JPS588244A - Suction system air-fuel ratio controller for catalytic device - Google Patents

Abstract

PURPOSE:To simplify the controller by varying a amount of the secondary suction air or the fuel to be fed to the suction system thereby varying the air-fuel ratio forcefully near to the theoretical ratio. CONSTITUTION:An air-fuel ratio controlling means is placed while conducting the secondary air path 14 to the suction system such as the suction path 6, carburetor 4, etc. to vary the air-fuel ratio provided to the internal combustion engine 8 near to the theoretical ratio. Here a main side secondary air path 14m having the delivery port 17 between the main jet 32 at the upstream of the Venturi 18 and the jet 31, a slow side secondary suction air path 14s having the delivery opening 34 in the proximity of the slow port 30 areprovided, then the paths 14m, 14s are jointed to conduct to the path 19 and opened to the atmosphere. When controlling a solenoid valve 36 placed at said joint by means of a multivibrator 38, the air-fuel ratio can be varied near to the theoretical ratio easily.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a catalyst device that forcibly changes the air-fuel ratio around the stoichiometric air-fuel ratio by changing the amount of secondary air introduced into the intake system in front of the combustion chamber. The present invention relates to an intake system air-fuel ratio control device.

In order for a catalyst device, such as a three-way catalyst device, to function effectively, the components of the exhaust gas introduced into the device, particularly the oxygen concentration, must be controlled with great precision. Therefore, when using a three-way catalyst device, it is necessary to strictly control the secondary air to maintain the air-fuel ratio within a window as shown in FIG. Note that this window is narrow, ranging from stoichiometric air-fuel ratio (stoichiometric ratio) of 1450.1 to ±0.15. For this reason.

02 sensors are used and a so-called air/fuel ratio feedback system is required.

However, the conventional system described above has the disadvantages that the control method is extremely complicated, and as a result, the control device is also complicated, expensive, and frequently malfunctions. In addition, since there is a time delay in the system in the feedback system #, if a fast cycle control is performed to eliminate this drawback, the 92 engine with a large amplitude of air-fuel ratio may cause hunting or the three-way catalyst may deteriorate. There is also the inconvenience of coming.

Therefore, the purpose of this invention is to achieve NO.
To realize an intake system air-fuel ratio control device for a catalyst device which can purify x, improve the durability of the catalyst, do not induce hunting in two engines, and contribute to improving fuel efficiency.

A detailed explanation of the present invention will be given below based on the drawings.In order to make the invention easier to understand, the graph of FIG. 7 will be explained first.
The horizontal axis shows the air-fuel ratio, and shows how the purification rate changes due to periodic fluctuations in the air-fuel ratio that fall outside the stoichiometric air-fuel ratio, and forced fluctuations between lean and rich. This shows the results of an experiment to determine whether Note that this period is, for example, 0.1 to 2 seconds and the air-fuel ratio is approximately -±0.2 to ±1. According to the graph in FIG. 1, it can be seen that although the overall purification rate is a little lower, all three graphs for Co, HC, and NOX exhibit characteristics with gentler shoulders and wider tails. In other words, the window is somewhat wider than under normal operation. This is thought to be due to oxygen adsorption (oxygen storage) of the catalyst. And by varying the air-fuel ratio in this way, NO! in the lean range! It also has the secondary effect of improving the purification rate.

Focusing on this property, a control device is constructed as shown in FIG. That is, 2 is an air cleaner, 4 is a carburetor, 6 is an intake vent, 8 is an internal combustion engine, 10 is an exhaust passage, and 12 is a three-way catalyst device. . A secondary air passage 14 is communicated with the intake system such as the intake passage 6 and the carburetor 4.
The starting end of 4 is preferably communicated with the air cleaner 2. In the middle of this secondary air passage 14, there is an air-fuel ratio control means 1 for varying the air-fuel ratio, which includes a solenoid valve, etc., which will be described later.
6 to intervene. The control means 16 changes the air-fuel ratio input to the internal combustion engine 8, that is, the air-fuel ratio of the three-way catalyst device 112, around the stoichiometric air-fuel ratio. The operation of this control means 16 can be controlled in various ways as follows. In other words.

