JPS633432Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to an ignition timing control device for an internal combustion engine, and in particular, the two
The present invention relates to an ignition timing control device for an internal combustion engine that reliably performs advance control using a stage method, achieves the required ignition timing of the engine, increases output, and improves drivability.

Generally, an internal combustion engine has an optimal ignition timing that matches various conditions such as its operating state and set air-fuel ratio. In order to satisfy the required ignition timing of such an engine, an ignition timing control device is provided to obtain an ignition timing that meets the conditions. Conventional ignition timing control devices include those with a single boost controller and those with two boost controllers, but both control the ignition timing using only the negative pressure in the intake passage. However, there was no advance control based on negative pressure in the intake guide passage, and ideal advance control over the entire load range from low load to high load was not possible.

Therefore, the purpose of this invention is to operate the vacuum advance device using the negative pressure in the intake passage and the negative pressure in the intake guide passage, thereby achieving the required ignition timing and improving the output by reliably controlling the advance angle of the engine. The object of the present invention is to realize an ignition timing control device for an internal combustion engine that improves drivability and is easy to manufacture.

In order to achieve this objective, this invention has been proposed in an ignition timing control device for an internal combustion engine that has a vacuum advance device that retards the ignition timing in response to an increase in load. The first boost controller of the vacuum advance device is located downstream of the carburetor throttle valve when the opening is above a predetermined opening, and is located upstream of the carburetor throttle valve when the opening is less than a predetermined opening. A second negative pressure of the second boost controller of the vacuum advance device is located in the middle of the intake guiding passage which communicates with the first negative pressure passage, has an inlet upstream of the carburetor throttle valve, and opens and ends near the intake valve. It is characterized by having passages that communicate with each other.

Embodiments of this invention will be described in detail below based on the drawings.

1 and 2, 2 is a carburetor bench lily, 4 is a carburetor throttle valve, 6 is an intake passage, 8 is an intake valve, 10 is a combustion chamber, 12 is an exhaust valve, and 14 is an exhaust passage. The distributor 16 includes a power distributor, a interrupter, and an advance device, and the vacuum advance device 17 of the advance device includes a first boost controller 18 and a second boost controller 20.

The first boost controller 18 includes a first diaphragm chamber 22 as a main diaphragm chamber, a first diaphragm 24, and a first biasing means 26 that biases the first diaphragm 24 in the direction of arrow A, which is a retardation direction.
It consists of Similarly, the second boost controller 20 also has a second boost controller which is a sub diaphragm chamber.
It is comprised of a diaphragm chamber 28, a second diaphragm 30, and a second biasing means 32 that biases the second diaphragm 30 in the direction of arrow A, which is the retardation direction. An engaging portion 34 is fixed to the first diaphragm 24, and one end of a rod 36 is engaged with the engaging portion 34. The second diaphragm 30 is fixed to the other end of the rod 36. However, the rod 36
By moving in the axial direction, that is, in the directions of arrows A and B, the ignition timing is retarded.

A first negative pressure passage 38 is provided which communicates with the first diaphragm chamber 22 of the first boost controller 18, and this first negative pressure passage 38 communicates with an advance port 40 provided in the intake passage 6. When forming this advance port 40, the carburetor throttle valve 4
When the opening degree is above a predetermined opening degree, the advance port 40 is located downstream of the upper end of the carburetor throttle valve 4, and when the opening degree is less than the predetermined opening degree, the advance port 40 is advanced to the intake passage 6 position, which is upstream of the upper end of the carburetor throttle valve 4. A port 40 is provided.

Further, a portion of the intake passage 6 upstream of the carburetor throttle valve 4 and a portion immediately upstream of the intake valve 8 are communicated through an intake guide passage 42 . This intake guide passage 42 starts at an opening upstream of the carburetor throttle valve 4 as an introduction port 44, and ends at an opening immediately upstream of the intake valve 8 as an intake guide nozzle 46. A second negative pressure passage 48 is branched and provided in the middle of the intake guide passage 42, and the second negative pressure passage 48
communicates with the second diaphragm chamber 28. The branch part of the second negative pressure passage 48 is connected to an induction branch point 50.
shall be.

Next, the effect will be explained.

The first boost controller 18 has a normal advance characteristic and is operated by a predetermined intake system negative pressure depending on the load condition of the engine, that is, the opening degree of the carburetor throttle valve 4.

In the high load range, the carburetor throttle valve 4
Negative pressure is generated on the downstream side, and this negative pressure reaches the first diaphragm chamber 22 from the advance port 40 via the first negative pressure passage 38 . This negative pressure moves the first diaphragm 24 in the direction of arrow B against the first biasing means 26, and moves the rod 36 in the direction of arrow B, which is the advancing direction. As a result, the ignition timing is appropriately advanced in the high load range.

