JPS5913343Y2 - Vehicle internal combustion engine - Google Patents

Description

[Detailed description of the invention] This invention enables the operation of the exhaust gas recirculation device, power distribution device, and mixture enrichment device to be adjusted simultaneously in order to efficiently reduce harmful components in exhaust gas and to stabilize the engine at the same time. This invention relates to a vehicle internal combustion engine.

In order to reduce the concentration of NoxtC contained in the exhaust gas of a vehicle internal combustion engine, it is known that it is effective to provide an exhaust gas recirculation device that recirculates a portion of the exhaust gas into intake air.

However, as mentioned above, exhaust gas recirculation reduces engine output, so in order to maintain running characteristics at high speeds where high output is required, engine performance, that is, stable running, is needed rather than exhaust countermeasures. Because of the need to place emphasis on this, it is effective to reduce or stop exhaust gas recirculation, improve combustion efficiency, and increase fuel efficiency.

On the other hand, if the ignition timing is advanced at the same time as exhaust gas recirculation, the knocking zone will shift at high speeds as exhaust gas recirculation decreases or stops, and knocking is likely to occur, resulting in extremely low output. In addition to deteriorating drivability due to a decrease in fuel consumption, there are also drawbacks such as deterioration of emissions, overheating of the catalytic converter, etc., and deterioration of durability.

Therefore, it is desirable to retard the ignition timing at the same time as the exhaust gas recirculation is reduced or stopped.

In addition, when performing exhaust gas recirculation, it is recommended to set the air-fuel ratio of the mixture to be richer than the stoichiometric air-fuel ratio to eliminate problems such as poor ignition, reduced output, and poor starting performance caused by exhaust gas recirculation. desirable.

From this point of view, conventional devices such as JP-A-53-178
Looking at No. 03, this engine advances the ignition angle even though exhaust gas recirculation is not performed in the low vehicle speed range and small opening range of the throttle valve provided in the intake passage, resulting in lower output and worse fuel efficiency. This was inconvenient.

In view of these circumstances, the present invention reduces or stops exhaust gas recirculation when the vehicle speed is in a high speed range to increase combustion efficiency.
Moreover, in synchronization with the reduction or stop of this exhaust recirculation, the ignition timing advance is delayed to the optimum state to prevent knocking, efficiently reducing harmful components of the exhaust without sacrificing output or heat load, and other than the above. The purpose of the present invention is to provide an exhaust countermeasure device having an extremely simple configuration that improves ignition performance, output, and startability by enriching the air-fuel mixture in the low vehicle speed region of the vehicle.

Hereinafter, the present invention will be described in detail based on an embodiment shown in the accompanying drawings.

In the figure, an exhaust gas recirculation passage 2 branched from an exhaust passage of an engine (not shown) is connected to an intake passage 1 downstream of a carburetor throttle valve 6 of an internal combustion engine mounted on a vehicle.

A valve body 3 provided in the exhaust gas recirculation passage 2 is connected to a diaphragm 5 of a negative pressure responsive exhaust recirculation control valve 4, and when a negative pressure working chamber 7 defined by the diaphragm 5 and a throttle valve 6 are fully closed, It opens to the intake passage 1 located slightly upstream of the throttle valve 6 and downstream of the throttle valve 6 as the valve opening increases.
1 and a first negative pressure take-out port (8a) via a first negative pressure signal passage 8.

The negative pressure signal of the first negative pressure signal passage 8 is diluted and adjusted with the atmosphere by the valve element 9a of the negative pressure regulating valve 9.

That is, the negative pressure regulating valve 9 connects the venturi negative pressure signal passage 10 taken out from the venturi portion of the carburetor intake passage 1 to the negative pressure working chamber 11, and connects the exhaust recirculation control valve 4 of the exhaust gas recirculation passage 2 to the negative pressure working chamber 11.
Engine exhaust pressure signal passage 13 branched from the upstream part of
are connected to a pressure working chamber 14, and these working chambers 11.
Diaphragms 12 and 15 defining rod 14
are interconnected through.

The valve body 9a is then moved up and down by moving the diaphragm 12.15 up and down based on the venturi negative pressure in the intake passage 1 (a function of the amount of intake air) and the pressure in the exhaust gas recirculation passage 2 (a function of the amount of intake air, load, etc.). move the first negative pressure signal path 8
As the air opening port 8b of the engine is opened and closed, as the intake air amount calculated from the venturi negative pressure increases, and as the intake air amount and load calculated from the engine exhaust pressure increase, the intake negative pressure signal increases. Ratio of passage 8 open to atmosphere (
The amount of exhaust gas recirculation is increased by decreasing the atmospheric dilution ratio of the suction negative pressure and increasing the opening degree of the exhaust gas recirculation control valve 3.

On the other hand, a second negative pressure outlet port 19 is located upstream near the throttle valve 6 when the valve is fully closed and becomes downstream of the throttle valve as the valve opening increases, and a second negative pressure inlet port 20 is located downstream of the throttle valve 6 at all times. The negative pressure signal passage 21 of the negative pressure signal passage 21 is connected to the negative pressure working chamber 22a of a conventionally known negative pressure advance device 22.

As a result, as the combined negative pressure introduced from the second negative pressure outlet port 19 and the negative pressure inlet 20 increases, the ignition timing is gradually advanced as the engine load increases.

23 is a distributor.

In the figure, first and second negative pressure extraction ports 8a,
19 is arranged shifted in the upstream and downstream directions of the intake air,
For convenience of illustration, this is actually opened at a position where the throttle valve 6 is opened and closed synchronously with the same opening degree.

Furthermore, the negative pressure inlet 20 is provided to create a stable composite negative pressure between the second negative pressure outlet port 19; This type of negative pressure extraction means has been known in the past, and there is no problem even if the negative pressure is extracted only from.

The second negative pressure signal passage 21 is opened to the atmosphere via a normally closed first electromagnetic on-off valve 24.

Further, the second negative pressure signal path 21 and the first negative pressure signal path 8 allow atmospheric air to flow only from the second negative pressure signal path 21 toward the first negative pressure signal path 8. Communication is established via the check valve 25.

Therefore, when the check valve 25 is in communication, the first negative pressure signal passage 8 is also opened to the atmosphere via the second negative pressure signal passage 21 and the electromagnetic on-off valve 24.

Specifically, the check valve 25 connects the communication hole 25 b of the partition wall 25 a of both chambers A and B to the valve body 25 d by the spring force of the spring 25 C from the B chamber side which communicates with the first negative pressure signal passage 8.
The structure is such that it is seated and closed.

For this reason, a pressure difference between chambers A and B occurs in the valve body 25 d.
Only when the pressure on the chamber side becomes low, the valve body 25d opens to create an air flow from the A chamber to the B chamber, which acts as a check to close the chamber.

Solenoid 26 and power supply 2 that control opening and closing of electromagnetic on-off valve 24
7, a switch 28 is connected which detects that the vehicle is running at a high speed of at least a predetermined value (for example, at least 55 km/h) and closes a contact at the time of this detection.

If it is detected that the vehicle speed is above a predetermined value, the switch 28 is closed, the solenoid 26 is energized, the electromagnetic on-off valve 24 is opened, the second negative pressure signal passage 21 is opened to the atmosphere, and the negative pressure is advanced. The signal negative pressure supplied to device 22 is diluted with atmospheric air.

At this time, in the check valve 25, the pressure in chamber A becomes atmospheric pressure, and a pressure difference is generated between chamber A and chamber B, which has a large negative pressure, and opens the valve body 25d.

As a result, the atmosphere flows into the second negative pressure signal path 21 via the check valve 25, and the signal negative pressure in the first negative pressure signal path 8 is also diluted with the atmosphere.

The switch 28 may be any switch that operates upon detecting a high vehicle speed of a predetermined value or higher, and may be a vehicle speed switch that directly responds to the vehicle speed, a rotational speed switch that determines the vehicle speed from the engine rotational speed, or Any vehicle speed detection means can be employed, such as a transmission switch that measures the vehicle speed based on the gear change state of the vehicle's transmission.

In the exhaust control device having such a configuration, the vehicle can reach a predetermined value (5
When the vehicle is traveling at a low speed (less than 5 km/h), the contact of the switch 28 is open, so the solenoid 26 is kept in a demagnetized state, and the electromagnetic on-off valve 24 is kept closed.

Therefore, the atmosphere is not introduced into the second negative pressure signal passage 21, and the wind pressure of the negative pressure advance device 22 is maintained while the negative pressure taken out from the first negative pressure take-out port 19 and the negative pressure inlet 20 remains as it is. The distributor 23 is supplied to the working chamber 22a.
The base plate (not shown) is rotated to advance the vacuum advance angle, while the atmospheric pressure in the first negative pressure signal passage 8 is increased in response to the venturi negative pressure derived from the venturi section and the exhaust pressure taken out from the exhaust gas recirculation passage 2. Controls the opening and closing of the negative pressure regulating valve 9 that opens and closes the opening, thereby supplying a signal negative pressure diluted with the atmosphere according to the intake air amount and load to the exhaust recirculation control valve 4, and controlling the opening degree of the valve body 3. Adjustment is made to recirculate a predetermined amount (rate) of exhaust gas into the intake air.

At this time, the signal negative pressure in the first negative pressure signal path 8 is diluted with the atmosphere in response to the intake air amount as described above, so it becomes weaker than the signal negative pressure in the second negative pressure signal path 21, preventing a reverse reaction. Negative pressure in chamber A at valve 25 is greater than negative pressure in chamber B (absolute value)
Therefore, the valve body 25 d closes the communication hole 25 b and both passages 8, 2
1 can be substantially independent.

As a result, the valve body 3 and the negative pressure advance device 22 provided in the exhaust gas recirculation passage 2 are controlled independently of each other.

In this way, in a vehicle speed range below a predetermined speed, exhaust gas recirculation is performed to reduce NOx, and the ignition advance angle is advanced to obtain good fuel efficiency.

However, in the area near the fully closed throttle valve 6, the negative pressure outlet port)-8a
Since the pressure at is atmospheric pressure, there is no exhaust gas recirculation.

In addition, when the vehicle reaches a high speed operating state of a predetermined vehicle speed or higher, in which knocking is likely to occur due to movement of the knocking zone with the conventional ignition advance angle, the contact of the switch 28 is closed, the solenoid 26 is energized, and the electromagnetic on-off valve 24 is opened.

For this purpose, the atmosphere flows into the second negative pressure signal passage 21 and is introduced into the negative pressure working chamber 22a of the negative pressure advance device 22, thereby delaying the ignition advance angle and preventing the occurrence of knocking.

At the same time, the atmosphere introduced into chamber A of the check valve 25 opens the valve body 25 d, opens the communication hole 25 b, and flows into the first negative pressure signal passage 8 as described above.

Therefore, the signal negative pressure in the first negative pressure signal path 8 and the second negative pressure signal path 21 is diluted with the atmosphere.

For this reason, the opening degree of the exhaust gas recirculation control valve 4 becomes smaller or is closed, so that the exhaust gas recirculation is reduced or stopped.

That is, the instability of the engine due to the delay in the ignition advance described above is prevented by reducing or stopping the exhaust gas recirculation.

On the other hand, as mentioned above, the atmosphere flows in through the check valve 25 and the first
At the time when the signal negative pressure of the second negative pressure signal path 8 is further diluted with the atmosphere, the signal negative pressure of the second negative pressure signal path 21 is also diluted with the atmosphere, so that the ignition timing is adjusted by the negative pressure advance device 22. The advance angle is delayed, which prevents knocking due to early ignition and increases output, and also prevents a sudden rise in combustion temperature, preventing the generation of harmful exhaust components and overheating of various parts.

In addition, when performing exhaust gas recirculation, the air-fuel ratio of the air-fuel mixture is set to be richer than the stoichiometric air-fuel ratio to prevent various problems with the combustion suppressing effect (deterioration of ignitability, reduction in output, etc.) that accompany exhaust gas recirculation. It is preferable to cancel the rich side setting of the air-fuel ratio by increasing the amount of intake air or decreasing the fuel supply in synchronization with the decrease or stop of exhaust gas recirculation.

