JPS6221985B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition timing control device for an internal combustion engine having a so-called exhaust gas recirculation system that recirculates a portion of exhaust gas to an intake system in order to purify the exhaust gas.

In recent internal combustion engines, a portion of the exhaust gas is recirculated to the intake system in order to make the exhaust gas cleaner. When exhaust gas is recirculated to the intake system in this way, the combustion of the air-fuel mixture in the combustion chamber slows down, making it possible to reduce NOx, but on the other hand, the output of the engine decreases and drivability deteriorates.

Therefore, Japanese Utility Model Application Publication No. 55-60458 as a prior art discloses that, in an internal combustion engine equipped with an exhaust gas recirculation system, an advanced distributor located upstream from the upper closed position of the throttle valve is used for controlling the ignition timing of the internal combustion engine. A main vacuum advance mechanism associated with the port and a sub-vacuum advance mechanism associated with the throttle port located downstream from the bottom closed position of the throttle valve are provided. In the passageway connecting the corner mechanism,
When idling with the throttle valve fully closed, negative pressure at the throttle port is transmitted to the sub-vacuum advance mechanism, but when the throttle valve is opened from fully closed, negative pressure is transmitted from the throttle port to the sub-vacuum advance mechanism. A negative pressure switching valve is provided which cuts off transmission of the air and communicates the sub-vacuum advance mechanism with the atmosphere, and further transmits the negative pressure in the intake manifold to the sub-vacuum advance mechanism when exhaust gas is recirculated. By providing this, the ignition timing during idling can be adjusted.
While the sub-vacuum advance mechanism advances the ignition timing (so-called idling advance), when the exhaust gas recirculation is cut, the sub-vacuum advance mechanism is communicated with the atmosphere to advance the ignition timing to the main vacuum advance. Furthermore, during exhaust gas recirculation, the ignition timing is advanced by a sub-vacuum advance mechanism in addition to the main vacuum advance mechanism, compared to the ignition timing when exhaust gas recirculation is cut. I am proposing to do so.

However, this one changes the ignition timing as mentioned above,
Controlling the switching from the ignition timing during exhaust gas recirculation to the ignition timing when exhaust gas recirculation is cut, and vice versa, by communicating the sub-vacuum advance mechanism with the atmosphere or with the intake manifold. Therefore, when the intake manifold negative pressure transmitted to the sub-vacuum advance mechanism is switched to atmospheric pressure or vice versa,
The ignition timing will change suddenly, and the ignition timing should be smoothly shifted from the ignition timing that is compatible with exhaust gas recirculation to the ignition timing that is compatible with the exhaust gas recirculation cut, and vice versa. Therefore, there was a problem in that the output of the internal combustion engine fluctuated due to sudden changes in the ignition timing during each transition.

The present invention aims to solve this problem.

For this reason, the present invention provides a throttle valve in the intake system of an internal combustion engine equipped with an exhaust gas recirculation system, in which an advance port is provided upstream from the upper closed position and a throttle port is provided downstream from the lower closed position. On the other hand, the distributor in the engine includes a main vacuum advance mechanism that is connected to the advance port to obtain the required ignition timing during exhaust gas recirculation, and a main vacuum advance mechanism that is connected to the throttle port to adjust the ignition timing during idling. a sub-vacuum advance mechanism configured to obtain the required ignition timing at the time, a passage from the advance port to the main vacuum advance mechanism, and a passage from the throttle port to the sub-vacuum advance mechanism. are connected through a communication passage, and the communication passage includes a negative pressure switching valve that opens when the exhaust gas recirculation is cut by the exhaust gas recirculation system, and a sub-vacuum advance mechanism to the main vacuum advance mechanism. The structure includes a check valve that opens only in this direction.

With this configuration, during idling operation with the throttle valve closed, negative pressure is generated only in the throttle port, but even when the negative pressure switching valve in the communication passage is open, negative pressure is generated in the communication passage. The check valve is closed and the negative pressure at the throttle port is directly transmitted to the sub-vacuum advance mechanism, so when the engine is idling, the ignition timing is controlled only by the sub-vacuum advance mechanism. The idling angle is advanced.

Next, when the throttle valve is opened from fully closed, the negative pressure at the throttle port decreases toward atmospheric pressure, while a large negative pressure is generated at the advance port.

In this state, when the exhaust gas is not recirculated, the negative pressure switching valve and check valve in the communication passage are open, so the main vacuum advance mechanism and sub vacuum advance mechanism have no throttle ports. The average negative pressure of the negative pressure at the advanced port and the negative pressure at the advance port works, and the ignition timing is controlled by both the main vacuum advance mechanism and the sub vacuum advance mechanism without recirculating exhaust gas. In this state, when exhaust gas recirculation starts, the negative pressure switching valve in the communication passage closes, and the main vacuum advance mechanism is controlled by the large ignition timing at the advance port. Since the negative pressure is transmitted as is, the ignition timing during this exhaust gas recirculation is
The angle is controlled to be advanced even when the exhaust gas is not recirculated.

Then, when the exhaust gas recirculation is stopped (cut) due to the opening degree of the throttle valve being further increased, etc., the negative pressure switching valve in the communication passage opens, and the main vacuum advance mechanism and the sub The vacuum advance mechanism has negative pressure at the throttle port,
The average negative pressure with the negative pressure at the advance port acts, and the ignition timing is controlled to be retarded than the ignition timing during the recirculation of the exhaust gas.

In other words, the present invention applies a composite negative pressure of the negative pressure at the throttle port and the negative pressure at the advance port to the main vacuum advance mechanism and the sub vacuum advance mechanism when exhaust gas recirculation is cut. The ignition timing is controlled to the ignition timing that is suitable when exhaust gas recirculation is cut, while at the same time, when exhaust gas is recirculated, the negative pressure at the throttle port remains applied to the sub-vacuum advance mechanism. , by directly applying the negative pressure at the advance port to the main vacuum advance mechanism, the ignition timing is controlled to the ignition timing that is compatible with the recirculation of exhaust gas, which is different from the prior art described above. Since this is not a switching control that connects the sub-vacuum advance mechanism to the atmosphere or to the negative pressure of the intake manifold, it is possible to prevent sudden fluctuations in the ignition timing at the time of switching.

Therefore, according to the present invention, it is possible to control the ignition timing to suit each of idling, exhaust gas recirculation, and exhaust gas recirculation cut, but it is also possible to control the ignition timing to suit each of them. It is possible to smoothly shift from the ignition timing to the ignition timing that is compatible with the exhaust gas recirculation cut, and vice versa, and has the effect of reducing fluctuations in engine output due to the shift in ignition timing. have

Hereinafter, the present invention will be explained with reference to drawings of embodiments. In the drawings, reference numeral 1 indicates an internal combustion engine, and an exhaust port 2 in this engine is connected to an exhaust passage 3 for exhaust gas from a converter using an oxidation catalyst or a three-way catalyst, etc. A gas purification device 4 is connected, and a carburetor 7 as a fuel supply means is connected to the intake port 5 of the engine 1 via an intake manifold 6, and an air cleaner 8 is provided upstream of the carburetor 7. The carburetor 7 is equipped with a throttle valve 9 for adjusting the intake mixture.

Reference numeral 10 indicates a distributor for the engine 1, and the distributor 10 is equipped with a centrifugal advance mechanism (not shown) that controls the advance of the ignition timing in proportion to the engine speed, and The breaker plate 12 equipped with the breaker arm 11 has a sub-vacuum advance mechanism 13 and a main vacuum advance mechanism 14 that advance the ignition timing by rotating the breaker plate 12 in the direction of arrow A. are connected via a connecting rod 15. The double advance mechanism 1
3 and 14 are configured such that a sub diaphragm case 18 and a main diaphragm case 19 each having diaphragms 16 and 17 are directly connected via a partition plate 20, and the main diaphragm case 1
The diaphragm 17 in the main diaphragm chamber 24 is provided with a connecting piece 22 that is pressed against the partition plate 20 by the main spring 21 in the main diaphragm chamber 24, and connects the connecting rod 15 from the breaker plate 12 into the sub-diaphragm case 18. At the same time, the diaphragm 16 and the connecting piece are inserted into the connecting piece 22 through the sub-diaphragm chamber 23, and a collar 25 is provided at the insertion end to engage with the connecting piece 20. A secondary spring 26 is provided between the flange 25 and the inner part of the connecting piece 22 to provide a gap of an appropriate distance S ₁ in the advancing direction of the connecting rod 15. A stopper piece 27 is placed at an appropriate distance _S2 between the back of the diaphragm 17.
will be established. The sub-diaphragm chamber 23 is connected via a passage 28 to a throttle port 29 provided at a location slightly downstream of the lower closed position of the throttle valve 9 when the throttle valve 9 is in a fully closed state (idle opening degree). The diaphragm chamber 24 is connected to the passage 30
When the throttle valve is in a fully closed state, it is connected to an advance port 31 provided at a portion slightly upstream of the upper closed position of the throttle valve through the throttle port 29.
The first interval is set by the sub-advance mechanism 13 using the negative pressure of
The advance angle is controlled between S ₁ , and in the load range where the negative pressure of the advance port 31 becomes large, the advance port 31
The main advance angle mechanism 14 related to the negative pressure controls the advance angle during the second interval _S2 ,
In this case, the advance angle value in the advance angle control by the main advance angle mechanism is a value that is close to the optimal ignition timing (MBT) at that time (required ignition timing) to the extent that knocking does not occur during exhaust gas recirculation to the intake system. Further, the advance value by the sub-advance mechanism is set so as to be the required ignition timing in a load range where the negative pressure of the throttle port 29 is high.

