JPH033059B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a twin-barrel carburetor for an internal combustion engine (hereinafter also referred to as an engine) that performs feedback control of an air-fuel ratio.

(Prior Art) Conventionally, various methods have been proposed for controlling the air-fuel ratio of a carburetor by feeding back the air-fuel ratio of engine exhaust gas, but the following two are representative.

(1) A method that controls the fuel flow rate of the carburetor using an air bleed passage.

For example, Tokuko Sho 53-16853, Jitsugoku Sho 54-41232
There are publications etc.

(2) A method that allows secondary air to flow into the downstream side of the carburetor and controls the flow rate of this bypass air.

For example, Tokuko Sho 52-13257, Tokuko Sho 52-13586
There are publications etc.

In the above feedback control, when the air-fuel ratio of the engine exhaust gas changes to the lean side or rich side from the set air-fuel ratio, the feedback control is activated, but the time for the air-fuel ratio of the mixture to be corrected through the air-fuel ratio control means is The method of directly controlling the air flow rate is shorter than the method of controlling the fuel flow rate by changing the air flow rate of the air bleed. In other words, the bypass air control method in (2) above is better than the above.
Compared to the fuel control method (1), the air-fuel ratio control characteristics are much better.

(Problem to be solved by the invention) However, in a twin-barrel carburetor, the phases of the air flows in the main and sub air passages are different, so when using the bypass air control method, a bypass air controller is installed in each air passage. However, there was a problem in that the structure of the carburetor was complicated.

SUMMARY OF THE INVENTION An object of the present invention is to provide a feedback control carburetor with good responsiveness, which employs a bypass air control system in the main air passage and a fuel control system in the auxiliary air passage.

(Means for Solving the Problems) In order to achieve the above object, the feedback control carburetor of the present invention has a main air passage provided with a main throttle valve and a sub air passage provided with a sub throttle valve. A carburetor for an internal combustion engine, wherein an air bleed passage having a variable throttle actuator is connected to an auxiliary fuel passage leading to a vent lily portion of the auxiliary air passage, and a bypass air passage having a bypass air controller is connected to an intake manifold. The main throttle valve and the bypass throttle valve provided in the bypass air passage are connected to each other so that the main throttle valve is connected to the bypass throttle valve provided in the bypass air passage, and the main throttle valve is connected to the bypass throttle valve provided in the bypass air passage. An electronic controller is provided which sends a control signal to control opening and closing of the bypass air controller, and sends a control signal to the bypass air controller as well as a control signal to control the flow rate of the variable throttle actuator at high speeds. shall be.

(Function) When the air-fuel ratio of engine exhaust gas deviates from the set air-fuel ratio, at low speeds when the intake air flow rate is low, the bypass air controller operates in response to a control signal from the electronic controller, and a certain amount of air is bypassed. introduced into the air passage. At this time, the bypass throttle valve is opened in conjunction with the main throttle valve, and an appropriate amount of bypass air is supplied to the intake manifold from the opening of the bypass air passage, which is proportional to the change in the opening area of the main air passage. , controls the air-fuel ratio in the main air passage.

The intake air flow rate is large and the throttle of the auxiliary air passage
When the valve is open at high speed, the bypass air controller operates and the variable throttle actuator also operates in response to a control signal from the electronic controller to control the air-fuel ratio in the auxiliary air passage.

(Example) The present invention will be described below based on drawings showing examples. FIG. 1 is a partially cutaway front view of the carburetor of the first embodiment. The carburetor 1 has a main air passage 2, a main throttle valve 3, and an auxiliary air passage 4 and an auxiliary throttle valve 5. An air bleed passage 8 is coupled to an auxiliary fuel passage 7 that communicates with the bench lily portion 6 of the auxiliary air passage 4 . The flow rate in the air bleed passage 8 is controlled by a variable throttle actuator 9, which may include a step motor or a solenoid valve.

On the other hand, a bypass air passage 12 is coupled to the intake manifold 11 . A bypass throttle valve 13 is attached to the bypass air passage 12 and is operatively connected to the main throttle valve 3 by a link 14. 1
A bypass air controller 5 controls the flow rate of bypass air supplied to the intake manifold 11 through the bypass air passage 12, and is composed of a regulator body 16 and a three-way solenoid valve 17. The regulator body 16 includes a bypass air introduction passage 18, a regulator chamber 19 having a bypass air inlet and an outlet, and a regulator chamber 19.
an atmospheric pressure chamber 21 adjacent to and communicating with through a small hole, a control pressure chamber 23 provided via a diaphragm 22 adjacent to the atmospheric pressure chamber 21, and one end connected to the diaphragm 2.
2 and a regulator valve 25 having a valve 24 at the other end for opening and closing the bypass air inlet of the regulator chamber 19. Three-way solenoid valve 17
is an air vent 17a opened to the atmosphere and an intake air port 17a.
It has a negative pressure port 17b communicating with the manifold 11, the opening degree of each of which is controlled by a solenoid valve 17v operated by a control signal from the electronic controller 15, and a control pressure chamber of the regulator body 16 through the control pressure port 17c. The diaphragm 22 is operated by controlling the air pressure of the diaphragm 23.

26 is an exhaust pipe of the engine (not shown), and an exhaust gas concentration sensor 2 such as a zirconia sensor is installed.
7 is installed. 28 is an electronic controller,
The solenoid valves of the variable throttle actuator 9 and the bypass air controller 15 are controlled in response to a signal from the sensor 27.

The operation of the feedback control carburetor constructed as above will be explained. When the exhaust gas deviates from the set air-fuel ratio during engine operation, a Hi or Lo signal is sent from the exhaust gas concentration sensor 27 in the exhaust pipe 26 to the electronic controller 28. At low speeds when the intake air flow rate is low, the bypass air controller 15 operates in response to a control signal issued from the electronic controller 28, and the regulator valve 25 opens, allowing a constant amount of air to flow due to the constant negative pressure in the engine intake pipe. is introduced into the bypass air passage 12. At this time, bypass throttle valve 13 is connected to main throttle valve 3.
An appropriate amount of bypass air is supplied to the intake manifold 11 from the opening of the bypass air passage 12 which is proportional to the change in the opening area of the main air passage 2, and the air-fuel mixture in the main air passage 2 is Correct the air/fuel ratio.

At high speeds when the intake air flow rate is large and the auxiliary throttle valve 5 of the auxiliary air passage 4 is open, the variable throttle actuator 9 is activated as well as the bypass air controller 15 in response to a control signal from the electronic controller 28. do. This allows air bleed passage 8
The fuel flow rate in the auxiliary fuel passage 7 is controlled by changing the air flow rate in the auxiliary air passage 4, thereby controlling the air-fuel ratio of the mixture in the auxiliary air passage 4. In this case, since the amount of intake air is large, the response time of the fuel flow rate control by air bleed of the auxiliary air passage 4 becomes appropriately fast, and sufficient responsiveness can be obtained.

In this way, the air-fuel ratio of the exhaust gas is constantly fed back to the electronic controller 28, and the air-fuel mixture is controlled to maintain the optimum air-fuel ratio.

In the above feedback control, the air-fuel ratio controlled by the bypass air controller 15 is controlled by the variable throttle actuator 9, which has better responsiveness than indirect fuel control by air bleed because the air flow rate is directly controlled. When combined with the air-fuel ratio by fuel control, the air-fuel ratio control width becomes smaller than in the case of the air-fuel ratio control alone, and the control characteristics of the feedback control carburetor of the present invention are further improved.

FIG. 2 shows a second embodiment, in which the bypass air controller 35 includes a three-way joint 37 instead of the three-way solenoid valve 17 in the first embodiment. The three-way joint 37 receives and mixes the atmospheric air from the variable throttle actuator 39 and the negative pressure air from the intake manifold 11, and mixes it into the control pressure chamber 2 of the regulator body 16.
Send it to 3. The variable aperture actuator 39 is
It has two needle valves 39a, 39b,
39a communicates with air bleed passage 8; 39b
communicates with the three-way joint 37. The second example is
The configuration other than the above is the same as that of the first embodiment, but since a three-way joint 37 is used in place of the three-way solenoid valve 17, the system can be simplified and the cost, reliability, and mountability can be improved.

(Effects of the Invention) As explained above, this invention is a feedback control twin-barrel carburetor that employs a bypass air control method in the main air passage and a fuel flow rate control method in the auxiliary air passage. Feedback control with good responsiveness is possible at both low and high speeds, and the combination of bypass air control and fuel control reduces the control width and improves air-fuel ratio control characteristics.

[Brief explanation of the drawing]

The figures show embodiments of the invention, with FIG. 1 being a partially cutaway front view of the first embodiment, and FIG. 2 being a partially cutaway front view of the second embodiment. 2... Main air passage, 3... Main throttle valve, 4... Sub-air passage, 5... Sub-throttle valve, 6... Bench lily portion, 7... Sub-fuel passage,
8... Air bleed passage, 9, 39... Variable throttle actuator, 11... Intake manifold, 12... Bypass air passage, 13... Bypass throttle valve, 15, 35... Bypass air controller, 26...Exhaust pipe, 27...Exhaust gas concentration sensor, 28...Electronic controller.

Claims (1)

[Claims] 1. A carburetor for an internal combustion engine having a main air passage with a main throttle valve and an auxiliary air passage with an auxiliary throttle valve, wherein the air bleed passage with a variable throttle actuator is connected to a bench lily of the auxiliary air passage. connected to the auxiliary fuel passage leading to the
A bypass air passage having a bypass air controller is connected to the intake manifold, the main throttle valve and a bypass throttle valve provided in the bypass air passage are operatively connected, and the bypass air passage is attached to an exhaust pipe. In response to a signal from the exhaust gas concentration sensor, a control signal is sent to control the opening and closing of the bypass air controller when the speed is low, and a control signal to the bypass air controller and the flow rate of the variable throttle actuator is sent when the speed is high. 1. A feedback control vaporizer, characterized in that it is provided with an electronic controller that sends control signals for control.