ignition delay period during turbocharging. According to the invention, the ignition timing in a turbocharged engine can be accurately and automatically controlled over the entire operating range from non-turbo to on-turbo, thereby eliminating knocking and engine knocking during turbocharging without setting the engine compression ratio low. Damage to the engine can be reliably prevented, and maximum output and fuel efficiency can be obtained over the entire operating range.Moreover, the diaphragm of the actuating mechanism in the present invention only needs to be provided with springs in its advance and retard directions. Therefore, not only is the structure extremely simple, it can operate reliably with few failures, it can be provided at low cost, and the control characteristics can be set arbitrarily to suit the engine using the spring.
Furthermore, since the ignition timing is switched from non-turbo to on-turbo by opening the secondary throttle valve, the ignition timing can be switched accurately.

[Brief explanation of the drawing]

Figure 1 is a pressure diagram showing the process of ignition and combustion of air-fuel mixture.
The figure shows the advance angle characteristics with respect to the engine speed.
The figure shows advance angle characteristics with respect to load, Figure 4 is a diagram of the device according to the embodiment of the present invention, Figure 5 is an enlarged cross-sectional view taken from -V in Figure 4, and Figures 6 and 7 are other embodiments. FIG. 1... Engine, 4... Turbo supercharger,
5...Exhaust turbine, 6...Blower compressor, 9...Intake passage, 10...Double carburetor, 11...Primary Side, 12...
...Secondary side, 16, 17...Throttle valve, 18...Distributor, 19...
...Camshaft, 20...Centrifugal advance mechanism, 21...
...Breaker arm, 2 "...Contact, 22...
・Breaker plate, 25...Operating mechanism, 2
8...Diaphragm, 29...Diaphragm chamber, 31, 32, 32'', 3''...Spring,
33...Throttle boat, 39...Switching valve.

Claims (1)

[Claims] 1. In a turbocharged engine that is equipped with a dual throttle valve on the suction side of a blower compressor in an exhaust turbocharger, the distributor with a centrifugal advance mechanism in the engine has its breaker plate advanced. Equipped with a diaphragm type operating mechanism that operates in the angle and retard directions,
The diaphragm in the actuation mechanism is provided with a spring that acts in both advance and retard directions, and connects the diaphragm chamber with a throttle port provided slightly upstream of the closed position of the primary throttle valve in the throttle valve. A turbo, characterized in that a switching valve is provided in the conduit, the switching valve connecting the diaphragm chamber to the intake passage leading from the blower compressor to the engine in conjunction with opening of a secondary throttle valve in the throttle valve. Ignition timing control device for supercharged engines.