(1) Adjust the ratio of occupied time on the lean side and rich side of the air-fuel ratio to an appropriate value. For example, 1:IK, a certain (2) air-fuel ratio V is varied in response to engine operating conditions such as engine speed and load, or is not varied and is uniformly varied over the entire area during engine operation.

Next, a specific example will be explained. FIG. 4 shows three embodiments of the present invention. That is, arrow 1. I
There are three examples indicated by I and I.

First, the air bleed system of the first embodiment (drawn with dotted lines) indicated by arrow l will be described. In fig.

18 is a venturi, 20 is a float chamber, and 22 is a throttle valve.

26 is a main passage, 28 is a main nozzle, and 30 is a slow boat. An inlet 32 is provided on the upstream side of the venturi 18.
The inlet port 32 is provided as the opening end of the secondary air passage 14, and the secondary air passage 14 is provided with a discharge port 34 near the slow port 30 as the opening end thereof. Also, these 2
A solenoid valve 36 is provided in the middle of the next air passage 14.

The opening and closing of this solenoid valve is controlled by a multivibrator blade serving as a transmitter. In addition, when operating this multivibrator, if the secondary air passage 14 is to be controlled to open and close at a constant cycle, the multivibrator blades may be set to bistable multi, or if the cycle is changed appropriately, it may be set to monostable multi. .

If configured as in the first embodiment, the air-fuel ratio can be changed between the front and rear sides of the stoichiometric air-fuel ratio by appropriately opening and closing the solenoid valve 36, and the preferred purification shown in FIG. 2 can be achieved. It is possible to obtain characteristics that indicate the rate. Therefore, although the configuration is extremely simple, highly efficient exhaust gas purification can be achieved using the three-way catalyst. In addition, if the air-fuel ratio is set so that the average remainder is 1 in, this will not only prevent the inconvenience of the air-fuel ratio from being out of tune as in the past and have a negative effect on exhaust purification, but it will also further improve the NOx purification rate. This makes it possible to utilize secondary effects and also improve fuel efficiency.

Next, the second embodiment (dotted chain line drawing) shown by the arrow ■ in Fig. 4
The jet method is explained in detail. This embodiment is characterized by a secondary air passage 1 connected to the solenoid valve 36-2.
The discharge date-2, which is the opening end of 4-2, is provided in the middle of the main passage 26, and air is mixed in advance into the air-fuel mixture ejected from the main nozzle 28, so that the fuel vaporization is improved. Note that 36-2 is a solenoid valve.

Next, an explanation will be given of the intake pipe system of the third embodiment (two points @ line drawing) indicated by the arrow ■. The feature of this third embodiment is that the discharge port 14-3, which is the opening end of the secondary air passage 14-3, is opened into the intake passage 6 on the downstream side of the throttle valve 22. Note that 36-3 is a solenoid valve. With this configuration, the secondary air passage can be configured with a simple configuration without modifying the vicinity of the carburetor, which has a complicated structure.

The disadvantage of engine instability caused by injecting secondary air into the intake system can be determined by comparing the window widening due to air-fuel ratio fluctuations with the stability of one engine, and it is possible to determine whether the engine has the desired performance. can be obtained, and there is no inconvenience of unnecessarily incurring the drawback of engine instability. - Note that this invention is not limited to the above embodiments and can be modified in various ways.

For example, in the above embodiment, the air-fuel ratio was controlled by injecting secondary air only into the intake system, but the air-fuel ratio can be controlled in combination with a method in which secondary air is injected into the exhaust system, that is, the downstream side of the internal combustion engine. It is also possible to have a configuration in which this is done.

Also, NO! It is also possible to use the EGR method effective for reduction and the method of the present invention in combination, and in this way, further exhaust purification can be achieved without impairing the performance of the engine over the entire operating range.

Yet again. In the above embodiments, a three-way catalyst device has been described, but it goes without saying that the present invention can also be applied to an oxidation catalyst or a reduction catalyst.

As is clear from the above detailed description, the present invention is not a feedback control system using an O2 sensor like the conventional device, but can be configured extremely easily as an open loop system, and is capable of purifying exhaust gas. can. Further, there is no time delay in the system as in conventional devices, the fluctuation period and amplitude of the air-fuel ratio are predetermined, there is no instability such as hunting in the engine, and there is no inconvenience such as deterioration of the catalyst. Furthermore, if the average air-fuel ratio V is set to the lean side, fuel efficiency can be improved.Also, since the air-fuel ratio fluctuation period, amplitude, and its deviation can be freely set, the performance of the two engines can be taken into consideration. This can improve the durability of the engine and catalyst device.

[Brief explanation of the drawing]

Figure 1 is a graph showing the characteristics of the three components of air-fuel ratio and purification rate under steady-state operation, Figure 2 is a graph showing the purification rate when the air-fuel ratio is varied around the stoichiometric air-fuel ratio, and Figure 3 is a graph showing the purification rate when the air-fuel ratio is varied around the stoichiometric air-fuel ratio. The system diagram showing the principle of this invention, Figure 4, is the first diagram of this invention.
Figure 6 is a schematic diagram showing three embodiments. In the figure, 2 is an air cleaner and 4 is a carburetor. 6 is an intake passage, 8 is an internal combustion engine, IO is an exhaust passage, 12
1 is a three-way catalyst device, 14 is a secondary air passage, and 16 is an air-fuel ratio control means. Agent Patent Attorney Yoshimi Saigo Figure 1 Figure 2 Procedural Amendment (Voluntary) March 1, 1980 Commissioner of the Patent Office Shima 1) Haruki Tono 1, Case Indication q# Application 1982-105698 2 Invention Name of catalytic device intake system air-fuel ratio control device 3, relationship with the case of the person making the amendment Patent applicant 300 Takatsuka, Kamimura, Hamana, Shizuoka Prefecture (208) M-Ki Jidosha Kogyo Co., Ltd. Representative Osamu Kagiri 4; Agent 〒105 Telephone 438-2241 (
Representative) 3-4-17-6 Toranomon, Minato-ku, Tokyo Subject of amendment (1) Full text of specification (2) Drawing 7・Contents of amendment , , / , , ,
, 1. Full text correction specification 1. Title of the invention Intake system air-fuel ratio control device for catalyst device 2. Claims In an internal combustion engine that performs exhaust purification by a catalyst device, a secondary intake system introduced into the intake system before the combustion chamber. 1. An intake system air-fuel ratio control device for a catalyst device, comprising an air-fuel ratio control means for forcibly changing the air-fuel ratio around a stoichiometric air-fuel ratio by changing the amount of air or fuel. 3. Detailed Description of the Invention This invention provides a catalyst device that forcibly changes the air-fuel ratio around the stoichiometric air-fuel ratio by changing the amount of secondary intake air introduced into the intake system in front of the combustion chamber. The present invention relates to an intake system air-fuel ratio control device. In order for a catalyst device, such as a three-way catalyst device, to function effectively, the components of the exhaust gas introduced into the device, particularly the oxygen concentration, must be controlled with great precision. Therefore, when using a three-way catalyst device, it is necessary to strictly control the secondary intake air and maintain the air-fuel ratio within the window as shown in Figure 1. The theoretical ratio) is about ±0.1 to ±0.15. For this reason, an e02 sensor is used, and a so-called air-fuel ratio feedback system is required. However, the control method of the conventional system described above is extremely complicated, and as a result, the control device is also complex, expensive, and prone to failure. There were drawbacks. Feedback control also has the disadvantage that there is a time delay in the system. Therefore, the purpose of this invention is to achieve NO.
It also purifies x and improves the durability of the catalyst. The object of the present invention is to realize an intake system air-fuel ratio control device for a catalyst device that can contribute to improving fuel efficiency. The present invention will be described in detail below based on the drawings. In order to facilitate understanding of this invention, we will first explain the graph in Figure 2.The vertical axis of this graph represents the purification rate (5), and the horizontal axis represents the air-fuel ratio.9. This shows the results of an experiment to see how the purification rate changes due to periodic fluctuations in the air-fuel ratio that interfere with the stoichiometric air-fuel ratio, and forced fluctuations from lean to rich. . Note that this period is, for example, 0
．． The air-fuel ratio Y is ±0.2 to ±111 degrees in 1 to 2 seconds. According to the graph in Fig. 1, although the overall purification rate is a little lower, it can be seen that all three graphs, Co, IC, and NOx, exhibit characteristics of gentle shoulders and further widening of the tails. Finally, the window is slightly wider than under normal operation. This is thought to be due to oxygen adsorption (oxygen stray) of the catalyst. When the air-fuel ratio is varied in this way, NO.
x A secondary effect of improving the purification rate is also obtained. Focusing on this property, a control device is constructed as shown in FIG. That is, 2 is an air cleaner, 4 is a carburetor, 6 is an intake passage, 8 is an internal combustion engine, lo is an exhaust passage, and 12 is a three-way catalyst device. A secondary intake air passage 14 is communicated with the intake system such as the intake passage 6 and the carburetor 4, and the starting end of the secondary intake air passage 14 is preferably communicated with the air cleaner 2. And this secondary intake air passage 14:i! An air-fuel ratio control means 16 for varying the air-fuel ratio consisting of a solenoid valve or the like, which will be described later, is interposed in the air-fuel ratio control section i. The control means 16 is used to vary the air-fuel ratio input to the internal combustion engine 8, that is, the air-fuel ratio of the three-way catalyst device 12, around the stoichiometric air-fuel ratio. The operation of the control means 16 can be controlled in various ways as follows. In other words. (1) The time occupied by the lean side and rich side of the air-fuel ratio should be set appropriately. For example, the ratio is set to 1:1, or the lean side is set to 2 and the rich side is set to 1, that is, 2:1. (2) The air-fuel ratio is varied in response to engine operating conditions such as engine speed and load, or is not varied and is made to vary uniformly over the entire area during engine operation. Next, a specific example will be described. FIG. 4 shows three embodiments of the present invention. That is, arrow 1. ■, 1
Here are three examples. First, the arrow! The air bleed system of the first implementation '@ (dotted line) will be explained in detail. In fig. 18 is a venturi, 20 is a float chamber, 22 is a throttle valve,
26 is the main passage, 28 is the main nozzle. 30 is a slow port, 33 is an idle/-), a main air jet 32 is provided upstream of the venturi 18, and as shown in the fourth figure, a main side having a discharge port 17 between the main air jet 32 and the jet 31. A 14m secondary intake air passage will be provided. Similarly, as shown in Figure 4, a secondary intake air passage 141 is provided on the slow side. The discharge opening 34 of this passage 14° is connected to the slow port 30.
Open to the nearby slow passage. And the main side and slow side secondary intake air passages 14□, 14. The two converge at the upstream portion and communicate with one passage 19, and this passage 19 is opened to the atmosphere. Further, a solenoid valve 36 is interposed in this confluence part, and this solenoid valve 36 is used as a multivibrator 38 which is a transmitter.
Opening/closing is controlled by Furthermore, this multivibrator 3
8, if the secondary intake air passage 14 is to be controlled to open and close at a constant cycle, the multivibrator 38 may be set to a bistable multivibrator, and if the cycle is to be changed appropriately, the multivibrator 38 may be set to a monostable i-multivibrator. If configured as in the first embodiment described above, the air-fuel ratio can be changed to both sides of the stoichiometric air-fuel ratio by appropriately opening and closing the solenoid valve 36, and the preferable purification shown in FIG. 2 can be achieved. It is possible to obtain characteristics that indicate the rate. Therefore, the configuration is extremely simple, and as shown in the table, highly efficient exhaust gas purification can be achieved using a three-way catalyst. Also, if the average air-fuel ratio is set to be on the lean side at this time, it will not cause the inconvenience of going out of the window and adversely affecting exhaust purification as in the past, but it will also improve the NOx purification rate. This makes it possible to take advantage of the practical effects and also improve fuel efficiency. Next, the second embodiment (dotted chain line drawing) shown by the arrow ■ in Fig. 4
The Uet method will be explained. This embodiment is characterized by a bypass 3 that bypasses the main jet 35.
7 is provided, and by opening and closing this pi/base 37 by a solenoid valve 36-2, the amount of fuel is increased or decreased, thereby changing the air-fuel ratio. Next, the intake pipe system of the third rear embodiment (drawn with two-dot chain lines) indicated by the arrow ■ will be explained. The feature of this third embodiment is that the discharge port 34-3, which is the opening end of the secondary intake air passage 14-3,
This is because the throttle valve 22 is opened to the intake passage 6 on the downstream side. Force 36-3 is a solenoid valve. With this configuration, it is possible to do this without having to modify the vicinity of the carburetor, which has a complicated structure.
The secondary air passage can be configured with a simple configuration. The inconvenience of engine instability caused by injecting secondary intake air into the intake system can be determined by comparing the window widening due to air-fuel ratio fluctuations and the stability of the nine engines, so that the desired performance can be achieved. The engine can be obtained without the inconvenience of unnecessarily incurring the disadvantage of engine instability. Note that this invention is not limited to the above-mentioned embodiments, and can be modified in various ways. For example, in the above-described embodiment, the air-fuel ratio was controlled by injecting secondary intake air only into the intake system. It is also possible to adopt a configuration in which air-fuel ratio control is performed in combination with a method of injecting secondary air into the downstream side of the exhaust system and the t99 mode connection. Moreover, it is also possible to use the EGR method effective in reducing NOx and the method of the present invention in combination. Further exhaust purification can be achieved without impairing engine performance over the entire operating range. Yet again. In the above embodiments, a three-way catalyst device has been described, but it goes without saying that the present invention can also be applied to an oxidation catalyst or a reduction catalyst. As is clear from the above detailed description, the present invention is not a feedback control system using a 0□ sensor like the conventional device, but can be configured extremely easily as an open loop system, and is capable of purifying exhaust gas. can. In addition, there is no system time delay unlike in conventional systems, the fluctuation period and amplitude of the air-fuel ratio are predetermined, there is no instability such as engine hunting, and there is no inconvenience such as deterioration of the catalyst. Furthermore, if the average air-fuel ratio A is set on the lean side, fuel efficiency can also be improved. In addition, since the air-fuel ratio fluctuation period, amplitude, and bias thereof can be freely set, it is possible to take measures in consideration of various performances of the nine engines, and the durability of the engine and the catalyst device can be improved. 4. Brief explanation of the drawings Figure 1 is a graph showing the characteristics of the three components of air-fuel ratio and purification rate under steady-state operation, and Figure 2 shows the purification rate when the air-fuel ratio is varied around the stoichiometric air-fuel ratio. Figure 3 is a system diagram showing the principle of this invention, Figure 4 is the first diagram of this invention.
It is a schematic diagram showing ~3 Examples. In the figure, 2 is an air cleaner and 4 is a carburetor. 6 is an intake passage, 8 is an internal combustion engine, and 10 is an exhaust passage. 12 is a three-way catalyst device, 14m, 14. 1 is a secondary intake air passage, and 16 is an air-fuel ratio control means. Agent Patent Attorney Yoshimi Saigo

Claims (1)

[Claims] In an internal combustion engine that performs exhaust gas purification using a catalyst device, an air-fuel ratio control means is provided for forcibly changing the air-fuel ratio around the stoichiometric air-fuel ratio by changing the amount of secondary air introduced into the intake system in front of the combustion chamber. An intake system air-fuel ratio control device for a catalyst device, characterized in that: