JPH01130048A - Air bleed controller for carburetor - Google Patents

Abstract

PURPOSE:To prevent an air-fuel mixture from going to over-leanness even in the case where an air bleed control valve gets out of order by installing an on-off valve which closes a bypass air bleed passage when a throttle valve of a carburetor is more than the specified opening. CONSTITUTION:In an air bleed passage 7, there is provided with an air bleed control valve 1 consisting of a needle valve 10 being controlled for its opening or closing by an electric actuator 9 and a valve seat 11. The air bleed passage 7 is branched off to a first passage 22 fitted with an air bleed throttle valve 21 and a second passage 24 provided with a piston valve 30 with a piston 25 interlocking with a throttle valve 23, in the midway. When the throttle valve 23 is more than the specified opening, the piston 25 closes the second passage 24, so that in this case even if the electric actuator 9 gets out of order and thereby an air bleed control valve 12 comes into a state of being fully opened, limited bleed air is fed out of the first passage 22.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to air bleed control when the air bleed control valve of a carburetor is left fully open and becomes uncontrollable.

(Prior art) Conventionally, air-fuel mixture A/F electronically controls detection signals from various sensors that detect engine cooling water temperature, engine rotation speed and load factor, oxygen concentration of υ1 gas, etc. input to the unit, perform program calculation processing,
The amount of air bleed necessary to match the A/F of the air-fuel mixture at that time to the operating state of the engine is calculated, and the opening degree of the air bleed control valve driven by the electric actuator is controlled.

(Problem to be Solved by the Invention) However, in this air bleed control state, if the air bleed control valve driven by the electric actuator remains fully open and becomes uncontrollable due to a short circuit in the lead wire or failure of a sensor, etc., the A/ F is overloaded, especially when it comes to acceleration, etc. ! 1if
Not only was it not possible to operate with one load, but in the worst case scenario, the engine would stop.

(Means for Solving the Problems) The present invention provides an air bleed control valve driven by an electric actuator in the air bleed passage of the carburetor to control the bleed air suspension, thereby providing engine operating characteristics corresponding to normal running of a tonnage. In a carburetor that supplies an A/F mixture compatible with
An air bleed throttle valve is provided in parallel with the air bleed passage except for the air bleed control valve in the air bleed passage, and the air bleed throttle valve has a passage cross-sectional area that corresponds to securing bleed air suspension according to preset engine characteristics, and the air bleed throttle valve is bypassed. The carburetor is provided with an on-off valve that closes the bypass air bleed passage by means of a link mechanism when the throttle valve of the carburetor reaches a predetermined opening degree close to that point or more on a part of the bypass air bleed passage. Located in the bleed air control device.

(Function) In the carburetor air bleed control device configured as described above, when the throttle valve is in a high-load operating state such as acceleration when the throttle valve is almost fully opened, the link mechanism connected to the throttle valve drive mechanism The bypass passage opening/closing valve is closed, and even if the electric actuator-driven air bleed control valve fails and remains fully open, the air-fuel mixture will be limited to the predetermined bleed air level set by the air bleed throttle valve. The air-fuel mixture is maintained at a predetermined A/F, and engine troubles due to excessive leanness are prevented. Further, when the air bleed control valve driven by the electric actuator is in a normal operating state, the electronic control unit controls the A/F to match the operating characteristics of the engine from an idle state through normal running to a high-speed operating state.

(Example) Hereinafter, the configuration of an embodiment of the present invention will be explained with reference to the drawings.

FIG. 1 shows a variable venturi type carburetor 2 that supplies air-fuel mixture to an engine 1.The upstream side of the intake pipe 3 of the carburetor'a2 is opened through an air filter 4, and the downstream side is connected to an intake manifold 6. An air bleed passage 7 opens in the boat 8 at the upstream part of the intake pipe 3, and an air bleed passage 7 consisting of a needle valve 10 and a corresponding valve seat 11, which are opened and closed by an electric actuator 9, is connected to the engine 1 through Main metering jet 13 via bleed control valve 12
It is connected to.

As shown in FIG. 2, the electric actuator 9 is a stepping motor 17 composed of a stator, a stator coil 14, a rotor 15, and a ball bearing 16 that rotatably supports the rotor 15. The core has a needle valve 1 whose movement in the circumferential direction is restricted.
Needle valve 10 that advances or retreats 0 in the axial direction
A female screw 1 that is screwed into a male feed screw 18 formed at the base of the
9 is integrally formed, and the needle valve 10 can be displaced in the axial direction as the rotor 15 rotates forward or backward.

The coil spring 20 biases the needle valve 10 in the direction of the valve seat 11, and the valve seat 11 is concentric with the needle valve 10, and the needle valve 10 is inserted into the valve seat 11 and displaced in the axial direction on the center line. The gap formed between the valve seat 10 and the valve seat 11, that is, the concentric annular area, can be increased or decreased in accordance with the bleed air suspension.

The air bleed passage 7 has an air bleed throttle valve 21 in the middle.
A piston 25, a cylinder 26, and a boat keep the bypass air bleed passage 24, which bypasses the throttle valve 21 for air bleed, in an open state except when the first passage 22 provided with a 27, a spring 28, and a crosshead 29 and a second passage 24 equipped with a piston valve 30, and then merge again to form the air bleed passage 7.

The piston valve 30 is connected to the end of a lever 32 attached to the driving rotation shaft 31 of the throttle valve 23 by a link 1 [35] consisting of a connecting rod 34 rotatably connected at a fulcrum 33 and two crossheads. At the downstream side of the intake pipe 3, there is a throttle valve 23 (not shown) whose opening degree increases or decreases in proportion to the amount of depression of the accelerator pedal, and which controls the engine 1 by supplying a corresponding air-fuel mixture to the engine 1. is provided, and is connected to an idle sensor 37 by a link mechanism 36 that is different from the link mechanism 35 that opens and closes the piston valve 30.

The intake manifold 6 of the engine 1 is provided with a pressure sensor 38 that detects the load condition of the engine 1, and the exhaust manifold 39 is provided with an oxygen concentration sensor 4o that detects the oxygen degree of exhaust gas.
The main body includes a water temperature sensor 44 that detects the temperature of cooling water in the cylinder jacket 42 in relation to the piston 41, the cylinder jacket 42, the spark plug 43, etc., and the spark plug 4.
An engine rotation sensor 45 is attached to detect the engine rotation speed from the electrical system No. 3.

Each scale sensor, etc., namely, the water temperature sensor 44 that detects whether the engine 1 is warmed up, the idle sensor 37 that detects that the throttle valve 23 is in the idle position, and whether the engine 1 is high load, medium load, or a pressure sensor 38 that detects whether the engine is in the correct condition, a rotation sensor 45 that detects the rotation speed of the engine 1, an oxygen concentration sensor 40 that detects the amount of oxygen contained in the exhaust gas of the engine 1, and a speed sensor that detects the speed of the vehicle. A vehicle speed sensor 46 and an ignition signal generator 47 that detects whether the vehicle is in a starting state.
Each piece of information is input to the electronic control unit 48 of the computer via a Δ-D converter, a waveform shaper, a converter, etc. (not shown), and after calculation processing, is sent to each controller, for example, the electric actuator 9 to control ff1D. Output.

Next, the operation of this embodiment will be explained with reference to flowchart 1 in FIG.

In the engine control air bleed control system configured as described above, when the ignition key of the vehicle is closed and the engine 1 is started, a start signal from the ignition key signal generator 47 is read in step 101, and then In step 102, the water temperature sensor 44 detects whether or not the engine 1 has been warmed up based on the temperature of the cooling water.
In step 08, the effective cross-sectional area of the air bleed passage is increased or decreased to change the air bleed strength, and the A of the air-fuel mixture supplied to the engine 1 is changed.
The control ff1D of the electric actuator 9 that controls the A/F is set to a small value that provides a rich A/F suitable for operation in low humidity conditions.

This control ff1D drives the stepping motor 17 of the electric actuator 9 to adjust the A/F so that the area of the annular gap formed by the needle valve 10 and the corresponding valve seat 11 is suitable for the state of the engine 1 at the time. As a result, a rich A/F mixture is supplied to the engine 1 to obtain stable output.