Reference numeral 32 denotes a diaphragm type exhaust gas recirculation control valve, the inlet of which is connected to the exhaust passage 3 through a recirculation passage 34 with an orifice 33, and the outlet connected to the intake manifold 6 through a recirculation passage 35. The valve body 36 of the reflux control valve 32 is biased in the normally closed direction by a spring 38 within the diaphragm chamber 37. 39 is the exhaust pressure regulating valve,
A diaphragm 42 is provided which separates an atmospheric communication chamber 40 and an exhaust pressure chamber 41. The communication pipe 46 is opened and closed by a flap 45, and the communication pipe 46 is opened and closed by a spring 47.
The exhaust pressure chamber 41 is connected between the valve body 36 of the control valve 32 in the reflux passage 34 and the orifice 33 via a passage 48, and the communication pipe 46 is connected to the passage 49 to the diaphragm chamber 37 of the reflux control valve 32, and
Via the negative pressure outlet passage 51 with orifice 50,
Provided at approximately the same position as the advance port 31
It is connected to the EGR port 52. Reference numeral 53 indicates a reflux control means, and the reflux control means 53 includes a diaphragm 57 equipped with a valve body 56 that opens and closes a port 55 in the valve chamber 54 , and a diaphragm chamber 58 .
A spring 59 is provided inside the valve body 56 to normally close the port 55, and the port 55 is connected to the passage 49 which connects the exhaust pressure regulating valve 39 and the reflux control valve 32 via the passage 60, and the valve chamber 54 is connected to the passage 49. The diaphragm chamber 58 is connected to an atmospheric communication point such as the clean side of the air cleaner 8 through a passage 61, and the diaphragm chamber 58 is connected to the passage 30 to the main advance mechanism 14 through a passage 62.
A delay mechanism 65 having an orifice 63 and a check valve 64 in parallel is provided in the passage 30 to the main advance mechanism 14.
is provided.

66 indicates a negative pressure switching valve, and the negative pressure switching valve 66
is a valve body 68 that opens and closes the port 69 in the valve chamber 67
is provided in a diaphragm 72 which is divided into two chambers 70 and 71, while a spring 73 is provided in one diaphragm chamber 70 to bias the valve body 68 in the normally open direction, and the port 69 is connected to the main valve through a communication passage 74. Corner mechanism 1
4, the valve chamber 67 is connected to the passage 28 to the sub-advance mechanism 13 via a communication passage 75, and one diaphragm chamber 70 is connected to the passage 6 through a passage 76.
0, the other diaphragm chamber 71 is connected to the atmospheric passage 44 via the passage 77, and the valve chamber 6
The passage 2 is connected to the communication passage 75 connecting the passage 28 and the passage 28.
A check valve 78 is provided which opens in the direction from 8 to the valve chamber 67.

In this configuration, the negative pressure at the 29 throttle ports is highest when the throttle valve 9 is closed, and gradually decreases as the throttle valve is opened.
Negative pressure at 52 EGR ports is controlled by throttle valve 9
When the throttle valve 9 is closed, it is approximately atmospheric pressure, and as the throttle valve is opened, the pressure gradually increases, and when the throttle valve 9 is open from the closed position to the advance port 31, the pressure is idling or in the low load/low rotation range. In this case, since both the advance port 31 and the EGR port 52 have approximately atmospheric pressure, the recirculation control valve 32 does not operate, and therefore the exhaust gas is not recirculated, and no negative pressure is applied to the main advance angle mechanism 14. First, the main advance mechanism 14 does not advance the ignition timing, but since the negative pressure of the throttle port 29 acts on the sub advance mechanism 13, it is not possible to advance the ignition timing when the engine is idling or in the low load/low rotation range. The ignition timing can be controlled by the sub-advance mechanism 13 to the required ignition timing in the idling and low load/low rotation ranges.

Next, move the throttle valve 9 to the advance port 31.
When accelerating with the opening beyond the position, the negative pressure in the advance port 31 and the EGR port 52 increases, the negative pressure in the EGR port 52 is transmitted to the atmosphere communication chamber 40 of the exhaust pressure regulating valve 39, and the exhaust pressure becomes high. Then, the diaphragm 42 closes the atmosphere communication pipe 46, and the negative pressure in the atmosphere communication chamber 40 acts on the diaphragm chamber 37 of the recirculation control valve 32 through the passage 49, so the valve body 36 opens and exhaust gas flows into the intake system. is refluxed to.

