JPS6223562A - Exhaust purifying system for internal-combustion engine - Google Patents

Abstract

PURPOSE:To aim at enhancing the quality of exhaust emission in the initial stage of a steady state operation, by enriching the air-fuel ratio of mixture upon detection of an acceleration and for a predetermined time after extinction of a detection signal therefor. CONSTITUTION:Solenoid valves 6 disposed in auxiliary air-bleeds 4, 5 in a carburettor B, are opened and closed by means of a vacuum-operated type switch 55. When a clutch e0is disengaged during acceleration, a detection switch 31 is turned on to open a solenoid valve 50 for a duration means K. The, intake vacuum is fed into a vacuum tank 51 through a vacuum passage 54 and therefore is accumulated in the tank 45, and therefore, the switch 55 is turned off to deenergize the solenoid valves 6 so that the auxiliary air-bleeds 4, 5 are closed, Accordingly the amount of fuel flowing out from a slow system port 10 is increased, resulting in increasing the air-fuel ratio of mixture. At this time, even if the clutch 30 is engaged to turn off the switch 31 so that the solenoid valve 50 is closes, the vacuum in the vacuum tank 51 is gradually decreased by means of an orifice 52, and therefore, the air-fuel ratio of mixture is enriched.

Description

[Detailed description of the invention] The present invention relates to an exhaust gas purification system for an internal combustion engine.

Generally speaking, in internal combustion engines, re-combustion devices such as a reactor (including an exhaust manifold with a reactor function) and a catalyst device are attached to the engine exhaust system as a measure to remove air-containing components from the exhaust gas. , C0 is re-burned and removed. According to this reburning device, the more combustion components in the exhaust gas flowing into the reburning device, the better the reburning efficiency of HC and Go. Therefore, from the perspective of purifying HC and Co, it is possible to enrich the air-fuel mixture supplied to the engine and increase the amount of IC9Co in the exhaust gas, but on the other hand, this will worsen fuel efficiency, so from the perspective of fuel efficiency, the engine Preferably, the fuel supply device supplies a relatively lean air-fuel mixture.

By the way, during so-called steady operation in which the engine is operated while maintaining a constant operating state, combustion stability is good even if the air-fuel ratio of the supplied air-fuel mixture is set relatively lean, so the exhaust emissions from the combustion chamber are comparatively low. In addition, since the temperature within the afterburner is maintained at a relatively high temperature, HC and Co in the exhaust gas after passing through the afterburner can be reduced as much as possible. However, when the engine is accelerating,
During the acceleration stage, the combustion stability of the engine becomes worse than during steady operation, and 11c, a combustion component, is emitted from the engine.
, C0fi increases to some extent, but during such operation, the temperature inside the afterburner tends to decrease compared to during steady operation, and the volume of exhaust gas increases, so as shown in Figure 1, during such operation, There is a problem in that the amount of IC and Co released into the atmosphere increases without being completely removed by the reburning device compared to during steady operation. In particular, in the case of internal combustion engines as well as automobile engines, since the above-mentioned operation is carried out exclusively when driving in urban areas, there is a strong demand for improvements in this respect from the viewpoint of preventing air pollution. Furthermore, it is important to improve fuel efficiency when driving in the suburbs, where steady driving is performed.

In view of such circumstances, the present invention supplies a richer air-fuel mixture than during steady operation during acceleration operation of the engine and during the initial stage of steady operation when transitioning from acceleration operation to steady operation.
Actively increases HC and COff1, which are combustion components discharged from the engine, and significantly promotes the combustion of these HC and Co in the afterburner to ensure the temperature in the afterburner even during the operation, The afterburning device functions effectively to minimize IIC and Co emissions over the entire operating range of the engine, and improves the fuel efficiency of the engine by supplying a lean air-fuel mixture during long-term steady operation of the engine. We provide an exhaust purification system that balances the two.

Hereinafter, the acceleration operation of the engine and the initial stage of steady operation when the engine shifts from acceleration to steady operation, which are the particular targets of the present invention, are hereinafter referred to as "acceleration operation and steady operation immediately after acceleration." . Embodiments of the present invention will be described in detail below with reference to the drawings.

In Fig. 2, A is an air cleaner, B is a carburetor, C is an intake manifold, D is an engine body, E is a transmission, F is a fuel actor as a re-combustion device, and a passage G is provided upstream of the reactor F. A predetermined amount of secondary air is supplied according to the engine operating condition through the HC, and the HC is discharged from the engine under the supply of this secondary air.

It is configured to efficiently oxidize CO.

Here, in the present invention, an air-fuel ratio control device H is provided which makes the air-fuel ratio of the supplied air-fuel mixture richer than the air-fuel ratio during steady operation during acceleration operation of the engine and during steady operation immediately after acceleration. This air-fuel ratio control device H includes a detection means I that detects the operating state immediately before the engine becomes accelerated and/or an accelerated operating state, and detects the auxiliary air amount of the carburetor B based on the detection signal of the detection means I. and a sustaining means for continuing the control operation of the control means J for a predetermined period of time even after the detection signal disappears.

To explain this in detail with reference to FIG. 3, each of the main and slow air bleeds 2.3 of the carburetor B is provided with an auxiliary air bleed 4.5, and these auxiliary air bleeds 4.5 are controlled. Means J is an on-off valve that indirectly controls the amount of fuel flowing out, for example, the auxiliary air bleeds 4 and 5 are opened during steady operation of the engine, and the auxiliary air bleeds 4 and 5 are opened during acceleration operation and during steady operation immediately after acceleration. A solenoid valve 6.6 which is operated to close is interposed.

In other words, by setting the diameters of the main, slow fuel jets 7a, 8a, main slow air bleed jet, etc., this carburetor B has good fuel efficiency and exhaust emissions during steady operation when the solenoid valve 6.6 is fully open. For the purpose of reducing the amount of fuel flowing out from the main nozzle 9 or the slow boat 10 (including the idle boat 10a and the slow boat 1Ob), the amount of fuel flowing out from the main nozzle 9 or the slow boat 10 (including the idle boat 10a and the slow boat 1Ob) is reduced to a mixture with a relatively thin air-fuel ratio, for example, a mixture with an air-fuel ratio of about 14 to 17. In addition, during acceleration operation when the solenoid valve 6°6 is fully opened, and during steady operation immediately after acceleration, a relatively rich air-fuel mixture with an air-fuel ratio of about 11 to 13 is obtained, and during such operation the engine The setting is such that the amount of Ic, CO, which is a combustion component emitted from the engine, can be actively increased. 11 is an intake passage, 12 is a venturi, 13 is a throttle valve, and 14 is a throttle valve] 3 A power device that opens and closes according to changes in intake negative pressure taken out from a negative pressure take-out port 15 opened in the intake passage 11 downstream; 16 is a float chamber, 7 is a main fuel passage, and 8 is a slow fuel passage.

Next, in this embodiment, the detection means I selects the gear position of the transmission E in accordance with the speed range when the clutch 30 (the clutch pedal is shown in the figure) is activated and the engine is accelerated. , and since such a gear position selection operation involves clutch disengagement and engagement operations,
By detecting the operating state of this clutch, it is possible to easily determine the state immediately before the engine is in the acceleration operation state and the state during the acceleration operation. This detection switch 31 is connected to the clutch 3
0 is disconnected, that is, when the clutch pedal is depressed, it is turned on and the voltage of the battery L is applied to the solenoid valve 50, which is a sustaining means described later, to excite the coil 50a, and the valve body 5
Operate 0b to open the valve. Further, when the clutch 30 is connected, the switch 31 is turned off, and the coil 5 of the solenoid valve 50 is turned off.
Qa is demagnetized and the valve body 50b is operated to close.

The sustaining means includes a negative pressure tank 51 in which an orifice 53 is provided at the atmosphere opening port 52 so that suction negative pressure taken from a negative pressure source, for example, an engine intake system, is accumulated and the negative pressure is gradually diluted. , a solenoid valve 50 that is interposed in a negative pressure passage 54 that communicates the negative pressure tank 51 and the negative pressure outlet 15 and that is opened and closed by the detection switch 31; The auxiliary air bleed 4.5 is operated by a negative pressure operated switch 55 which is turned on and off to open and close the electromagnetic valves 6, 6 installed in the auxiliary air bleed 4.5. The switch S5 is a negative pressure tank 51 that acts on the negative pressure chamber 55a.
For example, when the negative pressure inside is O~-50m111g, the ON operation is performed, and when the negative pressure value (absolute value) increases beyond this value, the operating rod 55c is pulled through the diaphragm 55b and the OFF operation is performed. . 56 is a check valve installed in the negative pressure passage 54 between the negative pressure tank 51 and the solenoid valve 50;
indicates the ignition switch. Here, a time constant is set in the sustaining means assuming a normally used acceleration driving pattern based on a driving pattern corresponding to an urban driving state.

With this configuration, in order to change the gear position of the transmission E according to the speed range when the engine accelerates, the clutch 30
When the clutch 30 is disengaged, the accelerator pedal (not shown) is released, the throttle valve 13 is fully closed, and engine suction negative pressure with a high negative pressure value is generated downstream of the throttle valve 13. ), the detection switch 31 is turned on and the solenoid valve 50 serving as the sustaining means is opened. As a result, engine suction negative pressure with a high negative pressure value is accumulated in the negative pressure tank 51 via the negative pressure passage 54, and the switch 55 is turned off.

By turning off the switch 55, the coils 6a, 6a of the solenoid valves 6, 6 are demagnetized, and the valve bodies 6b, 6b close the auxiliary air bleed 4.5, reducing the air bleed amount, that is, the auxiliary air 1, and Specifically, the amount of fuel flowing out from the main nozzle 9 or slow system port 10 is increased to control the air-fuel mixture to a predetermined rich air-fuel ratio (A/F=11 to 13). Even if the gear position switching operation of the transmission E is completed and the clutch 30 is connected, the detection switch 31 is turned off, and the solenoid valve 50 serving as the sustaining means is closed, the negative pressure inside the negative pressure tank 51 is Since the pressure is gradually diluted by the orifice 53, the off-operation of the switch 55 is maintained for a certain predetermined period of time, so that the electromagnetic valves 6, 6 are kept closed, and the aforementioned fuel control action is maintained. Therefore, even if the clutch 30 is continuously engaged and disconnected during acceleration, no electricity is generated, and this fuel increase effect continues especially until the initial stage of steady operation following engine acceleration. Therefore, during such acceleration operation and during steady operation immediately after acceleration, the air-fuel ratio is enriched, and the amount of HC and Co, which are combustion components discharged from the combustion chamber of the engine, is actively increased to increase the reactor F. As a result of promoting the oxidation reaction of IIC and Co by introducing an appropriate amount of secondary air, the temperature inside the reactor F can be maintained at a high temperature due to this oxidation exothermic reaction, and the purification efficiency of IIc and Co can be maintained at a high level. It is. In addition, especially the detection means ■
A switch 31 that detects the operating state of the clutch 30 as
By using this, the clutch 30 is already activated before acceleration operation.
Since the reactor F is separated, the air-fuel ratio is enriched in advance before the acceleration operation, and the temperature inside the reactor F can be quickly raised.

In addition, in the above, both main and slow air bleed 2
．． 3 is connected to an auxiliary air bleed 4.5, and a solenoid valve 6 is connected to both auxiliary air bleeds 4, 5 as a control means J.
．． 6 is installed, but this auxiliary T7 block II-K)
- Regular score # may be provided only on either main slow air lead 2 or 3.

Figures 4.5 show other embodiments of the detection means (2). FIG. 4 shows an example in which a gear switch 32 which issues a detection signal when the transmission E is switched to a speed range lower than the top gear position of the transmission E is used as the detection means (2). This means that in general automobiles, etc., the driving conditions that use the top gear or higher speed range, except for the first short period of time, are steady driving, and the driving conditions that use the lower speed range than the top gear are during acceleration driving. This is because it is a typical driving condition. For example, when the transmission is in 4 forward speeds, when the transmission is operated to the 4th speed (top) position, the control rod 33 at 433a
, the rod 34 of the gear switch 32 falls down due to the elastic force of the spring 35, and the conduction between the terminals 37 and 37 through the conductor 36 is cut off.
In 3rd speed), the tip of the rod 34 collides with the circumferential surface of the control rod 33, the rod 34 is moved down against the elastic force of the spring 35, and the terminals 37 and 37 are electrically connected via the conductor 36. It emits a detection signal such as .

When the transmission has three forward speeds, the third speed or top gear is the first speed, the second speed or the low speed range.

In addition, if the transmission has 5 forward speeds with overdrive, the 4th gear is the top gear, the 5th gear is a high speed range that is higher than the top gear, and the 3rd to 1st gears are the low speed range. .

For a similar purpose, in an internal combustion engine using an automatic transmission, as shown in FIG. 5, a control valve ( A pressure switch 39 is provided in the hydraulic system 38 (not shown). This pressure switch 39 is connected to the hydraulic chamber 3
When 9a is at a predetermined pressure (pressure when in top gear), the diaphragm 39c is displaced upward by overcoming the force of the atmosphere and the spring 39b, turning off the contact 39d, and the hydraulic pressure is changed to a lower speed range than the top gear. The voltage drop in the system 38 causes the diaphragm 39c to move downward, turning on the contact 39d and emitting a detection signal.

Note that it is also possible to use a throttle opening sensor, an accelerator pedal rotation position sensor, or an engine suction negative pressure sensor as the detection means.

In the above embodiment, a solenoid valve was used as the control means J to control the amount of auxiliary air in the carburetor B, but a negative pressure operated valve may also be used. The embodiment shown in FIG. 6 uses such a negative pressure operated valve to control the amount of auxiliary air. When a predetermined value of engine suction negative pressure is introduced into the negative pressure chamber 25a during acceleration operation and during steady operation immediately after acceleration, the valve body 25c is advanced through the diaphragm 25b to the bleed 4, and the auxiliary air bleed is A negative pressure operated valve 25 that closes the valve 4 is interposed. In the case of this embodiment, the switch 55 of the sustaining means shown in FIG. 3 is not required, and it is sufficient to communicate the negative pressure tank 51 and the negative pressure chamber 25a of the negative pressure operating valve 25. In addition,
In this embodiment, instead of the orifice 53 provided at the atmosphere opening port 52 of the negative pressure tank 51, an orifice 53 made of sintered metal is used to perform the same function as an orifice. If a sintered alloy is used as a sintered alloy, the effective ventilation area can be made as small as possible compared to the orifice, and therefore,
A predetermined sustained action can be obtained by reducing the capacity of the negative pressure tank 51. In the embodiment shown in FIG.
In the embodiment shown in the figure, a check valve 57a and an orifice 57b made of a sintered metal are provided in the negative pressure passage 54 communicating the negative pressure outlet 15 and the negative pressure chamber 25a of the negative pressure operating valve 25 as sustaining means. and a detection means I.
A three-way solenoid valve 58 having an atmosphere opening port 58a operated by the three-way solenoid valve 58 is interposed therebetween.

When engine suction negative pressure is introduced, the valve device 57 opens a check valve 57a to quickly transfer this suction negative pressure to the negative pressure operating valve 2.
However, when the atmosphere is introduced into the negative pressure chamber 25a, the check valve 57a is sealed, and the orifice 57b made of sintered metal prolongs the dilution time of the negative pressure in the negative pressure chamber 25a by the atmosphere. The closing operation of the negative pressure operated valve 25 is maintained for a predetermined period of time.

In other words, in this embodiment, when the detection means (2) operates during accelerating operation of the engine, the three-way solenoid valve 58 closes the atmospheric opening boat 58a, while opening the negative pressure passage 54, and as a result, the engine suction negative pressure is introduced into the negative pressure chamber 25a of the negative pressure operated valve 25 through the check valve 57a of the valve device 57, and the valve body 2
5c closes the auxiliary air bleed 4 to increase the amount of fuel flowing out. Then, when the detection action of the detection means (2) stops, the three-way solenoid valve 58 blocks the negative pressure passage 54, while communicating the atmosphere opening port 58a with the passage on the valve device 57 side to introduce the atmosphere. , the circulation of this atmosphere is significantly restricted by the sintered metal 57b, and the negative pressure operated valve 2 is completely restricted.
The dilution time of the negative pressure in the negative pressure chamber 25a of No. 5 is prolonged, and the closing operation of the negative pressure operated valve 25 is maintained for a predetermined period of time.

On the other hand, other embodiments of the sustaining means that can be adopted when a solenoid valve is used as the control means include an electric timer circuit shown in FIG. 8 or a mechanical-electric timer circuit shown in FIG.

The electrical timer circuit shown in FIG. 8 combines a time constant circuit 6I consisting of a resistor 59 and a capacitor 60 and a switching transistor 62 in a circuit including a battery L, an ignition switch open 1 solenoid valve 6, and a detection switch I. Even after the detection switch I is switched from on to off, the switching transistor 62 remains on for a predetermined time determined by the time constant circuit 61, and the solenoid valve 6 continues to be energized. be.

The mechanical-electric timer circuit shown in FIG. 9 is a combination of mechanical switches such as a self-holding relay switch 63 and a heater bimetal switch 64 in place of the time constant circuit 61 and switching transistor 62. The action of a self-holding relay 63 that energizes the solenoid valve 6 when the detection switch ■ is turned on and continues to energize it even after the detection switch ■ is turned off, and the heater 64a that generates heat when energized
Due to the action of the bimetal 64c, which is heated and deforms after a predetermined time to turn off the contact 64b, the electromagnetic valve 6 is maintained in the ON state for a predetermined time even after the detection switch I is turned off.

In these cases, instead of connecting the solenoid valve directly to the circuit, a relay switch or the like may be inserted in the circuit, and the solenoid valve may be operated via this relay switch. Of course.

In addition, in the above, the intake air-fuel mixture supplied from the carburetor is set to a predetermined lean air-fuel ratio based on the steady operation of the engine, and the amount of fuel is increased by controlling the amount of auxiliary air during acceleration operation and during steady operation immediately after acceleration. Although the outflow amount was increased indirectly to obtain a rich air-fuel ratio, the air-fuel mixture was set to be supplied at a predetermined rich air-fuel ratio based on acceleration operation and steady operation immediately after acceleration. However, during steady operation, auxiliary air may be supplied to reduce the air-fuel ratio.

Furthermore, in each of the above embodiments, the air-fuel ratio is enriched during acceleration operation and during steady operation immediately after acceleration by controlling the amount of auxiliary air from the auxiliary air bleed of the carburetor. That is, the supply of auxiliary air may be controlled by supplying the auxiliary air downstream of the throttle valve. In this case as well, the flow rate of the auxiliary air is controlled by the cooperative action of the detection means and the sustaining means.

11-According to the unprecedentedly great invention, the detection means detects the state immediately before the engine accelerates and/or the accelerated operation state, and the sustaining means maintains the detection signal even after the detection signal disappears. In order to maintain this and operate the control means to control the amount of auxiliary air in the carburetor and enrich the air-fuel ratio, it can be used not only when the engine is accelerating, which is the operating state used exclusively in city driving, but also during the initial stage of steady operation. , by adjusting the air-fuel ratio of the intake mixture rather than during steady operation, H
Since C and C0jk are actively increased and the oxidation exothermic reaction in the afterburner is actively carried out, the temperature inside the afterburner is sufficiently raised even during such operation.

It is capable of efficiently removing CO, and is capable of supplying a mixture with a predetermined lean air-fuel ratio that improves fuel efficiency and exhaust emissions during steady driving, which is the driving state used exclusively in suburban driving. This has the advantage of improving the functionality of the reburning device and improving engine fuel efficiency.

[Brief explanation of the drawing]

Fig. 1 is a characteristic diagram showing IIc and Co emission maximum of the engine, Fig. 2 is a system diagram of the system of the present invention, and Fig. 3 is a diagram of the system of the present invention.
4.5 is an explanatory diagram of the detection means of each field, FIGS. 6 and 7 are explanatory diagrams of the control means of each field, and FIGS. 8 and 9 are diagrams of the continuation of each field, respectively. It is an explanatory diagram of means. B... Carburetor, D... Engine body, E... Transmission,
F... Reburning device, H... Air-fuel ratio control device, ■... Detection means, J... Control means, K... Continuation means. Simultaneously with Figure 1 - Figure 2 Figure 6

Claims (1)

[Claims] (1) In an automobile internal combustion engine equipped with a reburning device in the exhaust system, the air-fuel ratio of the supplied air-fuel mixture during acceleration operation and during steady operation immediately after acceleration is richer than that during steady operation. A fuel ratio control device is provided, and the air-fuel ratio control device includes a detection means for detecting a state immediately before an acceleration operation state and/or an acceleration operation state to generate a detection signal, and a detection means that generates a detection signal even after the detection signal disappears. a means of sustaining the
and a control means which is a valve device that opens and closes in response to a signal from the sustaining means and controls the amount of auxiliary air in the carburetor to enrich the air-fuel ratio. purification system.