JPS6316866Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a device that automatically controls the ignition timing of an internal combustion engine according to the engine load.

[Conventional technology and its problems]

In general, in the ignition combustion of the intake air-fuel mixture in an internal combustion engine, there is a so-called "ignition delay period" in which explosive combustion occurs after a certain period of time from the spark ignition by the ignition plug, and the shorter the ignition delay period, the longer the combustion Since the waveform becomes relatively gentle and stable, drivability is improved, and the absolute amount of HC and CO generated is reduced, the exhaust temperature rises, and the purification performance due to the oxidation reaction of the exhaust gas is improved. This effect is particularly significant in exhaust systems equipped with catalysts.

This ignition delay period varies depending on the combustion method, turbulent flow situation in the combustion chamber, air-fuel ratio, compression ratio, etc., but the ignition timing that minimizes this ignition delay period is generally the best. It exists around 20 degrees in front of the tea ceremony.

In addition, the optimal ignition timing (MBT) that minimizes the combustion consumption rate of the engine is further advanced than the ignition timing that minimizes the ignition delay period (approximately 40 degrees before top dead center).
In this case, there is a discrepancy between the ignition timing that aims to improve drivability and exhaust gas purification and the ignition timing that aims to improve fuel consumption, so it is not possible to control either one of the ignition timings. Both objectives cannot be achieved at the same time.

Therefore, the applicant of this case filed an earlier patent application (Japanese Patent Application No.
-87761, Japanese Patent Application Laid-open No. 54-22038), when negative pressure below atmospheric pressure acts on the pressure chamber of a distributor in an internal combustion engine, the ignition timing is advanced to the ignition timing that minimizes the ignition delay period. A negative pressure-operated sub-advance mechanism is connected to the sub-advance mechanism, and a negative pressure transmission passage from the downstream side of the throttle valve in the carburetor is connected to the pressure chamber of the sub-advance mechanism. The ignition timing advanced by the sub-advance mechanism is further adjusted when negative pressure is generated in the advance port, which is located slightly upstream of the closed position of the throttle valve in the carburetor. By connecting a negative pressure-operated main advance mechanism that advances the ignition angle, the ignition timing in the internal combustion engine can be set to the ignition timing that minimizes the ignition delay period in the medium and low load range, and the ignition timing can be adjusted to the ignition timing that minimizes the ignition delay period in the medium and low load range. In the range, the ignition timing is controlled to be close to the optimum ignition timing, thereby improving drivability in the medium and low load range and improving HC, CO, and high load.
A proposal was made to improve fuel consumption in the high rotation range.

[Problem that the invention attempts to solve]

However, in a dual advance mechanism including a main advance mechanism and a sub-advance mechanism as in this prior art, it is difficult to connect the main advance mechanism to only the negative pressure at the advance port. When the valve is slightly closer to the advance port, that is, in the operating range where the main advance mechanism starts advancing, the negative pressure generated at the advance port is small, and the negative pressure fluctuates and is unstable. As a result, the advance control by the main advance mechanism is not performed accurately as specified in the operating range where the throttle valve is slightly closer to the advance port, and the ignition timing in the internal combustion engine is not the optimal ignition timing in the operating range at that time. A phenomenon that causes a considerable delay occurs,
The problem was that the expected purpose could not be achieved reliably.

In order to solve this problem, it is considered that the main advance mechanism should be connected to the intake negative pressure where the negative pressure is stable. Since the large intake negative pressure also acts on the main advance mechanism in the operating range, there is a problem in that the ignition timing in that operating range becomes significantly overadvanced.

The present invention aims to solve the problems of the prior art without the occurrence of such problems.

[Means for solving problems]

To achieve this objective, the present invention provides a distributor in an internal combustion engine that advances the ignition timing to the ignition timing that minimizes the ignition delay period when negative intake pressure downstream of the throttle valve acts. A negative pressure-operated main mechanism is connected to a pressure-operated sub-advance mechanism, and further advances the ignition timing advanced by the sub-advance mechanism when negative pressure below atmospheric pressure acts on the pressure chamber. In an ignition timing control device including an advance mechanism, an intake negative pressure transmission passage from a downstream side of the throttle valve is connected to the pressure chamber of the main advance mechanism, and a throttle Negative pressure that applies negative intake pressure to the pressure chamber in the main advance mechanism when the valve opening is above a certain degree, and releases the pressure chamber in the main advance mechanism to the atmosphere when the throttle valve is below the opening degree. The structure is equipped with a switching valve.

[Functions and effects of the idea]

By configuring the present invention as described above, in the operating range below a certain opening of the throttle valve, the intake negative pressure acts only on the sub-advance mechanism, and in the operating range above this opening, it acts on both the sub-advance mechanism and Intake negative pressure can be applied to both the main advance angle mechanism, and unstable negative pressure at the advance port acts on the main advance angle mechanism in the medium and low load range of the internal combustion engine, as in the prior art. This prevents over-advance from occurring in the operating range below a certain opening of the throttle valve, and prevents over-advancing in the operating range near a certain opening of the throttle valve. This makes it possible to reliably prevent instability of angle control and insufficient advance angle.

Therefore, according to the present invention, the ignition timing in an internal combustion engine, which is the objective of the prior art, is adjusted to the ignition timing that minimizes the ignition delay period in the medium and low load range, and to the optimum ignition timing in the high load and high rotation range. This improves drivability in the medium and low load range and improves HC, CO and
This has the effect of reliably and accurately achieving an improvement in fuel consumption in a high load/high rotation range.

〔Example〕

The embodiments of the present invention are shown in the drawings (Fig. 1 and 2) below.
To explain the above, in the figure, reference numeral 1 indicates an intake manifold, reference numeral 2 indicates a carburetor with a throttle valve 3, and reference numeral 4 indicates a distributor equipped with a breaker plate 6 with a breaker arm 5. The breaker plate 6 has a negative pressure operated sub advance mechanism 7 which advances the ignition timing by rotating it in the direction of arrow A, and a negative pressure operated main advance mechanism 7. 8 are connected to each other via a connecting rod 9.

These two advance angle mechanisms 7 and 8 are configured such that a sub diaphragm case 12 and a main diaphragm case 13 each having a diaphragm 10 and 11 are directly connected via a partition plate 14. The diaphragm 11 has a connecting piece 17 that is pressed against the partition plate 14 by a main spring 16 in the pressure chamber 15.
is provided, and the connecting rod 9 from the breaker plate 6 is fixed to the sub-diaphragm 10 in the sub-diaphragm case 12, and is inserted into the connecting piece 17 through the pressure chamber 18, and is inserted into the insertion end thereof. In providing the flange 19 and engaging it with the connecting piece 17, a relatively weak sub-spring 20 is provided between the sub-diaphragm 10 and the connecting piece 17, and furthermore, the flange 19 and the inner part of the connecting piece 17 are connected to each other. A play of an appropriate interval S2 is provided in between in the advancing direction of the connecting rod 9, and a stopper piece 21 is provided in the pressure chamber 15 with an appropriate interval S1 between it and the back surface of the main diaphragm 11. .

The pressure chamber 1 in the sub-advance mechanism 7
5, and a pressure chamber 15 in the main advance mechanism 8
is connected to an intake negative pressure port 22 provided downstream of the throttle valve 3 in the carburetor 2 via intake negative pressure transmission passages 23 and 24, respectively, while the intake negative pressure port 22 and the main advance mechanism are In the intake negative pressure transmission passage 24 that connects the pressure chamber 15 at 8, there is an electromagnetic three-type negative pressure switching valve 2 between it and an atmosphere communication point 25 such as an intake air cleaner (not shown).
6 is provided in an electric circuit 28 connecting the solenoid of the negative pressure switching valve 26 and a power source such as a battery 27,
A switch 2 related to the opening degree of the throttle valve 3
9 is provided, and when the opening degree of the throttle valve 3 is below a certain level, the passage 24' on the intake negative pressure port 22 side of the intake negative pressure transmission passage 24 is closed, while the pressure chamber 15 is closed.
The side passage 24'' is communicated with a passage 30 to the atmosphere, but when the throttle valve 3 reaches a certain opening degree or more, the atmosphere passage 30 is closed and both passages 24', 2
4'' are configured to communicate with each other.

In this configuration, in the operating range where the throttle valve 3 is at a certain opening degree or less, the negative pressure switching valve 26 switches between the intake negative pressure port 22 and the pressure chamber 1 in the main advance mechanism 8.
5, the passage 24' on the intake negative pressure port 22 side is closed, while the passage 24'' on the pressure chamber 15 side is switched to communicate with the atmosphere, so this state In this case, the intake negative pressure does not act on the pressure chamber 15 in the main advance mechanism 8, and the intake negative pressure acts only on the pressure chamber 18 in the sub-advance mechanism 7. The ignition timing is advanced by the gap S2 by the sub-advance mechanism 7.

When the throttle valve 3 reaches the operating range above the certain opening degree, the negative pressure switching valve 26 is switched to apply negative intake pressure to the pressure chamber 15 in the main advance mechanism 8, and the main advance mechanism 8 is activated. Due to the intake negative pressure, the diaphragm 11 in the angle mechanism 8 is moved back by the distance S1 so as to come into contact with the stopper 21, while the intake negative pressure also acts on the sub-advance mechanism 7, so that the internal combustion engine is not operated in this operating range. The ignition timing in is advanced to a value obtained by adding the interval S2 in the sub-advance mechanism 7 to the interval S1 in the main advance mechanism 8, and at this time,
The interval S2 in the sub-advance mechanism 7 is set so that the ignition timing when the interval S2 becomes zero is the ignition timing that minimizes the ignition delay period, while the interval S2 in the main advance mechanism 8 S1
By setting the ignition timing to a value obtained by subtracting the ignition timing that minimizes the ignition delay period from the optimal ignition timing when the interval S1 becomes zero, the ignition timing of the internal combustion engine can be adjusted according to the throttle. In the operating range where the valve 3 is opened below a certain degree, the ignition timing is set to minimize the ignition delay period, and in the operating range where the valve 3 is opened above the certain opening, the ignition timing is set to the optimum ignition timing according to the intake negative pressure. Each of these can be automatically controlled.

Furthermore, in this case, when the throttle valve 3 reaches a certain opening degree, the negative pressure switching valve 26 applies the intake negative pressure to the pressure chamber 15 of the main advance mechanism 8 in addition to the pressure chamber 18 of the sub-advance mechanism 7. Since the ignition timing is advanced by both advance mechanisms 7 and 8, the control of the ignition timing may become unstable near a certain opening of the throttle valve 3, or the advance may become unstable. On the other hand, when the opening degree of the throttle valve 3 is below a certain level, the negative pressure switching valve 26 switches to apply negative intake pressure only to the pressure chamber 18 of the sub-advance mechanism 7. , since the advance angle control is performed only by the sub advance angle mechanism 7, the throttle valve 3
In the operating range below a certain opening degree, the ignition timing will not be overadvanced.

In addition, as a means for relating the negative pressure switching valve to the opening degree of the throttle valve, the negative pressure switching valve 26 is an electromagnetic type as in the above embodiment, and this is controlled by turning on the switch 29 provided for the throttle valve 3.・Instead of operating by turning OFF, as shown in FIG. By drilling a sensing port 31 at a certain opening position and connecting the sensing port 31 and the pressure chamber of the negative pressure switching valve 26a through a negative pressure passage 32, the throttle valve 3 can be opened to a certain opening position. The negative pressure generated at the sensing port 31 when opened may be used as an opening signal for the throttle valve 3 to switch the negative pressure switching valve 26a as in the above embodiment. be.

[Brief explanation of drawings]

The drawings show embodiments of the present invention; FIG. 1 is a diagram of the device of the first embodiment, FIG. 2 is an enlarged sectional view of the advance angle mechanism in FIG. 1, and FIG. 3 is a diagram of the device of the second embodiment. be. 1... Intake manifold, 2... Carburetor, 3...
...Throttle valve, 4...Distributor, 6
...Breaker plate, 7...Sub advance mechanism,
8... Main advance mechanism, 15... Pressure chamber in the main advance mechanism, 18... Pressure chamber in the sub advance mechanism, 23, 24... Intake negative pressure transmission passage, 2
6, 26a...Negative pressure switching valve.

Claims (1)

[Scope of utility model registration request] A negative pressure-operated sub-advance mechanism is connected to a distributor in an internal combustion engine, which advances the ignition timing to the ignition timing that minimizes the ignition delay period when negative intake pressure downstream of the throttle valve acts. In addition, the ignition timing control mechanism is connected to a negative pressure operated main advance mechanism which further advances the ignition timing advanced by the sub-advance mechanism when negative pressure below atmospheric pressure acts on the pressure chamber. In the control device, an intake negative pressure transmission passage from the downstream side of the throttle valve is connected to the pressure chamber of the main advance mechanism, and when the throttle valve is opened to a certain degree or more, the main advance is connected to the intake negative pressure transmission passage. The internal combustion engine is characterized by being provided with a negative pressure switching valve that applies negative intake pressure to the pressure chamber in the angle mechanism and opens the pressure chamber in the main advance mechanism to the atmosphere when the throttle valve opening is below the above-mentioned opening degree. Engine ignition timing control device.