JPS60190654A - Air-fuel ratio control device for engine - Google Patents

Abstract

PURPOSE:To supply an optimum mixture in every engine operating condition, by controlling the air-fuel ratio and amount of the mixture of an engine with the use of a step motor for controlling the amount of air bypassing a throttle valve in a carburetor and a plurality of solenoid valves arranged in parallel with each other for controlling fuel fed to a bypass passage. CONSTITUTION:Fuel is fed through a passage 11 opened to an auxiliary passage bypassing throttle valve 3 in a carburetor 1, downstream of a valve 8 which is operated by a pulse motor 10 driven by a signal from a control device 6 and which is disposed in the auxiliary passage 5. This fuel is controlled by two solenoid valves 9a, 9b which are arrange in parallel with each other and which open and close two fuel inlet ports 12a, 12b arranged in parallel with each other, in accordance with the output of the control device 26. Accordingly, the control device 26 controls the feed amounts of auxiliary air and fuel in accordance with the operating condition of the engine so that the amount and air-fuel ratio of the mixture which is fed into the engine may be arbitrarily controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air-fuel ratio control device that can precisely control the air-fuel mixture required by an engine with a simple configuration to ensure stable operation.

Single or multiple carburetors are the most common device for supplying air-fuel mixture to engines.

As is well known, a choke device is used to smoothly start and warm up the engine, and an idle rotation correction device is used to respond to load fluctuations during idling.

Control mechanisms that respond to various engine conditions, such as a deceleration countermeasure device for reducing exhaust gas during deceleration, are required to operate automatically and with high precision.

However, in a choke device, for example, the choke valve has a large influence on the accuracy of air-fuel ratio control, but the current state of the art has reached its limit and no further improvement in accuracy can be expected. Furthermore, since the control mechanism has a single function, it is necessary to provide a large number of control mechanisms, making the entire carburetor extremely complex and large. Subject to design constraints. In addition, from the point of view of fuel economy and emission control, the engine status is detected and an electronic control unit issues a control signal to control the fuel.

Feedback carburetors that control either or both of the air sources to obtain an optimum air-fuel ratio are also widely used. Therefore, if the above-mentioned control mechanism and electronic air-fuel ratio control method are used together, it becomes even more complicated and the manufacturing cost inevitably increases.

The present invention was invented for the purpose of solving these problems and providing an air-fuel ratio control device that can supply an air-fuel mixture with an optimum air-fuel ratio required by an engine with a simple configuration that integrates two functions. be.

In order to achieve this object, the engine air-fuel ratio control device according to the present invention includes an auxiliary passage that bypasses the upstream and downstream sides of the throttle valve provided in the intake passage, and a step provided in the auxiliary passage. an air control valve driven by a motor to control air flow; a fuel passage connected downstream of the control valve of the auxiliary passage and having a plurality of parallel fuel inlets; and a solenoid provided at each of the fuel inlets. A plurality of fuel control valves are individually driven to control the fuel flow rate, and an electronic control unit receives the engine operating status as an electrical signal and outputs a control signal to the step motor and solenoid. It is characterized by the following:

Next, specific examples of the present invention will be explained based on the drawings.

An intake passage 4 formed vertically in the main body 1 of the carburetor and having a bench area 2 and a throttle valve 3 and an auxiliary passage 5 are provided in parallel, and the upstream end of the auxiliary passage 5 opens toward an air horn 6. The downstream end opens toward the intake path 4 on the downstream side of the throttle valve 3 . A valve seat 7 is formed in the middle of this auxiliary passage 5, and cooperates with a conical valve body 8.
The valve seat 7 and the valve element 8 constitute an air control valve 9, and the valve element 8 is driven by a step motor IO.

A fuel passage 1 is located downstream of the control valve 9 in the auxiliary passage 5.
1 is connected, and this fuel passage 11 is connected at its upstream end to a constant oil level chamber 13 with two parallel fuel pumps α, 12J, and has a fuel jet 14 and an air bleed jet 15 in the middle, The fuel in the constant oil level chamber 13 is the fuel jet 14
The air is mixed with air taken in from the air bleed jet and enters the auxiliary passage 5, mixed with air metered by the air control valve 9, and sent to the intake passage 4.

Valve seats 16α and 16 are provided at the fuel inlets 12α and 124, respectively.
4 is provided and cooperates with the valve bodies 17α and 174 to reduce the fuel population 1.
This valve seat 16α opens and closes 2cL and 124.

16J and valve bodies 17α, 174 are fuel control valves 18α, 1
The valve bodies 17a and 174 constitute the solenoid 19α,
Each of them is driven separately by 19 factors.

The step motor 10 includes a casing, a stator 21 consisting of a plurality of electromagnets housed at equal intervals in the circumferential direction, and a rotor n consisting of a cylindrical permanent magnet placed at the center of the stator 21. The rotor n is a casing. In addition, it is fixed to a freely rotatably supported core material B, and an output pongee-like threaded portion 5 which is connected to the casing with a key is screwed into the center screw hole of this core material 3, and the output shaft Fuel shaft control valve 9 at the tip of 24
A valve body 8 is provided.

Control signals consisting of pulses are sequentially supplied to the coils of the electromagnets constituting the stator 21 to move the point where magnetic flux is generated in the circumferential direction and generate a repulsive force between the rotor 22 and the core. When pulses (7) and waves are sent to one coil, the rotor n rotates by an angle corresponding to the distance between adjacent electromagnets, and therefore the output The axis U moves linearly in the axial direction by a distance determined by the rotation angle of the rotor η determined by the wave number of the pulse and the screw pinch of the threaded part,
Since the direction of movement is determined by the order in which the coils are energized, the air control valve 9 changes the effective area of the auxiliary passage 5 almost steplessly.

A control signal consisting of pulses is also supplied to the electromagnetic coils of the solenoids 19α and 19, but this control signal causes the solenoids 19α and 19k to be repeatedly energized and demagnetized in a short constant cycle, and the electromagnetic force of the iron core and the spring are combined. The valve bodies 17α, 174 connected to the iron core are driven to open and close by reciprocating with force, and the fuel flow rate is changed by changing the ratio between the valve opening time and the valve closing time at each fixed cycle.

The two control signals are issued by the electronic control unit and are related to the engine rotational speed.

Engine coolant temperature 1. 9 valve opening of throttle, negative pressure of suction pipe.

Intake air temperature, oxygen concentration in engine exhaust gas.

The operation of equipment that generates electrical loads and the operation of exhaust gas recirculation systems 1 Appropriate sensors for detecting ignition timing are connected to the control unit +-z, and these sensors send electrical signals according to engine operating conditions. Control unit) 26 to attack. data processing the electrical signal in the control unit 26;
It determines the amount of air/fuel mixture to be replenished into the intake passage 4 and its mixture ratio, and outputs a control signal.

When starting the engine, the air control valve 9 greatly reduces the effective area of the auxiliary passage 5. Here, when starting the engine at a low temperature, give an air-fuel ratio of 1 or less during cracking, an air-fuel ratio of about 8 during complete combustion and warm-up, and an air-fuel ratio of 14 to 15 during idling after warming up. is preferable.

Two fuel control valves 18α during slave cranking.

Both the valve opening time ratios of 18α are increased, and after complete explosion, the valve opening time ratios are gradually decreased, or only one fuel control valve is opened and closed to gradually reduce the air-fuel ratio. During this time, the air control valve 9 changes its opening degree so as to supply the appropriate amount of mixture required by the engine. Three control valves 9°18α and 18
6 is driven to increase the amount of the mixture, and when the idle link ends and the opening degree of the throttle valve 3 increases and the main fuel is supplied from the main nozzle opened to the venturi 2, the air control valve 9 closes the auxiliary passage 5. Fully close the fuel control valves 18α, 184.
Both valves remain open.

Three control valves 9#18α are provided so that when the engine is decelerated, a mixture equivalent to a conventional negative pressure control reduction gear or coasting enricher that directly sends the air-fuel mixture or fuel to the downstream side of the throttle valve 3 is sent.

is, g is driven.

Furthermore, the device of the present invention can be used to replenish fuel during acceleration and high power.

In addition, during starting, warming up, and idling, low-speed fuel is supplied from the low-speed system of the carburetor in the same manner as before, and the total amount of fuel with the device of the present invention is the required amount of the engine. The low-speed system may be eliminated and the fuel required by the engine may be supplied only by the device of the present invention.

Furthermore, it goes without saying that the present invention can also be applied to a system in which three or more fuel populations 12α, 124 are provided in parallel, and to a system in which fuel is injected into the intake passage 4.

As described above, according to the present invention, an auxiliary passage is provided in the intake passage by bypassing the upstream and downstream sides of the throttle valve, and the air flow rate passing through the auxiliary passage is controlled by an air control valve driven by a step motor. In addition to stepless control, the fuel flow rate is controlled by multiple fuel control valves that are individually driven by solenoids, so the fuel flow rate is controlled in accordance with various engine operating conditions such as starting, warming up, idling, and deceleration. The electronic control unit outputs control signals separately to the step motor and solenoid, finely controlling the mixture ratio of the air/fuel mixture and the amount of air to supply the optimum mixture to the engine. In particular, since the fuel was controlled by multiple fuel control valves,
By distributing the control range to each, highly accurate control can be performed over a wide air-fuel ratio control width. As a result, starting at low temperatures can be performed reliably, and warm-up, idling, and deceleration operations can be performed stably.Furthermore, the choke action and air-fuel ratio control using the feedback method are performed by the same mechanism, making it possible to perform operations such as warm-up, idling, and deceleration in a stable manner. , idle rotation correction device, deceleration countermeasure device.

The air-fuel ratio control device is integrated, and the configuration is simplified and downsized.

[Brief explanation of drawings]

The drawing is a longitudinal sectional view of an embodiment of the invention. 3... Throttle valve, 4... Intake passage, 5... Auxiliary passage. 9... Air control valve, 10... Step motor, 11
...Fuel passage, 12a, 124...Fuel inlet, 1
8α. 184...Fuel control valve, 19α, 19k...Solenoid. But...the control unit. □ □ □ □ □ ■ ■ 書

Claims (1)

[Scope of Claims] An auxiliary passage that bypasses the upstream and downstream sides of a throttle valve provided in the intake passage, and an air stream provided in the auxiliary passage and driven by a step motor to control the air flow rate. a control valve, a fuel passage connected to the downstream side of the control valve in the auxiliary passage and having a plurality of fuel inlets in parallel, and a solenoid provided in each of the fuel ports and individually driven by each solenoid to control the fuel flow rate. 1. An air-fuel ratio control device for an engine, comprising: a plurality of fuel control valves that control the engine; and an electronic control unit that receives engine operating conditions as electrical signals and outputs control signals to the step motor and the solenoid. .