JPH0324871Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an ignition timing control device for a spark ignition engine.

[Conventional technology]

A device is known that controls the ignition timing of a spark ignition engine in accordance with the load condition of the engine by introducing negative pressure generated in an intake pipe into a pressure chamber of a negative pressure advance mechanism of a distributor. Generally, the ignition timing is determined by MBT (Minimum Spark Advance for
It is preferable to control to the best torque. However, if the ignition timing is set to MBT, knocking will occur depending on the size of the engine load and the usage conditions of the engine. The occurrence of knotting has a negative effect on the engine. Therefore, conventional ignition timing control devices control the ignition timing to be retarded relative to the MBT to prevent knocking. Therefore, the ignition timing is always retarded from the MBT even when knocking does not occur, making it impossible to extract sufficient engine output.

In response, ignition timing control devices equipped with knock control systems have been developed. This sets the basic ignition timing to MBT, while
Detects knocking that occurs in the engine, retards the ignition timing when knocking is detected, and retards the ignition timing when knocking is detected, and when no knocking is detected, the MBT
It is an advancement towards. In this ignition timing control device, the ignition timing is not retarded unless knocking occurs, so that the engine can fully demonstrate its performance.

However, the knock control system requires a complicated ignition timing control circuit and is expensive. Therefore, in order to realize this at low cost, it has been proposed to use the negative pressure advance mechanism of the distributor also for controlling the ignition timing of the knock control system, thereby configuring the structure simply and at low cost. This is Japanese Patent Application Publication No. 54-163240 (Patent Application No. 163240)
-72756), in which negative pressure and atmospheric pressure are alternately introduced into the pressure chamber of the negative pressure advance mechanism, and the duty ratio at that time is controlled depending on whether or not knocking occurs.

[The problem that the idea attempts to solve]

However, in a device like this that uses a negative pressure advance mechanism as part of the knob control system,
There is a problem with poor control accuracy. In other words, in this device, the switching valve for alternately introducing negative pressure and atmospheric air is controlled by the duty ratio, but because the switching valve has poor responsiveness, the switching valve does not respond to changes in the duty ratio during duty ratio control. The switching operation cannot be followed and high precision control is not possible.

In view of such conventional problems, the purpose of the present invention is to improve the pressure chamber of the negative pressure advance mechanism.
By continuously introducing negative pressure at a relatively slow speed when no knocking occurs and atmospheric pressure when nokking occurs, ignition is performed with high precision according to the presence or absence of nodding, without being affected by the response of the switching valve. In addition to controlling the ignition timing, when the load shifts from high to low, the ignition timing is controlled to an advance angle that matches the low load without time delay.

[Means to solve the problem]

To achieve this objective, the present invention controls the ignition timing of a spark ignition engine according to the strength of the negative pressure introduced into the pressure chamber of the negative pressure advance mechanism of the distributor. In the ignition timing control device, a knocking detection device that detects knocking of the engine at a predetermined level or higher, a negative pressure supply source, and a first communication passage communicating between the pressure chamber and the negative pressure supply source and the pressure chamber are opened to the atmosphere. Disposed in a second communicating path that communicates with the mouth, when knocking is not detected by the knocking detection device, communicates with the first communicating path and blocks the second communicating path, and communicates with the second communicating path when knocking is detected. A switching valve is inserted in the first communication passage and the second communication passage to shut off the first communication passage, and is inserted in the first communication passage or the second communication passage to prevent negative pressure or large pressure from being applied to the pressure chamber when the first communication passage or the second communication passage is communicated. an orifice that slows down the introduction speed of air pressure; an advance port located upstream of the throttle valve during idling and downstream of the throttle valve when the throttle valve opens to a predetermined opening; A communication path that communicates with the pressure chamber,
The third communication path is arranged in parallel with the second communication path, and the check bubble is inserted into the third communication path and allows only negative pressure directed from the pressure chamber toward the advance port. It is characterized by

[Effect]

According to this configuration, while knocking does not occur, negative pressure is gradually introduced into the pressure chamber from the negative pressure supply source to advance the ignition timing, and when knocking occurs, atmospheric pressure is introduced into the pressure chamber. When the advance angle is reduced and the load shifts from high load to low load, negative pressure is quickly introduced into the pressure chamber.

[Effect of idea]

According to the present invention, as a result of slowing down the introduction speed of negative pressure or atmospheric pressure into the pressure chamber, the switching valve is only switched according to the presence or absence of knocking, and good responsiveness is not required. Regardless of the responsiveness of the switching valve, the ignition timing can be controlled with high precision, and when the load shifts from high to low, negative pressure is immediately introduced into the pressure chamber, so the load can be reduced without any time delay. The advance angle can be controlled to match the Moreover, compared to the conventional structure in which the ignition timing is controlled by duty ratio control, the structure can be extremely simplified.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of one embodiment. In the figure, 10 is an engine body, 20 is a distributor, and 85 is a carburetor. The distributor 20 is provided with a known negative pressure advance mechanism 30, and this negative pressure advance mechanism 30 has two pressure chambers,
It has a main chamber (pressure chamber) 31 and an auxiliary chamber 32. The advance angle during engine operation is controlled by negative pressure introduced into the main chamber 31, and the advance angle during idling operation is controlled in the auxiliary chamber 32, as will be described later. Note that FIG. 3 shows the advance characteristic of the negative pressure advance mechanism 30 due to the negative pressure introduced into the main chamber 31.

A knock sensor 41 is fixed to the engine body 10, particularly to the cylinder block. The knock sensor 41 is a known type and is adapted to extract vibrations caused by knocking as an electrical signal. The electrical signal taken out by the knock sensor 41 is, for example, as shown in FIG. 2A. The electrical signal taken out by the knock sensor 41 is input to a known knock judgment circuit 42.
Then, it is determined whether the electrical signal input from the knock sensor 41 is higher than a predetermined determination level, and if the electrical signal is higher than the determination level, it is determined that knocking is present, as shown in FIG. The final stage transistor 43 of the circuit 42 is turned off as shown in FIG. 2C. On the other hand, if the electric signal is smaller than the determination level, it is determined that knocking is not performed and the transistor 43 is turned on. Note that the knock judgment circuit 4
The determination level 2 is set so that the ignition timing is controlled to a point where weak knocking occurs that does not adversely affect the engine. These knock sensor 41 and knock determination circuit 42 constitute a knock detection device 40.

A port 51 is bored in the side wall of the carburetor 85, and this port 51 is connected to the throttle valve 84.
When it is fully closed, it is on the combustion chamber (not shown) side of the engine, that is, on the negative pressure side, and when the throttle valve 84 is opened to a predetermined opening, it is on the air cleaner (not shown) side, that is, on the atmospheric pressure side. It is in a position where The port 51 communicates with the auxiliary chamber 32 of the negative pressure advance mechanism 30 through a communication passage 87, and with the reservoir tank (negative pressure supply source) 53 through a communication passage 86 having a check valve 52 in the middle. has been done. Throttle valve 8 is connected to port 51.
4 is closer to the closed side than a predetermined opening degree, intake negative pressure is introduced, and the negative pressure is transferred to the subchamber 3 of the negative pressure advance mechanism 30.
2 and the reservoir tank 53. As a result, in the pre-chamber 32, the idle angle is controlled by the negative pressure during idling operation, and in the reservoir tank 53, the maximum value of the negative pressure introduced into the port 51 is controlled by the action of the check valve 52. store. Note that the maximum value of negative pressure means the lowest value in terms of absolute pressure. Hereinafter, in this specification, a large negative pressure means a low absolute pressure.

Further, like the port 51, an advance port 62 is bored in the side wall of the carburetor 85, and when the throttle valve 84 is in a fully closed state, the advance port 62 is on the atmospheric pressure side, and the throttle valve 84 is in a negative pressure side position when opened to a predetermined opening degree. Advance port 62 is
The communication passage 89 constituting the third communication passage and the communication passage 8 are arranged in parallel, and the main chamber 31 of the negative pressure advance mechanism 30 is is communicated with. Communication path 8
A check valve 83 is inserted in 9.
Only when the negative pressure in the advance port 62 becomes greater than that in the main chamber 31, the negative pressure is introduced from the advance port 62 into the main chamber 31 via the communication path 89. On the other hand, the communication passages 61, 88
A switching valve 71 and an orifice 92 are inserted in the switch valve 71, and when the switching valve 71 is connected between a and c, the negative pressure or atmospheric pressure generated at the advance port 62 is controlled by the action of the orifice 92. It is introduced into the main chamber 31 at a slow speed. As mentioned below,
Communication is established between a and c of the switching valve 71 mainly when the opening degree of the throttle valve 84 is quite large, and even if the advance port 62 is located on the negative pressure side at that time, the negative pressure is small and almost never large. Since the pressure is close to atmospheric pressure, in this case, the advance port 62 is used as an atmospheric opening in the present invention.

Furthermore, the reservoir tank 53 forming the negative pressure supply source is connected to the main chamber 3 of the negative pressure advance mechanism 30 by the communication passages 55 and 88 forming the first communication passage in the present invention.
1 is connected. An orifice 91, a volume 54, and a switching valve 7 are installed in the middle of the communication passages 55 and 88.
1 and orifice 92 are inserted, and when a and b of the switching valve 71 are in communication, the negative pressure stored in the reservoir tank 53 is slowly pumped into the main chamber by the action of the orifice 91. It was introduced in 31. Note that the orifice 91 has a larger air flow resistance than the orifice 92, so when the two orifices 91 and 92 are connected in series, only the orifice 91 acts as a flow resistance, and the orifice 92 acts as a flow resistance. Doesn't work. By the way, in the initial state where the switching valve 71 is connected between a and b, the main chamber 31 is connected to the orifice 91 as described below.
A predetermined amount of negative pressure stored in a volume 54 disposed on the side is introduced into the main chamber 31 at a relatively high speed. In this case, the capacity of the volume 54 is determined by the capacity of the main chamber 31, and the capacity of the reservoir tank 54 is determined by the capacity of the main chamber 31.
It is said to be about 1/10 to 1/20 of that of No. 3.

The switching valve 71 is operated to switch by excitation of the coil 72, and when the coil 72 is energized, communication is established between a and b, and when the coil 72 is not energized, communication is established between a and c. . And the coil 72
is the transistor 43 and the idle switch 8
2 to a power source 81. here,
The idle switch 82 is the throttle valve 84
This is a switch that is linked to the throttle valve 8.
4 is in the fully closed state, it is off, and in other cases it is on. Further, the power source 81 generates a predetermined voltage only when the engine is in operation, and is configured by, for example, a generator driven by the engine.

Next, the effect will be explained.

When the engine is started and is running at idle, the throttle valve 84 is fully closed as shown in FIG. 1, so intake negative pressure is introduced into the port 51, and the negative pressure It is introduced into the subchamber 32 of the mechanism 30. Therefore, the negative pressure advance mechanism 30 performs idle advance control. Also,
The negative pressure generated in the port 51 is removed by the check valve 5.
The negative pressure is also introduced into the reservoir tank 53 via 2, and the negative pressure is stored in the reservoir tank 53. At this time, since the idle switch 82 is turned off, the coil 72 is not energized, and therefore the switching valve 72 is not energized.
1, a and c are connected. However, since atmospheric pressure is introduced into the advance port 62, atmospheric pressure is introduced into the main chamber 31 of the negative pressure advance angle mechanism 30, and the advance angle control by the main chamber 31 is not performed.

Thereafter, when load operation of the engine is started and the throttle valve 84 is opened to a predetermined opening degree or more,
Since atmospheric pressure is introduced into the port 51, the subchamber 3
2, no negative pressure is introduced and idle advance is no longer performed. However, the atmospheric pressure generated at the port 51 is not introduced into the reservoir tank 53 due to the action of the check valve 52;
The check valve 5 is activated only when the negative pressure generated in the port 51 becomes greater than the stored negative pressure.
Negative pressure is introduced via 2. On the other hand, intake negative pressure corresponding to the load state of the engine is introduced into the advance port 62, and this negative pressure is first introduced into the main chamber 31 via the check valve 83, and the negative pressure advance mechanism 30 Then, the ignition timing is controlled to an advance angle according to the engine load condition. At this time, if knocking has not occurred in the engine, the transistor 43 is on, and the idle switch 82 is also on as the throttle valve 84 is opened, so the coil 72 is energized and the switching valve 71 communicates between a and b. Therefore, the large negative pressure stored in the reservoir tank 53 is gradually introduced into the main chamber 31 via the orifice 91, and the advance angle by the negative pressure advance mechanism 30 is further increased. By increasing the advance angle in this manner, engine output is increased and fuel efficiency is also improved.

However, as a result of increasing the advance angle, knocking becomes more likely to occur, and when the electrical signal picked up by the knock sensor 41 exceeds the determination level in the knock determination circuit 42, the transistor 43
is turned off. Therefore, the coil 72 is no longer energized, and the switching valve 71 is brought into communication between a and c. At this time, throttle valve 8
4 is large, the negative pressure introduced into the advance port 62 is small and close to atmospheric pressure, so the negative pressure introduced into the main chamber 31 is advanced through the orifice 92. It is reduced by a small negative pressure introduced from port 62.

Once the knocking subsides, turn on transistor 4 again.
3 is turned on, the coil 72 is energized, the switching valve 71 is switched, and communication is established between a and b.
3, a large negative pressure is introduced to gradually increase the advance angle.

By repeating these actions, the second
As shown in Figure D, the negative pressure in the main chamber 31 is adjusted. In other words, when there is no knocking, the negative pressure is increased at a relatively slow speed determined by the flow resistance of the orifice 91, and when there is knocking, the negative pressure is decreased at a relatively fast speed determined by the flow resistance of the orifice 92. be done. According to the magnitude of the negative pressure adjusted in this way, the advance angle is controlled as shown in FIG. Therefore, the advance angle is controlled near the knocking limit, and the engine output can be maximized within a range where knocking that adversely affects the engine does not occur. Moreover, the switching valve 71 is not a special one, and can be one that has been commonly used in the past.Furthermore, there is no need for duty ratio control, and it is only necessary to provide orifices 91 and 92, so the configuration is extremely simple. can do.

When there is a sudden transition from a relatively high-load operation in which the throttle valve 84 has a large opening to a relatively low-load operation in which the throttle valve 84 has a small opening, the negative pressure in the advance port 62 increases.
Knocking is likely to occur during high-load operation, so
The negative pressure in the main chamber 31 is adjusted to be relatively small.
Therefore, when the negative pressure in the advance port 62 becomes large, the negative pressure is introduced into the main chamber 31 via the check valve 83. Therefore, even when there is a sudden transition from a high load to a low load, the ignition timing can be controlled to an advance angle that matches the low load without time delay. That is, even if knocking no longer occurs due to the transition from high load to low load and the switching valve 71 is switched to communicate between a and b, the negative pressure in the reservoir tank 53 is not transferred to the main chamber 31. An orifice 9 is provided in the communication path 55, 88 to be introduced.
1 and 92 are inserted, the negative pressure advance mechanism 3
Although the advance angle due to zero is not immediately increased, the existence of the communication path 89 can prevent this delay from occurring. A check valve 83 is inserted in the communication passage 89, so that when operating in a relatively high load range without knocking, there is no large load in the main chamber 31 from the reservoir tank 53. When pressure is introduced and control is being performed to increase the advance angle, the advance port 62
A small negative pressure will have no effect.

If the vehicle is suddenly accelerated from idling,
The pressure in the advance port 62 only momentarily becomes negative when the throttle valve 84 passes through it, and then quickly returns to a value close to atmospheric pressure.
Almost no negative pressure is introduced into the main chamber 31 via the main chamber 9 . In addition, orifices 91 and 9 are also provided in the communication passages 55 and 88 that communicate the main chamber 31 with the reservoir tank 53.
2 exists, negative pressure is not immediately introduced into the main chamber 31, and the advance angle is not increased. However, in the embodiment, since the volume 54 is provided on the main chamber 31 side of the orifice 91, the a
-b is connected, the negative pressure stored in the volume 54 is transferred to the main chamber 3 through the orifice 92.
1, the orifice 91 with large flow resistance
The ignition advance angle can be advanced relatively quickly without being affected by this. Therefore, the engine output can be improved in accordance with acceleration driving, and acceleration driving performance can be improved. In this case, the speed at which negative pressure is introduced into the main chamber 31 can be changed depending on the capacity of the volume 54, and as shown in FIG. 4, if the volume 54 is increased, the idle switch 8
The speed at which negative pressure is introduced into the main chamber 31 from the start of acceleration when the switch 2 is turned from off to on becomes faster, and if the volume 54 is made smaller, the speed at which the negative pressure is introduced becomes slower. Therefore, by appropriately determining the capacity of the volume 54 with respect to the capacity of the main chamber 31, the ignition timing can be set so as to increase the engine output during acceleration operation within a range where knocking does not occur. If there is no volume 54 in Figure 4, the volume 5
Compared to the case where 4 is present, the rising speed of negative pressure is slower. This speed is determined by the flow resistance of the orifice 91. In FIG. 4, in the diagram showing the change in negative pressure when the volume 54 is provided, the part where the negative pressure momentarily drops, as indicated by the arrow, is caused by the diaphragm (not shown) in the main chamber 31. ) is caused by an overshoot.
In addition, in the diagram of FIG. 4, the portion surrounded by a broken line ◯ indicates that knocking has occurred in the engine and the negative pressure has been reduced.

Although a specific embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and includes various embodiments within the scope of the claims for utility model registration. Some of them are listed below.

A. The switching valve can also be constructed by combining two on-off valves.

(b) The atmosphere opening port through which the second communication passage communicates may not be an advance port, but may be a port provided with a dedicated air filter and opened to the atmosphere.

(c) The first communicating path and the second communicating path may be configured separately without having a part thereof shared.

The nitrogen holder 92 may be provided in the middle of the piping 61.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram of one embodiment of the present invention, Fig. 2 is a time chart explaining the operation of each part in one embodiment, and Fig. 3 is a progress chart of the negative pressure advance mechanism in one embodiment. The angle characteristic diagram, FIG. 4, is a line front diagram showing changes in the negative pressure in the pressure chamber of the negative pressure advance mechanism during acceleration. DESCRIPTION OF SYMBOLS 10... Engine main body, 20... Distributor, 30... Negative pressure advance mechanism, 31... Main chamber (pressure chamber), 32... Sub-chamber, 40... Knock detection device, 41... Knock sensor, 42...Knock determination circuit, 53...Reservoir tank (negative pressure supply source),
55, 88... Communication path (first communication path), 61, 8
8...Communication path (second communication path), 62...Advance port (atmospheric opening), 71...Switching valve, 91,
92... Orifice.

Claims (1)

[Claims for Utility Model Registration] Ignition timing control that controls the ignition timing of a spark ignition engine according to the strength of negative pressure introduced into the pressure chamber of a negative pressure advance mechanism of a distributor. The apparatus includes: a knocking detection device for detecting knocking of the engine at a predetermined level or higher; a negative pressure supply source; a first communication passage communicating the pressure chamber and the negative pressure supply source and communicating the pressure chamber with an atmosphere opening port; second to let
It is arranged in the communication path, and when knocking is not detected by the knocking detection device, the first communication path is communicated and the second communication path is cut off, and when knocking is detected, the second communication path is communicated and the first communication path is connected. a switching valve that shuts off; and a switching valve that is inserted between the first communication passage and the second communication passage to slow down the speed at which negative pressure or atmospheric pressure is introduced into the pressure chamber when the first communication passage or the second communication passage is communicated. an advance port located upstream of the throttle valve during idling and located downstream of the throttle valve when the throttle valve opens to a predetermined opening degree, and communicating the advance port and the pressure chamber. a third communication passage, which is a communication passage, and is arranged in parallel with the second communication passage; and a check bubble that is inserted into the third communication passage and allows only negative pressure directed from the pressure chamber toward the advance port. An ignition timing control device comprising: