JPH033956A - Air-fuel ratio control device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of the hunting phenomenon and improve the operation performance and exhaust purification performance by providing a bypass air quantity correcting means correcting the bypass air quantity operated according to a load so as to keep the control width of the air-fuel ration constant. CONSTITUTION:When the intake air quantity is small and the negative pressure of the venturi section 12 of a carburetor 14 is weak, the correcting valve body 50 of a bypass air quantity correcting valve 36 is pushed by the displacement of a diaphragm 40, and a correcting valve hole 52 is closed to decrease the bypass air quantity for correction. The bypass air quantity is decreased at the low-load side of an internal combustion engine 4 for correction. When the intake air quantity is large and the negative pressure of the venturi section 12 of the carburetor 14 is strong, it is retreated by the displacement of the diaphragm 40, and the correcting valve hole 52 is opened to increase the bypass air quantity for correction. The bypass air quantity is increased at the high-load side of the internal combustion engine 4 for correction.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an air-fuel ratio control device, and particularly to an air-fuel ratio control device that controls the control width of the air-fuel ratio controlled by the operation of a bypass air amount adjusting means, regardless of load fluctuations of an internal combustion engine. By keeping it constant, the amount of bypass air introduced by the bypass air passage can be made proportional to the amount of intake air introduced by the intake passage,
The present invention relates to an air-fuel ratio control device that can improve driving performance and exhaust purification performance.

[Conventional technology]

2. Description of the Related Art Some internal combustion engines are equipped with an air-fuel ratio control device in order to improve combustion conditions and reduce fuel consumption and harmful exhaust gas components. As shown in FIG.
The air cleaner 11 is sequentially installed in the intake passage 108 from the upstream side.
0, a carburetor 112, and an intake throttle valve 114, and a bypass air passage 116 is provided that communicates the upstream intake passage 108A and the downstream intake passage 108B of the carburetor 112, which are provided in the middle of the intake passage 108. Bypass air passage 1
A bypass air amount adjusting valve 118, which is a bypass air amount adjusting means, is provided in the middle of the air pump 16, and connected to a control section 120, which is a control means. Further, an Ot sensor 126 is provided in the exhaust passage 124 of the exhaust pipe 122 communicating with the internal combustion engine 104 as an exhaust sensor for detecting exhaust component values.
, a sensor 126 is connected to the control section 120.

As a result, the air-fuel ratio control device 102 controls the o2 sensor 12.
The output signal of 6 is manually inputted to the control unit 120, and this control unit 1
20 operates the bypass air amount adjusting valve 118 to adjust the bypass air introduced through the bypass air passage 116 and control the air-fuel ratio to converge to the target value.

In addition, as a device for controlling an internal combustion engine,
There is one disclosed in Japanese Patent No. 192846.

The technology disclosed in this publication corrects the engine speed control speed according to the intake pipe pressure when the internal combustion engine is idling, thereby quickly and stably converging the actual engine speed to the target engine speed, and improving control response. It has improved characteristics.

[Problems to be Solved by the Invention] By the way, in the air-fuel ratio control device, a proportional solenoid valve or the like is used as a bypass air amount adjusting means for adjusting the amount of bypass air, and this proportional solenoid valve is not fixed. When the air-fuel ratio is controlled so as to converge to the target value by operating at a drive period of a certain value, as shown in FIG. 5, the control range of the air-fuel ratio becomes large on the low load side, while it becomes small on the high load side. Since the opening area of this proportional solenoid valve is determined by the control width on the high load side, the amount of bypass air is not proportional to the load, as shown in Figure 6. In other words, the amount of intake air introduced by the intake passage The amount of bypass air introduced by the bypass air passage is not proportional to the amount of intake air, and on the low load side where the amount of intake air is small, the amount of bypass air becomes excessive relative to the amount of intake air, which tends to cause a hunting phenomenon, which impairs operational performance and exhaust gas. This has the disadvantage of reducing cleaning performance.

In this case, by providing an intake air amount sensor and an intake air pressure sensor and controlling the air-fuel ratio control width using a control means so as to be able to maintain it constant regardless of load fluctuations,
Although it is possible to solve the problem of the amount of bypass air being too large relative to the amount of intake air on the low load side, this increases the cost by increasing the number of parts and changing the control program. .

Therefore, by maintaining the air-fuel ratio control width constant regardless of load fluctuations so that the air-fuel ratio control width does not change from the low load side to the high load side, the bypass air amount can be made proportional to the intake air amount. Therefore, it is desired to realize an air-fuel ratio control device that can eliminate the above-mentioned disadvantages.

[Purpose of the invention]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to maintain the control range of the air-fuel ratio, which is controlled by the operation of the bypass air amount adjusting means, constant regardless of load fluctuations of the internal combustion engine, so that the amount of intake air introduced through the intake passage can be bypassed. The object of the present invention is to realize an air-fuel ratio control device that can proportionate the amount of bypass air introduced by an air passage and improve driving performance and exhaust purification performance.

[Means for solving problems]

To achieve this object, the present invention provides a bypass air passageway for introducing bypass air into an intake passageway downstream of a carburetor of an internal combustion engine by means of a control means that inputs a detection signal from an exhaust sensor provided in an exhaust passageway of the internal combustion engine. In an air-fuel ratio control device that controls the air-fuel ratio to converge to a target value by operating a bypass air amount adjusting means provided in the internal combustion engine, the control range of the air-fuel ratio controlled by the operation of the bypass air amount adjusting means is The present invention is characterized in that a bypass air amount correcting means is provided which is operated according to the load of the internal combustion engine and corrects the amount of bypass air in the bypass air passage so as to maintain the amount constant regardless of load fluctuations.

[Effect]

According to the configuration of the present invention, the bypass air passage is operated according to the load of the internal combustion engine in order to maintain the control width of the air-fuel ratio controlled by the operation of the bypass air amount adjusting means constant regardless of load fluctuations of the internal combustion engine. By providing a bypass air amount correction means for correcting the bypass air amount of
To maintain the control width of an air-fuel ratio constant regardless of load fluctuations of an internal combustion engine without increasing the control width of the air-fuel ratio on the low-load side of an internal combustion engine and without decreasing it on the high-load side. I can do it.

〔Example〕

Next, embodiments of the present invention will be described in detail based on the drawings.

1 to 3 show embodiments of this invention. In the figure, 2 is an air-fuel ratio control device.

The air-fuel ratio control device 2 includes an air cleaner 10, a carburetor 14 equipped with a fixed venturi portion 12, and an intake throttle valve 16, which are sequentially provided from the upstream side in an intake passage 8 of an intake pipe 6 that communicates with the internal combustion engine 4. A carburetor 1 provided in the middle of the intake passage 8
A bypass air passage 18 is provided which communicates the upstream intake passage 8A and the downstream intake passage 8B of No. 4. This bypass air passage 18 is connected to the air cleaner 1 in this embodiment.
The starting end is opened at 0, and the terminal end is opened at the intake passage 8B on the downstream side of the intake throttle valve 16.

A bypass air amount adjusting valve 20 serving as bypass air amount adjusting means is provided in the middle of the bypass air passage 18, and connected to a control section 22 serving as a control means. The bypass air amount adjustment valve 20 may include, for example, a coil 24 that is excited by electricity and a conical adjustment valve body that is operated by the coil 24 to open and close an adjustment valve hole 26 provided in the bypass air passage 18. 28, and uses a proportional type operated at a fixed drive cycle using a magnetic valve or the like.

Further, the exhaust passage 32 of the exhaust pipe 30 communicating with the internal combustion engine 4 is provided with an Ox sensor 34 which is an exhaust sensor for detecting exhaust component values.
It is connected to and installed.

Thereby, the air-fuel ratio control device 2 inputs the detection signal of the O2 sensor 34 to the control unit 22, and the control unit 22 operates the bypass air amount adjustment valve 20 to control the bypass air introduced by the bypass air passage 18. and control the air-fuel ratio to converge to the target value.

In such an air-fuel ratio control device 2, in order to maintain the control width of the air-fuel ratio controlled by the operation of the bypass air amount adjustment valve 20 constant regardless of load fluctuations of the internal combustion engine 4, the air-fuel ratio is adjusted according to the load of the internal combustion engine 4. A bypass air amount correction valve 36 is provided as a bypass air amount correction means that is operated to correct the amount of bypass air in the bypass air passage 18.

In this embodiment, the bypass air amount correction valve 36 is provided in the middle of the upstream side bypass air passage 18A on the upstream side of the bypass air amount adjustment valve 20. The venturi section 1 of
It is operated by a negative pressure of 2 and corrects the amount of bypass air in one day in the bypass air passage.

That is, the bypass air amount correction valve 36 is provided with a diaphragm 40 inside the main body 38, and a negative pressure chamber 42 is partitioned by the diaphragm 40 on one side of the diaphragm 40 inside the main body 38, and this negative pressure chamber 42 is guided. A pressure passage 44 communicates with a negative pressure boat 46 provided in the bench area 12 of the carburetor 14 . On one side of the diaphragm 40,
A pressing spring 48 is elastically installed in a direction to expand the negative pressure chamber 42.

Further, on the other side of the diaphragm 40, the bottom side of a correction valve body 50 formed in a conical shape is fixedly provided. This correction valve body 50 has its tip end connected to the upstream side bypass air passage 1.
The bypass air amount is corrected by opening and closing the correction valve hole 52, which is provided in the middle of the valve 8A. In addition, the code|symbol 18B is bypass air amount adjustment valve 2
This is a downstream side bypass air passage downstream of 0.

Next, the effect will be explained.

When the internal combustion engine 4 is driven, the air-fuel ratio control device 2 inputs the detection signal of the Ox sensor 34 to the control unit 22, and the control unit 22 operates the bypass air amount adjustment valve 20 to introduce air into the bypass air passage 18. The bypass air is adjusted to control the air-fuel ratio to converge to the target value.

At this time, negative pressure is generated in the venturi section 12 of the carburetor 14 due to the drive of the internal combustion engine 4, and this negative pressure is applied to the negative pressure boat 4.
6 is introduced into the negative pressure chamber 42 of the bypass air amount correction valve 36 through the pressure guiding passage 44 .

This negative pressure is proportional to the amount of intake air introduced through the intake passage 8.

As a result, the bypass air amount correction valve 36
The diaphragm 40 is displaced by the negative pressure introduced into the diaphragm 40 and the pressing force of the pressing spring 48, and the correction valve body 50 is moved forward and backward by the displacement of the diaphragm 40 to open the correction valve hole provided in the upstream bypass air passage 18A. By opening and closing 52, the amount of bypass air in the bypass air passage 18 is corrected in proportion to the amount of intake air introduced by the intake passage 8, and therefore in accordance with the load of the internal combustion engine 4.

That is, the correction valve body 50 of the bypass air amount correction valve 36 is
When the amount of intake air is small and the negative pressure in the venturi section 12 of the carburetor 14 is weak, the displacement of the diaphragm 40 causes the diaphragm 40 to be pushed forward, and the correction valve hole 52 is closed, thereby reducing the amount of bypass air. to correct. Thereby, the bypass air amount correction valve 36 corrects the amount of bypass air to decrease on the low load side of the internal combustion engine 4.

On the other hand, the correction valve body 50 of the bypass air amount correction valve 36 is
When the amount of intake air is large and the negative pressure in the venturi section 12 of the carburetor 14 is strong, the diaphragm 40 is displaced to perform a retiring operation, and the correction valve hole 52 is opened, thereby making corrections to increase the amount of bypass air. do. Thereby, the bypass air amount correction valve 36 corrects the bypass air amount to increase on the high load side of the internal combustion engine 4.

In this way, on the low load side of the internal combustion engine 4, the bypass air amount correction valve 36 corrects the bypass air amount to decrease, so that the control width of the air-fuel ratio by the bypass air amount adjustment valve 20 is reduced on the low load side. It never gets bigger. Also, on the high load side of the internal combustion engine 4, the bypass air amount correction valve 3
Since the bypass air amount is corrected by 6 to increase the bypass air amount, the control width of the air-fuel ratio by the bypass air amount adjustment valve 20 does not become small on the high load side. Therefore, the control width of the air-fuel ratio by the bypass air amount adjustment valve 20 is
As shown in the figure, the load can be maintained constant regardless of load fluctuations of the internal combustion engine 4.

Therefore, as shown in FIG. 3, the amount of bypass air can be made proportional to the load, that is, the amount of bypass air introduced by the bypass air passage 18 can be made proportional to the amount of intake air introduced by the intake passage 8. Therefore, the amount of bypass air does not become excessive with respect to the amount of intake air on the low load side where the amount of intake air is small. As a result, the hunting phenomenon can be prevented from occurring, and the driving performance and exhaust purification performance can be improved.

In addition, in this embodiment, the fixed venturi part 1
Although the bypass air amount correction valve 36 was operated by the negative pressure of the venturi section 12 of the carburetor 14 equipped with the carburetor 14, the present invention is not limited to this.

For example, FIG. 4 shows another embodiment of the present invention. In FIG. 0, 54 is a variable venturi section;
is a vaporizer. The carburetor 56 equipped with the variable venturi section 54 is configured to move the piston 60 of the variable venturi section 54 into and out of the intake passage 8 using the intake pipe negative pressure and the pushing force of the pushing spring 58. It is a formula.

A carburetor 5 equipped with such a variable venturi section 54
6, a bypass air amount correction valve 62 is provided as a bypass air amount correction means that is operated by utilizing the movement of the piston 60 into and out of the intake passage 8 and corrects the amount of bypass air.

That is, the bypass air amount correction valve 62 is connected to the upstream side bypass air passage 18A on the upstream side of the bypass air amount adjustment valve 20.
It is located in the middle of the. This bypass air amount correction valve 6
2, the main body 66 is fixed to the container body 64 of the vaporizer 56;
A valve chamber 68 through which the upstream bypass air passage 18A flows is provided within the main body 66. Further, one end side of a loft 72 is fixed to a base end portion 70 of the piston 60 that constitutes the venturi portion 54 of the carburetor 56 on the side opposite to the intake passage 8. The rod 72 extends in the direction in which the piston 60 moves in and out, and has its other end located within the valve chamber 68 . A correction valve body 74 formed in a conical shape is fixed to the other end of the rod 72 inside the valve chamber 68 .

The correction valve body 74 has its pointed end fixed to the tip of the other end of the loft 72 . This correction valve body 74 has its bottom side oriented in the direction of protrusion and retraction movement of the piston 60, and the valve chamber 6 through which the upstream bypass air passage 18A flows.
It is inserted into a correction valve hole 76 provided in 8.

According to this other embodiment, the bypass air amount correction valve 62 has the piston 60 of the variable venturi portion 54 moved in and out of the intake passage 8 by the intake pipe negative pressure and the pushing force of the pushing spring 58. Due to this movement of the piston 60, the correction valve body 7
4 is moved forward and backward to open and close the correction valve hole 76, the amount of bypass air in the bypass air passage 18 is adjusted in proportion to the amount of intake air introduced by the intake passage 8, and therefore in accordance with the load of the internal combustion engine 4. will be corrected.

That is, the correction valve body 74 of the bypass air amount correction valve 62 is
When the amount of intake air is small and the negative pressure of the venturi portion 54 of the carburetor 56 is weak, the piston 60 is retracted by the protruding operation and the correction valve hole 76 is closed, thereby reducing the amount of bypass air. to correct. As a result, the bypass air amount correction valve 62 corrects the amount of bypass air to decrease on the low load side of the internal combustion engine 4.

On the other hand, the correction valve body 74 of the bypass air amount correction valve 62 is
When the amount of intake air is large and the negative pressure in the venturi section 12 of the carburetor 14 is strong, the piston 60 is pushed forward by the retracting operation, and the correction valve hole 76 is opened, thereby increasing the amount of bypass air. Correct to. Thereby, the bypass air amount correction valve 62 corrects the bypass air amount to increase on the high load side of the internal combustion engine 4.