During the recirculation of this exhaust gas, the negative pressure switching valve 66
The passage 4 is connected to one diaphragm chamber 70 in the
9 acts, the valve body 68 closes the port 69 and blocks the communication passages 74 and 75 between the passage 30 to the main advance mechanism 14 and the passage 28 to the sub-advance mechanism 13, Since the negative pressure of the advance port 31 acts on the main advance mechanism 14 through the passage 30, the main advance mechanism 14 adjusts the ignition timing according to the negative pressure of the advance port 31 to the required ignition timing at the time of exhaust gas recirculation. control. After the time set by the delay mechanism 65 has elapsed from this point, the engine rotates at a substantially constant speed, and when the negative pressure acting on the diaphragm chamber 58 of the reflux control means 53 increases until it overcomes the spring 59, the valve body 56 opens. port 55
By opening the reflux control valve 32, the atmosphere is introduced into the diaphragm chamber 37 of the reflux control valve 32, and the valve element 36 is closed, thereby cutting off the reflux of exhaust gas. At the same time, one diaphragm chamber 70 in the negative pressure switching valve 66 becomes atmospheric pressure, and its valve body 68 opens the port 69, which opens the passage 30 to the main advance mechanism 14 and the passage 28 to the sub advance mechanism 13. Communication passage 7 with
4,75 are connected. At this time, the negative pressure in the passage 30 to the main advance mechanism 14 is greater than the negative pressure in the passage 28 to the sub advance mechanism 13. The air in the passage 28 is introduced via the communication passages 75, 74 and the check valve 78, and the negative pressure in the passage 30 to the main advance mechanism 14 is equal to the negative pressure in the advance port 31 and the throttle port 29. The negative pressure decreases to the average negative pressure value, and the negative pressure decreased to this average negative pressure value acts on the main advance mechanism 14, so the ignition timing at the time of exhaust gas recirculation cut is set according to the exhaust gas recirculation. The ignition timing is retarded from the ignition timing when the exhaust gas is not being recirculated.

In a high load range when the throttle valve 9 is fully opened or almost fully opened, the negative pressure in the advance port 31 and the EGR port 52 is small, so the recirculation control valve 32 does not operate and does not recirculate exhaust gas. The average negative pressure (approximately atmospheric pressure) of the negative pressure in the advance port 31 and the negative pressure in the throttle port 29 acts on the main advance mechanism 14 to adjust the ignition timing to the required ignition when exhaust gas is not recirculated. It is controlled based on the timing.

Note that the exhaust gas recirculation system is not limited to the one in the above embodiment, but may also be an exhaust gas recirculation system that recirculates exhaust gas during acceleration and partial load, and cuts or reduces exhaust gas recirculation in other operating ranges. It goes without saying that the invention can be similarly applied to gas reflux systems. It goes without saying that the present invention is applicable not only to carburetor internal combustion engines but also to fuel injection internal combustion engines (in this case, the throttle valve of the carburetor in the embodiment shown in FIG. (You can replace it with a valve).

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of the vacuum advance angle mechanism in FIG. 1. 1... Internal combustion engine, 3... Exhaust passage, 4... Exhaust gas purification device, 6... Intake manifold, 7... Carburetor, 8
...Air cleaner, 9...Throttle valve, 34, 35
...Exhaust gas recirculation passage, 32...Recirculation control valve, 39...
Exhaust pressure adjustment valve, 31...Advance port, 29...Throttle port, 52...EGR port, 10...Distributor, 14...Main vacuum advance mechanism, 13...Sub vacuum advance mechanism, 74, 75...Communication Passage, 66... Negative pressure switching valve, 78... Check valve.

Claims (1)

[Claims] 1. With respect to a throttle valve in the intake system of an internal combustion engine equipped with an exhaust gas recirculation system, an advance port is provided upstream from the upper closed position and a throttle port is provided downstream from the lower closed position. In the distributor,
A main vacuum advance mechanism that relates to the advance port to obtain the required ignition timing during exhaust gas recirculation, and a sub-advanced mechanism that relates to the throttle port to obtain the required ignition timing during idling operation. a vacuum advance mechanism, the passage from the advance port to the main vacuum advance mechanism and the passage from the throttle port to the sub vacuum advance mechanism are connected via a communication passage; The passage includes a negative pressure switching valve that opens when the exhaust gas recirculation system cuts the exhaust gas recirculation, and a check valve that opens only in the direction from the sub-vacuum advance mechanism to the main vacuum advance mechanism. An ignition timing control device for an internal combustion engine, comprising: