JPH057508Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a device for controlling the ignition timing of an internal combustion engine of an automobile or the like.

[Background of the idea]

For an internal combustion engine, in order to extract the explosion of the air-fuel mixture in the cylinder most efficiently as output of the internal combustion engine, it is desirable that the maximum pressure caused by the explosion be located at a position slightly later than top dead center. On the other hand, it takes a certain amount of time after the compressed air-fuel mixture in the cylinder is ignited until the maximum pressure is reached. This time varies depending on factors such as the internal combustion engine compression ratio, the type of fuel, the air-fuel ratio, and the load condition of the internal combustion engine. Therefore, it is desirable to control the ignition timing to be optimal according to the fluctuations in the above factors.

[Conventional technology]

Conventionally, such ignition timing control has been based on a method in which the optimum ignition timing for the internal combustion engine is stored in advance in a microcomputer, and the optimum ignition advance angle is obtained based on signals from each sensor.

[Problem that the invention attempts to solve]

However, the above-mentioned conventional method has the problem that the electronic components required therefor are expensive and that analog control is not possible.

[Means for solving problems]

The present invention, as a means to solve the above-mentioned conventional problems, connects a negative pressure introduction path 5 from a carburetor 3 to a negative pressure advance device 2, and connects an air flow to the negative pressure introduction path 5. A one-way valve that allows the flow to flow only from the device 2 to the carburetor 3 side and a delay valve that allows the negative pressure of the carburetor 3 to be transmitted to the negative pressure advance device 2 with a delay are provided in parallel, and a is provided with a bypass passage 7 that bypasses the one-way valve and the delay valve and is provided with an on-off valve 8, the on-off valve 8 is controlled by the intake pipe negative pressure, and when the intake pipe negative pressure is greater than a predetermined pressure, the on-off valve 8 is opened and closed. An ignition timing control device for an internal combustion engine is provided in which a valve 8 is closed and the on-off valve 8 is set to open when the pressure is lower than a predetermined pressure.

[Function] In the above configuration, when the internal combustion engine transitions from steady running with large intake pipe negative pressure to accelerated running with small intake pipe negative pressure, when the throttle valve opening of the carburetor is small, the intake pipe negative pressure is reduced to the predetermined pressure. becomes larger and the on-off valve closes. In this state, the negative pressure on the negative pressure advance device side is higher than that on the carburetor side, and air flows from the carburetor side to the negative pressure advance device via the negative pressure introduction path, while on the valve side, the air flow is It is shut off and air flows only through the delay valve. Therefore, the decrease in the negative pressure within the negative pressure advance device is delayed and the ignition timing can be advanced beyond the set ignition timing. On the other hand, when the throttle valve opening degree of the carburetor is small, the intake pipe negative pressure becomes lower than the predetermined pressure and the on-off valve opens. In this state, air flows through the bypass path, so negative pressure fluctuations within the carburetor are transmitted to the negative pressure advance device without delay.

[Effect of idea]

Therefore, in the present invention, when the internal combustion engine transitions from steady running to accelerated running and the throttle valve opening of the carburetor is small, the ignition timing is advanced to the knocking limit to improve output and, in turn, improve drivability. When the throttle valve opening of the carburetor is large, normal advance characteristics are ensured in accordance with negative pressure fluctuations within the carburetor, and problems such as knocking are eliminated. The device of the present invention does not require any electronic components and is inexpensive.

〔Example〕

FIG. 1 shows an embodiment of the present invention. In the figure, 1 is a power distributor, 2 is a negative pressure advance device attached to the power distributor 1, and the negative pressure advance device 2 includes a case 21 and an inner chamber 21A inside the case 21.
and an outer chamber 21B.
It consists of a spring 23 that urges the diaphragm 22 in the outer chamber 21B toward the inner chamber 21A.
Reference numeral 3 designates a vaporizer, in which a flow path 31 is formed with a ventilator portion 31A, a nozzle 32 is opened in the ventilator portion 31A of the flow path 31, and a choke valve 33 is provided on the upstream side of the ventilator portion 31A. , a throttle valve 34 is provided on the downstream side.
The lower end of the carburetor 3 is connected to an intake pipe 4 of an internal combustion engine (not shown).

The carburetor 3 and the negative pressure advance device 2 are connected by a negative pressure introduction passage 5, and the carburetor 3 side of the negative pressure introduction passage 5 is connected to the throttle valve 34 when the throttle valve 34 is closed forward. It is located upstream and opens at a position downstream of the throttle valve 34 when the throttle valve 34 is open, and the negative pressure advance device 2 side opens into the outer chamber 21B.

A one-way delay valve 6 is interposed in the negative pressure introduction path 5. The one-way delay valve 6 is provided with a passage hole 61 and a small diameter orifice 62 in parallel.
1 has a one-way valve 63 interposed therein. Further, the negative pressure introduction path 5 is provided with a bypass path 7 that bypasses the one-way delay valve 6, and an electromagnetic on-off valve 8 is interposed in the bypass path 7. The electromagnetic on-off valve 8 includes a valve body 81 that opens and closes the bypass passage 7, a spring 82 that biases the valve body 81 in the closing direction, and an electromagnetic coil 83 that operates the valve body 81 in the opening direction.
9 is a negative pressure switch, which includes a case 91, a diaphragm 92 that divides the inside of the case 91 into an inner chamber 91A and an outer chamber 91B, and a spring 93 that biases the diaphragm 92 toward the inner chamber 91A in the outer chamber 91B. and a contact 94 provided in the inner chamber 91A, a contact plate 92A is provided in the center of the diaphragm 92 to abut the contact 94, one end of the contact 94 is connected to a power source 95, The other end of the contact 94 is connected to the electromagnetic coil 83 of the electromagnetic on-off valve 8 . Reference numeral 101 denotes a negative pressure introduction path that communicates the intake pipe 4 with the outer chamber 91B side of the case 91 of the negative pressure switch 9.

In the above configuration, when the internal combustion engine transitions from steady running with a large negative pressure in the intake pipe 4 to accelerated running with a small negative pressure in the intake pipe 4, when the opening degree of the throttle valve 34 of the carburetor 3 is small, the negative pressure is Since the negative pressure taken out to the pressure introduction path 101 becomes higher than the set pressure of the negative pressure switch 9, the diaphragm 92 moves toward the outer chamber 91B against the spring 93 of the negative pressure switch 9, and Since the contact 94 is in the OFF state, the electromagnetic coil 83 of the electromagnetic on-off valve 8 is not energized, and the valve body 81 closes the bypass path 7 by the spring 82. In this state, the negative pressure inside the carburetor 3 taken out from the negative pressure introduction path 5 becomes smaller than the negative pressure on the negative pressure advance device 2 side. Negative pressure advance device 2 from the carburetor 3 side
Flows to the side. However, in the one-way delay valve 6, the one-way valve 63 blocks the flow of air through the passage hole 61, and the air flows only through the small-diameter orifice 62. However, the flow path resistance of the small diameter orifice 62 limits the amount of air flowing from the carburetor 3 side to the negative pressure advance device 2 side, and the negative pressure on the negative pressure advance device 2 side becomes negative pressure on the carburetor 3 side. There is a delay before the corresponding pressure is reached. This delay is adjusted by the diameter of the small diameter orifice 62.

Next, when the internal combustion engine shifts from steady running with a large negative pressure in the intake pipe 4 to accelerated running with a small negative pressure in the intake pipe 4, when the opening degree of the throttle valve 34 of the carburetor 3 is large, negative pressure is introduced from the intake pipe 4. Since the negative pressure taken out to the passage 101 becomes smaller than the set pressure of the negative pressure switch 9, the diaphragm 92 is moved to the inner chamber 91A by the spring 93 of the negative pressure switch 9, and the contact 94 is turned ON.
In this state, the electromagnetic coil 83 of the electromagnetic on-off valve 8 is energized, and the valve body 81 opens the bypass passage 7 against the force of the spring 82. In this state, the negative pressure taken out from the carburetor 3 to the negative pressure introduction path 5 is directly guided to the outer chamber 21B of the negative pressure advance device 2, and the negative pressure advance device is activated according to the change in the negative pressure. 2 is activated to control the advance angle.