In this way, on the low load side of the internal combustion engine 4, the bypass air amount correction valve 62 corrects the bypass air amount to decrease, so that the air-fuel ratio control range by the bypass air amount adjustment valve 20 is adjusted to the low load side. It never gets bigger. Also, on the high load side of the internal combustion engine 4, the bypass air amount correction valve 6
2, the bypass air amount is corrected to increase, so the control width of the air-fuel ratio by the bypass air amount adjusting valve 20 does not become small on the high load side. Therefore, the control width of the air-fuel ratio by the bypass air amount adjustment valve 20 is
As shown in the figure, the load can be maintained constant regardless of load fluctuations of the internal combustion engine 4.

Therefore, as shown in FIG. 3, the amount of bypass air can be made proportional to the load, that is, the amount of bypass air introduced by the bypass air passage 18 can be made proportional to the amount of intake air introduced by the intake passage 8. Therefore, the amount of bypass air does not become excessive with respect to the amount of intake air on the low load side where the amount of intake air is small. As a result, the hunting phenomenon can be prevented from occurring, and the driving performance and exhaust purification performance can be improved.

In addition, in this other embodiment, in the carburetor 56 equipped with the variable venturi portion 54, a bypass is operated using the movement of the piston 60 into and out of the intake passage 8 to correct the amount of bypass air. Although a bypass air amount correction valve 62 as an air amount correction means is provided, a variable venturi portion 54 is provided.
A bypass air amount correction valve may be provided as a bypass air amount correction means that directly introduces the negative pressure of the variable venturi portion 54 of the carburetor 56 to correct the bypass air amount.

〔Effect of the invention〕

As described above, according to the present invention, the bypass is operated according to the load of the internal combustion engine in order to maintain the control width of the air-fuel ratio controlled by the operation of the bypass air amount adjusting means constant regardless of the load fluctuation of the internal combustion engine. By providing the bypass air amount correction means for correcting the amount of bypass air in the air passage, the control width of the air-fuel ratio does not become large on the low load side of the internal combustion engine, and does not become small on the high load side of the internal combustion engine. , the control width of the air-fuel ratio can be maintained constant regardless of load fluctuations of the internal combustion engine.

Therefore, the amount of bypass air can be made proportional to the load, that is, the amount of intake air introduced by the intake passage can be made proportional to the amount of bypass air introduced by the bypass air passage, so the amount of intake air can be reduced. On the low load side, the amount of bypass air does not become excessive with respect to the amount of intake air, and the hunting phenomenon can be prevented from occurring, and the driving performance and exhaust gas purification performance can be improved.

[Brief explanation of drawings]

Figures 1 to 3 show examples of the present invention, Figure 5 is a diagram showing the relationship between load and control width, Figure 6 is a diagram showing the relationship between load and bypass air amount, and Figure 7 is a diagram showing the relationship between load and control width. FIG. 2 is a schematic explanatory diagram of a fuel ratio control device. FIG. 4 is a schematic explanatory diagram of an air-fuel ratio control device showing another embodiment of the present invention. 5 to 7 show conventional examples, FIG. 5 is a diagram showing the relationship between load and control width, FIG. 6 is a diagram showing the relationship between load and bypass air amount, and FIG. 7 is air-fuel ratio control? FIG. 1 is a schematic explanatory diagram of an Ill device. In the figure, 2 is an air-fuel ratio control device, 4 is an internal combustion engine, 8 is an intake passage, 10 is a fixed venturi part, 14 is a carburetor, 18 is a bypass air passage, 20 is a bypass air amount adjustment valve, and 22 is a control 32 is an exhaust passage, 34 is a 0□ sensor, and 36 and 62 are bypass air amount correction valves.

Claims (1)

[Claims] 1. Bypass air amount adjusting means provided in the bypass air passage for introducing bypass air into the intake passage downstream of the carburetor of the internal combustion engine by means of a control means inputting a detection signal of an exhaust sensor provided in the exhaust passage of the internal combustion engine. In the air-fuel ratio control device that operates to control the air-fuel ratio to converge to a target value, the control width of the air-fuel ratio controlled by the operation of the bypass air amount adjusting means is maintained constant regardless of load fluctuations of the internal combustion engine. An air-fuel ratio control device comprising a bypass air amount correction means that is operated according to the load of the internal combustion engine and corrects the amount of bypass air in the bypass air passage.