If it is determined in step 102 that No. 1, that is, the temperature of the cooling water with which the engine is warmed up, is determined to be 80° C. or higher based on the information from the water temperature sensor 44, the process proceeds to step 103, where it is determined whether or not the throttle valve 23 is in the idle position. It is determined based on the information from the idle sensor 37 articulated by the mechanism 36, and if YES, in step 109, the A/F suitable for idling operation is set in the electric 7 actuator control ff1D, and the electric actuator 9 is control 1
An opening degree corresponding to 'dl is given to the air bleed control valve 12 consisting of a needle valve 10 and a valve seat 11 to control the bleed air and obtain an appropriate Δ/F.

If the result in step 103 is No, that is, the throttle valve 23 is not in the idle position, the process proceeds to step 104, where it is determined based on the information from the pressure sensor 38 whether or not the engine 1 is in a high load state. If YES, the process proceeds to step 104. Proceeding to step 110, the electric actuator control is set to W to obtain a Δ/F suitable for high-load operation, and the bleed air barrier is controlled to supply a rich A/F mixture to the engine 1.

If it is determined in step 104 that the load is not No. 1, that is, the load is not high, based on the information from the pressure sensor 38, the process proceeds to step 105;
Same (it is determined whether the load condition of the engine 1 is cautionary based on the information from the pressure sensor 38, and if YES, the process proceeds to step 112 and the Δ/F feedback control system is applied.

In step 112, the air bleed control valve 1 is driven by the electric actuator 9 based on the information from the MLhm temperature sensor 40.
2, and performs feedback control to bring the A/F closer to, for example, the theoretical air-fuel ratio.

In other words, when the oxygen concentration sensor 40 is rich beyond the stoichiometric air-fuel ratio, the output voltage suddenly rises.
And oxygen 11! Using the relationship between the output of the oxygen concentration sensor 40 and the feedback correction coefficient α, when Δ/F shifts to the rich side, the output of the oxygen concentration sensor 40 increases rapidly almost in a step-like manner.

The electronic control unit 48 inputting this information uses a correction coefficient α
, the correction coefficient synergistic with F to be set in the control MD for the upper air actuator 9 is rapidly decreased by fPRc, and is gradually decreased as shown in 41IR.

That is, the air bleed control valve 12 consisting of the needle valve 10 and the valve seat 11 is suddenly opened by an amount corresponding to PR to increase the amount of bleed air and control the A/F to be lean, so that +AA/F is When the air-fuel ratio eventually becomes leaner than the stoichiometric air-fuel ratio and the oxygen temperature sensor output rapidly decreases, the intermediate value of the oxygen concentration sensor output is called a slice level, and the oxygen concentration sensor 40 output becomes negative with respect to the slice level.

Based on this negative information, the electronic control unit uses a correction coefficient α
First, RL is suddenly raised, and then IL is gradually raised, that is, bleed air ω is decreased, and A/F
As a result, when △/F becomes rich, the output of the oxygen concentration sensor 40 rises rapidly, and when it becomes positive with respect to the slice level, the electronic control unit 48 receives this information and controls α again. Decrease rapidly.

By repeating the above, negative feedback control is constantly applied to △/F, and if △/F is rich overall,
Since the time for the A/F to be rich is longer than the time for it to be lean, the output of the yarn resistance density sensor 40 becomes greater than the slice level, that is, the time for it to be positive increases, and α gradually shifts to become smaller. In this way, A
/F is balanced around the stoichiometric air-fuel ratio.

If it is determined in step 105 that the engine load is not medium, the process proceeds to step 106, where it is determined whether the speed of the vehicle is low based on the information from the vehicle speed sensor 46. If YES, the process proceeds to step 105. The process advances to step 112 and applies the A/F feedback control system in the same way as when the engine 1 was in the medium load state.

If it is determined in step 106 that the vehicle speed is high, the process proceeds to step 107, and the rotation sensor 45 determines whether or not the same rotational speed of the engine 1 is low.
If S, the process proceeds to step 112)) Apply the micro A/F feedback control system.

To summarize the above, A/F feedback control is applied when the engine has a medium load, the rotation speed layer is small, and the vehicle speed is low.

If NO in step 107, that is, it is determined that the 1g1 rotation speed of the engine 1 is large, the process proceeds to step 111, and the electronic control unit 48 controls the electric actuator 1 to ff1.
Issue a command to set D to L.

That is, when the load on the engine 1 is small, the vehicle is running at high speed, and the engine speed is high, the amount of bleed air is the largest and the lean A/F is used to supply the mixture to the engine 1.
Control to drive economically.

The relationship between the magnitude of the electric actuator control taω in each step is that l- is the most popular, that is, the air bleed control valve 12 controlled by the electric actuator 9 operates from the fully open state to the fully open state, and the most amount of bleed air is generated. engine 1 with the leanest A/F mixture.
supply to That is, the amount of bleed air is set in the order of L>αF≧I>W>T, and this relationship is shown in FIG.

In this way, the various states of the engine 1 and the heavy vehicle are detected by the corresponding sensors, etc., and the electronic control unit 48
The air bleed control valve 12 installed in the air bleed passage 7 should be Controlled by actuator 9.

Another air bleed control system added to the air bleed control system by the above-mentioned electronic control unit 48, namely the mechanical bleed throttle valve 21 provided in the first passage 22.
The operation of the control system based on the opening/closing mechanism of the second passage using the piston valve 30 provided in the second passage 24 will now be described.

The piston valve 30 provided in the second passage 24 is connected to the link 1
The piston 25 is linked to the throttle valve 23 by the lf1335, and when the throttle valve 23 opens beyond a predetermined opening close to fully open, the piston 25 moves toward the boat 2 as shown in FIG.
7 is closed to prevent bleed air from passing through the second passage 24.

Therefore, the bleed air can only pass through the first passage 22, and the air bleed throttle valve 21 provided in the first passage 22 restricts the bleed air to a predetermined amount. When the accelerator pedal is pressed to request high-load operation of the engine 1, such as when accelerating, and the throttle valve 23 is fully open or close to 1771 degrees, even if the electric actuator 1 fails and the air bleed control valve opens fully. Even under these conditions, the amount of bleed air is limited to the amount that can accommodate the rich A/F mixture required by engine 1's high-load operation, so the d1 heavy alloy at the specified A/F is supplied to the engine. .

(Effects of the Invention) The present invention relates to a system for controlling the A/F of the air-fuel mixture supplied to an engine, in which an electronic control unit controls the opening degree of an air bleed control valve driven by an electric actuator, and a single item of bleed air is controlled. By adding a separate control device to the control device that increases or decreases the A/F mixture that is suitable for the engine load condition, it is possible to increase or decrease the engine speed, especially when suddenly accelerating the vehicle. 17 of the electric actuator drive when a high load is required.
This prevents the bleed control valve from failing and becoming fully open, resulting in the mixture being too lean and the engine not being able to accelerate, or in the worst case scenario, stopping.

That is, an air bleed throttle valve is provided in the air bleed passage of the carburetor to limit the bleed air when the first ab bleed control valve is in the fully open state due to failure, while the opening of the throttle valve is set to an opening close to that of the rumor. In the range from idling to normal driving, the air bleed throttle valve is bypassed to allow bleed air to pass through to ensure bleed air and prevent the mixture from becoming unnecessarily rich, while also under normal operating conditions. Operation can be continued at an economical air-fuel ratio without interfering with the A/F control by the multiplex control unit.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an engine control system including an air bleed control system according to an embodiment of the present invention, FIG. 2 is a sectional view of a road body driven by an electric actuator, FIG. 3 is a flowchart of the control system, and FIG. The figure is an operational characteristic diagram explaining the feedback control system, and FIG. 5 is the air bleed control valve 12 driven by the electric actuator 9.
FIG. 6 is a detailed diagram of the main part of FIG. 1. 1... Engine 2... Carburetor 7.
...Air bleed passage 9...Electric actuator 12...Air bleed control valve 21...Air bleed throttle valve 22...First air bleed passage 23...Slot valve

Claims (2)

[Claims] (1) In a carburetor that provides an air bleed control valve driven by an electric actuator in the air bleed passage of the carburetor to control the amount of bleed air and supply the engine with an A/F mixture corresponding to arbitrary operating characteristics, An air bleed throttle valve having a passage cross-sectional area corresponding to securing a bleed air amount according to preset engine characteristics is provided in parallel with the air bleed passage excluding the air bleed control valve in the air bleed passage, and the air bleed throttle valve is bypassed. An air bleed control device for a carburetor, characterized in that a bypass passage opening/closing valve for opening and closing a part of the bypass air bleed passage is provided so as to be interlocked with a throttle valve. (2) The air bleed control device according to claim 1, wherein the arbitrary driving characteristics are driving characteristics corresponding to normal driving of the vehicle.