JPS5913344Y2 - Engine ignition timing control device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an ignition timing control device that controls the ignition timing of an automobile engine in accordance with atmospheric pressure.

A negative pressure advance mechanism installed in the distributor of an automobile engine controls ignition timing according to the negative pressure of the atpan support located slightly upstream of the carburetor throttle valve when it is fully closed.

By the way, as you go to higher altitudes, the atmospheric pressure becomes lower, and the negative pressure in the atpan support gradually decreases, causing the engine to be retarded and causing a lack of engine output.

Therefore, by using a negative pressure advance mechanism with two diaphragms, the main diaphragm is constantly applied with atpan support negative pressure to perform normal ignition timing control, and the sub diaphragm is used to perform normal ignition timing control, for example, at 1000 m or more. A system was devised in which the ignition timing was advanced by a predetermined amount by applying negative pressure in the intake pipe.

However, this advance mechanism requires a complicated structure, and
At 1,000 m or more, the ignition timing is controlled to a relatively desirable level by the negative pressure acting on the subdiaphragm, but at 1,000 m or more,
Below m, there is a drawback that the same problem as before occurs.

In view of the above points, the present invention uses an altitude compensation sensor that gradually reduces the opening area as the atmospheric pressure decreases to adjust the negative pressure in the chamber of the negative pressure advance mechanism, into which the atpan support negative pressure is introduced, according to the atmospheric pressure. It is an object of the present invention to provide an ignition timing control device that controls the ignition timing by controlling the ignition timing, thereby making it possible to obtain advance characteristics according to atmospheric pressure using a negative pressure advance mechanism of a single diaphragm.

In addition, there is a known device that has a needle valve that is linked to a bellows to variably control the opening area depending on the atmospheric pressure, but if you want to achieve a certain level of control accuracy with this type of device, the needle valve must be adjusted to a high level. It has the disadvantage that it must be manufactured with precision and is therefore very difficult to manufacture.

Another object of the present invention is to provide a sensor with a new structure that allows variable control of the opening area without using a needle valve, that is, a sensor that is easy to manufacture.

The present invention will be described below with reference to embodiments shown in the drawings.

1 is an altitude compensation sensor, and an atmospheric pressure chamber 4 formed by a cover 2 having an atmospheric hole 2a and a cup-shaped case 3 includes:
It has a bellows 5 made of a vacuum-sealed spring material, and the bellows 5 is attached to the case 3 with screws 6.

Further, a plate 7 held in a predetermined position by screws or the like (not shown) is disposed within the atmospheric pressure chamber 4, and a passage 7a is formed in the plate 7.

This passage 7a can communicate with the atmospheric pressure chamber 4 and is connected via a pipe 8 to a negative pressure advance device, which will be described later, and is connected to an elastic metal reed valve 10 fixed to the plate 7 with a screw 9. It is opened and closed.

A shaft 11 is installed approximately in the center of the plate 7 and at a position facing the bellows 5, and this shaft 11 is biased toward the bellows 5 by a spring 12 and
The reed valve 10 is designed to follow the expansion and contraction of the reed valve 10.
The free end of follows the displacement of the shaft 11.

A carburetor 30 forms the air-fuel mixture to be supplied to the engine E, and has a primary main nozzle 32 and a throttle valve 33 in the primary bore 31. When the throttle valve 33 is in the fully closed position, the carburetor 30 Atopan support 3 located upstream
4 is formed.

A distributor 50 supplies current to a spark plug attached to the engine E at a predetermined timing, and has a negative pressure advance mechanism 500 that adjusts the current supply timing, that is, the ignition timing, depending on the operating condition.

This mechanism 500 includes a rod 501 whose one end is connected to a movable base plate 51 of the distributor 50;
A diaphragm 502 connected to the other end, a negative pressure chamber 503 formed in one side of the diaphragm 502, and a negative pressure chamber 5
This negative pressure chamber 503 is connected to the atpan support 34 through a throttle 60.
It is connected to the pipe 8 (passage 7a).

The operation will be explained below.

If the car is running on low ground (flat land), sensor 1
is in the state shown.

That is, since the pressure in the atmospheric pressure chamber 4 is high, the bellows 5 contracts, the shaft 11 moves upward in the figure, the free end of the reed valve 10 is pushed up, and the passage 7a is opened.

Therefore, the negative pressure of the negative pressure chamber 503 into which the negative pressure of the atpan support 34 of the capretor 30 is introduced via the throttle 60 is:
It is weakened by the air bled by an amount corresponding to the area of the passage 7a.

Here, by weakening the set load of the spring 504 of the negative pressure advance mechanism 500 by an amount equivalent to the amount weakened by the air bleed, the advance angle characteristic similar to the conventional one can be maintained according to the negative pressure of the atpan support 34. can get.

When the vehicle moves to a high altitude, the negative pressure in the atpan support 34 decreases as well as the atmospheric pressure, so the ignition timing generally shifts to the retarded side compared to the low altitude.

However, in the device of the present invention, the bellows 5
Because of the expansion, the shaft 11 and the free end of the reed valve 10 gradually descend, and as the inclination of the reed valve 10 changes, the opening area of the passage 7a gradually becomes smaller as the atmospheric pressure decreases, and the amount of bleed air decreases. and negative pressure chamber 50
The negative pressure in step 3 will gradually rise.

Therefore, the angle is advanced as the atmospheric pressure decreases.

It goes without saying that the ignition timing is controlled according to the change in the negative pressure of the atpan support 34 at this time.

Note that a plurality of bellows 5 may be stacked, and either a flat plate type or a corrugated plate type may be used for the bellows 5.

Furthermore, although the negative pressure of the attopan support 34 was used in the above embodiment, it is also possible to use other negative pressures.

As explained above, in this invention, the negative pressure in the negative pressure chamber of the negative pressure advance mechanism is adjusted by the altitude compensation sensor that variably controls the opening area according to the atmospheric pressure. Advance angle characteristics corresponding to the negative pressure of the negative pressure source can also be obtained, and insufficient engine output at high altitudes can be resolved.

In addition, it is only necessary to add an altitude compensation sensor to a commonly used ignition timing control device having a one-diaphragm type negative pressure advance mechanism, and therefore it is extremely easy to implement.

Furthermore, since the altitude compensation sensor does not use a needle valve, it is easy to manufacture, and a predetermined control accuracy can be easily obtained.

Furthermore, if an engine ignition timing adjustment device such as the one of the present invention is used, even if the air pressure becomes lower and lower and the plate-like valve body completely closes the passage, even if the air pressure drops further and the diaphragm expands. Since the movable end of the plate-shaped valve body is locked at an intermediate position of the shaft, the shaft can be further displaced.

Therefore, the extension of the diaphragm is absorbed by the shaft by the distance between the diaphragm-side end of the shaft, the shaft, the plate-shaped valve body, and the locking location.

If the shaft is not displaceable in this case, then
There is a risk that the diaphragm will be damaged due to the reaction force acting on it due to its own expansion, but as mentioned above, in the present invention, the diaphragm is connected between the diaphragm side end of the shaft and the point where the shaft engages with the plate-shaped valve body. If the distance is long enough, there is no danger of this happening at all.

Furthermore, since the present invention uses a plate-shaped valve body to increase or decrease the opening area of the passage, the opening area of the passage can be changed linearly, which has the advantage of improving control accuracy. has.

[Brief explanation of the drawing]

The figure is a schematic cross-sectional view showing an embodiment of the device of the present invention. 1... Altitude compensation sensor, 5... Bellows, 7a...
- Passage, 10... Reed valve forming a valve body, 34... Atpan support forming a negative pressure source, 50... Taste repeater, 500... Negative pressure advance mechanism, 502... Diaphragm, 503...Negative pressure chamber.

Claims (1)

[Scope of utility model registration request] In an ignition timing control device for an engine, which includes a negative pressure advance mechanism that introduces negative pressure from a negative pressure source of the engine into a negative pressure chamber formed by one diaphragm and controls the ignition timing according to the negative pressure. a bellows that expands as the atmospheric pressure decreases and contracts as the atmospheric pressure increases; a shaft that is connected at one end to the bellows side and follows the expansion and contraction of the bellows; and a shaft that extends in the direction of contraction of the bellows. a biasing means for biasing; a plate-shaped valve body having one end fixed in a predetermined position and the other end locked at an intermediate position of the shaft; and the plate-shaped valve body opening as the pressure decreases. a passage whose area is gradually decreased and whose opening area is gradually increased as the atmospheric pressure rises, one end of which communicates with the negative pressure chamber of the negative pressure advance mechanism, and the other end of which is open to the atmosphere; An ignition timing control device for an engine, characterized in that when the plate-shaped valve body completely closes the passage, the other end of the shaft is in a state where it can be further displaced.