In addition, in a low load range, a large negative pressure in the intake pipe is generated, and this negative pressure in the intake pipe is transferred to the intake induction nozzle 46.
The pressure inside the intake guide passage 42 is reduced to negative pressure.
This negative pressure passes from the induction branch point 50 through the second negative pressure passage 48 to the second boost controller 2.
0 to the second diaphragm chamber 28. This negative pressure causes the second diaphragm 30 to move in the direction of arrow B against the second biasing means 32, and the rod 36 to move in the direction of arrow B, which is the advance direction.

In addition, as shown by the broken line in FIG. 2, the induction pressure _P1 , which is the negative pressure in the intake guide passage 42, is equal to the manifold pressure _P8 , which is the negative pressure in the intake passage 6, which is shown by the solid line.
It shows almost the same characteristics as .

Furthermore, in the low load range, especially during idling, which is substantially in the fully closed position, the induction pressure acts on the second diaphragm chamber, controlling the idling advance angle as shown by the broken line in FIG.
As the throttle opening shifts to the fully open direction, the manifold pressure acts on the first diaphragm chamber, and as shown by the solid line in Figure 3, the normal negative pressure advance control of the ignition timing by the manifold pressure is achieved, resulting in a low Ideal ignition timing characteristics can be obtained over the entire range from the load range to the high load range.

As a result, since the second boost controller 20 having the second diaphragm chamber 28 as a sub-diaphragm chamber is provided, it is possible to perform precise advance angle control especially in the low load range. Ideal ignition timing control can be achieved over the entire load range.

In addition, by providing the second negative pressure passage of the second boost controller in communication with the intake guide passage, there is no need to provide a new port near the carburetor throttle valve as in the conventional case, and the number of machining steps can be reduced. , the cost can be reduced.

Furthermore, if the manifold negative pressure is simply used for the second boost controller, it is necessary to increase the urging force of the second urging means of the second boost controller, and the urging force of the first urging means of the first boost controller increases. However, in the embodiment of this invention, the inlet of the intake guide passage is located above and below the carburetor throttle valve, so that the negative pressure from the inlet becomes the manifold negative pressure when fully closed. The biasing force of the second biasing means of the second boost controller can be weakened, and the adjustment of the first and second biasing means becomes easier, which is advantageous in practice.

Furthermore, since the intake guide passage negative pressure is taken out and utilized, it can also be used as a check signal to check whether the blowing pressure of the intake induction air is normal, and reliable operation of the intake guide passage can be ensured.

As is clear from the above description, this invention provides the following effects.

(1) The first negative pressure passage of the first boost controller is provided in communication with a predetermined position of the intake passage, and the second negative pressure passage of the second boost controller is provided in communication with the intake guide passage, which is different from conventional devices. The device of this invention successfully achieves ignition timing control, especially in the low load range, where ideal control could not be achieved, and as a result, the ignition timing control can be performed satisfactorily over the entire load range from low to high loads. Ideal ignition timing control becomes possible.

(2) Furthermore, since the negative pressure in the intake induction passage is taken out and used, it can also be used as a check signal for engine checking to determine whether the blowing pressure of the intake induction air is normal.

[Brief explanation of the drawing]

Figures 1 to 3 show examples of this invention, with Figure 1 being a system diagram of the ignition timing control system, Figure 2 being a graph of engine negative pressure and carburetor throttle valve opening, and Figure 3 being a diagram showing a graph of engine negative pressure and carburetor throttle valve opening. FIG. 3 is a diagram showing the relationship between throttle opening and ignition timing. In the figure, 4 is a carburetor throttle valve, 6 is an intake passage, 18 is a first boost controller, 20 is a second boost controller, 38 is a first negative pressure passage,
40 is an advance port, 42 is an intake guide passage,
48 is a second negative pressure passage, and 50 is an induction branch point.

Claims (1)

[Scope of utility model registration request] In an ignition timing control device for an internal combustion engine that has a vacuum advance device that retards the ignition timing in response to an increase or decrease in load, when the opening degree of the carburetor throttle valve is greater than a predetermined opening degree, the The first negative pressure passage of the first boost controller of the vacuum advance device is communicated with the intake passage located upstream from the carburetor throttle valve when the opening degree is less than a predetermined opening degree. The second negative pressure passage of the second boost controller of the vacuum advance device is provided midway through the intake guide passage which has an inlet at a location upstream of the valve and which opens and ends near the intake valve. Ignition timing control device for internal combustion engines.