In the illustrated embodiment, the suction negative pressure introduction passage 32 for operating the power valve 31 of the carburetor is controlled by a second electromagnetic on-off valve 33 at a low speed
When the speed is less than 5 km/h, the air is opened to the atmosphere and the power pulp 31 is operated to set the air-fuel ratio to the rich side.

At this time, as mentioned above, exhaust gas recirculation is reduced or stopped near the fully closed area of the throttle valve 6, but in this region, the air-fuel ratio rich side setting is not canceled, improving engine startability and stabilizing idling rotation. let

Further, when the speed exceeds the above-mentioned speed, the air is shut off and only the suction negative pressure is applied, thereby controlling the power valve 31 to be inactive and canceling the above-mentioned rich side setting of the air-fuel ratio.

As explained above, according to the present invention, until the vehicle speed reaches a predetermined high-speed driving range, exhaust gas recirculation, ignition timing advance control and mixture rich setting are performed in accordance with this exhaust gas recirculation. It prevents the generation of harmful exhaust components from the engine, and at the same time prevents deterioration of ignitability and output reduction due to exhaust gas recirculation, reduces or stops exhaust gas recirculation near the fully closed throttle valve, and improves startability by setting the mixture to the rich side. The aim is to improve engine speed and stabilize engine idle rotation.

In addition, after the vehicle speed reaches a predetermined high-speed driving range, exhaust gas recirculation is reduced or stopped, and the ignition timing is advanced accordingly, thereby ensuring the high output required for so-called high-speed driving. It is possible to prevent knocking and achieve stable combustion in the engine.

Therefore, it is possible to prevent overheating of each part of the exhaust system, especially the exhaust after-treatment device.

Furthermore, since the above-mentioned exhaust gas recirculation control and ignition timing advance control are performed synchronously by the same electromagnetic on-off valve, the control mechanism can be simplified and economical, and synchronization accuracy can be increased. Therefore, the driving characteristics of the vehicle will not be temporarily deteriorated.

BRIEF DESCRIPTION OF THE DRAWINGS The figure is a sectional view of essential parts showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Intake passage, 2... Exhaust recirculation passage, 4... Exhaust recirculation control valve, 7... Negative pressure working chamber, 8... First negative pressure signal passage, 8a... No. 1 negative pressure outlet port, 9...
・Negative pressure regulating valve, 19...Second negative pressure extraction port, 21
...Second negative pressure signal path, 22...Negative pressure advance device,
24... First electromagnetic on-off valve, 25... Check valve, 28
... switch (vehicle speed detection means), 31 ... power valve, 32 ... suction negative pressure introduction passage, 33 ... second electromagnetic on-off valve.

Claims (1)

[Scope of utility model registration request] A negative pressure-responsive exhaust recirculation control valve provided in the exhaust gas recirculation passage and a first negative pressure take-out port located downstream of the throttle valve as the opening increases upstream of the throttle valve in the engine intake passage when the throttle valve is fully closed. The atmospheric dilution ratio in the first negative pressure signal path is varied by a negative pressure regulating valve that is connected via the first negative pressure signal path and responds to the venturi negative pressure of the venturi section of the carburetor and the exhaust pressure of the engine. The exhaust gas recirculation device configured as shown in FIG.
a negative pressure advance device in which a second negative pressure take-out port opened at a position of the engine intake passage which is opened and closed in substantially synchronization with the negative pressure take-out port of the engine is connected via a second negative pressure signal passage; a mixture enrichment device that responds to the suction negative pressure at a downstream position and enriches the mixture when the suction negative pressure signal decreases; a normally closed first on-off valve that opens the second negative pressure signal passage to the atmosphere; and a normally closed first on-off valve that opens the second negative pressure signal passage to the atmosphere; a second check valve that communicates with the air so as to permit the flow of air only when the vehicle speed is in the air-fuel mixture enrichment device; An internal combustion engine for a vehicle, characterized in that it is provided with an on-off valve.