JPS6235898Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition timing control device for an internal combustion engine equipped with a supercharger such as a turbocharger or a mechanical supercharger.

There is an optimal ignition timing (MBT) in internal combustion engines that maximizes engine output.
In addition, in the region close to the advance side of this optimum ignition timing, there is an ignition timing at the knocking limit where knocking will occur if the ignition timing is advanced further, while these optimum ignition timing and ignition timing at the knocking limit are It is known that the angle advances in proportion to the engine rotational speed and inversely proportional to the engine load.

In addition, supercharging an internal combustion engine can increase the charging efficiency of the engine and improve the output of the engine, but supercharging retards the optimal ignition timing and the ignition timing at the knocking limit compared to when no supercharging is performed. It will move to the side.

Therefore, as prior art, Japanese Patent Application Laid-Open No. 55-123364 and Japanese Patent Application Laid-open No. 55-125359 disclose a disc equipped with a centrifugal advance mechanism that advances the ignition timing in proportion to the engine speed. In the triviewer,
The pressure at the advance port, which is located slightly upstream from the closed position of the throttle valve, is introduced into the diaphragm operating mechanism for rotationally displacing the breaker plate. While the ignition timing is controlled in an advance direction in inverse proportion to the load by utilizing the increase in the vacuum side, the opening of the throttle valve increases and a supercharging state occurs, causing the pressure at the advance port to exceed atmospheric pressure. It is proposed that the ignition timing be controlled in a retarded direction as the ignition timing increases.

However, when automatically controlling the ignition timing in a supercharged internal combustion engine as in the prior art, the control characteristics of the ignition timing are set appropriately to the retard side from the ignition timing at the knocking limit.
While safety is ensured by providing an appropriate margin against knotting, the prior art has a structure in which the ignition timing changes immediately (without any time delay) in response to changes in the pressure of the advance port. Therefore, the automatically controlled ignition timing is always retarded from the knocking limit ignition timing at that time, and hence the optimum ignition timing, by the amount of safety against knocking, regardless of the operating state of the engine. It turns out. Therefore, since this relationship is maintained even when the engine accelerates, the ignition timing control according to the prior art hardly contributes to improving the acceleration performance of the engine.

The present invention is designed to retard the ignition timing in a supercharged internal combustion engine by using a diaphragm-type actuating mechanism installed in a distributor as the boost pressure increases. By retarding the ignition timing by an appropriate amount of time using a delay means provided in the boost pressure transmission passage to the diaphragm type actuating mechanism, the ignition timing is adjusted to the knocking limit at that time. This improves the output when the engine accelerates by temporarily bringing it closer to the ignition timing. but,
This is because knocking may occur during acceleration when the ignition timing abnormally approaches or exceeds the knocking limit ignition timing at that time. is carried out after supercharging reaches a certain value, that is, a pressure valve is provided in the supercharging pressure transmission passage in parallel to the delay means, and the pressure is maintained until the supercharging pressure reaches a certain value. When the valve is opened, the delay means is deactivated and the ignition timing is retarded to follow the increase in boost pressure without delay, but since the boost pressure exceeds the above-mentioned certain value, the pressure valve is closed. Therefore, by delaying the ignition timing in response to the increase in boost pressure by using the delay means, it is possible to prevent the ignition timing from approaching the knocking limit ignition timing abnormally during engine acceleration. This was done so that no one could do it or exceed it.

Below, we will explain the drawings of an embodiment in which the present invention is applied to an internal combustion engine with a turbocharger. Each supercharger is shown, and a surge tank 6 for eliminating pulsation and a carburetor 8 with a throttle valve 7 are installed in a supercharging passage 31 connecting the discharge side of the supercharger 4 and the intake manifold 2. An air cleaner 9 is connected to the suction side of the supercharger 4, and an inlet side of the exhaust turbine 5 is connected to the exhaust manifold 3 via an exhaust passage 10, and an outlet side of the exhaust turbine 5 is connected to the exhaust manifold 3 through an exhaust passage 10. An exhaust pipe 11 to the atmosphere is connected to each side.

Reference numeral 12 denotes a distributor for controlling the ignition timing of the engine 1, and the distributor 12 includes a camshaft 13 that rotates around the crankshaft (not shown) of the engine. 3
A centrifugal advance mechanism 14 having advance characteristics as shown by a solid line C in the figure is provided, and a camshaft 1 is provided inside.
A breaker plate 17 having a breaker arm 16 with a contact 15 that turns on and off with the rotation of step 3.
is provided, and when the breaker plate 17 rotates in the direction of arrow A, the ignition timing is controlled in an advanced direction, and when it rotates in the direction of arrow B, the ignition timing is controlled in a retarded direction.

Reference numeral 18 denotes a diaphragm type actuation mechanism attached to the side surface of the distributor 12;
consists of a diaphragm case 19, a diaphragm 21 connected to the breaker plate 17 via a connecting rod 20, and diaphragm chambers 22 and 23 formed on both sides of the diaphragm 21. A spring 24 is provided in the other diaphragm chamber 23 to resist movement of the diaphragm 21 in an advanced direction from the position shown, and a spring 25 is provided in the other diaphragm chamber 23 to resist movement of the diaphragm 21 in a retard direction from the position shown. It is provided in contact with the diaphragm 21, the other diaphragm chamber 23 is connected to the atmosphere, and the one diaphragm chamber 22 is connected to the atmosphere.
is connected to an advance port 26 provided in the carburetor 8 slightly upstream from the closed position (idle position) of the throttle valve 7 via a supercharging pressure transmission passage 27.

Then, in the supercharging pressure transmission passage 27 from the advance port 26 to one diaphragm chamber 22 of the diaphragm type actuation mechanism 18, until the pressure of the advance port 26 reaches a certain value (for example, 300 mmHg) equal to or higher than atmospheric pressure, A pressure valve 28 is provided to shut off the supercharging pressure transmission passage 27, while the pressure valve 28 is provided in the supercharging pressure transmission passage 27.
8, a check valve 3 is provided in the bypass passage 29 and is configured to open only in the direction opposite to the throttle orifice 30 and one diaphragm chamber 22, that is, in the direction of the advance port 26.
1 is provided in parallel with the delay means 32.

In this configuration, the pressure at the advance port 26 is approximately atmospheric pressure when the throttle valve 7 is in the idle position, so the ignition timing with respect to the rotational speed is a characteristic curve C shown by the solid line in FIG. When the port 26 is opened all the way, the greatest negative pressure will be on the vacuum side.
This large negative pressure causes the check valve 31 in the delay means 32 in the boost pressure transmission passage 27 to open and the pressure valve 28 to open.
As a result of the opening of Since the engine is rotated, the ignition timing is in the most advanced state, and the control characteristic of the ignition timing with respect to the rotational speed at this time becomes a characteristic curve D shown by a two-dot chain line in FIG. When the throttle valve 7 is opened beyond the advance port 26, the negative pressure in the advance port 26 rises to approach atmospheric pressure, and in response, the breaker plate 17 rotates from the maximum advance position to the retard direction. The timing characteristic curve approaches the characteristic curve D shown by the solid line in FIG. 3, and the ignition timing is gradually retarded as the throttle valve 7 opens and as the engine load increases. Throttle valve 1
7 is opened further, the amount of exhaust gas from the engine increases, the supercharger 4 is sufficiently rotated and shifts to the supercharging state, and the pressure at the advance port 26 gradually increases as the supercharging increases. Since the breaker plate 17 is rotated in the retard direction against the spring 25 due to the supercharging pressure exceeding the atmospheric pressure, the ignition timing is further adjusted than when the pressure at the advance port 26 is below the atmospheric pressure. The ignition timing will be retarded as the boost pressure increases, and the control characteristics of the ignition timing with respect to the rotational speed at this time will be as shown in the solid line as shown in the characteristic curve E shown by the dashed line in Fig. 3. As a result, the ignition timing of the engine during supercharging follows the shift of the ignition timing at the knocking limit to the retard side due to supercharging.
In this case, the control characteristic value of the ignition timing for various operating conditions of the engine is adjusted appropriately to provide a safety factor for the ignition timing at the knocking limit under each operating condition of the engine. It is set to be located on the retard side by the angle.