Applying the operation of the ignition timing control device of the present invention to the operating pattern of an internal combustion engine, when transitioning from steady driving to accelerated driving, during slow acceleration with a small throttle valve opening, the negative pressure advance device is activated for a predetermined period of time. 2 is delayed to maintain the ignition timing advanced from the set ignition timing to improve drivability. In addition, during sudden acceleration with a large throttle valve opening, the negative pressure advance device 2 operates in response to changes in the negative pressure taken out from the carburetor 3 to the negative pressure introduction path 5 to maintain the ignition timing as set. Problems such as locking can be resolved.

Figure 2 is a graph with advance angle (crank angle) on the vertical axis and intake pipe negative pressure on the horizontal axis. Indicates the allowance. In the figure, the solid line is the advance angle set with respect to the change in intake pipe negative pressure. Figure 2 shows that as the intake pipe negative pressure goes from small to large, the knocking limit expands toward the advance side, and in that case, the advance margin increases by the shaded area with respect to the normal set ignition timing. Therefore, the operation of the negative pressure advance device 2 is delayed and the ignition timing is set near the outer edge of this region.

Figure 3 shows the relationship between advance angle and intake pipe negative pressure during slow acceleration.In the conventional case, the throttle valve was opened at point A and the intake pipe negative pressure went from high to low, as shown by the solid line. However, in the case of the present invention, the ignition timing is delayed gradually as shown by the dotted line, which improves driveability.

Figure 4 shows the relationship between advance angle and intake pipe negative pressure during sudden acceleration. When the throttle valve is opened at point A and the intake pipe negative pressure goes from high to low, the ignition timing immediately follows. and changes to the set value.

In addition to the negative pressure introduction path 5 that takes out negative pressure from the carburetor 3, the negative pressure introduction path that takes out negative pressure from the intake pipe 4 is connected to the negative pressure advance device 2, and the negative pressure is advanced even during idling. By operating the angle device 2 to advance the ignition timing, it is possible to improve fuel efficiency during idling. Further, an electronic negative pressure detection means may be used instead of the diaphragm type negative pressure switch 9, but a mechanical negative pressure detection means such as a diaphragm type is less expensive. Furthermore, as a delay means, a microcomputer, a timer, etc. may be used in place of the small-diameter orifice 62, but it goes without saying that the cost is reduced by using the small-diameter orifice 62 rather than such electronic means. .

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of an embodiment of the present invention, Fig. 2 is a graph showing the relationship between advance angle and intake pipe negative pressure, and Fig. 3 is a graph showing changes in intake pipe negative pressure and ignition timing during slow acceleration. FIG. 4 is a graph showing changes in intake pipe negative pressure and changes in ignition timing during rapid acceleration. In the figure, 2... negative pressure advance device, 3... carburetor, 4
... Intake pipe, 5 ... Negative pressure introduction path, 6 ... One-way delay valve, 7 ... Bypass path, 8 ... Solenoid on-off valve, 9
...Negative pressure switch, 101...Negative pressure introduction path.

Claims (1)

[Scope of utility model registration request] A negative pressure introduction path from the carburetor is connected to the negative pressure advance device, and the negative pressure introduction path includes a one-way valve that allows air flow to flow only from the negative pressure advance device to the carburetor side, and a negative pressure of the carburetor. A delay valve that transmits the negative pressure to the negative pressure advance device with a delay is provided in parallel, and the negative pressure introduction path is further provided with a bypass path in which the one-way valve and the delay valve are bypassed and an on-off valve is provided. The valve is controlled by intake pipe negative pressure, and is set so that when the intake pipe negative pressure is greater than a predetermined pressure, the on-off valve closes, and when it is less than the predetermined pressure, the on-off valve opens. Ignition timing control device for internal combustion engines.