Also, when the throttle valve 7 is closed, the pressure in the advance port 26 drops, and this pressure drop is transmitted through the pressure valve 28 when the pressure valve 28 is open, and through the delay means 32 when the pressure valve 28 is closed. Since the signal is immediately transmitted to one diaphragm chamber 22 when the check valve 31 is opened, the ignition timing is advanced without delay as the throttle valve 7 is closed and the engine load is reduced. .

In the supercharging state, when the supercharging pressure increases and reaches the set pressure in the pressure valve 28, the pressure valve 28 closes, and the subsequent increase in supercharging pressure is controlled via the delay means 32. It is transmitted to the diaphragm type actuation mechanism 18, but in this case, during slow acceleration when the throttle valve 7 is opened slowly, the boost pressure at the advance port 26 increases slowly, and the pressure increase is caused by the throttle orifice. The ignition timing is transmitted to one of the diaphragm chambers 22 without being subject to the delay restriction by 30, and the ignition timing is retarded to follow the increase in supercharging pressure as described above.

However, when the throttle valve 7 is suddenly opened and the vehicle is suddenly accelerated, the supercharging pressure at the advance port 26 increases rapidly.
When the check valve 31 in the delay means 32 is closed, this rapid increase in boost pressure is delayed and regulated by passing through the throttle orifice 30 and transmitted to one diaphragm chamber 22, and the ignition timing is controlled in the retarded direction. In other words, as the boost pressure increases, the ignition timing at the knocking limit shifts to the retard side, which precedes the retard control of the ignition timing. The actual ignition timing in the engine is
While the supercharging pressure is rising due to sudden acceleration of the engine, the pressure in one diaphragm chamber 22 becomes balanced with the supercharging pressure in the advance port 26 after the ignition timing approaches the knocking limit for the current supercharging pressure. At this point, the ignition timing has a predetermined safety factor with respect to the ignition timing at the knocking limit. This makes it possible to improve the output when the engine accelerates.

The effect of temporarily bringing the ignition timing closer to the knocking limit ignition timing corresponding to the boost pressure at that time by the delay means 32 during acceleration of the engine is caused by the pressure provided in parallel to the delay means 32. After the valve 28 is closed, the delaying action by the delay means 32 is not performed until the boost pressure reaches the set pressure of the pressure valve 28. Therefore, the ignition timing is changed depending on the increase in the boost pressure. Following the shift of the ignition timing at the knocking limit to the retarded side, this is controlled to be retarded while maintaining a certain safety factor.In other words, the ignition timing in the engine is At the beginning of rapid acceleration of the engine, the ignition timing does not approach the knocking limit corresponding to the boost pressure at that time, and when the engine accelerates and the boost pressure exceeds the set value of the pressure valve 28, that is, When the ignition timing is retarded to a certain extent as the boost pressure increases, the ignition timing approaches the knocking limit, so the ignition timing is retarded from an early stage when the engine is accelerating. As in the case where the control to the side is delayed by the delay means 32, the ignition timing may abnormally approach the knocking limit ignition timing during acceleration, or exceed this and enter the knocking region. Therefore, the risk of knocking can be reliably avoided.

Therefore, the present invention has the effect of improving acceleration performance in a supercharged internal combustion engine without causing knocking.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view taken from the side of FIG. 1, and FIG. 3 is a diagram showing ignition timing control characteristics. 1... Engine, 4... Turbo supercharger, 5... Exhaust turbine, 8... Carburetor, 7... Throttle valve,
12...Distributor, 18...Diaphragm type actuation mechanism, 27...Supercharging pressure transmission passage, 28
... Pressure valve, 29 ... Bypass passage, 30 ... Throttle orifice, 31 ... Check valve, 32 ... Delay means.

Claims (1)

[Scope of utility model registration request] A supercharged internal combustion engine equipped with a diaphragm-type actuation mechanism that retards the ignition timing in response to an increase in boost pressure to the engine, in a distributor for controlling the ignition timing of an internal combustion engine equipped with a supercharger. In the engine, a pressure valve is provided in the boost pressure transmission passage to the diaphragm type actuating mechanism, and the pressure valve is configured to shut off the pressure transmission passage when the boost pressure reaches a certain pressure; An ignition timing control device for a supercharged internal combustion engine, characterized in that a bypass passage provided for the pressure valve is provided with a delay means for delaying and transmitting pressure only in the direction of the distributor.